Formation of the holographic image of a diffuse object in second-harmonic radiation generated by a nonlinear medium

Results of experiments on recording three-dimensional holographic images of extended diffuse objects using an SHG hologram generating the second harmonic are presented. In this case, the object image is formed by the second-harmonic radiation whose wavelength is smaller than the wavelength of object and reference waves recorded on a hologram by a factor of two. Elements of the theory of an SHG hologram are considered. A holographic image of a transparency object illuminated with diffuse light is obtained. It is shown that the resolving power of this image is close to the limit determined by diffraction effects. An experiment on defocusing the reconstructed image showed that it was localized in one spatial plane and, therefore, was three-dimensional.     

Recording of a hologram by using the second-order nonlinearity

The observation of “spatial-modulation” resonances of saturated absorption in the interaction of iodine-127 vapors with a superposition of frequency-nondegenerate TEM₀₁ and TEM₁₀ transverse modes of a linear laser is reported. The modulation of the total radiation power of the probing wave, recorded at twice the beating frequency of transverse modes of the laser, is interpreted to be the result of the transformation of modulation of the spatial distribution of the field into its amplitude modulation under the action of nonlinearly absorbing iodine vapors. Resonances of saturated absorption of the weak line R(127)11-5 of iodine-127 (633 nm) in an extracavity cell are observed by the method proposed.     

Single Particle Extinction and Scattering allows novel optical characterization of aerosols

We apply to aerosols the optical method of Single Particle Extinction and Scattering recently proposed for characterizing liquid suspensions and specifically adapted to the aim. It provides simultaneous measurements of the real and imaginary parts of the field scattered in the forward direction by single airborne particles passing through a tightly focused laser beam. The intensity of transmitted light is collected in the forward direction, thus realizing a self-reference interferometric scheme relying on the fundamentals of the optical theorem. A high frequency (20 MS/s), extended dynamics (12 bits) sampling is performed by a cheap segmented photodiode, and a specific pulse shape analysis is exploited to validate the signals against a precise mathematical model. We show that accessing two independent physical quantities allows to exploit physical models to recover the aerosol size distribution from the measurement of the refractive index, either real or even complex. Laboratory measurements have been performed with polydisperse aerosols made of water droplets and NaCl in the submicron range, and the system has been accurately characterized. Examples of measurements of graphite nanoparticles and Pyrethrum smoke are shown. Limitations are discussed.     

抗坏血酸有机锗倍半氧化物的合成及抗癌活性研究

通过三氯锗仿与抗坏血酸分子的加成反应,合成了一种新型有机锗倍半氧化物,产物的结构通过元素分析、IR及UV光谱等方法进行了表征．生物活性实验表明合成物对小鼠S-180肿瘤生长具有显著的抑制作用．     

Transferred-NOE NMR experiments on intact human platelets: receptor-bound conformation of RGD-peptide mimics

The aim of this work is to show that transferred-NOE provides useful and detailed information on membrane-bound receptor-ligand interactions in living cells. Here, we study the interaction between intact human platelets and some ligands containing the RGD sequence. Conformational properties of the free and bound pentapeptides are reported.     

Synthesis and Structure of (Bis(1-propylbenzimidazol-2-yl)-trans-1,2-cyclohexane)copper(II) Dichloride and the Structure of a Novel, Unexpected By-Product

Abstract  

Two structures containing the novel ligand bis(1-propylbenzimidazol-2-yl)-trans-1,2-cyclohexane, L, are reported. The first structure, (bis(1-propylbenzimidazol-2-yl)-trans-1,2-cyclohexane)copper(II) dichloride, Cu(II)(L)Cl₂ 1, crystallized in the monoclinic space group P 2₁/n with a = 10.992(4) ?, b = 13.576(5) ?, c = 18.047(7) ?, β = 106.909(8) and V = 2576.7(16) ?³ and Z = 4. Complex 1 exhibits a D _2d-flattened tetrahedral Cu(II)N₂Cl₂ coordination geometry, for which the four-coordinate geometry index τ₄ of 0.59 lies almost midway between the ideal geometry values of zero (square-planar) and 1 (tetrahedral). The second and unexpected structure, (bis(1-hydro-3-propylbenzimidazol-1-ium)-trans-1,2-cyclohexane)(μ⁴-oxo-hexa-(μ²-chloro)-tetra(chloro-copper(II)) di(nitromethane) solvate, 2[H₂L]²⁺[Cu₄OCl₁₀]⁴⁻·(CH₃NO₂)₂, 2, consists of three dimensionally hydrogen bonded bis(benzimidazolium) dications and tetra-copper(II)-oxo-chloride tetra-anions, interspersed with nitromethane solvate molecules. A balanced equation for the formation of the byproduct suggests that it forms via an acid–base reaction in the presence of water in the reaction mixture. The complex crystallized in the triclinic space group P −1 with a = 13.696(3) ?, b = 13.819(3) ?, c = 16.797(4) ?, α = 89.480(4), β = 87.308(4)°, γ = 89.434(4) and V = 3175.3(12) ?³ and Z = 2. Ligand L contains two stereogenic centers, each of the same handedness, and, since the space groups determined for structures 1 and 2 are centrosymmetric, both structures are racemates.     

Routine analysis by high precision gas chromatography/mass selective detector/isotope ratio mass spectrometry to 0.1 parts per mil

Stable isotope methods are potentially quite useful for validating natural or enhanced mineral degradation of contaminants. For this reason, a continuous flow gas chromatograph (GC), isotope ratio mass spectrometer (IRMS) has been coupled with a quadrupole mass selective detector (MSD) to allow simultaneous mass spectral and stable carbon isotope ratio data to be obtained from a single chromatographic analysis. This allows the target contaminant and any extra-cellular degradation intermediates to be both qualified and quantified. Previously acceptable limits of precision (0.3 parts per mil) are undesirable given the small fractionation observed during aerobic degradation. To further understand the fate of organic contaminants and to gain information about the metabolic degradative pathway employed by a microorganism, routine isotopic analyses on a range of analytes have been performed. Quantities of sample producing mass-44 ion beam signal (I(44)) of 2 x 10(-10) to 1 x 10(-8) A were analysed. When the IRMS was tuned for high sensitivity, ion source nonlinearities were overcome by peak height correction from an algorithm that was produced using known isotopic standards of varying concentrations. This led to sample accuracy of <0.01 per thousand and sample precision of 0.1 per thousand. Copyright 1999 John Wiley & Sons, Ltd.