多光子光学双稳性的复振幅解析分析

本文应用线性化稳定性分析方法,对用半经典的麦克斯韦-布赫(Maxwell-Bloch)方程描述的多光子光学双稳性进行了复振幅分析.分析的结果表明:在对极化量进行绝热消除后,多光子光学双稳性特性曲线上合作支和单原子支不存在失稳问题,同时说明由软模不稳定性引起的多光子光学双稳性的混沌态不存在,并指出稳定性的第三个条件是双稳性存在的条件.     

Bromination of methyl substituted 1,2,5-thiadiazoles with N-bromosuccinimide

Bromomethyl-1,2,5-thiadiazoles 2a-c were prepared by bromination of methyl-1,2,5-thiadiazoles 1a-c by NBS in refluxing carbon tetrachloride. When bromination of 1a and 1b was carried out under irradiation of tungusten lamp, mixtures of cis -5a and b and trans-1,2-dibromo-1,2-bis(1,2,5-thiadiazol-3-yl)ethylene ( 6a and b ) were obtained.     

Iodine-123 production at a small cyclotron for medical use

An improved method has been developed to obtain highly enriched [¹²³Te] tellurium for the production of medically important¹²³I. Excitation function of the¹²³Te(p,n)¹²³I reaction, production yields and radionuclidic impurity levels were determined as a function of bombarding energy and target thickness.     

A convenient and one-pot synthesis of 9-substituted carbazoles from primary amine hydrochlorides and 2,5-dimethoxytetrahydrofuran

Carbazoles are the very important compounds in material science, nevertheless conventional syntheses required severe and complicated reaction conditions. In the process of preparation of pyrrole derivatives, we found that a primary amine hydrochloride 1 and 2,5-dimethoxytetrahydrofuran 2 were refluxed in a benzenewater (100:4 (v/v)) mixture to be obtained 9-substituted carbazole 5 in a high yield. This method is the one-pot synthesis of 9-substituted carbazoles 5 under mild and convenient conditions.     

Multispectral incoherent holography based on measurement of differential wavefront curvature

Optical Review - We propose a technique of multispectral incoherent holography. The differential wavefront curvature is measured, and the principle of Fourier transform spectrometry is applied to...     

Nonlinear effects on solvation dynamics in simple mixtures

The authors applied the time dependent density functional method (TDDFM) and a linear model to solvation dynamics in simple binary solvents. Changing the solute-solvent interactions at t=0, the authors calculated the time evolution of density fields for solvent particles after the change (t>0) by the TDDFM and linear model. First, the authors changed the interaction of only one component of solvents. In this case, the TDDFM showed that the solvation time decreased monotonically with a mole fraction of the solvent strongly interacting with the solute. The monotonical decreases agreed with experimental results, while the linear model did not reproduce these results. The authors also calculated the solvation time by changing the interaction of both components. The calculation showed that the mole fraction dependence had the peak. The TDDFM presented a much higher peak than the linear model. The difference between the TDDFM and the linear model was caused by a nonlinear effect on an exchange process of solvent particles.     

Adsorption of unsaturated hydrocarbon moieties on H:Si(111) by Grignard reaction

Grafting of unsaturated hydrocarbon moieties (-CH(2)-CH=CH(2), -CH=CH(2), -CH(2)-CH=CH-CH(3), and -CCH) by a C-Si covalent bond was attempted by the Grignard reaction on hydrogen-terminated Si(111) in tetrahydrofuran solutions. The product adsorbates were monitored by vibrational methods of high-resolution electron energy loss spectroscopy and multiple internal infrared reflection absorption spectroscopy, as well as Auger electron spectroscopy. The temperature and the period of reaction were adjusted so as to preserve the unsaturated carbon-carbon bonds. The -CH(2)-CH=CH(2) group was introduced by a mild reaction condition, with the reservation of the C=C double bond confirmed. The unsaturated bonds in -CH(2)-CH=CH-CH(3) and -CCH were also reserved. Only in the case of -CH=CH(2) was the reservation of the C=C double bond not realized. Unsaturated hydrocarbon moieties are applicable for further organic modification to introduce functional groups, and are prospective materials in nanofabrication and biological application on silicon wafer surfaces.     

The chemisorption of spin polarised NO on Ag{111}

Spin-density functional theory calculations are presented for NO adsorbed on Ag{111}. The ground state for the monomeric species is chemisorbed in an upright configuration, but retains 90% of the spin-density of the free molecule, in the molecular 2π^* orbital. In constrast, two NO molecules in upright configuration chemisorbed at neighbouring fcc and hcp sites have zero spin-density, and charge density difference plots demonstrate π bonding as in the free dimer, (NO)₂.     

A Palladium‐Catalyzed Carbonylation Approach to Eight‐Membered Lactam Derivatives with Antitumor Activity

The reactivity of 2‐(2‐alkynylphenoxy)anilines under PdI₂/KI‐catalyzed oxidative carbonylation conditions has been studied. Although a different reaction pathway could have been operating, N‐palladation followed by CO insertion was the favored pathway with all substrates tested, including those containing an internal or terminal triple bond. This led to the formation of a carbamoylpalladium species, the fate of which, as predicted by theoretical calculations, strongly depended on the nature of the substituent on the triple bond. In particular, 8‐endo‐dig cyclization preferentially occurred when the triple bond was terminal, leading to the formation of carbonylated ζ‐lactam derivatives, the structures of which have been confirmed by XRD analysis. These novel medium‐sized heterocyclic compounds showed antitumor activity against both estrogen receptor‐positive (MCF‐7) and triple negative (MDA‐MB‐231) breast cancer cell lines. In particular, ζ‐lactam 3 j′ may represent a novel and promising antitumor agent because biological tests clearly demonstrate that this compound significantly reduces cell viability and motility in both MCF‐7 and MDA‐MB‐231 breast cancer cell lines, without affecting normal breast epithelial cell viability.