Kinetic-Turbidimetric Determination of Stachyose Based on Its Inhibitory Action on Sucrose Crystallization.

Abstract

The effects of 9 saccharides on the crystallization of sucrose have been comparatively studied with analytical purposes. A sensitive (detection limit 0.1 μg mL^?1) and simple kinetic turbidimetric procedure is used for determination of stachyose, based on its inhibitory action on the crystallization of sucrose. The supersaturated solutions of sucrose were prepared by addition of acetone to stable water sucrose solutions. The induction period of the crystallization process was turbidimetrically measured. Controlled constant stirring and temperature are convenient in order to obtain reproducible results. The method was applied to the determination of stachyose in synthetic mixtures.     

LaCo0.9Cu0.1O3的蔗糖溶胶-凝胶法合成及二甲苯催化氧化性能研究

蔗糖溶胶 凝胶法合成了稀土钙钛矿型复合氧化物LaCo0 .9Cu0 .1 O3,并对其进行了XRD ,BET ,TPR表征和二甲苯催化氧化性能测试 ,并与柠檬酸溶胶 凝胶法作了比较。结果表明 ,蔗糖作为络合剂成胶和干胶容易 ,粒径较小 ,具有进一步降低LaCo0 .9Cu0 .1 O3形成温度的作用 ,以蔗糖作为络合剂在 70 0℃所制备的催化剂LaCo0 .9Cu0 .1 O3低温活性较好。     

Enzyme thermistors for process monitoring and control

In today’s biotechnology there is an increasing demand for appropriate analytical systems for process control. At present the most widely used control systems are based on measurements of pH, pO₂, and pCO₂. Such systems do not allow the direct measurement of substrates and products. To overcome this drawback sensors such as enzyme thermistors and enzyme electrodes have been designed and their development into industrial useful sensors for monitoring and controlling is the subject of active research.     

Use of Sucrose‐based Epoxy ­Formulations and Cellulosic Fibers in ­the Design,Preparation, and Screening ­of New Composite Insulation Materials

Non‐woven composite insulation materials were generated from cotton, kenaf, jute, polyester, polypropylene, sucrose‐based epoxy formulations, and aluminum foil. The needlepunched fiber batts were rendered flame resistant by use of inorganic reagents and urea. To discover suitable epoxy formulations to bind the cellulose fibers to themselves or to dissimilar surfaces and to make flexible composites, a comparison of the performance of the known epoxy allyl sucroses (EAS), epoxy crotyl sucroses (ECS), and diglycidyl ether of bisphenol‐A (DGEBA) was made. The epoxies were cured with commercial diethylenetriamine (DETA), and UNIREZs‐2142 and 2355®, to discover a formulation with the following characteristics: (a) low cure temperature; (b) low Young's moduli and glass transition temperatures of cured thermosets for flexible composites; (c) ample bond strength between the fabric and the bonded surfaces; and (d) non‐cytotoxicity and non‐mutagenicity of the epoxies. Based on results following these criteria, EAS was selected, and the formulation comprising EAS and UNIREZ‐2355® was deemed suitable to bind fiber batts to surfaces of any type and geometry. ASTM guidelines were used to construct a wooden frame cube (heat box) for the simultaneous rapid screening of cellulosic fiber batts and composites. The new materials were compared against R‐19 fiberglass insulation for their ability to resist heat flow (denoted by relative R‐values) and time taken to approach thermal equilibrium. Plain non‐woven cellulosic fiber batts showed relative R‐values of 4.0 °F ft² hr/Btu per inch thickness (0.27 K m²/W per cm), and took about 2 hr to establish equilibrium heat flow. Commercial fiberglass batts showed relative R‐values­of 2.2 per in (0.15 per cm) and took 1 hr to attain equilibrium heat flow. When 6.25 in (15.9 cm) thick batts of fiberglass were needle punched to a thickness of 1 in (2.54 cm), relative R‐values and equilibrium heat flow times were 4.0 per in (0.27 per cm) and 2 hr, respectively. This denoted that the densities and thermal resistances of non‐conducting materials are raised concurrently. Anisotropic heat flow behavior was observed in cellulosic fiber composites with aluminum foil (shiny side out) bonded on one side. It depended upon whether the aluminum foil side or the fibers side faced the heat source. In the latter orientation the aluminum acted as a heat sink, and in the former orientation the foil acted as a poor heat reflector. The poor performance of these insulation composites was related to the fact that aluminum was directly bonded to the fiber batts and was acting as a heat conductor. When cellulose fiber shims (spacers) were placed between the fiber batts and the aluminum foil, the R‐values of the composites were comparable to those of plain batts but the times taken to approach thermal equilibrium increased to >3 hr, denoting that the foil was acting more as a reflector and less as a conductor. Copyright © 2001 John Wiley & Sons, Ltd.     

Instabilities in free diffusion boundaries of NaCl-sucrose-H2O solution at 25°C

The four diffusion coefficients for the system sucrose (0.097M)-NaCl-(0.291M)-water at 25°C have been measured by the Gouy interferometric technique. The cross terms D₁₂ and D₂₁ are small However, if sucrose or NaCl are chosen as component 3 instead of water, one of the cross terms becomes very large. Several runs were used to test the McDougall analysis of gravitational instability in diffusion boundaries for three component systems. Growth of convective motions at the center and at the edges of the boundary have been observed that confirm the McDougall model.     

Application of 1′,2,3,3′,4,4′-Hexa-O-benzylsucrose in the Preparation of Sucrose Macrocycles via a Click Chemistry Route: Regioselectivity Study

Abstract

1′,2,3,3′,4,4′-Hexa-O-benzyl-sucrose was applied in the preparation of sucrose-based macrocycles via a click chemistry route. This was realized by protection of the 6′?OH with silyl block followed by elongation of the glucose end with the ?CH₂CH₂N₃ unit. Removal of the silyl block and subsequent propargylation of the released C6′?OH afforded the corresponding synthon, cyclization of which under the click condition provided the desired macrocycle with the expected 1,4-pattern of substituents at the triazole ring.     

Simple preparation of hollow carbon sphere via templating method

The hollow carbon sphere (HCS) was synthesized using silica particle and sucrose as a template and carbon precursor, respectively, under a hydrothermal condition. The prepared HCS were characterized by SEM, TEM and N₂ adsorption. The prepared HCS showed uniforms size and high mesoporosity. It was found that the presence of acidic site on the silica particle templates would be crucial for the preparation of the HCS. Without the acidic site on silica particles, the macroporous carbon with high microporosity was prepared. It was found that the method employed in this work was highly suitable for the preparation of monodisperse HCS.     

一种新型CO2/原油助混剂CAA8-X的应用与助混机理

CO₂驱是一种具有广阔前景的提高油藏采收率的方法。其中,降低CO₂与原油的最低混相压力以实现混相驱是增强CO₂驱效果的重要手段。由此我们设计了由亲油基团十六烷基和亲CO₂基团全乙酰蔗糖酯基结合的新型“亲油-亲CO₂助混分子”十六酸全乙酰基蔗糖酯CAA8-X,研究发现,CAA8-X对超临界CO₂流体和不同油相的煤油、白油以及长庆原油有优异的助混效果,界面张力消失法和细管实验法测定结果表明,CAA8-X可以将超临界CO₂/长庆原油的最低混相压力降低20.5%。用分子动力学模拟计算了CO₂分子与全乙酰蔗糖酯基的亲和能力,研究了这类新型“亲油-亲CO₂助混分子”通过多酯头基降低与CO₂亲和势能而降低油/CO₂界面能的助混机理。     

Synthesis and biodegradation studies of new copolymers based on sucrose derivatives and styrene

Novel unsaturated esters of sucrose were synthesised directly and in good yields from sucrose using a simple, mild, and selective Mitsunobu procedure. These regioisomerically pure vinyl sugars have been copolymerised with styrene by a free radical process, yielding unbranched linear polymer materials with pendant sucrose moieties. Their physical properties indicate that these polymers have potential technological relevance as amphiphilic and biodegradable materials. Biodegradation tests on the copolymer samples by a fungal (Aspergillus niger) culture method showed a fungal growth ?60%, indicating good biodegradability and that the copolymers were partially bio-assimilated during microbial attack.     

应用阳离子交换树脂催化水解蔗糖Ⅰ.蔗糖非均相催化水解反应动力学

实验选用两种H+型强酸性阳离子交换树脂为催化剂，研究蔗糖在离子交换树脂柱内的非均相催化反应动力学。结果表明，温度每升高10℃，蔗糖在两种离子交换树脂柱内的水解速度分别增加到2．1和3．3倍；蔗糖在两种离子交换树脂柱内水解反应的表观活化能分别为64．96kJ／mol和79．59kJ／mol，其水解反应有明显的扩散控制。