975 resultados para Radikalfänger, Isoselenazole, Hydroxylradikale, Cox, Lox
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Background: Cyclooxygenase-2 (COX-2) plays essential roles in inflammation. Previous studies have suggested associations between prostaglandin-endoperoxide synthase 2 (PTGS2) polymorphisms and prostaglandins production in asthma. Objective: We have invest
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Cyclooxygenase-2 (COX-2, encoded by the gene prostaglandin-endoperoxide synthase 2, PTGS2) is a key enzyme in the conversion of arachidonic acid to prostaglandins. The prostaglandins produced by COX-2 are involved in inflammation and pain response in diff
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The study was conducted in collaboration with the ECFC project of the FAO (BGD/97/017) in Cox's Bazar to develop a low cost solar tunnel dryer for the production of high quality marine dried fish. The study areas were Kutubdiapara, Maheshkhali and Shahparirdip under Cox's Bazar district. Three different models of low cost solar dryer were constructed with locally available materials such as bamboo, wood, bamboo mat, hemp, canvas, wire, nails, rope, tin, polythene and net. Size of the dryers were: 20x4x3 ft ; 30x3x3 ft and 65x3x3 ft with the costs of Tk. 3060, 3530, 9600 for dryer 1, 2 and 3, respectively having different models. The drying capacities were 50, 150, 500 kg for dryer 1, 2 and 3 respectively. The average temperature range inside the dryers were 29-43°C, 34-51°C and 37-57°C for dryer 1, 2 and 3 respectively as recorded at 8:30h to 16:30h. The relative humidity were in the ranges of 22-42%, 27-39% and 24-41 % in dryer 1, 2 and 3 respectively. The fish samples used were Bombay duck, Silver Jew fish and Ribbon fish. The total drying time was in the range of 30-42, 28-38 and 24-34 hours to reach the moisture content of 12.3-14.5, 11.8-14.3, and 11.6-14.1% in dryer 1, 2 and 3 respectively. Among these three fish samples the drying was faster in Silver Jew fish followed by Bombay duck and Ribbon fish in all the three dryer.
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Present status and future prospects of mackerel and tuna fisheries in Bangladesh were assessed during July 2003-June 2004. The work concentrated on the fishing gears, length of fishes, total landings and market price of the catch and highlighted the prospects of the fishery in Bangladesh. Four commercially important species of mackerels and tuna viz. Scomberomorus guttatus, Scomberomorus commerson, Rastrelliger kanagurta, and Euthynnus affinis were included in the study. About 95% of mackerels and tuna were caught by drift gill nets and the rest were caught by long lines (4%) and marine set-bag-net (1%). Average monthly total landing of mackerels and tunas was about 264 t, of which 147 t landed in Cox's Bazar and 117 t in Chittagong sites. Total catches of the four species in Cox's Bazar and Chittagong sites were found to be 956 and 762 t, respectively. The poor landing was observed during January-February and the peak landing was in November and July. Gross market value of the annual landing of mackerels and tunas (1,718 t) was found to be 1,392 latch taka. Nevertheless, the mackerel and tuna fisheries in Bangladesh are increasingly contributing to the marine fish production of the country and have very good potential for further expansion for both domestic and export market.
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Shrimp culture in Bangladesh has emerged as an important aquaculture industry over the last three decades although its culture in greater parts of the farming area is done in traditional ways. In the meantime, the government of Bangladesh has taken necessary measures along with the private sectors to increase production, upgrade processing industries and to promote export performance. Long supply chain in raw material collection, inadequate infrastructure facilities, poor level of cool chain and lack of adequate HACCP-based training on hygiene and sanitation of different groups of people involved in the field level are the main problems of quality loss of raw materials. Shortage of raw materials results in poor capacity utilization of the processing plants. The growth of bagda (P. monodon) hatchery has expanded rapidly over the last few years, remaining mostly concentrated in Cox's Bazar region is enough to meet the target production. However, there is a shortage of pelleted shrimp feed in Bangladesh. A large number of export processors are now producing increasing amounts of value-added products such as individually quick-frozen, peeled and divined, butterfly cut shrimp, as well as cooked products. The export earnings from value added products is about half of the total export value. About 95% of total fish products are exported to European countries, USA and Japan and the remaining to the Southeast Asia and the Middle East. Most of the EU approved shrimp processing industries have been upgraded with laboratory facilities and provided HACCP training to their workers. As of now, HACCP is applied on the processing plants, but to ensure the quality of raw materials and to reduce risks, shrimp farms are also required to adopt HACCP plan. There is increased pressure time to time from importing countries for fish processors to establish effective quality assurance system in processing plants. Fish Inspection and Quality Control (FIQC) of the Department of Fisheries while having moderately equipped laboratories with chemical, bio-chemical and microbiological testing facilities and qualified technical personnel, the creation of facilities for testing of antibiotics is underway. FIQC mainly supervises quality aspects of the processing plants and has little or no control over raw material supply chains from farm to processing plants. Bangladesh export consignments sometimes face rejection due to reported poor quality of the products. Three types of barriers are reported for export of shrimp to EU countries. These are:(1) government participation in trade and restrictive practices (state aid, countervailing duties, state trading enterprises, government monopoly practices), customs and administrative entry procedures (anti-dumping duties, customs valuation, classification, formalities, rules of origin); (2) technical barriers to trade or TBT (technical regulations, standards, testing, certification arrangement); (3) specific limitations (quantitative restrictions, import licensing, embargoes, exchange control, discriminatory sourcing, export restraints, measures to regulate domestic prices, requirements concerning marking, labeling and packaging).
Mass culture of marine diatom Skeletonema costatum (Greville) Cleve collected from the Bay of Bengal
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The growth of Skeletonema costatum in two artificial nutrient media was studied using various culture vessels. Skeletonema costatum was collected from the Cox's Bazar coast around the Bay of Bengal. Different growths stages i.e. lag phase, exponential phase, prestationary phase, stationary and death phase were observed during the culture period. The number of cells increased during the active division period and decreased after the beginning of the prestationary phase. The average densities of S. costatum in primary and secondary cultures were 0.55 x 10 super(6) cells mlˉ¹ and 0.93x10 super(6) cells mlˉ¹, respectively. In mass culture of S. costatum two, types of media were used. Highest cells densities of S. costatum cement tank culture were recorded 1.23x10 super(6) cell mlˉ¹ and 0.78x10 super(6) cells mlˉ¹ in their respective f/4 medium and commercial fertilizer medium. In the cement tanks culture fertilizer medium was found to be the best medium for mass culture of S. costatum in respect of production efficiency and culture stability.
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Spirulina is a filamentous cyanobacteria with many applications in food and drug industries, as a food in human, aquaculture, vet and poultry industries… . Semi and mass culture of Spirulina carries out in different countries. This study was carried out in five phases in order to produce this microalga in Iran. The first phase, Spirulina pure stock was imported from Indonesia. After identification of species, it was cultured in laboratory until we took 20 liters of biomass. The semi-mass culture was carried out in green house. Cell concentration and size of Spirulina were recorded during culture daily and their growth rates were calculated. After two weeks, when the size of Spirulina was suitable, biomass of Spirulina was harvested then accumulated Spirulina weighted and dried in 24 hours in laboratory. In order to microbiological study, the samples of Spirulina (dry and fresh) were cultured on blood agar medium and coliforms were counted. The chemical composition of produced Spirulina was measured by standard methods. Fatty acid and amino acid profiles were acquired by GC and HPLC instruments, respectively. The amount of chlorophyll in Spirulina was determined by spectroscopy method. Also astaxanthin pigment as an important carotenoid was measured by HPLC in Spirulina and Penaeus semisulcatus larvae fed on Spirulina. At final phase of this project, larva fed on produced Spirulina (biomass and dry powder) was compared to Z plus, microencapsulated Spirulina (M.C.F) and Chaetoceros algae as control. This experiment was carried from zoa to early post larvae stage then survival and growth rate of larvae were recorded. The growth rate of larvae was evaluated with ANOVA test and survival rate of treatments was assessed by Log Rank (Mantel –Cox) test. Also during larvae stage, two parameters of water such as nitrate and nitrite were measured in zoa, mysis and post larvae stages. The results of this study were shown that colifom counts were 1.85×106 and 92.3×105 coliform per ml in fresh and dry spirulina, respectively. Protein percent of dry spirulina was 50.93 % (dry weight) and the amount of astaxanthin in spirulina and larvae fed on spirulina were 0.21 and 0.01 mg/kg, respectively. The most survival rate of larvae were observed in zoa III (88.8%) with Z plus supplement treatment, in mysis III (76.5%) combination of Z plus and dry spirulina in comparative between treatments. Larvae growth (4.5mm) of control in early post larvae was the best.
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In order to minimize the number of iterations to a turbine design, reasonable choices of the key parameters must be made at the earliest possible opportunity. The choice of blade loading is of particular concern in the low pressure (LP) turbine of civil aero engines, where the use of high-lift blades is widespread. This paper presents an analytical mean-line design study for a repeating-stage, axial-flow Low Pressure (LP) turbine. The problem of how to measure blade loading is first addressed. The analysis demonstrates that the Zweifel coefficient [1] is not a reasonable gauge of blade loading because it inherently depends on the flow angles. A more appropriate coefficient based on blade circulation is proposed. Without a large set of turbine test data it is not possible to directly evaluate the accuracy of a particular loss correlation. The analysis therefore focuses on the efficiency trends with respect to flow coefficient, stage loading, lift coefficient and Reynolds number. Of the various loss correlations examined, those based on Ainley and Mathieson ([2], [3], [4]) do not produce realistic trends. The profile loss model of Coull and Hodson [5] and the secondary loss models of Craig and Cox [6] and Traupel [7] gave the most reasonable results. The analysis suggests that designs with the highest flow turning are the least sensitive to increases in blade loading. The increase in Reynolds number lapse with loading is also captured, achieving reasonable agreement with experiments. Copyright © 2011 by ASME.
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Cyanobacteria perform photosynthesis and respiration in the thylakoid membrane, suggesting that the two processes are interlinked. However, the role of the respiratory electron transfer chain under natural environmental conditions has not been established. Through targeted gene disruption, mutants of Synechocystis sp. PCC 6803 were generated that lacked combinations of the three terminal oxidases: the thylakoid membrane-localized cytochrome c oxidase (COX) and quinol oxidase (Cyd) and the cytoplasmic membrane-localized alternative respiratory terminal oxidase. All strains demonstrated similar growth under continuous moderate or high light or 12-h moderate-light/dark square-wave cycles. However, under 12-h high-light/dark square-wave cycles, the COX/Cyd mutant displayed impaired growth and was completely photobleached after approximately 2 d. In contrast, use of sinusoidal light/dark cycles to simulate natural diurnal conditions resulted in little photobleaching, although growth was slower. Under high-light/dark square-wave cycles, the COX/Cyd mutant suffered a significant loss of photosynthetic efficiency during dark periods, a greater level of oxidative stress, and reduced glycogen degradation compared with the wild type. The mutant was susceptible to photoinhibition under pulsing but not constant light. These findings confirm a role for thylakoid-localized terminal oxidases in efficient dark respiration, reduction of oxidative stress, and accommodation of sudden light changes, demonstrating the strong selective pressure to maintain linked photosynthetic and respiratory electron chains within the thylakoid membrane. To our knowledge, this study is the first to report a phenotypic difference in growth between terminal oxidase mutants and wild-type cells and highlights the need to examine mutant phenotypes under a range of conditions.
Consumption of fa cai Nostoc soup: A Potential for BMAA exposure from Nostoc cyanobacteria in China?
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Grown in arid regions of western China the cyanobacterium Nostoc flagelliforme - called fa cai in Mandarin and fat choy in Cantonese - is wild-harvested and used to make soup consumed during New Year's celebrations. High prices, up to $125 USD/kg, led to overharvesting in Inner Mongolia, Ningxia, Gansu, Qinghai, and Xinjiang. Degradation of arid ecosystems, desertification, and conflicts between Nostoc harvesters and Mongol herdsman concerned the Chinese environmental authorities, leading to a government ban of Nostoc commerce. This ban stimulated increased marketing of a substitute made from starch. We analysed samples purchased throughout China as well as in Chinese markets in the United States and the United Kingdom. Some were counterfeits consisting of dyed starch noodles. A few samples from California contained Nostoc flagelliforme but were adulterated with starch noodles. Other samples, including those from the United Kingdom, consisted of pure Nostoc flagelliforme. A recent survey of markets in Cheng Du showed no real Nostoc flagelliforme to be marketed. Real and artificial fa cai differ in the presence of beta-N-methylamino-L-alanine (BMAA). Given its status as a high-priced luxury food, the government ban on collection and marketing, and the replacement of real fa cai with starch substitutes consumed only on special occasions, it is anticipated that dietary exposure to BMAA from fa cai will be reduced in the future in China.
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非甾体类抗炎药(NSAIDs)是临床较常用的处方药,是高效的止痛、退热和抗炎药。NsADs有广泛的临床适应证,尤其适用于各种急、慢性关节炎,软组织风湿症、运动性损伤、头痛、痛经、拔牙后痛以及癌性疼痛等。因此,NsAIDs一直是世界上处方量最大的药物之一,包括我国在内的各国NSAIDs消耗量都呈明显上升趋势。仅疼痛控制部分,预计2007年就将达到300亿美元[l]。但是,大多数NSAIDs,尤其是我国目前使用的NSAIDs,都有较大的毒性和副作用。最新的分子生物学实验证明,各种NSAIDs起治疗作用的基础是通过抑制环氧合酶(cox),阻断致炎介质前列腺素类化合物的合成。环氧合酶至少包括两种同功酶(可能还有未被发现的新的亚类型),COX-1和COX-2。COX-1主要发挥生理性管家功能;COx-2主要为诱导型,在正常组织内活性极低,当受到某些细胞因子、促有丝分裂物质和内毒素刺激时大量表达,相应引起致炎介质的增加,使炎症加重。这些区别为设计兼具高抗炎活性和低毒性的药物提供了可能。阿司匹林是最早获得应用的NSAIDs,随后又出现一批其它NSADOs,最近美国FDA批准上市的罗非考昔,西乐葆是较好的COX-2选择性抑制剂,但是售价过于昂贵,从费用上考虑较难维持长期服用。至今我国还没有具有自主知识产权的COX-2特异性NSAIDs,服用的NSAIDs中,国外更新淘汰多年的毒副作用较大的药物仍占有较大比重,所以开发具有我们自主知识产权的新型NSAIDs迫在眉睫。鉴于COX-1,COX-2酶晶体结构明确,NSAIDs筛选模型确定,尤其是我国传统的中医药对炎症的独特认识,所以,凭借现代医学和化学知识,结合中国传统的中医药知识开发具有我们自主知识产权的新型NSAIDs是切实可行的。在研究过程中我们发现,在中国传统的中医药体系里,冰片是一种独特的药物,其主要成分为结构明确的龙脑、异龙脑。中医文献对其性质和应用详细的记载表明,其不仅广泛地用于抗风湿,而且其性质符合现代药物概念中的“靶向药物”概念。所以,如果合理设计使龙脑负载有抗炎结构化合物,可能会明显改善原药物的COX-2选择性,从而开发一种或几种COX-2特异性抑制剂。据此,又参考COX-2酶晶体结构,设计合成了其他结构的可能具有抗炎活性的药物分子。小茵香醇是龙脑和异龙脑的同分异构体和结构类似分子,我们选择该分子代替龙脑和异龙脑与布洛芬结合,并进行了活性测试和筛选,以深人了解该类分子。(1)设计并合成了含龙脑、异龙脑和小茵香醇结构的分子。相应结构见Tablel。(2)因为该类分子具有比较高的位阻,所以反应惰性较大,经过实验发现,在丁基锂/四氢吠喃反应体系或二环己基碳二亚胺仁甲氨基毗咙反应体系条件下,反应能够顺利进行。其中,二环己基碳二亚脚二甲氨基毗陡反应体系产率稍高。(3)针对几个主要反应详细探讨了分离纯化条件,为将来的放大实验或规模化制备提供了条件,并对所有产品进行了详细的结构表征。(4)通过“药物对小鼠腹腔巨噬细胞生成COX-1和COX-2的抑制作用”实验,对所获得的化合物进行了初步的活性评价,并得出如下结果:(a)在所设计的分子中,化合物3和化合物8分子表现出一定的COX-2选择性,其IC50COX-1/ IC50COX-2的比值分另为6.663和6.835,稍优于目前使用的第二代NSAIDs。见第七章Tablel,Table 2 and Figurel。(b)在所设计的分子中,化合物13,即布洛芬小菌香醇酷表现出最好的选择性;IC50COX-1/IC50COX-2比值为21.006,普遍超出目前使用的大部分NSAIDs,如果经过进一步的分子设计或修改有可能获得更好的结果。(c)化合物13与化合物9和化合物10相比较,选择性明显更好。即小茵香醇醋比龙脑酷和异龙脑醋表现出更好的靶向性。(d)从得到的结果可以看出,龙脑所负载的分子的选择性普遍比异龙脑要强,对于阿司匹林表现的尤为明显。(e)在中医药的文献和典籍中,关于小茵香醇性质和应用的记载很少,我们的研究结果表明它可能具有潜在的还不为我们所了解的特殊性质,我们的研究也可能会促进对该化合物的研究。(f)以佐剂关节炎模型对乙酰水杨酸龙脑醋进行了活性评价。
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Intervalley GAMMA - X deformation potential constants (IVDP's) have been calculated by first principle pseudopotential method for the III-V zincblende semiconductors AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs and InSb. As a prototype crystal we have also carried out calculations on Si. When comparing the calculated IVDP's of LA phonon for GaP, InP and InAs and LO phonon for AlAs, AlSb, GaAs, GaSb and InSb with a previous calculation by EPM in rigid approximation, good agreements are found. However, our ab initio pseudopotential results of LA phonon for AlAs, AlSb, GaAs, GaSb and InSb and LO phonon for GaP, InP and InAs are about one order of magnitude smaller than those obtained by EPM calculations, which indicate that the electron redistributions upon the phonon deformations may be important in affecting GAMMA - X intervalley shatterings for these phonon modes when the anions are being displaced. In our calculations the phonon modes of LA and LO at X point have been evaluated in frozen phonon approximation. We have obtained, at the same time, the LAX and LOX phonon frequencies for these materials from total energy calculations. The calculated phonon frequencies agree very well with experimental values for these semiconductors.
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Intervalley GAMMA-X deformation-potential constants (IVDP's) have been calculated by use of a first-principles pseudopotential method for the III-V zinc-blende semiconductors AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb. When the calculated IVDP's of LA phonons for GaP, InP, and InAs and of LO phonons for AlAs, AlSb, GaAs, GaSb, and InSb are compared with results of a previous calculation that used the empirical pseudopotential method (EPM) and a rigid-ion approximation, good agreement is found. However, our ab initio pseudopotential results on IVDP's of LA phonons for AlAs, AlSb, GaAs, GaSb, and InSb and of LO phonons for GaP, InP, and InAs are about one order of magnitude smaller than those obtained by use of EPM calculations, indicating that the electron redistribution accompanying crystal-lattice deformation has a significant effect on GAMMA-X intervalley scattering for these phonon modes when the anions are being displaced. In our calculations the LA- and LO-phonon modes at the X point have been evaluated in the frozen-phonon approximation. We have also obtained the LAX- and LOX-phonon frequencies for these materials from total-energy calculations, which agree very well with experimental values for these semiconductors. We have also calculated GAMMA-X hole-phonon scattering matrix elements for the top valence bands in these nine semiconductors, from which the GAMMA-X IVDP's of the top valence bands for the longitudinal phonons and transverse phonons are evaluated, respectively.
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为探索土壤低浓度多环芳烃污染的生态毒性及其对土壤生物的致毒机理,本论文初步研究了菲、芘、荧蒽和苯并[a]芘等四种多环芳烃人工土壤污染在0.1mg.kg-1~10.0mg.kg-1浓度水平对赤子爱胜蚓(Eisenia fetida)产卵量、体重变化、排卵激素annetocin基因和翻译控制肿瘤蛋白(translationally controlled tumor protein, TCTP)转录水平的影响,发现在相同的低浓度水平下,只有苯并[a]芘对蚯蚓annetocin前体基因和TCTP基因的表达有显著影响,故其对生物体的生殖风险和致癌风险可能最大。另一方面,低浓度苯并[a]芘对蚯蚓体重和产茧量并无显著影响,这表明基因表达水平作为污染生态监测指标比宏观观测指标更灵敏。 为进一步研究土壤PAHs污染的生态毒性效应,在上述研究基础上,我们采用SSH-PCR的方法构建了人工土壤1.0mg.kg-1苯并[a]芘胁迫下的蚯蚓与对照组蚯蚓之间的消减cDNA文库,随机挑取上调文库301个克隆及下调文库283个克隆进行测序,与NCBI蛋白数据库比对结果表明,其中有391个克隆与已知的75种蛋白质基因显著匹配(期望值< 10-5),其余克隆匹配不显著(期望值> 10-5)或找不到匹配蛋白。显著匹配的基因序列包括:一相解毒酶细胞色素P450,二相解毒酶谷胱甘肽硫转移酶,蛋白质合成所需的核糖体蛋白亚基,参与新合成肽链折叠的热休克蛋白,线粒体基因组编码的呼吸链复合酶体亚基,过氧化物还原蛋白,铁蛋白,钙结合蛋白,半胱氨酸蛋白酶等。表明低浓度苯并[a]芘胁迫引起蚯蚓的生理变化是非常复杂的,涉及污染物降解与解毒、抗氧化保护、能量代谢、蛋白质合成、金属离子调节与蛋白质降解等过程。 Real-time PCR检测验证消减文库中部分差异基因对不同剂量BaP胁迫响应结果表明,各检验基因序列受1.0 mg∙kg-1 BaP 胁迫影响均与消减结果一致,且影响程度均高于0.1 mg∙kg-1浓度水平的BaP;其中,在0.1 mg∙kg-1 BaP胁迫下,过氧化物还原酶PRDX和类似Cyp2R1的P450基因表达未见明显变化。其余的HSP70、HSP90、rpL10、COXⅡ、SCBP、Ferritin等基因在0.1 mg∙kg-1 BaP胁迫组蚯蚓中均有检测到预期表达变化,说明虽然从消减文库中获得的基因在一定的污染物浓度范围内均表现浓度效应,但各个基因对污染物的响应浓度不尽相同。 Real-time PCR检测消减文库中部分差异基因对不同PAHs胁迫响应结果表明,1.0 mg∙kg-1 浓度水平的荧蒽、菲、芘和苯并[a]芘对差异表达基因的影响不尽相同,主要有以下三种情况:(1)广谱响应型:蚯蚓线粒体编码的亚基COXⅡ、可溶性钙结合蛋白、铁蛋白等基因对荧蒽、菲、芘及苯并[a]芘的胁迫均有相似的响应;(2)随芳烃环数而变化型:热休克蛋白HSP70和过氧化物还原酶PRDX表现出响应程度随胁迫多环芳烃的环数增加而提高的现象;(3)仅在苯并[a]芘中有响应型:核糖体蛋白亚基L10和细胞色素P450(类似Cyp2R1)基因,在1.0 mg∙kg-1浓度条件下,它们仅受BaP诱导表达,而芘、菲和荧蒽却没有显示诱导作用。 上述结果表明,在土壤中的低浓度的多环芳烃污染胁迫对蚯蚓的影响是多方面的,这些影响至少涉及能量代谢、污染物降解与解毒、蛋白质合成与修复、信号转导、细胞凋亡、排卵生殖、个体发育等多方面的生理功能。目前蚯蚓基因组还未有完整测序,本文论述的多个差异表达基因是首次在蚯蚓中发现的,这些新发现的基因序列在为低浓度PAHs的生态毒性机理研究提供依据的同时,也为以蚯蚓为模式生物的土壤污染生物监测提供了备选的生物分子标记。另一方面,由于蚯蚓基因组未完整测序,本研究构建的消减文库中仍不少未知功能基因,其功能与调控有待进一步研究。