258 resultados para Dimethyl oxalate


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The phase diagram of the dodecyl dimethyl ammonium hydroxyl propyl sulfonate(DDAHPS)/1-pentanol(C5H11OH)/water ternary system has been established. It contains two isotropic monophase regions (L-1 and L-2) and a liquid crystalline region (L.C.). The isotropic phase regions have been investigated by means of Raman spectroscopy and conductivity.

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The phase behavior of liquid crystalline in the ternary system of dodecyl dimethyl ammonium hydroxyl propyl sulfonate(DDAHPS)/1-pentanol(C5H11OH)/water deuteron (D2O) has been investigated by polarizing optical microscopy, H-2 NMR spectroscopy methods. The results indicate that two kinds of liquid crystals (the lamellar, and the hexagonal) exist in the liquid crystalline phase region. In this paper, we also use the polarized Raman spectroscopy method to measure the values of the order/disorder parameters and the values of the environment polarity parameters for the samples selected from the liquid crystalline phase region, and compare these two parameters of the samples with those of solid state DDAHPS and liquid state pentan-1-ol.

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An optimal feedback control of two-photon fluorescence in the ethanol solution of 4-dicyanomethylene-2-methyl-6-p-dimethyl-amiiiostryryl-4H-pyran (DCM) using pulse-shaping technique based on genetic algorithm is demonstrated experimentally. The two-photon fluorescence of the DCM ethanol solution is enhanced in intensity of about 23%. The second harmonic generation frequency-resolved optical gating (SHG-FROG) trace indicates that the effective population transfer arises from the positively chirped pulse. The experimental results appear the potential applications of coherent control to the complicated molecular system.

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采用PEG/DMSO融合法,从普通烟草(Nicotiana tabacum L.cv.Xanthi nc)叶肉和毛曼陀罗(Datura innoxia Mill.)茎或叶愈伤组织原生质体融合获得I5株花盆中健康生长的族间体细胞杂种植株;其中11株是在没有选择压力的条件下获得,4株则是在有IOA和R6G选择系统存在下获得。同时获得一株试管开花且形态异常的植株和一株花盆中生长的嵌合植株。lOmM IOA和I5μ g/ml R6G均能分别有效地抑制烟草叶肉和毛曼陀罗愈伤组织原生质体的分裂;10% DMSO能显著提高原生质体融合率;PEG种类并不重要,但浓度则很重要;BAP较ZT,KT对植株分化有更好的诱导效果。杂种的形态、细胞、同工酶、Southern杂交,花粉育性分析结果如下:1、l5株杂种较双亲普遍株型矮小,生长缓慢,形态接近烟草但不很正常,根据形态特征可分为两种类型:(1)共有8株,其叶片大小、形状、颜色、开花习惯、花类型(单花)等均与毛曼陀罗接近,但子房败育;(2)共有7株,其株型、叶片形状、颜色、光滑度、花形状、类型(圆锥状花序)、颜色更接近烟草,但少数杂种开单花或先单花后圆锥状花序或先单花后两种花并存,且开花时间不一,部分子房败育。2、杂种染色体数目大都在60~90之间,个别者较少(48条)或较多(125条),没有一株为双二倍体(2n=96),并全部为混倍体。3、15株杂种植株均有双亲的细胞色素氧化酶同工酶特征谱带;大部分都有双亲的过氧化物酶同工酶特征谱带,少都仅具烟草的谱带。4、Hae Ⅲ/水稻rDNA的Southern杂交分析表明杂种1较双亲多一条谱带,杂种2较双亲也多一条弱带,其它杂种尚待定。5、花粉活力测定表明毛曼陀罗(种子再生而来)的为99%,烟草(原生质体再生而来)为80~90%,而杂种的为24~61%,育性普遍低于双亲。

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从山竺(Garcinia mangostana)果壳中分离得到6个化合物,通过MS,1D 1NMR以及与文献对照鉴定它们为4个(口山)酮类化合物:α-mangostin(1),β-mangostin(2),γ-mangostin(3),5,9-dihydroxy-8-methoxy-2,2-dimethyl-7-(3-methylbut-2-enyl)-2H,6H-pyrano-[3,2-b]-xanthen-6-one(4),以及表儿茶素(epicatechin,5)和一个双苄类化合物egonol(6).其中化合物5和化合物6为首次从该植物中分离得到.对化合物1~5进行抗HIV-1 RT活性筛选结果表明,化合物2和化合物5在浓度200 μg/ml的条件下,其对HIV-1 RT抑制率分别为41.97%和47.72%;同一实验结果显示化合物1,3和4没有抑制HIV-1 RT作用.

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The cryoprotective effects of 11 different extenders, TTE, DM, mDM, LG-DM, G-DM, TCG, TEST, TSM, Test-M, Test-H, and LM, on sperm cryopreservation of cynomolgus monkey (Macaca fascicularis) have been compared with glycerol as cryoprotectant. Sperm motility, plasma membrane, and acrosomal integrity were examined to evaluate frozen-thawed sperm function. The results showed that TTE, DM, mDM, LG-DM, G-DM, and TCG exhibited the best and similar protective efficiencies for cynomolgus monkey sperm cryopreservation in terms of sperm motility and plasma membrane integrity (P > .05). The acrosomal integrity for spermatozoa cryopreserved in TCG was statistically lower than that of TTE, DM, mDM, LG-DM, and G-DM (P < .05) but was significantly higher than that of TEST, TSM, Test-M, Test-H, and LM (P < .05). The postthaw sperm motility for 5 other extenders (TEST, TSM, Test-M, Test-H, and LIVI) did not exceed 30%, and the 3 sperm parameters evaluated for them were significantly lower than that of TTE, DM, mDM, LG-DM, G-DM, and TCG (P < .05). On the basis of these findings, 5 commonly used permeating cryoprotectants, glycerol, ethylene glycol, dimethyl sulfoxide, acetamide and propylene glycol have further been tested for their effectiveness on sperm cryopreservation in extenders of TTE, DM, mDM, LG-DM, G-DM, and TCG. The results showed that the sperm cryoprotective efficiencies of glycerol and ethylene glycol were similar and best among 5 permeating cryoprotectant treatments (P > .05). Dimethyl sulfoxide or acetamide resulted in average cryoprotection for cynomolgus monkey spermatozoa: poorer than glycerol or ethylene glycol but better than that of propylene glycol (P < .05). In addition, the action of permeating cryoprotectant appeared to be independent of extenders. The results in the present study demonstrate that 1) TTE, DM, mDM, LG-DM, G-DM, and TCG are excellent extenders and suitable for cynomolgus monkey sperm cryopreservation; 2) the mechanism of action of permeating cryoprotectants are not affected by extender composition; 3) ethylene glycol has a similar cryoprotective efficacy to glycerol that makes it a successful cryoprotectant for sperm cryopreservation in cynomolgus monkeys.

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Background: The anti-HIV-1 neutralizing antibody assay is widely used in AIDS vaccine research and other experimental and clinical studies. The vital dye staining method applied in the detection of anti-HIV-1 neutralizing antibody has been used in many laboratories. However, the unknown factor(s) in sera or plasma affected cell growth and caused protection when the tested sera or plasma was continuously maintained in cell culture. In addition, the poor solubility of neutral red in medium (such as RPMI-1640) also limited the use of this assay. Methods: In this study, human T cell line C8166 was used as host cells, and 3-(4,5-Dimethyl-2-thiazolyl)- 2,5-diphenyl-2H-tetrazolium bromide (MTT) instead of neutral red was used as vital dye. In order to avoid the effect of the unknown factor( s), the tested sera or plasma was removed by a washout procedure after initial 3 - 6 h culture in the assay. Result: This new assay eliminated the effect of the tested sera or plasma on cell growth, improved the reliability of detection of anti-HIV-1 neutralizing antibody, and showed excellent agreement with the p24 antigen method. Conclusion: The results suggest that the improved assay is relatively simple, highly duplicable, cost-effective, and well reliable for evaluating anti-HIV-1 neutralizing antibodies from sera or plasma.

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Isolation of high neutral lipid-containing microalgae is key to the commercial success of microalgae-based biofuel production. The Nile red fluorescence method has been successfully applied to the determination of lipids in certain microalgae, but has been unsuccessful in many others, particularly those with thick, rigid cell walls that prevent the penetration of the fluorescence dye. The conventional "one sample at a time" method was also time-consuming. In this study, the solvent dimethyl sulfoxide (DMSO) was introduced to microalgal samples as the stain carrier at an elevated temperature. The cellular neutral lipids were determined and quantified using a 96-well plate on a fluorescence spectrophotometer with an excitation wavelength of 530 nm and an emission wavelength of 575 run. An optimized procedure yielded a high correlation coefficient (R-2 = 0.998) with the lipid standard triolein and repeated measurements of replicates. Application of the improved method to several green algal strains gave very reproducible results with relative standard errors of 8.5%, 3.9% and 8.6%, 4.5% for repeatability and reproducibility at two concentration levels (2.0 mu g/mL and 20 mu g/mL), respectively. Moreover, the detection and quantification limits of the improved Nile red staining method were 0.8 mu g/mL and 2.0 mu g/mL for the neutral lipid standard triolein, respectively. The modified method and a conventional gravimetric determination method provided similar results on replicate samples. The 96-well plate-based Nile red method can be used as a high throughput technique for rapid screening of a broader spectrum of naturally-occurring and genetically-modified algal strains and mutants for high neutral lipid/oil production. (C) 2009 Published by Elsevier B.V.

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Kaolinite is a dominant clay mineral in the soils in tropical and Subtropical regions, and its dissolution has an influence on a variety of soil properties. In this work, kaolinite dissolution induced by three kinds of low-molecular-weight organic acid, i.e., citric, oxalic, and malic acids, was evaluated under far-from-equilibrium conditions. The rates of kaolinite dissolution depended on the kind and concentration of organic acids, with the sequence R-oxalate > R-citrate > R-malate. Chemical calculation showed the change in concentration of organic ligand relative to change in concentration of organic acid in suspensions of kaolinite and organic acid. The effect of organic acid on kaolinite dissolution was modeled by species of organic anionic ligand. For oxalic acid, L-oxalic(2-) and HLoxalic- jointly enhanced the dissolution of kaolinite, but for malic and citric acids, HLmalic- and H2Lcitric- made a higher contribution to the total dissolution rate of kaolinite than L-malic(2-) and L-citric(3-), respectively. For oxalic acid, the proposed model was R-Si = 1.89 x 10(-12) x [(25x)/(1+25x)] + 1.93 x 10(-12) x [(1990x(1))/(1+1990x(1))] (R-2 = 0.9763), where x and x(1) denote the concentrations of HLoxalic and L-oxalic, respectively, and x(1) = 10(-3.81) x x/[H+]. For malic acid, the model was R-Si =4.79 x 10(-12) x [(328-v)/(1+328x)] + 1.67 x 10(-13) x [(1149x(1))/(1+1149x(1))] (R-2 =0.9452), where x and x(1) denote the concentrations of HLmalic and L-malic, respectively, and x(1) = 10(-5.11) x x/[H+], and for citric acid, the model was R-Si = 4.73 x 10(-12) x [(845x)/(1+845x)] +4.68 x 10(-12) x [(2855x(1))/(1+2855x(1))] (R-2 =0.9682), where x and x(1) denote the concentrations of H2Lcitric and L-citric, respectively, and x(1) = 10(-11.16) x x/[H+](2). (c) 2005 Elsevier Inc. All rights reserved.

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化石燃料的不可再生性决定了其不能长久为全球经济和科技的发展提供能源动力,从可持续发展和能源战略的角度考虑,能够替代石油及其衍生品的清洁替代燃料研究已经成为提高能源供应安全、改善环境污染问题、应对气候变化的重要措施,对替代燃料的研究和应用已经成为各方关注和开发的热点。 二甲醚(DME、CH3OCH3)是一种最简单的醚类,它不含C-C健,可以由天然气、煤、生物质燃料等大量制备,而且具有较高的辛烷值(55-60),较低的碳氢化合物、CO排放,没有PM排放,因而被认为是一种非常有发展前景的发动机替代燃料,已经受到了广泛的关注。但是,在发动机燃用DME的实验研究表明,在其排气中有非常规污染物甲醛(HCHO)、乙醛(CH3CHO),甲酸甲酯(HCOOCH3)等排放,这些有机污染物会对环境和人类健康产生严重的危害,在环保要求日益严格的趋势下,这就制约了二甲醚的规模化应用。因此,对二甲醚燃烧性能、氧化中间产物甲醛等的产生和排放机理、相关污染物抑制技术需要进行着重研究,这对二甲醚燃料规模化应用、相关二甲醚燃烧器设计、燃烧性能的优化以及污染物控制技术的研究等都有着重要的理论指导意义和参考价值。 为了充分理解二甲醚燃料的燃烧特性、非常规污染物甲醛的产生和消耗机理,本文以实验和二甲醚化学反应动力学机理为指导,对二甲醚预混燃烧的燃烧特性、相关污染物和甲醛产生和消耗的机理做了详细的研究;并针对二甲醚燃料的不同应用背景,对二甲醚燃料低温下的氧化和甲醛生成特性、DME与LPG掺混燃烧特性和甲醛生成消耗机理进行了深入的研究,具体工作有: 研究了二甲醚预混燃烧特性、火焰中甲醛等污染物的产生特性,建立了火焰中甲醛取样、测量的方法和实验平台。并对当量比和燃料流量对二甲醚预混燃烧的燃烧特性、甲醛生成特性影响进行了考察,实验结果表明二甲醚是一种优良的替代燃料,在二甲醚火焰中甲醛是其重要的中间产物,甲醛浓度分布与当量比和预混气流速密切相关。当量比一定时,随着预混气流速的增加,火焰中甲醛产生的范围变窄,且甲醛浓度峰值逐渐移向燃烧器出口,而甲醛产生的浓度峰值数值上相差不大,甲醛在形成峰值后被快速消耗,其浓度在0.1mm内下降到几乎为零;在二甲醚流量一定时,随着当量比的增加,火焰中产生了更多的甲醛,火焰中甲醛分布的范围也变宽,而且当量比越大,甲醛的消耗也变缓,在当量比为0.8时,甲醛浓度从峰值到被消耗距离变为2mm,远大于当量比0.6和0.7下0.1mm的消耗距离。 对二甲醚预混燃烧进行数值研究和化学动力反应机理分析后发现,在二甲醚燃烧中,二甲醚的氧化反应途径主要是通过脱氢生成CH3OCH2和在高温下的直接裂解反应而进行,其中脱氢反应是低温下二甲醚消耗的主要途径,而在高温反应阶段(T>1000K),DME的直接裂解和燃料的脱氢反应共同起主导作用;非常规污染物甲醛通过DME脱氢产物CH3OCH2的裂解和外部氧化而生成,在高温时通过DME直接裂解后被氧化产生;甲醛的消耗反应则是通过与H、O、OH和CH3基的氧化反应而完成,其中与O、OH基的反应在燃烧中起主要作用。因此二甲醚燃烧中甲醛的抑制关键在燃烧中甲醛的消耗阶段,采取有效的技术措施,如优化燃烧器结构提高二甲醚燃烧室内的温度、在燃烧区保证充足的氧气供应等措施,加快甲醛的消耗速度以促进其被完全氧化,可以实现二甲醚燃烧中甲醛的零排放。 针对柴油发动机燃用DME燃料时,燃料在燃烧室停留时间过短,造成部分未燃二甲醚随尾气排放,对DME在低温下(<800K)的氧化特性和甲醛生成特性进行了实验研究。结果表明,二甲醚在200℃左右就开始发生氧化反应,在200~400℃温度范围内被氧化而生成大量中间产物甲醛,且在此温度范围内甲醛不易被氧化分解,而发动机尾气温度(一般在200~600℃之间)处于甲醛最易生成的范围,因此未燃二甲醚在尾气中发生低温氧化反应生成的甲醛,是发动机燃用DME而排放高浓度甲醛的重要来源。研究结论为柴油发动机燃用DME抑制非常规污染物甲醛的排放提供了新的参考。 DME作为替代燃料,部分替代及与其他石化系燃料掺混燃烧是目前的重要应用方向,对DME与LPG掺混燃烧特性和甲醛生成特性进行了实验研究,结果表明,在DME与LPG掺混燃烧中,固定当量比和燃料质量流量的条件下,两种燃料存在一个最佳掺混比,在此掺混比例下,混合燃料着火提前,燃料燃烧性能最佳;DME与LPG混合燃料中,二甲醚是燃烧中甲醛产生的主要来源,控制DME的完全氧化和燃烧是抑制DME与LPG掺混燃烧排放甲醛的主要途径,这为更好地应用DME与LPG混合燃料提供了参考。 能否清洁高效燃烧是决定替代燃料DME应用规模和途径中的关键任务,本文对DME燃烧特性、非常规污染物甲醛的生成排放特性、低温下DME的氧化特性、DME与LPG掺混燃烧特性的研究,从不用的应用方向和领域对DME清洁高效燃烧进行了探讨和研究,研究成果可以为清洁高效利用二甲醚、抑制甲醛排放,以及开发相关燃烧技术、燃烧器提供实验依据和理论指导。本文在DME燃烧特性和非常规污染物甲醛的产生与排放方面取得了具有创新性的研究结果。

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With naphthalene as biomass tar model compound, partial oxidation reforming (with addition of O-2) and dry reforming of biomass fuel gas were investigated over nickel-based monoliths at the same conditions. The results showed that both processes had excellent performance in upgrading biomass raw fuel gas. Above 99% of naphthalene was converted into synthesis gases (H-2+CO). About 2.8 wt% of coke deposition was detected on the catalyst surface for dry reforming process at 750 degrees C during 108 h lifetime test. However, no Coke deposition was detected for partial oxidation reforming process, which indicated that addition of O-2 can effectively prohibit the coke formation. O-2 Can also increase the CH4 conversion and H-2/CO ratio of the producer gas. The average conversion of CH4 in dry and partial oxidation reforming process was 92% and 95%, respectively. The average H-2/CO ratio increased from 0.95 to 1.1 with the addition of O-2, which was suitable to be used as synthesis gas for dimethyl ether (DME) synthesis.

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A promising application for biomass is liquid fuel synthesis, such as methanol or dimethyl ether (DME). Previous studies have studied syngas production from biomass-derived char, oil and gas. This study intends to explore the technology of syngas production from direct biomass gasification, which may be more economically viable. The ratio of H-2/CO is an important factor that affects the performance of this process. In this study, the characteristics of biomass gasification gas, such as H-2/CO and tar yield, as well as its potential for liquid fuel synthesis is explored. A fluidized bed gasifier and a downstream fixed bed are employed as the reactors. Two kinds of catalysts: dolomite and nickel based catalyst are applied, and they are used in the fluidized bed and fixed bed, respectively. The gasifying agent used is an air-steam mixture. The main variables studied are temperature and weight hourly space velocity in the fixed bed reactor. Over the ranges of operating conditions examined, the maximum H-2 content reaches 52.47 vol%, while the ratio of H-2/CO varies between 1.87 and 4.45. The results indicate that an appropriate temperature (750 degrees C for the current study) and more catalyst are favorable for getting a higher H-2/CO ratio. Using a simple first order kinetic model for the overall tar removal reaction, the apparent activation energies and pre-exponential factors are obtained for nickel based catalysts. The results indicate that biomass gasification gas has great potential for liquid fuel synthesis after further processing.

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A liquid laser medium with a lifetime of 492 mu s and a fluorescent quantum efficiency of 52.5% has been presented by stably dispersing dimethyl dichorosilane-modified Nd2O3 nanoparticles in dimethylsulfoxide. Its optical properties and mechanism were investigated and explained by fluorescence resonance energy transfer theory. The calculation result shows that the quenching of Nd-III F-4(3/2)-> I-4(11/2) transition via O-H vibrational excitation can be eventually neglected. The main reason is that the silane-coupling agent molecules remove the -OH groups on Nd2O3 nanoparticles and form a protective out layer. (c) 2007 American Institute of Physics.

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Two photochromic fulgides, 2-{2-[4-(N,N-dimethylnilino)-5-methyl-4-oxazoly]}ethylidene-4-(1-methylethylidene) tetrahydrofuran-2,5-dione (A) and 3-(1,2-dimethyl-5-phenyl-3-pyrolloethylidene)-4-(1-methylethylidene)tetrahydrofuran-2,5-dione (B), doped in PMMA as candidates of dual-wavelength optical memory for parallel recording has been investigated. With 488 nm-laser and 650 nm-laser, both "cross" and "star" images are recorded on the fulgides-PMMA film and read out clearly, respectively. Crosstalk between two fulgides in PMMA matrix and nondestructive readout has also been explored. The results show that no significant cross-talk is detected between them, and nondestructive readout is up to 201 times. (C) 2005 Elsevier B.V. All rights reserved.