The Impact of Thermal Events on Amylose‐Fatty Acid Complexes

The molecular behavior of amylose‐lipid complexes was studied using differential scanning calorimetry. rapid viscoanalysis and texture analysis methods. Three amyloses were fractionated, one each from regular, 50% amylose and 70% amylose corn starches. High performance size exclusion chromatography, coupled with multiple angle laser light scattering, was used to determine amylose molecular weight profiles; fractions differed statistically (P>0.05) in their z‐average molecular weights (M_z). Each amylose fraction was complexed with five different fatty acids. After 12 days of storage, amylose‐lipid complexes had recrystallization percentages ranging from 42.7 to 98.2%. Cohesiveness (r = ‐0.84) and adhesiveness (r = ‐0.75) decreased with increasing M_z of amyloses (P>0.05). An inverse relationship was obtained between fatty acid chain length and percent recrystallization (r = ‐0.84, P>0.05). Percent recrystallization decreased when fatty acid chain length increased from C16:0 to C18:0. All complex samples, when adjusted to an equal total starch basis, had decreased viscosities when pasted compared to their native starch or amylose counterparts. Shear thinning of complexes increased with increasing molecular weight (M_z) of amyloses (r = 0.71, P>0.05). Lower recrystallization rates and decreased viscosity properties could be accomplished complexing by amylose and fatty acids.     

Convergence of threshold networks using their dissipative system model

A new dynamical energy system model representation is given for threshold networks. Inspired by the relation between stability and dissipativeness of dynamical systems, the convergence property of threshold networks is investigated. Using the energy function inherent within the given model a condition, namely the dissipativeness of the dynamical system, necessary and sufficient condition for the convergence of the threshold network to a fixed point, is given. Also, an easy to check inequality is stated to test the convergence of the threshold network. Copyright © 2000 John Wiley & Sons, Ltd.     

长丝的工艺优化

天然纤维的应用虽已有数千年历史,但仍无法满足当今世界人口的需求,所以合成纤维的发明无疑是20世纪最重要的发明之一。另一个重点是纺织行业的竞争,为了不断满足客户的新要求,长丝的生产工艺和其特性得到了多方面的改进,因而长丝工业也变得越来越重要。主要介绍了对长丝质量变化进行的测试和测试结果的分析。     

New Magnesium Composite with Mg17Al12 Intermetallic Particles

Powder Metallurgy and Metal Ceramics - Although magnesium is one of the materials with the lowest density, its application is limited amongst other commercial materials due to insufficient...     

A case study of a stress corrosion cracking failure in an AA5083 mold material used for curing rubber compounds

Protection of Metals and Physical Chemistry of Surfaces - In this study the failure analysis of an AA5083 mold material, used for curing rubber compounds, was carried out. The problem revealed...     

Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes.     

Precursor route poly(thienylene vinylene) for organic solar cells: Photophysics and photovoltaic performance

Photophysical studies and photovoltaic devices on a low bandgap, high-charge carrier mobility poly(thienylene vinylene) (PTV), prepared from a soluble precursor polymer synthesised via the “dithiocarbamate route”, are reported. In composites with an electron acceptor ([6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM), a soluble fullerene derivative), photoinduced absorption characteristic for charged excitations together with photoluminescence quenching are observed indicating photoinduced electron transfer. The “bulk heterojunction” photovoltaic devices using PTV and PCBM composites show short-circuit currents up to 4 mA/cm² under AM 1.5 white-light illumination. The photocurrent spectrum of the photovoltaic device shows an onset about 1.65 eV (750 nm), which corresponds to the absorption spectrum of the polymer.     

铜添加对近共晶Al-Si-xCu合金的微观组织和硬度的影响

研究铜含量对Al-Si-xCu（x=2%,3%,4%and5%）合金的微观组织和硬度的影响。不同铜含量的铝合金经熔炼后于690°C铸造成湿砂模并固化,于500°C保温7h进行固溶处理后对样品进行水冷。随后于190°C进行时效处理,分别保温5,10和15h,研究时效时间对基体硬度的影响。采用差热分析法,在冷却速度30K/min下确定平衡相的转变温度,并研究铜含量对四元共晶合金的形成和α（Al）＋Si熔点的影响。结果表明,随着铜含量的增加,发生析出硬化从而导致基体硬度增加,α（Al）＋Si的熔点降低,共晶相的含量增加。当铜含量超过2%时,生成熔点为507°C的四元共晶相。