Tuesday, January 28, 2020

Standardized Ion Chromatograpy (IC) for Salivary Analysis

Standardized Ion Chromatograpy (IC) for Salivary Analysis According to Darvell et. al. (2004), the research is about analysis of human saliva by using ion chromatography(IC). The aim of this research is to construct out a standardized IC protocol for future salivary analysis. The samples has go through several procedures such as centrifugation to remove particulates, filtration on supernatant, and the residual droplet was removed by a paper tissue without touching it to the CFD (centrifugal filter device). This is because want to minimize the risk of back–contamination of the device. About the pretreatment, the temperature for centrifugation is set at 4Â °C which inhibit the pathogen spreading and lower the bacterial activity. The steps of pretreatment temperature, duplicate runs of the samples and recovery of known addition of standard solution are to make sure that the result obtained is reproducible and no significant different. However, the resolution has shown decrease and this may cause by the protein retained in the exchange site of column resin or the surface of suppressor. It is suggested that application of membrane ultrafiltration can minimize contamination of IC system. Besides, there are few things have to take in consideration which are pretreatment and sample dilution. If the sample pH is higher than 2-3, in pretreatment part have to avoid introducing the ionic contaminant or subtracting any ion that needed if cellulose used in material for membrane ultrafiltration. Sample dilution can make the resolution between peaks greater especially when fluid with smaller volume are available sufficient for injection. Xie et al. (2011) have reported the studies on levels of adenosine phosphate in blood which are analyzed by using ion chromatography. In this research, gradient mode of elution is used, because it well-known as can carry out fast result and provide sharp peak due to gradient compression effects. The procedure are firstly sample dilution, homogenization, centrifugation, membrane filtration and finally injection into the IC system. The addition of acetonitrile in homogenization part is to extract out the protein as precipitation. Adenosine phosphate likely retained in column and cause contamination since they are very polar molecule however this research has proven that by using this method it will not retained on the column and it can applicable to the analysis of true blood samples. Hou Cramer (2011) has evaluated on selectivity in multimodal anion exchange system priority on prediction of protein retention time and investigation of effect caused by mobile phase modifier. About selectivity, as we know protein are more strongly retain tendency with resin. The multimodal effect which the arrangement pattern has given an electrostatic attraction that manage the binding behaviors with obeying Langmuir isotherm. In this research, two anion resin was used which are Capto Adhere(ADH) and Q Sepharose FF. Result shown there was more retention on ADH because additional interactions existed. In ADH ligand, the additional interaction may composed hydrophobic properties contributed by aromatic ring and hydrogen bonding contributed by hydroxyl group. Suggested that the size of ion-exchanger should be smaller to optimize the performance and using monolithic porous column in order to improve the morphology of the resins. According to the Tyrrell ed. al. (2009), rapid IC have several advantages such as reduce the analysis time, cost and improve the productivity. The rapid IC can be transfer from the conventional method by modifying some parameter. The rapid IC using the similar stationary phases with the conventional chromatographic but the column geometry used in rapid IC was modified. Besides that, the volume used and the flow rate of sample were reduce by a factor of 12 to speed up the chromatographic process and the resolution is not affected for the smaller particle-packed columns with shorter length. In generally, gradient elution are consider more beneficial in fast separations and multi-component sample analysis. In optimize conditions, the separation speed is assume constant in this study. Meanwhile, the other parameter such as the column length was decreased by a factor of 10 and the smaller particles were reduced by a factor of 15. Reductions by factor in the parameters was reduce the resol ution, but the reduction in resolution still in the acceptable ranges, so the process still can be accepted. According to Chen Leong (2009), ÃŽ ±-fetoprotein (AFP) is a potential candidate in biopharmaceutical field, especially in the treatment of autoimmune indications. Recombinant AFP can indicate rheumatoid arthritis recently. However, due to the complexity of its structure as it contains 32 cysteines, which refolding and form 16 disulfide bonds by oxidation; the refolding process will be very hard to occur because the protein with highly disulphide-bonding is immobile on a stationary phase of chromatography. The objective of this study was to improve the refolding yield of the recombinant human AFP (rhAFP) using anion-exchange chromatography. Refolding process by batch dilution was studied as a control. Instead of ion-exchange column, a PD-10 desalting column was used to remove the DTT from protein mixture. The mixture was then eluted out the desalting column and refolding buffer was added. There were two types of anion-exchange column to carry out on-column refolding, which were Q-FF columns and DEAR-FF columns. Same procedures were performed on this refolding process as batch dilution, the protein was incubated in the column with refolding buffer for 0-24 hours, but with an addition of stripping buffer after refolding cycle. Next off-column refolding was carried out using a 1ml Q-FF column. Unlike on-column refolding, the protein was not incubated in column but treated with refolding buffer with or without 0.5M L-arginine after elution process. For batch dilution, as a result, the refolding yield is at maximum level which was around 55% at less than 0.5mg/ml of rhAFP, but at the allowable greatest concentration of protein refolding which is 0.45mg/ml, the yield of refolding obtained is 14% only. This is because high concentration of protein would lead to high aggregation and hence, low refolding process. 0.45mg/ml was the highest protein refolding concentration in this section because of solubility and viscosity limitation in preparation step of higher concentr ation of protein sample. On the other hand, refolding process in DEAE-FF column had higher recovery yield of rhAFP compared to that in Q-FF column which were 19% and 15% respectively when the amount of rhAFP load was 1mg. Q-FF is a strong anion-exchanger compared to DEAE-FF, this caused the strong interaction between protein samples with matrix and limited the disulfide shuffling to refold. In contrast, the interaction in DEAE-FF is relatively weaker, so the disulfide shuffling had higher efficiency and increased refolding process occurrence. The stripping buffer was added after refolding cycle to elute more refolded rhAFP, as the protein was mostly bound on column during refolding and elution process. Similar to result of batch dilution, increased amount of protein load brought increased aggregation and lower refolding process. Furthermore, aggregation of protein at the top section of the column can prevent the protein to move through the column, so another test was done with addit ion of NaCl to refolding process conducted in DEAE-FF column and it showed higher refolding yield. Investigation of off-column refolding was done without incubation of protein in Q-FF column with refolding buffer. Without addition of L-arginine, the refolding yield of 1mg of rhAFP load was higher than on-column refolding, and the yield could be increased to 42% after addition of L-arginine. The possible reason is due to interference of L-arginine toward the adsorption of rhAFP on the matrix. Hence it is impossible to add L-arginine if on-column refolding was desired to be performed. Actually, instead of Q-FF column, the off-column refolding can be conducted on DEAE-FF column with addition of L-arginine and NaCl, the outcome should be interesting to investigate. In a nutshell, off-column refolding yielded the most among the methods, which was 13-fold increase from batch dilution.

Monday, January 20, 2020

Why American Troops Are Being Sent Overseas :: essays research papers

American troops are being sent overseas to maintain peace in a nation involved in a civil war. Whether the peace troops should or should not be sent overseas, they are being sent overseas. I do not believe that it is the responsibility of American troops to make peace in a country that is at Civil war. A civil war is a war fought within a nation between that nations people. By sending peace troops to East Timor the United States is now becoming involved in this nations war. This could cause the United States to go to war. The arrival of multinational troops could bring more violence, destruction, and chaos to East Timor. On the other hand it could also bring protection to the many people who have fled the violence from the Indonesian Militia. Force should not have to be used to make or keep peace in any country; therefore it is not necessary for American troops to have to risk there lives trying to make peace in a country that won’t make peace until they get what they want, INDEPENDENCE. Sending troops into Dili, East Timor may help persuade the people to make peace, but it is not necessary to send all of those troops. Just a few mediators would be sufficient to help make peace. If the nations at battle would just talk they might be able to negotiate a peace treaty and there would be cooperation without more violence. American troops would not be exposed to the violence either.The United States is a country known for helping other countries in there time of need, and the United States always plays a big role in every country, whatever the situation may be. East Timor is fighting for there independence. The United States should not send more troops to help the Dili militia fight, but send trained people who know how to persuade people to make peace. Then the United States would be setting a good example by not using violence, and would still be protecting the people. The role of the United States is very important, and the United States has quite an image to keep up. Sometimes the United States does not know what the right decision is, and until they try one of there choices they will not know what the right or wrong decision is. It is not the United States responsibility to make peace in a country at civil war.

Saturday, January 11, 2020

An Analysis of Writing Techniques in the Achievement of Desire Essay

This essay is elegantly written with well-chosen words. Besides that, Richard Rodriguez’s adept skills in depicting the author’s complicated yet conflicting mental activities through various literary devices is also the shinning point of this piece of work. In the essay, the author mainly used several techniques such as flashbacks, comparisons and contrasts, definition, quotation, and satire to enhance the readability and entertainment of its content, which cater to most readers’ tastes and could lead them to further and in-depth thinking and reflection. Before analyzing the Rodriguez’s skills to shape and present his idea, a briefing on the essay is necessary. Rodriguez, the author, devoted most of his time to gaining knowledge. He saw schooling as the best way to get rid of his embarrassed status as an immigrant Mexican and to escape from being a poor educated person as his parents. However, after reading hundreds and thousands of classics, he found himself becoming a â€Å"scholarship boy†, otherwise pedant or book worm, overweighed with knowledge but do not have his own views on things. In other word, the whole learning process of him is mimicking and memorizing other’s words. He did not realize this until he wrote a dissertation on Renaissance Literature. He became bored of ceaseless learning and grew nostalgic and missed the family intimacy and consolations. But what irony is that in his efforts to return his family life, he found that it was education that enabled him aware of his status quo and gave him another chance to cherish the forthcoming life. Now, after gaining a rough idea of the essay, we could turn to his first writing technique-flashback. Most stories began with such a written pattern, which could leave the readers in suspense and give them a lingering aftertaste. This is also true of Rodriguez’s work. In the opening of the essay, the author appeared as the guest speaker to give a lecture on the mystery of the sounds of words to the ghetto students. No one was really interested in his speech except a girl whose eagerness to learn and ways of taking note reminded the author of his school days. In order to propel the readers to move on, he uses such a sentence â€Å"It is myself (as a boy) I see as she faces me now (a man in my thirties)†. How could an adult see his youth in a girl’s eyes? A question like that will occur to most readers’ mind, and as a result they would read on with the intention to unravel it. This sentence also plays play the role of linking the preceding and the following passage, because in the second paragraph the author began with words like â€Å"the boy†. The following paragraph all dwelled on in a sequential narration matter. Apart from leading the reader to run along the plots, the main intention Rodriguez employs flashback is to introduce the main question, which is also the clue running through the whole essay, â€Å"How did I manage my success? †. By putting forward the question, the whole work has a pivot on which the reader could gain a better understanding of Rodriguez’s strange behaviors and complicated emotions in the rest content. The sharp and stark comparisons and contrasts between classroom and home, family life and school life, teachers and parents are also prevailing in Rodriguez’s writing. In Rodriguez’s eyes, home is a place one could feel the intense pleasure of intimacy and consolations while classroom is a place relatively reclusive and lonely, but the latter is more favorable when one is ready to embark on a road to knowledge. School life is dull and attentive while family life (concerning the author’s situation, the working class may be more pertinent) is an adult life full of trivial and petty things related to mundane life, such as Rodriguez’s description of his mother’s ironing and father’s habitual self-talks. Teachers, as Rodriguez sees it, they are the idols who could guide him in the process of searching for more knowledge. We can see this in his narration that even as a fourth grade students, he asked his teacher for booklists and librarians even reserve books for him. Parents, however, are poor educated who speak English with Mexican accent, making Rodriguez rather shameful in the grammar school graduation ceremony when the nun condescended to speak to them. These three comparisons and contrasts could be concluded as the conflicts between study and family. The author, with the eagerness to read more and the ambition to become elite, he chose the former. All these may render a strong sense of sympathy in the readers. They may be sorry and even curse the education which brings the author into such a tragic situation. Some readers, who have an intense interest in unrelenting pursuit of knowledge, might awaken to the reality that they are also leading a tragic life just like the author. Consequently, the illuminations people obtained from this essay may even change their way of life. Definition could also be spotted in this essay. The key term, scholarship boy coined by the author, has multiple levels of meanings. Definitions like â€Å"the scholarship boy must move between environments, his home and the classroom, which are at cultural extremes, opposed†, â€Å". . . The scholarship boy does not straddle, cannot reconcile, the two great opposing cultures of his life. †, â€Å"the scholarship boy makes only too apparent his profound lack of self-confidence. †, â€Å"The scholarship boy is a very bad student. He is the great mimic; a collector of thoughts, not a thinker. † and so on so forth. Any reader, who follows closely with the author’s flow of thoughts, could readily identify the scholarship boy he referred in distain and shame is himself. We could also draw such a conclusion from the last paragraph â€Å"I was a scholarship boy at the time†¦Ã¢â‚¬  So why does Rodriguez define it so frequently with different interpretations? What’s his purpose? In my view, Rodriguez in doing so is just want to highlight his regrets of distancing himself from family life and his shame of being a machine learning by mimicking and memorizing without originality. Like a person who committed some bad deeds, he would keep bubbling and muttering to show his regrets and sorrows. This would also give a sharp impression on the readers, making them reflect on the purpose of education and their own ways of learning. Quotations are scattered in this essay, most of them are from The Use of Literary Written by Richard Hoggart. For instance, in order to explain a scholarship boy’s nostalgic feeling at the end of his education he cited a paragraph from Richard Hoggart’ book, â€Å"The nostalgia is the stronger and the more ambiguous because he is really â€Å"in quest of his own absconded self yet scared to find it. He both wants to go back and yet thinks he has gone beyond his class, feels himself weighted with knowledge of his own and their situation, which hereafter forbids him the simpler pleasures of his father and mother. . . .† The contradicting moods are vividly presented in these words, which also makes the readers easier to grasp Rodriguez’s painful and conflicting emotions. He wants to go back to the family life and enjoys the intimacy but his desire for knowledge prevented him from doing that, which resembles a girl who is longing for a piece of candy but her decayed tooth deprives this enjoyment. So the author must be very helpless and painful during this process. Satire is also another main technique the author used to better present his idea. The repeat definition of scholarship boy is a satire, people’s constant inquiry of the secret of his success and his unexpected answer (I couldn’t forget that schooling was changing me and separating me from the life I enjoyed before becoming a student. ). The biggest satire of this work is that the author found that the education made him distant himself from his parents while it again offered him chance to care for them. What an irony it is! These ironies add an entertaining yet painful effect to the essay and the readers, driving them to think deep. To sum up, all these writing technique do bring the readers forward and hold their attention, but the unique experience of the author is the trump card of this essay’s success.