Improvement of a Measurement System for Surface Loss Rate of Ozone

Ozone molecules present in high-purity oxygen as a feed gas interact with surfaces and oxygen molecules in an enclosed container. Therefore, some of the ozone molecules are destroyed and the density of ozone decreases with time. An experimental system has been constructed to monitor the temporal decrease in ozone density in a container based on the HgI 254 nm photoabsorption method. Our investigation is focused on the dependence of the effective lifetime of ozone on the wall material at various gas pressures. During the experiments, distortion of the measured decay curves often caused by instabilities in the mercury lamp intensity. We thus attempted to build a simple setup that eliminates the effect of long-term intensity drift. This setup is based on light source intensity monitoring by a separate photodetector and data correction software. This article describes the setup of the experimental apparatus, the results including some preliminary experiments and the temporal variation of the surface loss rate of ozone by repeated measurement along with inspections of the wall surface by Auger electron spectroscopy.     

Euphorbia tirucalli β-Amyrin Synthase: Critical Roles of Steric Sizes at Val483 and Met729 and the CH–π Interaction between Val483 and Trp534 for Catalytic Action

The functions of Val483, Trp534, and Met729 in Euphorbia tirucalli β-amyrin synthase were revealed by comparing the enzyme activities of site-directed mutants against that of the wild type. The Gly and Ala variants with a smaller bulk size at position 483 predominantly afforded monocyclic camelliol C, which suggested that the orientation of the (3S)-2,3-oxidosqualene substrate was not appropriately arranged in the reaction cavity as a result of the decreased bulk size, leading to failure of its normal folding into the chair–chair–chair–boat–boat conformation. The Ile variant, with a somewhat larger bulk, afforded β-amyrin as the dominant product. Intriguingly, various variants of Trp534 exhibited significantly decreased enzymatic activities and provided no aberrantly cyclized products, although the aromatic Phe and Tyr residues were incorporated and the steric sizes of the aliphatic residues were altered. Therefore, the Trp534 residue does not stabilize the transient cation through a cation–π interaction. Furthermore, the Trp residue, with the largest steric bulk among all natural amino acids, is essential for high enzymatic activity. Robust CH–π complexation between the Val483 and Trp534 residues is proposed herein. Altering the steric bulk at the Met729 position afforded the pentacyclic skeletons. Thus, Met729 is positioned at the E-ring formation site. More detailed insights into the functions of the Val483, Trp534, and Met729 residues are provided by homology modeling.     

Evaluation of the bond properties between concrete and reinforcement as a function of the degree of reinforcement corrosion

In order to investigate the effect of reinforcement corrosion on the bond properties between concrete and reinforcement, the pullout tests were conducted using reinforcements embedded in concrete specimens, which were corroded by an accelerated electric corrosion method. A finite element method (FEM) analysis was also carried out on the basis of the results of the pullout tests. The maximum bond strength (τ_max) and the bond rigidity (D_s) of specimens decreased in proportion to the increase of corrosion percentage (Δ_w), respectively. Also, the curves of bond stress-free end slip could be analyzed by the FEM, if the τ_max and D_s were determined as a function of corrosion percentage. The equations for calculating the maximum bond strength and the bond rigidity necessary for an FEM analysis of RC members with corroded reinforcements were obtained by the experiments and the FEM analysis of the pullout tests.     

Crystal transformation from the α- to the β-form upon tensile drawing of poly(l-lactic acid)

A film of poly(l-lactic acid) (PLLA) consisting of highly oriented α crystals was uniaxially drawn by tensile force. The effects of the draw ratio (DR), draw temperature (T_d), and draw stress on the crystal/crystal transformation from the α- to the β-form crystals were studied. At the initial stage of drawing, the highly oriented α crystals of the starting film transformed into a broader orientation distribution, and significant crystal disorder was introduced. Upon further drawing, the α crystals steadily transformed into β crystals with increasing the DR. For the drawing at a constant T_d, the crystal transformation proceeded more efficiently at a higher draw rate and, hence, at a higher draw stress. Furthermore, for the drawing at a constant draw rate, the transformation proceeded with DR most efficiently for the tensile draw at a T_d around 140 °C, although the draw stress increased with decreasing the T_d. The present result combined with the previous finding in the drawing of PLLA by solid-state extrusion [Macromolecules 36 (2003) 3601] suggests that there is a T_d of around 140 °C at which the crystal transformation proceeds most efficiently with DR, suggesting that there are two factors that have opposite effects on the efficiency of the crystal transformation with increasing the T_d. However, as a result of the combined effects of the T_d and DR on the crystal transformation and the ductility increase with the T_d, an oriented film consisting predominantly of β crystals was obtained by tensile drawing at a T_d in the range of 140-170 °C to the highest DR achieved at each T_d.     

Investigation of Ozone Loss Rate Influenced by the Surface Material of a Discharge Chamber

Decay characteristics of ozone concentration in oxygen in a chamber with three types of wall material (stainless steel, copper, and aluminum) are measured using the 254 nm photoabsorption method. Effective lifetimes of ozone are estimated from decay curves of ozone concentration. These values depend on the wall material: They are largest for stainless steel and smallest for aluminum. The relationship between effective lifetime and gas pressure is investigated precisely to determine three values. The equivalent diffusion coefficient of ozone in oxygen and the reflection coefficient of ozone at the wall correspond to the loss rate of ozone at the wall. The collisional loss (quenching) rate coefficient of ozone in oxygen is also determined.     

蒙药材止泻木子生物碱的分离与纯化

以夹竹桃科植物止泻木子的干燥种子为原材料,采用乙醇提取法对其生物碱类物质进行粗提取,通过硅胶柱层析和重结晶技术对生物碱粗提物进行分离和纯化。利用核磁共振波谱和质谱法对其一种生物碱单体进行化学结构和分子量鉴定。实验结果表明,用70%乙醇在60℃条件下静止浸取3次,每次提取6 h,得到止泻木子总生物碱提取物,其得率达到0.244%。经过硅胶柱分离和重结晶纯化,可获得3种生物碱单体。对HPLC检测纯度达到94.89%的2号生物碱单体进行核磁共振波谱和质谱检测,得知该生物碱单体是一个分子量为356.59的锥丝碱（conessine）。该结果有利于了解以止泻木子为主要成分的蒙药药剂作用机理。     

Synthesis of cyclic poly(methyl methacrylate) by the intramolecular cyclization of α-amino, ω-carboxyl heterodifunctional poly(methyl methacrylate)

Summary α-Amino, ω-carboxyl heterodifunctional poly(methyl methacrylate) was prepared by a living anionic polymerization of methyl methacrylate using N,N'-diphenylethylenediamine monolithium amide and succinic anhydride as an initiator and terminator, respectively. Its intramolecular cyclization was carried out to obtain a well-defined cyclic poly(methyl methacrylate). Received: 27 June 2001/Accepted: 16 July 2001     

A 31P-NMR study of peroxo species formed during oxidation of cyclohexene with hydrogen peroxide in tri-n-butylphosphate catalyzed by heteropolyacids

In the oxidation of cyclohexene with H₂O₂in monophasic tri-n-butylphosphate (TBP) solution catalyzed by Keggin-type 12-heteropolyacids, i.e., H₃PMo_12-xW _x O₄₀(x=0–12), several peroxo species were observed by ³¹P-NMR spectroscopy in lower field than the original heteropolyacids. Their composition varied regularly with that of the starting catalyst. The P-containing peroxo species formed was deduced as [PM₄O₈(O₂)₈]^3-(M = Mo, W). The peroxo species formed more easily with a decrease in the W content, x of H₃PMo_12-xW_xO₄₀. It was further indicated from the reactivity with cyclohexene and the comparison with catalytic performance that W-rich peroxo species were catalytically more active than Mo-rich peroxo species for the oxidation of cyclohexene in this reaction system.     

Relationship between Expression of Onco-Related miRNAs and the Endoscopic Appearance of Colorectal Tumors

Accumulating data indicates that certain microRNAs (miRNAs or miRs) are differently expressed in samples of tumors and paired non-tumorous samples taken from the same patients with colorectal tumors. We examined the expression of onco-related miRNAs in 131 sporadic exophytic adenomas or early cancers and in 52 sporadic flat elevated adenomas or early cancers to clarify the relationship between the expression of the miRNAs and the endoscopic morphological appearance of the colorectal tumors. The expression levels of miR-143, -145, and -34a were significantly reduced in most of the exophytic tumors compared with those in the flat elevated ones. In type 2 cancers, the miRNA expression profile was very similar to that of the exophytic tumors. The expression levels of miR-7 and -21 were significantly up-regulated in some flat elevated adenomas compared with those in exophytic adenomas. In contrast, in most of the miR-143 and -145 down-regulated cases of the adenoma-carcinoma sequence and in some of the de novo types of carcinoma, the up-regulation of oncogenic miR-7 and/or -21 contributed to the triggering mechanism leading to the carcinogenetic process. These findings indicated that the expression of onco-related miRNA was associated with the morphological appearance of colorectal tumors.     

Wettability of a microgrid‐structured polymer film with microfabrication utilizing the stick–slip phenomenon

A microgrid structure was formed on the surface of a polyethylene terephthalate (PET) film with an original microfabrication method (termed SS processing) utilizing the stick–slip (SS) phenomenon, and the effect of this surface structure on wettability was evaluated. Microgrid‐structured films could be fabricated by two‐axis SS processing. Moreover, an arbitrary parallelogram microgrid structure could be formed by selecting the direction of the second SS processing with respect to that of the first SS processing. Both water contact angle and water sliding angle of the SS‐processed film were larger than that of the PET film. Hence, the SS‐processed film showed a petal‐like effect. Furthermore, the water sliding angle of the microgrid‐structured film showed anisotropy due to the pinning effect derived from the microgrid structure. As a result, it is revealed that a hydrophobic PET film with a petal‐like effect and anisotropic wettability can be fabricated by SS processing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45140.