Esterification

To synthesis ecstatically acid by stratification. Introduction: A pleasant, often fruity, odor is characteristic of some of the simpler esters. Ethyl butyrate smells similar to pineapples, the odor of n-propel acetate is reminiscent of pears and isopleths acetate has a strong banana fragrance. Esters are derivatives of the carboxylic acids and contain the following functional group: The synthesis of an ester can be accomplished in one of several ways. An stratification occurs when an alcohol and a carboxylic acid are reacted in the reserve of a mineral acid catalyst, such as sulfuric acid.Because these reactions result in an equilibrium mixture of both products and reactants, the reaction conditions must be manipulated in order to produce a reasonable yield. A large excess of one of the reactants can be used in the starting mixture or alternatively, one of the products can be removed as the reaction proceeds (as by a distillation), to shift the equilibrium to the right. Other synthet ic pathways to esters also exist. Acid chlorides react with alcohols to yield an ester and hydrochloric acid.A small amount of pyridine is usually deed to the reaction mixture to neutralize the resulting acid. Acid anhydride can also react with alcohols to produce esters. Unlike the reactions between carboxylic acids and alcohols, neither of these two methods for preparing esters results in an equilibrium mixture. Ecstatically acid, or aspirin, is one of the most widely used and versatile drugs known today. It was first synthesized by Charles von Gerhardt in 1 853 and was later patented by a German dye chemist named Frederica Brayer in 1893 who recognized its potential as an analgesic (pain reliever).Salicylic acid, a impotent of willow and poplar bark, had been used as a pain killer for centuries, but its highly acidic property caused irritation of the mucous membranes of the mouth and throat and also resulted in uncomfortable gastric pain. By transforming the acidic phenol functio nality into an ester group, the compound retained its analgesic properties but lost some of its irritating side- effects. In addition to relieving pain, aspirin is also an antipathetic (fever reducer) and an anti-inflammatory agent (used for arthritis). Like all drugs, aspirin also has some undesirable side effects which should be tote.When taken in large quantities (several grams per day), gastric problems can result. Its use has been implicated in Rexes syndrome, a brain disorder that can affect people under the age of 18. Some people are highly allergic to aspirin. Finally, aspirin interferes with platelets and affects normal blood clotting which can lead to hemorrhaging in extreme cases. However, its anticoagulant properties can also be used to advantage in preventing blood clots from forming in the arteries. Recent studies have shown that the consumption of one half of an aspirin tablet per day can help to prevent heart attacks and strokes.Aspirin can be synthesized by the stra tification of salicylic acid via reaction with acetic anhydride. A few drops of phosphoric acid are added to serve as a catalyst for the reaction. The use of acetic anhydride as a reactant, instead of acetic acid, results in a rapid and irreversible conversion of salicylic acid to ecstatically acid. Experimental Procedure: Synthesis of ecstatically acid 1 . A 400 ml beaker containing about 150 ml of water was heated to the boiling point on a hot plate. 2. 2 g of salicylic acid was weighed out and it was placed in a 100 ml conical flask. . 5 ml of acetic anhydride was added into the conical flask. . 5 drops of 85% phosphoric acid, HAPPY was added. The flask was swirled to mix the reactants and then it was clamped in the boiling water bath. It was heated for about 8 minutes. 5. The flask was removed carefully from the hot water bath and the hot plate was turned off. 2 ml of distilled water was added cautiously to the flask. The water will react with any unrelated acetic anhydride whic h remains. 6. Once the reaction between acetic anhydride and water had subsided, 40 ml Of water Was added to the flask. 7. The contents was allowed to cool at room temperature for minutes then the flask was placed in ice. . The contents was stirred with a glass rod periodically during this cooling period. The solid product was collected by vacuum filtration and it was washed with cooled water. 9. A small portion (spatula-tip full, 20-30 MGM) of this crude ecstatically acid was set aside. 10. To recitalist the ecstatically acid, it was transferred to a 100 ml conical flask and 10 ml of 95% ethanol was added. 1 1. The flask was heated slowly on a hot plate just until the aspirin completely dissolved. As soon as all of the solid has dissolved, the flask was removed from the hot plate. 12.Water was added to the solution in 5 ml portions, it was swirled after each addition, until a total of 40 ml of water has been added. 13. The flask was placed in an ice bath for 10 minutes to complete the crystallization. 14. The purified aspirin was collected by vacuum filtration. The crystals was washed in the funnel with ice-cold water. The vacuum was left on for a few minutes to air dry the purified aspirin, the crystals was then pressed between two pieces of filter paper to thoroughly dry them. 5. The mass, yield and melting point of dried aspirin were obtained. Results: Weight of salicylic acid used: 2. 0021 g Weight of watch glass: 20. 536 g Weight of watch glass t product: 21. 6651 g Weight of product: 1. 3115 g no. Of mole of salicylic acid: = 0. 01450 mol Volume Of acetic anhydride used 5 ml Density of acetic anhydride = 1. 082 g/ml Mass of acetic anhydride used = 1. 082 g/ml x 5 ml = 5. 41 g no. Of mole of acetic anhydride: – 0. 0530 mol = 3. 66>1 Since the mol of salicylic acid is smaller than the mol of acetic anhydride, salicylic acid is a limiting agent. Mol of salicylic acid produced 1 mol of ecstatically acid. 0. 01450 mol of salicylic acid produced 0. 014 50 mol of ecstatically acid. Theoretical weight of ecstatically acid: 0. 1450 mol x 180. 16 gnu-mol = 2. 6123 g Percentage yield: x 100% = 50. 20 % 50 % Melting point of aspirin: 138 – 140 co Discussion: Aspirin is an effective analgesic (pain reliever), antipathetic (fever reducer) and anti-inflammatory' agent and is one of the most widely used non-prescription drugs. The active ingredient in aspirin was found to be salicylic acid. The structure of salicylic acid is shown below. In this experiment, aspirin is formed from the reaction between salicylic acid and acetic anhydride through stratification. Aspirin can be made by reacting salicylic acid with acetic acid in the presence of an acid catalyst.The phenol group on the salicylic acid forms an ester with the carboxylic group on the acetic acid. However, this reaction is slow and has a relatively low yield. If acetic anhydride was used instead of acetic acid, the reaction will be much faster and has a higher yield (since ac etic anhydride is much more reactive than acetic acid). Therefore, we used acetic anhydride for shorten the period f stratification. In order for reaction to occur faster, phosphoric acid was added as a catalyst. Then the solution was being placed in the hot water bath to heat up and thus triggering the reaction between salicylic acid and acetic anhydride.The reaction was shown as below: In this experiment, the salicylic acid is the limiting reactant and the acetic anhydride is in excess. The addition of distilled water into the mixture after it is being removed from the water bath is to let the water react with the remaining acetic anhydride in the mixture which are still not being reacted. A vigorous reaction will occur as the decomposition of the excess acetic anhydride is exothermic. Once the decomposition of the excess acetic anhydride has completed, more water was added, forming completing the reaction.Now the solution contains two kinds of products, which are ecstatically aci d and acetic acid, according to the reaction shown below. The reason why acetic acid is dissolved in this process but not ecstatically acid was due to the hydrogen bonding of acetic acid can form with water while ecstatically acid cannot. This is due to the large carbon group maintained by ecstatically acid which caused it to have difficulties from forming hydrogen bond with water. The aspirin collected will then be purified by rationalizations. In this purification method, the crude aspirin will be dissolved in a small amount of warm ethanol.Water was then be added and the solution was cooled slowly in the ice bath and then chilled. The ecstatically acid will recitalist, and the solid impurities (unrelated salicylic acid) should remain dissolved in the solution. The solid aspirin will again be collected using vacuum filtration. Rationalizations was needed to obtain a pure product from the crude product. Therefore, this aspirin should be more pure than the original aspirin. The fina l product was left in air dry and weighed. The theoretical and percentage yield was calculated. The weight of ecstatically acid obtained was 1. 115 g while the percentage yield of product was 50%. Besides, the melting point of ecstatically acid we obtained was in the range of 1 38 – 140 By comparing these observed melting points with the literature value of 138 – CHIC for ecstatically acid, it was found that the values were exactly the same, indicating that both rodents were ecstatically acid( previously stated as ecstatically acid and acetic acid). The above reaction was an example of an organic synthesis called stratification. Stratification is the acid catcalled reaction of a carboxylic (-COHO) group and an -OH group of an alcohol or phenol to form a carboxylic ester.In the synthesis of aspirin, the -OH group is the phenol OH group attached to ring of the salicylic acid. The acetic group, ;COACH comes from acetic anhydride, and the reaction is catcalled by phosphori c acid, HAPPY. Salicylic acid has a higher priority as it has a benzene ring which s more stable than the open chain of acetic anhydride because it has more resonance. Salicylic acid reacts better with acetic anhydride than acetic acid, so acetic acid will provide the acetic group which will react with the alcoholic – OH group on the salicylic acid.The hydrogen ion from the hydroxyl group in the salicylic acid breaks away first, then combines with the oxygen which has a negative charge after acetic anhydride is broken into two parts, which are an alkyl carbonyl group and -?CHOC- group. This is how acetic acid is formed. Later on, the alkyl carbonyl group of acetic anhydride which now has positive charge due to the lack Of oxygen atom, connects to the oxygen atom which has a negative charge, lastly produced ecstatically acid as a neutral compound product.The mechanism of how an ecstatically acid formed from stratification reaction will be shown: Precaution steps: 1 . When hand ling phosphoric acid, students should be aware of spill it out because it is corrosive. 2. When adding water to the heated solution, students should be careful and added in small amount of water because it may splatter to the surroundings due to the vigorous reaction. 3. The elution was allowed to cool at room temperature before putting it into the ice bath for the process of crystallization in order to get crystals in a nicer form and in correct manner.

Alternative Methods to Obtain Stem Cells †Science Research

Alternative Methods to Obtain Stem Cells – Science Research Free Online Research Papers In 2005, the President’s Council on Bioethics convened to discuss alternative means of deriving pluripotent stem cells. Due to the nature of a blastocyst’s cellular organization, the original procedure to cultivate pluripotent stem cells lines involved the desegregation of blastomeres in developing embryos that necessitated their untimely death1. This process at its inception brought into question the ethics of using pluripotent stem cells derived from embryos, as it meant taking life to save life. This controversy was brought to the attention of the general public and resulted in, then, President George W. Bush delivering a speech on August 9, 2001 announcing his policy decision to â€Å"allow [scientists] to explore the promise and potential of stem cell research without crossing a fundamental moral line, by providing taxpayer funding that would sanction or encourage further destruction of human embryos that have at least the potential for life.† In effect, he would allow scientific research to continue to be performed on stem cells lines that had been derived previous to that date, but would not support federally funding new stem cell lines2. Stem cell research made several minor advancements in spite of this policy, but the governmental limitations frustrated many scientists who looked to stem cells as a vast new area to be explored. Thus, the council’s main objective was to find a morally preferable way to derive healthy pluripotent cells3. Many alternatives were discussed at length, but one, I believe, has the most potential for future application. This alternative process of deriving pluripotent stem cells is the Landry-Zucker Proposal. Donald Landry and Howard Zucker of Columbia University, in their landmark review of the situation, advocated for the derivation of pluripotent stem cell lines using blastomeres surgically removed from organismically dead embryos. Drawing upon court rulings and legislative acts, they surmised that an embryo could be technically classified as dead once the cells lost the ability of â€Å"continued and integrated cellular division, growth, and differentiation.1† The idea is that even though the embryo has lost the opportunity for further development, some healthy individual cells remain and can potentially be harvested for cultivation. In some ways, this proposal is analogous to the removal of organs from a deceased human adult3. Modern day IVF clinics contain a vast resource of healthy pluripotent stem cells that are currently left unutilized. Dr. Laverge at the Department of Obstetrics and Gynaecology at the University Hospital in Belgium found a significant percentage of embryos preserved by cryogenic storage in IVF clinics do not continue cellular cleavage after being thawed; or lack the capacity for continued growth and development. There is a host of articles relating to scientists concerns that the reason behind the cessation of cleavage is solely chromosomal abnormalities1 3. This raises a serious issue of practicality as only healthy, diploid blastomeres can be used to derive normal functioning pluripotent stem cells. Addressing this issue, Dr. Laverge’s study found that approximately 11 percent of the non-cleaving embryos do not contain chromosomal abnormalities and would be suitable for pluripotent stem cell removal4. In a separate experiment by Dr. Alikani of the Institute for Reproductive Medicine and Science of Saint Barnabas, 107 non-viable embryos were used to extract 247 individual cells. 33% of these cells were found to differentiate and continue normal cellular activity when placed in a living host embryo5. This constitutes a major supply of healthy stem cells without the ethical issues surrounding the extraction procedure. The Landry-Zucker proposition circumvents the ethical issues of harming human embryos during the extraction process (as they are already dead) but new ethical issues surface due to critics concerns that IVF clinics would intentionally harm embryos to increase the number available for stem cell extraction. The two Columbia professors addressed this concern by stipulating that only embryos originally created with reproductive intent, that were thought healthy enough to be kept alive in cryogenic storage, and that, after thawing, turned out to be dead could be used to derive cell cultures1. Regulatory boards could be created to ensure these guidelines were being met, and thus, no intentionally destroyed embryos would be used for research purposes. Another practical concern resulting from this proposition is the determination of embryo death. A study analyzing the success rates of cryostorage on embryos found that 90% of recently thawed embryos that displayed no cleavage after 24 hours did not cleave any further4. This allows for an approximation system, but more exact (and less time consuming) methods are needed. The Landry-Zucker proposal suggests further studies in biochemical markers that initiate spontaneous embryo death1. If these markers were to be found, there would be a reliable way for determining embryonic death and therefore less controversy in its designation. The reason the Landry-Zucker proposal has not been widely implemented could be a result of the significant investment of initial capital (both human resources and instrumentation) required to make the leap from current IVF policies to the ones proposed. Private companies have to weigh the pros and cons of using blastomeres derived from organismically dead embryos rather than the stem-cell lines derived before the designated deadline of August 9, 2001. Stem cells obtained from the spontaneously dead embryos must first be surgically removed, cultured, and then karyotyped to determine whether the new cell colony originated from a blastomere with genetic abnormalities (such as aneuploidy). This process obviously requires time and money that would not be needed if they were taken from the original stem cells. However, as former President Bush stated, his policy was set forth to avoid the further destruction of human embryos that have the potential for life3. As the embryos in the Landry- Zucker Proposal are from spontaneously dead embryos, the procedure cannot be said to harm them. This creates a loophole in which government funding may be acquired, offsetting the initial costs while remaining a viable way to acquire diploid blastomeres without the disruption to embryonic life. A number of potential uses for human embryonic stem cells have been championed ever since a method for preparing them was discovered in 19986. Even if pluripotent stem cells relieve none of the numerous diseases scientists claim, research on these unspecialized cells will provide an invaluable understanding of the processes of cellular differentiation. Scientists must be given use of these cells to further our understanding of ourselves and our humble embryonic origins. This knowledge, however, should be acquired through procedures that respect the sanctity of life. I believe the Landry-Zucker Proposal is an ethically sound way to cultivate future pluripotent stem cell lines. References: 1. Landry, D.W., Zucker, H.A. (2004). Embryonic death and the creation of human embryonic stem cells. Journal of Clinical Investigation. 114(9), 1184-1186. (Google Scholar: Landry-Zucker Proposal, Alternative stem cells) 2. Wertz, D.C. (2002). Embryo and stem cell research in the United States: history and politics. Gene Therapy, 9, 674?678. (Google Scholar: History of stem cells in United States, George W. Speech on stem cells) 3. The Presidents Council on Bioethics. (2005). White paper: alternative sources of pluripotent stem cells. Washington, DC: U.S. Government Printing Office. (Google Scholar: Alternative sources of stem cells) 4. Laverge, H, et al. (1998). Fluorescent in-situ hybridization on human embryos showing cleavage arrest after freezing and thawing. Human Reproduction, 13, 425-429. (Google Scholar: Freezing and thawing, cryostorage, IVF clinics, human embryos) 5. Alikani, M, Willadsen, S. (2002). Human blastocysts from aggregated mononucleated cells of two or more non-viable zygote-derived embryos. Reprod. Biomed. Online, 5, 56-58. (Google Scholar: human embryos, non-viable, mortality rate, IVF clinics) 6. Thomson, JA, et al. (1998). Embryonic stem cell lines derived from human blastocysts. Science, 282, 1145-1147. (Google Scholar: Original method for viable human stem cells, blastomeres) Research Papers on Alternative Methods to Obtain Stem Cells - Science ResearchGenetic EngineeringInfluences of Socio-Economic Status of Married MalesAnalysis of Ebay Expanding into AsiaMoral and Ethical Issues in Hiring New EmployeesEffects of Television Violence on ChildrenResearch Process Part OneBionic Assembly System: A New Concept of SelfRelationship between Media Coverage and Social andPETSTEL analysis of IndiaOpen Architechture a white paper

The Freedom Writers Diary Essays

The Freedom Writers Diary Essays The Freedom Writers Diary Essay The Freedom Writers Diary Essay The Freedom Writers Essay- Chloe Taylor How are different cultures represented in Freedom Writers? What values and attitudes do we draw from the film and its background? Cultures are shown and exposed to us in various ways everyday. Different cultures are represented in different ways in the Western Society. In the movie Freedom Writers, we witness this cultural conflict on a first hand basis. Urban youths in Freedom Writers heavily rely on respect to judge others. They also judge based on each other’s cultural back ground. Later in the film, these same teenagers begin to value education and the sense of belonging in school, rather than belonging in gangs. Gangs and groups are a part of the Western Society that we have had to learn to accept in our lives. In the feature film Freedom Writers, we are shown gangs divided up into cultures and cultural backgrounds. This has built up a lot of tension between cultures and attitudes towards other gangs. The scene in which all the students enter room 203 and take seats into their separate corners of the room divided into their certain corners of the room shows the division between students in a real life. We see a long shot of the whole classroom showing its layout and the segregation between gangs. Then multiple mid-shots are shown of the gang itself and its individual members to decipher the multiple gangs, their attitudes towards school and their way of life. Even though the students start their school year with an attitude of ignorance towards other cultures they begin to learn the value of each individual and change their point of view and their gangs and cooperate with their cultures. People may argue that respect is something that has to be earned, it is not automatic. In the 1992 Los Angeles’s race riots, respect was something that was taken for granted, as it was essential for their society. In Freedom Writers, Ms Gruwell demanded respect immediately. Not surprisingly the students refused to give it to her and why should they of, they didn’t know anything about Ms Gruwell. Towards the end of the film we see that Ms Gruwell has gradually gained the respect she wanted from her class. We are shown this in a first hand basis as Andre, a gang member, calls Ms Gruwell ‘Mam’. She takes this as an offence and claims she is not anyone’s mother; Eva soon corrects her and states that it was a ‘sign of respect to you’. This scene is shown to us by a series of close up shots of Andre, Ms Gruwell and Eva. This is purposely done to capture the changing emotion in the characters face. The students of room 203 value Ms Gruwell not only as a teacher and a person and this is reflected in their attitude and behaviour. We all know what racism is and have most likely been subjected to it or witnessed it at one time in our lives. Racism is more prominent in schools and work places although random attacks of racist acts can also be seen in the streets or at public places where the offender and the victim may not even know each other. In the feature film Freedom Writers, every student at Long Beach either dishes out racist comments or receives them. When all of the ‘unteachable’ students get integrated into the same class we see this clash of cultures collide. A racist caricature is drawn of one of the African-American students and the rest of the students find it amusing. Ms Gruwell takes the picture and compares it to the Jews during the holocaust. Erin was greeted with dumb-founded looks only to find out the kids didn’t know what the holocaust was yet they acted out their lives in a similar racist manner. This scene is shown by using close ups of Ms Gruwell and the victim of the caricature, Jamal. We see Ms Gruwell looking horrified and Jamal’s expression looking embarrassed. We are also shown mid-shots of the whole class to show their expressions and they seem amused and proud of themselves. Towards the end of the movie the students do not lash out any forms of racism at one another and instead treat each other as good friends. At the end of Freedom Writers, the students have accepted and value each other as individual people not of their cultural back ground. Ms Gruwell gained the respect she earned from devoting her life to teach these children. During this essay I have explored the movie Freedom Writers and how factors like gangs, respect and racism can have such an impact on peoples lives. It can change peoples values on life and their attitudes and behaviours towards things and that is what we draw from the film.

The Difference Between Purines and Pyrimidines

The Difference Between Purines and Pyrimidines Purines and pyrimidines are two types of aromatic heterocyclic organic compounds. In other words, they are ring structures (aromatic) that contain nitrogen as well as carbon in the rings (heterocyclic). Both purines and pyrimidines are similar to the chemical structure of the organic molecule pyridine (C5H5N). Pyridine, in turn, is related to benzene (C6H6), except one of the carbon atoms is replaced by a nitrogen atom. Purines and pyrimidines are important molecules in organic chemistry and biochemistry because they are the basis for other molecules (e.g., caffeine, theobromine, theophylline, thiamine) and because they are key components of the nucleic acids dexoyribonucleic acid (DNA) and ribonucleic acid (RNA). Pyrimidines A pyrimidine is an organic ring consisting of six atoms: 4 carbon atoms and 2 nitrogen atoms. The nitrogen atoms are placed in the 1 and 3 positions around the ring. Atoms or groups attached to this ring distinguish pyrimidines, which include cytosine, thymine, uracil, thiamine (vitamin B1), uric acid, and barbituates. Pyrimidines function in DNA and RNA, cell signaling, energy storage (as phosphates),  enzyme regulation, and to make protein and starch. Purines A purine contains a pyrimidine ring fused with an imidazole ring (a five-member ring with two non-adjacent nitrogen atoms). This two-ringed structure has nine atoms forming the ring: 5 carbon atoms and 4 nitrogen atoms. Different purines are distinguished by the atoms or functional groups attached to the rings. Purines are the most widely occurring heterocyclic molecules that contain nitrogen. They are abundant in meat, fish, beans, peas, and grains. Examples of purines include caffeine, xanthine, hypoxanthine, uric acid, theobromine, and the nitrogenous bases adenine and guanine. Purines serve much the same function as pyrimidines in organisms. They are part of DNA and RNA, cell signaling, energy storage, and enzyme regulation. The molecules are used to make starch and proteins. Bonding Between Purines and Pyrimidines While purines and pyrimidines include molecules that are active on their own (as in drugs and vitamins), they also form hydrogen bonds between each other to link the two strands of the DNA double helix and to form complementary molecules between DNA and RNA. In DNA, the purine adenine bonds to the pyrimidine thymine and the purine guanine bonds to the pyrimidine cytosine. In RNA, adenine bonds to uracil and guanine still bonds with cytosine. Approximately equal amounts of purines and pyrimidines are required to form either DNA or RNA. Its worth noting there are exceptions to the classic Watson-Crick base pairs. In both DNA and RNA, other configurations occur, most often involving methylated pyrimidines. These are called wobble pairings. Comparing and Contrasting Purines and Pyrimidines The purines and pyrimidines both consist of heterocyclic rings. Together, the two sets of compounds make up the nitrogenous bases. Yet, there are distinct differences between the molecules. Obviously, because purines consist of two rings rather than one, they have a higher molecular weight. The ring structure also affects the melting points and solubility  of the purified compounds. The human body synthesizes (anabolism) and breaks down (catabolism) the molecules differently. The end product of purine catabolism is uric acid, while the end products of pyrimidine catabolism are ammonia and carbon dioxide. The body does not make the two molecules in the same location, either. Purines are synthesized primarily in the liver, while a variety of tissues make pyrimidines. Here is a summary of the essential facts about purines and pyrimidines: Purine Pyrimidine Structure Double ring (one is a pyrimidine) Single ring Chemical Formula C5H4N4 C4H4N2 Nitrogenous Bases Adenine, guanine Cytosine, uracil, thymine Uses DNA, RNA, vitamins, drugs (e.g., barbituates), energy storage, protein and starch synthesis, cell signaling, enzyme regulation DNA, RNA, drugs (e.g., stimulants), energy storage, protein and starch synthesis, enzyme regulation, cell signaling Melting Point 214 C (417 F) 20 to 22 C (68 to 72 F) Molar Mass 120.115 gmol1 80.088 g mol1 Solubility (Water) 500 g/L Miscible Biosynthesis Liver Various tissues Catabolism Product Uric acid Ammonia and carbon dioxide Sources Carey, Francis A. (2008). Organic Chemistry (6th ed.). Mc Graw Hill. ISBN 0072828374.Guyton, Arthur C. (2006). Textbook of Medical Physiology. Philadelphia, PA: Elsevier. p. 37. ISBN 978-0-7216-0240-0.Joule, John A.; Mills, Keith, eds. (2010). Heterocyclic Chemistry (5th ed.). Oxford: Wiley. ISBN 978-1-405-13300-5.Nelson, David L. and Michael M Cox (2008). Lehninger Principles of Biochemistry (5th ed.). W.H. Freeman and Company. p. 272. ISBN 071677108X.Soukup, Garrett A. (2003). Nucleic Acids: General Properties. eLS. American Cancer Society. doi:10.1038/npg.els.0001335 ISBN 9780470015902.

Final Assignment Example | Topics and Well Written Essays - 1000 words

Final - Assignment Example Looking at solar energy this is the sun’s energy that undergoes conversion by an n equipment to produce desired power to use as lamps and heat in the school, house, and industries. Other form of energy such as gas and coal comes from fossils, which will not remain available for long. To add on that, this fossils pollutes the air and hence causing harm to human being. Solar energy is clean and readily available furthermore its distinction is not measurable. This equipment produces light for human being to use. It can be streetlights, house light or even vehicle light. The different types of bulbs include those that save energy and those that use significant amount of energy. Basing to fluorescent ballasts, this bulbs tent to use small amount of energy compare to the other light emitting bulbs. Again this ballast supplements long life and to lamp and cost reasonably. This lamps are wired in parallel thus when one lamp blows off, the other one remains illuminated. This lamp is cheaper to install and use, also does not produce pollution in the environment. A green house is essential in that the plants use up carbon, which in turn produces oxygen that offers good air purification. In implementation, it is cheap since its easier to access it and more cheaper to organize the whole field. These plants are effective to human since they purify the air as well as using the sun making human kind to benefit from the rays. In the end, this leads to energy conservation. In both industrial and commercial buildings, fan is critical in that, it provides a source of cool breeze that gives comfort to workers. This fan is capable of blowing warm air that may be because of hot heat from the machine. This fan has ability to reduce up to 25% of heat produced in the industry. Wind is essential in the rotation of turbines making it give power for some big

Prostitution Essay Example | Topics and Well Written Essays - 750 words - 2

Prostitution - Essay Example The first main point for evaluation is the point of human rights. Perkins (1991) wrote about human rights in support of prostitution: â€Å"The decriminalisation of the prostitution legislation, therefore, would immediately free prostitutes from the shackles of unjust laws, but it would also be a positive step in removing a punitive threat to all women, especially those who aspire to freedom of sexual choice.† This is a main point because I strongly disagree with prostitution, and yet, Perkins presented an interesting concept that prostitution is a freedom of sexual choice. It is a good example of freedom of autonomy over one’s body that is hard to oppose. I definitely do not see prostitution as a sort of freedom, but prostitutes can claim their bodies as their own, therefore underscoring their human right to their job of choice. Post (2013) opposed Perkins when she said: â€Å"The practice of prostitution brands all women as something that can be bought and sold; and therefore, just like slaves, less than full humans who deserve the complete panoply of human rights.† I agree with her that prostitution is dehumanising, so it means it is not aligned with human rights. To be a prostitute is to be a slave to gender-based sexual desires that is not what humanity should be. I truly think that to have human rights and freedoms, prostitutes should have access to other alternative jobs. Leidholdt (1993) also disagreed with Perkins that prostitution is a human right or freedom: â€Å"[Prostitution] is about the absence of meaningful choices; about having alternative routes to survival cut off or being in a situation where you don’t have options to begin with† (p.136). I chose this as a main point because I agree that prostitution is against human rights because many prostitutes are known to say that they would leave prostitution

Rogue Waves Essay Example | Topics and Well Written Essays - 1000 words

Rogue Waves - Essay Example However, author critiques this factor as "rather unrealistic". Second factor is temporal-spatial focusing which is the result of applying dispersion to a wave group with chirped spatial distribution of frequencies. Author notes that this mechanism can work for the "forced" wavetrains only which can not develop spontaneously. Finally, third factor is nonlinear focusing which produces solitons and so-called breathers as model representations of rogue waves. About real mechanisms of the rogue waves forming in the open ocean, author concludes that 'nobody knows the answer to these questions yet.' My Comments: This paper shows that there are some fields for researches with no direct and clear answers. Real mechanism of the rogue waves forming in the open ocean is yet unknown. Existing mathematical models for explanation of these phenomena are refined but not realistic. Indeed, considered mechanisms for the wave energy focusing are operable only for narrow sets of cases or for unnatural conditions. Details of mathematical notations (especially in Appendix) were not clear for me. Article Summary: This is short but comprehensive introduction to the freak/rogue waves phenomenon. It contains well adjusted set of facts and ideas about rogue waves, namely: informal definition, brief history of observations with examples, discussion about causes of its origin, typical values of the break forces, sea conditions that may create (or accompany) freak waves, etc. There are no formulae at all. This article serves as global pattern for the rogue waves problem whereas numerous articles concentrate upon mathematical details and minor features of this phenomenon. My Comments: As for me, this is one of the best articles about rogue waves. Some facts are just amazing. For example, cases from the article show that freak waves greater than 25 meters in height are real and much more common than expected. Obviously, this phenomenon is far beyond so-called linear model. Than, actual causes and mechanisms of rogue waves are unknown (cf. previous article). Here, unpredictable freak waves are real miracles of the Nature, not mirages. It is important to distinguish freak waves and tsunamis. Then, article contains tremendous facts about the force of a breaking freak wave. It is about 100 MT/m2 for a 12-meter rogue wave which is much more than for wave in linear model. Article reading was easy and fascinating. Article is highly recommended for any scholar at the beginning stage of studying this phenomenon. Source: Proceedings of Rogue Waves 2004 Conference, Brest, France - October 2004. Off the Internet at: http://www.ifremer.fr/web-com/stw2004/rw/fullpapers/haver.pdf Article Name: Freak waves: a suggested definition and possible consequences for marine structures.