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1.
液晶态磷脂酰乙醇胺脂质体和LB膜结构的研究 总被引:10,自引:0,他引:10
用原子力显微镜、小角X射线散射和31PNMR分别对液晶态磷脂酰乙醇胺脂质体和LB膜结构进行了研究.用原子力显微镜观察到了液晶态脂质体的立方相和双层膜共存的结构图像.研究结果表明,两相共存的状态与双亲性分子的结构、浓度以及介质的组分和pH等因素有关.用小角X射线散射和31PNMR研究发现,在DEPE液晶态中,钠盐诱导形成Q229(Im3m)立方相.DEPE液晶态分别在37.5℃出现Lβ→Lα可逆相变,在63.5℃出现Lα→HⅡ可逆相变. 相似文献
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苯及其衍生物甲苯,一氯代苯都是重要的有机试剂和化工原料,也是对人体有害的有机物。为了了解这些有机试剂对处于生物液晶态的生物膜毒害的机理,我们以含水卵磷脂组成的液晶体系作为人工模型用小角X射线散射(SAXS)方法探讨这些有机试剂对它们结构的影响。关于苯或其它非极性有机介质与含水卵磷脂形成液晶体系及其结构模型前人有一些报导。 相似文献
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溶剂性质对层状液晶结构与稳定性的影响 总被引:3,自引:0,他引:3
郭荣 《高等学校化学学报》1991,12(11):1526-1528
水体系层状液晶虽早有研究,但对非水层状液晶的研究则开始较晚,本文用HNMR和小角X射线衍射等方法,研究了极性有机溶剂甲酰胺代替水后,对SDS/C10OH/溶剂体系层状液晶结构与稳定性的影响。 相似文献
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直链醇链长对层状液晶结构与稳定性的影响 总被引:8,自引:4,他引:8
作为助表面活性剂,直链醇在层状溶致液晶的制备中是非常重要的。本文以层状液晶的相行为和小角度X射线衍射测量,研究了直链醇链长对层状液晶结构与稳定的影响。 相似文献
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关于电解质溶液对卵磷脂液晶结构的影响前人有过报导。例如Chapman和G. Shiply等在研究碱金属氯化物对卵磷脂液晶结构的影响时指出:随着Li~ 到Cs~ 离子半径增加,脂双层的厚度也发生相应变化。Plainer等也指出KCI,NaCl溶液使磷脂层厚度发生变化。关于磷脂蛋白复合膜与Na~ ,K~ 、Ca~(2 )离子的作用也有一些报导。本文报导用小角X射线散射(SAXS)方法研究几种电解质溶液对卵磷脂形成液晶结构的影响。 相似文献
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NaCl、KCl、Na2CO3、K2CO3等电解质溶液对含水卵磷脂液晶结构影响的SAXS研究 总被引:1,自引:0,他引:1
This paper describs the structural character of liquid-crystal of 5%H_2O-egg yolk phospholipid (PC) containing in avarious salt's solution, the layer distance was determined by means of SAXS method. Experimental results show that the layer distance of liquid crystal phase is increased in the 5%H_2O-PC system as the amount of solution of NaCl or KCl is increased. But on the addition of Na_2CO_3 or K_2CO_3 solution into the 5%H_2O-PC system the layer distance of liquid-crystal phase is held constant. It is considered that Na_2CO_3 or K_2CO_3, might be hydrolyzed producing OH~- ions, so that the latter could stablize the interfacial potential between water and egg yolk phospholipid. Absence of this behavior for solution of NaCl or KCl might be due to NaCl and KCl are salts which formed by strong acids and strong bases. 相似文献
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糖和盐类物质对生物膜超分子结构稳定性影响的研究 总被引:1,自引:0,他引:1
用原子力显微镜(AFM)和小角X射线(SAXS)技术, 研究了NaCl、KCl、胆固醇、葡萄糖和蔗糖等与膜脂的相互作用. 研究发现它们能引起脂质膜超分子体系液晶态结构的变化. 葡萄糖和蔗糖对脂双层膜结构有稳定作用. 在NaCl溶液中制成的脂质膜, 随着NaCl浓度的增加, 它们的双层膜更稳定. 在KCl溶液中结果恰好相反. AFM研究发现液晶态脂双层膜结构与双亲性分子的结构、浓度以及介质的组分和pH等因素有关. 在1,2-反十八碳-3-磷脂酰乙醇胺(DEPE)液晶态中, 钠盐诱导形成Q229(Im3m)立方相. 油酸的含量对DEPE-PVP(聚乙烯吡咯烷酮)超分子结构也有一定的影响, 当油酸含量达到某一临界值时, 则发生从Im3m(Q229)到Pn3m(Q224)的转变. 胆固醇能促使形成Pn3m(Q224)和六角相HII共存相. 研究结果表明, 生物膜超分子聚集体的氢键、分子van der Waals力、离子的静电力等这些弱相互作用的协同性、方向性和选择性, 可能决定着生物膜的结构和功能. 相似文献
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Phase behavior of ternary system involving surfactant‐like ionic liquid 1‐dodecyl‐3‐methylimidazolium chloride ([C12mim]Cl), water, and nonionic surfactant PEO‐PPO‐PEO block copolymer (Pluronic L64) is investigated at 25°C. Hexagonal (H1) and lamellar liquid crystal phase (Lα) are found in [C12mim]Cl/H2O/L64 system by using polarized optical microscopy (POM), small‐angle X‐ray scattering (SAXS) techniques and 2H NMR spectra. The phase structure (H1 phase), which is formed in [C12mim]Cl/H2O binary system, is not changed when L64 with a low concentration is added. However, phase transitions will occur from hexagonal to multiphases of H1 and cubic phases (C), then to Lα+C phases with constant [C12mim]Cl/H2O ratio and increasing L64 concentration. Moreover, at given L64 (5%, 20%) concentration, the lattice parameter of H1 or Lα phase decreases with increasing [C12mim]Cl/H2O ratio. Fourier transform infrared (FTIR) spectra indicate that the H‐bonded network comprising an imidazolium ring, chloride ion and water formed in [C12mim]Cl/H2O binary system is disrupted upon addition of L64. This is helpful to the phase transition, due to the decreasing of interfacial curvature induced by dehydration of hydrated layer after the addition of PEO block of L64. 相似文献
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Xueyan Zhao 《Journal of Dispersion Science and Technology》2013,34(8):1080-1085
The triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (L64, PEO13PPO30PEO13) in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) can form lamellar liquid crystalline (Lα). The effect of apolar cyclohexane molecules on the Lα phase was investigated by using polarized optical microscopy (POM) and small-angle x-ray scattering (SAXS). The results of POM and SAXS show that a suitable amount of cyclohexane can contribute to the formation of lamellar liquid crystals, and the ordering of Lα phase is increased. For comparison, the effect of polar water on Lα phase was explored. After adding water, both EO groups and [BF4]– anion can form hydrogen bonds with water molecules, which weakens the electrostatic interactions between L64 and [Bmim][BF4] and therefore the ordering of lamellar structures is destroyed. 相似文献
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Virgil Percec Prof. Mihai Peterca Dr. Yusuke Tsuda Prof. Brad M. Rosen Satoshi Uchida Prof. Mohammad R. Imam Dr. Goran Ungar Prof. Paul A. Heiney Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):8994-9004
The synthesis, and structural and retrostructural analysis of a library of second‐generation conical dendrons that self‐assemble into spherical supramolecular dendrimers is reported. This library consists of amphiphilic dendrons with n‐alkyl groups containing from 4 to 16 carbon atoms. The dendrons containing 6 to 16 carbon atoms in their n‐alkyl groups self‐assemble into spherical supramolecular dendrimers that self‐organize in a Pm n cubic lattice. The structural and retrostructural analysis of the Pm n lattices generated from the supramolecular dendrimers demonstrated that the volume of the aromatic core of the spherical dendrimers is not dependent on the number of carbon atoms from their alkyl groups. This result facilitated the calculation of the average values of the absolute electron density of the aliphatic and aromatic domains of the spherical supramolecular dendrimers. The relative intensity of the higher order diffraction peaks of the Pm n lattice increases as the volume of the aliphatic part of the sphere mediated by the number of carbon atoms in the n‐alkyl groups decreases. This study demonstrates the maximum increase of the relative intensity of the higher order diffraction peaks of the Pm n lattice generated from non‐hollow supramolecular dendrimers. 相似文献
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Conformation of liquid crystalline state in interaction between chemical materials and biomembrane in terms of modern physics 总被引:3,自引:0,他引:3
Manyimportantfunctionsintheprocessoflifearecloselyrelatedwiththeliquidcrystallinestateofbiomembrane.Sothestudyontheconformationoftheliquidcrystallinestateofbiomembranehasbeenoneofthefrontierdomainsoflifesciencesofar[1—4].Inrecentyears,theresultsofagoodm… 相似文献
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The nanocrystalline cubic phase of zirconia was found to be thermally stabilized by the addition of 3 to 40 mol % manganese. The nanocrystalline cubic, tetragonal and monoclinic phases of zirconia stabilized with manganese (III)oxide (Mn‐Stabilized Zirconia) were prepared by thermal decomposition of carbonate and hydroxide precursors. Both the crystallization and isothermal phase transitions associated with Mn‐SZ were studied using high temperature x‐ray diffraction and x‐ray diffraction of quenched samples. Cubic Mn‐SZ initially crystallized and progressively transformed to tetragonal, and monoclinic structures above 700°C. The nanocrystalline cubic Mn‐SZ containing 25 mol % Mn was found to have the greatest thermal stability, retaining its cubic form at temperatures as high as 800°C for periods up to 25 hours. Higher than 40 mol %, cubic Mn2O3 was found to coexist with cubic Mn‐SZ. The crystallite sizes observed for the cubic, tetragonal and monoclinic Mn‐SZ phases ranged from 50 to 137, 130 to 220, and 195 to 450 Å respectively, indicating, for ZrO2, that particle size was a primary factor in determining its polymorphs. The classical Avrami equation for nucleation and growth was applied to the observed phase transformations. 相似文献
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B. VazquezL.M. Torres-Martinez N. AlvarezJ.F. Vente P. Quintana 《Journal of solid state chemistry》2002,166(1):191-196
The subsolidus phase diagram, CaO-Al2O3-CoO, and its phase relations below 1300°C have been studied in air. The stability regions of nine subsolidus compatibility triangles were established and a new ternary phase was found. The structure of this compound, Ca3CoAl4O10 (orthorhombic, space group Pbc21, a=5.1452(2) Å, b=16.7731(5) Å, c=10.7055(3) Å), was determined from X-ray diffraction data and found to be isostructural with Ca3ZnAl4O10. This is an open framework compound with three crystallographically different channels, each with a diameter of ∼3.5 Å. The two end members of the binary CoO-CaO system are surrounded by small regions of solid solutions. Lab color parameters were measured in several compositions. No ternary phases were found when Co was substituted by other divalent cations such as Sr, Ba, Mn, Ni, Cu, Cd, Sn and Pb. 相似文献
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First Examples of de Vries‐like Smectic A to Smectic C Phase Transitions in Ionic Liquid Crystals
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Dr. Nadia Kapernaum Carsten Müller Svenja Moors M. Christian Schlick Eugen Wuckert Prof. Dr. Sabine Laschat Prof. Dr. Frank Giesselmann 《Chemphyschem》2016,17(24):4116-4123
In ionic liquid crystals, the orthogonal smectic A phase is the most common phase whereas the tilted smectic C phase is rather rare. We present a new study with five novel ionic liquid crystals exhibiting both a smectic A as well as the rare smectic C phase. Two of them have a phenylpyrimidine core whereas the other three are imidazolium azobenzenes. Their phase sequences and tilt angles were studied by polarizing microscopy and their temperature‐dependent layer spacing as well as their translational and orientational order parameters were studied by X‐ray diffraction. The X‐ray tilt angles derived from X‐ray studies of the layer contraction and the optically measured tilt angles of the five ionic liquid crystals were compared to obtain their de Vries character. Four of our five mesogens turned out to show de Vries‐like behavior with a layer shrinkage that is far less than that expected for conventional materials. These materials can thus be considered as the first de Vries‐type materials among ionic liquid crystals. 相似文献
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用同步辐射小角和宽角X光衍射实验技术研究了由二棕榈酰磷脂酰胆碱(DPPC)和豆固醇所形成的脂质体的液态有序相的结构性质. 结果表明液态有序相的小角X光衍射d值(d-spacing)随着固醇温度和浓度的变化仅有微小的改变. 与凝胶相及液晶相的宽角X光衍射d值相比, 液态有序相的宽角X光衍射d值有更宽的变化范围, 在30到52 °C的温度范围内, 液态有序相的宽角X光衍射d值从0.422 nm变化到0.460 nm. 电子云密度计算表明液态有序相的脂双层厚度和水层厚度都要大于与之平衡共存的液晶相的脂双层厚度和水层厚度. 电子云密度计算结果还表明液态有序相的脂双层厚度随温度升高而降低. 本研究结果对于从定量的角度认识 生物膜的相态及深入认识生物膜中的有序结构具有重要意义. 相似文献
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Margaret W. Frey John A. Cuculo Richard J. Spontak 《Journal of Polymer Science.Polymer Physics》1996,34(12):2049-2058
Solutions of cellulose in the ammonia/ammonium thiocyanate (24.5/75.5 w/w) solvent form several stable phases. Of particular interest in this work are the temperature-dependent liquid crystalline and gel phases which are stable at cellulose concentrations above 6% w/v. While the temperature-composition conditions yielding these phases are reasonably well established, very little is currently known about the morphological characteristics of lyotropic and gelled cellulose. Polarized light microscopy is employed here to demonstrate that solutions at temperatures above the gel melting point are birefringent, composed of liquid crystals. Field-emission scanning electron microscopy has been used to (i) examine the three-dimensional network in cellulose gels, and (ii) correlate network morphology with cellulose molecular weight and solution concentration. Results obtained from two complementary sample preparation techniques (i.e., critical point drying and freeze drying) are compared to identify and minimize artifacts, and reveal that gel formation occurs as the solutions phase-separate into polymer-rich anisotropic and solvent-rich isotropic phases. The polymer-rich phase is highly interconnected and forms a fibrillar network, with fibrils measuring 20–70 nm in diameter. © 1996 John Wiley & Sons, Inc. 相似文献