Purification and characterization of antioxidative peptides derived from rice bran protein hydrolysates

Rice bran protein fraction (RBPF)—albumin, globulin, glutelin and prolamin were hydrolyzed with proteases M, N, P, S and pepsin under their optimal conditions for 24 h. Hydrolysates of various hydrolysis periods were collected and subjected to peptide mapping and the antioxidative activity measured by the 2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic Acid (ABTS) method. Protease M hydrolysates showed high degree of hydrolysis (DH), but low antioxidative activity. On the contrary, pepsin hydrolysates showed low DH with high activity. Albumin and globulin hydrolysates had higher DH values, but lower values for glutelin and prolamin. The globulin hydrolysate (Opep2) from 2 h-pepsin hydrolysis was separated by using three consecutive purification steps with RP-HPLC. Nineteen antioxidative peptides were isolated and their amino acid sequences were determined by a gas-phase protein sequencer and MALDI-TOF mass spectrometry. These peptides were composed of 6–30 amino acid residues with molecular masses ranging from 670–3,611 Da. Tyr-Leu-Ala-Gly-Met-Asn had the highest antioxidative activity among them.     

Conversion kinetics of container glass batch melting

Understanding the batch-to-glass conversion process is fundamental to optimizing the performance of glass-melting furnaces and ensuring that furnace modeling can correctly predict the observed outcome when batch materials or furnace conditions change. To investigate the kinetics of silica dissolution, gas evolution, and primary foam formation and collapse, we performed X-ray diffraction, thermal gravimetry, feed expansion tests, and evolved gas analysis of batch samples heated at several constant heating rates. We found that gas evolving reactions, foaming, and silica dissolution depend on the thermal history of the batch in a similar manner: the kinetic parameters of each process were linear functions of the square root of the heating rate. This kinetic similarity reflects the stronger-than-expected interdependence of these processes. On the basis of our results, we suggest that changes in furnace operating conditions, such as firing or boosting, influence the melting rate less than what one would expect without consideration of batch conversion kinetics.     

Microstructure and superconducting properties of rapidly-quenched copper-based alloys containing immiscible lead and bismuth elements

Copper-based superconducting alloys including finely dispersed f c c lead or h c p (Pb- Bi) particles in f c c copper matrix have been obtained by rapid quenching (Cu-M)_100-x Pb_x and (Cu-M)_100-x (Pb_0.6Bi_{0.4 x} (M = aluminium, silicon or tin;x < 10 at%) alloys containing immiscible elements such as lead and bismuth. The particle size and interparticle distance were about 30 to 130 nm and 20 to 200 nm for had particles and about 30 to 60 nm and 30 to 150 nm for (Pb- Bi) particles. The transition temperature,T _c, was in the range of 3.2 to 5.5 K for the Cu-M-Pb alloys and 6.2 to 6.3 K for the Cu-M-Pb-Bi alloys. Critical magnetic field,H _c2, and critical current density,J _c, for the later alloys were 0.47 to 0.93T at 4.2 K and 1.1 × 10⁵ to 2.7 × 10⁵ Am^–2 at zero applied field and 4.21 K. The mechanism of the appearance of such a soft-type superconductivity for the rapidly quenched copper-based alloys was discussed, and inferred to be due to the formation of a percolation path of a superconducting lead or Pb-Bi phase along the grain boundaries, sub-boundaries and/or tangled dislocations where the lead or Pb-Bi phase precipitated preferentially, rather than the proximity effect based on lead or Pb-Bi particles.     

Amino acid sensing by impedance of porous monolith-type ion exchanger

A biological and chemical sensor with rapid response at the microlevel is required for health and environmental monitoring. To develop a high-performance sensor, we use a porous monolith-type ion exchanger having three-dimensional acceptors to sense chemical substances. This porous monolith-type ion exchanger has an open-cellular structure with 5-50-μm diameter pores. The concentration of amino acids in the solution can be detected by measuring the impedance of the monolith-type ion exchanger. The novel ion exchanger has a high-exchange rate and high-electrical conductivity compared with that of the conventional ion-exchange resins. It is found that the impedance of the porous ion exchanger varies widely, depending on the amino acids such as glycine, asparatic acid, lysine, and phenylalanine. The impedance of anion exchanger had the highest value for phenylalanine with a benzene ring. OH-ion conduction is suppressed possibly due to the phenylalanine molecules stabilized by the hydrophobic interaction with the anion exchanger. In addition, we succeeded in sensing amino acid ions with concentration as low as 10⁻⁷ mol. The porous ion exchanger has the potential of a high-performance device for biological and chemical sensing.     

Analysis of Mg content of Zn_(1-x)Mg_xO film grown on sapphire substrates by plasma-assisted molecular beam epitaxy

Semiconductor materials with wide band gap have been extensively used to fabri-cate the blue laser light emitting diodes and ultraviolet photodetectors, which are impor-tant elements of semiconductor instruments, such as displays, optical data storages, ul-traviolet sensors, electroluminescent devices and solar-blind detectors. This kind of ma-terials is now becoming a hot research object in semiconductor physics. GaN was the first suitable ultraviolet laser material people found in this real…     

液氧集中供气新技术

本文介绍了一种新型的液氧集中供气技术,阐述了该系统主要设备的技术参数选择、性能、安全使用和维护保养等问题。     

Colorless polyimides with low coefficient of thermal expansion derived from alkyl‐substituted cyclobutanetetracarboxylic dianhydrides

Alkyl‐substituted cyclobutanetetracarboxylic dianhydrides (CBDAs) were synthesized by photo‐dimerization of alkyl‐substituted maleic anhydrides to obtain novel colorless polyimides (PIs). Dimethyl‐substituted CBDA (DM‐CBDA) showed much higher polymerizability with various diamines than conventional cycloaliphatic tetracarboxylic dianhydrides and led to high molecular weights of PI precursors. Polyaddition of non‐substituted CBDA and trans‐1,4‐cyclohexanediamine (t‐CHDA) was completely inhibited by salt formation in the initial reaction stage. The use of DM‐CBDA allowed the formation of a homogeneous/viscous PI precursor solution by overcoming the salt formation problem. The prominent substituent effect probably reflects how the methyl substituents of DM‐CBDA contributed to increasing the salt solubility. Some of the thermally imidized DM‐CBDA‐based systems simultaneously possessed non‐coloration, low coefficient of thermal expansion (CTE), very high T_g exceeding 300 °C and very low dielectric constant. Copolymerization was very effective for improving the solubility of DM‐CBDA‐based PIs. The copolyimide cast films prepared via chemical imidization displayed a further decreased CTE without sacrificing other target properties, suggesting that the present materials can be useful as plastic substrates in display devices. The mechanism of self‐chain orientation behavior during solution casting is also discussed. A potential application of the copolyimide systems as optical compensation film materials in liquid crystal displays is proposed. © 2013 Society of Chemical Industry .     

Tensile strained QW structure for low-threshold operation of short-wavelength, AlGaInP LDs emitting in the 630 nm band

The amount of tensile strain introduced into QWs and the optimum QW structure are evaluated for low-threshold operation of AlGaInP LDs in the wavelength range 630-640 nm. Very low threshold current of 32 mA under CW operation at 20 degrees C is achieved in an index-guided SQW LD emitting at 632 nm.<>     

Fabrication of magnesium based composites reinforced with carbon nanotubes having superior mechanical properties

Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al₂MgC₂ compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition.     

The use of a virtual city model for assessing equity in access to views

The development of virtual city models has provided novel possibilities for analyses that require consideration of building heights in urban areas. The study was undertaken to explore these possibilities by using the virtual Kyoto model to examine equity in access to views in the Japanese city. A sample of just over 5000 residences was selected by stratifying for population age and affluence. A series of viewsheds were computed to quantify the visibility of a range of environmental amenities (greenspaces, water bodies, historical buildings, mountains) and disamenities (factories and roads). Evidence of inequity in visual amenity was identified, whereby homes in areas with many old people were much less likely to have views of greenspaces and water bodies, although they were also less likely to see factories and roads and were more likely to view mountains. Homes in more affluent areas had better views of greenspaces, historical buildings, and mountains, and were less likely to see factories and water bodies. We discuss the potential of virtual city models for furthering analyses of the urban environment and raise some caveats regarding their use.