MEL and Analogues: Structures and Properties

MEL and Analogues: Structures and Properties CHAPTER 2 LITERATURE REVIEW 2.1 Melamine MEL is an organic compound which had been closely associated with milk adulterant scandal between the year 2007 and 2008. Having a chemical formula of C3H6N6, makes it a nitrogen rich compound, thus giving the false impression of real protein content (Y.-N. Wu, Zhao, Li, 2009). Manufacturing companies who bought raw milk for further production usually carry out protein tests by monitoring the nitrogen levels. MEL can be hydrolysed to ammelide, ammeline and CYA, the derivatives are many produce for the synthesis of formaldehyde resin in the manufacturing of plastics, kitchenware or laminates (Y. Wu Zhang, 2013). CYA commonly used as a bleaching component in swimming pools. MEL and CYA are soluble in water, however when the two combined they will form a MEL and CYA complex which is an insoluble crystal through cross linking hydrogen bonding network (Mukherjee Ren, 2010). 2.1.1 Structures and properties of MEL and analogues The triazine derivative, MEL has three reactive amine groups (-NH2) and one aromatic s-triazine ring or 1,3,5-triazine ring. Replacing the amine groups (-NH2) with hydroxyl group (-OH) through hydrolysis or metabolism by microorganism will form analogues as ammeline, ammelide and CYA (Kim, 2009). Figure 2.1 Structure of MEL, ammeline, ammelide and CYA (Kim, 2009) Physical properties of MEL and its analogues are shown in Table 2.1. MEL has an appearance in form of white powder with a melting point of 354oC. This shows that MEL is thermally stable and explains that it is often used as fire retardant. Furthermore, MEL is sparingly soluble in either acidic pH or polar organic solvent such as acetone or ethanol, due to like-dissolve-like interaction of polar compound MEL. On the contrary, MEL would be insoluble in non-polar solvents such as benzene or hexane (EFSA, 2010). Ammeline on the other hand is a white powder that decomposes prior to melting. It possesses weak acidic properties and is soluble in both mineral acid and alkaline solutions. Ammelide is also a form of white powder that is almost insoluble in water. It decomposes at temperatures range of 170oC to form carbon dioxide and ammonia. The crystal complex of MEL and CYA is very stable at only hydrolyses at either very low or high pH. Basically the complex crystal compound are insoluble at pH below 5.0, which is mostly occurred in the urinary tract (Tolleson, Diachenko, Heller, 2008). Table 2.1 Physical properties of MEL, ammeline, ammelide and CYA (Kim, 2009) 2.2 MEL and analogues toxicity The toxic effects of MEL ingestion are closely linked with high dosage and low dosage of MEL would not be as toxic that will cause any adverse effect to human health. However, having said that, non toxic does not necessarily mean that it is safe for consumption. On December 2008, the US FDA recommends a TDI for MEL was 0.63 mg kg-1 body weight per day for food and other food ingredients excluding infant milk formula (Venkatasami Sowa, 2010). This meant 100 kg person can be subjected to a tolerable amount of 60 mg MEL. Infant formula are given a closer monitoring because it is a primary source of nutrient and calorie for infants, plus kidney functions in infant are still premature. Therefore the FDA has set a limit of 1  µg mL-1 for MEL in infant formula (Venkatasami Sowa, 2010). Different countries apply different limit of the TDI, for instance EFSA recommended a TDI of 0.5 mg kg-1 of body weight per day. Whereas Health Canada revealed the risk assessment of MEL-contaminated milk and milk based product to be 0.35 mg kg-1 body weight per day (WHO, 2008). Over Southeast Asia, the Malaysian Ministry of Health has set the maximum levels of MEL in baby and adult food product to be 1.0 mg kg-1, 2.5 mg kg-1 respectively (Y. Wu Zhang, 2013). This incident cause the FDA, European community and other countries to introduce a standard limit for MEL in infant formula and in other milk products to be at 1 ppm and 2.5 ppm, respectively. WHO established the TDI for MEL at 0.2 mg kg-1 (Sun et al., 2010). 2.2.1 Toxicity in animals and humans The data available on the dangers and chronic human exposure to MEL are limited, therefore the information on MEL toxin are extrapolated from animal data. MEL and CYA are considered as low toxin due to their large median LD50. For MEL in rats, the LD50 ranges from 3.1 g kg ­-1 to 6.4 g kg-1 and from 3.2 g kg-1 up to 7.0 g kg-1 in mice. Whilst for CYA, the estimated LD50 are 7.7 g kg-1 in rats and 3.4 g kg-1 in mice (Skinner et al., 2010). The study on the toxicity of MEL and CYA focuses on the urinary system for both humans and animals. The experimental studies on the effects of MEL on kidney in humans are unavailable. Nonetheless, consistent observation was made during the experiment with animals on the effects of MEL is bladder stones. The same result was reported with a following exposure to CYA, and that is formation of some bladder stones. Inflammatory reaction was observed in the rats and mice urinary bladder after dietary exposure to MEL. This indicates as one of the main effects of the toxic of MEL (Bingham et al., 2001). In general death cause by MEL are relatively low in human but there is a high rate of stones formation. In the height of the MEL food scandal, there are many deaths of pets animals in USA, Canada and South Africa due to kidney failure. Later the Veterinary Information Network (VIN) found that the number of deaths due to MEL and CYA contaminated pet feed was in the range of 2000 to 7000 (Puschner and Reimschuessel, 2011). In 2008 there were high detection of MEL in infant formula and other milk product and surely enough this resulted in severe health effects amongst infant and young children. As much as 294,000 were diagnosed with urinary tract stones and at least 50,000 were hospitalised. Six children were confirmed dead cause of kidney failures (Dorne et al., 2013). After this incident strict rules and regulation was implemented, and lots of method was developed in order to get a rapid and sensitive detection of MEL. 2.3 Analysis of MEL It is important to have rapid, widely available, cost effective methods for detecting MEL in various samples. Few of the advance analytical methods for detection of MEL are High Performance Liquid Chromatography (HPLC), Liquid Chromatography with Mass spectroscopy (LC-MS), LC with tandem (LC-MS2) and Gas Chromatography with MS (GC-MS). Sample preparation required prior to instrumental analysis, this is because the sample in question are high in protein and carbohydrates content which would hinder MEL detection. Therefore effective extraction methods is necessary, by removing other constituents in the matrix would mean lower limit of detection (LODs) can be achieved. Due to the polarity MEL compound it is best to extract it using SPE with a polar cartridge. The most common SPE tubes used for the separation of MEL is Supelco Discovery DSC-SCX 500 mg/6 ml (Sigma-Aldrich, n.d.). Before the SPE methods are applied it is best to precipitate out the protein by adding acetonitrile which acts as a protein precipitant and then centrifuge (Mosch, Kiranoglu, Fromme, Và ¶lkel, 2010). 2.3.1 Gas Chromatography with Mass Spectroscopy (GC-MS) GC-MS is often used to detect MEL and its analogs for quantification and confirmation. It was reported that it is a sensitive, reliable instrumental analytical method for the simultaneous detection and quantification of MEL in animal feed. However, it requires a tedious sample preparation which renders the methodology impractical for analysing large samples (Venkatasami Sowa, 2010). 2.3.2 High Performance Liquid Chromatography (HPLC) HPLC is known as common method for quantitative determination of MEL. It can carry out simultaneous detection of MEL, ammeline, ammelide and CYA with LOD of 5 ppm. By current standards, this method of analysis does not show great sensitivity in detection of MEL. This is because UV of MEL exhibits absorption bands below 250 nm which meant that HPLC method will not be able to confirm the target analyte (Sun et al., 2010). Quantification error can occur if insufficient attention is given to chromatographic conditions or if sample preparation is not optimised. To increase sensitivity investigators used DAD system of detection, this gives improvement in term of better LOD of 0.1 ppm using HPLC-DAD (Sun et al., 2010). It is difficult to retain MEL on a reverse phase column due to it high polarity, so to compensate for this problem hydrophilic interaction chromatography technique is used (Han et al., 2011). Figure 2.3.2 Retention time of melamine standards using HILIC-UV (Zheng, Yu, Li, Dai, 2012) 2.3.3 Liquid Chromatography with Mass Spectroscopy (LC-MS) and tandem Mass spectroscopy (LC-MS2) MS techniques are widely used for the determination of contaminants of MEL, because it shows molecular specificity and high sensitivity of detection. This means a MEL AND CYA having fairly low LOD 30 ppb and LOQ 40 ppb in serum sample. Mostly the method based on LC-MS2 with HILIC and ESI is positive ion mode. Positive ion mode is chosen because of the presence of nitrogen in the compound. The past researcher used two selected reaction monitoring (SRM) transitions of m/z 127 till 85 and 127 till 68 were monitored, figure 2.3.3. By applying these ion transitions for SRM allows quantitative and qualitative analysis of MEL residues at an LOD of 3.2 ppb (Sun et al., 2010). Figure 2.3.3 The positive ion electrospray full scan mass spectrum (bottom) and product ion spectra (top) of melamine, acquired by infusion of 0.5 g mL -1 standard solution (Sancho, Ibà ¡Ãƒ ±ez, Grimalt, Pozo, Hernà ¡ndez, 2005). 2.4 Optimization of buffer pH MEL is a weak alkaline compound that can hydrolyze in strong acid or alkali solutions. MEL extraction can be carried out in neutral, acidic and alkali conditions, but acidic pH lower than 3 and neutral extraction conditions are most common for food. Neutral extraction can be carried out using acetonitrile-water or methanol-water. Factors of affecting retention of melamine were explored, including buffer concentration, pH, and percentage of organic solvent in the mobile phase. The optimal UV detection wavelength was selected. Satisfactory retention of melamine, good peak shape, and high sensitivity were obtained under the chosen conditions. Tables 2.4 Effects of pH on melamine retention time

To His Coy Mistress Essay: An Act of Persuasion -- His Coy Mistress Es

   To His Coy Mistress: An Act of Persuasion  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚      In the poem by Andrew Marvell, he tries to persuade a lady of his love, that she should do as he wishes,   and give herself up for him.   In order to do so, he expresses his arguments in the poem being discussed.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   In the second line he starts off trying to persuade her,   by telling her that she really does want to give herself up to him,   but is too shy.   He reassures her, and tells her that this does not matter, and there is nothing wrong with it, however she must look beneath her coyness.   This seems to be his main argument, along with the concept of time that is discussed on a very broad basis.   The reader is also informed of the title of the poem, and this makes it clear to the reader, and indeed his mistress, that this is all that stands between her and his love    â€Å"This coyness, Lady,   were no crime.†    the poet tries to persuade her by continuously reminding her about the problem of time.   He does this by mentioning the Indian Ganges,   and the Flood.   The Indian Ganges supposedly mark the end of time,   whilst the Flood marks the end of life as well,   but in the biblical sense.    â€Å"Thou by Indian Ganges’ side†    â€Å"Love you ten years before the Flood†    This idea of time running out is also emphasised further in the middle of the poem,   as well as right at the end.   At first he mentions that she shall not live for ever,   and the day will come where she will die,   and then they can no longer enjoy each others love.    â€Å"Time’s winged chariot hur... ...x lines of Andrew Marvell’s poem,   he brings across a certain image.   The imagine of time hurrying on,   and there being nothing he can change about it.   He tries to create an image of the two of them finding there way together,   and making the best of things.   He seems to want to suggest to her,   in an open and honest way,   that he cannot promise that their future will always be rosy,   but it should be a future and a destiny they should share.    â€Å"And tear our pleasures with rough strife†    The closing six lines paint a very harmonic picture in the readers eye,   and with it a peaceful image of two lovers going through life together,   and cherishing every minute,   until they day that they die.    â€Å"Thus,   though we cannot make our sun Stand still,   yet we will make him run.†

Discussion Board, Jamie & Carolyn

In the world today, there are a lot of unfortunate people who are suffering due to the conditions that they find themselves in as a result of natural disasters or other unrelated issues. Every human being has the right to have a good life through education, healthy life and income stability. However, this can only be achieved by the existence of humanitarian organizations such as the United Way as some of the governments in these areas are not capable of providing the services. These humanitarian organizations are not profit making and this means that they survive on grants from other profit making organizations. As Smith et al. (2000, pg 285) says, it is necessary for nonprofit organizations to be honest and transparent in their finances. This is the only way that they will win trust of their donors who provide with finances which help them to achieve their mission. Transparency should not only be on their finances but should also be on the way they govern their organization and the people they hire to provide the services. (Smith et al, pg. 311, 330)Response to Carolyn PostingIt is the dream of every human being to have a better life. However, this can only be achieved if one has a constant income which can only provided by a good job. To get a good job, one needs to be educated so as to acquire the skills needed. However, as Smith et al, (2000, pg 309) says, education and skills are not the only things that are needed for a person to get that good job, there is a need to get the knowledge that will help you to prove to the employer that indeed you are the one who should get that job.These are the services that are offered by Goodwill Industries International Inc. Such services require one or the provider to be honest. This virtue can only be given by an organization that does not look forward to some gains from the client. Nonprofit organizations such as Goodwill Industries International Inc. are therefore known to train individuals with utmost good faith. T his is known to help them conduct humanitarian and other activities in any type of organization they may be in. (Smith et al, pg 288) ReferencesSmith, B. et al. (2000). The Complete Guide to Nonprofit Management. New York: John Wiley & Sons, Inc.

If with conditional clause

If with conditional clause If with conditional clause If with conditional clause By Guest Author This is a guest post by Yvonne Canchola. If you want to write for Daily Writing Tips check the guidelines here. The tiny word â€Å"if† sets many, many language traps for the hasty. Consider this note: â€Å"If you happen to be in the area, we will be at Meehan’s Ale House. So stop on by.† Nice to be invited and welcome, isn’t it? But wait! I think this must be a magical reunion: telepathically- or by owl post, my friends will know that, by happenstance, I am indeed close by, and instantly they convene in the place we agreed upon. So really I have no need to RSVP, because somehow they will know, and the gathering will already be in place when I find time to make my appearance. Of course, my friends’ trip to the pub is not conditional upon my whereabouts, but that is what the use of if suggests. The intended meaning is that my friends want to let me know that they will be at the pub whether my business takes me their way or not. They will be at the ale house. If I happen to be in the area, I can join them. The problem with this type of sentence is not grammatical; it’s semantic. The part of the thought process that is conditioned by the if-clause is missing. The error, actually an omission, can be fixed quite easily: â€Å"If you happen to be in the area, remember that we will be at Meehan’s Ale House. So stop on by.† Other instances of this kind of error: â€Å"If you are new to my blog, I post a poll every month†¦.† should read, â€Å"If you are new to my blog, I have to catch you up: I post a poll every month.† â€Å"If you have not already seen the new Tim Burton movie, it really is something!† should read, â€Å"If you have not already seen the new Tim Burton movie, let me tell you: it is really something.† However, â€Å"if† does not strike me as the most precise word choice here. I would suggest, â€Å"Assuming that you have not already seen†¦.† â€Å"If you have ever seen xyz movie, that’s what our vacation was like.† should read, â€Å"If you have ever seen xyz movie, you can imagine our vacation† â€Å"If youre interested in xyz product, half of the payment is due by April 30th.† I doubt that the price is conditional on your interest. Despite my personal lack of interest, for the rest of the people who have decided or will decide to purchase it, half of the payment is probably still due by April 30. Thus, it should read, â€Å"If youre interested in xyz product, you need to know that half of the payment is due by April 30th.† Here again I would choose â€Å"in case† or â€Å"assuming/supposing that† instead of â€Å"if.† While the above sentences are perfectly understandable to colloquial speakers of the English language, non-native speakers may stumble. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Grammar category, check our popular posts, or choose a related post below:50 Handy Expressions About HandsOn Behalf Of vs. In Behalf OfThe Two Sounds of G

s Mistakes

Saul’s Failures Although Saul was the chosen king, he did have his share of significant failures. In 1st Samuel 13:8-14 it describes how Saul impatiently intruded the office of a priest, yielding to the pressure of the moment. Samuel reprimands Saul saying, â€Å"Thou has done foolishly, thou has not kept the commandment of the Lord thy God, which occurs in 8:13. Saul exhibited extremism in his actions. His pendulum swung from complete inactivity and failure to lead an army against the attacking Philistines, to uttering a rash vow that insisted no one eat anything until all the Philistine army was vanquished. This not only brought Jonathon into danger, but caused the people to break the law and eat the meat with the blood. Saul was even deceitful with God. He claimed that he completely obeyed Gods instructions regarding the Amalekites when in reality he only partially obeyed the Lord. He spent his time chasing David around the wilderness, and finally consulted with a which in Endor. Saul flipped from inactivity to hyperactivity, disqualifying himself for leadership.... 's Mistakes Free Essays on Saul\'s Mistakes Saul’s Failures Although Saul was the chosen king, he did have his share of significant failures. In 1st Samuel 13:8-14 it describes how Saul impatiently intruded the office of a priest, yielding to the pressure of the moment. Samuel reprimands Saul saying, â€Å"Thou has done foolishly, thou has not kept the commandment of the Lord thy God, which occurs in 8:13. Saul exhibited extremism in his actions. His pendulum swung from complete inactivity and failure to lead an army against the attacking Philistines, to uttering a rash vow that insisted no one eat anything until all the Philistine army was vanquished. This not only brought Jonathon into danger, but caused the people to break the law and eat the meat with the blood. Saul was even deceitful with God. He claimed that he completely obeyed Gods instructions regarding the Amalekites when in reality he only partially obeyed the Lord. He spent his time chasing David around the wilderness, and finally consulted with a which in Endor. Saul flipped from inactivity to hyperactivity, disqualifying himself for leadership....

Politics of the Developing World Essay Example | Topics and Well Written Essays - 1250 words

Politics of the Developing World - Essay Example On the other hand, the south comprises of Africa, Asia, and Latin America. Political Economy This is a term used to describe the relationship between the state, the legal system, and the economy. In general, terms it captures the interplay between the three facets in a way that determines the stability of countries and the economic structures. Development refers to the growth of a country in terms of matters of economy, governance, and human development. The term embraces such areas as the growth of GDP, economic growth in relation to the improvement of infrastructure, healthcare, education systems, and other indicators of growth. New International Economic Order The term describes a combination of proposals created by developing countries in the 1970s with the objective of improving their economies. The proposals included the improvement of trade terms through favorable tariffs and enhancing development assistance. Walt Rostow (1916-2003) He was a renowned American economist and an acclaimed political thinker. Rostow was a staunch defender of capitalism and policies of a free enterprise in the twentieth century. Rostow played a significant role in determining US foreign policies particularly with regard to Asia. Raul Prebisch (1901-1986) Prebisch was a renowned economist from Argentina remembered for contributing to the development of structuralist economics. He developed a trade-focused approach on matters of development and recommended preferential treatment for some countries in trading matters. Hans Singer (1910-2006) Singer was a German development economist. He believed that terms of trade generally do not play to the advantage of primary producers. He advocated for the increment of foreign aid to poor countries. Hegemonic Stability Theory The theory was developed for understanding international relations. The leadership of a hegemon in whatever form eventually results in the deployment of its influence on economic systems. The theory is largely attribut ed to Robert Keohane although various theorists who gave it varying interpretations developed it. Joseph Stiglitz (1943-Present) Stiglitz is an American economist well known for his strong support of globalization and the creation of free market economies. Much of his contribution in economics are in the areas of income distribution, international trade, corporate governance, and other areas that relate to modern economies. Section B 1). Different Interpretations of Poverty The United Nations approach to poverty was largely focused on the aspects of unemployment, equality, and poverty. On the other hand, the Bretton woods institutions focussed largely on the aspect of economic development as the key driver of development or the elimination of poverty. The United Nations was cognizant of the fact that economic growth does not necessarily translate into development. The difference between the two systems is mainly focused on the human factor at the core of the developmental initiative s. The IMF and World Bank kind of development was largely hinged on the development of free-market economies, which would spur economic growth and eventually lead to the elimination of poverty. 3). Realism, Institutionalism, and Structuralism The realist view, as understood within the framework of the International Political Economy (IPE) was based on policies that supported the use of tariffs to shield weak and infant economies.

Popular Culture Race and Ethnicity in the Movie King Kong Review

Popular Culture Race and Ethnicity in the King Kong - Movie Review Example Accordingly, the representation of blacks and minorities, or indigenous populations in film, has become an issue of social concern. The objection which several critics expressed towards King Kong (2005) and their denouncement of it as a racist film needs to be understood within the context of the larger social issues at stake and should not be dismissed as exaggerated reactions to innocent entertainment, as some have done. Indeed, King Kong is founded upon racial stereotypes and cements racial prejudices in its portrayal of indigenous populations as savages, its suggestion that blacks are wild beasts, such as is King Kong, who can only be tamed by the civilised Caucasian. Critical reactions to King Kong (2005) have tended towards its denouncement as a racist film, on the one hand, to its defence as innocent entertainment, on the other. Espousing the former view, McCarthy (2006) maintains that the storyline and plot revolve around three of the oldest and most persistent of the known anti-black stereotypes. These are that all non-Caucasians are savages and that members of the black race are hardly distinguishable from wild beasts (McCarthy, 2006). In this film, the non-Caucasians are represented in the hardly human, unmistakably savage and completely unwashed figure of the Skull island natives and blacks in the form of the gigantic and uncontrollable savage figure of the ape. The third stereotype upon which this film is founded and which its storyline propagates and legitimizes is that of the civilized Caucasians who, by the very nature of their appearance and the culture and civility which they symbolize, are able to tame, control and potentially even civilize the savage and the wild. King Kong (2005) promotes these stereotypes and should, accordingly, be classified as a racist film. For multicultural societies which are struggling to create a culture of racial tolerance and acceptance to replace the culture of racism, films such as this can have a potentially detrimental effect. Pon (2000) highlights this potential consequence by arguing that racist messages legitimize an audience's possibly racist sentiments and justifies their perception of minority races and groups as inferior. When these messages are conveyed in a multicultural society, they immediately conflict with multiculturalism's message and, accordingly, can contribute to racial tensions (Pon, 2000). In direct reference to Canadian society, popularly regarded as a successful experiment in multiculturalism, the message conveyed by King Kong (2005) does not simply conflict with official messages regarding racial tolerance and understanding but it touches upon the underlying racial tensions which exist beyond the surface. Studies have indicated that increasing numbers of racial minority groups and indigenous populations feel marginalized and discriminated against. The number of blacks and natives feeling out of place in society is on the rise. In 2002, 35% of blacks and 20% of natives in Canada reported unfair discriminatory treatment 'sometimes' or 'often' (Statcan, 2002). Therefore, films which wrongfully portray the true nature of blacks and native/indigenous populations, have the potential to enhance the mentioned feelings of marginalization and to deepen the racism which many Canadian minority groups feel they are subjected to. The fact that King Kong