Holographic recording in a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various polarizations

Surface relief (SR) gratings with a molecularly oriented structure and pure polarization hologram were fabricated on a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various two-beam polarization modes. For intensity holography, the polarization information from the two beams simultaneously provided the molecular motion and molecular reorientation; the SR height reached up to 186 nm and the concave area revealed a molecular reorientation when the exposing beams were linearly polarized. In contrast, SR formation was negligible for polarization holography when molecular reorientation due to the polarization modulation was observed. The resulting polarization gratings changed the polarization properties of the diffraction beams, and their diffraction efficiency was reached 24%, which agreed with theoretical expectations.     

Properties of silicious film on polycarbonate substrate prepared by vacuum ultraviolet irradiation: Effect of intermediate silane layer

We studied the effect of vacuum ultraviolet irradiation (VUV) on siliceous coatings of polycarbonate substrates derived by the sol-gel method, with the aim of improving the abrasion resistance of the substrate surface. The experimental conditions to insert an intermediate silane layer between siliceous film and polycarbonate substrate were examined in order to enhance the abrasion resistance and adhesion strength, using four kinds of silane coupling reagents, i.e., 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilne, phenyltriethoxysilne and ethyltriethoxysilane. After the formation of intermediate silane layer on the PC substrate, siliceous film was further prepared on it by VUV irradiation of the spin-coated sol solution containing methyltriethoxysilane and colloidal silica. Among the silanes examined in this research, 3-aminopropyltrimethoxysilne notably played a role as an appropriate intermediate layer for the enhanced abrasion resistance of siliceous-coated polycarbonate substrate. The average transmittance was kept as high as 70% even after abraded 140 turns.     

Evolved Diversification of a Modular Natural Product Pathway: Apratoxins F and G,Two Cytotoxic Cyclic Depsipeptides from a Palmyra Collection of Lyngbya bouillonii

A collection of Lyngbya bouillonii from Palmyra Atoll in the Central Pacific, a site several thousand kilometers distant from all previous collections of this chemically prolific species of cyanobacterium, was found to contain two new cancer cell cytotoxins of the apratoxin family. The structures of the new compounds, apratoxins F and G, were determined by 1D and 2D NMR techniques in combination with mass spectrometric methods. Stereochemistry was explored by using chromatographic analyses of the hydrolytically released fragments in combination with NMR and optical rotation comparisons with known members of the apratoxin family. Apratoxins F and G add fresh insights into the SAR of this family because they incorporate an N‐methyl alanine residue at a position where all prior apratoxins have possessed a proline unit, yet they retain high potency as cytotoxins to H‐460 cancer cells with IC₅₀ values of 2 and 14 nM , respectively. Additional assays using zone inhibition of cancer cells and clonogenic cells give a comparison of the activities of apratoxin F to apratoxin A. Additionally, the clonogenic studies in combination with maximum tolerated dose (MTD) studies provided insights as to dosing schedules that should be used for in vivo studies, and preliminary in vivo evaluation validated the predicted in vivo efficacy for apratoxin A. These new apratoxins are illustrative of a mechanism (the modification of an NRPS adenylation domain specificity pocket) for evolving a biosynthetic pathway so as to diversify the suite of expressed secondary metabolites.     

Thermal characteristics of nongraphitizable carbon negative electrodes with electrolyte in Li-ion batteries

Two kinds of nongraphitizable carbon were applied as active materials of negative electrodes in Li-ion batteries. The thermal properties of cycled electrodes mixed with or without commercial 1 M LiPF₆/EC–DMC electrolyte were investigated by TG–DSC from room temperature to 400 °C at a heating rate of 5 °C/min. Both kinds of lithiated electrodes showed exothermic peaks at about 310 °C due to decomposition of SEI by lithiated carbon powder. For the mixture of delithiated electrodes and electrolytes, the heat generation was attributed mainly to thermal decomposition of the electrolyte at about 280 °C. But for the mixture of lithiated electrodes and electrolytes, thermal risk mainly came from the reaction between original/secondary SEI and intercalated Li ions, which caused drastic heat generation at about 285 °C. Moreover, the thermal behavior of the mixture of cycled electrodes and electrolytes was directly related to the ratio between electrodes and coexisting electrolytes. When the ratio between electrodes and electrolytes was suitable, an endothermic reaction between SEI and electrolytes became dominant and depressed other exothermic heat, which reduced the thermal risk of the mixture of electrodes and electrolytes at elevated temperature.     

Global Loss of Core 1-Derived O-Glycans in Mice Leads to High Mortality Due to Acute Kidney Failure and Gastric Ulcers

The core 1 structure is the major constituent of mucin-type O-glycans, which are added via glycosylation—a posttranslational modification present on membrane-bound and secretory proteins. Core 1 β1,3-galactosyltransferase (C1galt1), an enzyme that synthesizes the core 1 structure, requires Cosmc, a C1galt1-specific molecular chaperone, for its enzymatic activity. Since Cosmc-knockout mice exhibit embryonic lethality, the biological role of core 1-derived O-glycans in the adult stage is not fully understood. We generated ubiquitous and inducible CAGCre-ER^TM/Cosmc-knockout (iCAG-Cos) mice to investigate the physiological function of core 1-derived O-glycans. The iCAG-Cos mice exhibited a global loss of core 1-derived O-glycans, high mortality, and showed a drastic reduction in weights of the thymus, adipose tissue, and pancreas 10 days after Cosmc deletion. They also exhibited leukocytopenia, thrombocytopenia, severe acute pancreatitis, and atrophy of white and brown adipose tissue, as well as spontaneous gastric ulcers and severe renal dysfunction, which were considered the causes underlying the high mortality of the iCAG-Cos mice. Serological analysis indicated the iCAG-Cos mice have lower blood glucose and total blood protein levels and higher triglyceride, high-density lipoprotein, and total cholesterol levels than the controls. These data demonstrate the importance of core 1-derived O-glycans for homeostatic maintenance in adult mice.     

A new class of transparent polymeric materials. I. Production and properties of an alternating copolymer of N-methylmaleimide and isobutene

An alternating copolymer of N-methylmaleimide and isobutene was produced by a radical precipitation polymerization method. The copolymer thus produced is a new class of transparent polymeric material that shows a unique balance of optical, thermal, and mechanical properties. The visible light transmittance was more than 90% and the stress optical coefficient was smaller than that of polycarbonate, leading to moldings with lower birefringence. The heat deflection temperature of the copolymer was as high as 157°C, and the thermal expansion coefficient was about 30% smaller than those of poly(methyl methacrylate) and polycarbonate. The copolymer showed excellent mechanical properties, specifically, the flexural modulus was the highest among the typical amorphous polymers. © 1996 John Wiley & Sons, Inc.     

Rendering of forest scenery using 3D textures

Visual simulation of forest scenery is a challenging problem which includes the following tough sub-problems: generation of vegetation, representation of trees, simulation of colour change of leaves, and rendering of numerous trees. Among those sub-problems, this paper treats mainly the last one. A conventional polygon-based rendering algorithm often produces troublesome aliasing effects when it is applied to the objects having complex fine surfaces, such as forest scenery. In this paper, we show that an extended volume rendering technique applied to 3D textures, i.e. volume data in this paper, of trees is effective in the concerned problem. Kajiya left, as further work, the problem of rendering forest scenery by applying his 3D texture called texel. Our rendering method consists of the following three steps: we first generate 3D textures of trees from their polygon-based geometric models, we next arrange the 3D textures, allowing their possible mutual intersections, on the surface of a given polygon-based terrain model according to a simulated vegetation, and we finally produce an image of forest scenery by applying the ray-tracing algorithm including our slightly extended volume rendering technique. © 1997 John Wiley & Sons, Ltd.