Studies on the Dehydrogenative Polymerizations of Monolignol β‐Glycosides. Part 1. Syntheses of Monolignol β‐glycosides, (E)‐Isoconiferin, (E)‐Isosyringin,and (E)‐Triandrin

Abstract

(E)‐4‐O‐Acetyl coniferyl alcohol was synthesized by the reduction of (E)‐4‐O‐acetyl ferulic acid with sodium borohydride and N,N‐dimethylchloromethylenium chloride in 80.2% yield. The glycosylation of (E)‐4‐O‐acetyl coniferyl alcohol with trichloroacetimidoyl 2,3,4,6‐tetra‐O‐pivaloyl‐α‐D‐glucopyranoside in the presence of BF₃-Et₂O in anhydrous CH₂Cl₂, followed by deacylation gave (E)‐isoconiferin in high yield. This synthetic method could be applied to the syntheses of other monolignol β‐glycosides. As a result, (E)‐isoconiferin, (E)‐isosyringin, and (E)‐triandrin were synthesized from vanillin, syringaldehyde, and p‐hydroxybenzaldehyde, respectively, by five reaction steps in high overall yield.     

Growth mechanisms for atypical forms of silicon nanowires

An investigation was carried out into the growth mechanisms for atypical forms of silicon nanowires (Si-NWs) synthesized using a vapor-liquid-solid growth process assisted by hydrogen radicals. Sn or Au nanoparticles, which act as catalysts during Si-NW growth, were produced by hydrogen radical treatment of Sn or Au thin films covering a silicon substrate. The Si-NWs were synthesized from silane gas excited by hydrogen radicals in the presence of these nanoparticle catalysts. In addition to normal Si-NW structures, atypical forms such as tapered, branched, bent, corrugated and block types, were synthesized. The growth of tapered, branched and bent-type Si-NWs was caused by contraction of the catalytic nanoparticles, adhesion of nanoparticles to the side wall of growing Si-NWs, and non-uniform supersaturation of the nanoparticles with Si, respectively. Growth of corrugated- and block-type Si-NWs was induced by an excess supply of Si atoms to the growing Si-NWs.     

Tetragonal—Monoclinic Phase Transition Enthalpy and Temperature of ZrO2-CeO2 Solid Solutions

DSC (differential scanning calorimeter) measurements were performed to investigate the tetragonal-monoclinic ( t-m ) transition enthalpy of the compositionally homogeneous ZrO₂- X mol% CeO₂ solid solution of X = 0, 4, 8, and 12. The transition enthalpy decreases linearly with an increase of CeO₂ content. The m → t transition enthalpy on heating agreed well with the inverse t → m one obtained during cooling. With increasing X , the DSC peak broadens and the transition temperature distribution of each sample increases, while the thermal hysteresis is almost independent of X .     

Determination of unsaturation in ethylene-propylene terpolymers and butyl rubber by time-averaged 1H n.m.r. measurements

The time-averaged ¹H n.m.r. spectra of ethylene-propylene-dicyclopentadiene, ethylene-propylene-ethylidene norbornene and isobutylene-isoprene copolymers were measured. Assignments of the olefinic resonances were carried out by comparing the spectra with those of each homopolymer and strarting monomers. The concentration of the olefinic unit in copolymer was determined by measuring the intensity ratio between the olefinic proton signal and the signal of trichloroethylene which was added as an internal standard of intensity measurements. The concentrations of unsaturation in copolymers determined by using the iodine-mercuric acetate method were proportional to those determined by the n.m.r. method. The accuracy and precision of the n.m.r. measurements were shown to be better than 10% for a mixture of polyisobutylene and polyisoprene containing 1.24 mol % of unsaturation as a model compound of isobutylene-isoprene copolymer.     

Total Synthesis and Structural Revision of Kasumigamide,and Identification of a New Analogue

Kasumigamide is an antialgal hybrid peptide–polyketide isolated from the freshwater cyanobacterium Microcystis aeruginosa (NIES-87). The biosynthetic gene cluster was identified from not only the cyanobacterium but also Candidatus “Entotheonella”, associated with the Japanese marine sponge Discodermia calyx. Therefore, kasumigamide is considered to play a key role in microbial ecology, regardless of the terrestrial and marine habitats. We now report synthetic studies on this intriguing natural product that have led to a structural revision and the first total synthesis. During this study, a new analogue, deoxykasumigamide, was also isolated and structurally validated. This study confirmed the presence of the unusual pathway in the biosynthesis of a hybrid peptide–polyketide natural product.     

Long-term thermal stability of carbon fibre-reinforced addition-type polyimide composite in terms of compressive strength

A previously developed carbon fibre-reinforced addition-type polyimide composite material was exposed to temperatures of 240, 270 and 300 °C in air for 3000 h to study its long-term stability in terms of its compressive strength. The in-plane shear modulus, compressive failure mode and transverse crack density were also evaluated to determine whether a degradation process induces a decrease in the compressive strength of a high-temperature polymer matrix composite having a laminated configuration of [90/0]_4s. The carbon fibre-reinforced polyimide composite exhibited excellent thermal stability in terms of its compressive strength after being subjected to ageing at 240 °C for 3000 h and at 270 °C for 2000 h, with degradation becoming significant at 300 °C. The compressive strength decreased only when the surface degradation caused the 90° plies sandwiching the 0° plies to degrade severely.     

Tools for constructing pseudo-3D space on the WWW using images

Recently, due to advancements in virtual reality and computer graphics technologies, a virtual space that looks as real as a real space has been constructed. Accordingly, there are many studies that employ virtual spaces to support human communication and remote working. Until now, the virtual space employed by these studies has been composed of geometric models. Since the real space is very large and there are a lot of objects in the real world, the cost of modeling the real space is very high. In our previous paper,¹⁰⁾ we proposed a method for building a virtual space using image data, named theimage based non-rendering (IBNR), in order to cut down the cost. In this paper, we explain the design and implementation of the tools which we implemented to construct virtual spaces based on IBNR. With these tools, it is easy to construct and renew a large-scaled virtual space based on the real space. Takefumi Ogawa: He received his B.E. and M.E. degrees in Information Systems Engineering from Osaka University, Osaka, Japan, in 1997 and 1999, respectively. Currently, he is a Research Associate of the Infomedia Education Division, Cybermedia Center, Osaka University. He is a member of IEEE, IEICE, IPSJ, and VRSJ. His research interests include virtual reality systems and augmented reality systems. Masahiko Tsukamoto, Ph.D.: He received his B.E., M.E., and Dr.E. degrees from Kyoto University, Kyoto, Japan, in 1987, 1989, and 1994, respectively. From 1989 to February 1995, he was a research engineer of Sharp Corporation. Since March 1995, he has been an Assistant Professor in the Department of Information Systems Engineering of Osaka University and since October 1996, he has been an Associate Professor at the same department. He is a member of seven learned societies, including ACM and IEEE. His current research interests include database systems, knowledge-base systems, and distributed computing systems.     

Elevated Cytokine Levels in Aqueous Humor Are Associated with Peripheral Anterior Synechiae after Penetrating Keratoplasty

Peripheral anterior synechiae (PAS) after corneal transplantation leads to refractory glaucoma and permanent loss of vision. However, the exact mechanism remains elusive. This study aimed to evaluate the association between cytokine levels in the aqueous humor (AqH) and the progression of PAS after penetrating keratoplasty (PKP). We measured 20 cytokine levels in AqH and assessed the correlation with PAS progression after PKP in 85 consecutive patients who underwent PKP. We also evaluated age-dependent alterations in PAS and cytokine levels in DBA2J mice. PAS developed in 38 (44.7%) of 85 eyes after PKP. The incidence of intraocular pressure increase after PKP was significantly greater in eyes with PAS (26.3%) than in those without PAS (2%, p = 0.0009). The PAS area at 12 months after PKP was significantly positively correlated with the preoperative levels of interleukin (IL)-6, interferon (IFN)-γ and monocyte chemotactic protein (MCP)-1 (p ≤ 0.049). In the DBA2J mice, an experimental glaucoma model that developed PAS at 50 weeks, the AqH levels of IL-2, IL-6, IL-10, IFN-γ, tumor necrosis factor-α, MCP-1 and granulocyte-macrophage colony-stimulating factor (GM-CSF) significantly increased at 50 weeks compared to 8 weeks (p ≤ 0.021). In conclusion, inflammatory alterations in the AqH microenvironment, such as high preoperative specific cytokine levels, can lead to PAS formation and glaucoma.     

Enhancement of the adhesive force of metal films on PTFE surface achieved by fast-atom-beam surface modification

We tried the method to increase the peel strength between thin film metals and various substrate materials using saddle field fast atom beam (FAB) sources. It is notable that the peel strength was increased more than several times for all substrates than those who were not modified by surface activation using FAB irradiation. Highest peel strength was observed at the coupling of Si and metals in both case of Ar irradiation and SF₆ reactive etching by FAB. This surface activation technique was applied to the fabrication of microelectrodes for the detection of mouse nerve signals. The process is expected as one of the available techniques for pre-treatment of the film deposition for several electrical devices.     

An implicit curve-fitting method for fast calculation of thermal properties of pure and mixed refrigerants

Calculations of refrigerant thermal properties are desired to be very fast and stable in cases of simulation of refrigeration system, etc. The traditional method based on equation of state cannot meet such requirement because of unavoidable iterations in calculation. In this paper, a new calculation method for refrigerant thermal properties is presented. Low order implicit polynomial equations are got by using curve-fitting method at first, and then explicit formulae for calculating refrigerant thermal properties quickly are obtained by getting the analytical solution of these implicit equations. Explicit fast calculation formulae for thermal properties of R22 and R407C, covering the saturated temperature of −6080 °C and superheat of 0–65 °C, are presented as examples. The calculation speeds of the formulae of R22 are about 140 times faster than those of REFPROP 6.01 while the formulae of R407C are about 1000 times faster. The total mean relative deviations of the fast calculation formulae for R22 and R407C are less than 0.02%.