Reversible Molecular Rearrangement of Slightly Acid-treated Starches

The reersible association and dissociation of starch chain populations obtained from acid-treated starches (ATSs) was investigated. Potato starch, both nonglutinous and glutinous rice starches and sago starch were suspended in 15% sulfuric acid until 1% hydroysis occured. These ATSs had relative molecular weight ranges of 25,00–29,000 daltons. In water, about half the molecules were reconstituted into large aggregates of a few million daltons. This change in molecular size depended on presence of potassium chloride. It was not observed in debranched samples. The aggregates showed a clear endothermic peak on a DSC curve. Thus, the reversibly rearranging starch chain populations were not linear, but were branched and had some type of ordered structure.     

超高效液相-串联四极杆质谱联用法同时测定并比较甘草各部位中8种成分含量

建立同时检测甘草中8种成分:22-羟基-甘草次酸、3-epi-甘草次酸、甘草次酸、甘草酸、甘草苷、芒柄花黄素、异甘草酚、甘草香豆素的超高效液相色谱-串联四极杆质谱联用法。选用胆酸作为三萜成分的内标,相思子素2"-O-β-芹菜糖苷作为酚类化合物的内标。甘草样品经粉碎用甲醇(含内标液)超声提取,采用安捷伦ZORBAX RRHD C18柱(50 mm×2.1 mm,1.8μm),以甲醇-0.1%甲酸溶液为流动相,梯度洗脱,以电喷雾电离源,采用超高效液相-串联四极杆质谱联用动态多反应监测模式测定。结果表明,8种成分检出限均小于0.048 8μg/mL,定量限均小于0.195 2μg/mL,在0.048 8~12.500 0、0.048 8~12.500 0、0.012 2~12.500 0、0.048 8~50.000 0、0.048 8~50.000 0、0.012 2~12.500 0、0.012 2~15.000 0、0.195 2~12.500 0μg/mL范围内,22-羟基-甘草次酸、3-epi-甘草次酸、甘草次酸、甘草酸、甘草苷、芒柄花黄素、异甘草酚、甘草香豆素的峰面积与质量浓度呈良好线性关系,相关系数均大于0.99;方法回收率为97.2%~113.0%间;其日内及日间精密度实验的相对标准偏差分别为2.63%~4.47%及1.75%~3.72%。该方法灵敏度高、稳定性强、操作简便、快捷、准确,可用于甘草各部位及其相关食品质量控制。     

Functional Improvement of Alginic Acid by Conjugating with β-Lactoglobulin

Two bovine β-lactoglobulin-alginic acid (β-LG-ALG) conjugates were prepared to improve the function of ALG by using water-soluble carbodiimide and the Maillard reaction. Fluorescence studies suggested that the conformation around Trp had been changed in each conjugate and that the surface of each conjugate was covered with polysaccharide chain. Structural analyses with monoclonal antibodies indicated that the conformation around 15Val-29IIe (β -sheet) in each conjugate had changed, while the native structure was maintained around 125Thr-135Lys (α-helix). After conjugating with β -LG, ALG showed retinol-binding and high emulsifying ability. The aggregating property of ALG in acid and in the presence of Ca²⁺ was improved in each conjugate.     

用微波等离子体改性氟树脂表面

我们发现了用微波炉产生的微波来很简单地进行等离子体处理的新方法。用这种方法处理了聚四氟乙烯(PTFE)和四氯乙烯-六氟丙烯共聚物(FEP)。为了评价等离子体处理了的高分子的润湿特性。用了苯二甲酸二烷酯(DAP)作接触角测定的标准液体。由DAP在聚丙烯上的接触角(θ)根据Fowkes方程求出了DAP的表面张力的色散力成分(γ_L~d)及极性成分(γ)。等离子体处理后,标准液体在 FEP和 PTFE上的cosθ增大,而且γ_L(1+cosθ)/(γ_L~d)~(1/2)与(γ_L~P)~(1/2)/(γ_L~d)~(1/2)之间成直线关系。等离子体处理后的FEP和PTFE的γ_3,γ_5~d,γ_s~P都有所增加。ESCA分析结果显示,经等离子体处理后,有相当量的氧导入了高分子表面。粘合到等离子体处理了的FEP和PTFF上的压敏胶带的剥离强度增加到未处理时的约2～3倍。     

LOCALIZATION OF PARATROPOMYOSIN IN CHICKEN SKELETAL MUSCLE MYOFIBRILS AND ITS BEHAVIOR DURING POSTMORTEM STORAGE OF MUSCLES REVEALED BY IMMUNOELECTRON MICROSCOPY

Paratropomyosin is a minor myofibrillar protein which in freshly prepared myofibrils is exclusively localized at the A-I junction region of sarcomeres. We investigated the ultrastructural localization of paratropomyosin in intact and postrigor myofibrils by immunoelectron microscopy. Paratropomyosin was localized as two distinct stripes at the A-I junction in intact myofibrils. It also was localized at the position corresponding to the original A-I junction in thick filament-free myofibrils (I-Z-I brushes). However, following postmortem storage, paratropomyosin was found broadly distributed in thin filaments of myofibrils.     

预应变对不同含碳量钢材疲劳特性的影响

通过对非预应变15号、35号和45号钢及其各种预应变材料进行实验,研究了预应变量对不同含碳量钢材疲劳强度和疲劳裂纹发生的影响。实验结果表明:在相同的预应变预量的条件下,材料的疲劳极限随含碳量的增加而提高;当预应变量较低时,预应变材料的疲劳极限低于非预应变材料,含碳量越高降低的程度越明显;当预应变量较高时,材料的疲劳极限随预应变量的增加而恢复或提高。     

Edible Meat Casing from Reconstruction of Collagen-Elastin Matrix

Pepsin-solubilized clastin (PSE) was prepared from insoluble elastin (IE) preparation by digesting it with pepsin [IE:pepsin, 100:1(w/w)] at 25°C for 5–30 hr prior to dialyzing against water and lyophilizing. PSE showed amino acid compositions similar to that of IE and relative molecular weight (Mr) of 6–640 × 10³. PSE accelerated the matrix reconstruction of pepsin-solubilized collagen (PSC) and reduced the rcdissolution of the PSC matrix under several solvent conditions. PSE clcvatcd the matrix thermal dcnaturation temperature from about 50°C to 55°C, leading to decreased breaking strength and reduced elongation of the PSC film, as compared with the control.     

Deadbeat Control with Disturbance Compensation Method and 1 MHz‐PLL for Single Phase Utility Interactive Inverter

In the near future, many distributed power systems will be connected to utility lines in the local area. The demand for control accuracy of utility interactive inverters will likely increase beyond present capabilities. The utility interactive inverter requires FRT capability to compensate for utility voltage fluctuations. A deadbeat control with disturbance compensation and 1 MHz‐PLL control with quasi‐dq transformation were applied to a utility interactive inverter using an FPGA based hardware controller. The FRT characteristics were verified through simulations and experiments, and the superior characteristics of the proposed method were verified.     

Analysis of non-linear transmission lines by frequency domain perturbation method

We discuss a numerical method for solving non-linear transmission lines in the frequency domain. Such transmission lines are widely used for communications such as in GaAs integrated circuits and varactor diode circuits. The circuit equations are described by non-linear partial differential equations, so their analysis is very complicated compared with that of linear transmission lines. In this paper we propose a frequency-domain perturbation method for weakly non-linear transmission lines where the wave-forms are approximated by Fourier expansions and each frequency component is calculated by a modified perturbation method. To improve convergence, we introduce two new techniques, the compensation method and the homotopy method, which help to make the iteration stable and can be applied to a wide class of non-linear transmission lines. We have analysed shock wave phenomena in example. © 1997 by John Wiley & Sons, Ltd.