Isolation and Characterization of Two Types of Xyloglucanases from a Phytopathogenic Fungus,Verticillium dahliae

Xyloglucan is a major hemicellulosic component in plant cell walls. Phytopathogenic fungi secrete cell wall-degrading enzymes on their infection to hosts, while the nature of the cell wall-lytic enzymes of such fungi are yet to be fully understood. Verticillium dahliae is a soil-borne fungus that causes vascular wilt diseases in a variety of commercially important crops worldwide. We purified two types of xyloglucanases, XEG12A and XEG74B, from the culture of naturally isolated Verticillium dahliae strain 2148. XEG12A showed a molecular size of 23 kDa with its maximal activity at pH 7.5. XEG12A specifically hydrolyzed xyloglucan with no activity on other β-glucans. XEG74B had a molecular size of 110 kDa with its optimum pH at 6.0. XEG74B primarily hydrolyzed xyloglucan, with a slight activity on β-1,3-1,4-glucan. Analysis of hydrolytic products of xyloglucanooligasaccharide (XXXGXXXG) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) revealed that the both enzymes cleaved β-1,4-glucosidic linkage at the position of unbranched chain, while XEG74B showed a little fluctuation with the cleavage site. Both enzymes did not hydrolyzed xyloglucanoheptasaccharide (XXXG) at all. N-Terminal and internal amino acid sequencing of the enzymes revealed that XEG12A and XEG74B belonged to Glycoside Hydrolase (GH) Families 12 and 74, respectively. Based on these results we concluded that V. dahliae XEG12A and XEG74B were xyloglucan-specific endo-β-1,4-glucanases (EC 3.2.1.151).     

13 years’ operational experience of SPring-8 vacuum system

The first electron beam was stored in SPring-8 storage ring in March 1997. An overview of the 13 years’ operational experience concerning the vacuum system of the SPring-8 storage ring is presented. The evolution of the vacuum system and their performance are summarized. Moreover, the main vacuum failures and their impact on accelerator operation are described in detail. We analyze the relationship between the difference types of vacuum failure and downtime of user experiment.     

Fabrication of BSCF-based mixed oxide ionic-electronic conducting multi-layered membrane by sequential electrophoretic deposition process

The Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF)-based multi-layered oxygen separation membrane was fabricated by the sequential electrophoretic deposition (EPD) process. A thin porous/dense bi-layer of BSCF was formed on a thick porous support of BSCF. The porous support prepared by a sacrificial template method using BSCF powder mixed with wheat starch (30 wt%) as a pore-forming agent, followed by uniaxial pressing and low-temperature sintering, was directly used as an EPD electrode. A thin BSCF layer was first formed on the porous support, and then a thin BSCF + PMMA (polymethyl methacrylate) layer was sequentially formed on the thin BSCF layer using a bimodal suspension of BSCF and PMMA. A 30-μm thin porous/dense bi-layer of BSCF of which the total thickness was obtained by optimizing the processes of EPD and subsequent co-sintering. The oxygen separation performance of 3.7 ml (STP) min^?1 cm^?2 at 860 °C was achieved for the BSCF-based multi-layered oxygen separation membrane.     

微波场中加热高钛高炉渣的数值模拟

利用微波加热技术在高钛高炉渣内引发裂纹的实验过程中发现炉渣局部区域发生热失控现象.为探寻高钛高炉渣在微波场中产生热失控的原因,使用 FEMAP 和 wave-jω 软件计算了在多模式微波炉中高钛高炉渣及其周围空间内微波场和热三维分布情况,并对比研究了钙钛矿相和普通高炉渣吸收微波的能力.通过计算结果可知几乎所有的微波能都集中在被加热的高钛高炉渣试样中,即微波具有加热高钛渣自身而非周围环境的特点.另外,高钛高炉渣试样中微波场分布不均匀,且分散在炉渣中的钙钛矿相比其他矿物相更易被微波加热.以上 2 因素作用下微波加热高钛高炉渣时局部区域发生热失控现象.     

Effects of phosphorus content on generation and growth of cracks in nickel–phosphorus platings owing to thermal cycling

We observed crack generation and structural changes in electroless nickel–phosphorus (Ni–P) plating layers formed on copper-metalized silicon nitride substrates both during thermal cycling from ? 40 to 250 °C and during storage (not cycling) at 250 °C in order to investigate the effect of the phosphorus contents on crack generation and growth in the Ni–P platings. The used platings contained phosphorus at three different contents: 2.1 wt% [Ni–P(low)], 6.5 wt% [Ni–P(med)], and 10.9 wt% [Ni–P(high)]. The generation time and the amount of cracks were strongly dependent on their phosphorus contents. More cracks appeared after thermal cycling than after storage at 250 °C. In Ni–P(low), cracks were generated after 200 thermal cycles, whereas no cracks were observed even after 250 h of storage at 250 °C. In Ni–P(med) and Ni–P(high), both during thermal cycling and storage at 250 °C, cracks formed during or after crystallization of the amorphous layers. These results suggest that the primary factors affecting the generation of cracks in electroless Ni–P platings are crystallization of the Ni–P platings and repeated changes in thermal stress.     

A Water‐Soluble Mechanochromic Luminescent Pyrene Derivative Exhibiting Recovery of the Initial Photoluminescence Color in a High‐Humidity Environment

Switching of the luminescence properties of molecular materials in response to mechanical stimulation is of fundamental interest and also has a range of potential applications. Herein, a water‐soluble mechanochromic luminescent pyrene derivative having two hydrophilic dendrons is reported. This pyrene derivative is the first example of a mechanochromic luminescent organic compound that responds to relative humidity. Mechanical stimulation (grinding) of this pyrene derivative in the solid state results in a change of the photoluminescence from yellow to green. Subsequent exposure to water vapor induces recovery of the initial yellow photoluminescence. The color change is reversible through at least ten cycles. It is also demonstrated that this compound can be applied as a mechano‐sensing material in frictional wear testing for grease, owing to its immiscibility in non‐polar solvents and its non‐crystalline behavior. Transmission electron microscope and atomic force microscope observations of samples prepared from dilute aqueous solutions of the pyrene derivative on suitable substrates, together with dynamic light scattering measurements for the compound in aqueous solution, indicate that this amphiphilic dumbbell‐shaped molecule forms micelles in water.