氯代脱氧蔗糖合成的研究

4,6-原乙酸蔗糖六乙酸酯在酸催化下水解和醇解, 选择性地保护了蔗糖分子中的某些羟基, 并通过乙酰基由C~4→C~6迁移的异构化反应合成了一系列蔗糖乙酸酯。利用Vilsmeier试剂作为氯化试剂与蔗糖乙酸酯进行氯化反应, 再除去乙酰基, 合成了六个氯代脱氧蔗糖, 其中的三个由于C~4构型的转换, 为氯代脱氧半乳蔗糖。     

蔗糖酯的酶催化区域选择性合成

酶可以区域选择性地合成蔗糖酯，枯草杆菌等蛋白酶被用来区域选择性合成 1'-O-蔗糖酯，且通常不接受长链（大于C_(12))脂肪酸作为酰基授体，而脂肪酶可 催化宽范围的脂肪酸，除了脂肪酶和蛋白酶外，研究发现抗体酶也能区域和立体选 择地酰化蔗糖。蔗糖二酯、线型蔗糖酯都可以通过酶催化区域选择性地合成。酶催 化合成蔗糖酯通常在二甲基甲酰胺、二甲基亚砜和吡啶等有毒溶剂中进行。近几年 来，无溶剂条件下酶催化合成蔗糖酯，以及用叔丁醇等毒性较小的溶剂代替毒性较 大的溶剂的研究，也越来越受重视。     

丙氨酸在葡萄糖和蔗糖水溶液中的体积性质

利用精密数字密度计分别测定了丙氨酸在不同组成的葡萄糖和蔗糖水溶液中的密度,计算了丙氨酸的表观摩尔体积、极限偏摩尔体积和理论水化数,根据结构水合作用模型讨论了迁移偏摩尔体积的变化规律,并与乙二醇-水和丙三醇-水等多羟基体系作了比较.结果表明,丙氨酸分子在多羟基化合物-水体系中体积效应的大小与多羟基化合物所含OH基数目有关.     

Effect of Spontaneous and Water-Based Passivation on Components and Parameters of Ti6Al4V (ELI Grade) Surface Tension and Its Wettability by an Aqueous Solution of Sucrose Ester Surfactants

Solid wettability is especially important for biomaterials and implants in the context of microbial adhesion to their surfaces. This adhesion can be inhibited by changes in biomaterial surface roughness and/or its hydrophilic–hydrophobic balance. The surface hydrophilic–hydrophobic balance can be changed by the specifics of the surface treatment (proper conditions of surface preparation) or adsorption of different substances. From the practical point of view, in systems that include biomaterials and implants, the adsorption of compounds characterized by bacteriostatic or bactericidal properties is especially desirable. Substances that are able to change the surface properties of a given solid as a result of their adsorption and possess at least bacteriostatic properties include sucrose ester surfactants. Thus, in our studies the analysis of a specific surface treatment effect (proper passivation conditions) on a biomaterial alloy’s (Ti6Al4V ELI, Grade 23) properties was performed based on measurements of the contact angles of water, formamide and diiodomethane. In addition, the changes in the studied solid surface’s properties resulting from the sucrose monodecanoate (SMD) and sucrose monolaurate (SML) molecules’ adsorption at the solid–water interface were also analyzed. For the analysis, the values of the contact angles of aqueous solutions of SMD and SML were measured at 293 K, and the surface tensions of the aqueous solutions of studied surfactants measured earlier were tested. From the above-mentioned tests, it was found that water environment significantly influences the components and parameters of Ti6Al4V ELI’s surface tension. It also occurred that the addition of both SMD and SML to water (separately) caused a drop in the water contact angle on Ti6Al4V ELI’s surface. However, the sucrose monolaurate surfactant is characterized by a slightly better tendency towards adsorption at the solid–water interface in the studied system compared to sucrose monodecanoate. Additionally, based on the components and parameters of Ti6Al4V ELI’s surface tension calculated from the proper values of components and parameters of model liquids, it was possible to predict the wettability of Ti6Al4V ELI using the aqueous solutions of SMD and SML at various concentrations in the solution.     

Degradation of Sucrose and Nitrate Over Titania Coated Nano-hematite Photocatalysts

Photodegradation of sucrose and/or nitrate in aqueous solutions was studied over the titania coated nano-hematite photocatalysts under near-UV irradiation. The efficiency of the photocatalytic oxidation and reduction of these coated particles was compared to the prepared single phase TiO₂. It was found that in different environments (O₂ or N₂) the particles showed differences in the photocatalytic efficiency due to the different reaction mechanisms. Effect of nitrate on sucrose degradation was investigated. In aerobic conditions, sucrose was degraded effectively while nitrate reduction was insignificant due to the fast reoxidation of nitrite by O₂ in the dark and by OH^. in homogeneous reaction. Since nitrite competes with sucrose for hydroxyl radicals, it has an adverse effect when the aerobic system contains both substrates. Since reoxidation was suppressed in N₂ conditions, greater reduction of nitrate was observed. The result showed clearly that in the absence of O₂, CO₂ production from sucrose mineralisation was limited by the amount of oxygen produced from the nitrate decomposition. Partial photodissolution of Fe ions for the coated samples was also observed in both environments.     

蔗糖衍生物甜味剂的呈味机理及其在三氯蔗糖研究中的应用

简述了甜味剂呈味机理的研究历程,着重介绍了AH-B-X理论和多点结合理论及其在三氯蔗糖研究中的应用,并指出了研究甜味机理的意义,为寻找和合成新型的人工甜味剂提供了理论依据和指导.     

歧化松香蔗糖酯的合成

先将歧化松香与二氯亚砜反应制备歧化松香酰氯,然后与蔗糖发生O-酰化反应合成了歧化松香蔗糖酯。用TLC、IR、13C NMR、UV、HPLC和HPLC-MS等多种方法对目标产物进行了分析和表征,结果显示歧化松香蔗糖单酯是所合成的目标产物中的绝对优势成分,含量可高达96·31%,酯基可能与蔗糖分子中果糖环上的C-1′相接。从目标产物的临界胶束浓度CMC(0·9×10~(-2)mol·L~(-1),此时表面张力σCMC=52·03mN·m~(-1))可知,所制备的歧化松香蔗糖酯具有较好的表面活性。     

Lyophilized hemoglobin‐albumin cluster with disaccharides: Long‐term storable powder of artificial O2‐carrier

Core‐shell protein cluster comprising a hemoglobin (Hb) in the center and human serum albumins (HSA) at the exterior, Hb‐HSA ₃ cluster, is an artificial O₂‐carrier designed for use as a red blood cell (RBC) substitute. Lyophilization of the Hb‐HSA ₃ cluster solution ([Hb unit] = 5 g/dL) with sucrose and trehalose yielded stable pink powder, which can be stored for 2 years at 4°C. Addition of pure water to the powder regenerated the homogeneous solution. The O₂‐binding properties and oxyHb rate have been unaltered during the storage period. Infrared spectroscopic studies revealed that the hydrogen bond between protein and sugar stabilizes three‐dimensional structure of the cluster.     

Synthesis and characterization of perovskite-type La1-yCayMn1-xB″xO3±δ nanomaterials (B″ = Ni,Fe; x = 0.2, 0.5; y = 0.4, 0.25)

Perovskite-type nanomaterials of the compositions La_1-yCa_yMn_1-xB″_xO_3±δ with B’’ = Ni, Fe; x = 0.2, 0.5 and y = 0.4, 0.25 were prepared using two different preparation routes (synthesis by precipitation and the PVA/sucrose method) at 500 °C–700 °C. The calcined products of the syntheses were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and physisorption measurements. The materials from the PVA/sucrose method contain particles with diameters from 33 nm to 48 nm, generate specific surface areas up to 33 m²/g and form pure compared to 45 nm–93 nm and up to 18 m²/g from precipitation method which contain a significant amount of sodium ions. The agglomeration process was analyzed for one nanomaterial (B’’ = Fe, x = 0.2, y = 0.4) from the PVA/sucrose method using temperature dependent XRD showing only a slight growth (4.3%) of nanoparticles at 600 °C. The materials from the PVA/sucrose method turned out to be more suitable as electrode materials in electrochemical applications (SOFC, sensors) because of smaller particle sizes, higher specific surface areas and purity.     

简易模板法制备有序介孔碳

通过一种简易的模板法制备了有序介孔碳,即硅/P123三嵌段共聚物复合物经硫酸处理后,再加入蔗糖碳源经碳化和除硅处理合成出有序介孔碳。该方法与传统硬模板相比,其合成工序简单,成本更低;与其他简化合成方法相比,避免了由碳源不足而造成的介孔碳有序性低的缺点。通过小角XRD、N2吸脱附和HRTEM对样品及其中间过程进行了表征。结果表明,自晶化过程后,样品在合成的各个时期均保持着有序的介孔结构,当蔗糖添加量为1.5g时合成出的介孔碳材料有序性最高,比表面积和孔容也最高,分别为1261m2·g-1,1.03cm3·g-1。