A Modulated Differential Scanning Calorimetric study

Modulated Differential Scanning Calorimetry^? has been applied to frozen sucrose solutions in the concentration range 10–80% w/w. The results from this study present, for the first time, information on the reversing and non-reversing nature of events that occur in these solutions. The study demonstrates the potential benefits of this new technique to help separate complex transitions that can occur in the total heat-flow curves obtained using traditional differential scanning calorimetry. The results illustrate how this new technique can separate the different enthalpic events, which relate to the glass transition and the onset of ice dissolution that occurs during the heating of these frozen systems, by nature of their “reversing” and “non-reversing” contributions to the total heat flow.     

Biosensor for determination of glucose and sucrose in fruit juices by flow injection analysis

Glucose and sucrose were measured with an amperometric method by using the flow injection analysis technique. A carbon paste electrode with a renewable surface containing glucose oxidase, horseradish peroxidase, and ferrocene was used in combination with the soluble enzymes invertase and mutarotase. The effect of invertase, mutarotase, and ascorbic acid on the electrode response was examined. Glucose and sucrose concentrations were determined with <3% errors. The proposed method for glucose and sucrose measurements was validated in real samples of fruitjuices. The results were also compared with those obtained with the ultraviolet method.     

Enzyme-catalyzed organic synthesis of sucrose and trehalose with in situ regeneration of UDP-Glucose

This paper describes cell-free enzymatic syntheses of sucrose and trehalose using partially-purified preparations of sucrose and trehalose synthetase. The coupling of the regeneration of uridine-5′-diphosphoglucose (UDP-Glc) with synthesis of the disaccharide offers a practical route to millimol quantities of these carbohydrates. The syntheses used pyruvate kinase, UDP-Glc pyrophosphorylase, and inorganic pyrophosphatase, and the regenerated UDP-Glc was cycled approximately 10 times. This work was supported by the NIH through several grants, most recently GM 30367.     

Isothermal diffusion studies of the H2O-sucrose-KCl system at 25°C

Diffusion coefficients were obtained for two compositions of the system H₂O-sucrose-KCl at 25°C. These plus published diffusion coefficients of the same system at two other compositions led to the construction of three-dimensional surface diagrams. Using these diagrams, the diffusion coefficients of the ternary system were compared with those of binary systems of components. The main diffusion coefficient of KCl was estimated from the conductivity data of KCl in aqueous solution of sucrose, and the agreement of these with experimental values was found to be satisfactory. The possible cause for the appreciable size of the cross-term diffusion coefficients is discussed.     

Preparation and Characterization of Titania Thin Films from Aqueous Solutions

Dip- or spin-coating and characterization of titania (TiO₂) thin films from various aqueous solutions have been studied. The aqueous titanium solutions mainly used in this study were halogen- and chelate-free solutions with the concentrations up to 1.4 M derived from titanium isopropoxide (TIP) with tetramethylammonium hydroxide (TMAOH) or some alkylamines, while aqueous and alcoholic solutions containing titanium atoms stabilized chelating ligands were examined for comparison. The TiO₂ films prepared from the TIP-TMAOH solution were already crystallized at 350°C to anatase form and those formed at 600°C had high transparency and refractive indices of 2.40. No carbon residue in the film prepared at 400°C was detected by XPS. The pure anatase form was sustained up to 850°C. Interestingly, it was found that the (004) preferentially oriented anatase films were obtained from TIP-lactic acid (LA) system until 700°C. The solutions containing citric acid (CA) or alkanolamines yielded anatase and rutile form fired at the temperatures equal to or higher than 600°C. Carbon residue was detected in the film fired at 400°C. The film thickness monotonically decreased from the upper to the bottom ends of the substrate. However, it was found that the thickness uniformity was drastically improved by an addition of sucrose to the aqueous solutions. The effects of the solution composition and polyhydroxy compounds on the crystal modifications of formed films and the film uniformity are discussed.     

丝氨酸在蔗糖水溶液中的稀释焓

利用LKB 2277生物活性检测仪分别测定了298.15 K时丝氨酸在不同组成的蔗糖水溶液中的稀释焓, 利用McMillan-Mayer理论,计算了丝氨酸在不同组成的蔗糖水溶液中的焓对相互作用系数,并与其在葡萄糖水溶液中的焓对相互作用系数h2进行了比较.结果表明,丝氨酸在蔗糖和葡萄糖水溶液中的焓对相互作用系数h2都是负值,并且随着糖浓度的增加,h2系数的绝对值逐渐减少.根据溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释.     

Effects of Some Hydrotropic Agents on the Formation of Indomethacin/β-Cyclodextrin Inclusion Compounds

The influence of the water structure promoters, mannitol and sucrose, on the indomethacin/-cyclodextrin inclusion process at different pH values was evaluated using the phase solubility method and circular dichroism spectroscopy. The effect of mannitol and sucrose on the total solubilizing activity of -cyclodextrin as well as on the stabilization of the complex was moderate, and depended strongly on the pH value of the medium. The most pronounced effect on the association constant of the indomethacin inclusion compound was observed in KCl/HCl buffer of pH 1.6, because mannitol and sucrose, in the absence of -cyclodextrin, approximately double the indomethacin solubility so that the constant value decreases. On the other hand, a very strong complex formation between indomethacin and -cyclodextrin was observed in acid medium (KCl/HCl buffer, pH = 1.6), a fact not much discussed in the literature. The apparent association constant of the inclusion compound formed in the absence of mannitol or sucrose was found to be of the same order of magnitude as for the complex formed at pH 6.8. Changes in the optical activity of the indomethacin/-cyclodextrin inclusion complex were registered in the presence of sucrose, which interacts more strongly than mannitol with water molecules, and could probably adhere to the surface of the inclusion complex, thus changing its configuration and environment.     

反丁烯二酸蔗糖甲酯的表面活性作用

本文报道了具有抑菌和乳化作用的双功能反丁烯二酸蔗糖甲酯(sucrose methyl fumarate,SMF)的合成。分子结构式示意如下。其中SUC表示蔗糖分子结构母体，n为蔗糖分子中羟基参与酯化的数目，即酯化度。它的抑菌性能和乳化性能均随其酯化度的变化而变化。本文研究抑菌作用较强的酯化度为5．5的SMF的表面活性作用。反丁烯二酸蔗糖甲酯的合成、表征及抑菌特性的研究另文报道。     

EPR Study of the Kinetics of the Formation of Radicals from Dibenzoyl Peroxide on Porous Glass

The kinetics of the formation of radicals from dibenzoyl peroxide supported on porous glass have been determined with EPR techniques over the temperature range of 25-100°C. Values of the activation energy of 18.5 and 25 kcal/mole have been observed for two differently prepared porous glass support materials.     

丙氨酸在蔗糖-水混合溶剂中的焓对相互作用

利用LKB2277生物活性检测仪测定了298.15 K时丙氨酸分别在不同组成的蔗糖- 水混合溶剂中的稀释焓,利用McMillan-Mayer理论,计算了丙氨酸在不同组成的蔗 糖-水混合溶剂中的焓对相互作用系数h_2,并与其在葡萄糖-水混合溶剂中的焓对 相互作用系数h_2进行了比较。结果表明,丙氨酸的h_2分别在葡萄糖和蔗糖的摩尔 分数为0.1009和0.05843处出现极大值,极值点位置的不同与糖分子所含羟基数目 的多少有关,根据溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释。