Structure and Processing Properties of Nine Yam (Dioscorea opposita Thunb) Starches from South China: A Comparison Study

In order to explore the processing and application potential of Chinese yam starch, nine kinds of Chinese yam starch (GY11, GY5, GY2, GXPY, LCY, SFY, MPY, SYPY, ASY) from South China were collected and characterized. The chemical composition, rheological properties, thermal properties, and in vitro starch digestion were compared, and the correlation between the structure and processing properties of these yam starches was analyzed using Pearson correlation. The results show that GY2 had the highest amylose content of 28.70%. All the yam starches were similarly elliptical, and all the yam starch gels showed pseudoplastic behavior. Yam starches showed similar pasting temperatures and resistant starch content, but SYPY showed the largest particle size (28.4 μm), SFY showed the highest setback (2712.33 cp), and LCY showed the highest peak viscosity (6145.67 cp) and breakdown (2672.33 cp). In addition, these yam starches also showed different crystal types (A-type, B-type, C-type), relative crystallinity (26.54–31.48%), the ratios of 1045/1022 cm⁻¹ (0.836–1.213), pasting properties, and rheological properties, so the yam starches have different application potentials. The rheological and pasting properties were related to the structural properties of starch, such as DI, Mw, and particle size, and were also closely related to the thermodynamic properties. The appropriate processing methods and purposes of the processed products of these yam starches can be selected according to their characteristics.     

用自动凯氏定氮仪测定水中氨氮

用MgO控制预蒸馏水中的pH值,以硼酸溶液为吸收液,用稀硫酸进行中和滴定,用自动凯氏定氮仪测试水中的氨氮,检测下限为1mg/L,相对标准偏差在0.32%~1.04%范围内,加标回收率为96%~104%,并将该法与纳氏试剂比色法和离子色谱法进行了比较。     

浅谈黄原胶及其在农药制剂加工中的应用

黄原胶是极具发展潜力的生物多糖,独特的分子结构使其具有良好的增稠、乳化和稳定作用,已被广泛应用于日用化工、石油开采、纺织印染、食品、医药、涂料、农药等众多工业领域,拥有广阔的市场前景。本文对黄原胶的结构、特性、生产工艺以及主要应用领域等进行了简单综述,总结了黄原胶在农药制剂加工中的应用现状,指出黄原胶优越的流变特性对悬浮剂、水乳剂、悬乳剂等农药制剂悬浮稳定性的提高具有重大意义,最后展望了黄原胶未来的发展前景。     

Sample Entropy as a Tool to Assess Lumbo-Pelvic Movements in a Clinical Test for Low-Back-Pain Patients

Low back pain (LBP) obviously reduces the quality of life but is also the world’s leading cause of years lived with disability. Alterations in motor response and changes in movement patterns are expected in LBP patients when compared to healthy people. Such changes in dynamics may be assessed by the nonlinear analysis of kinematical time series recorded from one patient’s motion. Since sample entropy (SampEn) has emerged as a relevant index measuring the complexity of a given time series, we propose the development of a clinical test based on SampEn of a time series recorded by a wearable inertial measurement unit for repeated bending and returns (b and r) of the trunk. Twenty-three healthy participants were asked to perform, in random order, 50 repetitions of this movement by touching a stool and another 50 repetitions by touching a box on the floor. The angular amplitude of the b and r movement and the sample entropy of the three components of the angular velocity and acceleration were computed. We showed that the repetitive b and r “touch the stool” test could indeed be the basis of a clinical test for the evaluation of low-back-pain patients, with an optimal duration of 70 s, acceptable in daily clinical practice.     

热分析动力学数据处理方法的研究进展

综述了最近几年来用热分析法研究固相反应动力学的数据处理方法的新进展,指出了现有方法的成功与局限性,介绍了几种新的动力学处理方法及一种新的热分析技术。     

基于小波的恒电量瞬态响应信号的滤波处理

利用小波变换的阈值法对恒电量响应信号进行滤波处理, 同时与传统的时域和频域的滤波方法进行分析比较, 并且讨论了小波变换的分解层数对恒电量响应信号滤波效果的影响. 结果表明, 利用小波变换可以在时域和频域同时对恒电量响应信号取得良好的去噪效果. 这不仅能提高时域曲线拟合的精度, 还大大地提高了恒电量频谱解析的可靠性. 在实际应用中, 小波变换的分解层数取5～7层可以收到满意的效果.     

苦杏仁的炮制及有效成分提取和分析进展

苦杏仁为常用中药,用途广泛,人们对其研究热潮方兴未艾．本文介绍了苦杏仁的炮制及有效成分提取和分析进展,引用文献55篇．     

Optimization of the Production of Thermostable endo-β-1,4 Mannanases from a Newly Isolated <Emphasis Type="Italic">Aspergillus niger gr</Emphasis> and <Emphasis Type="Italic">Aspergillus flavus gr</Emphasis>

The aim of this work was to establish optimal conditions for the maximum production of endo-β-1,4 mannanases using cheaper sources. Eight thermotolerant fungal strains were isolated from garden soil and compost samples collected in and around the Gulbarga University campus, India. Two strains were selected based on their ability to produce considerable endo-β-1,4 mannanases activity while growing in liquid medium at 37 °C with locust bean gum (LBG) as the only carbon source. They were identified as Aspergillus niger gr and Aspergillus flavus gr. The experiment to evaluate the effect of different carbon sources, nitrogen sources, temperatures and initial pH of the medium on maximal enzyme production was studied. Enzyme productivity was influenced by the type of polysaccharide used as the carbon source. Copra meal defatted with n-hexane showed to be a better substrate than LBG and guar gum for endo-β-1,4 mannanases production by A. niger gr (40.011 U/ml), but for A. flavus gr (33.532 U/ml), the difference was not significant. Endo-β-1,4 mannanases produced from A. niger gr and A. flavus gr have high optimum temperature (65 and 60 °C) and good thermostability in the absence of any stabilizers (maintaining 50% of residual activity for 8 and 6 h, respectively, at 60 °C) and are stable over in a wide pH range. These new strains offer an attractive alternative source of enzymes for the food and feed processing industries.     

Surface chemistry and electronics of semiconductor–nanosystem junctions I: metal-nanoemitter-based solar cells

Photoelectrochemically prepared nanotopographies on semiconductors are used for realization of nanoemitter solar devices that are active in the photovoltaic and the photoelectrocatalytic mode. The development of solar devices by a nonlinear electrochemical process and combined chemical/electrochemical metal deposition is described. Based on this low-temperature scalable approach, first efficiencies of 7.3% in the photovoltaic mode are reported for the photoelectrochemical solar cell n-Si/SiO₂/Pt/I₃ ⁻–I⁻. With p-Si/Pt nanocomposite structures, light-induced H₂ evolution is achieved. The surface chemistry and morphology is analyzed by photoelectron spectroscopy (PES), Fourier transform infrared spectroscopy, and high-resolution scanning electron microscopy. The operational principle of Pt-based nanoemitter solar devices that use silicon single crystal absorbers is analyzed by Mott–Schottky plots, chronoamperometric profiles, and PES. Related to simultaneous oxide formation during Pt deposition, evidence for the formation of a metal–oxide–semiconductor junction is obtained that explains the observed electronic behavior. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical/Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September 2007.     

Development and characterization of a magnetic bead-quantum dot nanoparticles based assay capable of Escherichia coli O157:H7 quantification

The development and characterization of a magnetic bead (MB)-quantum dot (QD) nanoparticles based assay capable of quantifying pathogenic bacteria is presented here. The MB-QD assay operates by having a capturing probe DNA selectively linked to the signaling probe DNA via the target genomic DNA (gDNA) during DNA hybridization. The signaling probe DNA is labeled with fluorescent QD₅₆₅ which serves as a reporter. The capturing probe DNA is conjugated simultaneously to a MB and another QD₆₅₅, which serve as a carrier and an internal standard, respectively. Successfully captured target gDNA is separated using a magnetic field and is quantified via a spectrofluorometer. The use of QDs (i.e., QD₅₆₅/QD₆₅₅) as both a fluorescence label and an internal standard increased the sensitivity of the assay. The passivation effect and the molar ratio between QD and DNA were optimized. The MB-QD assay demonstrated a detection limit of 890 zeptomolar (i.e., 10⁻²¹ mol L⁻¹) concentration for the linear single stranded DNA (ssDNA). It also demonstrated a detection limit of 87 gene copies for double stranded DNA (dsDNA) eaeA gene extracted from pure Escherichia coli (E. coli) O157:H7 culture. Its corresponding dynamic range, sensitivity, and selectivity were also presented. Finally, the bacterial gDNA of E. coli O157:H7 was used to highlight the MB-QD assay's ability to detect below the minimum infective dose (i.e., 100 organisms) of E. coli O157:H7 in water environment.