13 resultados para Meningite bacteriana. APE1. Citocinas. Vitamina B6

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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The stress release model, a stochastic version of the elastic rebound theory, is applied to the large events from four synthetic earthquake catalogs generated by models with various levels of disorder in distribution of fault zone strength (Ben-Zion, 1996) They include models with uniform properties (U), a Parkfield-type asperity (A), fractal brittle properties (F), and multi-size-scale heterogeneities (M). The results show that the degree of regularity or predictability in the assumed fault properties, based on both the Akaike information criterion and simulations, follows the order U, F, A, and M, which is in good agreement with that obtained by pattern recognition techniques applied to the full set of synthetic data. Data simulated from the best fitting stress release models reproduce, both visually and in distributional terms, the main features of the original catalogs. The differences in character and the quality of prediction between the four cases are shown to be dependent on two main aspects: the parameter controlling the sensitivity to departures from the mean stress level and the frequency-magnitude distribution, which differs substantially between the four cases. In particular, it is shown that the predictability of the data is strongly affected by the form of frequency-magnitude distribution, being greatly reduced if a pure Gutenburg-Richter form is assumed to hold out to high magnitudes.

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细胞色素b6f蛋白复合体(Cyt b6f)是光合链中连接两个光系统(PSII 和PSI)的中间电子载体蛋白复合物,其主要的生理功能是催化电子传递和质子跨膜转移,形成跨膜质子电化学梯度,为ATP的合成提供能量,在光合作用光能转化过程中占有很重要的地位。细菌和莱茵衣藻Cyt b6f的晶体结构已于2003年底获得了近原子水平的解析,但有关该复合物中两种色素(Chl a和β-Car)的生理功能及其机理尚无明确的解释。预计它们将成为今后几年的研究热点,因为揭示Cyt b6f蛋白复合体中Chl a和β-Car分子的生理功能对于进一步阐明光合作用高效转能及其调控的分子机理具十分重要的意义。鉴于目前尚未见到海洋绿藻Cyt b6f的报道,本文以海洋绿藻—假根羽藻(Bryopsis corticulans)类囊体膜上的Cyt b6f蛋白复合体为对象,对其中的类胡萝卜素的分子结构与生理功能进行了比较系统地研究。 首先,我们改进了原用于菠菜类囊体膜Cyt b6f的分离、纯化流程,在原流程的基础上增加了一次2 mol/L NaBr洗膜,彻底地去除了膜表面的杂蛋白;还调整了第二次硫酸铵分级沉淀时的饱和度,并将38-45%饱和度下的沉淀物确定为需要收集的Cyt b6f制剂。采用此改进的流程,我们首次从假根羽藻类囊体膜中分离纯化了高活性、高纯度的Cyt b6f制剂。SDS-PAGE分析的结果显示该制剂的4个多肽亚基 (Cytf 、Cyt b6 、Rieske[Fe-s]及亚基IV)的表观分子量分别为34.8、24.0、18.7和16.7 kD;Cyt b6 / f 比值接近2.0, 其纯度值为9.9 nmol cyt f/mg;其催化电子传递的活性 (C10-PQH2→PC)为73 e/s。HPLC 和共振拉曼光谱分析表明,假根羽藻Cyt b6f中的类胡萝卜素为α-胡萝卜素分子,它是一种在Cyt b6f中尚未报道过的类胡萝卜素。定量分析表明,每个假根羽藻Cyt b6f单体中全反式(all-trans)和9顺式(9-cis)α-胡萝卜素的含量分别为0.2和0.7个分子,另外还含有1.2分子的Chl a。CD光谱分析表明该9-cis-α-胡萝卜素处在一个不对称的蛋白环境中。TLC分析表明该制剂是一种缺脂的Cyt b6f蛋白复合体。 采用稳态荧光激发光谱,时间分辨吸收光谱及Chl a的光破坏实验对假根羽藻Cyt b6f中α-胡萝卜素的功能进行了研究。结果表明,Cyt b6f中α-胡萝卜素可以将它吸收的光能传递给Chl a,其能量传递效率为62.4%,提出α-胡萝卜素分子与Chl a分子之间的单线态能量传递是遵从Föster 机制进行的;α-胡萝卜素分子对Chl a分子有一定的光保护作用,这种保护作用是通过清除单线态氧来实现的。另外还发现Cyt b6f中的Chl a分子可能与其周围的氨基酸残基存在相互作用,认为这是其进行自我光保护的一种方式。 此外,还采用HPLC研究了光和暗交替对假根羽藻Cyt b6f中α-胡萝卜素构型的影响,并对假根羽藻Cyt b6f选择结合α-胡萝卜素的原因进行了初步的分析。

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细胞色素b6f蛋白复合体(Cytochrome b6f complex, Cyt b6f)是光合膜上参与光合作用原初反应过程的主要膜蛋白超分子复合体之一。莱茵衣藻和嗜热蓝细菌的Cyt b6f三维晶体结构均显示,每Cyt b6f单体分子含有1分子Chlorophyll a (Chl a ),充分肯定了Chl a 是Cyt b6f天然成分的观点(Kurisu et al,2003;Stroebel et al,2003)。研究表明不同来源的Cyt b6f中Chla单线激发态寿命(或荧光寿命)并不一样,多数的研究结果认为Cyt b6f中Chla单线激发态寿命只有200ps左右,但是也有Cyt b6f中Chla单线激发态寿命为~600ps的报道;而甲醇中游离Chl a 的单线激发态寿命为4ns左右。针对Cyt b6f中Chla单线激发态寿命快速淬灭的现象,Dashdorj 等(2005)根据晶体结构推测Cyt b6f中Chla单线激发态和邻近的Cyt b6亚基上Tyr105残基发生电子交换传递,从而快速淬灭Chla单线激发态,减少了三线态Chl a和单线态氧的产生,并且认为这是Cyt b6f保护自身不受单线态氧破坏的一种机制,但是这一推测缺乏有力的证据。另外,Cyt b6f中Chla的功能仍然未知。本文以菠菜Cyt b6f为对象,结合多种实验手段,测定了菠菜Cyt b6f中Chl a单线激发态寿命,并对复合体中Chl a 单线激发态淬灭的机理进行了深入研究。此外,我们还对复合体中Chl a 可能的功能进行了初步地探讨。获得了如下的结果: 1.针对不同来源的Cyt b6f中Chla单线激发态寿命(或荧光寿命)测定结果不同的报道,仔细分析了其中的原因,发现除了样品来源的差异外,使用不同的去垢剂可能是一个不可忽视的因素。在实验中,不同的研究者分别采用了十二烷基麦芽糖苷(n-Dodecyl β-D-maltoside,DDM,)和八烷基葡萄糖苷(n-Octyl β-D-glucopyranoside,β-OG)作为溶解样品的去垢剂。因此,本文借助稳态吸收和稳态荧光光谱、瞬态光散射技术,CD光谱和亚皮秒时间分辨吸收光谱等技术,分别研究了这两种去垢剂对Cyt b6f结构和功能的不同影响。结果表明,DDM去垢剂能使Cyt b6f处于较好的分散体系中,其中血红素和Chl a分子处于特定的蛋白环境中,不会导致Cyt b6f变性;而β-OG去垢剂会使Cyt b6f产生聚合现象,其中的血红素和Chl a与蛋白环境的相互作用减弱,和DDM相比其电子传递活性显著降低,Chl a单线激发态寿命延长,Chl a更容易被光破坏。通过这一工作,我们优化和确定了Cyt b6f的溶解条件,为下面的研究工作打下了良好的基础。 2.利用Tyr的特异性修饰剂p-Nitrobenzenesulfonyl Fluoride(NBSF)对Cyt b6f样品进行特性修饰,经原子吸收谱、荧光谱、CD谱、质谱等方法对修饰后的样品进行鉴定,并结合时间分辨飞秒吸收光谱技术,测得修饰后的样品在660nm激发下Chl a 单线激发态寿命延长,从而在实验上提供了Tyr与淬灭Chla单线激发态有关的证据。但是对Cyt b6f 中Chl a瞬态吸收图谱仔细研究表明,菠菜Cyt b6f 中Chl a单线激发态快速淬灭过程中并没有发现Tyr与Chl a 之间发生电子传递时所形成的Chla•¯。以上结果表明,Cyt b6f 中Chl a单线激发态快速的淬灭确实和邻近的Tyr105有关,但是与Dashdorj 等提出的Chla单线激发态和Tyr105残基发生了电子交换传递从而淬灭Chla单线激发态这一想法不符,关于这一问题值得进一步深入研究。 3.红光和绿光对Cyt b6f 照射,Cyt f可以被还原,并且红光比绿光更容易使Cyt f 还原,暗示Cyt f 的还原与Chl a 的关系密切,有可能是Chl a 被激发后,其被激发的电子传给Cyt f。对这一现象的进一步研究表明,Cyt b6f在光照条件下,Cyt f 的还原与体系内C10-PQ库的氧化还原状况相关,氧化型的C10-PQ可能介导电子从Chla传向Cyt f。由于在体内质体醌库的氧化还原状态往往决定Cyt b6f 的氧化还原状态,而通过对Cyt b6f不同氧化和还原状态的吸收谱和荧光谱的研究表明,氧化态和还原态的Cyt b6f 中,Chl a 与蛋白的结合状态是有差异的。这些差异可能暗示着Chl a 分子在行使其功能时与复合体的氧化还原状态是有关系的。通过以上的结果,对Cyt b6f中Chl a 可能的功能进行了假设。 4.此外,我们还发现Cyt b6f具有明显的过氧化物酶活性。在0.1 mmol/L乙酸钠缓冲液,pH3.6,25℃,[H2O2] <40mmol/L的条件下,其催化反应的速度常数为kobs=26±1.2M•s-1;对H2O2的Km 值为50mmol/L,对guaiacol的Km 值为2mmol/L;反应的最适pH为3.6,最适离子强度为0.1,最适温度为35℃。推测Cyt b6f的这种过氧化物酶活性可能是在胁迫环境下使Cyt b6f中的血红素和Chl a 分子免受H2O2的破坏。

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国家攀登B计划(PD- B6 - 7 - 3);国家自然科学基金(39430102 号);国家九五攻关计划(96 - 922 - 02

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In most parts of China, mosquitoes have been subjected to organophosphate (OP) insecticide treatments since the mid-1960s, and resistance gene monitoring in the Culex pipiens complex (Diptera: Culicidae) started in only a few locations from the end of the 1980s. Many resistant alleles at the Ester locus have been found in field populations, including those commonly found around the world (Ester(B1) and Ester(2)), and those endemic to China (Ester(B6), Ester(B7), Ester(8), and Ester(9)). This situation is atypical, and may represent a complex situation for the evolution of insecticide resistance genes in China. To increase our understanding of the Chinese situation and our ability to manage resistance in the C. pipiens complex, a large study was performed. Twenty field populations were sampled from Beijing to Guangzhou. Bioassays with five insecticides (dichlorvos, parathion, chlorpyrifos, 2-sec-butylphenyl methyl carbamate, and propoxur) disclosed resistance levels variable according to the geographic origin, and up to 85-fold for dichlorvos. Six overproduced esterases were identified, including two that have not been previously described. Most of them were found in all samples, although at variable frequencies, suggesting variable selection or a transient situation, e.g., each one was recently restricted to a particular geographic area. The results are discussed in the context of recent alterations to insecticide campaigns, and of the evolution of resistance genes in Chinese C. pipiens populations.

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维生素(Vitamin)又称维他命,为“万年青”产品,是维持人体生命健康必需的一类低分子有机化合物质。维生素对人体健康的作用人们研究很多, 维生素可以增强人体对感染的抵抗力,降低出生缺陷及降低癌症和心脏病发病率等,一旦缺乏,肌体代谢就会失去平衡,免疫力下降,各种疾病,病毒就会趁虚而入;而维生素对作物影响的研究却很少。目前为止,尚无对用维生素浸种的方法来研究外源维生素是否对小麦种子萌发及幼苗生长起调节作用的报道,且对其在小麦抗逆性方面影响的研究甚少,对盐的胁迫抗性研究尚未有人报道。小麦(Triticum aestivum L.)属于拒盐的淡土性作物。盐害不利于小麦生长,严重影响小麦的产量和品质。本研究采用4 种不同维生素VB1、VC、VB6、VPP,分别对供试小麦品种川育12(红皮)、川育16(白皮)小麦浸种后,在一般自然条件下和逆境(盐胁迫条件)下,进行试验。探讨在正常情况下与在不同盐浓度条件下,各维生素及盐浓度对小麦发芽及幼苗生长的影响,并且比较两种不同皮色的小麦在相同盐胁迫条件下的差异表现,同时研究维生素处理的特异性,且哪种维生素对盐害缓解作用最佳。研究结果表明:在无盐胁迫(自然)条件下,对用4 种不同维生素VB1、VC、VB6、VPP 浸种小麦川育12、川育16 后的种子萌发及幼苗生长(幼苗的根长、根重、苗高、苗鲜重)的研究结果表明:4 种外源维生素浸种均对小麦发芽有调节作用,都能提高其最终发芽率。但是提高幅度有所差异。用VB6 浸种后的小麦提高幅度最多,VC 次之,VPP 提高幅度最小。同时,4 种外源维生素浸种对小麦种子的出芽速度及芽后长势也有一定的影响。VB6、VC 处理的小麦种子出芽速度最快,萌发后长势最好;VB1 出芽速度相对较慢,VPP 最慢,但都大于对照;VB1 处理长势略高于对照,VPP 处理的小麦长势则低于对照。从整体来看,VB6、VC处理促进效应明显, VB1 次之,而VPP 在某些方面无效甚至产生负效应。此外,相同的维生素处理对不同的品种的种子萌发、生长效果也存在差异,各种维生素作用于川育12 的效应均强于对川育16。进一步对幼苗根系TTC 还原力及幼苗叶片中硝酸还原酶活性进行测定、分析。研究发现:并非所有种类的维生素对幼苗根系TTC 还原力及幼苗叶片中硝酸还原酶活性的提高都有帮助。幼苗根系TTC 还原力在不同维生素处理下存在显著差异,而与小麦品种关系甚微。经VB6、VC 处理后,根系TTC 还原力测定值均显著高于对照,VB1 不明显,VPP 则略低于对照。VB6、VC 处理的幼苗叶片中硝酸还原酶的含量大于对照,VB1 与对照相差无几,而VPP 处理的川育12 幼苗叶片中的硝酸还原酶活性比对照CK 略高,而在川育16 中则略比对照CK 有所下降,呈现出抑制效应。综上结果表明:VB6、VC 具有促进种子发芽,幼苗生长及根系生长的作用,是较好的促生长剂;VPP 具有抑制作用,是较好的抑制剂,可进一步研究、开发利用。在盐胁迫条件下,对用4 种不同维生素VB1、VC、VB6、VPP 浸种川育12、川育16 后的种子萌发及幼苗生长(幼苗的根长、根重、苗高、苗鲜重)的研究结果表明:在不同盐浓度胁迫条件下, 各处理的种子萌发及幼苗生长均受到不同程度的抑制。随着盐浓度的增加, 发芽率、发芽指数和活力指数成下降趋势;幼苗的根长、根重、苗高、苗鲜重不断降低。4 种维生素处理间也表现出较大差异。VB6、VC 在每个处理中均保持对盐害的缓解作用,VB6 较VC 更易于促进发芽及幼苗生长。最终发芽率高,根系多、长、重,苗高高、重。而VB1、VPP 则表现出抑制作用。在高盐浓度150mM 时,4 种维生素浸种后的种子,其最终发芽率均不能达到40%,但VB6、VC 处理最终发芽率、苗重、根重均高于对照,VPP 最终发芽率、苗重、根重均低于对照。进一步对幼苗根系TTC 还原力及幼苗叶片中脯氨酸含量进行测定、分析。研究发现:不同盐浓度,不同维生素处理、不同品种间存在差异。随着盐浓度的增加(75mM,100mM,150mM),幼苗根系TTC 还原力活性成下降趋势,幼苗叶片中脯氨酸的积累量成上升趋势。VB6 处理脯氨酸含量增加最为明显,VC 次之,VPP 与对照接近,其变化幅度最小。经VB6、VC 处理后的幼苗根系还原强度,在不同盐浓度下,测定值均显著高于对照,VB1 不明显,VPP 则低于对照,产生负效应。此外,品种间表现不尽相同,相同的维生素处理,相同的盐浓度对不同的品种的种子萌发、生长效果也存在差异, 4 种维生素对川育16 的作用均强于川育12,但其影响趋势是一致的。说明VB6、VC 具有耐(抗)盐性,可以促进种子发芽和幼苗生长,是较好的耐(抗)盐拌种剂。 Vitamin is one kind of necessary low molecular compound for humans tosustain health and life. Lots of Studies have been done on the effectc of the vitaminsfor people. Vitamin can help people improve the body's natural resistance to disease,Drop the rate of birth defects、cacers and the incidence of the heart diseases. Ifpeople have less of them, the metabolism of the organism may throw off balance,immunity may drop off, and catch disease; Though the effects for Vitamin to thecrops are limited. up to now, there’s no one use soking seeds of wheats with vitaminsas a method, to study on how the effects will happen on the wheat seed germinationand seedling growth, and there are only few reserches on antireversion force forwheats ,none for the antireversion force in Sault stress condition.Wheat(Triticum aestivum L.)is sensitive to the salt, so the salt damage will doharm to wheat’s growth, it will have an unfavorable impact on the output and thequality of wheat.On this reaserch, we Soaking CHY12(red)、CHY16 (white) wheat seeds withVitamin C, B1, PP, B6 (50mg/L) as a pretreatment first. Then under two condition: one is in the normal environment the other is in different Salinity, we begin ourexperiments. Then disscuss on if the vitamin and salinity affect the wheat seedgermination and seedling growth, and what is the different between the two of them,the result shows that:Under the normal condition, after soaking seeds with VB1、VC、VB6、Vpp,we study on the their seed germination and the seeding growth(the root length andweights, The seedling heights and weights), it shows that all of those four kinds ofvitamin can adjust the seed germination, but different in The growth rate. VB6 isbest for increase, VC comes second,VPP is the worst. Meanwhile, those four vitaminalso have effect on the speed of the sprouting of the wheat. VB6、Vc can faster theseed germination most, and the seedlings are all doing well; VB1 do little effects onthe budding, Vpp is the worst, but all treatments are better than CK; but in Vi, VB1some what above the CK, while VPP lower than that. On the whole, the acceleratingeffect of VB6、VC are obvious, VB1 takes second place, but VPP in some aspects arenoneffective even have negative effect. Furthermore, different kind of seeds with thesame vitamin may different in seed germination and seedling growth, four vitaminson CHY16 is better than CHY12.More studies on TTC reductive capacity of roots and the activity of nitratereductase in the leaves, the reasult shows not all the vitamin can help the seedlings toimprove the TTC reductive capacity and the activity of nitrate reductase. TTCreductive capacity in different treatments shows significant differences,but notcorrelate to the variety of the wheat. The TTC reductive capacity of VB6、Vctreatments are all higher than CK, VB1 is nearly the same as CK, VPP is a littlelower than CK. Through the study of acivity of nitrate reductase, it shows that,VB6、VC are higher than CK ,VB1 is nearly the same as CK also, VPP is a little higher inthe CK of CHY12 but lower in CHY16. Through all the results above: VB6、Vc helpthe wheat seed germination, seedling growth and the growth of roots, is theperfectable factor of stimulating the growth; Vpp is a inhibition, that’ll be furtherreserch,and well develop and utilize in the future.Under the different Salinity condition, after soaking seeds with VB1、VC、VB6、Vpp,we study on the their seed germination and the seeding growth(the root lengthand weights, The seedling heights and weights), it shows that: under differentsalinity, the seed germination and the seedling growth of any treatment are inhibited.With the increase of the concentration, the germination rate, Vi、Gi all had fallen; theroot length and weight, the seedling heights and weights steadily sank down. There are also have pronounced difference between all treatments with four differentvitamins.VB6、VC in all treatments are alleviative the salt damage, VB6 is easier tocause to put forth buds than VC, and it’s quantitative value is the highest in theultimate germination rate, in root and seedlings’ hight and weight. Though the VPP、VB1 are seems to inhibite its growth. Under the high concentration150mM Nacl, theultimate germination rate in all treatments are below the 40%, but VB6、VC’squantitative values in any experiments are higher than CK,while VPP lower thanCK.Then we study on the TTC reductive capacity of roots and the content of Polinein leaves, the result shows that between the different salinity, different vitamintreatments, different varieties of the wheat have discrepancy.along with theincreasing concentraion of the salinity(75mM,100mM,150mM),TTC reductivecapacity of roots decreases, the accumulation of the content of Poline in leaves havean upward trend. The increase of VB6’s treatment are obviously, VC comessecond,VPP is nearly come up with CK, changes a little. In TTC reductive capacity of roots’s reserch, VB6、VC are higher than CK at any time,VB1 is not palpable,VPP is lower than CK, makes negative affect on wheat. In addition, varieties of thewheats are remain different, no matter it shows promoting or inhibiting, all fourvitamins have moreobvious effects on CHY16 than CHY12, but the tendency of theeffection are the same. It is say that VB6、VC can help wheat to standwith the saultwell, and promot in growth,they are the better reagent to mix with the seed.

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水稻化感品种能从根系分泌释放化感作用物质 ,长期以来 ,酚酸类物质被认为是水稻根分泌的主要化感物质 ,但这一结论常常被质疑。利用连续循环和直接树脂吸收两种方法采集典型的水稻化感品种 PI31 2 777幼苗的根分泌物 ,并用液相色谱 /质谱(L C/ MS)联用技术鉴定了根分泌物中的非酚酸类物质。结果显示 ,水稻 PI31 2 777幼苗根系能分泌释放 7-甲氧基羟基肟酸、羟基肟酸、3-异丙基 - 5 -乙酰氧基环己烯酮 - 1、5 ,7,4′-三羟基 - 3′,5′-二甲氧基黄酮、二萜内酯 A和二萜内酯 B6个非酚酸类化合物。经液相色谱 (HPL C)定量分析 ,这些化合物在水稻生长 1 0 d的根分泌物中的浓度为 5~ 1 9μmol/ L。进一步的生测结果显示 ,这些化合物在其释放的浓度范围能对稻田常见的稗草和异型莎草有抑制活性 ,尤其是这些化合物的等摩尔混合物的抑草活性增加 ,同时水稻根分泌物的抑草活性与土壤载体显著相关。表明羟基肟酸、环己烯酮、黄酮和二萜内酯四类非酚酸类物质是水稻的主要化感物质 ,这与近期愈来愈多的研究结果一致

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高温固相扩散方法首次合成了Zn4 B6 O1 3:Ce3+ ,Tb3+ 光致发光材料。通过XRD分析获得晶胞参数 :a =0 7472nm ,V =0 .4172nm3,为立方晶系。研究Ce3+ 和Ce3+ ,Tb3+ 在Zn4 B6 O1 3中的激发和发射光谱 ,发现Ce3+ 在Zn4 B6 O1 3中的激发和发射带比Ce3+ 在其他基质中红移2 3 8~ 4.94KK ,Ce3+ 的发射带与Tb3+ 的 7F6 → 5G2 ,5D1 ,5H7吸收带有很好的重叠 ,使Ce3+ 对Tb3+ 有良好的敏化作用。Ce3+ ,Tb3+ 在基质中的能量传递机理为 :Ce3+ →Ce3+ 和Ce3+ →Tb3+ 之间的偶极子—偶极子的电多级相互作用的共振传递机理。色坐标为 :x =0 2 81,y =0 .619。SEM摄取产物的晶貌 ,颗粒均匀 ,平均粒度为 0 .2 3 μm ,接近纳米级。

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Three novel series of monomers, namely n-1-bromo-[4-(4-methoxyphenylazo)phenyloxy]-alkanes (Bn, n = 3, 6, 10), n-[4-(4-methoxyphenylazo) phenyloxy]alkyloxy-4-methoxybenzene (Cn, n = 3, 6, 10) and n-[4-(4-methoxyphenylazo)phenyloxyl]alkyloxy-[4-methoxy-2,5-bis-(chloromethyl)] benzene (Dn, n = 3, 6, 10) were synthesized and characterized with FTIR, H-1 NMR, UV-visible and fluorescence spectroscopy. Their thermal behaviour was studied by different scanning calorimetry and polarizing optical microscopy. The results show that B3, B6 and C6 exhibit monotropic nematic liquid crystalline behaviour.

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用X射线座滴照像法测量了铝液-氟化物熔盐间的界面张力。采用曲线拟合液滴轮廓坐标的计算机程序处理座滴图像。用逐步回归分析方法获得了计算熔盐密度值的回归方程。讨论了熔盐中NaF/AlF_3分子比,Li_2CO_3和稀土氧化物含量对熔盐-铝液间界面张力的影响。测量了铝液在熔盐中对石墨、工业碳块以及TiB_2涂层的润湿角。