Biochemical changes in phosphorus compounds and in the activity of phytase and α-amylase in the rice (Oryza sativa) grain during germination

Changes in the phytic acid, inorganic phosphorus and ATP contents, and in the activity of phytase and α-amylase in rice (Oryza sativa L) grains were determined during 18 days of germination in a dark room. The effect of phytic acid on α-amylase activity was studied in vitro. Rice grains immersed in sterilised deionised water at 14^°C germinated on the fifth day. Phytase activity, detected in the ripening rice grains, increased linearly until the eighth day and reached a maximum on the tenth day. There was a marked decrease in phytate and an increase in inorganic phosphorus accompanying germination. There was a good inverse correlation between the levels of both phytase activity and inorganic phosphorus, and phytate breakdown. α-Amylase activity was detected on the fourth day and increased markedly from the 12th to the 16th day of germination. ATP level increased from the second to the fourth day and slightly decreased from the fourth to the eighth day; it increased rapidly again from the eighth to the 18th day of germination. α-Amylase activity was influenced by both pH and phytic acid concentration in the assay system. At 75 mM phytic acid, α-amylase activity was lowered by 23%, 93% and 52% at pH 4–0, 5–0 and 6–0 respectively. When the enzyme, phytate and Ca²⁺ were incubated together at pH 5–0, the inhibition of α-amylase by phytic acid was markedly decreased by addition of Ca²⁺. The chemical affinity of Ca²⁺ for phytic acid was higher in the reaction at pH 5–0 than in those at pH 4–0 and pH 6–0, and over 98% of Ca²⁺ in the reaction system was precipitated as Ca-phytate.     

Determination of interfacial mechanical properties of ceramic composites by the compression of micro-pillar test specimens

A novel method to determine the fiber-matrix interfacial properties of ceramic matrix composites is proposed and evaluated; where micro-pillar samples containing inclined fiber/matrix interfaces were prepared from a SiC fiber-reinforced SiC matrix composites and then compression-tested using the nano-indentation technique. This new test method employs a simple geometry and mitigates the uncertainties associated with complex stress state in the conventional single-filament push-out method or tensile unloading–reloading hysteresis loop analysis method for the determination of interfacial properties. Based on the test results using samples with different interface orientations, the interfacial debond shear strength and the internal friction coefficient are explicitly determined and compared with values obtained by other test methods. SEM observation showed that micro compression caused an adhesive type of debonding between the fiber and the pyrolytic carbon interface. The results suggest that the debonding/failure behavior of the micro-pillars followed the Coulomb fracture criterion. The determined interfacial debond shear strength is ~100 MPa, which appears to be smaller than that determined from fiber push-out test for similar composite systems. The difference can be explained by the effect of normal stress (clamping stress) on the apparent interfacial debond shear strength.     

Mixing time and fluid flow phenomena in liquids of varying kinematic viscosities agitated by bottom gas injection

A model experiment was carried out to investigate the mixing condition and related fluid flow phenomena in a slag layer of metal-refining processes agitated by bottom gas injection. Silicone oil was used as a model for the molten slag. Mixing time in a silicone oil bath was measured with a newly developed laser optical sensor. Measured mixing time values increased with an increase in the kinematic viscosity of the silicone oil. In order to explain the relation between mixing time and the kinematic viscosity of silicone oil, the rising velocity of bubbles and the vertical and horizontal velocities of silicone oil flow were measured with an electroresistivity probe and a laser Doppler velocimeter, respectively. The increase in the mixing time with the kinematic viscosity of silicone oil was caused mainly by the suppression of upward motion of bubbles and silicone oil in the bubbling jet region. An empirical correlation for the mixing time was derived as a function of the kinematic viscosity of silicone oil, in addition to conventionally used parameters such as the gas flow rate, bath diameter, and bath depth.     

Corrosion of inconel 617 in HTGR grade helium

Corrosion of the primary circuit materials is one of the serious problems in High Temperature Gas-cooled Reactors (HTGR). In the present work, the effect of gaseous impurities in the helium coolant on the corrosion behavior of Inconel 617 has been studied at 1000 °C and atmospheric pressure for 1000 h. The helium gases used contained several impurities; H₂, H₂O, CH₄, CO, and CO₂. The corrosion behavior of alloying elements (Cr, Mo, Si, C) was strongly affected by the impurity concentration in helium and the extent of corrosion could be explained on the basis of the oxygen and carbon potentials in the gases used. Ryoji Watanabe, formerly Head of Nuclear Materials Division.     

Dimensional Stability and Flame Resistance of Silicate-Acetylated and -Propionylated Wood Composites

Abstract

Silicate-acetylated wood (SAW) and silicate-propionylated wood (SPW) composites were prepared, and the dimensional stability and flame resistance of these composites were evaluated. The silicate gels had insignificant effects on the rate of acetylation or propionylation of wood. In the presence of silicate gels, the SAW and SPW composites showed slightly lower anti-swelling efficiency (ASE) during water or moisture absorption and a lower moisture excluding efficiency (MEE) than the corresponding acetylated wood and propionylated wood, but the SAW and SPW composites still retained fairly good dimensional stability. The oxygen indices (OIs) of the SAW and SPW composites were higher than those of untreated wood specimens and increased with an increase in the weight percent gains (WPG_siS) of silicate gel fixation. The silicate gel fixation endowed the composites with flame resistance.     

Remarkable thermal stability of doubly intramolecularly cross-linked hen lysozyme

In order to examine how a protein can be effectively stabilized,two intramolecular cross-links, Glu35–Trp108 and Lys1–His15,which have few unfavorable interactions in the folded state,were simultaneously introduced into hen lysozyme. Both of theintramolecularly cross-linked lysozymes, 35–108 CL and1–15 CL, containing cross-links Glu35–Trp108 andLys1–His15, respectively, showed increases in thermalstability of 13.9 and 5.2°C, respectively, over that ofwild type, at pH 2.7. On the other hand, a doubly cross-linkedlysozyme showed an increase in thermal stability of 20.8°Cover that of wild type, under identical conditions. Since thesum of the differences in denaturation temperature between wildtype and each of the cross-linked lysozymes was nearly equalto that between wild type and the doubly cross-linked lysozyme,we suggest that the efficient stabilization of the lysozymemolecule was the direct result of the double intramolecularcross-links.     

Opportunities for Expanding Encoded Chemical Diversification and Improving Hit Enrichment in mRNA-Displayed Peptide Libraries

DNA-encoded small-molecule libraries and mRNA displayed peptide libraries both use numerically large pools of oligonucleotide-tagged molecules to identify potential hits for protein targets. They differ dramatically, however, in the ‘drug-likeness’ of the molecules that each can be used to discover. We give here an overview of the two techniques, comparing some advantages and disadvantages of each, and suggest areas where particularly mRNA display can benefit from adopting advances developed with DNA-encoded small molecule libraries. We outline cases where chemical modification of the peptide library has already been used in mRNA display, and survey opportunities to expand this using examples from DNA-encoded small molecule libraries. We also propose potential opportunities for encoding such reactions within the mRNA/cDNA tag of an mRNA-displayed peptide library to allow a more diversity-oriented approach to library modification. Finally, we outline alternate approaches for enriching target-binding hits from a pooled and tagged library, and close by detailing several examples of how an adjusted mRNA-display based approach could be used to discover new ‘drug-like’ modified small peptides.     

Degradation Profiles of Potato Starch Melts Through a Capillary Tube Viscometer

The effects of time‐temperature and strain history on potato starch melts at 150 °C were investigated by use of a capillary tube viscometer. Reciprocating and single extrusions were performed in this study. Shear stress at single extrusion decreased gently as initial heating time increased, while shear stress at reciprocating extrusion decreased rapidly as the number of extrusion strokes increased. A high degree of cold water solubility was obtained by reciprocal extrusion at lower moisture content. From the results of gel filtration it could be concluded that starch molecules were depolymerized by high and reciprocal shear stress. According to these results time‐temperature history was more effective on the depolymerization of starch molecules and degradation of starch granules at higher moisture content, while strain history was more effective at lower moisture content.     

Asymmetric Hydrogenation of Ketones with Polymer‐Bound BINAP/Diamine Ruthenium Catalysts

The BINAP/1,2‐diphenylethylenediamine RuCl₂ complexes bound to a polystyrene resin act as precatalysts for asymmetric hydrogenation of various simple ketones. The enantioselectivity, turnover number, and turnover frequency are comparable to those attained under homogeneous conditions.