应用阳离子交换树脂催化水解蔗糖──Ⅱ.蔗糖水解最佳反应条件选择

本文研究H+型强酸性阳离子交换树脂为蔗糖水解催化剂时，催化剂柱温、蔗糖进料浓度和空速等工艺条件对蔗糖水解的影响．结果表明，蔗糖在离子交换树脂柱内的较佳水解温度段为40～54℃；在相同蔗糖水解率下，空速随蔗糖进料浓度的增高而增高、较高的进料浓度有利于充分发挥催化剂效能；若适当降低蔗糖水解程度，可明显提高空速，提高生产率。     

Conformational aspects of the solvation of polyhydroxy compounds in binary mixtures of N,N-dimethylformamide and water

Enthalpies of solution of -D-fructose and sucrose in binary solvent mixtures of water and N,N-dimethylformamide (DMF) at 25°C over the whole mole fraction region are reported and compared to those of -D-glucose. Because in these solvent systems the mutarotation of -D-fructose is fast and accompanied by large enthalpy changes, the measured enthalpies of solution of this compound had to be corrected for this effect. The dependences of the enthalpies of solution on the composition of the solvent mixtures are considered to result from preferential hydrogen-bonding of the hydroxyl groups and hydrophobic hydration of the apolar parts of the surface of the solute molecule. Distinctions between the enthalpy of transfer curves are discussed in terms of conformational differences and additivity aspects in the solvation behavior of the compounds. The predominance of furanose forms of fructose in DMF and that of pyranose forms of the same solute in water are related to differences in solvation.     

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.     

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.     

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。     

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.     

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.     

高效阴离子交换色谱-脉冲安培检测法测定烤烟中的水溶性葡萄糖、果糖和蔗糖

用高效阴离子交换色谱-脉冲安培检测法（HPAEC-PAD）测定了烤烟中的水溶性葡萄糖、果糖和蔗糖。采用水浸取及膜过滤法处理烤烟样品,以Dionex CarboPac PA-1阴离子交换柱为色谱柱,0.2 mol/L NaOH水溶液为淋洗液进行分离测定。葡萄糖、果糖和蔗糖的含量与其峰面积的线性关系良好,回收率均在97%以上。方法简便易行,灵敏度高,重现性良好,可以实现对烟草中单糖的快速分离和测定。