Biotransformation of l‐menthol by twelve isolates of soil‐borne plant pathogenic fungi (Rhizoctonia solani) and classification of fungi

The microbial transformation of l‐menthol ( 1 ) was investigated by using 12 isolates of soil‐borne plant pathogenic fungi, Rhizoctonia solani (AG‐1‐IA Rs24, Joichi‐2, RRG97‐1; AG‐1‐IB TR22, R147, 110.4; AG‐1‐IC F‐1, F‐4, P‐1; AG‐1‐ID RCP‐1, RCP‐3, and RCP‐7) as a biocatalyst. Rhizoctonia solani F‐1, F‐4 and P‐1 showed 89.7–99.9% yields of converted product from 1 , RCP‐1, RCP‐3, and RCP‐7 26.0–26.9% and the other isolates 0.1–12.0%. In the cases of F‐1, F‐4 and P‐1, substrate 1 was converted to (?)‐(1S,3R,4S,6S)‐6‐hydroxymenthol ( 2 ), (?)‐(1S,3R,4S)‐1‐hydroxymenthol ( 3 ) and (+)‐(1S,3R,4R,6S)‐6,8‐dihydroxymenthol ( 4 ), which was a new compound. Substrate 1 was converted to 2 and/or 3 by RRG97‐1, 110.4, RCP‐1, RCP‐3 and RCP‐7. The structures of the metabolic products were elucidated on the basis of their spectral data. In addition, metabolic pathways of the biotransformation of 1 by Rhizoctonia solani are discussed. Finally, from the main component analysis and the differences in the yields of converted product from 1 , the 12 isolates of Rhizoctonia solani were divided into three groups based on an analysis of the metabolites. Copyright © 2003 Society of Chemical Industry     

Emission of core-excited autoionizing sodium atoms from NaCl induced by electron bombardment

In the time-of-flight spectrum of positive ions produced by electron bombardment of NaCl surface a delayed signal of Na⁺ is detected. This observation is attributed to production of core-excited autoionizing metastable Na^** atoms which have their characteristic lifetimes in the 100 ns range. Moreover, it is noticed that the populations of the various metastable Na^** states depend on the NaCl layer thickness. The lifetimes of some quartet metastable Na^** states have been determined as well.     

Electrical passivation of the silicon surface by organic monolayers of 1-octadecene

The electrical properties of structures consisting of a monolayer of 1-octadecene deposited on the Si surface are investigated depending on the method of passivation of the surface prior to the deposition of the film (hydrogen and ion passivation) and the intensity of illumination which activates the addition reaction of molecules of 1-octadecene to the Si atoms. The monolayer of 1-octadecene on the Si surface is stable and provides the chemical passivation of the surface. Two types of traps are found, namely, traps for holes and electrons, whose density can be varied during deposition of the monolayer by the choice of intensity of illumination and by the method of passivation of the surface. In the case of a low level of illumination and/or the use of the iodine passivation of the surface, the electron traps prevail, and, in the case of high intensity of illumination and/or hydrogen passivation of the surface, the hole traps prevail. It is shown that the use of these films provides conductivity in thin near-surface layers of Si due to providing the mode of flat bands or accumulation of carriers near the surface.     

Fabrication and characteristics of novel microelectronic structures fabricated by plasma-based techniques

A number of novel microelectronic structures have recently been produced using plasma-based techniques such as plasma immersion ion implantation (PIII) and this paper describes the recent progress made in this area in our laboratory. Conventional silicon-on-insulator (SOI) substrates utilizing a buried silicon dioxide layer suffer from self-heating effects as device dimensions shrink to the deep-submicrometer regime. Novel SOI structures using dielectric materials with higher thermal conductance such as aluminum nitride and diamond-like carbon have been produced. In the area of high-k (dielectric constant) thin films, plasma nitridation conducted on materials such as zirconium dioxide improves the recrystallization and interfacial properties. In the conventional Smart-Cut™ or ion-cut technique, high-energy hydrogen implantation is performed to effect layer transfer. Low-energy (several hundred eVs) plasma hydrogenation has recently been conducted in conjunction with damage engineering to produce wafer splitting for layer transfer. This new process allows more flexible control of the depth of hydrogen accumulation and the location of layer cleavage.     

基于RS-485总线的调度模拟盘控制系统

针对以往调度模拟盘控制系统采用非智能化功能单元、并行传输方式所带来的种种弊端,例如:易受到干扰、接线复杂、不能实现显示单元自检及动态潮流方向显示等,本文提出一种基于RS-485总线的解决方案。     

Ab-initio study of electronic and elastic properties of Mg(BH4)(NH2) complex hydride

Structural and electronic properties of complex hydride Mg(BH₄)(NH₂), applicable in hydrogen storage, were studied in framework of pseudopotential-density functional theory. This compound shows an indirect band gap of 4.95 eV which is categorized in insulator materials. The calculated total and partial density of states of this compound show that the hydrogen bonding in BH₄ anion is mainly covalent and the hydrogen-hydrogen repulsion is more in anion BH₄ than in anion NH₂. The calculated bulk modulus from Birch-Murnaghan equation of state is in close agreement with that obtained from the elastic constants. The obtained bulk modulus (19.27 GPa) shows this compound is more ductile than binary and ternary hydrides and it does not have a brittle structure. Therefore, it is a good candidate for hydrogenation and dehydrogenation cycles. The stability of the structure in ambient pressure is also declared by calculating the elastic coefficients. However, the existence of elastic anisotropy in the compound demonstrates the less compressibility of it along the c axis than a and b axes. The small amount of Poisson ratio indicates that it is more stable against shear compared to common borohydrides. This point is important for hydride stability in hydrogenation and dehydrogenation cycles.     

现代营销理论演绎

文章对现代营销理论中的4Ps,4Cs,4Rs的理论内涵与应用进行了阐述与分析,并对这三种理论的内在联系进行了研究与探讨,能启迪营销人员在营销的实践工作中把营销理论与实际工作有机地结合起来.     

Dielectric and microwave absorbing properties of low power plasma sprayed Al2O3/Nb composite coatings

Al₂O₃/Nb composite coatings were sprayed on graphite substrates by low power atmospheric plasma spraying (LPAPS) with an internally fed powder torch. The composite particles were agglomerated with different mass fractions by spray-drying technology. The microstructure and dielectric properties of coatings were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles in the composite coatings. Both the real (?′) and imaginary (?″) parts of the complex permittivity increase with increasing Nb content over the frequency range of 8.2-12.4 GHz, which is ascribed to space charge polarization and conductance loss, respectively. By calculating the microwave-absorption as a single-layer absorber, reflection loss values exceeding −10 dB can be obtained in the frequency range of 10.0-11.8 GHz with 10 wt% Nb content coating when the coating thickness is 1.5 mm.     

The gas flux distribution in the XHV chamber of the vacuum primary standard developed by PTB

The ultimate pressure in the XHV calibration chamber of the PTB primary standard CE3, whose operation is based on the continuous expansion of gas, has been reduced by the use of a relatively large orifice area. Thus, the gas density and flux distributions cannot be taken as uniform in the calibration chamber. To eliminate this drawback we examined the gas flux distribution by Direct Simulation using the Monte Carlo method. This paper describes the gas flux distribution over the chamber walls, which was simulated, recorded and related to the idealized conditions. This allows determining the gauge position correction factor K_gi for each of the gauge ports. Using these factors, it is possible to eliminate the systematic deviation of the gas flow parameters from those under the idealized Maxwellian conditions and to improve the uncertainty budget.     

TE013 Mode High Temperature Superconductor Millimeter Resonator

This paper describes a TE₀₁₃ mode dielectric resonator at 36.098 GHz. The dielectric resonator was formed by sandwiching a cylindrical piece of polished dielectric (sapphire) rod between two GdBa₂Cu₃O_7–x (GBCO) High Temperature Superconductor (HTS) thin films. The resonator was tested as a two-port device at a temperature of 77 K. A 62700 unload quality factor Q ₀ was obtained. The surface resistance (Rs) of the HTS film had been determined as 9.4 m at 77 K and 36 GHz.