以Pb-(BrO_3~-/Br~-)为媒介间接电氧化合成双醛淀粉

应用间接氧化法,以Pb为阳极,BrO3-/Br-为氧化媒介,电氧化淀粉制备双醛淀粉.研究了温度、硫酸与淀粉浓度对电合成过程的影响.在35℃,阳极液WNaBr=2%,CH2SO4=0.05 mol/L,W淀粉=10%,电流密度15 mA/cm2的实验条件下,电流效率为50%.     

Melting Processing of Biodegradable Cellulose Diacetate/Starch Composites

Natural polymers and their derivatives are attracting increasing interest as promising biodegradable materials that can meet the environmental and recycling demands from society. This study prepared biodegradable composites of cellulose diacetate and starch, and examined their physical and thermal properties. In addition, the morphology of the composites was examined by scanning electron microscopy. For melt processing, epoxidized soybean oil, as a lubricant, and triacetine, as a plasticizer, were added to the composites. The optimal conditions for the preparation of the biodegradable composites were determined. Increasing the amount of starch in the composites resulted in further enhancement of the processability of cellulose diacetate. The tensile strength and Young's modulus decreased, and the amount of elongation and T_g value increased with increasing amount of starch.     

改性塑制餐盒的好氧真菌降解及可堆肥性

采用好氧真菌降解和受控堆肥化试验分别测试了 3种改性塑制餐盒的生物降解性及可堆肥性 .试验结果显示 ,聚苯乙烯 -淀粉共混餐盒的生物降解性与其淀粉添加量密切相关 ,并且餐盒中淀粉的生物降解率随其添加量的减少而降低 .热塑性淀粉餐盒易于生物降解 ,其生物降解率可达 6 7.0 % .这种餐盒具有良好的可堆肥性 ,经堆肥化处理后能被完全消纳 .     

The Thermal Stability and Rheological Properties of Alkylated Carboxymethyl Starch

Several alkylated carboxymethyl starches (CMS) with different alkyl chain lengths were prepared. The influence of the number of alkyls on the thermal stability and rheological properties, such as thickening properties, salt-tolerance, temperature sensitivity and time-dependent rheological behavior, are discussed. The initial decomposition temperature (IDT) of alkylated CMS reached 263°C ～293°C which, as compared to the IDT for CMS itself (230°C), indicated that the thermal stability of CMS was improved after being alkylated. The solution viscosities of the alkylated carboxymethyl starch increased with the increasing of alkyl length. With the alkyl chain length increasing from C₂ to C₈, the viscosity increased from 400 mPa·s to 38000 mPa·s. The weak hydrophobic aggregation of the alkyl groups did not improve the shear-resistance and relative hysteresis area. But the temperature sensitivity of alkylated CMS was improved as the chain length of the alkyl groups increased, as the activation energy (E_a) value decreased from 2.082 kJ·mol^?1 to 0.077 kJ·mol^?1; Improving the rigidity of the molecular chains and reducing the network structure of the hydrophobic contribution to the viscosity of the solution are benefits for improving the salt-tolerance and shear-resistance of the aqueous solution.     

Large Cyclodextrins

The existence of large cyclodextrins, cyclic -D-(1 4) glucans with a degree of polymerisation higher than eight, has been proven during the past decade. A number of 4- -glucanotransferases have been shown to be able to produce large cyclodextrins consisting of up to several hundred glycosyl units, from both amylose and amylopectin. Large cyclodextrins with degree of polymerisation up to 31 have been isolated to purity by use of elaborate purification schemes, enabling studies of their structural and complex forming properties. The solid state structures of the large cyclodextrins with a degree of polymerisation 10, 14 and 26, respectively, have revealed interesting new structural features of this family of molecules. This review summarises the studies of the large cyclodextrins, a varied and highly interesting group of molecules.     

Development of Certified Reference Materials for the Determination of Apparent Amylose Content in Rice

Apparent amylose content (AAC) is one of the most important parameters in rice quality evaluation. In this study, four rice reference materials used to test rice AAC were developed. The AAC of rice reference materials were measured by a spectrophotometric method with a defatting procedure, calibrated from potato amylose and waxy rice amylopectin at the absorption wavelengths of 620 and 720 nm. Homogeneity test (n = 20) was judged by F-test based on the mean squares of among and within bottles, and short- and long-term stability monitoring was performed by T-test to check if there was significant degradation at the delivery temperature of under 40 °C (14 days) and at 0–4 °C storage condition (18 months), respectively. After joint evaluation by ten laboratories, Dixion and Cochran statistical analyses were presented. The expanded uncertainties were calculated based on the uncertainty of homogeneity, short- and long-term stability, and inter-laboratory validation containing factor k = 2. It found that the four reference materials were homogenous and stable, and had the AAC (g/100 g, k = 2) of 2.96 ± 1.01, 10.68 ± 0.66, 17.18 ± 1.04, and 16.09 ± 1.29, respectively, at 620 nm, and 1.46 ± 0.49, 10.44 ± 0.56, 16.82 ± 0.75, and 24.33 ± 0.52, respectively, at 720 nm. It was indicated that 720 nm was more suitable for the determination of rice AAC with lower uncertainties. The determinations of the AAC of 11 rice varieties were carried out by two methods, the method without defatting and with calibration from the four rice reference materials and the method with a defatting procedure and calibrating from potato amylose and waxy rice amylopectin. It confirmed that the undefatted rice reference materials could achieve satisfactory results to test the rice samples with the AAC ranging from 1 to 25 g/100 g. It would greatly reduce the time cost and improve testing efficiency and applicability, and provide technical support for the high-quality development of the rice industry.     

Beneficial Effect of Kidney Bean Resistant Starch on Hyperlipidemia—Induced Acute Pancreatitis and Related Intestinal Barrier Damage in Rats

Accumulating attention has been focused on resistant starch (RS) due to its blood-lipid-lowering activities. However, reports on the potential bioactivities of RS for preventing hyperlipidemia acute pancreatitis (HLAP) are limited. Therefore, in this study, an acute pancreatitis model was set up by feeding a hyperlipidemia diet to rats, and subsequently evaluating the anti-HLAP effect of RS in kidney beans. The results show that the IL-6, IL-1β, and TNF-α of serum in each RS group were decreased by 18.67–50.00%, 7.92–22.89%, and 8.06–34.04%, respectively, compared with the model group (MOD). In addition, the mRNA expression of tight junction protein ZO-1, occludin, and antibacterial peptides CRAMP and DEFB1 of rats in each RS group increased by 26.43–60.07%, 229.98–279.90%, 75.80–111.20%, and 77.86–109.07%, respectively. The height of the villi in the small intestine and the thickness of the muscle layer of rats were also increased, while the depth of the crypt decreased. The present study indicates that RS relieves intestinal inflammation, inhibits oxidative stress, and prevents related intestinal barrier damage. These results support the supplementation of RS as an effective nutritional intervention for HLAP and associated intestinal injury.     

Solvothermal synthesis of CdS nanorods using hydroxyethyl cellulose as a template

CdS nanorods were solvothermally produced from Cd(CH₃COO)₂ and S powder using ethylenediamine (en) as a solvent and hydroxyethyl cellulose (HEC) as a template. The phase with hexagonal structure was detected using XRD and SAED, which is in perfect accordance with the results obtained by simulation. SEM, TEM and HRTEM revealed the development of nanorods with a number of atoms arranged in crystal lattices. When the appropriate amount of HEC was used, the longest nanorods, with preferential growth in the [0 0 1] direction, were produced. Raman spectra showed the fundamental and overtone modes at the same wavenumbers of 301 and 599 cm⁻¹, respectively. Their relative intensities at each temperature were strongly influenced by the anisotropic geometry of the products. Photoluminescence caused by electron-hole recombination was detected at 470 nm, and by surface trapping induced emission at 575 nm. The formation mechanism of CdS nanorods was also proposed based on the experimental results.     

淀粉与丙烯酸甲酯的接枝共聚物作为生物降解塑料的研究

如何解决废弃塑料制品的再资源化和使用无污染的降解塑料是当今人类急待解决的热点课题．淀粉与丙烯酸甲酯（MA）进行接技共聚以制备塑料发泡产品的研究已有报道［‘－‘1，一般认为塑料中淀粉含量在40％以上的产品，很容易在土壤中被微生物降解掉［‘］．这些研究都是在水溶液体系中进行的，本文的目的在于开发高淀粉含量的接校共聚物，为此对比了在3种不同体系（MA－CH3OHA12O三元均相溶液体系，水溶液体系和乳液体系）中得到的接校共聚物的力学性能、形态观察与组成情况，发现单纯追求高接技效率与接枝链MA的高分子量并不一定能得到…     

农村中学就地取材制作盐桥的实验研究

分别用可溶性淀粉、食用红苕淀粉、面粉、果胶粉、香蕉泥及土豆泥代替琼脂制作离子传导的介质,并对不同材料所制得的“盐桥”进行对比研究。实验结果表明,可溶性淀粉制作的盐桥的离子传导性能可与琼脂媲美。因此,可溶性淀粉是除琼脂外另一个制作盐桥的理想材料。实验结果为农村中学进行化学实验教学提供参考。