蔗糖水解Belousov-Zhabotinskii体系非线性动力学行为

B-Z振荡;蔗糖水解Belousov-Zhabotinskii体系非线性动力学行为     

Spectroscopic characterization of the chemical composition of the potent sweetener Vartamil

The chemical composition of the potent sweetener Vartamil was characterized using spectral methods. It was demonstrated that Vartamil is a mixture of saccharose chloro derivatives, the main one of which is 4,1′,6′-trichloro-4,1′,6′-trideoxygalactosaccharose (Sucralose). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 159–163, March–April, 2008.     

锰源对燃烧法制备5V级正极材料LiNi0.5Mn1.5O4的影响

以硝酸锰和醋酸锰,采用蔗糖燃烧法制备锂离子电池正极材料LiNi0.5Mn1.5O4通过XRD、SEM、粒径分布测试、循环伏安、恒流充放电测试以及交流阻抗等方法,研究了醋酸锰和硝酸锰对产物的结构、形貌、粒径及电化学性能的影响。XRD测试结果表明样品的结构都为立方尖晶石型,属于Fd3m空间群。不同的锰源对材料的粒径及粒径分布有很大的影响。以醋酸锰为原料制得的材料的粒径较小并且分布更均匀,有利于锂离子的脱出和嵌入从而提高电化学性能。以醋酸锰为锰源制得的LiNi0.5Mn1.5O4在3.6~5.2 V的充放电电压范围内的电化学性能更好,1C(1C=140.0 mA.g-1)倍率的首次放电容量为144.5 mAh.g-1,循环100周后容量保持率为96%,在3C,5C,10C以及20C的放电容量分别为136.3,132.0,124.7以及96.6 mAh.g-1。     

Ziegler-Natta catalysed polymerisation for the preparation of copolymers with pendant sucrose moieties

The copolymerisations of the monomers 1 (1′,2,3,3′,4,4′,6-hepta-O-benzyl-6′-O-crotonyl-sucrose) and 2 (1′,2,3,3′,4,4′,6-hepta-O-benzyl-6′-O-methacryloyl-sucrose) with styrene/methyl methacrylate have been examined in the presence of Ziegler-Natta catalyst TiCl₄/AlEt₃. A study of the effect of the reaction conditions, the monomer structure and the initial quantity of the comonomers on the sugar incorporation and molecular mass of the final copolymers has been carried out. In this way, by the coordination mechanism of polymerisation we had obtained novel linear unbranched polymers and copolymers, potentially useful for biomedical applications.     

不同碳源制备的介孔碳分子筛的性能研究

以介孔分子筛SBA-15为模板剂,分别采用蔗糖、糠醇和酚醛树脂作为碳源制备介孔碳分子筛.用TGA、XRD、N2吸附-脱附和TEM对制备的样品进行了表征和比较.结果表明,三种碳源制备的介孔碳分子筛的结构有序性明显不同.用蔗糖为碳源能够得到结构高度有序的介孔碳分子筛,其比表面积和孔容最大,分别为1 422 m2·g和1.15 cm3·g;用糠醇为碳源制备的样品次之;用普通酚醛树脂为碳源制备的样品其结构有序性最差.     

红枣中果糖、葡萄糖与蔗糖的高效液相色谱示差检测分析

建立了同时分析鲜红枣中果糖、葡萄糖和蔗糖的高效液相色谱方法.利用鲜红枣样品进行添加回收实验,获得方法对果糖、葡萄糖和蔗糖测定的平均回收率分别为93.5%、91.8%和89.8%,变异系数3.27%、2.34%、5.86%.结果表明:采用高效液相色谱示差分析方法定量检测鲜红枣中果糖、葡萄糖和蔗糖快速、简便.同时得出方法的检出限为:果糖5.73×10-3mg/mL,葡萄糖5.22×10-3mg/mL,蔗糖3.59×10-3mg/mL,测定结果符合食品检测要求.     

A selective pulse sequence for the determination of long‐range C,H spin coupling constants

A new pulse sequence for determining scalar long range C,H spin couplings in small organic molecules is proposed. It is based on the combination of a selective J‐resolved spectrum with a selective HMBC and displays the long‐range spin couplings of one chosen carbon atom in the indirect dimension. Advantages and disadvantages are discussed on example spectra of ethanol, strychnine and sucrose. Copyright © 2003 John Wiley & Sons, Ltd.     

碳热还原原位合成锂离子电池硅/碳复合负极材料研究

以一氧化硅和蔗糖为原料,通过高能球磨和后续热解原位制备硅/碳复合材料。采用X射线衍射仪(XRD)和高分辨透射电子显微镜(HRTEM)对其进行了表征,得到的纳米(小于50 nm)硅颗粒均匀地分散于无定形碳基体中。复合材料电极电化学测试显示,循环50次其可逆容量仍保持在650 mAh·g-1以上,平均每次容量衰减率仅为0.27%。优异的电化学性能主要归因于原位生成的纳米硅颗粒处于无定形碳基体中对其体积变化具有良好的缓冲作用及纳米硅颗粒周围的石墨相对于导电性的改善。     

Rapid detection of sucrose adulteration in honey using Fourier transform infrared spectroscopy

Abstract

Honey authenticity is of great importance for commercial and health reasons. The most common adulteration methods are overfeeding of bees with sugar or by adding sucrose. In the study, a Fourier transform infrared spectroscopy based on chemometric method, a partial least squares, for determination of sucrose sirup adulteration of Turkish honeys was improved. For this purpose, honey samples were adulterated with known amounts of sucrose sirup in concentrations ranging between 5.94 and 27.80%. A calibration curve was constructed within 992–923?cm^?1 with the regression coefficient of 0.999. Obtained results from the spectra were confirmed by high performance liquid chromatography-refractive index detector and a good correlation was found between the results of the spectroscopic and chromatographic methods. Additionally, some method validation parameters (linearity, repeatability, limit of detection, and quantification) of the spectroscopic method were studied and obtained results were compared with chromatographic method. To prove the usefulness of the method, twenty different honey samples were collected from markets in Turkey and analyzed for sucrose contents. The results indicated that predicted sucrose concentration of honey samples by the spectroscopic method ranged between 4.52 and 15.16% and results were confirmed by the chromatographic method with high correlation (correlation coefficient = 92%). The results of the present indicated showed that adulteration ratio of honey samples by sugar addition can be detected using Fourier transform infrared spectroscopy technique in a short time with high accuracy. In conclusion, this method could be regarded as a new alternative technique for routine analysis in quality control of honey samples.     

EPR studies on aqueous sucrose solutions using (Cu(H2O)6)2+ spin probe

EPR investigations using Cu²⁺ ion as a probe have been performed on supersaturated sucrose solution with percent concentration c = 66 as a function of temperature T, and at room temperature as a function of c. The motionally averaged spectrum of [Cu(H₂O)₆]²⁺ was used to monitor the changes in intermolecular interactions that occur as a function of [c, T]. A drastic increase in the line width, symptomatic of increase in the rotational correlation time of [Cu(H₂O)₆]²⁺, is observed between 293 and 288 K. The motionally averaged spectrum disappears below 281 K. The motionally averaged spectrum is also absent in the room temperature spectra of the solution with c= 85. Even in the [c, T] range where [Cu(H₂O)₆]² is found to be nearly static, these molecules appear to have an orientational fluctuation manifesting in the m ₁ dependence of the line width of the parallel component.