双色反射技术在温度测量上的应用

本文以铁镍合金为例,介绍了一种测量金属表面温度的光学测量方法。试验以黑体为反射辐射源,采用FTIR光谱辐射计测量了试样在中温状态的发射辐射以及包含了黑体反射能量的有效辐射。通过建立包含反射辐射的方程组,并运用MATLAB内建的求根模型求解得到了试样表面温度。     

一种高效便捷的红外探测卡

我们利用稀土直接掺杂工艺 ,通过向带隙宽为 4～ 5ｅＶ的ⅡＡ ⅥＡ族化合物中掺入稀土离子Ｅｕ、Ｓｍ ,合成了电子俘获材料 (ＥＴＭ ＥｌｅｃｔｒｏｎＴｒａｐ ｐｉｎｇＭａｔｅｒｉａｌ)ＣａＳ :Ｅｕ ,Ｓｍ。该材料具有红外上转换和光存储特性 ,其红外响应光谱宽 ( 0 .8～ 1 .6μｍ)、量子转换效率高达 76% [1 ,2 ] 、热稳定性好、使用方便 (室温下工作 ,不需制冷 )、造价低 ,并且具有“常光充能”特性 ,即不需紫外线预激发就能在室温下将红外光 ( 0 .8～ 1 .6μｍ)直接转换为醒目的可见红光 ,是一种优良的红外探测材料 ,利用该材料制作的…     

Models for the active site in galactose oxidase: Structure, spectra and redox of copper(II) complexes of certain phenolate ligands

Galactose oxidase (GOase) is a fungal enzyme which is unusual among metalloenzymes in appearing to catalyse the two electron oxidation of primary alcohols to aldehydes and H₂O₂. The crystal structure of the enzyme reveals that the coordination geometry of mononuclear copper(II) ion is square pyramidal, with two histidine imidazoles, a tyrosinate, and either H₂O (pH 7.0) or acetate (from buffer,pH 4-5) in the equatorial sites and a tyrosinate ligand weakly bound in the axial position. This paper summarizes the results of our studies on the structure, spectral and redox properties of certain novel models for the active site of the inactive form of GOase. The monophenolato Cu(II) complexes of the type [Cu(L1)X][H(L1) = 2-(bis(pyrid-2-ylmethyl)aminomethyl)-4-nitrophenol and X⁻ = Cl⁻ 1, NCS⁻ 2, CH₃COO⁻ 3, ClO₄ ⁻ 4] reveal a distorted square pyramidal geometry around Cu(II) with an unusual axial coordination of phenolate moiety. The coordination geometry of 3 is reminiscent of the active site of GOase with an axial phenolate and equatorial CH₃COO⁻ ligands. All the present complexes exhibit several electronic and EPR spectral features which are also similar to the enzyme. Further, to establish the structural and spectroscopic consequences of the coordination of two tyrosinates in GOase enzyme, we studied the monomeric copper(II) complexes containing two phenolates and imidazole/pyridine donors as closer structural models for GOase. N,N-dimethylethylenediamine and N,N’-dimethylethylenediamine have been used as starting materials to obtain a variety of 2,4-disubstituted phenolate ligands. The X-ray crystal structures of the complexes [Cu(L5)(py)], (8) [H₂(L5) = N,N-dimethyl-N’,N’-bis(2-hydroxy-4-nitrobenzyl) ethylenediamine, py = pyridine] and [Cu(L8)(H₂O)] (11), [H₂(L8) = N,N’-dimethyl-N,N’-bis(2-hydroxy-4-nitrobenzyl)ethylenediamine] reveal distorted square pyramidal geometries around Cu(II) with the axial tertiary amine nitrogen and water coordination respectively. Interestingly, for the latter complex there are two different molecules present in the same unit cell containing the methyl groups of the ethylenediamine fragmentcis to each other in one molecule andtrans to each other in the other. The ligand field and EPR spectra of the model complexes reveal square-based geometries even in solution. The electrochemical and chemical means of generating novel radical species of the model complexes, analogous to the active form of the enzyme is presently under investigation.     

Synthesis,characterization and spectroscopic studies of pyrazinamide metal complexes

The present paper deals with the synthesis and characterization of Schiff base complexes of pyrazinamide an antitubercular drug. Metals selected for complexation are copper, silver, gold, zinc, mercury, iron and cobalt. The complexes have been suitably synthesized and isolated in pure powdered form. Analytical data agrees with the compositions M(L), M′(L)₂ and M″(L)₂·2H₂O, respectively where M = Ag, M′ = Cu, Au, Zn and Hg and M″ = Fe and Co, ligand metal ratios were also confirmed by monovariation method and Job’s method of continuous variation. Molar conductance values suggest the non ionic nature of the complexes. The tentative structure assigned to the complexes on the basis of stoichiometry and analytical data were further supported by spectral studies viz; IR, NMR, magnetic susceptibility and electronic spectra. A preliminary attempt has also been made to compare the potencies of metal complexes with parent drug. The Cu and Ag complexes are giving encouraging results. Particle size studies further suggest that the drug molecule undergoes reduction in size on complexation.     

Unquenched Effects and Quark Mass Dependence of Lattice Gluon Propagator in Infrared Region

In this paper, the gluon propagator in Landau gauge has been studied on a lattice, including the quenched and the unquenched one. The small geometry size of lattice we use is 16^3 × 32, and the big one is 20^3 × 64. For the quenched approximation, we fit the numerical results and give a little different fitting values. We also obtain unquenched effects by comparing the gluon propagator resulting from the quenched and unquenched configurations, for both the two-flavor and three-flavor cases. For the unquenched configurations, an obvious quark mass dependence has not been found in the small quark mass case, but is found in the three-flavor case when the quark mass is big.     

Spectral Semi-discretisations of Weakly Non-linear Wave Equations over Long Times

The long-time behaviour of spectral semi-discretisations of weakly non-linear wave equations is analysed. It is shown that the harmonic actions are approximately conserved for the semi-discretised system as well. This permits to prove that the energy of the wave equation along the interpolated semi-discrete solution remains well conserved over long times and close to the Hamiltonian of the semi-discrete equation. Although the momentum is no longer an exact invariant of the semi-discretisation, it is shown to be approximately conserved. All these results are obtained with the technique of modulated Fourier expansions. Dedicated to Professor Arieh Iserles on the Occasion of his Sixtieth Birthday.     

用显微金刚石池测试高分子弹性材料的红外光谱

本文论述了用显微金刚石池研究高分子弹性材料，方法简便、快速和精确。     

HREELS investigation of hydrogenated and deuterated GaN{0001} surfaces

The vibrational properties of clean, H- and D-covered GaN{0001} surfaces were investigated by high-resolution electron energy-loss spectroscopy. Auger electron spectroscopy and low-energy electron diffraction were utilized to monitor the surface cleanliness and structure, respectively. At the clean surface the Fuchs-Kliewer surface phonon frequency was determined to 700 cm^-1 (86.8 meV). For the adsorbate-covered surfaces current structure models predict only Ga-H vibrations for surfaces of either polarity. Despite of this, the HREEL-spectra of the hydrogenated sample show a new loss structure at 3255 cm^-1 (403.6 meV) and a shoulder at 1900 cm^-1 (235.6 meV) which are attributed to N-H and Ga-H stretching vibrations, respectively. After deuterium exposure an isotope shift occurs. Again, a N-adsorbate vibration is clearly resolved. A Ga-D bending mode is observed at 390 cm^-1 (48.4 meV), indicating that vibrations of both species are present. Received 1 February 2000     

Recent advances in lattice gauge theories

Recent progress in the field of lattice gauge theories is briefly reviewed for a nonspecialist audience. While the emphasis is on the latest and more definitive results that have emerged prior to this symposium, an effort has been made to provide them with minimal technicalities.