The Character of Joe Gargery in Great Expectations Essay

The Character of Joe Gargery in Great Expectationsnbsp;nbsp; nbsp; The protagonists brother-in-law, Joe Gargery, in the novel Great Expectations, written by Charles Dickens, is prominently humane, especially compared to the other characters. Although Pip is the psychological center of the book, Joe is the moral center. Pip struggles to be good; Joe merely is obedient by nature without apprehending it. Although Joe is not prosperous or knowledgeable, he still offers what he does know and have, to Pip. Joe provides a perfect example of however one conducts oneself in life; ones good nature always asserts itself at the end. With Joes humane intellect, he is like a father to Pip- giving him guidance, informing him what†¦show more content†¦Prosperous or impoverish, given Joes humane mind and good nature, he is willing- under any circumstances- to help those in need.nbsp; Another example of a humane deed committed by Joe is as follows on page 74, chapter 9 when Joe lectures Pip about deceit after he confides in Joe about the lies he told to his family about Miss Havishams: `Theres one thing you may be sure of, Pip, said Joe, after some rumination, `namely, that lies is lies. Howsever they come, they didnt ought to come, and they come from the father of lies, and work round to the same. Dont you tell no more of em, Pip. That aint the way to get out of being common, old chap. This illustrates that Joe is not only Pips friend, but more like a father figure in Pips life; Pip feels comfortable confiding in him, and is open to listen to Joe about what is right and what is wrong. Without Joe, Pip would be lost; he would not have anyone to guide him, tell him what is right and wrong, constantly remind him what is important in life, or to occasionally knock some sense into him. He stands out as a loving figure in Pips life. Joe and Pip share a relationship based on love and trust, easily likened to the relationship between father and son, or brothers. Without Joe, Pip would not be the same character or share any of the characteristics that he does now; he would be a despondent, ignorant, perplexed orphan.Show MoreRelatedFemales Influences on Pip in Great Expectations Essay856 Words   |  4 PagesFemales Influences on Pip in Great Expectations By Charles Dickens There are many influences on Pip’s life regarding his thoughts on women. This would therefore mean that Pip would take his views on women from those that were a played a major role in his life, for example: * Mrs Joe Gargery is Pip’s sister and has raised Pip because their parents have died. Mrs Joe Gargery has raised both Joe Gargery and Pip by hand as she is not happy with the wayRead MoreJoe Gargery Character Analysis716 Words   |  3 Pagesto care, love, and listen to him, and Joe Gargery was that person for Pip. In the novel, The Great Expectation, Joe Gargery, Pip’s brother-in-law who whole heartedly takes Pip in and raised him as his own, became a father to Pip. As the novel progresses, Joe eventually became more than a father; he was Pip’s confidant, his conscience, and Dickens uses Joe to bring a moral side to the novel. In The Great Expectations, Charles Dickens characterizes Joe Gargery as a commendable guy, who does thingsRead MoreThe Elements of Fortune and Contentment Dissected in Great Expectations by Charles Dickens688 Words   |  3 Pagesand jovial with your life? Joe Gargery showed that wealth doesn’t define one’s personality but personality defines ones wealth, Miss Havisham shows that wealth is everything but that emotions don’t matter, and Jaggers shows that some gentlemen have dispirited lives despite all of their riches. Characters in the novel such as Joe Gargery, Miss Havisham, and Jaggers represent that life is not always perfect whether someone is rich or poor. In the novel, Great Expectations, Charles Dickens uses theRead MoreDickens Techniques of Characterisation in Great Expectations1117 Words   |  5 Pagesof Characterisation in Great Expectations Many characters in Great Expectations are a rich and varied mix of personalities, in particular Pip, Joe Gargery and Mrs. Joe. The physical description of the characters is an example of the techniques used by Charles Dickens. Other techniques include the speech and habits of the characters, the characters interaction with others, the choice of the characters name and their surroundingsRead MoreCharles Dickens Great Expectations1335 Words   |  6 Pagesin the family was to help provide the money .Since the men were more superior than the women, they received more rights like the right to vote. In the novel Great Expectations, Charles Dickens uses the characters in the book to portray the gender roles, social classes and the changing of classes in the Victorian era. In Great Expectations, Charles Dickens shows the gender roles of men as living within different social spaces. Unlike most women, the men had the social existence that was free toRead MoreGreat Expectations Character Names Essay869 Words   |  4 PagesHello, 7H! The book that I’ve chosen for the Challenging Read Project is Great Expectations by Charles Dickens. Great Expectations is the thirteenth novel written by him; a few of Dickens other books are, A Christmas Carol, David Copperfield and Oliver Twist. Dickens is even viewed by many people as the ‘greatest novelist of the Victorian era’, an exceptionally prestigious title. How does Charles Dickens uses character names? Here are some examples: Abel Magwitch, the convict - The name MagwitchRead MoreAnalysis Of Miss Havisham s House 958 Words   |  4 Pagesthe middle of nowhere near a cemetery. His house is also the blacksmith shop. He lives with his mean sister and her nice husband, Mr. and Mrs. Joe Gargery. After his sister dies he leaves his house to go to London. Character: The Main Character of the book is Pip Pirrip. In the beginning of the book he is very young and lives with Mr. and Mrs. Joe Gargery his adopted family. In the beginning of the book he gets in trouble with a homeless man asking for food. When he turned a certain age, he wouldRead MoreGreat Expectations By Charles Dickens943 Words   |  4 PagesGreat Expectations written by Charles Dickens consist of many dynamic characters and literary elements that help develop the novel. Dickens introduces the life of the main character, Phillip Pirrip better known as Pip, as he works his way up in society. Along the way, Pip encounters many minor characters such as Biddy to help realize his full potential. Through the use of several literary devices, for example, characterization, conflict, and imagery, we take a young naà ¯ve boy and develop him intoRead MoreSymbolism Of Charles Dickens Great Expectations1017 Words   |  5 PagesCharles Dickens’ Great Expectations Great Expectations by Charles Dickens follows the life of the orphan, Pip. We first meet him as a tiny, terrified child in a village churchyard. Years later, through the help of an anonymous benefactor, Pip will travel to London, full of expectations to become a gentleman. But his life is already inextricably tangled in a mystery that surrounds a beautiful woman, an embittered recluse, and an ambitious lawyer. (barnesandnoble.com, Great Expectations) SymbolismRead MorePersonal Ambiguity In Great Expectations1397 Words   |  6 Pagesone seeks to analyze it. The search for self, as well as knowing and trusting one’s self is echoed through out literature humanity; it could be haunting and cause great trepidation, to hold on to a vision that could alter their judgement; as well can cause a fierce storm in the supreme realm that is objective truth. Great Expectations, by Charles Dickens, is a coming of age story of a young man named Pip, seeking to establish stability, as we ll as find meaning in his life through love and self identification

Essay Strategy To Combat The Climate Crisis - 1824 Words

Strategy to Combat the Climate Crisis Introduction Human activities are contributing to global warming by adding large amounts of heat-trapping gases to the atmosphere. Our fossil fuel use is the main source of these gases. Every time we drive a car, use electricity from coal-fired power plants, or heat our homes with oil or natural gas, we release carbon dioxide and other heat-trapping gases into the air. The second most important addition of greenhouse gases to the atmosphere is related to deforestation, mainly in the tropics, as well as other land-use changes. Global warming and its effects The science behind global warming is often portrayed as enormously complex, but some of it is quite simple. It begins with a ray of†¦show more content†¦Wonders such as the Great Barrier Reef and the Amazon could collapse under the weight of just a few more degrees. And hundreds of millions of people may be forced from their homelands as the climate shifts, creating increased political and economic instability. Stopping global warming is urgent. We have just a few years to turn around the growth of greenhouse gas emissions in order to avoid the worst effects. The greater the magnitude and rate of warming, the greater the chances are for truly devastating - and potentially irreversible - changes in the Earths climate system. Even by acting today to reduce our emissions from cars, power plants, land use, and other sources, we will see some degree of continued warming for a period of time because past emissions will stay in the atmosphere for decades or more. But, the window for effective action is closing fast and responding to theShow MoreRelatedThe Climate Change Of California1285 Words   |  6 Pagesend of the century1. With the rise of temperature, the climate of California would also be changed. 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Even if one city chooses not to carry out such a program, it doesRead MoreEnvironmental Issues Of Human Rights Violations947 Words   |  4 Pagesdefining the environmental issues as human rights violations in legal terms is a complex task. However, in the last decade, petitions and suit cases against climate change issue were gradually filed. In 2006, the first suit case against the Environment al Protection Agency was reached to the U.S Supreme Court (Aminzade, 2006). A petition claimed that climate change through emissions and air pollutants caused harm to public health and welfare. This case grabbed the attention of multiple environmental agencies;Read MoreEconomic And Social Development : Thailand Still Faces Critical Health Issues859 Words   |  4 Pagestotal deaths are a result of NCDs2. However, combatting NCDs proves difficult as development largely reflects individual behavior. Careful surveillance is needed3, without it tracking implications of behaviors is unreliable and developing prevention strategies is difficult with lacking data on epidemiological trends. Though preventable, they are often detected when advanced. Long term cases need proper management. But with a shortage of rehabilitative personnel tertiary care is threatened, this must beRead MoreAssignment 2: Global Warming: Cause and Mitigation1137 Words   |  5 Pagesglobal warming. Over the last f ew decades climate change have lead scientist to develop a theories that human beings are the major contributors to the global warming crisis. Many theories suggest that different types of issues contribute to the warming of the planet but the mitigation strategies to slow this process down vary as well. When speaking of this topic there are two basic types of climate change, natural and anthropogenic. 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It had bec ome evident that American foreign policy needed to be reengineered, particularly as a result of important political tensions, including the Cuban missile crisis. Foreign Policy under Eisenhower The â€Å"New Look,† the brainchild of Eisenhower and his cabinet, would be characterized by a greater reliance on nuclear weapons and force as a means to combat theRead MoreWhat Type Of Unique It Solutions Would Help Local And / Or State Governments? Why?1127 Words   |  5 Pagespackage Desire to help combat climate change hindered by economic crisis Major Issues (1) The most serious infrastructure challenge facing cities; (2) How infrastructure budgets are being affected by the global economic crisis; (3) Stimulus infrastructure priorities (4) Obstacles to implementing climate change mitigation measures; (5) Promising technologies for reducing the impact of infrastructure on climate change; (6) Measures to help adapt to the impacts of climate change; and (7) ImprovingRead MoreGarbage Collection And The Waste Of Garbage1659 Words   |  7 Pagescrops. This example, in its most rudimentary form, represents the current climate change crisis that faces our world today. Who is responsible for the amount of greenhouse gas emissions in our atmosphere and how do we allocate responsibility amongst the nations of this world? The complex nature of this crisis makes the question proposed difficult to answer. 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Domestic Violence against Women-Free-Samples-Myassignmenthelp.com

Question: Write an Article on Journal of Emotional Abuse. Answer: The purpose of the article is to present the miserable condition of the women in Israel in terms of the domestic violence. The article is based on ethical and legal considerations of the healthcare staffs while screening the victimized women from the domestic violence. The article is an argumentative one as this presents the ethical and moral dilemma of the healthcare staffs between the raising the voice and valuing the individual autonomy and the safety of the patient who has been subjected tub the victims of the domestic violence. Therefore, the article aims to highlight the screening of the domestic violence in regards to the ethical dilemma. The article presents several facts that are relevant to the purpose of the article. It is found at the very beginning of the article that the domestic violence is one of the most common matters in the society. Along with this, the domestic violence is one of the burning and common issues in Israel. It is found that the one in the seven women have been victimized of their intimate partners or their husbands at least once in their lifetime. It is common to be abused once in a week or once in a month. Ben Natan et al. (2014) opined that Ministry of Labour and Social Affairs published that 20,000 files were opened in 2008 that were reported for violent offenses between spouses. However, the numbers of the reports on the domestic violence has never been decreased, and rather it has been raised at 4% from 2007 (Ben-Natan, 2014, pp. 809). The article discuses the context of the battered women as they are assaulted by their intimate partner repeatedly both in the form of emotional and physical. However, the assault most of the time had taken the form of beating, slapping, nonconsensual sexual relations. The article presents the data that one woman is abused by her intimate partner every 9 seconds (Ben-Natan, 2014, pp. 809). On the other hand, the article presents the legal perspectives of the domestic violence on the women. It is found from the article that the only minimal percent of the cases are reported regarding the domestic violence, whereas every one woman is been abused once in a day. The author states that it is not true that the nation does not have proper law for protecting the women from the domestic violence, but it is the society that is projecting the matter of the domestic violence as a common matter. Therefore, the e women do not always report the abusive behavior that they have been getting from their intimate partners. The legal perspective of the nation does not definitely promote the domestic violence, but there are some laws which are pulling behind the women to report the matter of victimization. The general laws state that if the healthcare authority finds any person injured or unconscious or dead, the authority can report to the welfare officer or to the police in terms of the suspicion about the cause being the domestic violence (Ben-Natan, 2014, 810). However, this regulation is also applicable for the healthcare staffs and the doctors. Therefore, it is evident there is no obligation for anyone to report agonist his/her intimate partners if they are committing any domestic violence. However, the article presents the fact that the reporting against the intimate partners to the police can cause the women to bear more abuse. The article presents the ethical dilemma of the healthcare professionals in terms of repotting the physical abuse of the women. The healthcare professionals suffer from the dilemma between the safety of the patients and the respect the autonomy of the patients (Ben-Natan, 2014, 812). The article states that the women who are the victim of the domestic violence suffers from the curtailed autonomy and possess poor decision making ability. The research on the victimization of the women from the domestic violence refers to the fact that it is the victims who often deny reporting the abuse to the police. The victims are completely dependent on their partners and this co dependent relationship is the reason for these women to possess poor ability in decision making (Alaggia Vine, 2013). The article highlights that these women feel obliged to stay with their violent and abusive spouses as the result of their concern for their children. The women also fear that if they or the health care pr ofessionals report to the police about their spouses for being violent and abusive at them, they with their children will be left with no home and income (Ben-Natan, 2014, pp. 812). As the result of this fear, when questioned by the healthcare professionals about the injury, their self confidence is threatened. They feel that answering these questions can endanger their lives and therefore, they feel abused by the healthcare professionals. This situation leads the healthcare professionals to suffer from a ethical and moral dilemma for they fear that the abused women can deny of being abused and as the result of that the care professionals may be penalized (Alaggia Vine, 2013). It must be noted that the violence over the women of Israel was not an unusual matter and therefore the most of the women do not lodge any report against their spouses or the initiate partners. The article presents the data on the reporting of the women for being tortured, which shows that 7.3% women self support the domestic violence compared to the all women who are being victimized daily (Ben-Natan, 2014, pp. 813). At the same time, there are very low percentage of women who discuss their helpless plight and the miserable situation due to the domestic violence with the healthcare professionals or the doctors. The remaining victimized women are more in numbers and do not like to be questioned by the healthcare workers regarding the domestic violence. However, it is important to remember and understand that the identification of the abused women is important in order to provide them proper medication and mark the rate of violence in the nation. In addition, the identification is als o needed for the health assessment because there are many women who are subjected to abuse during their pregnancy. As the result of the abuse during this delicate time, these women face severe and sensitive health issues. Apart from the impact of the violence on the physical health of the women, the mental of them is also disrupted by the same. It is noteworthy that the relationship of the women with their intimate partners or the spouses is based on fear and uncertainty. The nature of the women becomes submissive. In addition, they also suffer from the mental illness. This is another reason that strengthens the need for the medical help for the women. The medical professionals are subjected to provide proper and mandatory screening to the women who are the victims of the domestic violence. However, this must be mentioned that the process of screening is only meant for the women and not for the men. This is obviously a contradictory regulation by the government of Israel which is further capable of creating the ethical dilemma within the healthcare professionals. Therefore, from the discussed discourse it is assured that the women in Israel, are the victims of the domestic violence and this issue despite of being the major importance is hidden. The initial part of the analysis of the article shows the numeric data of the violence and the report of the same to the police. On the other hand, the discourse also marks that the rate of abuse is increasing and every other women is victimized once in a day. Although, there are several laws that protect the women from being abused, but the fear of losing the identity is resulting them to not report the violence they are encountering by their intimate partners. On the other hand, driven by the fear of losing the identity and the support from the family, the behavior and the reaction of the women change when they are questioned by the healthcare professionals about the reason of their injury (Alaggia Vine, 2013). This denial of the victimized women further becomes a threat to the healthcare profession als that pulls them back from reporting to the police against the violence and abuse. This can be assumed from the above discourse that the victimization of the women in Israel is not reported due to the fear of the women for losing their identity as well as the family support. The article provides the fact that the urban areas of Israel have not yet accepted and implemented the governmental laws on the protection of the women from the domestic violence (Ben-Natan, 2014). It is found that the basic purpose of the women is to provide happiness to their spouses irrespective of their abusive nature. Along with this, these women perceive the any questions about their domestic violence as offensive and unethical, since they are afraid of their domestic secret to be out in public (Alaggia Vine, 2013). Apart from the this general reaction of the victimized women, the fact is also clear from the article that the women being driven by the fear of the abuse are obsessed with following the assaulters wishes. The victims become obsessed and accustomed with the violence that they think it is normal to bear the abusive behavior of their spouses. Therefore, they when asked about the domestic violence become aggressive towards the healthcare professionals as they fear that if the brutal secret of the violence is out they might face severe consequences from their spouse or intimate partners. Even if there is any wish or desire or the urge within the women to express the feelings and the pain that they are getting from their spouses, they suppresses it. Overall, the personality and the desire of the victimized women are suppressed due to the fear of being abused more severely and they tend to adopt the pattern of behavior that is devoted towards the happiness of their spouses (Alaggia Vine, 2013). As the result to this, the healthcare professionals are unable to report against the However, the article is basically focused on the healthcare professionals and their ethical dilemma on the matter of the domestic violence and necessity to report the same. The author throughout the article presents the legal statement of the government regarding the domestic violence and what the healthcare professionals do in a situation where the women is the victim of the domestic violence. However, the point of educating the society is completely missed out in the article. This point can be questioned by the scholars that whether it is enough to the make the healthcare professionals and the women aware of the domestic violence and the need to report the same. It has been taken for granted in the article that the domestic violence is common and natural by the intimate partners of the women. However, the article repeatedly emphasizes upon the necessity to report the violence to the police, but it has not been mentioned anywhere in the article that the society must be educated in t erms of eliminating the victimization of the women due to the domestic violence. It is not possible to screen every woman and make them report to the police against their spouses or intimate partners as they are already victimized and scared. Therefore, the need for educating the society lies there. References: Alaggia, R., Vine, C. (Eds.). (2013).Cruel but not unusual: violence in Canadian families. Wilfrid Laurier Univ. Press. Ben-Natan, M. (2014). Screening by healthcare staff for domestic violence against women in Israel-ethical and legal aspects.Journal of family violence,29(7), 809-813.

The Adventures Of Sherlock Holmes Essay Research free essay sample

The Adventures Of Sherlock Holmes Essay, Research Paper The Adventures of Sherlock Holmes The two chief characters of The Adventures of Sherlock Holmes are Dr. John Watson and Sherlock Holmes. They are both complex characters in their ain ways, though Holmes is more cryptic. This may be because Watson narrates the narratives, so we can see what he thinks and feels. About Holmes we merely see what Watson thinks of him, and what he says. It could be hard to see why two so really different people are friends, but each has his ain ground for go oning the association, based on his personality and what benefits he gets out of working with the other. Dr. Watson is a doctor in general, civil pattern. He is an old friend and helper of Holmes # 8217 ; , who shared suites with Holmes before his matrimony. Watson is non every bit smart as Holmes, but has his ain endowments, and is much more earthy. We will write a custom essay sample on The Adventures Of Sherlock Holmes Essay Research or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page He is more practical than his friend, concerned with inside informations of day-to-day life more than with theories and thoughts, though those things hold a distant involvement for him. He has his ain life, but he is loyal to Holmes because he finds Holmes # 8217 ; eccentricities and head interesting, and because they have been friends for some clip. Bing with Holmes gives him a opportunity to see the adult male # 8217 ; s encephalon, which Watson openly admires, in action, every bit good. He besides gets a opportunity to prove his ain head against the jobs they encounter. He seems to bask the play of his friend # 8217 ; s life and work, speech production of Holmes as a absorbing animal, more machine than adult male at times. Unraveling the enigma of who Holmes is seems to be one of his chief motives, every bit good as his ain desire for escapade, even if he stays much more grounded than his friend. Sherlock Holmes himself is a investigator with an unusual attack and personality. He has temper swings, is addicted to cocaine, plays the fiddle and makes speedy tax write-offs about what he observes that seem like thaumaturgies to most people. He can be hard to cover with, traveling from cranky to playful, and ever a few stairss in front of everyone else mentally. It seems that he has problem maintaining himself in cheque at times, and gets into most problem when he doesn # 8217 ; Ts have something to busy his astonishing encephalon. His yesteryear is slightly cryptic, and though he is clearly a adult male of many endowments # 8211 ; camouflage, tax write-off, music, pugilism, and observation # 8211 ; he can sometimes be nescient of really basic things. He is besides lone and unemotional, non interested in love, as Watson points out in the first narrative, A Scandal in Bohemia, stating # 8220 ; All emotions, and that one peculiarly, were detestable to his cold, precise but laudably balanced mind. # 8221 ; ( Doyle, p. 7 ) . Holmes is contemptuous of society in general, though he normally respects its regulations and understands it, if merely as an perceiver. This makes it even more interesting that he seeks to contend offense, and therefore protect the society he has small usage for. Though he does non ever demo it, he is loyal to Watson, and finds his aid as an perceiver and a individual to resile thoughts off of utile. He besides enjoys holding his ain chronicler, thinks Watson is a good hearer, and comments a few times, fancifully, that without the physician he would be lost. The Adventures of Sherlock Holmes is a aggregation of short narratives. These narratives are fictional. Each is an history of a instance that Sherlock Holmes, aboard Dr. Watson, has worked on. They are enigmas, normally get downing with a client coming to see Holmes in his Baker Street suites, though some have more unusual beginnings, as in The Man With the Twisted Lip where Watson practically stumbles on a instance in advancement in an effort to assist a patient in his attention place from an opium lair. These narratives are told by Watson, as he follows Holmes # 8217 ; tax write-offs and work piece by piece until the enigma is solved. Most of the clip, Watson knows no more about what is traveling on than the reader does, as he carefully reports what he sees and hears, but can non think what Holmes is believing or why he takes certain actions. Each narrative begins with an debut to the job, so an account of its elements, so describes how Holmes goes about work outing it. Normally they end with Holmes explicating each measure in his methods to Watson. Though they are enigmas, non all the narratives involve a offense. Many of the instances are about unusual events or people, such as the 2nd one in the book, The Red-Headed League, about a adult male who gets tricked by a secret plan to deflect him while work to interrupt into a bank is undertaken. Another, The Adventure of the Blue Carbuncle, begins with a lost chapeau and Christmas goose and becomes a hunt for a gem stealer. Holmes is most interested by such uncommon offenses. There are 12 narratives included in the book, though the order seems to be slightly random, so they are merely by and large in chronological order. I liked this book because it is interesting to read about how Sherlock Holmes solves jobs, and because Watson is at that place to do certain every measure of Holmes # 8217 ; work is explained. Even though the narratives are unusual, they are realistic and clever. The best portion of the book is the interaction between Holmes and Watson, nevertheless, non needfully the instances themselves, and the character of Holmes, who is really complex. In some narratives the secret plan seems to roll a small spot, with characters supplying more background inside informations than seems necessary, but this helps to do them more credible. I would urge this book to person who enjoys enigmas, or merely likes mystifiers, but there is a batch to bask in it besides the enigma facet. The dialouge is ever interesting because of how otherwise Holmes and Watson see the universe. I think most readers would place more with Watson but be more funny about Holmes. The author makes England in the 1800s really graphic, so those interested in historical scenes would besides wish this book. Another interesting character that appears in The Adventures of Sherlock Holmes is Helen Stoner, in The Adventure of the Speckled Band. She first appears dressed in black and veiled, in Holmes # 8217 ; sitting room. She is really hard-pressed, and when Holmes asks her what makes her tremble, presuming it is the cold, she answers, # 8220 ; It is fear, Mr. Holmes. It is terror. # 8221 ; ( Doyle, p. 120 ) She goes on to explicate the history of her stepfather, who has turned violent, angry, acquiring into bash and prosecuting in assorted unusual behaviours, and how her twin sister died one dark two old ages before, after speaking of hearing uneven whistle in the dark. Watson describes her, when she lifts her head covering, as being Haggard, merely around 30 but looking much older with emphasis and fright. She is startled by Holmes # 8217 ; ability to infer things from her visual aspect, but tells her awful narrative carefully, paying attending to inside informations. She is a small melodramatic, though what she has been through is surely serious, but it fits in with the general tone of the narratives. Though she is afraid of him, she attempts to cover up for her stepfather # 8211 ; Holmes notices contusions left by him on her carpus, which she attempts to pardon by stating # 8220 ; He is a difficult adult male, and possibly he barely knows his ain strength. # 8221 ; ( Doyle, p. 124 ) . Miss Stoner shows herself to be, even in her fright, concerned with etiquette. She is ever proper, and speaks exactly, non frequently rolling from her point. She has a good memory for inside informations, and is able to associate exact conversations she had. Watson and Holmes don # 8217 ; t discourse her much, though it is clear they feel regretful for her quandary, covering with an opprobrious and perchance homicidal stepfather and holding lost her twin sister. Even the frequently cold Holmes comments that she has been # 8220 ; cruelly used # 8221 ; when he sees the contusions, and Watson and Holmes agree that it is a baleful state of affairs. When Miss Stoner # 8217 ; s stepfather shows up after she has left, Holmes merely puts off his inquiries, disregarding them, committed to assisting the adult female. The narrative ends with the decease of the stepfather, and after that reference of Miss Stoner is left to a speedy sum-up. Watson explains that she was brought to the attention of her aunt, bespeaking that even after the decease of her tormenter she did non retrieve wholly. However, despite her panic and terror, she comes across as holding strength, so the reader might conceive of she finally picks up the pieces of her life. Helen Stoner is a good illustration of a character in Adventures, realistic and interesting in a manner that has the reader rooting for Holmes # 8217 ; triumph over her jobs. Holmes about ever succeeds in work outing his instances, leting the reader to experience that person can convey order to a helter-skelter and sometimes evil society. Good work forces and rational thought can win the twenty-four hours. Bibliography 1. Doyle, Arthur Conan. The Adventures of Sherlock Holmes. New York: Oxford Press, 1998.

The pros of mandatory service

Introduction Students appear to be overwhelmed by the myriad of activities that make up their school programs. Many would argue that this would be just another burden for them. However, choosing such a stance would obscure the long term merits of the program. Focusing on the short discomforts of mandatory voluntary service causes one to miss out on the great benefits that can emanate from the program. Not only would participants gain work-related skills like team-building and time management, they would also develop a deep community identity.Advertising We will write a custom research paper sample on The pros of mandatory service specifically for you for only $16.05 $11/page Learn More Why the bill should become law Mandatory community or military service would strengthen students’ association with their communities. As students volunteer in hospitals, fire departments, drug recovery centers and others, they will get to learn about unmet needs in their community (Worrall 15). This could compel them to become passionate about filling those gaps and thus more active in their adult life. For instance, a training psychologist could learn about the lack of adequate follow-through in drug rehabilitation centers and this could propel him or her to become a better professional in the future. Alternatively, if a person finds that things are working well in his or her community, the volunteer could develop a sense of pride. He or she will appreciate the valuable work that other people are putting into his or her area of residence. Therefore, the program will enhance community identity and ownership over initiatives. One may also argue that modern American youth are too consumer-oriented (Longo 93). Most of them tend to focus on their individual needs rather than that of their surroundings. These young men and women only care about what they can get out of their parents or the government rather than what they can give back. National vo luntary services would enable such persons to connect with forces beyond themselves and develop a moral outlook (Sauerwein 15). Mandatory volunteer work will strengthen students’ prospects for employment. Individuals who work in community services must build rapport with others. They need to know teamwork as they must consult with paid professionals, fellow volunteers, or beneficiaries of the programs (Light 81). Additionally, these persons must plan their time adequately in order to fit it into their school routine. They will thus learn time management skills. Several students are already doing volunteer work and they do not even know it. One indication of this trend is participation in internship programs. Internship often gives students an added advantage in job recruitments (Shivaun 43). Consequently, the same may be said of the proposed mandatory community program. Opportunities and skills obtained from the plan would be priceless. For instance, individuals would build n etworks in their desired career line, and this could enhance their prospects for finding employment.Advertising Looking for research paper on education? Let's see if we can help you! Get your first paper with 15% OFF Learn More Conclusion Students require opportunities to make them more marketable to employers, and voluntary service is one such avenue. The consumerist attitude that pervades western societies has caused American youth to become self-centered. This policy could foster a greater moral attitude among the country’s citizenry. In essence, such a policy would make participants better professionals because they would learn about inadequacies in current arrangements. This could cause them to foster change in their professions. Some short term sacrifices always have to be made in order to realize a greater good. Students, parents, employers and other stakeholders will appreciate the proposed law once they see the gains of the policy. Works Cited Light, Ri chard. Making the most of college: Students speak their minds. Harvard: HUP, 2001. Print. Longo, Nicholas. Why community matters: Connecting education with civic life. NY: SUNY press, 2007. Print. Sauerwein, Kristina. â€Å"A compelling case for volunteers.† The American School Board Journal 183.3 (1996): 29-31. Print. Shivaun, Perez. Assessing service learning using pragmatic principles of Education. Texas: Texas State University Press, 2000. Print. Worrall, Laurie. â€Å"Asking the community: A case study of community partner perspectives.† Michigan Journal of Community Service Learning 14.1(2007): 5-17. Print.Advertising We will write a custom research paper sample on The pros of mandatory service specifically for you for only $16.05 $11/page Learn More This research paper on The pros of mandatory service was written and submitted by user S0l0 to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

Analysis of teen magazines.

Analysis of teen magazines. The main theme the cover of the widely known magazine, Cosmopolitan, is trying to convey is sex. There are three captions that are bold and stand out with bright yellow writing. Each caption has the word sex in it and that is the main idea this magazine is getting through to these young women or teenagers. Cameron Diaz, a pretty and famous actress is on the cover of the magazine. She is in a sexy pose with a low cut spaghetti strap tank top in order to catch guys' attentions who are passing by the magazine stand and to attract the girls who would do anything to be or be like her.There are 54 different featured columns or stories. Of the 54, 48 of them have to do with beauty, sex, celebrities, and/or fashion. There are a few stories that are meaningful; however 95% of the magazine is all about superficialities.James G. Howes and Welsh actress Catherine Zeta Jo...A few examples of some titles are 101 sex tips, His sexiest time, Fall's Perfect Pants, Beauty news, Tackling touchy subject s in bed, Women who seduce teens, Bedroom blog, and so on. As one can tell by just the titles, this magazine revolves around very superficial ideas and con women into thinking that it is a necessity to be up to date with all the celebrity drama and new fashion styles. The theme that stands out to me the most is how to improve the girl's sex life. I understand now, why girls are so pressured and eager to start having sex at such a young age. It is all around them flashing at them everywhere they go and they will obviously get curious and want to experience the "big hype" for themselves.There are ads every couple of pages and 77 out of the 90 ads...

Case study Example | Topics and Well Written Essays - 500 words - 65

Case Study Example It has been very aggressive in its profit responsibility; using its programs and projects as means of communication to showcase its products and services to a larger population. This has demonstrated to be even more effective than the traditional way of holding advertising campaigns. The overall mission of Toyota is to contribute to the society and the economy by producing high-quality products and services. This is achieved through the Toyota way, which is a philosophy, built on five principles: challenging long-term visions and approaching them with creativity, Kaizen i.e. continuously improve business processes. Genchi Genbustu which, means going to the source to verify the facts in order to make accurate decisions; stimulating teamwork and performance and finally respect for the others and the environment by responsibility for it. Thus, Toyotas concept of sustainable mobility is key to achieving the Toyota way, which believes in respecting the atmosphere, and taking care of it. The Toyota National Parks project has been very successful. Parks included in this partnership are Yellowstone National Park, Great Smoky Mountains National Park, Everglades National park, the Golden Gate Bridge Foundation, Yosemite National park, the Grand Canyon and the Santa Monica National Recreational reserves. The program tries to engage with the visitors at the park personally and expose them to Toyota’s hybrid vehicles which when used in a natural setting are able to receive messages about sustainable mobility. A corporate image study which was recently conducted shows that Toyota ranked highest among its competitors namely Toyota, Honda, Ford and GM when it came to indicators such as ‘Leader in High MPG’, ‘Leader in Technology Development’, ‘Environmentally Friendly Vehicles’ and in the ‘Wins Environmental Awards’ (107). I would suggest that Toyota gets involved in even more activities that raise environmental-friendly awareness. They should be proactive

Health Promotion Package for Diabetes Essay Example | Topics and Well Written Essays - 2000 words

Health Promotion Package for Diabetes - Essay Example Health promotion can take varied forms, depending on the concerned groups or individuals. Different constructs of health and well-being exist. In the context of Edna, various constructs are applicable in enhancing her well-being and health status. The constructs are multi-perspective and addresses various health concerns highlighted in the case study. Most relevant constructs includes; Social model theory of health promotion remains addressed from different perspective. It does not focus on medical profession domain alone. The social model does not entirely rely on the medical model on addressing various health issues. A multi-perspective approach that includes all the individual experiences and defined places are taken into consideration in this approach. Principally, there is a correlation dynamic interaction between the social structures and the concerned human agency. In addressing the medical conditions of Edna, a multi-perspective social model can find use in efficiently remedying her health concerns. Psychological model differs from medical model from the test that confirms and qualify an individual as sick. While the medical model may require an independent test to determine a medical condition, psychological model relies mostly on the psychological examinations that do not involve medical tests. For the case of Edna, psychological therapy may help relieve conditions such as stress due to death of the husband. Psychological model relies more on the subjective manifestation of the condition rather than the objective determinants of a given condition. Medical model of disease management utilizes the scientific theories and doctor patient relationship in managing a disease condition. Independent objective test are carried to determine specific condition affecting an individual. The medical models rely on the use of medicine in the management of health. For the case of Edna, medical

Pamantasan ng Lungsod ng Marikina Essay Example for Free

Pamantasan ng Lungsod ng Marikina Essay There are lots of effects which DotA brings to our society, to be particular, the youth. With no doubt this game is one of the hottest game in the market. In every Cyber Cafe you can see gamers stick with their screen and mouse and  keyboard, with their face that full of concentration and excitements finding ways to defeat their opposing team or enemies. Actually Computer games or DotA serves as a platform for youth to communicate. Teenagers who initislly don’t know each other can easily become friends through Computer games or playing DotA. Chapter I Introduction DotA effects have been continue for several years since the launch of the War of War Craft and the Frozen Throne. Almost every people especially the youth has played this game at the very beginning of the years. What is the content that DotA offers to the gamers? And how’s the excitements that brings towards the gamers. And you may ask a key question, how long will DotA effects last? The lifestyle of the youth who have been playing Computer Games especially DotA is affected by the game. There are both advantage and disadvantages for them. Let’s talkl about the advantages first. As one of the most playable games online, DotA can make the players become alert in the mental, They will also turn to be strategic and cooperative through computing the magic, damages, gold, physical reduction, present and other stuff, they will get more lore in mathematics. Thus the youth can also get some benefits on playing Computer games. Statement of the problem or Thesis Statement Why is Computer games or DotA so Addicting to Students? 1. A Time killer Boredom is the most common problem of most people today. DotA can consume a lot of time without you even noticing it . you just say after the game â€Å"WTF !, Im late !† 2. Non-exhasuting game Unlike basketball or other physical sports , you can play DotA until you can still mangae to sit, look at the monitor, use mouse and keyboard and think, Yes , using your is aslo tiring but it’ll takes an average of 3 games before you’d want to take a rest 3. Fame Source Most players want to be the best in this game to gain fame which I find natural but technically nonsense. I have to admit that thirst for fame drove me to practice and improve my game. After getting the fame I wanted, I asked myself â€Å"Now what?†. For players who don’t have plan on having DotA as their profession ,Fame isn’t that important. 4. Team work game When we were kids, we already love having team battles. That’s why a lot of team sports games cames up and multi-player computer games have been invented. Playing with teammates is more addicting than playing alone. 5. Tranquilizing DotA makes you forget your problems and make you think of simpler problems (like how to win the game) 6. Non violent war We love wars. That’s why there are shows like Wrestling, UFC ,Action films , etc. DotA is a chance to engage in wars safely. We can fight all day long and just stand up from our computer without even having a scratch on our face. 7. Easy to play Surveys shows that DotA is played by more people thatn other strategy like Starcraft. One of the reason is its simplicity. You only have to control one hero (great news for people who are not into doing micros.) 8. No height or physical disadvantages In basketball you cannot have a team composed of 5 short players. In Rugby , you should be muscular. In DotA you can be as thin and as short as you want and still own everyone. 9. Losing makes you thirsty to win On the other hand, losing is still addicting because you become more urge to have that wonderful feeling of winning. 10. Winning feels Good Yup, winning in every game makes you feel good and addicting. Background of the Study Significance of the study How to overcome DotA Addiction ? 1. Accept responsibility The problem lies within the individual, not within DotA. No attempt at beating addiction can succeed until the individual accepts its existence. 2. Identify the Impact How many hours a day do you spend playing DotA? Do you normally go out on the weekend?When was the last time you read a book?Identifying the negative impacts of the addiction will help you focus on positive improvements and getting back the things that you really are missing. 3. Avoid Blame Blaming others for problems that you alone must face does not solve the problems. 4. Set limits If you decide that you have 1 hour per day to spend playing DotA. Since DotA requires many hours of gameplay to have fun, you likely should consider a different game or different genre of games. 5. Stay positive Be positive whenever possible. While negative reinforcement is sometimes necessary, positive reinforcements will always go further in the end. What is DotA ? DotA is basically game expanded from version of War of War Craft, which initially a strategic game similar to Red Alert Series. But eventually evolved into current state. Gamers can play Dota in a Wide range ; from single player, local LAN, or LAN over internet connection with various country’s gamers. There contain variety of Heroes to be chosen as your character, There are many type of gaming modes , and different type of map for the game modes. There are lots of gamers who are more expert in the world of playing DotA . Chapter V Summary and Conclusion Summary and Conclusion We know that Playing computer games especially DotA brings bad effects to the students, they influenceed by the other gamers like â€Å"trash talks† they know how to gamble because they are playing DotA for â€Å"pustahan†. DotA really affects the lifestyle of the youth who are into this game, although it has one good benefit, but it corrupts the mind and the way the youth think. It also weakened the body system, money and moral values were not given importance because of this game.

Model for Predicting Fatigue Life of Nanomaterials

Model for Predicting Fatigue Life of Nanomaterials Introduction In the past, the primary function of micro-systems packaging was to provide input/output (I/O) connections to and from integrated circuits (ICs) and to provide interconnection between the components on the system board level while physically supporting the electronic device and protecting the assembly from the environment. In order to increase the functionality and the miniaturization of the current electronic devices, these IC devices have not only incorporated more transistors but have also included more active and passive components on an individual chip. This has resulted in the emerging trend of a new convergent system[1] Currently, there are three main approaches to achieving these convergent systems, namely the system-on-chip (SOC), system-in-package (SIP) and system on package (SOP). SOC seeks to integrate numerous system functions on one silicon chip. However, this approach has numerous fundamental and economical limitations which include high fabrication costs and integration limits on wireless communications, which due to inherent losses of silicon and size restriction. SIP is a 3-D packaging approach, where vertical stacking of multi-chip modules is employed. Since all of the ICs in the stack are still limited to CMOS IC processing, the fundamental integration limitation of the SOC still remains. SOP on the other hand, seeks to achieve a highly integrated microminiaturized system on the package using silicon for transistor integration and package for RF, digital and optical integration[1] IC packaging is one of the key enabling technologies for microprocessor performance. As performance increases, technical challenges increase in the areas of power delivery, heat removal, I/O density and thermo-mechanical reliability. These are the most difficult challenges for improving performance and increasing integration, along with decreasing manufacturing cost. Chip-to-package interconnections in microsystems packages serve as electrical interconnections but often fail by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that integrated chip (IC) packages will have interconnections with I/O pitch of 90 nm by the year 2018 [2]. Lead-based solder materials have been used for interconnections in flip chip technology and the surface mount technology for many decades. The traditional lead-based and lead-free solder bumps will not satisfy the thermal mechanical requirement of these fine pitches interconnects. These electronic packages, even under normal operating conditions, can reach a temperature as high as 150C. Due to differences in the coefficient of thermal expansion of the materials in an IC package, the packages will experience significant thermal strains due to the mismatch, which in turn will cause lead and lead-free solder interconnections to fail prematurely. Aggarwal et al [3] had modeled the stress experienced by chip to package interconnect. In his work, he developed interconnects with a height of 15 to 50 micrometre on different substrate using classic beam theory. Figure 1 shows the schematic of his model and a summary of some of his results. Although compliant intrerconect could reduces the stress experienced by the interconnect, it is still in sufficient. Chng et al. [4] performed a parametric study on the fatigue life of a solder column for a pitch of 100micrometre using a macro-micro approach. In her work, she developed models of a solder column/bump with a pad size of 50micrometre and heights of 50 micrometre to 200 micrometre. Table I shows a summary of some of her results. Table 1.1: Fatigue life estimation of solder column chip thickness (micrometre) 250 640 640 640 board CTE (ppm/K) 18 18 10 5 solder column height (micrometre) Fatigue life estimation/cycle) 50 81 N.A 171 3237 100 150 27 276 3124 150 134 31 518 4405 200 74 38 273 5772 It can be seen from Table 1.1 that the fatigue lives of all solder columns are extremely short. Apart from the 5ppm/K board where there is excellent CTE matching, the largest fatigue life of the solder column is only about 518 cycles. As expected, the fatigue life increases significantly when the board CTE decreases from 18ppm/K to 10ppm/K and as the height increases from 50micrometre to 200micrometre.This is mainly due to the large strain induced by the thermal mismatch as shown in Figure 1.2. The maximum inelastic principal strain was about 0.16 which exceeds the maximum strain that the material can support. Although the fatigue life of the chip to package interconnection can be increases by increasing the interconnects height, it will not be able to meet the high frequency electrical requirements of the future IC where they need to be operating at a high frequencies of 10-20 GHz and a signal bandwidth of 20 Gbps, By definition, nanocrystalline materials are materials that have grain size less than 100nm and these materials are not new since nanocrystalline materials have been observed in several naturally-occurring specimens including seashells, bone, and tooth enamel [5, 6]. However, the nanocrystalline materials have been attracting a lot of research interest due to its superior mechanical and electrical properties as compared to the coarse-grained counterpart. For example, the nano-crystalline copper has about 6 times the strength of bulk copper [7]. Furthermore, the improvement in the mechanical properties due to the reduction in grain size has been well-documented. Increase in strength due to the reduction in grain-size is predicted by the Hall-Petch relationship which has also been confirmed numerically by Swygenhoven et al [8] and was first demonstrated experimentally by Weertman [9]. The implantation of nanocrystalline copper as interconnect materials seems to be feasible from the processing viewpoint too. Copper has been used as interconnects materials since 1989 whereas nano-copper has also been widely processed using electroplating and other severe plastic deformation techniques in the past few years. For instance, Lu et al. [10] have reported electroplating of nano-copper with grain size less than 100 nm and electrical conductivity comparable to microcrystalline copper. Furthermore, Aggarwal et al [11] have demonstrated the feasibility of using electrolytic plating processes to deposit nanocrystalline nickel as a back-end wafer compatible process. However, there are certain challenges regarding implantation of nanocrystalline copper as interconnects materials. As discussed above, nanocrystalline copper have a high potential of being used as the next generation interconnect for electronic packaging. However, it is vital to understand their material properties, deformation mechanisms and microstructures stability. Although the increase in strength due to the Hall-Petch relationship which has also been confirmed numerically and experimentally by Weertman [9], the improvement in the fatigue properties is not well documented and no model has been established to predict/characterize these nano materials in interconnection application; conflicting results regarding the fatigue properties have also been reported. Kumar et al [12] reported that for nano-crystalline and ultra-fine crystalline Ni, although there is an increase in tensile stress range and the endurance limit, the crack growth rate also increases. However, Bansal et al. [7] reported that with decreasing grain size, the tensile stress range increases but the crack growth rate decreases substantially at the same cyclic stress intensity range. Thus, nanostructured materials can potentially provide a solution for the reliability of low pitch interconnections. However, the fatigue resistance of nanostructured interconnections needs to be further investigated. Since grain boundaries in polycrystalline material increases the total energy of the system as compare to perfect single crystal, it will resulted in a driving force to reduce the overall grain boundary area by increasing the average grain size. In the case of nanocrystalline materials which have a high volume fraction of grain boundaries, there is a huge driving force for grain to growth and this presented a presents a significant obstacle to the processing and use of nanocrystalline copper for interconnect applications. Millet et al [13] have shown, though a series of systematic molecular dynamics simulations, grain growth in bulk nanocrystalline copper during annealing at constant temperature of 800K can be impeded with dopants segregated in the grain boundaries regions. However, it has been observed that stress can trigger grain growth in nanocrystalline materials [14] and there is no literature available on impeding stress assisted grain growth. There is an impending need to investigate the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth Dissertation Objectives The goal of present project is to develop a model for the fatigue resistance of nano-materials that have been shown to have superior fatigue resistance. Accordingly, the following research objectives are proposed. Develops a model for predicting fatigue life of nanostructured chip-to-package copper interconnections Develops a fundamental understanding on the fatigue behavior of nanocrystalline copper for interconnect application Addresses the issue on the stability of nanocrystalline materials undergoing cyclic loading Overview of the Thesis The thesis is organized so that past research on nanocrystalline materials forms the basis of the understanding and new knowledge discovered in this research. Chapter 2 reviews much of the pertinent literature regarding nanocrystalline materials, including synthesis, deformation mechanisms, and grain growth. Chapter 3 describes a detailed overview of the technical aspects of the molecular dynamics simulation method including inter-atomic potentials, time integration algorithms, the NVT NPT, and NEPT ensembles, as well as periodic boundary conditions and neighbor lists. Include in this chapter is the algorithms for creating nanocrystalline materials used in this dissertations.. Chapter 4 describes the simulation procedure designed to investigate and develop the long crack growth analysis. The results of the long crack growth analysis will be presented at the end of Chapter 4. Chapter 5 presents the result and discussion on mechanical behavior of single and nanocrystalline copper subjected to monotonic and cyclic loading whereas Chapter 6 presents the result and discussion on the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth. Finally, conclusions and recommendations for future work are presented in Chapter 5. Chapter 2 This chapter offers an expanded summary of the literature published with regards to the fabrication methods, characterization, and properties of nanocrystalline materials in addition to a description of existing interconnect technology. 2.1 Off-Chip Interconnect Technologies Chip-to-package interconnections in microsystems packages serve as electrical interconnections but they will often failed by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that interconnections of integrated chip (IC) packages will have a I/O pitch of 90 nm by the year 2018 [2]. The International Technology Roadmap for Semiconductors (ITRS) roadmap is a roadmap that semiconductor industry closely follows closely and its projects the need for several technology generations. The package must be capable of meeting these projections in order for it to be successful. This section reviews some of the current interconnect technology. Wire bonding [15] as shown in Figure 2.1, is generally considered as one of the most simple, cost-effective and flexible interconnect technology. The devices on the silicon die are (gold or aluminum) wire bonded to electrically connect from the chip to the wire bond pads on the periphery. However, the disadvantages of wire bonding are the slow rate, large pitch and long interconnect length and hence this will not be suitable for high I/O application. Instead of wires in the wire bonding, tape automated bonding (TAB) is an interconnect technology using a prefabricated perforated polyimide film, with copper leads between chip and substrate. The advantage of this technology is the high throughput and the high lead count. However, it is limited by the high initial costs for tooling. An alternative to peripheral interconnect technology is the area-array solution, as shown in Figure 2.3, that access the unused area by using the area under the chip. In area-array packaging, the chip has an array of solder bumps that are joined to a substrate. Under-fill is then fills the gap between the chip and substrate to enhance mechanical adhesion. This technology gives the highest packaging density methods and best electrical characteristics of all the avaiable interconnection technology. However, not only is its initial cost is high, it requires a very demanding technology to establish and operate. With the need for higher I/O density, compliant interconnects have been developed to satisfy the mechanical requirements of high performance micron sized interconnects. The basic idea is to reduce shear stress experienced by the interconnects through increasing their height or decreasing of its shear modulus (i.e. increases in their compliant) and hence the name compliant interconnects. Some of recent research in compliant interconnects include Tesseras Wide Area Vertical Expansion, Form Factors Wire on Wafer and Georgia Institute of Technologys Helix interconnects [17-19] as shown in Figure 2.4. Although compliant interconnects can solve the problem of mechanical reliability issue, they are done at the expense of the electrical performance. Since there is a need to reduce the packages parasitic through a decrease line delays, there is a need to minimize the electrical connection length in order to increase the system working frequency. Hence, compliant interconnect may not meet the high electrical frequency requirements of future devices. Figure 2.4: (a) Wide Area Vertical Expansion, (b) Wire on Wafer and (c) G-Helix [17-19] Lead and lead-free solders typically fail mechanical when scaled down to less than to a pitch of 100 mm. Compliant interconnections, on the other hand, do not meet the high frequency electrical requirements. The Microsystems Packaging Research Center at Georgia institute of Technology had demonstrated the feasibility of using re-workable nanostructure interconnections. Aggarwal et al [20] had show that nanostructured nickel interconnections, through a Flip Chip test vehicle, was able to improve the mechanical reliability while maintaining the shortest electrical connection length. However, the main disadvantages of this method was the significant signal loss at high frequency signal of nanocrystalline nickel [21]. As discussed above, nanostructure interconnects technology is the most promising interconnect technology to best meet the stringent mechanical and electrical requirement of next generation devices. However, there is a need of an alternate materials and a sensible choice of materials in this case would be nanocrystalline copper for its high strength material with superior electrical conductivity. Hence, it would be beneficial to use nanocrystalline-copper as material for the nanostructure interconnects. Due to the tendency for the grain to grow, there is a need to stabilize the grain growth in nanocrystalline copper before using it could be considered as a potential candidate for nanostructure interconnect. 2.2 Nanocrystalline material Nanocrystalline materials are polycrystalline materials with an average grain size of less than 100 nm [22]. Over the past decade , new nanocrystalline or nanostructured materials with key microstructural length scales on the order of a few tens of nanometers has been gaining a lot of interest in the material science research society. This is mainly due to its unique and superior properties, as compared to their microcrystalline counterparts which includes increased strength [22] and wear resistance [23]. These unique properties are due to the large volume fraction of atoms at or near the grain boundaries. As a result, these materials have unique properties that are representative of both the grain boundary surface characteristics and the bulk. Recent advances in synthesis and processing methodology for producing nanocrystalline materials such as inert gas condensation [24], mechanical milling [25, 26], electro-deposition [27], and severe plastic deformation [28] have made it possible to produce sufficient nanocrystalline materials for small scale application. 2.2.1 Synthesis Inert gas condensation, the first method used to synthesis bulk nanocrystalline [29], consists of evaporating a metal inside a high-vacuum chamber and then backfilling the chamber with inert gas [30]. These evaporated metal atoms would then collide with the gas atoms, causing them to lose kinetic energy and condenses into powder of small nano-crystals. These powders are then compacted under high pressure and vacuum into nearly fully dense nanocrystalline solids. The grain size distribution obtained from this method is usually very narrow. However, the major draws back of this method are its high porosity levels and imperfection bonding. Grain coarsening also occurs due to the high temperature during the compaction stage [31]. Mechanical milling consists of heavy cyclic deformation in powders until the final composition of the powders corresponds to a certain percentages of the respective initial constituents [25, 26]. A wide grain size distribution is obtained by this method. This technique is a popular method to prepare nanocrystalline materials because of its applicability to any material and simplicity. However, their main drawback includes contamination and grain coarsening during the consolidation stage. Electro-deposition consists of using electrical current to reduce cations of a desired material from a electrolyte solution and coating a conductive object on the substrate. Electro-deposition has many advantages over processing techniques and this includes its applicability to a wide variety of materials, low initial capital investment requirements and porosity-free finished products without a need for consolidation processing [27]. Furthermore, Shen et al. [32] and Lu et al.[33] had recently show that the right electro-deposition condition can produce a highly twinned structure which leads to enhanced ductility. The main drawback of this method is it is the difficulty to achieve high purity. Severe plastic deformation, such as high-pressure torsion, equal channel angular extrusion (ECAE), continuous confined shear straining and accumulative roll-bonding, uses extreme plastic straining to produce nanocrystalline materials by mechanisms such as grain fragmentation, dynamic recovery, and geometric re-crystallization [34]. It is the only technology that transformed conventional macro-grained metals directly into nanocrystalline materials without the need of potentially hazardous nano-sized powders. This is achieved by introducing very high shear deformations into the material under superimposed hydrostatic pressure. Two of the most commonly used methods are high-pressure torsion and ECAE [35]. In the study of the effect of ECAE on the microstructure of nanocrystalline copper, Dalla Torre et al [36] observed that the grains become more equi-axial and randomly orientation as the number of passes increases, as shown in Figure 2.5 Figure 2.5: Microstructure of ECAE copper subjected to (a) 1 passes (b) 2 passes (c) 4 passes (d) 8 passes (e) 12 passes and (f) 16 passes [36] 2.2.2 Mechanical Behavior of nanocrystalline materials Due to the small grain size and high volume fraction of grain boundaries, nanocrystalline materials exhibit significantly different properties and behavior as compared to their microcrystalline counterpart. The structure and mechanical behavior of nanocrystalline materials has been the subject of a lot of researchers interests both experimentally [37-43] and theoretically [44-50]. This section reviews the principal mechanical properties and behavior of nanocrystalline materials. 2.2.2.1 Strength and ductility Recent studies of nanocrystalline metals have shown that there is a five to ten fold increases in the strength and hardness as compared to their microcrystalline state [7, 36, 37, 51, 52]. This increase in the strength is due to the presence of grain boundaries impeding the nucleation and movement of dislocations. Since decreasing grain boundary size increases the number of barrier and the amount of applied stress necessary to move a dislocation across a grain boundary, this resulted in a much higher yield strength. The inverse relationship between grain size and strength is characterized by the Hall-Petch relationship [53, 54] as shown in equation (2.1). Eq (2.1) In equation (2.1), s is the mechanical strength, k is a material constant and d is the average grain size. Hence, nanocrystalline materials are expected to exhibit higher strength as compared to their microcrystalline counterpart. Figure 2.6 and Figure 2.7 show the summary of hardness and yield strength from tensile test that are reported in the literature. Indeed, hardness and yield strength of copper with a grain size of 10nm (3GPa) can be one order higher than their microcrystalline counterpart. To the larger specimens. Derivation from Hall-Petch relationship begins as the grain size approaches 30nm where the stresses needed to activate the dislocation multiplication via Frank-Read sources within the grains are too high and the plastic deformation is instead accommodated by grain boundaries sliding and migration.[12]. Furthermore, as the grain size reduces, the volume fraction of the grain boundaries and the triple points increases. Material properties will be more representative of the grain boundary activity [64] and this will resulting the strength to be inversely proportional to grain size instead of square roots of the grain size as predicted by Hall Petch relation [65]. Further reduction in the grain size will result in grain boundaries processes controlling the plastic deformation and reverse Hall-Petch effect, where the materials soften, will take place. Although sample defects had been account for the earlier experimental observation of reverse Hall-Petch effect[24], Swygenhoven et al [66] and Schiotz et al [47], using molecular simulation, was able to showed that nanocrystalline copper had the highest strength (about 2.3GPa ) at a grain size of 8nm and 10-15nm respectively. Conrad et al [67] pointed out that below this critical grain size, the mechanisms shifted to grain boundary-mediated from dislocation-mediated plasticity and this causes the material to become dependent on strain rate, temperature, Taylor orientation factor and presence of the type of dislocation. The yield stress of nanocrystalline copper was highly sensitive to strain rate even though it is a fcc materials. The strain rate sensitivity, m, in equation 2.2 a engineering parameter which measured the dependency of the strain rate and Figure 2.8 shows a summary of m as a function of grain size for copper specimen in the literature [51, 68-70]. Due to high localized dislocation activities at the grain boundaries which results in enhanced strain rate sensitivities in nanocrystalline materials, m increases drastically when the grain size is below 0.1 mm as shown in Figure 2.8. (2.2) Room temperature strain rate sensitivity was found to dependent on dislocation activities and grain boundaries diffusion [52, 71, 72]. Due to the negligible lattice diffusion at room temperature, the rate limiting process for microcrystalline copper was the gliding dislocation to cutting through forest dislocation, resulting in low strain rate sensitivities. However, due to the increasing presence of obstacles such as grain boundaries for nanocrystalline materials, the rate limiting process for smaller grain size was the interaction of dislocation and the grain boundaries, which is strain rate and temperature dependence. By considering the length scale of the dislocation and grain boundaries interaction, Cheng et al [52] proposed the following model for strain rate sensitivities . (2.3) z is the distance swept by the dislocation during activation, r is the dislocation density and a, a and b are the proportional factors. With this model, they will be able to predict higher strain rate sensitivities for nanocrystalline material produced by severe plastic deformation as compared to other technique. Since the twin boundaries in nanocrystalline or ultra fine grain copper served as a barriers for dislocation motion and nucleation which led to highly localized dislocations near the twin boundaries, the strain rate sensitivity of copper with high density of coherent twin boundaries was found to be higher than those without any twin boundaries [33]. Lastly, the increase enhanced strain rate sensitivity in nanocrystalline copper had been credited for it increases in strength and ductility. For example, Valiev et al [60] credited the enhanced strain rate sensitivity of 0.16 for the high ductility. In addition to a strong dependency on the strain rate, strength in nanocrystalline materials was also highly dependent on the temperature. Wang et al [73] observed that the yield strength for ultra fine grain copper with a grain size of 300nm increases from approximately 370MPa to 500MPa when the temperature reduces from room temperature to 77k. The authors attributed this increase in yield strength due to the absence of additional thermal deformation processes at 77k. This is consistent with Huang et al [74] observation where the temperature dependence of nanocrystalline copper with an increase in hardness of nanocrystalline copper with lowering the temperature is noted Ductility is another important characteristic of nanocrystalline materials. In microcrystalline materials, a reduction in grain size will increase the ductility due to the presence of grain boundaries acting as effective barriers to the propagation of micro-cracks[75]. However, nanocrystalline copper showed a lower strain to failure than that of their microcrystalline counterparts and this lacks in ductility was attributed to the presence of processing defects [76]. Recent advanced in processing of nanocrystalline materials offer materials with fairly good ductility in additional to ultra-high strength. Lu et al [10] reported that nanocrystalline copper with minimal flaw produced via electro-deposition had an elongation to fracture of 30%. Furthermore, Youssef et al [77] observed a 15.5% elongation to failure for defect free nanocrystalline copper produced via mechanical milling. Hence, it was possible for nanocrystalline copper to be both strong and ductile if the processing artifacts are minimized. The failure are usually consists of dimples several time larger than their grain size was normally found on the failure morphology of nanocrystalline materials and Kumar et al [78] presented the following model for initiation and hence the eventual failure of nanocrystalline materials. Furthermore, the presence of shear region was found to be due to shear localization since the ratio of strain hardening rate to prevailing stress was usually small [79, 80]. Figure 2.9: Schematic illustration of fracture in nanocrystalline material postulated by Kumar et al [78] 2.2.2.2 Creeps Nanocrystalline materials are expected to creep during room temperature. This is because Due to the higher fraction of grain boundaries and triple junctions, self diffusivity of nanocrystalline material had been shown to increase by an order of three as compared to microcrystalline copper [81]. Since creep behavior was dependent on grain size and diffusivity, with creep rate increases with an increase in diffusivity or a decrease in grain size, the creep temperature for nanocrystalline copper was known to be a small fraction of melting temperature (about 0.22 of its melting points). Furthermore, since creep had always been cited as one of the reason for grain size softening in nanocrystalline materials, creeps were other important mechanical properties of nanocrystalline materials that had been gaining a lot of researchers attention. Due to the high volume fraction of grain boundaries and enhanced diffusivity rate Model for Predicting Fatigue Life of Nanomaterials Model for Predicting Fatigue Life of Nanomaterials Introduction In the past, the primary function of micro-systems packaging was to provide input/output (I/O) connections to and from integrated circuits (ICs) and to provide interconnection between the components on the system board level while physically supporting the electronic device and protecting the assembly from the environment. In order to increase the functionality and the miniaturization of the current electronic devices, these IC devices have not only incorporated more transistors but have also included more active and passive components on an individual chip. This has resulted in the emerging trend of a new convergent system[1] Currently, there are three main approaches to achieving these convergent systems, namely the system-on-chip (SOC), system-in-package (SIP) and system on package (SOP). SOC seeks to integrate numerous system functions on one silicon chip. However, this approach has numerous fundamental and economical limitations which include high fabrication costs and integration limits on wireless communications, which due to inherent losses of silicon and size restriction. SIP is a 3-D packaging approach, where vertical stacking of multi-chip modules is employed. Since all of the ICs in the stack are still limited to CMOS IC processing, the fundamental integration limitation of the SOC still remains. SOP on the other hand, seeks to achieve a highly integrated microminiaturized system on the package using silicon for transistor integration and package for RF, digital and optical integration[1] IC packaging is one of the key enabling technologies for microprocessor performance. As performance increases, technical challenges increase in the areas of power delivery, heat removal, I/O density and thermo-mechanical reliability. These are the most difficult challenges for improving performance and increasing integration, along with decreasing manufacturing cost. Chip-to-package interconnections in microsystems packages serve as electrical interconnections but often fail by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that integrated chip (IC) packages will have interconnections with I/O pitch of 90 nm by the year 2018 [2]. Lead-based solder materials have been used for interconnections in flip chip technology and the surface mount technology for many decades. The traditional lead-based and lead-free solder bumps will not satisfy the thermal mechanical requirement of these fine pitches interconnects. These electronic packages, even under normal operating conditions, can reach a temperature as high as 150C. Due to differences in the coefficient of thermal expansion of the materials in an IC package, the packages will experience significant thermal strains due to the mismatch, which in turn will cause lead and lead-free solder interconnections to fail prematurely. Aggarwal et al [3] had modeled the stress experienced by chip to package interconnect. In his work, he developed interconnects with a height of 15 to 50 micrometre on different substrate using classic beam theory. Figure 1 shows the schematic of his model and a summary of some of his results. Although compliant intrerconect could reduces the stress experienced by the interconnect, it is still in sufficient. Chng et al. [4] performed a parametric study on the fatigue life of a solder column for a pitch of 100micrometre using a macro-micro approach. In her work, she developed models of a solder column/bump with a pad size of 50micrometre and heights of 50 micrometre to 200 micrometre. Table I shows a summary of some of her results. Table 1.1: Fatigue life estimation of solder column chip thickness (micrometre) 250 640 640 640 board CTE (ppm/K) 18 18 10 5 solder column height (micrometre) Fatigue life estimation/cycle) 50 81 N.A 171 3237 100 150 27 276 3124 150 134 31 518 4405 200 74 38 273 5772 It can be seen from Table 1.1 that the fatigue lives of all solder columns are extremely short. Apart from the 5ppm/K board where there is excellent CTE matching, the largest fatigue life of the solder column is only about 518 cycles. As expected, the fatigue life increases significantly when the board CTE decreases from 18ppm/K to 10ppm/K and as the height increases from 50micrometre to 200micrometre.This is mainly due to the large strain induced by the thermal mismatch as shown in Figure 1.2. The maximum inelastic principal strain was about 0.16 which exceeds the maximum strain that the material can support. Although the fatigue life of the chip to package interconnection can be increases by increasing the interconnects height, it will not be able to meet the high frequency electrical requirements of the future IC where they need to be operating at a high frequencies of 10-20 GHz and a signal bandwidth of 20 Gbps, By definition, nanocrystalline materials are materials that have grain size less than 100nm and these materials are not new since nanocrystalline materials have been observed in several naturally-occurring specimens including seashells, bone, and tooth enamel [5, 6]. However, the nanocrystalline materials have been attracting a lot of research interest due to its superior mechanical and electrical properties as compared to the coarse-grained counterpart. For example, the nano-crystalline copper has about 6 times the strength of bulk copper [7]. Furthermore, the improvement in the mechanical properties due to the reduction in grain size has been well-documented. Increase in strength due to the reduction in grain-size is predicted by the Hall-Petch relationship which has also been confirmed numerically by Swygenhoven et al [8] and was first demonstrated experimentally by Weertman [9]. The implantation of nanocrystalline copper as interconnect materials seems to be feasible from the processing viewpoint too. Copper has been used as interconnects materials since 1989 whereas nano-copper has also been widely processed using electroplating and other severe plastic deformation techniques in the past few years. For instance, Lu et al. [10] have reported electroplating of nano-copper with grain size less than 100 nm and electrical conductivity comparable to microcrystalline copper. Furthermore, Aggarwal et al [11] have demonstrated the feasibility of using electrolytic plating processes to deposit nanocrystalline nickel as a back-end wafer compatible process. However, there are certain challenges regarding implantation of nanocrystalline copper as interconnects materials. As discussed above, nanocrystalline copper have a high potential of being used as the next generation interconnect for electronic packaging. However, it is vital to understand their material properties, deformation mechanisms and microstructures stability. Although the increase in strength due to the Hall-Petch relationship which has also been confirmed numerically and experimentally by Weertman [9], the improvement in the fatigue properties is not well documented and no model has been established to predict/characterize these nano materials in interconnection application; conflicting results regarding the fatigue properties have also been reported. Kumar et al [12] reported that for nano-crystalline and ultra-fine crystalline Ni, although there is an increase in tensile stress range and the endurance limit, the crack growth rate also increases. However, Bansal et al. [7] reported that with decreasing grain size, the tensile stress range increases but the crack growth rate decreases substantially at the same cyclic stress intensity range. Thus, nanostructured materials can potentially provide a solution for the reliability of low pitch interconnections. However, the fatigue resistance of nanostructured interconnections needs to be further investigated. Since grain boundaries in polycrystalline material increases the total energy of the system as compare to perfect single crystal, it will resulted in a driving force to reduce the overall grain boundary area by increasing the average grain size. In the case of nanocrystalline materials which have a high volume fraction of grain boundaries, there is a huge driving force for grain to growth and this presented a presents a significant obstacle to the processing and use of nanocrystalline copper for interconnect applications. Millet et al [13] have shown, though a series of systematic molecular dynamics simulations, grain growth in bulk nanocrystalline copper during annealing at constant temperature of 800K can be impeded with dopants segregated in the grain boundaries regions. However, it has been observed that stress can trigger grain growth in nanocrystalline materials [14] and there is no literature available on impeding stress assisted grain growth. There is an impending need to investigate the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth Dissertation Objectives The goal of present project is to develop a model for the fatigue resistance of nano-materials that have been shown to have superior fatigue resistance. Accordingly, the following research objectives are proposed. Develops a model for predicting fatigue life of nanostructured chip-to-package copper interconnections Develops a fundamental understanding on the fatigue behavior of nanocrystalline copper for interconnect application Addresses the issue on the stability of nanocrystalline materials undergoing cyclic loading Overview of the Thesis The thesis is organized so that past research on nanocrystalline materials forms the basis of the understanding and new knowledge discovered in this research. Chapter 2 reviews much of the pertinent literature regarding nanocrystalline materials, including synthesis, deformation mechanisms, and grain growth. Chapter 3 describes a detailed overview of the technical aspects of the molecular dynamics simulation method including inter-atomic potentials, time integration algorithms, the NVT NPT, and NEPT ensembles, as well as periodic boundary conditions and neighbor lists. Include in this chapter is the algorithms for creating nanocrystalline materials used in this dissertations.. Chapter 4 describes the simulation procedure designed to investigate and develop the long crack growth analysis. The results of the long crack growth analysis will be presented at the end of Chapter 4. Chapter 5 presents the result and discussion on mechanical behavior of single and nanocrystalline copper subjected to monotonic and cyclic loading whereas Chapter 6 presents the result and discussion on the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth. Finally, conclusions and recommendations for future work are presented in Chapter 5. Chapter 2 This chapter offers an expanded summary of the literature published with regards to the fabrication methods, characterization, and properties of nanocrystalline materials in addition to a description of existing interconnect technology. 2.1 Off-Chip Interconnect Technologies Chip-to-package interconnections in microsystems packages serve as electrical interconnections but they will often failed by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that interconnections of integrated chip (IC) packages will have a I/O pitch of 90 nm by the year 2018 [2]. The International Technology Roadmap for Semiconductors (ITRS) roadmap is a roadmap that semiconductor industry closely follows closely and its projects the need for several technology generations. The package must be capable of meeting these projections in order for it to be successful. This section reviews some of the current interconnect technology. Wire bonding [15] as shown in Figure 2.1, is generally considered as one of the most simple, cost-effective and flexible interconnect technology. The devices on the silicon die are (gold or aluminum) wire bonded to electrically connect from the chip to the wire bond pads on the periphery. However, the disadvantages of wire bonding are the slow rate, large pitch and long interconnect length and hence this will not be suitable for high I/O application. Instead of wires in the wire bonding, tape automated bonding (TAB) is an interconnect technology using a prefabricated perforated polyimide film, with copper leads between chip and substrate. The advantage of this technology is the high throughput and the high lead count. However, it is limited by the high initial costs for tooling. An alternative to peripheral interconnect technology is the area-array solution, as shown in Figure 2.3, that access the unused area by using the area under the chip. In area-array packaging, the chip has an array of solder bumps that are joined to a substrate. Under-fill is then fills the gap between the chip and substrate to enhance mechanical adhesion. This technology gives the highest packaging density methods and best electrical characteristics of all the avaiable interconnection technology. However, not only is its initial cost is high, it requires a very demanding technology to establish and operate. With the need for higher I/O density, compliant interconnects have been developed to satisfy the mechanical requirements of high performance micron sized interconnects. The basic idea is to reduce shear stress experienced by the interconnects through increasing their height or decreasing of its shear modulus (i.e. increases in their compliant) and hence the name compliant interconnects. Some of recent research in compliant interconnects include Tesseras Wide Area Vertical Expansion, Form Factors Wire on Wafer and Georgia Institute of Technologys Helix interconnects [17-19] as shown in Figure 2.4. Although compliant interconnects can solve the problem of mechanical reliability issue, they are done at the expense of the electrical performance. Since there is a need to reduce the packages parasitic through a decrease line delays, there is a need to minimize the electrical connection length in order to increase the system working frequency. Hence, compliant interconnect may not meet the high electrical frequency requirements of future devices. Figure 2.4: (a) Wide Area Vertical Expansion, (b) Wire on Wafer and (c) G-Helix [17-19] Lead and lead-free solders typically fail mechanical when scaled down to less than to a pitch of 100 mm. Compliant interconnections, on the other hand, do not meet the high frequency electrical requirements. The Microsystems Packaging Research Center at Georgia institute of Technology had demonstrated the feasibility of using re-workable nanostructure interconnections. Aggarwal et al [20] had show that nanostructured nickel interconnections, through a Flip Chip test vehicle, was able to improve the mechanical reliability while maintaining the shortest electrical connection length. However, the main disadvantages of this method was the significant signal loss at high frequency signal of nanocrystalline nickel [21]. As discussed above, nanostructure interconnects technology is the most promising interconnect technology to best meet the stringent mechanical and electrical requirement of next generation devices. However, there is a need of an alternate materials and a sensible choice of materials in this case would be nanocrystalline copper for its high strength material with superior electrical conductivity. Hence, it would be beneficial to use nanocrystalline-copper as material for the nanostructure interconnects. Due to the tendency for the grain to grow, there is a need to stabilize the grain growth in nanocrystalline copper before using it could be considered as a potential candidate for nanostructure interconnect. 2.2 Nanocrystalline material Nanocrystalline materials are polycrystalline materials with an average grain size of less than 100 nm [22]. Over the past decade , new nanocrystalline or nanostructured materials with key microstructural length scales on the order of a few tens of nanometers has been gaining a lot of interest in the material science research society. This is mainly due to its unique and superior properties, as compared to their microcrystalline counterparts which includes increased strength [22] and wear resistance [23]. These unique properties are due to the large volume fraction of atoms at or near the grain boundaries. As a result, these materials have unique properties that are representative of both the grain boundary surface characteristics and the bulk. Recent advances in synthesis and processing methodology for producing nanocrystalline materials such as inert gas condensation [24], mechanical milling [25, 26], electro-deposition [27], and severe plastic deformation [28] have made it possible to produce sufficient nanocrystalline materials for small scale application. 2.2.1 Synthesis Inert gas condensation, the first method used to synthesis bulk nanocrystalline [29], consists of evaporating a metal inside a high-vacuum chamber and then backfilling the chamber with inert gas [30]. These evaporated metal atoms would then collide with the gas atoms, causing them to lose kinetic energy and condenses into powder of small nano-crystals. These powders are then compacted under high pressure and vacuum into nearly fully dense nanocrystalline solids. The grain size distribution obtained from this method is usually very narrow. However, the major draws back of this method are its high porosity levels and imperfection bonding. Grain coarsening also occurs due to the high temperature during the compaction stage [31]. Mechanical milling consists of heavy cyclic deformation in powders until the final composition of the powders corresponds to a certain percentages of the respective initial constituents [25, 26]. A wide grain size distribution is obtained by this method. This technique is a popular method to prepare nanocrystalline materials because of its applicability to any material and simplicity. However, their main drawback includes contamination and grain coarsening during the consolidation stage. Electro-deposition consists of using electrical current to reduce cations of a desired material from a electrolyte solution and coating a conductive object on the substrate. Electro-deposition has many advantages over processing techniques and this includes its applicability to a wide variety of materials, low initial capital investment requirements and porosity-free finished products without a need for consolidation processing [27]. Furthermore, Shen et al. [32] and Lu et al.[33] had recently show that the right electro-deposition condition can produce a highly twinned structure which leads to enhanced ductility. The main drawback of this method is it is the difficulty to achieve high purity. Severe plastic deformation, such as high-pressure torsion, equal channel angular extrusion (ECAE), continuous confined shear straining and accumulative roll-bonding, uses extreme plastic straining to produce nanocrystalline materials by mechanisms such as grain fragmentation, dynamic recovery, and geometric re-crystallization [34]. It is the only technology that transformed conventional macro-grained metals directly into nanocrystalline materials without the need of potentially hazardous nano-sized powders. This is achieved by introducing very high shear deformations into the material under superimposed hydrostatic pressure. Two of the most commonly used methods are high-pressure torsion and ECAE [35]. In the study of the effect of ECAE on the microstructure of nanocrystalline copper, Dalla Torre et al [36] observed that the grains become more equi-axial and randomly orientation as the number of passes increases, as shown in Figure 2.5 Figure 2.5: Microstructure of ECAE copper subjected to (a) 1 passes (b) 2 passes (c) 4 passes (d) 8 passes (e) 12 passes and (f) 16 passes [36] 2.2.2 Mechanical Behavior of nanocrystalline materials Due to the small grain size and high volume fraction of grain boundaries, nanocrystalline materials exhibit significantly different properties and behavior as compared to their microcrystalline counterpart. The structure and mechanical behavior of nanocrystalline materials has been the subject of a lot of researchers interests both experimentally [37-43] and theoretically [44-50]. This section reviews the principal mechanical properties and behavior of nanocrystalline materials. 2.2.2.1 Strength and ductility Recent studies of nanocrystalline metals have shown that there is a five to ten fold increases in the strength and hardness as compared to their microcrystalline state [7, 36, 37, 51, 52]. This increase in the strength is due to the presence of grain boundaries impeding the nucleation and movement of dislocations. Since decreasing grain boundary size increases the number of barrier and the amount of applied stress necessary to move a dislocation across a grain boundary, this resulted in a much higher yield strength. The inverse relationship between grain size and strength is characterized by the Hall-Petch relationship [53, 54] as shown in equation (2.1). Eq (2.1) In equation (2.1), s is the mechanical strength, k is a material constant and d is the average grain size. Hence, nanocrystalline materials are expected to exhibit higher strength as compared to their microcrystalline counterpart. Figure 2.6 and Figure 2.7 show the summary of hardness and yield strength from tensile test that are reported in the literature. Indeed, hardness and yield strength of copper with a grain size of 10nm (3GPa) can be one order higher than their microcrystalline counterpart. To the larger specimens. Derivation from Hall-Petch relationship begins as the grain size approaches 30nm where the stresses needed to activate the dislocation multiplication via Frank-Read sources within the grains are too high and the plastic deformation is instead accommodated by grain boundaries sliding and migration.[12]. Furthermore, as the grain size reduces, the volume fraction of the grain boundaries and the triple points increases. Material properties will be more representative of the grain boundary activity [64] and this will resulting the strength to be inversely proportional to grain size instead of square roots of the grain size as predicted by Hall Petch relation [65]. Further reduction in the grain size will result in grain boundaries processes controlling the plastic deformation and reverse Hall-Petch effect, where the materials soften, will take place. Although sample defects had been account for the earlier experimental observation of reverse Hall-Petch effect[24], Swygenhoven et al [66] and Schiotz et al [47], using molecular simulation, was able to showed that nanocrystalline copper had the highest strength (about 2.3GPa ) at a grain size of 8nm and 10-15nm respectively. Conrad et al [67] pointed out that below this critical grain size, the mechanisms shifted to grain boundary-mediated from dislocation-mediated plasticity and this causes the material to become dependent on strain rate, temperature, Taylor orientation factor and presence of the type of dislocation. The yield stress of nanocrystalline copper was highly sensitive to strain rate even though it is a fcc materials. The strain rate sensitivity, m, in equation 2.2 a engineering parameter which measured the dependency of the strain rate and Figure 2.8 shows a summary of m as a function of grain size for copper specimen in the literature [51, 68-70]. Due to high localized dislocation activities at the grain boundaries which results in enhanced strain rate sensitivities in nanocrystalline materials, m increases drastically when the grain size is below 0.1 mm as shown in Figure 2.8. (2.2) Room temperature strain rate sensitivity was found to dependent on dislocation activities and grain boundaries diffusion [52, 71, 72]. Due to the negligible lattice diffusion at room temperature, the rate limiting process for microcrystalline copper was the gliding dislocation to cutting through forest dislocation, resulting in low strain rate sensitivities. However, due to the increasing presence of obstacles such as grain boundaries for nanocrystalline materials, the rate limiting process for smaller grain size was the interaction of dislocation and the grain boundaries, which is strain rate and temperature dependence. By considering the length scale of the dislocation and grain boundaries interaction, Cheng et al [52] proposed the following model for strain rate sensitivities . (2.3) z is the distance swept by the dislocation during activation, r is the dislocation density and a, a and b are the proportional factors. With this model, they will be able to predict higher strain rate sensitivities for nanocrystalline material produced by severe plastic deformation as compared to other technique. Since the twin boundaries in nanocrystalline or ultra fine grain copper served as a barriers for dislocation motion and nucleation which led to highly localized dislocations near the twin boundaries, the strain rate sensitivity of copper with high density of coherent twin boundaries was found to be higher than those without any twin boundaries [33]. Lastly, the increase enhanced strain rate sensitivity in nanocrystalline copper had been credited for it increases in strength and ductility. For example, Valiev et al [60] credited the enhanced strain rate sensitivity of 0.16 for the high ductility. In addition to a strong dependency on the strain rate, strength in nanocrystalline materials was also highly dependent on the temperature. Wang et al [73] observed that the yield strength for ultra fine grain copper with a grain size of 300nm increases from approximately 370MPa to 500MPa when the temperature reduces from room temperature to 77k. The authors attributed this increase in yield strength due to the absence of additional thermal deformation processes at 77k. This is consistent with Huang et al [74] observation where the temperature dependence of nanocrystalline copper with an increase in hardness of nanocrystalline copper with lowering the temperature is noted Ductility is another important characteristic of nanocrystalline materials. In microcrystalline materials, a reduction in grain size will increase the ductility due to the presence of grain boundaries acting as effective barriers to the propagation of micro-cracks[75]. However, nanocrystalline copper showed a lower strain to failure than that of their microcrystalline counterparts and this lacks in ductility was attributed to the presence of processing defects [76]. Recent advanced in processing of nanocrystalline materials offer materials with fairly good ductility in additional to ultra-high strength. Lu et al [10] reported that nanocrystalline copper with minimal flaw produced via electro-deposition had an elongation to fracture of 30%. Furthermore, Youssef et al [77] observed a 15.5% elongation to failure for defect free nanocrystalline copper produced via mechanical milling. Hence, it was possible for nanocrystalline copper to be both strong and ductile if the processing artifacts are minimized. The failure are usually consists of dimples several time larger than their grain size was normally found on the failure morphology of nanocrystalline materials and Kumar et al [78] presented the following model for initiation and hence the eventual failure of nanocrystalline materials. Furthermore, the presence of shear region was found to be due to shear localization since the ratio of strain hardening rate to prevailing stress was usually small [79, 80]. Figure 2.9: Schematic illustration of fracture in nanocrystalline material postulated by Kumar et al [78] 2.2.2.2 Creeps Nanocrystalline materials are expected to creep during room temperature. This is because Due to the higher fraction of grain boundaries and triple junctions, self diffusivity of nanocrystalline material had been shown to increase by an order of three as compared to microcrystalline copper [81]. Since creep behavior was dependent on grain size and diffusivity, with creep rate increases with an increase in diffusivity or a decrease in grain size, the creep temperature for nanocrystalline copper was known to be a small fraction of melting temperature (about 0.22 of its melting points). Furthermore, since creep had always been cited as one of the reason for grain size softening in nanocrystalline materials, creeps were other important mechanical properties of nanocrystalline materials that had been gaining a lot of researchers attention. Due to the high volume fraction of grain boundaries and enhanced diffusivity rate