Mechanisms of Adsorption of Aormatic Nitrogen Compounds

Mechanisms of Adsorption of Aormatic Nitrogen Compounds MECHANISMS OF ADSORPTION OF AORMATIC NITROGEN COMPOUNDS AND AROMATIC COMPOUNDS ON METAL-ORGANIC FRAMEWORKS (MOFs) by JUN DAI Metal-Organic Frameworks (MOFs) constitute a class of novel porous materials which have attracted significant interest due to their application in separation, storage, catalyst and sensing. Large surface area and porous cavity make MOFs excellent absorbents with huge uptake capacity. In this paper, we studied adsorption mechanisms of adsorption of indole and naphthalene on Basolite F300, Basolite A100 and MIL-100 (Fe) by two complementary spectroscopic methods. Fluorescence spectroscopy and near-UV/Visible diffuse reflectance spectroscopy study demonstrate that naphthalene is quantum confined within the mesoporous cavity in F300. On the other hand, indole is weakly electronically bound to Fe (III) CUS in F300 and forms adsorption complex with F300. Direct spectroscopic proof of adsorption complex is provided by near-UV/Visible spectroscopy and fluorescence spectroscopy. Quenching of ligand-based fluorescence of A100 by indole is suggested and we propose adsorption of indole and napht halene onto A100 via Ï€-Ï€ interaction, spectroscopic proof is provided by fluorescence spectroscopy.   Table of Contents Title Abstract Acknowledgements and Dedication Table of Contents 1 Introduction 1.1 Metal Organic Frameworks (MOFs) 1.2 Clean Fossil Fuels 1.3 Nitrogen Aromatic Compounds in Fossil fuels 1.4 Aromatic Compounds in Fossil Fuels 1.5 Methods of Denitrogenation 1.5.1 Microbial Denitrogenation 1.5.2 Hydrodenigrogenation (HDN) 1.5.3 Adsorptive Denitrogenation (ADN) 1.6 Activation of Open Metal Sites of Metal-Organic Frameworks 1.7 Adsorption of Aromatic Compounds and Aromatic N-heterocyclic Compounds on mesoporous MOFs with CUS: MIL-100 (Fe) and F300 1.8 Adsorption of Aromatic Compounds and Aromatic N-heterocyclic compounds on microporous MOFs without CUS: MIL-53 and A100 1.9 Research Objective 2 Experimental 2.1 Metal Organic Frameworks 2.2 Solvents, Aromatic compounds and N-containing compounds 2.3 Activation and Hydration of Metal-organic frameworks 2.4 Fluorescence Spectroscopy 2.5 Near UV-Vis Diffuse Reflectance Spectroscopy (near UV-Vis DRS) 2.6 Model Fuels 2.7 Solid Mixture of Aromatic and Aromatic N-hetrocyclic compounds with MOFs 2.8 Stoichiometric adsorption complex of F300 and naphthalene in eicosane matrix 2.9 Kinetic adsorption of liquid indole on Basolite F300 (FeBTC) in liquid phase 2.10 Stoichiometric adsorption complexes of indole/naphthalene with MOFs 2.11 UV radiation 3 Results 3.1 Spectroscopic Studies of adsorption of naphthalene and indole on mesoporous F300 and MIL-100 (Fe) with CUS 3.1.1 Solid Mixtures of MOFs and organic aromatic compounds 3.1.2 Fluorescence spectrum of pure naphthalene List of Figures Figure 1: Structure of MIL-100 (Fe) (see as S1 in supplementary) Figure 2: Structure of MIL-53 (Al) (see as S2 in supplementary) Figure 3: Common nitrogen compounds existing in fossil fuels Figure 4: Pathways for the transformation of quinoline Figure 5: Fluorescence spectrum of (A) 0.08 M liquid solution of naphthalene (NAP) in n-heptane, ÃŽ »exc = 280 nm, bandwidth: Exc. Slit 5 nm/Emi. Slit 5nm. (B) 0.08 M liquid solution of NAP in n-heptane with multi-Gaussian curve fitting Figure 6: Fluorescence spectrum of (A) pure naphthalene (NAP) ÃŽ »exc = 280 nm, bandwidth: Exc. Slit 5 nm/Emi. Slit 5nm (B) pure NAP with multi-Gaussian curve fitting List of Tables Table 1: MOFs used in this research and structure information Table 2: Physical property of common nitrogen aromatic compounds existing in fossil fuels 1 Introduction 1.1 Metal Organic Frameworks (MOFs) Porous materials are well studied and widely used in science and engineering industry. Recently, a novel kind of porous material ‘Metal-Organic Frameworks (MOFs)’ has emerged as potential competitor. MOFs are crystalline hybrid inorganic-organic porous solid formed by chemical metal-linker bounding1. Metal-Organic Frameworks (MOFs) constitute a class of novel porous materials which have attracted significant interest due to their application in separation, storage, catalyst and sensing. The use of MOF as stationary phase in high resolution GC separation of aromatic hydrocarbons has also gained significant attention2. In comparison with adsorption on the MOFs in gas phase which has been well studied and understood, adsorption on the MOFs in liquid phase is much less known. MOFs have extremely large surface area and porous cavity, which make them excellent adsorbents with huge uptake capacity. As a class of coordination compound repeated by metal or metal clusters as SBUs (second building units) and organic linkers, the cavity ranged between that of Zeolite and mesoporous silica3. Regarding the structures, variety of MOFs can display either 2 dimensional or 3 dimensional structures depend on different organic linkers. It is also indicated by J. R. Karra and K. S. Walton that the relation between pore size and guest molecule size plays an essential role in the adsorption4. The MOFs being investigated in this research are mesoporous and microporous MOFs. For mesoporous MOFs the pore size can vary from 2 nm to 50 nm, while for microporous MOFs the pore size is less than 2nm. Pore size can be a key in adsorption on MOFs due to micropore filling mechanism2, which suggests adsorption capacity depends on molecular cross-sectional area rather than minimum diameter. MOFs are structurally stable under ambient environment. It is reported by many authors that MOFs remain stable under increased temperature and under oxygen. In this research, our investigation mos tly focuses on several common MOFS, and their commercial names are Basolite C300, Basolite F300, Basolite A100 and MIL-100 (Fe) (MIL=Materials of Institute Lavoisier). All Basolite C300, Basolite F300 and Basolite A100 are bought commercially, and MIL-100 (Fe) is made with the collaboration of Dr. Jing Li from Rutgers – New Brunswick. Table 1 shows the basic physical information of the MOFs used in this research. Table 1: MOFs used in this research and structure information MOFs/formula Surface area/m2g-1 Pore dimension/Ã… Pore dimension Ref. BET Basolite F300 1300~1600 21.7 3D Sigma-Aldrich,5 Basolite A100 1100~1500 7.37.7 1D Sigma-Aldrich, MIL-100 (Fe) 2200 25, 29 3D 5 MIL-100 family MIL-100(M) (M=Cr, Fe, Al) refers to a family of mesoporous Metal-Organic Frameworks built up from metal clusters and benzene-1, 3, 5-tricarboxylic (BTC) linkers. These MOFs possess large surface area and have recently attracted tremendous attention for applications in adsorption and separation due to the coordinated unsaturated sites (CUS) which can provide chance for Lewis acid-base interaction between guest molecules and metal ions or metal clusters. In Metal-organic frameworks, metal sites (SBUs) are coordinated with organic linkers. Open metal sites (CUS) may be available on these SBUs. CUS are very important in gas storage, separation, sensing, catalysts, and even biological systems6. Considerable amount of research on the adsorption of small molecules have been done recently. Evidence has shown open metal sites have essential influence on adsorption property in MOFs. It is reported that open Cu2+ metal sites in HKUST-1 contribute significantly to the high acetylene storage capa city7. Moreover, MOFs with CUS such as HKUST-1 are used in chromatography separation due to its specific feature to distinguish strongly and weakly electron donating analytes8. In additional, MIL-100 (Fe3+, Cr3+, Al3+) has been shown to have strong preference to adsorb N-heterocyclic compounds (Lewis base) in mixtures910. Hence, open metal sites can be potential Lewis acid sites, the possible interactions between guest molecules and open metal sites will be examined and discussed in this paper. In our research, MIL-100 (Fe) will be used to investigate the adsorption mechanisms between guest molecules such as indole or naphthalene and sorbent MOFs. Besides MIL-100, there is a commercially made MOF named Basolite F300, which has a similar chemical composition. Both Basolite F300 and MIL-100 (Fe) are built up by Iron and BTC linkers. However, due to the poor crystallinity, the actual structure of F300 is still not known at this time. Difference in iron content and carbon content in F300 and MIL-100 (Fe) is shown by D. Amarajothi and his co-workers5. The iron mass content in F300 and MIL-100 (Fe) are respectively 25% and 21%. The carbon mass content in F300 and MIL-100 (Fe) are respectively 32% and 29%. Pore dimension in F300 and MIL-100 (Fe) are respectively 21.7 Ã… and 25/29 Ã…. Structure of MIL-100 (Fe) is shown below: Figure 1: Structure of MIL-100 (Fe) (see as S1 in supplementary) MIL-53 family There are many types of MOFs that undergo hydrolysis, while there are other MOFs that remain stable within water. Water stable MOFs start to showing potential applications in drug delivery and imaging11. Many MOFs containing Al as metal sites and amino acids as organic linkers are stable in aqueous solution, and it is also possible to synthesize them in aqueous environment12. MIL-53(M) (M= metal as Al13, Cr14, Fe15, In16, Sc17) is a common family of microporous MOFs and has excellent water stability. Figure 2: Structure of MIL-53 (Al) (see as S2 in supplementary) The one dimensional pore structure of MIL-53(Al) is built by chains of corner-sharing octahedra aluminum clusters AlO4(OH)2 and anion form of benzene-1,4-dicarboxylic acid (BDC) as organic linkers connecting infinite numbers of metal clusters. MIL-53 (Al) has rhombic channels which have dimension of 7.3 x 7.7 Ã…. A huge Langmuir surface area of 1600 m2/g makes MIL-53 (Al) an efficient adsorbent. MIL-53 (Al) has extraordinary thermal stability up to 773 K. It is believed that the structure of MIL-53 (Al) undergoes a reversible structural change during process of adsorbing/desorbing water molecules, and is described as ‘breathing’13. The so-called ‘breathing’ process interchanges between large-pore (lp) form (Al(OH)[O2C-C6H4-CO2]) and narrow-pore (np) form (Al(OH)[O2C-C6H4-CO2]H2O) 13. The lp form has a dimension of 8.5 x 8.5 Ã… and is obtained when activated upon high temperature and under high vacuum, which takes away excess free BDC acids, oxygen and water trapped in the cavity during synthesis. The lp form is capable of adsorbing water molecules in vapor at room temperature, as a result, the MIL-53 (Al) shifts to its’ np form. As shown in the formula, the np form contains one trapped water molecule every unit or cavity. Hydrogen bonds are found to form between carboxylic groups on the linkers and adsorbed water molecules. Due to this ‘breathing’ feature, applications on selective adsorption of various compounds in gas phase have already gained interest and being reported14. The np form of hydrated MIL-53 (Cr) is able to selectively adsorb CO2 in presence of CH4 in gas phase. Upon adsorption of CO2 but not CH4, MIL-53 (Cr) returns to its lp form with an increased cavity volume of 1522.5 Ã…3 from np volume of 1012.8 Ã…3. In our research, we used Basolite A100 MOF from the BASF, which is commercially available and is equivalent to MIL-53 (Al). Similarly, A100 is build up with AlO4(OH)2 octahedral clusters connecting by BDC linkers, and gives a surface area of 1084 m2/g and pore volume of 0.51 cm3/g as determined by N2 physical-adsorption at 77 K. Additionally, XRD pattern of A100 is proved to resemble that of MIL-53 (Al)18. G. Blanco-Brieva and his co-workers have studied adsorptive removal of aromatic sulfur compounds from model liquid fuels on thermally activated A10019. 1.2 Clean Fossil Fuels Combustion of sulfur and nitrogen containing compounds in fossil fuels will bring adverse effect to public health, environment and economy. It is widely recognized that nitrogen compounds are normally carcinogenic and mutagenic. Separation of heterocyclic compounds from petro-chemical feedstock has become an urgent application leading to clean liquid fossil fuels. Fossil fuel is a primary source of energy on the earth, the intensive use of fossil fuels has raised environmental concerns. Beginning in 2006, the Environmental Protection Agency (EPA) began an ambitious program aiming to reduce the sulfur content of diesel fuels. As of July 11, 2010, the EPA required that the concentration of sulfur content in diesel fuels not exceed 15 ppm20. For certain ultra-clean gasoline, diesel fuels and jet fuels, sulfur level needs to be lower than 1 ppm21. Hydrodesulfurization (HDS) of diesel fuel has become an essential research interest, while the presence of nitrogen compounds in middle-distil late oil inhibits the ultra-deep hydrodesulfurization22232425. In HDS, sulfur compounds are hydrogenated to hydrocarbons and H2S over catalyst such as Zeolites9. However, the nitrogen aromatic compounds in crude oil are found to compete for the active sites on these catalysts to inhibit a deep HDS26,27. This gives rise to the necessity for denitrogenation in fossil fuels. Moreover, the combustion of nitrogen compounds in petroleum leads to the formation of NOx oxides, which is a group of highly reactive and persistent species and contributes directly to acid rain and greenhouse effect. The life time of NOx oxides in atmosphere is 120 years before being removed or destroyed through chemical reactions. The impact of 1 pound of NO ­x on warming the atmosphere is over 300 times that of 1 pound of carbon dioxide. EPA first set standards for NO2 in 1971, setting both a primary standard (to protect health) and a secondary standard (to protect the public welfare) at 0.053 parts per million (53 ppb), averaged annually28. Also the presence of nitrogen aromatic compounds in fossil fuels can lead to poisoning of refining catalyst, which will eventually cause a decrease in yield. Thus, denitrogenation is necessary for deep desulfurization and has drawn significant interest around the world due to the increasingly rigid regulations and fuel specifications in many countries. 1.3 Nitrogen Aromatic Compounds in Fossil fuels Fossil fuels are naturally-formed fuel that contains significant level of heterocyclic aromatic contaminants. There are some representative sulfur aromatic compounds such as benzothiophene (BT) and dibenzothiophene (DBT), representative nitrogen aromatic compounds such as indole and quinoline. Nitrogen aromatic compounds content in crude oil averages around 0.3%. Although the concentration of nitrogen compounds in crude oil is relatively low, the concentration turns out to be higher throughout the petroleum distillation process. Common nitrogen aromatic compounds in fossil fuels are shown in Figure 1.129 and physical properties of nitrogen aromatic compounds investigated in this research is shown in Table 2. Nitrogen aromatic compounds in fossil fuels fall into two classes. One is non-basic nitrogen compounds including indole and pyrrole due to the fact that the extra pair of electrons on N is contributed to the Ï€ electron cloud and is not available for interaction with acids. While the other class is basic nitrogen compounds such as pyridine, quinoline and their derivatives, in which the lone pair of electrons on N is available as an electron donor. Indole is one of the most common nitrogen compounds in fossil fuels, and it has been broadly studied. And we choose indole in our research due to the fact that indole is a weakly basic N-containing compound, which means it has a potential of selective adsorption against aromatic compounds and desorption is possible and reasonably convenient. Figure 3: Common nitrogen compounds existing in fossil fuels Table 2: Physical property of common nitrogen aromatic compounds existing in fossil fuels Compounds Formula Melting Point, ÃÅ'Ã…  C Density, g/cm3 Dipole moment, D Acidity,pKa Maximum diameter, ÃÅ'Ã…  A Indole C8H7N 52~54 1.17 2.11 16.2 6.9 Quinoline C9H7N -15 1.093 0 4.85 7.2 Isoquinoline C9H7N 26~28 1.099 0 5.14 7.2 1.4 Aromatic Compounds in Fossil Fuels Fossil fuels contain significant amount of hydrocarbons, most of them are aromatic compounds and polycyclic aromatic hydrocarbons (PAHs). In this research we choose naphthalene as representative aromatic compounds, and in order to investigate the adsorption mechanism we use fluorescence spectroscopy and UV-Vis diffuse reflectance spectroscopy to investigate electronic interactions upon adsorption onto MOFs. Naphthalene is the most simple and common aromatic compounds in PAHs. And naphthalene is commonly produced in petroleum refining and is then separated from the petroleum. Purification and separation of these aromatic rings is of interest in chemical industry. Naphthalene has a molecular length of 7.2 Ã… (largest diameter determined by ChemDraw 3D) and is non-polar. 1.5 Methods of Denitrogenation Microbial Denitrogenation Microbial process is an alternative pathway for denitrogenation. Microorganisms are known to consume natural organic compounds and convert them into carbons and energy, and they are capable of metabolizing certain molecules including nitrogen compounds from fossil fuels. The degradation of quinoline is well-characterized, and the transformation pathways are elucidated by M. Benedik et al29 (shown in Figure 1. 5). The degradation of isoquinoline is less understood but 1-oxo-1,2-dihydroisoquinoline is suggested as initial oxygenated product30. According to the finding of Claus, G, indole is readily degraded via catechol or transformed directly into tryptophan30, while carbazole is relatively more difficult to be degraded. One possible degradation pathway31 beginning with angular dioxygenation has been proposed by Ouchiyama, N., which finally enters TCA cycle after conversion to catechol or tryptophan32. Mechanisms for the degradation of other nitrogen compounds such as pyridine, quinol ine, acridine and their derivatives are reviewed in detail by J. Kaiser33. Recent research in microbial denitrogenation has revealed a promising future for application in selective removal of nitrogen- and sulfur-containing petroleum. However, as a major mechanism for the removal and metabolism of organic compounds from the environment, its’ characterization of the enzymes involving in the pathways is still under research29. And it has not been widely applied to the industry yet. Figure 4: Pathways for the transformation of quinoline Hydrodenigrogenation (HDN) Hydrodenitrogenation (HDN) is usually used to remove nitrogen compounds in fossil fuels during the refinery process, and Co-Mo catalyst is normally involved in the process. However, the HDS process is accomplished by reacting with hydrogen at high temperature and high pressure. It is energy-intensive, hazardous and costly. Thus, significant amount of researches have been done on HDN in order to reach a goal of being economic and environmentally friendly. Adsorptive Denitrogenation (ADN) Another promising way to selectively remove the nitrogen compounds in fossil fuels is adsorption on a porous material, Activated carbon34353637, Zeolites38, HCL-loaded silica-aluminas39, ion-exchange resins40, meso-silicas41,42, Ti-HMSs43, microporous carbon44, activated aluminas45, Ni-based adsorbents45, and NiMOs46 have been used for ADN. While recently the use of MOF adsorbents has gained significant interest in adsorption and separation of aromatic and heterocyclic compounds in liquid phase due to its’ high capacity, high selectivity, economic importance and most importantly energy saving 47. Moreover, MOFs can even be recycled and effectively reduce the cost. Adsorptive separation via â€Å"adsorptive denitrogenation (AND)† is preferred over industrial catalytic HDN10. Specifically, selective adsorption of N-heterocyclic compounds48 in presence of aromatic and aliphatic hydrocarbons in liquid phase49 is of interest, which is investigated in this research. 1.6 Activation of Open Metal Sites of Metal-Organic Frameworks Available CUS in MOFs is essential for the adsorption of Lewis basic compounds. Thus, to fully utilize the open metal sites in MOFs, activation is needed to evacuate the water molecules which are relatively weakly coordinated on these metals. Because MOFs are strongly adsorptive molecules, humidity can be crucial to the availability of open metal sites in MOFs. Specific treatment is necessary at certain temperature under vacuum in order to activate open metal sites. And protection of the sample against humidity is critical during experiments. Interestingly, it is discovered by K. Schlichte and his colleagues that upon activation the color of HKUST-1 would change from light cyan to dark navy50. This is confirmed by E. Borfecchia and his working group using UV-Vis, a red shift at LMCT edge and appearance of a shoulder in d-d band at around 600 nm in UV-Vis spectrum is observed and explained by the removal of water51. In addition to the activation of MOFs, partial reduction of MIL-100 (Fe) has been reported by H. Leclerc and his group52. Certain metal sites in MOF can be reduced, for example, Fe3+ in MIL-100 (Fe) can be reduced to Fe2+. According to their analysis of oxidation states via IR, outgassing at 423 K for 12 hour will give rise to a greater proportion of Fe2+ sites while minority of Fe3+ sites is reduced. However, outgassing at 523 K will result in that most Fe3+ sites are reduced. Fe3+ sites are more Lewis acidic sites than Fe2+, it is easier for Fe3+ to form coordination bond with nitrogen aromatics, which are good Lewis base. 1.7 Adsorption of Aromatic Compounds and Aromatic N-heterocyclic Compounds on mesoporous MOFs with CUS: MIL-100 (Fe) and F300 Although adsorption of small organic molecules on MOFs both in liquid phase and in vapor, such as toluene, benzene, xylene isomers2, etc., has been well studied in the recent years, to our knowledge the adsorption of fuse-ring aromatic hydrocarbons on MIL-100 in liquid phase has not been reported. M. Maes and his co-workers have reported adsorption of indole from heptane/toluene mixture solution on MIL-100 family9. Thus, mechanism of adsorption of aromatic compounds versus aromatic N-heterocyclic compounds on F300 has not been studied. According to many studies, the formation of complexes in liquid adsorption is usually assumed, but there is a lack of direct spectroscopic evidence. Adsorption of small aromatic ring compounds (benzene and p-xylene molecules) on MIL-101 has been published by K. Yang, et al2. Pore-size filling mechanism is discovered and discussed in this paper, indicating that pore-size and different substrate relates with molecular selectivity of organic compounds. Ho wever, the mechanism is still not understood. Fluorescence spectroscopy is a straightforward method for studying the adsorption mechanism between guest molecules and MOFs. Yet there are rarely papers studying characterization of adsorption of aromatic compounds in liquid or solid system by fluorescence spectroscopy. It is assumed based on fluorescence spectra that Lewis acid-base interaction promotes the adsorption of pyrene on Al2O3 from model fuel using octane as solvent53. While the fluorescence spectra was collected using a model sorbent aluminum chloride in methanol instead of actual Al2O3 in model fuel, spectroscopic characterization of adsorption complexes formed by MOFs and aromatic compounds or aromatic N-heterocyclic compounds by the fluorescence spectroscopy is still unknown to our knowledge. Another useful characterization method is near-UV/visible diffuse reflectance spectroscopy (DRS), which is excellent at detecting the variation or shift in electronic states on adsorption complexes forming by metal sites and guest molecules. The DRS was used to identify the interactions between aromatic amines and MOFs54 but it has not been used to explore the interactions between metal sites of MOFs and guest molecules as aromatic compounds or aromatic N-heterocyclic compounds. Thus, we aim to investigate the adsorption of large aromatic compounds on MOFs using two spectroscopic methods as fluorescence spectroscopy and near-UV/visible diffuse reflectance spectroscopy. 1.8 Adsorption of Aromatic Compounds and Aromatic N-heterocyclic compounds on microporous MOFs without CUS: MIL-53 and A100 M. Maes and his colleagues have studied the adsorption of indole and methyl-substituted indole present in model fuel (heptane/toluene at either 80 vol. %/20 vol. % or 20 vol. %/80 vol. % combination) at initial concentration of 0.15 M on thermally activated MIL-53 (Al)9. The amount of absorbed indole intensively dropped in model fuel with toluene, which indicates a possible competitive adsorption. While no data of adsorption capacity for indole and substituted indole on MIL-53 (Al) in n-alkane solvent was reported, not enough experimental evidence or computational evidence can be used to prove the mechanism of competitive adsorption. Similarly, adsorption of indole, pyridine, pyrrole and quinolone on thermally activated MIL-53 (Al) has been studied in another paper. In this paper n-octane was used as solvent, however, no data for adsorption capacity of indole on MIL-53 (Al) has been reported55. Ï€-Ï€ interactions is suggested to be the major force that introduce the adsorption of indole or quinolone onto activated MIL-53 (Al), but no experimental evidence was given55. At the present time, no direct spectroscopic characterization of chemical bonds between aromatic or hetero-aromatic adsorbate and MIL-53 has yet been reported. Furthermore, adsorption of naphthalene on MOFs has not been reported to our knowledge. To investigate the adsorption mechanisms through fluorescence spectroscopy, it is essential to know the origin of the fluorescence from MOF itselft. It was discussed in a review paper by M. Allendorf, C. Bauer, R. Bhakta et al.56, that there are five modes for generating fluorescence in MOFs: linker-based, framework metal ions (charge transfer between linker and metal), adsorb

Caribbean Literature Essay

The evolution of Caribbean Literature started centuries before the Europeans graced these shores and continues to develop today. Quite noticeably, it developed in a manner which transcended all language barriers and cultures. Today the languages of the Caribbean are rooted in that of the colonial powers – France, Britain, Spain and Holland – whose historical encounters are quite evident throughout the region. The cosmopolitan nature of the region’s language and cultural diversity develop from the mixture of European languages with Native American languages (mainly the Caribs and Arawaks) in the formation of creoles and local patois (hybrid languages) and those of Africans brought to the Caribbean as slaves, not withstanding the contributions of Asians mainly from India and China, and Middle Easterners. The fabric of Caribbean Literature is woven with the historical issues of enslavement and forced migration, the related themes of home and exile, and colonialism and decolonization. The social and cultural themes of tradition, landscape, culture and community are also encompassed by Caribbean Literature. It also addresses such universal questions as identity, sexuality, family life, pain, joy, and the uses of the imagination. It is virtually impossible to keep Caribbean Literature only within the confines of writings produced within the Caribbean Islands. Caribbean Literature also transcends the borders of Central and South America extending to the shores of Guyana, Suriname, French Guiana; and coastal areas of Colombia, Nicaragua, Belize and Honduras. Evidence of aspects of Caribbean Literature can also be seen in literary works produced in various areas of the USA including Miami and New Orleans. Works of Caribbean Literature have also been produced by people of Caribbean ancestry who live primarily in Europe and major urban centers of the United States. ORAL LITERATURE Oral literature can be considered as the earliest form of Caribbean Literature consisting mainly of rich folk- tale traditions, legends and  myths, songs and poetry. Today this legacy is resplendent in popular music such as the CALYPSO, the Cuban SON, and the Puerto Rican BOMBA; in the traditions of storytelling originating out of West Africa and India; and in supernatural tales from African religions, including SANTERIA, LUCUMI,VODUN (vodoo), and SHANGO. Proverbs, riddles, and sayings that reinterpret African, European, and East Indian traditions are also most prominent in Caribbean literature. Among these are Anancy (a cunning spider) stories; animal dilema tales, which typically teach a moral lesson; stories of village life or evil women; tall tales; and rhetorical flourishes, such as boasting, toasts, and speeches. PRE AND POST INDEPENDENCE LITERARY WORKS Autobiography and poetry were the most prevalent literary works from the 16th century to the mid – 19th century. In these works were introduced themes that became common in Caribbean literature; exile, migration, displacement and questions of identity. The history of Mary Prince, a West Indian Slave, (Related by Herself), is the most prominent of these writings in English. Early Caribbean writings in Spanish saw that of the autobiography of the slave Juan Francisco Manzano of Cuba in the 1820’s and 1830’s, Jose Maria Herida Placido ( a slave who was executed in1844 for his role in a slave uprising) and the Cuban anthropologist Miguel Barnet. Max Urena of the Dominican Republic produced nationalist works in the 19th century. The French speaking Caribbean saw works by Emeric Bergeaud and Desmevar Delorme. Distinct national literary traditions began in the 20thcentury because few Caribbean countries gained their independence before this period. Twentieth century Caribbean literature can be divided into three periods: the first thirty years during colonial rule; the years just prior to independence between the 1940’s and 1960’s or later, and the period after independence. During the fledgling years (1930’s) a movement celebrating African culture and values rose to prominence. The movement originated in France and was called NEGRITUDE. However, its founders include Leon Gontran Damas of French Guiana and Aime Cesaire of Martinique. Rene Maran of Martinique won the Prix Goncourt (a French literary prize) with the novel Batouala (1921) which called for identification with black culture. In the Spanish – speaking Caribbean African themes were presented in a most exotic manner, highlighting African and black identity for artistic inspiration. Prominent writers in this movement include Luis Pales Matos from Puerto Rico and Emillo Ballagas from Cuba. The works of Cuban poet Nicolas Guillen from the 1930’s share sentiments with the politics of NEGRITUDE and address issues surrounding the struggle against colonialism. Alejo Carpentier, also of Cuba, achieved recognition with his novels in which he explores the history and sources of Caribbean culture. The English – speaking Caribbean abounds with prominent writers including Jamaican novelist Tom Redcam (Thomas Macdermot), Claude Mckay, Jamaican born poet, and perhaps the best known writer of this generation internationally. Mckay later became one of the leading writers of Harlem Renaissance, a flowering black culture in New York in the 1920’s and 1930’s. Other writers who rose to prominence during this period are C. L. R. James of Trinidad, whose works protest against colonialism and help to define the anticolonial political and cultural struggles of his time. He was also instrumental in the formation of the literary magazines Trinidad (founded 1929) and the Beacon founded (1931); these publications were instrumental in the development of a Caribbean literary tradition. Alfred Mendes and Ralph de Boissiere (Trinidadians) both contributed articles and poetry to the magazines. PRE – INDEPENDENCE RENAISSANCE This period saw the emergence of a generation of writers whose works sought after liberation and presented a distinctive portrait of Caribbean culture. The Jamaican Vic Reid, looks forward to a â€Å"new day† of independence with his novel New Day (1949); the displaced, downtrodden, urban population of the Caribbean is portrayed by Roger Mais also of Jamaica. He also experiments with jazz rhythms in his language, while Una Mason, a Jamaican poet uses blues rhythm in her poetry collections. A vivid portrait of Guyana’s countryside and society is presented by Edgar Mittleholzer in his novel A Morning At The Office (1950). On the other hand, one of the first and most important Caribbean works dealing with childhood and coming of age in a colonial context was produced by George Lamming, from Barbados, in the novel â€Å"In The Castle Of My Skin† (1953). This novel focuses on the struggles of three young boys with poverty, a colonial education, social change and the forging of an identity; hovering in the background is the promise of migration to the metropolitan centers. The mythology of Native Americans and Africans is emphasized in Wilson Harris’s novel Palace of the Peacock (1960), while Martin Carter’s Poems of Resistance seek liberation from colonial rule. During this period a number of female writers were also very active. Beryl Gilroy of Guyana wrote novels, children’s stories, and an autobiography. Sylvia Wynter of Jamaica incorporates elements of folk culture into her work. From Dominica, Phyllis Shand Allfrey won recognition for her analysis of colonial power in her work, while Jean Rhys received critical acclaim for novels about women caught in situations they are unable to change. POST INDEPENDENCE This period saw the emergence of poets from the English – speaking Caribbean; Derek Walcott from Saint Lucia is perhaps the best-known Caribbean writer internationally. In 1992 he won the Nobel Prize for literature. In addition to poetry, Walcott is well known as a playwright. At the same time Eduard Kamau Brathwaite challenged the formal structures of European poetry by adopting the rhythms, references, and language of the African and Afro- Caribbean traditions. Brathwaite broadened the possible use of language in his works for a number of subsequent writers, including Jamaican oral poets Mutabaruka, Linton Quesi Johnson, and John Binta Breeze. Earl Lovelace and V. S. Naipaul count among other noted English – language writers born in Trinidad and Tobago. Naipaul received recognition for novels that focus on East Indians living in the Caribbean. Lovelace whose works won a Commonwealth prize wrote on issues of poverty, education, and village life. The French – speaking Caribbean saw prominent contemporary writers in Daniel Maxim of Guadeloupe and Edouard Glissant and Patrick Chamoiseau of Martinique. Chamoiseau explores issues of black identity, and creole cultural identity. The latter was produced along with Jean Bernabe and Rafael Confiant. Chamoiseau won the Pri Goncourt for his novel Texaco (1929). Noted female writers are Maryse Conde of Guadeloupe who is considered a significant voice among female writers, having won several French prizes for her literary work. Simone Schwarz -Bart, also of Guadeloupe, writes of the search for identity while Nancy Morejon of Cuba is recognized as a leading poetic voice. Her collection entitled Cuaderno de Granada 1984 (Grenada Notebook, 1984) honors those who participated in Grenada’s socialist revolution in 1983. Caribbean writers have impacted greatly on the international arena and have gained worldwide recognition for their numerous works. Literary critics are also recognizing the Caribbean roots of some African American writers who are explicit about their Caribbean parentage

Complementary and Alternative Medicine

The number of Complementary and Alterative medicine (CAM) consumer is constantly increasing. According to the National Health Information survey in 2004, nearly 40% of American adults used some form of alternative therapies and spend around 30 billion dollars per year on unconventional medicine (Kayne 2008, p. 93). The term â€Å"alternative medicine† refers to all the therapeutic practice that is not part of the conventional medicine such as: herbal medicine, acupuncture and yoga (Hirsch, 2009).Allopathic medicine is based on scientific knowledge that has already been proven efficient whereas most of homeopathic treatments are based on tradition and beliefs in spiritual energies. It will be argued that although logical issues and concerns dealing with the unconventional therapy, the various advantages of homeopathic methods outweigh any potential inconveniences if it is well practiced and complementary.This is essay will examine the various drawbacks and benefits of this ther apeutical approach. First of all, on the disadvantage side alternative medicine usually does not heal the patient instantly. Indeed herbal treatments for instance can take weeks before a real improvement appeared. Sometimes numerous acupuncture sessions or massages are required for a long lasting result. As a consequence the one concerned can get impatient and decided to switch to a more conventional healing.Moreover, according to Dr. Hirsch (2009) to adopt CAM it demands to invest a considerable amount of time, energy and money (as it is rarely covered by health insurance). Furthermore, doctor denounces the fact that some people choose to treat some severe disease primarily with alternative therapies whereas it should only be in addition to conventional medicine. Under those circumstances, damage can be done beyond repair by the time the patient realize that the treatment do not work at all.Besides, CAM practices can meddle with conventional medication, for example herbal supplemen ts can interfere with treatments like birth-control pills. Above all, Dr. Hirsch (2009) states that CAM users must keep in mind that contrary to conventional medical doctors, there is only few trained and licensed CAM practitioners. As an illustration, practice such as yoga can be dangerous if the movement are not done properly with a professional. Finally few scientists like Kaptchuk. (2002) note that placebo effect may enhance results from alternative remedy.As the CAM users believe for instance, that healing ritual such as acupuncture is good for their mind and body it will then have true benefits on the patients for some specific illness as emotional state can influence the immune system. Although this may be true that CAM practice must be done with carefulness and awareness it is not true that the demerits brought by CAM prevail over the merits. First thing to remember in the advantage side, as stated by Buzescu (2011, p. 130) alternative therapies have almost no side effects a s it works with the body instead of eliminating symptoms like the conventional medicine.The scientist also holds the views that it is a green friendly practice; natural substances are applied and the modus operandi is quiet simple. In the same way this searcher believes that users may feel reassured that they will probably not found dangerous and polluted chemicals in their products. In addition, it is important to realize that millions of underprivileged families heal themselves and rely only on unconventional medicine thanks to the fact that it not expensive, contrarily to the modern drugs.Moreover the complementary healing approach is becoming increasingly successful for its aptitude to diagnosticate and focus on the real nature of the disease. It pays more attention to the mental and emotional symptoms. As a matter of fact practitioners have the knowledge and are engaged to encourage the mind-body connection. Consequently they give to others the aptitude to bear their sickness t hrough various resources, techniques and natural remedies. Buzescu (2011, p. 30) goes on to say that the main goal of complementary medicine is to â€Å"help or complete classical treatment methods†. In other words CAM is used in addition to conventional healing treatments, to deal with symptoms or side effects that had not been yet cured. In this case, it has been suggested to patients to discuss with the conventional doctor about their intentions to add complementary healing techniques to their previous treatment and more especially if it involves herbal therapies Malbley(1998).Likewise, this practice is becoming more accepted and approved by the conventional doctors, but keep in mind that it can only works as a complement and not as an alternative, a complement should not lead to a total replacement Dawson (2008). Indeed there is finally a theory that CAM treatment can be use for disease like cancer, as it procures some reliefs from signs and symptoms (Tovey, Chatwin and B room, 2007). To conclude, in recent years CAM healing approach have risen in popularity among industrialized countries.One the one hand, it shows some disadvantages as it may be a long-term treatment that demand a lot of personal investment and which is sometimes taken without a full knowledge of the facts that it may only rely on the placebo effect. On the other hand it merits such as the fact that there is no side effect, it is a cost effective and green approach that focus on the core of the disease to heal, largely compensate the demerits if it is used as a complement. However it is obvious that in order to avoid any abuse, governments should implement laws and regulations toward CAM practice.

Standards For Accounting and Review Services - Free Essay Example

Sample details Pages: 8 Words: 2375 Downloads: 7 Date added: 2017/09/21 Category Finance Essay Type Review Did you like this example? r Answer D is correct because the SSARS requirements do not apply to either the processing of financial data for clients of other CPA firms or to consulting on accounting matters. See AR 100 for these and additional services to which the SSARS do not apply. 54. Statements on Standards for Accounting and Review Services establish standards and procedures for which of the following engagements? a) Assisting in adjusting the books of account for a partnership. b) Reviewing interim financial data required to be filed with the SEC. ) Processing financial data for clients of other accounting firms. d) Compiling an individual’s personal financial statement to be used to obtain a mortgage. Answer D is correct. The SSARS apply when a CPA either compiles or reviews the financial statements of a nonpublic entity. 55. Blue Co. , a privately held entity, asked its tax accountant, Cook, a CPA in public practice, to reproduce Blue’s internally prepared interim financial statem ents on Cook’s microcomputer when Cook prepared Blue’s quarterly tax return. Cook should not submit these financial statements to Blue unless, as a minimum, Cook complies with the provisions of a) Statements on responsibilities in Tax Practice. b) Statements on Standards for Accounting and Review Services. c) Statements on Responsibilities in Unaudited Financial Services. d) Statements on Standards for Attestation Engagements. Answer B is correct because Statements on Standards for Accounting and Review Services apply (AR 100) and require that the CPA who wishes to submit such financial statements to a client must, at a minimum, meet the compilation requirements. 56. A CPA should not submit unaudited financial statements of a nonpublic company to a client or others unless, as a minimum, the CPA complies with the provisions applicable to a) Compilation engagements. b) Review engagements. c) Statements on auditing standards. d) Attestation standards. Answer A is co rrect. An accountant should not submit such information unless he has, at a minimum, complied with the provisions applicable to a compilation engagement. . 57. An accountant who is not independent of a client is precluded from issuing a a) Compilation report on historical financial statements. ) Compilation report on prospective financial statements. c) Special report on compliance with contractual agreements. d) Report on consulting services. Answer C is correct because providing special reports is an attestation service and therefore requires the accountant to be independent. 58. Which of the following replies does not include a portion of the â€Å"Special Committee on Assurance Services† definition of assurance services? a) A consulting service. b) Improve the quality of information. c) Improve the context of information. d) For decision makers. Answer A is correct because the Special Committee on Assurance Services, also referred to as the Elliott Committee, defined a ssurance services as independent professional services -not a consulting service-that improve the quality of information, or its context, for decision makers. 59. In connection with the element of inspection, a CPA firm’s system of quality control should ordinarily provide for the maintenance of a) A file of minutes of staff meetings. b) Undated personnel files. c) Documentation to demonstrate compliance with its policies and procedures. ) Documentation to demonstrate compliance with peer review directives. Answer C is correct. The requirement is to determine what inspection, an element of quality control, should include. Answer C is the most accurate because it provides for maintenance of documentation of the various quality control policies and procedures. Thus, it is all encompassing. Answers A, B, and D, while desirable, relate to more specific areas and are thus less complete than C. 60. Which of the following is not an element of quality control for a CPA firm? a) Indep endence, integrity and objectivity. ) Acceptance and continuance of clients and engagements. c) Engagement supervision. d) Monitoring. Answer C is correct. Engagement supervision is not an element of quality control. The five elements of quality control are (1) independence, integrity, and objectivity, (2) personnel management, (3) acceptance and continuance of clients and engagements, (4) engagement performance, and (5) monitoring. 61. As guidance for measuring the quality of the performance of an auditor, the auditor should refer to a) Statements of the Financial Accounting Standards Board. ) Generally accepted auditing standards. c) Interpretations of the Statements on Auditing Standards. d) Statements on Quality Control Standards. Answer B is correct because auditors are responsible for compliance with generally accepted auditing standards and comparison of their performance against these standards is appropriate. 62. A basic objective of a CPA firm is to provide professional se rvices to conform with professional standards. Reasonable assurance of achieving this basic objective is provided through a) Continuing professional education. ) A system of quality control. c) Compliance with generally accepted reporting standards. d) A system of peer review. Answer B is correct because a system of quality control is necessary to provide a CPA firm with reasonable assurance that it is conforming to generally accepted auditing standards. 63. Which of the following types of services is most directly designed to improve the quality of information, or its context, for decision makers? a) Assurance services b) Attestation services c) Audit services d) Consulting services Answer A is correct because the Special Committee on Assurance Services (the Elliott Committee), defined assurance services as independent professional services that improve quality of information, or its context, for decision makers. The Elliott Committee defined assurance services as: â€Å"Indepe ndent professional services that improve the quality of information, or its context, for decision makers. † Assurance services include all attestation (including audit) services, plus a variety of other services which will be developed in the future; note, however, that tax and consulting services are not considered assurance services. 4. In performing an attestation engagement, a CPA typically a) Supplies litigation support services. b) Assesses control risk at a low level. c) Expresses a conclusion about the assertion on the subject matter. d) Provides management consulting advice. Answer C is correct because, when performing an attest engagement, a CPA expresses a conclusion about the assertion on the subject matter. 65. Which of the following professional services would be considered an attest engagement? a) A management consulting engagement to provide computerized advice to a client. ) An engagement to report on compliance with statutory requirements. c) An income tax en gagement to prepared tax returns. d) The compilation of financial statements from a client’s accounting records. Answer B is correct because a report on compliance with statutory requirements might be structured as an attest engagement in which the required written assertion relates to such compliance. 66. The technical standards that apply to consulting services engagements require the practitioner to do all of the following except a) Maintain independence from the client. ) Give support for and clearly identify an estimates any quantifiable results that are based on estimates. c) Obtain an understanding concerning the nature, scope, and limitations of the consulting advisory services engagement to be performed. d) Take no position which might impair the practitioner’s objectivity. Answer A is correct because independence is not required. 67. A CPA firm’s personnel partner periodically studies the CPA firm’s personnel advancement experience to ascertain whether individuals increased degrees of responsibility. This is evidence of the CPA firm’s adherence to prescribed standards of a) Quality control. b) Due professional care. c) Supervision and review. d) Fieldwork. Answer A is correct because the seventh quality control standard requires that a firm establish policies and procedures pertaining to personnel advancement. 68. Williams Co. , a large international CPA firm, is to have an â€Å"external peer review. † The peer review will most likely be performed by a) Employees and partners of William Co. who are not associated with the particular audit being reviewed. ) Audit review staff of the Securities and Exchange Commission. c) Audit review staff of the Philippine Institute of Certified Public Accountant. d) Employees and partners of another CPA firm. . Answer C is incorrect because the Philippine Institute of Certified Public Accountants does not have an audit review staff available for peer reviews. 69. The ob jective of quality control mandates that a public accounting firm should establish policies and procedures for professional development which provide reasonable assurance that all entry-level personnel a) Prepared working papers which are standardized in form and content. ) Have the knowledge required to enable them to fulfill responsibilities assigned. c) Will advance within the organization. d) Develop specialties in specific areas of public accounting. Answer B is correct because one of the quality control considerations for a firm of independent auditors is that the policies and procedures for professional development should be established to provide reasonable assurance that personnel have the knowledge required to enable them to fulfill responsibilities assigned. 0. A CPA establishes quality control policies and procedures for deciding whether to accept a new client or continue to perform services for a current client. The primary purpose for establishing such policies and pro cedures is a) To enable the auditor to attest to the integrity or reliability of a client. b) To comply with the quality control standards established by regulatory bodies. c) To minimize the likelihood of association with clients whose management lacks integrity. ) To lessen the exposure to litigation resulting from failure to detect irregularities in client financial statements. Answer C is correct because policies and procedures should be established for deciding whether to accept or continue a client in order to minimize the likelihood of association with clients whose management lacks integrity. 71. Within the context of quality control, a primary purpose of personnel management activities is to enable a CPA firm to provide personnel within the firm with a) Technical training that assures proficiency as an auditor. ) Professional education that is required in order to perform with due professional care. c) Knowledge required to fulfill assigned responsibilities to consulting en gagements. d) Knowledge required in order to perform a peer review. Answer C is correct the quality control standards relate to a firms accounting and auditing practice. 72. A CPA in public practice must be independent in fact and appearance when providing which of the following services? |Preparation of a |Compilation of |Compilation of | | |tax return |financial forecast|personal financial| | | | |statements | |A |Yes |No |No | |B |No |Yes |Yes | |C |No |No |Yes | |D |No |No |No | Answer D is correct. An auditor need only be independent when providing attestation services. Preparing tax returns and compiling forecasts or financial statements are not considered attestation services, therefore the CPA need not be independent. 73. The first general standard requires that the examination of financial statements is to be performed by a person or persons having adequate technical training and a) Independence with respect to the financial statements and supplementary disclosure. b) Ex ercising professional care as judged by peer reviewers. ) Proficiency as an auditor which likely has been acquired from previous experience. d) Objectivity as an auditor as verified by proper supervision. Answer C is correct because the first general standard requires that the examination be performed by a person or persons having adequate technical training and proficiency as an auditor which has been achieved by formal education and by previous experience. 74. Rogers Co. , CPAs, policies require that all members of the audit staff submit weekly time reports to the audit manager, who then prepares a weekly summary work report regarding variance from budget for Rogers’ review. This provides written evidence of Rogers Co. ’s professional concern regarding compliance with which of the following generally accepted auditing standards? a) Quality control. b) Due professional care. c) Adequate review. d) Adequate planning. Answer D is correct because the weekly time rep orts are being used to meet the first standard of fieldwork. The work is to be adequately planned, and assistants, if any, are to be properly supervised. Thus, the budget is prepared during the planning stage of the audit and the analysis of variances from budget is used as a part of the supervision process. 75. The third general standard states that due care is to be exercised in the performance of the examination. This standard means that a CPA who undertakes an engagement assumes a duty to perform each audit a) As a professional possessing the degree of skill commonly possessed by other in the field. b) In conformity with generally accepted accounting principles. c) With reasonable diligence and without fault or error. d) To the satisfaction of government agencies and investors who rely upon the audit. Answer A is correct because the level of skill necessary is that commonly possessed by other professionals in the same employment. 6. The exercise of due professional care requi res that an auditor a) Examine all available corroborating evidence. b) Critically review the judgment exercised at every level of supervision. c) Reduce control risk below minimum. d) Attain the proper balance of professional experience and formal education.. Answer B is correct because the exercise of due professional care (the third general standard) requires critical review at every level of supervision of the work done and the judgment exercised by those assisting in the audit. 77. When an accountant is not independent, the accountant is precluded from issuing a a) Compilation report. b) Review report. c) Management advisory report. d) Tax planning report. Answer B is correct because AR 100 requires the accountant who performs a review to be independent (because it is an attestation service). 78. If requested to perform a review engagement for a nonpublic entity in which an accountant has an immaterial direct financial interest, the accountant is a) Independent because the f inancial interest is immaterial and, therefore, may issue a review report. ) Not independent and, therefore, may not be associated with the financial statements. c) Not independent and, therefore, may not issue a review report. d) Not independent and, therefore, may issue a review report, but may not issue an auditor’s opinion. Answer C is correct. Reviews are a form of attestation service, and an accountant may not maintain independence when an immaterial direct financial interest is held in a client when performing attestation services. 79. The concept of materiality would be least important to an auditor when considering the a) Effects of a direct financial interest in the client upon the CPA’s independence. b) Decision whether to use positive confirmations of accounts receivable. c) Adequacy of disclosure of a client’s illegal act. d) Discovery of weakness in a client’s internal control structure. Answer A is correct because the auditor may not hav e any direct financial interest in a client, regardless of materiality. Don’t waste time! Our writers will create an original "Standards For Accounting and Review Services" essay for you Create order