Entangled Porphyrins in Cyclodextrin Vesicles

The entanglement process between porphyrins and some amphiphiliccyclodextrins and the occurrence of different species have been proved by the combination of UV-Visabsorption, fluorescence anisotropy, resonance light scattering and ¹H NMR spectroscopy.     

Dynamic Light Scattering and NMR Studies of Napin

We analyze the structure of napin (BngNAP1), a storage protein (m.w. 14.5 kDa) from Brassica napus. On the basis of the results of ¹H NMR spectroscopy and dynamic light scattering (DLS) studies, the overall shape and secondary structure of the molecule are estimated.     

一种相变温度与人体正常体温相近的共聚高分子在水溶液中的自缔合行为

以N-异丙基丙烯酰胺和N-异丙基甲基丙烯酰胺为共聚单体,合成了一种在水溶液中具有与人体正常体温一致的相转变温度的共聚化合物．并从团簇理论出发,结合粘度数据推出了该共聚物在水中的动态接触浓度,利用动态光散射技术研究了这一特殊共聚物在动态接触浓度以上水溶液中的自缔合行为,讨论了从动态光散射实验得出的该共聚物的表观流体力学半径大小及分布与浓度的依赖关系．     

掺杂聚合物对溶致液晶结构的影响

利用聚合物大分子作构建组分,将其掺杂到不同类型表面活性剂构成的溶致液晶中,考察对液晶相结构的影响．利用小角X射线散射及偏光显微镜对聚合物掺杂前后液晶的结构进行表征,并讨论了聚合物与液晶模板间的相互作用．对阴离子型表面活性剂琥珀酸二异辛酯磺酸钠(AOT)／水液晶体系,聚合物的嵌入使层间距d增大;而对非离子表面活性剂十二烷基聚氧乙烯醚(C12EO4)／水体系,除小分子量的聚乙二醇PEG400外,其它聚合物嵌入使d减小,表明聚合物分子类型、大小及浓度对溶致液晶的结构参数甚至组装方式有不同的影响机制．     

液相卤化银纳米微粒的界面荧光和共振散射光谱特性

液相卤化银纳米微粒的共振散射光谱和发射光谱表明,AgCl和AgBr纳米微粒均在330,400,470和680nm处产生4个共振散射峰,在340,400和470nm处产生三个荧光峰．Ad纳米微粒在340,400,437,470和680nm处产生5个共振散射峰;除在340,400和470nm处产生3个荧光峰外,在434nm处有一最强的荧光峰．卤化银纳米微粒体系的浓度对共振散射信号的影响与浓度对荧光强度的影响一致,Aga,AgBr和AgI体系的共振散射光信号强度分别约为荧光信号的110,130和80倍,即荧光与共振散射之间存在相关性．提出了液相AgX纳米微粒荧光产生机理,解释了荧光与共振散射之间存在相关性的原因．     

Mineral–water interfacial structures revealed by synchrotron X-ray scattering

Chemical reactions occurring at the mineral–water interface are controlled by an interfacial layer, nanometers thick, whose properties may deviate from those of the respective bulk mineral and water phases. The molecular-scale structure of this interfacial layer, however, is poorly constrained, and correlations between macroscopic phenomena and molecular-scale processes remain speculative. The application of high-resolution X-ray scattering techniques has begun to provide substantial new insights into the molecular-scale structure of the mineral–water interface. In this review, we describe the characteristics of synchrotron-based X-ray scattering techniques that make them uniquely powerful probes of mineral–water interfacial structures and discuss the new insights that have been derived from their application. In particular, we focus on efforts to understand the structure and distribution of interfacial water as well as their dependence on substrate properties for major mineral classes including oxides, carbonates, sulfates, phosphates, silicates, halides and chromates. We compare these X-ray scattering results with those from other structural and spectroscopic techniques and integrate these to provide a conceptual framework upon which to base an understanding of the systematic variation of mineral–water interfacial structures.     

Hydrodynamic Radius Characterization of a Vinyl-Type Polynorbornene by Size-Exclusion Chromatography with a Static and Dynamic Laser Light Scattering Detector

Both absolute molecular weight and molecular sizes (radius of gyration and hydrodynamic radius) of a vinyl-type polynorbornene eluting from size-exclusion chromatography columns were determined by combined with a static and dynamic laser light scattering detector. The hydrodynamic radius of polymer fraction eluting from size-exclusion chromatography columns was obtained from dynamic laser light scattering measurements at only a single angle of 90° by introducing a correction factor. According to the scaling relationship between molecular sizes and molecular weight and the ratio between radius of gyration and hydrodynamic radius, the vinyl-type polynorbornene took a random coil conformation in 1,2,4-trichlorobenzene at 150 °C.     

Development of a Solid-Phase Extraction Procedure for the Simultaneous Determination of Polyphenols, Organic Acids and Sugars in Wine

A solid-phase extraction (SPE) procedure that fractionates wine samples into 2 sub-samples containing sugars and organic acids (sub-sample 1) and low molecular weight polyphenols (sub-sample 2), respectively, together with rugged LC procedures for their analyses are described. Wine is adjusted to pH 2.5 and loaded on a styrene-divinylbenzene (SDB) cartridge. The organic acids and sugars are eluted with 20 mM sulphuric acid and the monomeric polyphenols with ethyl acetate. Glucose and fructose are analysed by normal phase LC with evaporative light scattering detection and the organic acids by ion exclusion chromatography with UV detection at 210 nm. Analysis of the phenolic fraction is performed by reversed phase LC with diode array detection. Recoveries and repeatabilitys for 27 standard compounds (2 sugars, 7 organic acids and 18 polyphenols) are presented. The method represents an improvement in terms of productivity and robustness compared to currently used procedures.     

LAXS investigation of finger phantoms

Osteoporosis is a bone condition that is caused mainly by the degradation of trabecular and cortical bone resulting in the decrease of bone strength and eventually leads to bone fracture. A low angle X-ray scattering (LAXS) system that uses mainly the coherent scattering process for the characterisation of materials was constructed to study such bone conditions. Several finger phantoms were fabricated to simulate bone of varying densities. The LAXS method was able to identify the changes in bone density quite well by comparing energy dispersive X-ray diffraction patterns as well as the angular patterns. Quantitative information can be extracted from such patterns that relate to bone loss. Signature patterns at low exposure times were produced in order to reduce the dose received with reasonable identification power but at slightly higher statistical errors compared with long exposure patterns. Use of other parameters to increase the sensitivity was attempted.     

Small angle X-ray scattering from lamellar phase for β-3,7-dimethyloctylglucoside/water system: comparison with β-n-alkylglucosides

Small angle X-ray scattering (SAXS) is measured for the lamellar phase in aqueous systems of 1-o-β-3,7-dimethyoctyl-D-glucopyranoside (β-Glc(Ger)), which has recently been prepared by us, 1-o-β-decyl-D-glucopyranoside (β-GlcC₁₀), and 1-o-β-octyl-D-glucopyranoside (β-GlcC₈). The repeat distance d obtained from the position of the diffraction peak does not follow the swelling law d = 2δ_hc/_hc, where δ_hc and _hc are the thickness and the volume fraction of the hydrophobic layer, respectively. This may result from the fact that δ_hc increases and, equivalently, the surface area per surfactant molecule (a_s) decreases with increasing concentration. So we calculate δ_hc and a_s from the observed d value at each concentration using the above swelling law. The half-thickness δ_hc increases in the order β-GlcC₈ < β-Glc(Ger) < β-GlcC₁₀ at a fixed concentration. On the other hand, the data on a_s for β-GlcC₁₀ and β-GlcC₈ lie on the same line and the data for β-Glc(Ger) lies above this line. These results suggest that the cross-sectional area of the geranyl chain is larger than that of the glucose headgroup. Existence of water filled defects in bilayer sheets is also discussed based on the SAXS pattern and the concentration dependence of d.