Conservation of biological Diversity Essay Example for Free

Conservation of biological Diversity Essay Conservation of biological diversity is the most important aspect on the globe since all demands of human existence are entirely dependent on it. Domestic, industrial, and leisure considerations of human existence are derived from nature. Recently, the focus on biodiversity conservation has increased owing to the greater levels of understanding on the local and international significance of conservation. Since the first United Nations Convention on Human Environment held in Stockholm 1972, the disparities between conservation and development have come to the lime light with great emphasis (Clifford Clifford, 61-62). However, conservation analysts have continued to differ over the overall effects of the international conservation rules in enhancing harmony that inculcates human being as a subcomponent of the ecosystem in which they exist. Whereas misunderstanding and misinterpretation of the term conservation has recurred for a long time, UNEP points out that it is the overall use of biological resources while enhancing their resilience to enhance inter and intra generational equity. The term conservation has been used interchangeably with preservation a notion which is totally wrong. The later denotes taking care of the biological diversity without exploiting them or their proceeds. Biological diversity (biodiversity) is a term used to indicate variations of life forms within a given ecosystem, biome or the whole earth. It also encompasses the variability of living organisms from all sources, that include inter alia, terrestrial, marine, and other aquatic and ecological complexes that they are part. This includes diversity within species, between them, and ecosystems (James Kim et al, 193-195). 2. Overview of the paper This paper explores conservation of biological diversity with an aim of establishing the existing conservation strategies present on a global scale and assessing their effectiveness. Tracing the origin of the concerns for conservation, the paper uses statistics to indicate the current situation of biodiversity conservation and threats globally. To add to that, it explores the policy and legislative framework to address the threats on a global scale and their domestication by various states. Using examples, the paper seeks to establish the future of conservation and the factors that will determine effective conservation of the biological diversity. 3. Background and statistics Conservation of biological diversity has existed since historic times where most of the communities lived and co-existed with the natural flora and fauna without posing any threat to it. Notably, after the settling of the Red Indians in Northwest Coast and Southwestern regions of North America, they totally relied on the wild without causing any threat to them. However, the modern conservation ideals are mostly linked to the first United Nations Convention on Human Environment which was held in Stockholm Sweden in 1972 (Clifford Clifford, 102-105). It was this meeting that resolved to form the United Nations Environment Program to act as the main body responsible for environment and conservation globally. Conservation biologists have indicated that the world is threatened with extinction than any other period in history. Global extinction is estimated to be 10, 000 higher than the natural background extinction rate. 32% of all the global surviving amphibians are threatened with extinction. Over the last 50 years, it is estimated that two-thirds of all the mammal genera weighing about 44 Kg (97lb) have become extinct. To add to that, 12% of all birds in the globe and 23% of all mammals are listed in the IUCN Red Data Book. By the year 2000, about 27% of the entire world coral reefs had collapsed and by 2050 extinction rates will range from 15% to 37% for all the planet species (IUCN Commission on Ecosystem Management, 60-65). Of greater concern is that about 70% of all the studied plants have been designated as threatened or endangered. 4. Threats to conservation of biological diversity a) Industrial and Agricultural activities Since industrial revolution, advancement in technology has heightened the rate of natural resources exploitation from the natural system. This increase in exploitation has directly or indirectly affected the flora, fauna, or their habitat with a great extent. Currently, massive whaling industries in the pacific have resulted to the great decline of the species. After the discovery of â€Å"new lands† (currently North America), the British industrialists embarked on large scale harvesting of the forest products that threatened vast species of flora and fauna in the region. Of greater concern, is the wildlife products sale and use that have endangered biodiversity like the Tragelaphus speke, Myotis leibii, Lamptetra bifrenatus, Ambystoma opacum, Crotalus horridus, and Sterna dougalii among others. In addition species like Gavia, immer, Martes americana, Notropis bifrenatus, and Clemmys guttata have become threatened with time (Mark, 280-300). Agricultural activities on the other hand have encroached into most of the biodiversitys habitats due to the demand from the rising population to be fed. At this point, agriculturalists have shallowly argued that it is more important to feed the people as opposed to conservation. To add to that, modern agricultural activities have resulted to use of inorganic and toxic agro-chemicals that poison the flora and fauna. Pesticides and fertilizer remnants are easily swept to the aquatic ecosystems during the rainy seasons killing or inducing mutations in the biological systems. b) Pollution As indicated earlier, industrial productions most negative effect is probably pollution emitted to the natural systems. Notably, production of goods is operated on a totally capitalistic note where reduction of production costs is strongly emphasized. As a result, pollution control and waste management has taken a back hand in most of these industries and urban establishment. Therefore, they release most of their wastes directly into the ecosystems where massive poisoning of flora and fauna takes place. During the United Nations Convention on Environment and Development in 1992 at Rio-de-Janeiro, agenda 21 indicated the great need to control pollution by the member states. Of greater concerns was the direct emission of heavy metals that undergo bio-magnification and bio-accumulation to the environment. These toxicants have long tern effects and shift upwards to affect all level of food chain in an ecosystem. Glenn et al (540-545), emphasis the earlier connotation of the Silent springs on the trans-boundary nature of pollutants which results to extended impacts on a global scale. Rachael Carson found out that even after chemicals are used, they are transported via environmental dynamics to far places like the Polar Regions where she noted extensive death of penguins. c) Monopolistic application of conservation policies Notably, conservation of biodiversity has become a hard nut to crack due to lack of harmony in the overall design and application of conservation consideration between states. Though diplomacy has recently taken an upper hand in ensuring amicable resolution of conflicts, conservation of biodiversity still lags behind. This has been prompted by the varying priorities by different administrations and countries authorities’ consideration. This has especially been noted with the migratory birds in the world where they shift to various regions during different seasons. According to David (254-257) about 50% of the birds found in the Northern Hemisphere migrate towards the tropics during winter and back in springs. David continues to say that the Bar Tailed Godwit and the Sooty Shearwater have especially been under great threat from massive wetlands destruction. To add to that, Mara and Serengeti ecosystems (seventh wonder of the world) is under threat due to extensive destruction of forests that supply water to the fragile downstream ecosystem. 5. International laws, regulations and policy framework a) UNEP (United Nations Environmental Program) As indicated earlier, the United Nations Conference on Human Environment which resulted to formation of UNEP was the main beginning for conservation concerns. The body was established with the overall mandate of coordinating all environmentally related issues globally. It was especially charged with the responsibility of ensuring that conservation of biodiversity was strictly enhanced. As a result, it organized the Convention on Biological Diversity that was held in Rio-De-Janeiro in the year 1992. The latter is considered to be the most comprehensive meeting in the history of conservation as it formed the main guidelines for conservation of biodiversity in the member states which it broke into three main considerations: (1) Conservation of biological diversity by the member states with short and long term considerations (2) Sustainable use of its components (3) Fair and equitable sharing of the proceed resulting from consideration (2) It formed the main platform for the later conservation initiatives like Cartagena protocol and played a key role in establishment of Kyoto protocol. Holistically, the Convention on Biological Diversity is envisaged on precautionary principle which calls for greater concern and study of all impacts that would result to the biodiversity destruction upon establishment of various projects (European Union, 9-12). b) Ramser Convention (The Convention on Wetlands of International Importance) This convention was established to assist in conservation of wetlands that have international importance. Notably, most of the wetlands have usefulness that goes beyond their territorial jurisdictions either culturally, economically, scientifically, and have extensive recreational values. The convention came to force in 1975 and by the year 2000, about 1, 630, 000 square kilometers in 1, 021 sites had been designated. Canada has the greatest area of designated wetlands of 130, 000 square kilometers. Notably, this convention has particularly assisted the migratory bird species that occasionally uses these wetlands (William James et al, 495-500).

Two Step Extraction Of Pyrethrins From Pyrethrum

Two Step Extraction Of Pyrethrins From Pyrethrum The experimental determination of the concentration and yield of pyrethrins from chrysanthemum pyrethrum flower is usually carried out with chromatographic techniques; and accordingly, a lot of methods have been developed over the years [Wang et.al, (1997)]. These include high performance liquid chromatography (HPLC) [Todd et.al, (2003); Essig and Zhao, (2001b)], gas chromatography (GC) [Essig and Zhao, (2001a)] and supercritical fluid chromatography (SFC) [Wenclawiak and Otterbach, (1999)]. GC was chosen for convenience in this study. The first-step involves using n-hexane as solvent to extract the pyrethrins from the solid sample (grounded and unsieved with particles size of about 30 meshes), and then the second-step, a purification step involves the use of supercritical carbon dioxide as solvent to obtain the pyrethrins from the crude hexane extract (CHE). The hexane extractions (100g sample size), in a water bath at controlled temperatures and vigorous stirring, generated pyrethr ins concentrations varying from 69.85 95.50mg/ml and yields of 0.85 3.76% of the dry weight. Extraction efficiencies under several conditions were investigated and the optimum extraction condition was 400C in 4hrs. Compared with the product from the factory, several undesirable components exist in the CHE. The SFE was carried out with a self built unit (extraction vessel of 120ml) with a sample size of 40ml of CHE. Concentrations of 57.25 93.79mg/ml and yields (after the second extraction) of 0.99 2.15% were obtained; with the optimum condition being 350C at a pressure of 20MPa in 2hrs. Compared with the product from the factory, this sample contains two extra components (Tricosane and Tetracosane) also used in insect control. Key words: Solvent extraction; supercritical carbon dioxide; pyrethrins; two-step extraction; crude pyrethrins extract Introduction Pyrethrum flowers are from the Chrysanthemum genus and are known commercially as painted daisies, painted ladies, buhach, chrysanthemum cinerariaefolium, ofirmotox, insect powder, Dalmatian insect flowers, or parexan. It is believed to be recorded first in Dalmatia [Visiani, (1842-1852)]. However, others contend that its insecticidal activity was first proven by Antun Drobac (1810-1882) [Bakaric, (2005)]. Yet there are claims that it was first identified as having insecticidal properties around 1800 in Asia [Jeanne, (2009)]; and that the Crushed and powdered plants were used as insecticides by the Chinese as early as 1000 BC [Amrith, (2004)]. The flower contains about 1-2% pyrethrins by dry weight, but approximately 94% of the total yield is concentrated in the seeds [Casida and Quistad, (1995)]. The chemical structure of the active ingredients, pyrethrins I and pyrethrins II was identified in 1924 [Chandler, (1948); Coomber, (1948)]. Kenya is the worlds main producer today with more than 70% of the global supply [Jones, (1973)]. The natural active ingredients are referred to as Pyrethrins; consisting of cinerin I, jasmolin I, pyrethrin I, cinerin II, jasmolin II and pyrethrin II. The first three (chrysanthemic acid esters) are referred to as pyrethrins I (PYI), and the rest (pyrethric acid esters) as pyrethrins II (PYII) [Essig and Zhao, (2001a)]. Pyrethrins, though insoluble in water, are soluble in many organic solvents [WHO, (1975)]. They are non-volatile at ambient temperatures; non-toxic to mammals and other worm-blooded animals; highly unstable in light (photodegradable); biodegradable; but toxic to aquatic animals [Todd et.al, (2003); Chen and Casida, (1969); WHO, (1975)]. Their usage is mainly in biological crop protection; domestic insecticides [Gnadinger, (1936)]; and the formulations of synthetic pyrethroids [Todd et.al, (2003)]. Although pyrethrins are soluble in a number of organic solvents (benzene, hexane, petroleum ether, alcohol, acetone, meth anol, chlorinated hydrocarbons, etc) other considerations (practical, economic and environmental concerns) limit the usage. These considerations reduce the choices to just few. One of the qualities of Hexane in extracting pyrethrins is its ability to effectively dissolve the active ingredients minus contaminants. Another is that its removal from the concrete is achieved at lower temperatures; limiting degradation due to prolonged heating. Again, its low boiling point is a needed quality and it can be recycled, reducing the weight of the concrete. Above all, it is inexpensive, considered environmentally friendly, less toxic, non-corrosive, and non-reactive; traits which make it the dominant solvent adopted, especially for processing plant (biological) materials (products) which are often thermally labile, lipophilic, and non-volatile and are required to be kept and processed at around room temperatures. Carbon dioxide (CO2) has a critical temperature of 31oC which makes it particular ly an attractive medium for these kinds of tasks. Though other supercritical fluids (SCFs) show critical temperatures in this critical state and can be adapted as solvents, they are often difficult to handle and obtain in pure state, may be toxic, explosive or ecologically unsafe. Supercritical carbon dioxide (Sc-CO2) is by far, the most extensively used due to its non-toxic, inert and non-flammable nature. It is also natural, inexpensive, plentiful, non-toxic and inflammable and generally environmentally accepted [Schneider et.al, (1980)]. Its most important properties are enhanced density, viscosity, diffusivity, heat capacity and thermal conductivity. Higher densities contribute to greater dissolution of compounds while low viscosities enable easy penetration into samples and facilitation of flow of extracted (targeted) molecules from the source materials with fewer hindrances [Dunford et.al, (2003)]. Diffusivity offers easy and faster transport through samples; hence offers bett er extraction strengths; and dissolved ingredients are also easily separated from the supercritical solvent by drop in pressure [Fattori et.al, (1988)]. Sc-CO2, for the above and many reasons used as solvent in extraction saves both time and money while retaining overall extraction precision and accuracy with high purity and healthy products that are of excellent quality [Raventos et.al, (2002); Mohamed and Mansoori, (2002)]. Expectedly, a lot of research is now focused on the extractions of plant materials with supercritical carbon dioxide due primarily to the global growing solvent (organic) regulations and more importantly, the economic benefits (in terms of low operating temperatures; faster extractions and easier purifications, and of course better product quality). Stahl and Schutz [Stahl and Schutz, (1980)] extracted pyrethrins with CO2 and proposed that in the 20 °C to 40  Ã‚ °C temperature range decomposition (usually associated with pyrethrins extraction) does not occu r. Sims patented in the US, an extraction of pyrethrins using liquid carbon dioxide [Sims, (1981)] and Wynn and others patented using Sc-CO2 [Wynn et al. (1995)]. Wenclawiak and coworkers compared extracts obtained with ultrasonic (USE) and Soxhlet extractions (SEX); with hexane and Sc-CO2 extractions (SCE) and reported that direct extraction with SCE gave better pyrethrins content [Wenclawiak et.al, (1995)]. 2. 0. Experimental 2.1. Materials and Chemicals Grounded chrysanthemum (light green with a characteristic smell) sample and two pyrethrum concretes (yellow) were obtained from Yunnan Juxiang Natural Plant Products Company in China. The pyrethrins content of the concretes was claimed to be 50.0% (29.50% PYI and 20.50% PYII) and 85.15% (46.33% PYI and 38.82% PYII). Six individual standard solutions (using standard addition method) were prepared (from the 85.15% PY concrete-higher content, less impurities) for standardization of the analytical method. Analytical grade hexane (97.0%) and Ethanol (99.7%) were purchased from Sinopharm Chemical Reagent Co. Ltd in China, and used directly without any pre-treatment. CO2 (99.0 %) gas was supplied by Xin Hongli Gas Company also in China. 2.2. Experiments Three different experiments were performed: To establish the standard/calibration curves for determining the components, To implement hexane extraction and determine the yield of total PY in the grounded sample, and To implement SFE and determine the yield of total PY in the CHE. 2.3. Establishing Standard Curves The GC (Agilent) conditions used for establishing the standard curves are as follows: split injector with 20:1 split ratio at 2500C; Nitrogen as carrier gas at 1.6mL/min  ¬Ã¢â‚¬Å¡ow rate; injection volume of 0.1  µL; temperature program started at 1800C, kept for 11 minutes, heated at 100C/ min to 2000C, kept for 8 minutes, heated to 210 0C at 100C/min, kept for 18 minutes, then heated to 2450C at 30 0C/min, maintained for 4 minutes; FID detector; HP-5 Column, 30 mm 0.32 mm id., 0.25  µm  ¬Ã‚ lm thickness. This column was chosen because it gives the best resolution, identi ¬Ã‚ cation and quanti ¬Ã‚ cation for products containing OH and C=O [Rosana, (2003)]. 2g (85.15% concrete obtained from the company) of the extract was transferred into a 100mL flask containing 10mL ethanol, and then made up to the final volume of with ethanol and mixed well. Six aliquots (1mL, 2mL, 4mL, 8mL, 16mL and 32mL) of this solution were transferred into a 50mL flask each and diluted with et hanol again to the mark. We then calculated the concentrations of the PY in each aliquot, considering the percentage of each group (PYI and PYII) in the sample provided (Table A1 in the Appendix), injected (with a micro syringe) 0.1 µL of each solution into the GC after filtering (0.45-ÃŽ ¼m membrane filter) and recorded the elution times and corresponding peak areas (Table A2); subsequently, established the standard curves to express the relationship between the areas produced by the GC and the concentrations (Figure 2). 2.4. Hexane Extraction We extracted pyrethrins (from 100g of grounded sample of particle size of about 30mesh) with hexane in a water bath (YUHUA, DF-101S) in batches at different temperatures (35oC, 40 oC, 45 oC, 50 oC, 60 oC and 70 oC) and times (3hrs, 4hrs, 5hrs, 6hrs and 7hrs) in a 1000mL round-bottom flask, installed with a condenser. Agitation was achieved by stirring vigorously with three big size magnetic stirrers at a speed of 20rpm. The hexane was then removed from the pyrethrin concrete with a rotary evapourator (YUHUA, RE-2000B) at a temperature of 35 oC at a speed of 185rpm to obtain concentrated Crude Hexane Extract (CHE). Each concentrated sample was thereafter, filtered (0.45 µm) and 0.1 µL analyzed (Tables A3). This method has the advantage that the solvent is repeatedly recycled and temperature can be controlled. It offers a light coloured product with high recovery rate of pyrethrins; however, not only the desired components are extracted (Figure 3). Other soluble and hydrophobic sub stances (waxes and pigments) are also extracted [Kiriamiti et al, (2003)]. The solvent is removed by vacuum at lower temperature and the waxy thick mass left is the concrete; composed of essential oils and other oil soluble (lipophilic) materials. 3.0. Results and Discussion 3.1. Extract The extracts (CHE) contain pigments, fixed oils and waxes whose colour is deep yellow with characteristic smell. It also contains several undesired components (Figure 3) compared with the pure sample from the factory (Figure 1). 3.2. Effect of Extraction Temperature Temperature has long been reported to be a crucial factor in the extraction of natural pyrethrins [Atkinson et.al, (2004)]. Pyrethrins are sensitive to temperature (thermo labile) and are therefore, unanimously reported to degrade above 40oC [Stahl and Schuzt, (1980); Gourdon and Romdhane, (2002); Wynn et al, (1994)]. We investigated the effect of different extraction temperatures (40oC, 50oC, 60oC and 70oC) in fixed extraction times (5 hr gave better results than 6hr and 7hr). Our results conform to the reports (refer to Figure 4 and Table A3); the best yield (1.42) and PYI: PYII ratio (4.75) is at 40oC (but the best PYII yield-0.33 is at 70oC). This suggests that targeted components are extracted effectively at this temperature (40oC), above which two problems occur (separately or simultaneously): one is the extraction of more undesirable components at the expense of pyrethrins and the other is the decomposition of pyrethrins to form iso-pyrethrins [Stahl and Schuzt, (1980); Stahl, (1998); Gourdon and Romdhane, (2002); Wynn et.al, (1994)] thereby reducing the yield as seen. 3.3. Effect of Stirring We compared the effect of two stirring methods on extraction yield: the first with one magnetic stirrer and the second with three magnetic stirrers. The results are shown in Table A4, confirming that stirring improves extraction yield by facilitating the dissolution of the active ingredients and the effective distribution of heat. The extractions (at 40oC in 5hr) were repeated severally to ensure reproducibility and accuracy. 3.4. Effect of Extraction Time We further investigated the effect of extraction time by fixing the extraction temperature at 40oC with three magnetic stirrers; to establish the optimum extraction time (our initial time parameters were 5hr, 6hr and 7hr in which 5hr was the best). From Figure 5, the extraction yield increases steadily from 3hr to a peak at 4hr (see data in Table A5). Within this range, more desired components are extracted but after 4hr the yield decreases indicating that with prolonged time, even at the safest extraction temperature (40oC), less and less desired components are extracted and/or they decompose resulting in the decrease in yield. The drop in yield is consistent from 4hr (3.76%) to 6hr (2.15%). This implies that the optimum time (within the times investigated) is not 5hr as initially expected but rather 4hr. However, the ratio of PYI: PYII is best in 6hr (5.14). From 3hr to 4hr, the yield for both PYI and PYII appreciated but the increment in PYI (0.74) is greater than that of PYII (0. 38) hence the drop in the ratio. Between 4hr and 5hr, there is decrease in both PYI and PYII yields. Again, the decrease in PYI (0.98) is greater than that of PYII (0.49) accounting for the drop in ratio. The same reason accounts for the drop in ratio from 5hr to 6hr. 3.5. Effect of Concentrating CHE The effect of concentrating the CHE, on both PYI and PYII yield was analyzed (Table A6). Even though the concentrating temperature (35oC) was below the temperature above which PY degrades (40oC), there was loss in PY yield indicating degradation. This in our view may be due to the exposure of the pyrethrins directly to heat. As more hexane is evapourated, pyrethrins which hitherto, were locked in the solid sample matrix; surrounded by hexane and as such shielded from direct heat, is now in direct contact with the heat; and since they are sensitive to heat, decomposition is inevitable. However, the decomposition is small and negligible (about 2.25mg/ml which is about 0.41% of the total yield) due to perhaps the short concentrating time (about 30 min). 4.0. Supercritical Fluid Extraction (SFE) The CHE is too thick (viscous) to be used directly, coupled with the presents of undesirable components (waxes and pigments). A further treatment, usually with another solvent that only dissolve the desired compounds from the concrete is necessary. Different from other works, this study carried out SFE on the CHE as a purification step. We looked at the effect of time (hr), temperature (0C) and pressure (MPa) on extraction quality and yield. We have not studied the effect of particle size and pre-treatment; for information on this area, see the works of Kiriamiti and others [Kiriamiti et al, (2002)]. 4.1. Sample We concentrated the CHE in a rotary evapourator (from 500ml to 40ml at 185rpm in 30 minutes) for the SFE. 4.2. Extraction Process At the beginning of the extraction (Figure 6), all the check valves are closed except valve #2. This allows the CO2 gas into the compressor #4 (OLSB by Zheng Zhou Co. LTD, China) to be compressed, and the pressure gauges are allowed to attain equilibrium at a set pressure (10, 15 and 20 MPa). Valve #5 is then opened and the compressed fluid (Sc-CO2) is fed into the bottom of the extraction vessel #7 (120ml capacity) for up flow extraction configuration, containing the CHE (40ml) and metal fillings to facilitate effective contacting (increase internal mass transfer); which had earlier been heated to a set temperature (350C, 370C and 390C) and allowed to attain constant temperature with the help of the water bath #6. An appreciable time is allowed (5-10mins) for the total and complete dissolution of the crude extract and then valve #8 is opened and maintained until the pressure is in equilibrium again. The pressure reducing valve #9 is opened finally to collect the pyrethrins in the fl ask #10. A mass flow meter helps to determine the flow rate (1.5L/min). The extraction process is run and stopped at set times (1hr, 2hr and 3hr) and the extracts analyzed with the results tabulated (Table A8). The Metal fillings after each run were washed (10ml or 5ml of Hexane) and collected as residues to check for complete extraction. 5.0. Results and Discussion 5.1. Extracts The extracts did not contain visible pigments as was seen in the CHE. The colour was also different; light yellow to orange but the smell was similar. It also contained two extra components (Figure 10) which was found (by GC mass spectrometry) to be Tricosane (Peak 6) and Tetracosane (Peak 7). This was as a result of comparison with the pure sample from the factory (Figure 1). We compared the yield of the extracts after solvent extraction, concentrating the CHE and the SFE and noted that there was difference. The yield from the SFE was less due possibly, to the relatively high pressures used. Separation of the Sc-CO2 and the product is achieved by a drop in pressure. These high pressures have the tendency of causing the products to remain in the BPR or along the pipe (between the BPR and the flask in Figure 6) due to clotting as a result of the pressure drop; in spite of our use of heating tapes to minimize this effect. This is confirmed by the value of the yield in the residue (0.05%) which is far less compared to the difference between the concentrated sample yield (3.30%) and that of the SFE (2.15%, see Table A10). 5.2. Effect of Pressure According to Kiriamiti and others, the quantity of pyrethrins extracted decreases with decreasing pressure due to (i) the effect of density on the solubility of pyrethrins, (ii) the slightly high density of CO2, (iii) the moderate variation in density with pressure, and (iv) the very low undesirable extracted products [Kiriamiti et al, (2002)]. Our results conclusively conform to this (Table A7). The best extraction pressure was at 20MPa (at 350C and 2hrs). The concentration of PY also increases within this pressure range (from 81.34mg/ml 93.79mg/ml). Similar phenomenon was observed for both 1hr and 3hrs, indicating that more pyrethrins were extracted than the undesirable components within this pressure range (Figure 7). 5.3. Effect of Extraction Time The quantity of pyrethrins extracted decreases with extraction time at higher temperatures (above 400C), explaining that either pyrethrins decompose at these elevated temperatures or more undesirables are extracted instead. From Table A8, the yield and concentration of PY increase from 1hr to a maximum in 2hr (1.35% 2.15% and 90.42mg/ml 93.79mg/ml at 350C and 20MPa). Both however decrease in 3hr (1.24% and 82.30mg/ml, Figure 8). This implies that pyrethrins were extracted faster than the undesirables from 1 to 2hr but as the extraction proceeds, more undesirables were then extracted at the expense of the pyrethrins or which decompose. Therefore, prolonged extraction time rather favours the extraction of undesirables or promotes decomposition of pyrethrins. 5.4. Effect of Temperature Pyrethrins are thermo labile and therefore require being processed at low temperatures. Therefore, high extraction temperature does not only degrade the pyrethrins but also favours the extraction of undesirables (Figure 9). Within the temperature range we investigated, the best yield was at 350C (Table A9). 6. 0. Conclusions Pyrethrins are usually purified with organic solvents (ethanol, methanol, acetone, acetonitrile, petroleum ether etc) or their mixtures [Kasaj et.al, (1999); Henry et.al, (1999); Duan et.al, (2006)] which are generally expensive, flammable and explosive and above all, face strict legislative controls [Patrick, (2003)]. Alternatively, carbon dioxide is used to refining and purification. Sims proposed the use of liquid carbon dioxide [Sims, (1981)]. Similar to our method, Kiriamiti and others reported the extraction of pyrethrins from crude hexane extract (CHE) from batch extraction experiment using carbon dioxide [Kiriamiti et.al, (2003)] but with different extracting conditions and analysis method (HPLC). It is worth noting that our set up is very simple and less expensive coupled with the fact that our sample, after the SFE, contains two extra components (Tricosane and Tetracosane) not reported so far as part of the purification step. These components are not hazardous [Directive 67 /548/EEC] and have similar characteristics (may cause respiratory and digestive irritations), uses (as insecticides and biopesticides) and effects (they may not be detrimental to the insects but they certainly disrupt their behaviuor patterns and flushes them out for the more deadly pyrethrins I) as pyrethrins II [Chemcas.org; Chemnet.com; PPDB, (2011); Wylie, (1972); Lewis et.al, (1975)]. We developed a simple but efficient two-step procedure for the extraction of pyrethrins from chrysanthemum (pyrethrum flowers) and investigated the effect of various operating parameters on concentration and extraction yield. Based on the experimental results, we conclude that the two-step extraction of pyrethrins (first with hexane in a water bath and second with SC-CO2 as a purification step) is feasible and effective; the optimum extraction condition for high pyrethrins yield (3.76%) for the n-hexane extraction was 400C in 4hr; that vigorous stirring facilitated this; and that it is possible to achieve extraction yield of 3% or even more envisaged by Casida and Quistad. To our knowledge, this is the first time such a high recovery of pyrethrins is reported. A number of reasons may be attributed to this high recovery: i) extraction procedure, ii) choice of solvent, iii) vigorous stirring and above all, vi) the type of sample used. We further conclude that for the SFE (2.15% and 93.79mg/ml) the optimum conditions were 350C, at pressure of 20MPa in 2hr. 7.0. References Amrith S. Gunasekara, (2004): Environmental Fate of Pyrethrins, Environmental Monitoring Branch, Department of Pesticide Regulation, 1001 I Street, Sacramento, CA 95812 Atkinson B. L, Blackman A. J, and Faber H, (2004): The degradation of the natural pyrethrins in crop storage, J. Agric. Food Chem. 52, 280-28 Bakaric P, (2005): BuhaÄ  prirodni insekticid, Gospodarski list 17: 41-45 Casida J. E and Quistad G. B, (1995): Pyrethrum Flowers: Production, Chemistry, Toxicology, and Uses, Oxford University Press, New York Chandler S. E, (1948): The Origin and Early History of the Production of Pyrethrum in Kenya, Pyrethrum Post 1 (1): 10-13 Chen Y-L, and Casida J. E, (1969): Photodecomposition of Pyrethrin I, Allethrin, Phthalthrin, and Dimethrin, J. Agr. Food Chem. 17: 208-215 Coomber H. E, (1948): The Chemical Evaluation of Pyrethrum Flowers, Pyrethrum Post 1 (1): 16-19 Directive 67/548/EEC: The Dangerous Substances Directive (as amended) is one of the main European Union laws concerning chemical safety. Duan Wei, Zhengguo Li, Guomin Wang, Yingwu Yang, Yingguo Li and Yuxian Xia, (2006): Separation and purification of Natural pyrethrins by reversed phase high performance liquid chromatography, Chin. J. of Anal. Chem., vol.34, is.12, pp 1776-1779 Dunford N. T, Teel J. A and King J. W, (2003): A Continuous Counter Current Supercritical Fluid Deacidification Process for Phytosterol Ester Fortification in Rice Bran Oil, Food Research International 36, 175-181 Essig K and Zhao Z, (2001b): Method Development and Validation of a High-Performance Liquid Chromatographic Method for Pyrethrum Extract, J Chromatogr Sci 39 (4): 473-480 (8) Essig K and Zhao Z. J, (2001a): Preparation and characterization of a Pyrethrum extract standard. LC/GC 19(7): 722-730 Fattori M, Bulley N. R, and Meisen A, (1988): Carbon Dioxide Extraction of Canola See: Oil Solubility and Effect of Seed Treatment. J. A. O. C. S. 65, 968-974 Gnadinger C. B, (1936): Pyrethrum Flowers. 2nd Ed. McLaughlin, Gormley, King, Minneapolis, Minnesota Gourdon C and Romdhane M, (2002): Investigation in Solid-Liquid Extraction: Influence of Ultrasound, Chemical Engineering Journal 87, 11-19 Jeanne Roberts, (2009)  : Insecticide Treated Mosquito Nets and Malaria Prevention: Weighing the Benefits, Naming the Benefactors at www.celsia.com Jones G. D. G, (1973): Pyrethrum Production, In Pyrethrum; The Natural Insecticide, J. E. Casida (Eds.), Academic Press. New York, NY, 17-21 Kasaj D, A. Rieder, L. Krenn and B. Kopp, (1999): Separation and Quantitative Analysis of Natural Pyrethrins by High-Performance Liquid Chromatography, Chromatographia Vol. 50, No. 9/10 Kiriamiti H. K, Camy S, Gourdon C and Condoret J.S, (2003): Pyrethrin Extraction from Pyrethrum Flower using Carbon Dioxide, J. Supercrit. Fluids, 26, 193-200 Lewis W. J, Richard L. Jones, Donald A. Nordlund and Gross H.R JR, (1975): Kairomones and their use for the management of entomophagous insects: II Mechanisms causing increase in rate of parasitisation by Trichogramma spp, J. Chem. Ecol., vol. 1, No. 3, pp 349-360 Mohamed R. S and Mansoori G. A, (2002): The Use of Supercritical Fluid Extraction Technology in Food Processing, Featured Article, Food Technology Magazine, June, The World Markets Research Centre, London, UK Patrick Pelerin, (2003): Comparing Extraction by Traditional Solvents with Supercritical Extraction from Economic and Environmental Standpoint, Proceedings of the 6th International Symposium on Supercritical Fluids, TOME 1 Raventos M, Duarte S, and Alarcà ³n R, (2002): Application and Possibilities of Supercritical CO2 Extraction in Food Processing Industry: An Overview, Food Sci. Technology International, 8 (5), 269-284 Rosana V, (2004). Optimization of Gas Chromatographic-mass Spectrometric Analysis for Fatty Acids in Hydrogenated Castor Oil obtained by Catalytic Transfer Hydrogenation. Analytica Chimica Acta 505, 223-226 Schneider G. M. V, Stahl E and Wilke G, (1980): Extraction with Supercritical Gases, Verlag Chemie, Deerfield Beach, Basel Sims M, (1981): Liquid carbon dioxide extraction of pyrethrins, US Patent no. 4281171 Stahl E and Schà ¼tz E, (1980): Extraction of Natural Compounds with Supercritical Gases, J. Med. Plant Res. 40, 12-21 Todd G. D, Wohlers D, and Citra M, (2003). Toxicology Profile for Pyrethrins and Pyrethroids, Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, Atlanta, GA Visiani R, (1842-1852): Flora Dalmatica, Lipsiae; In Flora Europaea; vol 3, Cambridge University press Wang I. H, Subramanian V, Moorman R, Burleson J and Ko J. R, (1997). Direct Determination of Pyrethrins in Pyrethrum Extracts by Reversed-Phase High Performance Liquid Chromatography with Diode-Array Detection. J. of Chrom. 766, 277-281 Wenclawiak B. W and Otterbach A, (1999). Supercritical Fluid Extraction Kinetics of Pyrethrins from Flowers and Allethrin from Paper Strips. J. Anal. Chem. 365 8, 472-474 Wenclawiak B. W, Krappe M and Otterbach A, (1995): In Situ Transesterification of the Natural Pyrethrins, J. of chrom. A, 785, 263-267 World Health Organization, (1975): Data Sheet on Pesticides No. 11, Pyrethrins (www.inchem.org/documents/pds/pds/pest11_e.htm) Wynn H. T. P, Cheng-Chin C, Tien-Tsu S, Fong L, and Ming-Ren S. F, (1995): Preparative Supercritical Fluid Extraction of Pyrethrins I and II from Pyrethrum Flower; Talanta 42, 1745-1749

Sectionalism And The Breakup Of The U.s Essay -- essays research paper

Sectionalism and the Breakup of the U.S Throughout the early 1800's the country was split in many areas over many issues. Some of the more severe clashes between differing groups resulting from such issues as slavery, expansion, and internal improvement. With all of these controversial topics to worry about along with the vast diversity in the nation, caused separation and tensions throughout the country. The most prominent of the previous topics was slavery. This was an issue in the days of the bible and continues to be an issue in the middle 1800's. The divisions in the country brought about by slavery seem to be categorized into two main groups, abolitionists, and slave holders. These two groups also were divided geographically for the most part due to the South's need of slaves for cheap, and reliable man power, and the North, as it was not an agriculturally based economy and needed little in the way of unskilled laborers. It was very easy for the North to bash the South's slavery because their economy did not depend upon slavery. They had no slaves, no need for slaves, and saw slavery as inhumane and unlawful. The south, however, depended upon slavery as a basis of production, and the only way to operate large farms at the time, primarily being the large cotton plantations of the south. Several people tried to resolve the issue of slavery with compromises and bills that set clear rules and laws to appeal to both sides. The most prominent being the Missouri compromise. This document set the standard for slavery at the time. It also managed to further divide the country into two opposing groups geographically separated by the 36 degree 30 minute line. The bill clearly stated that no states above the proposed line shall have slavery, with exception to those already in existence. This meant that all new states being brought into the country from the west had a choice to have slavery if and only if they laid below the line. Obviously, the south did not really like the idea, as it allowed the northern non-slave states to outnumber the southern slave-states in the south as far as representation in the government was concerned. Another part of the slavery controversy was the moral issue and weather or not it w... ... sides. We see the best example of this in the Maysville Road article. There was a dispute over the proposed road, and weather or not it should be built with federal money. The government claimed that the road was for the benefit of the mail, and allowed easy passage through the mountains of Kentucky. Many people did not like the idea still because it represented federal money being distributed in unequal amounts to different states, along with non uniform benefits. This quickly set defined boudaries between the political parties of the time, and started a vast amount of tension between the two parties. By the end of the dispute, the opposed(Federalists) came out on top, and the road was never built, but it shows the first, strong, divergence in the populous of our nation since its conception. All of the above examples are all representative of issues of the time which played a large roll in sectionalism, and the breakup of the United States. Over the long run, it is a miracle that, with the vast spectrum of people in the country, we have managed to stay together, through thick and thin, driven by one common force, "Freedom."

The Short Story Theories Of Ed :: essays research papers

In both of the articles, each author is trying to share his view, or theory on the short story. The view of Edgar Allen Poe is very pessimistic toward the novel and other forms of long fiction, while B.M. Ejxenbaum takes a more analytic approach. Poe writes, 'The novel certainly requires what is denominated a sustained effort—but this is a matter of perseverance, and has but a collateral relation to talent.'; Is the main difference between the authors of short stories and those of novels that the novel writers are just non-talented over-achievers? Indeed, it does take talent to be able to convey a story with little or no build up, character development or falling action, but it also takes talent to do so, and the effort you put into a work, such as a novel, is your talent, and it is directly related through thought and emotional drive. Ejxenbaum uses much less opinion in his explanation of the differing styles of short fiction and those of novels. The novel is based off a history, or of travels, while the short story, which is generally more fundamental in form, is based off folklore and anecdotes. The short story must be written on the basis of a contradiction or contrast, and carries the weight of the story at the ending. The action of a novel falls before the ending, with a falling action following. Poe speaks of unity of effect, and how it is not appreciated or understood by the common mind, but also how it is important to the story for the central effect to gravitate toward the end. This finale must make sense with everything which came before. Ejxenbaum quote Poe several times to give insight into how Poe created his unique and famous effects and moods. Poe was a master at creating effect, in most cases one of mystery and gloom, which drove his poems and short fiction. But he also was a storyteller, and like any good storyteller, he forms plots. And with those plots, he forms his moods and effect. Ejxenbaum sums up this idea with, 'The particular attention paid to the unexpected in the finale and, connected with it, a story structured on the basis of a riddle or and error which holds back the significance of the plot mainspring until the very end.'; The effect cannot exist without the plot, and the plot cannot exist without the effect.

Wallace Stevens Harmonium and the Visual Arts :: Literature Art Papers

Wallace Stevens' Harmonium and the Visual Arts By the time Wallace Stevens moved to New York City in 1900 he had completed three years as a special student at Harvard, and had published a few poems in the Harvard Monthly and the Advocate (a literary journal at Harvard of which he was president). He continued to pursue a literary life in New York, but after an attempt at journalism and at the urging of his father (L59), he enrolled in New York Law School in the fall of 1901. In 1904 he passed the bar and eventually acquired a position in the insurance field after attempting to hang out his own shingle (Stevens, H., 77-8). He married Elsie Viola Moll (a woman also from Reading) in 1909 and in 1916 they moved to Hartford. Stevens was by this time working for the Hartford Accident and Indemnity Co., the insurance company he was to stay with for the rest of his career, becoming vice-president in 1934. Before leaving for Hartford, though, he caught the literary bug again (L 187) and by 1914 Stevens was submitting poetry again for publi cation and communicating with the editor of Poetry, Harriet Monroe (L 192). The thirteen years separating any serious poetic output on the part of Stevens might easily be accounted for by his early career in law and his desire to make a secure place for himself there. Above all a practical man, Stevens may have simply put a sustained effort at poetry aside for a time in order to avoid poverty, as he said he did for eight years after publishing Harmonium in 1923 (L 364). Perhaps he was "stewing" during this time, having a few life experiences and just generally maturing. Also, his courtship and marriage, which might also have been delayed for economic reasons, had taken place during this interval. Any or all of these variables could have worked to delay his poetic achievement. The turning point came, I believe, once Stevens came into close contact with modern artists and their works. Although there is no sustained discussion of visual art or influences in Stevens' letters, I will argue that the writing of Harmonium is in a sense bracketed by Stevens' exposure to Walter Arsenberg and his salon. It is my contention that Stevens wrote Harmonium while steeped in modern art and it's theoretical underpinnings and that the poems contained in his first book of poetry reflect certain modern visual sources.

Proliferation of Global Terrorism Essay

The Second Indochina War, popularly known as the Vietnam War, took place from 1965 to the 30th of April in 1975. It is a very memorable moment for the North Vietnamese military for they have achieved victory, which is in fact, the first ever major defeat of the United States in the field of military. The defeat of the United States, even with their remarkable military munitions and superiority, created a place in the minds of historians, teachers, students and other people. As such, political activists, contemporary journalists, militant teachers and socially conscious generation of students are inspired by this event to fight back against the Vietnam War (Gilbert, 2000). These people or generation, especially those who are intimidated and did not hold onto the leftist political agenda, generally is destructive and utilizes violent protests. Subversive propagandas are also used by these people to voice out their anger against the Vietnam War (Heineman, 1993).   It would be good thing for these young people to give their supports in order to achieve a military victory, but violence is not the means or should not be considered as an option. It is unnecessary for violence would only provoke another one to occur. Violence would only occur and reoccur, from one side to the other, resulting to a vicious cycle; something that is greatly unnecessary. It would be best if all the peaceful means would be exhausted first. If all fails, then we can consider violence as an option. But, as long as there are still other means, ways or options to take or consider, violence should not be considered. A well-thought action, not a reckless one, often results to greater achievements, if not the best. Part II – Dangers on a Global Scale   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   The Six-Day War which is commonly known as the 1967 Arab-Israeli War, is a major conflict that occurred between and fought by Syria, Egypt and Jordan, all which are Israel and Arab neighbors. In this war, soldiers or military forces from other countries also joined the battle and helped the Arab forces, such as those from Saudi Arabia, Iraq, Algeria and Kuwait.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   After the war, in 1967 where the Israel defeated the Arabs, the Palestinians who were displaced, tried to live in the places where they fled. The Palestinian population feared for their lives and wanted to live. They were also in state of calamity because of the strength of the troops and military forces from Israel. To run and conserve their lives was the best option that the Palestinians could do. The predominant Palestinian Population continued their lives in the West Bank. Almost 4,000 Palestinians stayed in the West Bank; all of them are refugees or those who fled to save their lives. Some stayed, and tried to fight back with the hope of winning, and greatly showing these people’s Palestinian nationalism, but their efforts were futile. The predominant Palestinian population that fled, may have contributed to their cause for they ensured to save their lives; the lives that would later on increase and ultimately create new Palestinian nationalists or future heroes of their people.   Those who stayed and fought back may not have been totally successful, but they contributed as well in buying time for their people to run and survive. World Politics Complex Interdependence Counter independence refers to the international relations. In circumstances, this affirms to the fortunes and inextricabilities of Robert Keohane’s and Joseph Nye’s ideas. These two theorists accepted that in the counter independence, the diverse and intricate connections and the interdependencies of the present states and the respective societies are increasing. On the other hand, while the complex interdependencies increase, the utilization of the state or societies military force decreases. Along with the decline of military usage, is the decrease of its force and power, which oftentimes becomes unbalanced though still important. There are three characteristics of the complex interdependencies which were determined by the theorists. These characteristics would be necessary for analysis. The first characteristic is the multiple channels which connect societies and may also include informal ties. The informal ties may occur between governmental elites and the nongovernmental elites. An example would communication of one government to the advanced industrial countries or non governmental elites meeting frequently. The second characteristics include the agenda of the interstate relationships. These relationships include multiple issues which are generally not arranged. There is a link of the issues regarding prioritization and the objective of the third characteristic. An example may include the foreign affairs agenda wherein the relevant issues regarding the government and foreign policies are tackled. The third characteristic brings about the decrease in the dependence on the military force and power in dealing with the international relations. The government does not use its military capabilities to resolve issues towards other governments within the region when the complex interdependence prevails (Baaklini and Desfosses, 1997). An example would be the use of peaceful means or negotiations to resolve a conflict.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Globalization and complex interdependence may be similar or would relate to one another in that an intricate relationship is formed or that there is an increase in the interconnections between people. In globalization, there is a need for advancement of the technology, transport and communication that would later on cause an economic, cultural or political junction, not unlike the complex interdependence which does not necessarily need any advancement in technology for a convergence may occur. References Baaklini, A. I., & Desfosses, H. (1997). Designs for Democratic Stability: Studies in Viable Constitutionalism. Armonk, New York: M.E. Sharpe, Inc. Gilbert, M. J. (2000). Vietnam War on Campus: Other Voices, More Distant Drums. Westport, Connecticut: Greenwood Publishing Group Incorporated. Heineman, K. J. (1993). Campus Wars: The Peace Movement at America State Universities in the Vietnam Era. New York: New York University Press.

Saint Patrick

Saint Patrick was born in Kilpatrick, Scotland, in the year 387. His parents are Calphurnius and Conchessa. When Patrick was sixteen, he was carried off into captivity by Irish marauders and was sold as a slave to a chieftan named Milchu in Dalriada. In Dalriada, he tended his master’s flocks in the valley of the Braid and on the slopes of Slemish. When he was working the fields, he acquired a perfect knowledge of the Celtic tongue. His master was a druidical high priest, in which gave Patrick an opportunity to become familiar with all the details of Druidism from whose bondage he was destined to liberate the Irish race. Warned by an angel after six years, he fled from his cruel master and bent his steps toward the west. He traveled about 200 miles to Westport. He found a ship ready to sail and after some rebuffs was allowed on board. In a few days he arrived in Britain, but now his heart was set on devoting himself to the service of God in the sacred ministry. After wandering in dense forest for twenty-eight days they were found by others and eventually Patrick made it home to his family. He remained with them for a few years, and then decided to pursue the priesthood in answer to dreams he had about returning to Ireland. After a number of years, while he was on a short visit to the continent, probably Gaul, his name was proposed to lead a missionary expedition to Ireland. He set out around the year 432 as a bishop, and went to the headquarters of the Ulaid in Emain Macha, and there established his first church at what is now Armagh. From there he traveled predominantly in the north and west and made many converts, and trained many priests. After some time, his integrity was questioned, resulting in an inquiry at the hands of the British bishops, but he was subsequently vindicated. As the Ulaid were pushed out of more and more territory, Patrick moved with them to spend his last days in Down, from which he wrote his Confession. He died March 17, 461, in Downpatrick, Ireland. Kilpatrick still retains many memorials of Saint Patrick. His feast day, St. Patrick’s Day, is March 17, or the day he died.