溶剂萃取法制备Co(PO_3)_2超细微粉

本文用溶剂萃取法成功地制备了偏磷酸钴超细微粉并通过ＸＲＤ，ＩＲ，ＴＧ，ＤＴＡ，ＴＥＭ等实验对超细微粉的组成、结构进行了表征。     

Hole Burning and Fluorescence Spectra of Sol-Gel Derived Sm2+-Doped Glasses

Sm2+-doped glasses in the system of Al2O3-SiO2 were prepared by sol-gel processing of metal alkoxides and reacting with H2 gas at 800°C. The hole burning properties of these glasses were investigated. The holes were burned in the 7F0 5D0 line of the Sm2+ ions using a DCM dye laser at 77 K. The hole depth increased with increasing the laser irradiation time, reaching up to 15% of the total intensity within a few hundred seconds. The hole width was 3 cm–1 full width at half maximum. Fluorescence line narrowing spectra of the 5D0 7 F1 transition were analyzed to study the local structure surrounding the Sm2+ ion. It is concluded that the Sm2+ ions are closely coordinated with nine oxygens of the AlO6 group in aluminosilicate glasses and that the addition of Al3+ ions into glass induces an increase in the coordination number of the Sm2+.     

Epoxy-based azo molecular glasses with four-arm architecture: Preparation,characterization and holographic recording

A series of epoxy-based azo molecular glasses with four-arm architecture was synthesized, characterized and applied to holographic recording.     

A DSC study of the effects of sugars on thermal properties of rice starch gels before and after aging

Thermal characterization of gelatinized binary rice starch-water and ternary starch-sugar-water gels before and after aging was carried out using differential scanning calorimetry. The glass transition temperature of the maximally freeze-concentrated solution (T_g) in both fresh and aged gels was observed to decrease progressively with increasing sugar concentration. Aging of the gels generally shiftedT_g to higher temperatures, but had little or no effect on the ice melting peak temperature (T _m). The presence of various sugars could either accelerate or retard starch (amylopectin) recrystallization, depending on the type and concentration of sugar, as well as on starch/water ratio. A hypothesis based on the dual antiplasticizing-plasticizing effects of sugars was postulated to explain the observed effects. Of the sugars studied, xylose and fructose appeared to display exceptional retardative and accelerative effects, respectively, on retrogradation.This study was funded by a Sixth Malaysia Plan R&D grant under the Intensification of Research Priority Areas (IRPA) Program of the Ministry of Science, Technology and Environment, Malaysia. We thank Dr. Harry Levine and Dr. Louise Slade for giving us the opportunity to contribute a paper to this special issue of JTA.     

一种非晶硅膜改性弹性玻璃毛细管交联中等极性固定相色谱柱的制备

研究了非晶硅膜改性的弹性玻璃毛细管交联ＯＶ－１７０１中等极性固定相色谱柱。在适当温度下，采用过氧化二异丙苯（ＤＣＵＰ）游离基引发交联ＯＶ－１７０１固定液，成功地制备了交联ＯＶ－１７０１柱，该柱具有柱效高、惰性好、耐溶剂、抗腐蚀和耐高温等性能，是一种新型高性能的中等极性交联柱。     

Glass capillary columns for separation of free organic acids

Glass capillary columns have been prepared without acidic additive in the stationary phase, from which free organic acids elute as sharp and symmetrical peaks. The required surface in the borosilicate glass capillary was generated by a combination of leaching with aqueous HCl and deposition of colloidal silica particles; it can be coated with stationary phases have a broad range of polarity. Aqueous samples containing free organic acids can also be analyzed in such columns in an isothermal mode.     

Effects of Poly(ethylene glycol) Doping on the Behavior of Pyrene, Rhodamine 6G, and Acrylodan-Labeled Bovine Serum Albumin Sequestered within Tetramethylorthosilane-Derived Sol-Gel-Processed Composites

We investigate the effects of controlled poly(ethylene glycol) (PEG) doping on the behavior of pyrene, rhodamine 6G (R6G), and acrylodan-labeled bovine serum albumin (BSA-Ac) sequestered within tetramethylorthosilicate (TMOS)-derived sol-gel-processed materials. To probe the dipolarity of the local environment within the composite we performed static fluorescence measurements on pyrene as the composites aged. We found that small levels of PEG loading effected significant enhancements in the local dipolarity surrounding the average pyrene molecule. Time-resolved fluorescence anisotropy measurements were used to follow the rotational reorientation dynamics of R6G as the composites aged. As the PEG loading increased, the R6G reorientational mobility increased. Nitrogen adsorption techniques were used to quantify the effects of PEG doping level on the surface area and final xerogel pore features. A large reduction in surface area was observed with PEG doping, but no detectable change in pore size was noted. The effects of PEG doping on a biomolecule were probed by following the time-resolved fluorescence anisotropy decay of BSA-Ac. These results showed that PEG doping resulted in increased biomolecule dynamics relative to that found for a neat, undoped TMOS-derived composites. Together these results show that PEG doping can be used to tune the sol-gel-processed composite dipolarity, alter the mobility of dopants sequestered within the composite, control analyte acessibility to the sensing chemistry, and modulate the internal dynamics within a biodopant.     

Thermal analysis,state transitions and food quality

Thermal properties of food systems are important in understanding relationships between food properties and changes in food quality. Concentrated food systems (low-moisture and frozen foods) are seldom in an equilibrium state and they tend to form amorphous, non-crystalline structures. Several glass transition-related changes in such foods affect stability, e.g., stickiness and caking of powders, crispness of snack foods and breakfast cereals, crystallisation of amorphous sugars, recrystallisation of gelatinised starch, ice formation and recrystallisation in frozen foods and rates of non-enzymatic browning and enzymatic reactions. Relationships between glass transition, water plasticisation and relaxation times can be shown in state diagrams. State diagrams are useful as stability or quality maps and in the control of rates of changes in food processing and storage.This revised version was published online in November 2005 with corrections to the Cover Date.     

Über den Einfluß von Temperatur und Fremdionen auf Eigenschaften und Bau der Natriumwasserglaslösungen

The Influence of Temperature and Impurities Addition on the Properties and the Constitution of Sodium Water Glass Solutions Sodium water glass (NaWG-)solutions of constant composition (SiO₂/Na₂O = 3,3; C_SiO2 = 6,2 M) and different concentration of impurities (Fe, Al, Ti, Cu, chloride, sulfate) were investigated in dependence on temperature by means of the dye absorption method, ¹H- and ²³Na-NMR spectroscopy. It is shown, that the differences in the dye absorption spectra of normalized technical NaWG-solutions, mainly depend on the Fe-concentration in the solutions and their thermal history. From the results follow a crosslinking of polymeric silicate species by Fe? O? Si bonds and/or hydrogen bridges and a fully or partially degradation of these bonds at higher temperatures (150°C).     

Hydrogen Gas Sensing of High Electrical Conducting-P2O5-SiO2 Glasses Prepared by Sol-Gel Process

High proton-conducting P₂O₅-SiO₂ glass was applied to the electrolyte of the hydrogen concentration cell for hydrogen gas sensing. 5P₂O₅·95SiO₂ glass was prepared using the sol-gel method and its electrical conductivity and electromotive force were measured at 50°C as a function of both the ambient humidity and hydrogen gas concentration. The electrical conductivities increased with increasing humidity and reached 10^–2 S/cm at 90% relative humidity. The electromotive force of the hydrogen concentration cell, where the glass was used as a membrane, showed good Nernstian response to hydrogen pressure in the high relative humidity region.