Grafting of methyl methacrylate onto collagen initiated by tributylborane

The graft copolymerization of methyl methacrylate onto collagen initiated by tributylborane was investigated in aqueous medium. The total conversion, percentage of grafting and efficiency of grafting increased with increasing collagen content. The optimum conditions on the percentage of grafting and efficiency of grafting were determined by varying initiator concentration, monomer concentration, and polymerization temperature. The grafting onto denaturated collagen was also studied. It has been suggested that the grafting onto collagen proceeds by a radical mechanism via a complex of TBB and hydrated collagen.     

Accurate modeling of dielectric interfaces by the effective permittivities for the fourth-order symplectic finite-difference time-domain method

The fourth-order finite-difference time-domain (FDTD) method using a symplectic integrator propagator can calculate the propagation of the electromagnetic waves with very low dispersion error in the region of a constant or smoothly varying index profile. An additional technique is required for the problem with the discontinuous dielectric interfaces. We derived the third-order effective permittivities at dielectric interfaces for the fourth-order FDTD method in the case of 2D TE polarization. As the required accuracy level is increased, the memory resources used by the fourth-order FDTD method with the effective permittivities are reduced severalfold or more compared with the standard FDTD method. The accurate performance of the proposed method is demonstrated through numerical examples.     

Estimation of nitrogen removal rate in aqueous phase based on delta15N in microorganisms in solid phase

Microbial nitrification and denitrification are important processes for removing nitrogenous compounds in aqueous systems. Nitrogen removal rate estimation is essential for controlling nitrogen removal processes and modeling the nitrogen cycle in ecosystems. The model described the relationship between ammonium removal rate (aqueous phase) and the nitrogen stable isotope ratio (delta15N) of microorganisms (solid phase) when a coupled nitrification-denitrification process occurs and assimilation and advections are maintained in a steady state. An oxidation ditch in a municipal wastewater treatment plant was evaluated for 3 years using the model. The ammonium removal rate was calculated from the data of delta15N of the activated sludge, it correlated significantly with the observed removal rate. The isotope fractionation factor (epsilon) was determined to be -5.5 per thousand by using a nonlinear method. The model and obtained factor value were applicable for standard activated-sludge processes performed in parallel in the oxidation ditch and a river watershed. The model may help illustrate nitrogen behavior in ecosystems.     

CONFORMATIONAL ANALYSIS OF 2-(DIPHENYLPHOSPHANYL)-N,N-DIMETHYL-1-BENZ AMIDE AND 2-(DIPHENYLPHOSPHANYL)-PHENYL-PYRROLIDIN-1-YL-METHANONE BY NMR SPECTROSCOPY

We have synthesized 2-(Diphenylphosphanyl)-N, N-dimethyl-1-benzamide (1) and 2-(Diphenylphosphanyl)- phenyl-pyrrolidin-1-yl-methanone (2), and examined their conformations on the basis of NMR spectral data. Conformational analysis of the compounds is useful in deducing the structure in which they are active as a catalyst. In the present NMR measurements, ¹H-X fg-JHMBC (field gradient J-Resolved Hetero-nuclear Multiple-Bond Correlation) spectroscopy was implemented as a tool for the determination of hetero-nuclear three bond, phosphorus and protons and carbon-protons coupling constants. By fitting a sine curve to the experimental data by the method of 3D J-resolved HMBC NMR measurements, accurate ⁿ J _HX coupling constants were obtained. From the coupling constants, the corresponding dihedral angles, H3-C2-C3-P, H12-C12-C11-P, H16-C16-C11-P, H18-C18-C17-P, and H22-C22-C17-P, of compounds (1) and (2) were determined. The optimized structures of the compounds were obtained by molecular orbital calculations in which the dihedral angles experimentally determined were used.     

铁基合金的液相扩散焊接

本文介绍了用于航天工业的铁基合金－Ｉｎｃｏｌｏｙ８００液相扩散焊接技术，探讨了中间夹层的选择及母材表面合金化的手段，观察分析了焊缝组织及其机械性能。研究表明，中间夹层选择的成功与否是影响液相扩散焊接的主要因素之一。通过试验，找出了中间夹层中硼，碳，硅三种元素的最佳添加量。试验证明，采用激光喷镀法使母材表面合金化的手段是可行的，但镀层底部局部起伏不平导致焊缝形成生成相影响了焊缝的机械性能，通过各种方     

Microfabrication of a Chamber for High-Resolution,In Situ Imaging of the Whole Root for Plant–Microbe Interactions

Fabricated ecosystems (EcoFABs) offer an innovative approach to in situ examination of microbial establishment patterns around plant roots using nondestructive, high-resolution microscopy. Previously high-resolution imaging was challenging because the roots were not constrained to a fixed distance from the objective. Here, we describe a new ‘Imaging EcoFAB’ and the use of this device to image the entire root system of growing Brachypodium distachyon at high resolutions (20×, 40×) over a 3-week period. The device is capable of investigating root–microbe interactions of multimember communities. We examined nine strains of Pseudomonas simiae with different fluorescent constructs to B. distachyon and individual cells on root hairs were visible. Succession in the rhizosphere using two different strains of P. simiae was examined, where the second addition was shown to be able to establish in the root tissue. The device was suitable for imaging with different solid media at high magnification, allowing for the imaging of fungal establishment in the rhizosphere. Overall, the Imaging EcoFAB could improve our ability to investigate the spatiotemporal dynamics of the rhizosphere, including studies of fluorescently-tagged, multimember, synthetic communities.     

A temperature insensitive InGaAsP-InP optical filter

A temperature insensitive optical filter (TIOF) with InGaAsP-InP material system is proposed. Less than 0.1 /spl Aring///spl deg/C temperature dependence is achieved for the first time even though we used the InGaAsP-InP material system. By changing the optimum structure of the TIOF, blue-shift temperature characteristics are also obtained. These two novel phenomena are in good agreement with the TIOF design principle.     

Aging characteristics of InGaAsP/InP DFB lasers

Aging tests of InGaAsP/InP DFB lasers with a constant light output of 5 mW/facet and ambient temperatures 25°C and 40°C have been carried out. Up to the present, with an aging time of more than 2000 h for six lasers, appreciable degradations have been observed in their driving currents and spectra. This indicates that the corrugation grating near the active region has little influence on short-term reliability of DFB lasers.     

Broad-band tunable two-section laser diode with external gratingfeedback

A tunable laser light source consisting of a two-section laser diode and an external grating is discussed. A wide tunable range of 154 nm was realized by improving the antireflection (AR) coating and the coupling efficiency. At both edges of the tunable range, however, the tuning characteristics were strongly influenced by the internal mode, in spite of the high-quality AR coating. The effects of the internal mode were avoided by using a phase-control section of the laser. Consequently, single-mode oscillation can be obtained at any desirable wavelength within the above tunable range by controlling the current injected into the phase-control section     

A wavelength-tunable duplex integrated light source for fastwavelength switching

A new monolithically integrated opto-electronic device has been developed for fast wavelength switching in photonic packet switching. The integrated device, called a tunable duplex integrated light source comprises two distributed Bragg reflector lasers (DBR-LDs), two electroabsorption optical switches, a Y-shaped waveguide coupler, an electroabsorption modulator, and two thermal drift compensators (TDCs). The tuning range of the DBR-LDs is 3 nm, and the wavelength switching time of the optical switches is estimated to be 60 ps including a 50 ps rise time for the electrical pulse generator. The wavelength of a 10 Gb/s NRZ-modulated optical signal is switched without bit loss. Thermal crosstalk between the DBR-LDs, and wavelength drift of the DBR-LDs, which is due to a thermal transient, are effectively suppressed by thermal-drift-compensation operation using the TDCs