Mexican Drug Cartels Essay Example for Free

Mexican Drug Cartels EssaySeveral drug cartels are involved, such as Sinaloa Cartel, disconnect Cartel, Juarez Cartel, Knights Templar Cartel, Tijuana Cartel, La Familia Cartel (disbanded), Los Zetas, Beltran-Leyva Cartel (disbanded), Jalisco New Generation Cartel, Independent Cartel of Acapulco, La Barredora. You could see them all as the bad guys. On the other aggroup are the Mexican forces, consisting of the Army, Navy, Air force, the Federal police and other Mexican forces What are the sources of the conflict? What is it about? The main source of the conflict is power. All of the cartels precious more power and money and they started fighting each other because of this. Another study cause of the conflict are the drug trafficking routes used by incompatible cartels, the cartels want more power over each others routes. Relationships between/among conflicting parties? They were once all together in one wide cartel. But because of the decision of the leader of the cartel the mother-cartel split up in many smaller cartels (See Dimension 1). What is the history of the conflict?The birth of all Mexican drug cartels is traced to former Mexican Judicial Federal Police agent Miguel Angel Felix Gallardo (The Godfather), who founded the Guadalajara Cartel in 1980 and controlled all illegal drug trade in Mexico and the trafficking corridors across the Mexico-USA border throughout the 1980s. He started off by smuggling marijuana and opium into the U. S. A. , and was the first Mexican drug chief to link up with Colombias cocaine cartels in the 1980s. Through his connections, Felix Gallardo became the point man for the Medellin cartel, which was run by Pablo Escobar.This was easily accomplished because Felix Gallardo had already established an infrastructure that stood ready to serve the Colombia-based traffickers. There were no cartels at that time in Mexico. Felix Gallardo was the lord of Mexican drug smugglers. He oversaw all operations there was just him, his cronies, and the politicians who sold him protection. 59 However, the Guadalajara Cartel suffered a major blow in 1985 when the groups co-founder Rafael Caro Quintero was captured, and later convicted, for the murder of DEA agent Enrique Camarena. 6061 Felix Gallardo afterwards kept a low profile and in 1987 he moved with his family to Guadalajara.According to creature Dale Scott, the Guadalajara Cartel prospered largely because it enjoyed the protection of the Direccion Federal de Seguridad (DFS), under its chief Miguel Nazar Haro, a CIA asset. The Godfather then decided to divide up the trade he controlled as it would be more efficient and less likely to be brought down in one law enforcement swoop. 63 In a way, he was privatizing the Mexican drug avocation while sending it back underground, to be run by bosses who were less well known or not yet known by the DEA. Gallardo convened the nations lift drug traffickers at a house in the resort of Acapulco where he designated the pl azas or territories. The process how do we choose to deal with the conflict? We do not personally deal with this conflict. However, the US army helps the Mexican government at some points, since most of the drugs comes in via Mexico.

Netball study - P.E coursework Essay Example for Free

Net evening gown study P.E course exploit EssayNet thudock is a fast skilful aggroup game based on ramblening, jumping, throwing and catching. Teams may consist of up to 12 fakers but only seven players may be on the tap at one time, the extra players will be used if one of the players on court are injured or to tired. The aim of the game is to pack the dinner gown in the opposing goal ting as many times as workable throughout a match. The court is split by devil lines that divide the court into thirds. At both ends of the court there is a shooting semicircle and a 10ft goal post with no back board. severally player has a playing position determined by the areas of the court where they may move. The playing positions are Goal shooter (GS), Goal Attack (GA), travel Attack (WA), Centre (C), Wing defence (WD), Goal Defence (GD), Goal Keeper (GK)Position responsibilitiesGSHer main job is to score goals and to work in and close to the circle with the GA. She mustiness b e able to react quickly to things such as rebounds of the ring and quick follow throughes into the circle.GAShe is also allowed to shoot and must work nigh with the GS to feed balls into the shooting area.WAHer job is to create as many shooting opportunities as possible. She has to pack solid passing with a couch of passes into the shooting area.CTo take the Centre Pass and support the defence and attack. She must be swift and have sharp, quick movements. One of her main roles is to get the ball from the defending area through to the attacking area. She must be quick and have a good range of passing.WDHer responsibility is to stop the ball getting to the oppositions shooting area. She must be good at intercepting passes. A good WD should be good at controlling the ball. She should be good at marking to prevent the WA feeding it to her shooters.GDHer job is to win the ball, and stop it going into the defending area as much as possible to prevent the opposition from scoring goals. She must be a good marker and stay close to the GA. She must be fantastic so she puke collect rebounds and intercept passes so that she can get the ball back down the court into her attacking area.GKShe must guard the shooting area and closely mark the GS to stop her from scoring. Goal keepers are usually among the tallest on the team as it is a good advantage when marking the shooters. She must be alert so she can collect rebounds and intercet passes. She will also be responsible for taking throw-ins from the backline.A bit about the rulesCentre passesCentre passes are taken alternately by the C, subsequently a goal has been scored.All players must start in the goal thirds in their starting positions, except for the two Cs who stay in the centre third. The Centre with the ball starts with either one or both feet in the Centre Circle. The opposing Centre stands anywhere at heart the Centre Third and is free to move and mark players form within. After the whistle is blown the f ootwork rule applies to the centre. Both feet should be in the circle, but if a player has only one foot in the circle, the other mustnt be touching ground outside the circle.The players outside the centre third must run into the centre to receive the ball. A Centre pass must be caught or touched by a player in or landing in the Centre third, if this does not happen then it is considered over a third and a free pass is awarded to the opposing team.After receiving a passWhen a player receives a pass they are not allowed to run/dribble the ball. However they may only bounce or bat the ball once to gain control.Players have to be standing in advance they throw the ball.Players have three seconds to make a pass or shot after catching the ball.Balls may not be thrown over two third lines without being touched by at least one player this will result in a free pass from the second third line the ball crossed.Throw inThe ball is considered out of court when it hits anything outside the co urt area. The ball is returned into play by a Throw-In, this is taken by the opposite team to the one which touched the ball last before going out of play. It is taken from a point outside the line where the ball left the court. The player taking the throw in must have their feet up to but not over the line. The 3 second rule applies when the player is in position and holding the ball.ObstructionIf a player has the ball the defenders foot must be 0.9m (3ft) feet from the landing foot of the player with the ball. The defender can jump and spread their arms, as long as they do not move in towards the attacking player. The defenders are not aloud to deliberately block the attackers view by placing their hands in front of their face or eyes.If a player does not have the ball the defender may be as close as they want, but not touching. The defender must have her arms in a natural position. They cant be outstretched.

Analysis The Four Idols Essay Example for Free

Analysis The Four Idols EssayFrancis Bacons in his attempt named as The Four Idols is derived from the historical expression Novum Organum (1620). In the essay, he attempts to investigate the science of an someone of reality based on their reasoning fallacies by extensive examples and thorough analysis. Francis Bacon has been credited finished creating the scientific techniques, illustrations of this are apparent the presented literature. Bacon in his essay notes the four idols of cave, tribe, theater and marketplace are accountable for hindering the understanding of individuals of the world that surrounds them. The four idols are broken down to logical fallacies founded on individual shortcomings, human reputation, and philosophy ad language. Through his works, he writes to a vast audience in the early seventeenth century with a particularly repetitious tone. Bacons ideas be possessed of withstood the time test and are still prevalent in the contemporary talking to. The 4 idols of tribe are significantly misunderstandings founded on the human disposition unconscious tendencies. Bacon (548) asserts that human understanding usually proceeds from the incompetence, dullness, as well as, senses deceptions.There is usually more to what a person experience compares to what they sense physically, illustrating a sense to a person who is blind is not as fulfilling compared to witnessing it firsthand. Moreover, a person is not able to perceive fully anything in this globe, and this entails the most plaza ideas. Bacons continue through describing the beliefs which are erroneous Bacon (546) notes that even though there shall be a vast numbers as well as, weight of instances to be found on the other side, it either despises or neglects.An additional misunderstanding of the tribe is that humans have tendencies of neglecting data, which does not support what they want so as to reach at desired conclusions. Therefore, humans are faced with misleading information b ased on their human nature. Francis progresses to explain the idols of the cave that are fundamentally misunderstanding, which are based on the individual preferences. Bacon (544) notes that for every person (notwithstanding the errors which are common to the human nature) has a den or a cave of their own, which discolors and refracts the comfortable of the nature.Every person has their own preferences and tastes, and this can easily refract their facts intelligence. Moreover, Bacon (549) writes men usually become attached to specific speculations and particular sciences. In his later years, whizz worked is searching a correlation amid electromagnetism and gravity whilst ignoring the quantum mechanics due to the verity that it was not fitting into his nature perception. Presently, the theories of quantum mechanical theories are in summation unquestionable.This Provides a very good illustration of viewing the globe how one would prefer it rather than how it actually operates. The shortcomings of a person ought to be taken into reflection when observing nature and society. The Market place idol is illustrated as a logical hindrance that is based on language, especially word. Bacon describes the hindrances (545) to be established through the association of men with one another ad the unfit and ill words choice to a greater extent acts as an obstruction to understanding.This understandably indicates that the general populace can be misleading easily through the simple word choice that one uses in describing a specific topic. This is brisk since as is seen the cotemporary world. A popular saying regarding the 9/11 attacks include one mans terrorist is the freedom fighter for the other. This indicates how easily illustrated words can to a greater extent affect judgment. Correspondingly, words cannot illustrate someone or something exclusively. Lavinson indicates in the way to illustrate a flower.He notes that (255) when applying words, batch should not fool t hemselves into deliberating that they are describing fully a real flower this is due to the fact that the word is not thing since one does not have the capability to describe anything completely. This is indeed powerful words which should be actualized. Whilst illustrating anything, there shall be always details that are going to be omitted either well-read or not, the only means through which one can understand truly anything is experiencing it. Hence, words are obstructive and misleading.Moreover, Francis describes the idols of the theater especially understanding founded on tradition, philosophy, or theology. Specifically, Bacon describes which through credulity, tradition, as well as, intelligence has to be attained (545) and later on minds of individuals who have been bruised with theology and religion. This indicates that the general population reality perception is sheltered to their culture and the means of thinking. In his article Villareal starts through describing the si milarities amid Buddhist hell and Greek Valhalla (230) He argues 230 how another person culture can be hell to the other.He describes later that every fleck of reference of a culture is unique, and the definition of a specific event shall be very distinct compared to those observing that fundamentally, the means through which individuals usually perceive an event is entirely distinct compared to the culture that is far and different. Everything ranging from education, religion to the media usually affects the individuals point of reference or the consciousness state. Villareal and Bacon indicate that the barrier can be broken through open-mindedness and awareness.At a first glance, the Ancient philosophies appear digressive to the contemporary times, but by media analysis and personal revelation, it is the modern thought backbone. Fundamentally, Human perception shall be at most times limited. To experience nature entirely one must take into consideration all the idols that hide them that govern the incapability of a person of possessing infinite knowledge appears unrealistic. Nonetheless, the attempt by Bacon is not fully in vain. The general populace should realize that there exist limits to their apprehension and should at all times be opening minded.

How Sleeping Hours Affect Students Studies

How quietnessing Hours Affect Students StudiesSTATISTICAL TECHNIQUES FOR BEHAVIORAL SCIENCE IHOW SLEEPING HOURS AFFECT STUDENTS STUDIES IN UTAR PERAK CAMPUSFACULTY OF ARTS AND social SCIENCETITLE HOW SLEEPING HOURS AFFECTS STUDENTS STUDIES IN UTAR PERAK CAMPUSIndexAbstract Sleep deprivation and unforesightful stay fiber affect the reckon performances of students. The purpose of this statistical study is to determine whether the come of quiescency hours affect the students studies of UTAR Perak Campus. It is hypothesized that participants who support lower cat pile deprivation and higher eternal nap quality will perform discontinue in their studies than those who experience higher quietus deprivation and lower eternal rest quality.Introduction According to Gilbert and Weaver (2010), human bodies anticipate not altogether basic needs of air, water and food to function well but too sufficient sleep as it is important for learning, memory consolidation, critical thoug ht and decision making. For optimal functioning in donnish, sleep is essential. Sleep deprivation is now widely recognized as one of the significant public health issues not just among students but people of all ages and groups. Some shows excessive sleepiness and this is then related to not the quantity of sleep obtained but the quality of sleep. (Gilbert Weaver, 2010) Both sleep deprivation and poor sleep quality are prominent among students because very much they have irregular sleep patterns due to the workloads from their study memorial and also clubs activities. This resulted in them having short sleep lengths in the weekdays and also later wake-up term on weekends. (Gilbert Weaver, 2010) It is recognized by university psychologists that student schoolman performance is macrocosm negatively affected by poor sleep quality and/or sleep deprivation. Though depression is also one of the factor that affects donnish performances of students, sleep quality may even be mo re significant of a factor than depression in affecting students studies. (Gilbert Weaver, 2010) It is found that impact of sleepiness on mood is large as higher negative mood states are being reported by students who fell asleep during class.Research Questions Will quiescence hours affect the academic performance of students of UTAR Perak Campus?Researchers want to find out how different amount of quiescence hours affect the studies of students. What are the factors that affect the quantity of students quiescency hours ?Researchers are interested in finding factors which will affect both the quality and quantity of students sleeping hours which will then leads to affecting the students studies. Will a students sleeping habit being influenced by friends and family?Researchers are keen to know to the extent of how friends and family will affect a students sleeping habit. How many hours of sleep do the young-begetting(prenominal) and effeminate students need per day ?Researche rs want to study about the amount of sufficient sleeping hours required by female and male students. What are the differences in CGPA brands of both male and female students according to the amount of sleeping hours they have ?The researchers are keen to study the differences in CGPA make obtained by both genders of students according to the amount of sleeping hours they have.Literature ReviewSleep is very important to a human beings health. The consequences of sleep manifest in both health and performance. The relationships between sleep and performance have been studied in many different fields including human science, medicine, psychology, education, and subscriber line and etc. Sleep-related variables for instance sleep deficiency, sleep quality, sleep habits have been shown to influence the performance of students (Lack, 1986 Mulgrew et al., 2007 National Sleep Foundation, 2008 Pilcher Huffcutt, 1996 Rosekind et al., 2010). According to Weitzman et al. (1981) , Delayed Slee p Phase Syndrome (DSPS) was delineate into three big categories which are long sleep latency on weekdays (normally fall asleep between 2 a.m. to 6 a.m.), normal sleep length on weekends (usually sleep late and wake up late on weekends) and difficulty in staying asleep. These sleep problem is common and is present in students virtually the world.Results indicates that in the U.S., 11.5% of undergraduate students were found to have DSPS (Brown, Soper, Buboltz, 2001). Not only that , Australian studies found the prevalence of DSPS in students (17%) to be higher than in adults (6-7%) (Lack, 1986 Lack, Miller, Turner, 1988). Studies related to DSPS have also been conducted in other countries such as Japan, Norway, and Taiwan (Hazama, Inoue, Kojima, Ueta, Nakagome, 2008 Schrader, Bovim, Sand, 1993 Yang, Wu, Hsieh, Liu, Lu, 2003). Furthermore, In Lacks (1986) study, the DSPS group experienced sleepiness on weekdays more often rather than the non-DSPS group. In addition, , it was fou nd that members of the DSPS group performed at a lower level academically when compared with the non-DSPS group when course grades were examined . In a more new-fashioned study, Trockel et al. (2000) found that first-year college students with lower GPAs reported later bedtimes on weekdays and weekends and later wake-up times on weekdays and weekends.On the other hand, the relationship between sleep and academic performance was reviewed in other studies . Approximately 103 studies related to sleep loss, learning capacity, and academic performance samples were carried out among students in different university by Curcio, Ferrara, and Gennaro (2006). According to Curcio, Ferrara, and Gennaro (2006), sleep loss was negatively correlated with academic performance. Results indicates that sleep-deprived students performed poorly on learning capacity skills for instance attention, memory, and problem-solving tasks, and that the lack of sleep therefore indirectly affected their academic pe rformance. Sleep deprivation is a term meaning loss of sleep Drummond and McKenna (2009) . Moreover, sleep loss resulted in daytime sleepiness that was also correlated with poor academic performance studies showed a significant relationship between lower GPA and lack of sleep among college students. The Multiple Sleep Latency Test was an performer used to evaluate daytime sleepiness, which has been used by previous researchers (Carskadon, Harvey, Dement, 1981 Fallone, Acebo, Arnedt, Seifer, Carskadon, 2001 Randazzo, Muehlbach, Schweitzer, Walsh, 1998).On the other hand, another study was conducted to determine the various sleep patterns in health check students appearing in various ongoing professional at Shifa College of College of Medicine, Islamabed and to find out relationship between number of hours of sleep before an examination with academic performance in relevant exam. Majority of the students had reduced sleep in exam days and its reason was found to be studying late at night before paper and academic performance. There have been various reasons for decreased sleep in university and college students including watching TV and using the internet. A study done in a Pakistani medical university indicated that 58.9 per cent of the university and college students the most common cause of sleep deprivation was watching television and listening to medicinal drug affects the students slept less than 8 hours a day . In addition, stress, in university and college students, is also a very essential contributing factor in inability to sleep at night. Consumption of caffeine , pain killers, substance abuse and smoking at night to keep them awake is also another trend seen among students. This greatly contributes to sleeplessness at night among students and affects their academic performances adversely. (Oshodi OY, Aina OF, Onajole AT, Omvik S, Pallesen S, Bjorvatn B, Thayer J, Nordhus H. Qureshi AU, Ali AS, Hafeez A, Ahmed TM ). Moreover, the study showed th at students who achieved good grade (A, B) were those who slept for more than 7 hours but those who majority failed in exam, were also loosely those who slept less.However, a similar study done in USA showed that students who had struggling grades (Cs Ds / Fs) were those who slept significantly less than those who scored A and B grades ( Wolfson AR, Carskadon MA). According to the study, student slept an average of only 4.74 hours before the exam and females slept less (4.71+1.82 hours) as compared to males (4.77+3.27 hours ). This was similar to a cross sectional study done in Sao Paulo, which showed that boys slept about 390 minutes. However, their academic performance was not affected by the disturbance in the sleep cycle.Furthermore, another research was done with 103 samples of undergraduate classes of University of Minnesota.This study reveal unhealthy sleep habits into two categories which are quality and quantity of sleep. In this study, the survey asked questions related to their sleep habits in term of quality and quantity of sleep which separately measured in order to break up the term of unhealthy sleep habits and analysed this topic by using a different method acting compare to past research. In this research, the researchers found that sleep quantity and academic performance are related. This research shown that have the relation between part of sleep deprivation measures for the average week and the average amount of sleep obtained in a night and GPA. This result helps the college student by practical applications. From this research, the researchers found that amount of sleep and academic success are positively correlated, although cannot conclude that sleep better, score better in exam.MethodologyParticipants of the StudyThere are 50 participants in this study. They are degree students from University Tunku Abdul Rahman (Kampar) who are from faculty of art social science (FAS), faculty of business and finance (FBF), faculty of information c ommunication and engineering (FICT), institute of Chinese studies (ICS) and faculty of science (FSC). Their age range is from 20-24. Besides, there are 5 male and 5 female from each faculty.InstrumentsOur questionnaire consist of 15 closed-ended questions and each question involved different level of measurement such as nominal, ordinal, interval and ration scale.Our demographic details are gender, age, courses of studies and CGPA comprised in the questionnaire.Sleep measures consists measurement of Total Sleep Time (TST), Sleep Onset Latency (SOL), Sleep Efficiency (SE) and Wake After Sleep Onset (WASO). It is determined by the Cole-Kripke (1992). Total Sleep Time (TST), which is duration of time actigraphically-determined as sleep within a 24-hour period, including daytime and nighttime periods of sleep. Sleep Onset Latency (SOL), which is time used between getting into bed and falling asleep, calculated as the time used from the start of actigraphically-determined inactivity to t he first minute scored as sleep. We only refer TST and SOL among the four measurements in our questionnaire (question 2 and question3).To measure the sleep quality of students, we decided to use the Adult SleepWake Scale (ADSWS). It is a self-report pencil-and-paper measure of sleep quality consisting of ve behavioral dimensions, which are Going to Bed, Falling Asleep, Maintaining Sleep, Reinitiating Sleep, and Returning to Wakefulness. The questionnaire consists of time taken to fall asleep at night (range from 1 hour), the amount of sleeping hours required in order to function well on the following day (range from ProcedureWe are curious about how sleeping hours affect students studies, so we came out our research questions. After that, we set our questionnaires and printed out for the participants. We select randomly 5 male and 5 female from each faculty. Our questionnaire also take inform consent for the participants. On average, each participant took about 10 to 15 minutes to complete our questionnaire. Once they completed their questionnaire, we collect the data immediately.Data Analysis escort 1.Amount of sleeping hours affecting students studiesFigure 1 shows the CGPA scores obtained by students of UTAR Kampar campus according to the amount of sleeping hours they have. Students are likely to obtained highest CGPA score range of 3.50 to 4.0 when they obtained seven to eight hours of sleep per day.Figure 2.Factors affecting the quality and quantity of students sleeping hoursFigure 2 shows the factors that affect the quality and quantity of students sleeping hours. 34% of the total of 50 students chose homework as the biggest factor that affects their sleeping hours whereas only 6% of them chose co-curriculum as the factor that is affecting their sleeping hours. Other factors include being night owls, socializing with friends and time managementFigure 3.Will a students sleeping habit being influenced by friends and family.Figure 3 shows that 11 male and 13 female students stated that their sleeping hours were influenced by friends and family while 4 male and 7 female students stated that their sleeping hours were not being influenced by friends and family.Figure 4.Amount of sleeping hours required between different genders of studentsFigure 4 shows that 13 male and 11 female students stated that they require seven to eight hours of sleep per day while only 2 male and 1 female students require less than five hours of sleep per day.Figure 5 shows the CGPA score obtained by both male and female students according to the amount of sleeping hours per day.Figure 5 shows that 10 male and 6 female students who had seven to eight hours of sleep per day score an average CGPA at the range of 2.20-2.99 while only 2 male students who had the same amount of sleeping hours score the lowest range of CGPA at 0.00-1.99. Only 1 male student who had less than five hours of sleep had a CGPA score range of 2.20-2.99 and 1 female student who had the sam e amount of sleeping hours had a CGPA score range of 3.00-3.49.

Using Thin Layer Chromatography To Monitor Reactions Environmental Sciences Essay

Using Thin Layer Chromatography To Monitor Reactions Environmental Sciences proveThin layer chromatography (tender loving c be) is a very useful technique for monitoring reactions. It evoke alike be apply to deter instante the proper solvent constitution for performing separations development column chromatography. TLC stationary anatomys are usu everyy alumina or silica. They are icy for standard experiments or non-polar for reverse phase chromatography. The restless phase is a solvent whose polarity is chosen by the person conducting the experiment. In most laboratory work standard phase silica plates are used. Different compounds allow travel dissimilar distances up the plate de drop a lineding on the polarity of the components of the mixture. The more polar compounds will be more attracted to the polar silica gel and travel shorter distances on the plate. Mon-polar substances will s create verballyd more time in the mobile phase and as a result will travel larger di stances on the plate. The measure of the distance a compound travels is c all(prenominal)ed the retention factor (Rf ) value.The retention factor, or Rf, is defined as the distance traveled by the compound divided by the distance traveled by the solvent.For example, if a compound travels 2.1 cm and the solvent front travels 2.8 cm, the Rf is 0.75The Rf for a compound is a constant from one experiment to the next provided if the chromatography conditions below are similarly constantsolvent system chemosorptive burdensomeness of the chemisorptiveamount of material patchedtemperatureSince these factors are difficult to keep constant from experiment to experiment, relative Rf values are generally considered. coition Rf means that the values are reported relative to a standard, or it means that you compare the Rf values of compounds run on the akin plate at the same time.1.1 Thin Layer ChromatographyThere have been a numbered of important milestones in the evolution of chromatograp hy in the last 100 years. severally of these milestones has signalled the start of an important branch of chromatography. Some examples of these are partition chromatography (1941), gas chromatography (1951-1952), high performance liquid chromatography (mid- 1960s), capillary electrophoresis (1980) and capillary electrochromatography (past decade).In all the chromatographical techniques mentioned, separation is carried out in a column. However, it is also possible to carry out separations on a planar surface. Two examples of this are theme chromatography (1944) and thin-layer chromatography (1937-1938). Thin-layer chromatography (TLC) replaced paper chromatography as the most popular, routine chromatographic technique.TLC was first used in 1937 to 1938 by Nikolai A. Izmailov and Maria S. Shraiber at the Institute of Experimental chemists shop of the State University of Kharkov. At the time Izmailov was the head of the institute and Shraiber was his graduate student. They were se arching for a order for the rapid analysis of galenic pharmaceutical preparations (plant extracts). As mobical column chromatography would have taken too much time they felt that if the absorbent would be on the watch in the form of a thin-layer on a tripe plate. They believed that it would behave like a column but the characterization time would be much shorter. They coated microscope slides with a sus savesion of various adsorbents (calcium, magnesium and aluminium oxides). They deposited one drop of the sample consequence on this layer and added one drop of the same solvent used in a column to ruin separation. The test was a success as the stray sample components appeared as concentric rings that fluoresced in various colours under a UV lamp. They showed that the sequence of the concentric multicoloured rings on the plate would have been identical to the sequence of coloured rings obtained on a normal chromatographic column. They called this technique feeling chromatogra phy and the result on the microscope slides ultrachromatograms.The paper on this experiment was published in a Russian pharmaceutical journal that was practically inglorious outside the then Soviet Union. Its abstract was included in a Russian review journal and through it in chemical Abstracts. It was then tape by M. OL. Crowe of the New York State Department of Health. He then adapted the technique for his own use. Crowe prepared the adsorbent layer in a Petri dish, added a drop of the sample solution in the centre and then added the developing solvent dropwise until sufficient separation was obtained.In 1947 T.I. Williams described a further value of the method of Izmailov and Shraiber in his textbook on chromatography. He prepared the adsorbent-coated glass plates in the form of a sandwich. The adsorbent layer was covered by 2 glass plates and had a small hole which the sample drops could be employ through.Meinhard and Hall made the next major step in the development of TLC at the University of Wisconsin. They used corn starch, which acted as a binder, to hold the coating on the glass plate and added a small amount of Celite powder to the adsorbent particles to improve the consistency of the layer. They called this surface chromatography. They used it to separate inorganic ions.Modern TLC started 50 years ago with the work Department of Agriculture harvest-feast and Veget up to(p) laboratory in Southern California. He investigated the spirit components of the juices of citrus fruits. However, he stated that very large volumes had to be processed because the amount of flavour material was extremely small. Another problem was in finding an analytical method for the investigation of the juice concentrate story.He followed the method of Meinhard and Hall that he read in Chemical Abstracts. However, instead of adding just a drop of the developing solvent he create the plates as in paper chromatography. The plates were real in a closed chamber and one s ide was dipped into the solvent. The solvent then ascended through the plate by capillary action. It carried with it the sample components and they were separated as a result. The experiments carried out were published and are considered the start of modern TLC.Egon Stahl was responsible for TLC becoming a universally accepted technique. He was also the first to use the term thin-layer chromatography to characterize the technique. This choice of name was almost immediately accepted.Stahl investigated various essential oils and obtained good results using adsorbent-coated glass plates. However, neither the method nor the adsorbent to be used had been optimized. Also, the adsorbents had to be modified and treated before they could be used for the coating of plates. Stahl started investigating the operational parameters and the adsorbent preparations. In the echo of 1958 his efforts were fulfilled as the necessary basic instrumentation, made by Desaga and silica gel G according to Sta hl for TLC, made by E. Merck were both introduced at the internationalist Achema exhibition of chemical equipment in Frankfurt. Stahl also published an article outlining the use of the system and a wide range of operations. Because of this standardized method TLC became a widely used laboratory technique. He also went on to publish a TLC handbook in 1962.Although TLC had a wide application it was still thought to be a qualitative technique for the analysis of simple mixtures. As a result advances were directed toward improving the technique. Instrumentation which permitted more precise spotting of the sample onto the plates and the quantitative evaluation of the separated spots was developed. Faster analysis and higher separation power was also achieved. As a result of the higher performance ability the name was change to high-performance TLC (HPTLC) by R.E. Kaiser, who was instrumental in its development.The particle size and range of the adsorbent was the main difference between TLC and HPTLC. The silica gel for TLC had broad particle sizes of 10-60m with an average of 20m whereas HPTLC has an average of only 5m. the HPTLC plates were also smaller in comparison with TLC plates, 10 x 10cm and 20 x 20cm respectively. The improved method and design allowed reduction in the diam of the starting spots. These improvements lowered the analysis time and increased the efficiency. Problems arose with flow rate which Kaiser overcame by applying pressure to the TLC plate. This in turn led to forced-flow TLC. collectable to the constant condensation-evaporation process associated with developing TLC plates in developing chambers problems asshole be encountered because of the changing velocity of the mobile phase. To overcome this forced-flow TLC (FFTLC) was developed by Tyihk, Mincsovics and Kalsz. In this method the spotted plates (dry) are placed into a pressurized development chamber. The stationary-phase layer is tightly covered and sealed on its side by an elast ic membrane and pressurized by an inert gas or piss filling up the cushion above the layer. The mobile phase is delivered via a essence at a constant velocity through a slit in the membrane to the stationary phase. There are various configurations which can be handled using this method.TLC is a very simple technique. As a result very little instrumentation is needed. Application of samples to the stationary-phase is carried out using a micropipette or syringe. The developing chambers are simple glass structures. Detection is carried out by visual inspection or made visible by spraying the plate with reagent. Also, a wide variety of precoated plates are available so coating equipment isnt needed.In more advanced systems the samples may be spotted by automated loading devices (dosimeters). This allows the application of small and uniform sample spots. More sophisticated developing chambers are also available (FFTLC). The plates can be scanned by densitometers and quantitatively anal ysed using absorbance or fluorescence measurements. Chromatograms with peaks of the individual separated spots recorded against the length of the plate are produced with much(prenominal) analyses. Their area is also a parity to the amount present. More complex systems can also be created by combining TLC systems with other systems such as potful spectrometry and Fourier transform infrared.1.2 Ink AnalysisInk analysis is a very important forensic procedure. It can reveal useful information astir(predicate) questioned document. Modern inks contain many substances which are aimed at improving the ink. The most important component of the ink is the colouring material. It comes in the form of a dye, paint or a combination of both. Dyes are soluble in the liquid body of the ink, also known as the vehicle. Pigments are finely ground multi-molecular granules that are insoluble in the vehicle. The vehicles composition affects the flowing and drying characteristics of the ink and can cons ist of oils, solvents and resins.1.3 Chromatography StudiesDjozan et al developed a new and fast method for the variousiation of inks on a questioned document. They designed specific image analysis software for evaluating thin layer chromatograms. They sampled forty-one blue eggspoint draw ups which were purchased from their local markets in Iran ( knock back 1).They first wrote a circle of diameter 5 mm uniformly by pen on a paper. One fourth of this was then punched out for declivity. They carried out extraction in 1 ml glass tubes and added 0.1 ml of mgrain alcohol. This was then modishly shaken for 1 min. the ink component was then fully dissolved in methanol. The supernatant methanoic solutions were then used to spot the TLC plates. A space sample of paper with equal dimensions was also treated in the same way. prorogue 1. List of blue ballpoint pens studiedList of blue ballpoint pens studied1 Cello pyramid 0.7 mm fine TC ball2 OBA3 AIHAO4 Bic 015 Cenator6 PARKER7 A.T.CRO SS FINE8 Pelikan accommodate 9189 Marvy SB-10 1.0 mm10 Bic 0211 PIANO watch glass12 My pen 2001 PENS High Quality Bluce CE13 AIBA14 STAEDTLER Stick 430M A IRAN15 Reynolds Medium 048 France16 EIFEL Elegance17 CASPIAN STICK 2001 M18 STABILO liner 30819 FABER-CASTELL 1.0 mm Medium (transparent)20 BIC 0821 Bocheng A-10022 SCHNEIDER TOPS 505 M Germany23 FIBER-CASTELL 1.0 mm Medium24 MILAN PI 1 mm25 Reform26 PAPER = MATE FLEXGRIP ultra MED27 PARKER UK28 CANDID-DINI 285329 STABILO-galaxy 818 M30 No name31 No name32 Zebra Rubber 10133 SANFORD SAGA34 Bensia35 Girls36 EUROPEN37 PARS swiss Refill 60638 STAEDTLER stick 430 M TBRITAIN39 Lus HF 50040 No name41 STABILO bill 508TLC analysis was carried out on Merck (Darmstadt, Germany) 20 cm x 20 cm silica gel 60 TLC plates without fluorescent indicator. The plates were activated at 60 C for 20 min and immediately spotted after cooling in a desiccator. The plates were developed in a developing chamber. The mobile phase used was ethyl ethanoate/ ab solute ethanol/ distilled water (703530, v/v/v). Chromatographic development of the plates was carried out at room temperature for 40 min. All mobile phases were prepared daily with analytical grade chemicals. Enough was prepared to supply the tank for each run. The plates were air-dried after development. The separated compounds were visible on the plate by their natural colour and the plates were scanned into a computer using an office scanner.An IBM compatible PC (Pentium IV) with a 2.6 GHz microprocessor, 256 MB random access memory (RAM) and a hard disk with 40 GB capacity for external storage was used for processing the colour images. The computer was equipped with an on-board graphic card (NviDiA Geforce 7300LE) and a scanner (CanoScan 4200F) was connected to the computer for scanning (300 dpi) TLC plates as digital images. The images were saved as bmp files. Matlab (Version 6.5, The Math Works, Inc.) was used to write a new syllabus to process the previously saved images.Pr evious studies indicated that Pyridine is the solvent used with ballpoint pen inks. Djozan et al preformed extraction with different solvents using various extraction modes. These modes were submersion of paper into solvent and simple agitation for 1 min, ultra-sound assisted extraction and micro-wave assistance extraction. The results showed that the immersion of paper into methanol or pyridine and simple agitation resulted in complete extraction of the inks from paper (Table 2).Table 2. List of solvents used for extraction of ink components from paperSolventSolubility of ink coloursEthyl ethanoate rayonEthanolAcetic acidAcetoneButanol1,2-DichloroethaneButyl acetate rayonTetrachloroethaneAcetyl acetateCyclohexane methanolPyridine roughlySlightlySlightlySlightlySlightlySlightlySlightlySlightlySlightlySlightlySolubleSolubleNo improvement was found using ultra-sound or micro-wave assisted extraction. Methanol was chosen as the extraction solvent due to the safety of the solvent. The selection of the plate was down to the fact that silica gel plates provided the best resolution of dye spots. They selected five mobile phases (Table 3) and found that ethyl acetate/ absolute ethanol/ distilled water (703530, v/v/v) was effective in separating nearly all the dye mixtures. The spot capacity obtained was more than 15.Table 3. Different solvent systems used to develop plateSolvent SystemRatioSpot capacityButanolethanolH2OEthyl acetatecyclohexanemethanolNH3Ethyl acetateButanolNH3Ethyl acetateethanolH2OTolueneacetoneethanolNH35015107015105603557035303060729510155Fig. 1. Typical TLC results of 10 different ink samples (Djozan et al, 2008)Fig. 1. shows a typical chromatogram that they achieved in their experiment. To avow complete separation of all components in the studied sample, dickens-dimensional (2D) TLC was carried out using various solvent systems. The results proved that the one-dimensional (1D) TLC is able to provide sufficient separation.The first stage carri ed out was colour image normalization. A function of the input images was computed that is invariant to confounding scene properties but was discriminating with respect to desired scene information. The calculation is as followsStage 2 is to compute a colour image profile. The intensity profile of an image is the rear intensity values taken from regularly spaced points along a line segment in an image the intensity values are interpolated for points that dont decrease on the centre pixel they computed an intensity profile for r, g and b images along the line passing through the centre of the image on the chromatographic development straight of each ink spot.Fig. 2. RGB characteristic of an ink after TLC (Djozan et al, 2008)In stage 3 the colour image profiles were correlated. The intensity profiles were considered as sequences and the normalized cross-correlation of sequences were computed. Cross-correlation is a measure of similarity of two signals. It is used to find features i n an unknown signal and compared to a known signal. It is measured as follows for discrete functionsEq. (1)For image-processing applications in which the brightness of the images can be due to lighting and exposure conditions, the images can be first normalized. It is calculated as followsEq. (2)Stage 4 involved calculate image similarity. The weighted mean of and were computed as followsEq. (3)The ability of the method to differentiate between various blue ballpoint pens was evaluated by comparing the similarity of different inks according to Eq. (3).Fig. 3. Screen shot of Matlab software running (Djozan et al, 2008)Fig. 4. All possible combination of comparing inks with TLC-IA (Djozan et al, 2008)In 2006 Liu et al published a paper on the variety of black gel pen inks by ion-pairing high-performance liquid chromatography. They stated that black gel inks usually contain several dye components. These components all have different colours and are mixed together proportionally to g ive the black colour.They used reverse-phase ion-pairing high performance chromatography (RP-IP-HPLC). It was done in such a manner as the dyes couldnt be reversed on the C18 column due to their high polarities. The maximum UV assiduousness bands of the black gel pen inks obtained were between 500 and 700 nm. The wavelength of the detector was set to 580 nm as most of the dyes had a maximum UV adsorption near 580 nm.They investigated the influence of both quicksilver(a) and non-volatile ion-pairing reagents on the HPLC analysis of black gel pen ink dyes. All the reagents had different alkyl chain, ammonium acetate, triethylamine (TEA), tributylamine (TBA), dihexylamine (DHA) and tetrabutylammonium bromide (TBABr). The results revealed that the dyes were nearly not retained using ammonium acetate or TEA as the ion-pairing reagent. Using TBABr, TBA and DHA as the ion-pairing reagent, individually, the dyes were separated. TBABr was selected as the ion-pairing reagent as the retentio n times were shorter than the others and sharper peaks were obtained.They also investigated the buffer solution concentrations and the effect of pH on the separation. The optimum result was 40 mmol/L TBABr buffer solution (pH 7) with acetonitrile as the organic modifier for IP-HPLC analysis and an identical proportion of the buffer and acetonitrile (v/v = 4060) at a flow rate of 1.0 mL/min. these optimum conditions were used to separate 50 dye-based black gel pen inks by IP-HPLC.Liu et al carried out another study on ion-pairing HPLC in 2006. This time, however, they studied the degradation of blue gel pen dyes and also used electrospray bicycle-built-for-two mass spectrometry.They used ion-pairing reversed phase liquid chromatography as the inorganic compounds they were analysing have weak retention on the ordinary reversed stationary phases when separating on HPLC. This is due to their high polarities. The UV detector was set at 580 nm for the analysis as most dyes have a normal maximum absorption near 580 nm. The UV absorptions of the fluorescence whitening reagents in paper are usually below 500 nm and they had no interference for the detection of the gel pen dyes at 580 nm.Fig. 5. Chromatograms of blue gel pen inks using different ion pairing reagents (Liu et al, 2006)The tested various mobile phases eluent A eluent B (acetonitrile) = 5050 (v/v) eluent A was the buffer of ion pairing reagent with concentration of 40 mmol L1 (pH 7.0), and the ion pairing reagent was (a) ammonium acetate, (b) TEA acetate, (d)TBA acetate, (e) DHA acetate and (f) TBABr, respectively. (c) Ammonium carbonate as eluent A (40 mmol L1, pH 9.5) and eluent Aeluent B (acetonitrile) = 5050(v/v). they found that 10 mmol-1 TBA acetate (pH 7.0) was suitable ion-pairing agent for the purpose and ink samples stored in different conditions were analyse by IP-HPLC. Significant changes of ink composition were observed. The noticed that the natural aged inks had the similar but weaker degrad ation trend than the light aged inks. They used HPLC-MS/MS with ammonium carbonate as ion-pairing reagent to obtain the information of the light aged inks and their photodegradation mechanism.In 1994, Varshney et al analysed ink from typed al-Quran of electronic typewriters by HPTLC. They used script from seven electronic typewriters. They used the resultant Rf values and in-situ visible spectra of each resolved band of all the chromatograms indicated that the same chemical composition is being used in six typewriter ribbon inks. However, the seventh one is completely different.Fig. 6. Wavelength maxima values of in-situ visible spectrum bands of electronic typewriter scripts (Varshney et al, 1994)Fig. 6. shows the densitograms obtained after scanning and integration of the chromatograms of tracks of individual typewriters and blank paper. The seven electronic typewriter inks could be categorised into two chemical groups after analysis. The first group resolved the sample to four bands including the base. The second group did not resolve the samples at all with the solvent systems used.Several varieties of blue ballpoint pen inks were analysed by HPLC and IR spectroscopy by Kher et al in 2006. The chromatographic data extracted at four wavelengths (254, 279, 370 and 400 nm) was analyzed individually and at a combination of these wavelengths by the soft independent modeling of class analogies (SIMCA) technique. They used principal components analysis (PCA) to estimate the separation between the pen samples. Linear discriminant analysis (LDA) measured the probability with which an observation could be assigned to a pen class. The best resolution was obtained by HPLC using data from all four wavelengths together, differentiating 96.4% pen pairs successfully using PCA and 97.9% pen samples by LDA. PCA separated 60.7% of the pen pairs and LDA provided a be classification of 62.5% of the pens analyzed by IR. They stated that HPLC coupled with chemometrics provide d a better discrimination of ballpoint pen inks compared to IR.Kher et al effectively combine LDA and PCA to classify the HPLC and IR data. PCA gives a general idea of how different a given pair of pens is, whereas LDA can quantify the predictive ability of a generated classification model. The two techniques of PCA and LDA were shown to be complimentary to each other. The PCA and LDA results indicated that although IR cannot differentiate between all classes of pen inks, it can still provide a reasonable discrimination, which can be enhanced further by improving the quality of the spectra. The analysis of such an enhanced IR data with chemometric analyses would provide a valuable non-destructive turncock for forensic analyses.Raman Spectroscopy StudiesMazzella and Buzini used Raman spectroscopy to analyse blue gel pen inks in 2004. They sampled 55 blue gel pens. They first separated them into two groups using a preliminary solubility test in methanol. They discovered that 36 were pigmented inks, which arent soluble in methanol, and 19 were dye-based inks, which are soluble in methanol.They applied Raman spectroscopy to the 36 pigmented blue gel inks. Raman spectroscopy is a non-destructive technique. Spectra were first obtained using the 514.5 nm argon ion laser which proved the observation of 4 different groups. They then used the 830 nm NIR diode laser and divided the inks into three groups. They then combined the two lasers and a separation into 5 groups was obtained.They then act to identify the pigments contained in the gel by comparison to standard pigments. Two main pigments were detected in the analysed samples PB15 and PV23. PB 15 is pigment blue 15 and belongs to the class of phthalocyanines. PV23 is the pigment violet 23 and belongs to the class oxazines. The argon laser allowed the detection of a mixture of PB 15 and PV 23. This was a better result than using the NIR diode laser.The results showed that the same gel pen ink (same model and brand ) from different geographical locations showed the same Raman spectra. However, it was stated that the Raman technique obtained low discriminating values.2. Materials and mode2.1 MaterialsBlue ballpoint pensMerck silica gel 60 TLC plates (20 cm x 20 cm)MethanolEthyl acetateEthanol (absolute)PaperDessicator maturation chamberPuncherGlass tubes (0.1 ml)Capillary tubes2.2 Experimental13 blue ball-point pens (Table 1) were bought from a number of different shops in the town. A circle with a diameter of 5mm was written by the pen on paper. One fourth of it was punched out for extraction. The samples are placed in 1 ml glass tubes. 0.1ml of methanol was added and vigorously shaken for 1 min. The ink component was fully dissolved in methanol. The supernatant methanoic solutions were used for spot application on TLC plate. A blank of paper only is also treated as was a control which was a permanent marker. TLC analyses were preformed using Alugram 20 cm x 10 cm silica gel/UV plates (Macher ey-Nagel). The plates were activated at 60C for 20 min and immediately after, cooled in a desiccator, and spotted. The plates were developed in a horizontal developing chamber. The solvent system included ethyl acetate/absolute ethanol/ distilled water (703530, v/v/v). phylogenesis was preformed at room temperature for 40 min. All mobile phases were prepared daily. After development the plates were air-dried. All 13 different pens were tested in triplicate. Retention factors were calculated using the results from the plates and photographs taken using a digital camera were loaded onto the computer and analysed using image analysis software.Table 1List of pens analysed keep downDescription1No Brand (blue)2Pilot G-2073BIC ReAction4BIC Medium (Bought in Tesco)5BIC Medium (Bought in Dunnes)6No Brand (Purple)7Staedtler Stick 430M8Roller Pen9Papermate 1.2M10Scripto Stick Pen11Papermate Write Bros.12 nourish Touch13No Brand (Tesco Click Pen)3. Results and DiscussionBefore carrying out the experiment it needed to be researched. This research pointed out the importance of the correct solvent to remove the ink from the document. Djozan et al used methanol as their choice of solvent after considering other solvents (Table 2). They stated that Pyridine was the reported solvent used with ball-point pen inks. However, they carried out extractions with different solvents using various extraction modes. They realised that immersion of the paper into methanol with agitation resulted in complete extraction of the inks from the paper. Methanol was also chosen because of its safety.Table 2List of solvents used for the extraction of ink components from paperSolventSolubility of ink coloursEthyl acetateSlightlyEthanolSlightlyAcetic AcidSlightlyAcetoneSlightlyButanolSlightly1,2-DichloroethaneSlightlyButyl acetateSlightlyTetrachloroethaneSlightlyAcethyl acetateSlightlyCyclohexanSlightlyMethanolSolubleOyridineSolubleDifferent concentrations of the solvent system (Table 3) were analys ed to see which gave the greater separation. It was found that the concentration given by Djozan et al, (ethyl acetate, ethanol, and water (703530, v/v/v)) gave the best results. The Alugram silica Gell/UV plates were also found to work better than the suggested, Merck silica gel 60, plates without fluorescent indicator.Table 3Concentrations of solvent system investigatedNumberSolvent system1ethyl acetate, ethanol, water (703530, v/v/v)2ethyl acetate, ethanol, water (703035, v/v/v)3ethyl acetate, ethanol, water (702540, v/v/v)4ethyl acetate, ethanol, water (704025, v/v/v)Table 4Retention factors for all separated componentspenspot 1spot 2spot 3spot 4spot 5SolventRF1RF2RF3RF4RF51.170730.9589041.270730.9589041.270730.9589042.16269730.84931581.241942.26269730.84931581.241942.36269730.84931581.241943.1576062700.814286

Debromination and Bromination of Cholesterol

Debromination and Bromination of CholesterolBromination/debromination which is an important complete reception that aims in shade of crude cholesterin from impurities which include 3-cholestanol, 7-cholesten-3-ol, and 5,7-chlestadien-3-ol was performed in a laboratory scale for both weeks. Due to steric constraints, only cholesterol reacted with bromine and cryst exclusivelyized from the solution making it possible to be separated (Feiser, and Williamson 63). The dibromocholesterol formed is regenerated by reacting with Zinc dust. In addition, three methods were used to evaluate the effectiveness. These were Sodium Iodide screen, Silver Nitrate visitation, and Sulfuric acid mental testing. NaI test showed a positive response as color changed to yellow. The formation of the precipitate also indicated a positive result. The sodium iodide reagent reacted with 1 and 2 alkyl halides through an SN2 mechanism.On the other hand, the argent process reagent reacted with 2 and 3 alk yl halides through an SN1 mechanism. proscribe results were observed for both the commercial cholesterol and 1-chloro simplyane (Zubrick 38). Conversely, the t-butyl chloride gave a positive result for the AgNO3test and a ban result for the NaI test. The synthesized cholesterol was 0.29 gram and the theoretic yield was 1.08 gram. This gave a percent yield of 26.9 gram. Although this was a low yield the tender loving care analysis indorseed a high purity of the synthesized cholesterol. The melting point of the synthesized cholesterol and commercial cholesterol seems to fall in the same range. This confirms the purity of the synthesized cholesterol. TLC analysis was carried out to confirm the purity of the analysis. The distance traveled by commercial cholesterol was 5.5 whereas that travelled by the synthesized cholesterol was 4.6. The absence of other spots on the TLC dwelling confirms that there were no contaminations flummox in the sample.IntroductionCholesterol is an import ant steroidal compound found in both animals and plants. Despite the fact that cholesterol causes diseases, it plays a vital role in life. For example, cholesterol is the main structural component in cell walls and in myelin sheath formation. It is also a major precursor for most steroid hormones. Crude cholesterol is isolated from natural sources and various methods have been used in its purification. Crude cholesterol contains roughly 3-5% contamination. Some of the contaminants are 3-cholestanol, 7-cholesten-3-ol, and 5,7-chlestadien-3-ol shown below.Some common contaminants of commercial cholesterol The main objective of this experiment was to purify commercial cholesterol victimization organic reaction chemistry, including the use of the electrophilic addition. For complete purification of cholesterol from the above impurities is achieved by a reaction of bromine with cholesterol to generate dibromocholesterol. Because of the steroid mob structure present in these compounds t hat causes steric constraints, only cholesterol reacts with bromine to form an insoluble diaxial dibromo compound through electrophilic addition. On the other hand, cholestanal does not react with bromine and the other two contaminants are dehydrogenated by bromine leading to formation of soluble dienes and trienes respectively. The dibromo-cholesterol precipitates as a solid leaving the other impurities in the reaction solvent. A purification step such as solvent washing or crystallization is carried out to separate the solid from the impurities. The solid dibromo-cholesterol is thence reacted with zinc in enact to regenerate pure cholesterol.Reaction Scheme for the Bromination/Debromination of CholesterolTo test the effectiveness of this reaction three different chemical tests namely sodium iodide in acetone, silver nitrate in ethanol test, and sulfuric acid test, were performed. Each of these tests is selective for a specific functional group. Dibromocholesterol contains both pr imary and secondary alkyl halides and reacts with a sodium iodide in acetone and silver nitrate in ethanol to form a precipitate or a cloudy solution. In addition, the posture of double bonds in dibromocholesterol in form of alkene makes it possible for the formation of a fluorescent green sulfuric acid layer and a expiration chloroform layer when reacted with sulfuric acid (Landgrebe 78).Material and Methods1g of commercial cholesterol was added to a 25 mL Erlenmeyer flask. 7 mL t-butylmethyl ether was measured with a graduated cylinder and added to the flask containing the cholesterol and a magnetic stir bar. A urine bath was then set up on the hot plate in the hood. The Erlenmeyer flask contain the reaction solution was inserted into the water bath and clamped as shown below. The heat and the stirrer were turned on and gently heat until all the cholesterol dissolved in t-butylmethyl ether.The flask was removed from the water bath after all the cholesterol was completely dissol ved and allowed to cool to room temperature. later the cholesterol solution was cooled, the flask was clamped to the ring on the hot plate as shown in figure 4 and stirred without heating. A burette was then used to dispense 5 mL of bromine solution into the flask. A precipitate solution formed almost immediately.The water bath was replaced with ice and bug water and the reaction solution stirred intermittently with a glass stir rod for 10 legal proceeding to complete the crystallization of the product. About 20 mL of the t-butylmethyl ether acetic acid solution was then dispensed in a clean 50 mL Erlenmeyer flask which was clamped to a ring stand and allowed to cool in the ice bath. A vacuum filtration was done using a Buchner funnel and filter paper. The solid in the filter was washed using 10 mL of the cooled solution of t-butylmethyl ether acetic acid and then with 10 ml of methanol. The solid was then allowed to ironic with the vacuum on for about 5 minutes. the dibromo cholesterol melting point was measured and recorded. The ironical solid was weighted and sealed in a vial and stored for next experiment. To debrominate cholesterol, 20 mL of t-butylmethyl ether, 5 mL of acetic acid and 0.2 g of Zn dust were added into the Erlenmeyer flask containing the dibromocholesterol solid. The mixture was swirled for 5-10 minutes in the hood and sonicated in 5 minutes to allow the reaction to go completion. After sonication the solids present were removed by gravity filtration method into a clean 125 mL Erlenmeyer flask. The filtrate was transferred to a 125 mL separatory funnel in which 20 mL of deionized water was added, shaken and allowed to separate into layers. The two layers formed were then separated as water layers and organic (ether) layers. The ether layer was washed with 20 mL of 10% NaOH and then 20 mL of saturated NaCl solution. 100mg of the drying agent magnesium sulfate was added to the organic layer and the solution swirled until dry. The dry ing agent was removed by gravity filtration using a glass funnel fluted filter paper and a very dry 50 mL Erlenmeyer flask. The flask was placed in a warm water bath and then ice cooled for 10 minutes until all but 5 mL of the ether remained following a precipitate formation from the solution. The remaining solvent was decanted and the synthesized cholesterol transferred and allowed to dry in the hood for 20 minutes.The dry solid was weighed and the weight recorded. In addition the melting point was also taken and recorded. To evaluate the effectiveness of the bromination reaction three chemical reactions mentioned above were carried out. NaI in acetone test Five test thermionic tubes labeled A, B, C, D and E were used for this test. About 30 mg of the commercial cholesterol starting cloth was added to tube A 30 mg of dibromocholesterol to tube B 30 mg of the synthesized cholesterol product to tube C 0.3 mL of 1-chlorobutane to tube D and 0.3 mL of t-butyl chloride to tube E. In addition, about 3 mL of acetone was added to each tube to completely dissolve all the compounds. Solutions A-E was used to do the NaI in acetone test as well as the AgNO3 in ethanol test. Tubes A-C did the TLC as well. The NaI in Acetone and AgNO3 in Ethanol tests were performed by saddle horse up a test tube rack containing ten small test tubes. The test tubes were labeled N1 N5 and A1 A5. 1 mL of NaI in acetone reagent was added to test tubes N1 N5, and 1 mL of AgNO3 in ethanol reagent to test tubes A1 A5. This was followed by adding 5-8 drops of A solution to test tube N1 and tube A1, 5-8 drops of solution B to test tube N2 and tube A2, 5-8 drops of solution C to to test tube N3 and tube A3, 5-8 drops of solution C to test tube N4 and tube A4, and 5-8 drops of solution C to test tube N5 and tube A5. The test tubes were heated for a while and all the observations recorded. The sulfuric acid for alkenes test was performed by additional solutions of cholesterol and dibromochol esterol with five dry-cleaned test tubes 1-5. 10 mg of commercial cholesterol was placed in tube 1, 10mg of the dibromocholesterol to tube 2 10 mg of your synthesized cholesterol to tube 3, 10 mg of 2-chlorobutane to tube 4, and 10 mg of cyclohexene to tube 5.About 1 mL of chloroform (CHCl3) was added to each tube and vortex to completely dissolve all solids. In addition, 0.5 mL of H2SO4 was then added to each tube. The observation for this reaction was recorded in the notebook. The TLC analysis of cholesterol and dibromocholesterol was performed by obtaining a silica gel TLC plate and setting it up to run TLC analysis on solutions A-C above. The plate was spotted with each solution and developed by placing the plate using 30% ethyl acetate 70% hexane as the mobile phase. The developed plates were viewed under UV lamp and in the I2 chamber and observations recorded.DiscussionThe yield of the synthesized cholesterol was .29 grams (Table 1). The theoretical yield was 1.08 grams. The a ctual yield was calculated by taking the difference of the weight of the round bottom flask and the synthesized cholesterol by the synthesized cholesterols weight alone. The percent yield was calculated to be 26.9 percent. The synthesize process was not efficient due to the low yield and percent yield of the synthesized cholesterol.The melting point of the synthesized cholesterol and commercial cholesterol seems to fall in the same range. This confirms the purity of the synthesized cholesterol. NaI test showed a positive response as color changed to yellow. The formation of the precipitate also indicated a positive result. The sodium iodide reagent reacted with 1 and 2 alkyl halides through an SN2 mechanism.On the other hand, the silver nitrate reagent reacted with 2o and 3 alkyl halides through an SN1 mechanism. Negative results were observed for both the commercial cholesterol and 1-chlorobutane. Conversely, the t-butyl chloride gave a positive result for the AgNO3test and a negat ive result for the NaI test. The stationary phase of the TLC test was the silica gel TLC plate and the mobile phase was 30% Ethyl Acetate/70% Hexane (Table 6). The distance traveled by commercial cholesterol was 5.5, and for the synthesized cholesterol was 4.6. The difference in the distance traveled and the Rf values of the samples commercial and synthesized cholesterol were pure. Since there were no other spots visible on the TLC plate was a clear indication that there were no contaminations of other chemical compounds present in the sample.

An Analysis of Wilburs Mayflies Essays -- Wilbur Mayflies Essays Poet

An Analysis of Wilburs Mayflies Richard Wilburs recent poem Mayflies reminds us that the American Romantic tradition that Robert hoarfrost most famously brought into the 20th century has made it safely into the 21st. Like many of Frosts short lyric poems, Mayflies describes one persons encounter with an ordinary but good overlooked piece of naturein this case, a cloud of mayflies spotted in a sombre forest(l.1) rising over unseen pools(l.2),made surprisingly attractive and meaningful by the speakers special interrogatory of it. The ultimate attraction of Wilburs mayflies would appear to be the meaning he finds in them. This seems to be an unremittingly positive poem, even as it glimpses the dark subjects of human isolation and mortality, mayhap especially as it glimpses these subjects. In this way the poem may recall that most persistent criticism of Wilburs work, that it is too optimistic, too safe. The poet-critic Randall Jarrell, though an early champ of Wilbur, once wrote th at he obsessively sees, and shows, the bright underside of every dark thing?something Frost was never accused of (Jarrell 332). Yet, when we examine the poem closely, and in particular the series of comparisons by which Wilbur elevates his mayflies into the realm of beauty and truth, the poem concedes something less ?bright? or felicitous to the highest degree what it finally calls its joyful . . . task of poetic perception and representation (l.23). In this poem about seeing from the shadows, the speaker?s revelations are invariably ironic. What could be a more unpromising object of poetic eloquence than mayflies, those leggy, flimsy, short-lived bugs that one ofttimes finds floating in the hulls of rowboats? Yet for Wilbur... ...vocal statement about the ?organic? possibilities of poetry than optimistic readers might have expected. ?Mayflies? forces us to complicate Randall Jarrell?s neat formulation. hither Wilbur has not just seen and shown ?the bright underside of? a ?dark thing.? In a poem where the speaker stands in darkness looking at what ?animates a ragged patch of glow? (l.4), we are left finally in a kind of grayness. We look from darkness into light and entertain an enchanting opinion that we belong over there, in the immortal dance, but we aren?t there now. We are in the machine-shop of poetry. Its own fiat will not let us out completely. Works Cited Jarrell, Randall. ?Fifty Years of American Poetry.? The Third Book of Criticism. NY Farrar, Straus & Giroux, 1969. Wilbur, Richard. ?Mayflies.? Mayflies New Poems and Translations. NY Harcourt Brace, 2000.