Synthesis and transition temperatures of liquid crystals incorporating a 1,4-tetrafluorophenylene unit

Two homologous series of mesogenic materials which incorporate a 1,4-tetrafluorophenylene moiety and a terminal cyano- or nitro-substituent have been synthesized by using palladiumcatalysed coupling procedures. The compounds exhibit nematic and/or smectic A phases.     

First observation of yrast band in odd-odd162Lu

High spin states of the odd-odd¹⁶²Lu nucleus have been studied via¹⁴⁷Sm(¹⁹F,4nγ)¹⁶²Lu reaction at 95 MeV beam energy. Level scheme for yrast band based onπ[h_11/2 v[i_13/2] quasiparticle configuration was established up to I ^π = (23^?) for the first time. This band shows the signature inversion in energy before backbending generally appeared in this mass region. It is stressed that the signature splitting in¹⁶²Lu is larger than that in the¹⁶⁰Tm nucleus.     

ROOM TEMPERATURE LIGHT-THERMO-DETECTOR MADE OF HIGH-Tc SUPERCONDUCTOR

Based on the anisotropic Seebeck tensor coefficients, a light-thermo-radiation detector made of high-T_c superconductor (YBa₂Cu₃O_7-δ) was fabricated, which can function at room temperature. The induced voltaic signals at various modulation frequencies for radiation from He-Ne laser and from a 500 K black body were measured. The noise ratio for detecting He-Ne laser radiation and the D^* for black body were evaluated. Compared with bolometer made of high-T_c superconductor which functions at liquid nitrogen, and with pyroelectric detector, it was found that the advantages of this new device are that the device can work at room temperature with very low noise and very fast response. Although having a lower D^* value than that of bolometer for the present device construction, we point out the possibility and the direction for improving the D^* value, hence the promising prospect of this kind of device.     

Mean Value on the Difference Between a Quadratic Residue and Its Inverse Modulo p

The main purpose of this paper is to use the generalized Bernoulli numbers, Gauss sums and the mean value theorems of Dirichlet L-functions between a quadratic residue and its inverse modulo p value formula. to study the asymptotic property of the difference （a prime）, and to give an interesting hybrid mean     

The Problem of Periodic Solutions for a Class of Dynamical System（Ⅱ）

51.IntroductionLetK:R"XR"-Rbeasmoothfunctionwithi)K(q,p)isevenandstrictlyconvexinP,VqeR"lii)K(q,6)=o,VqeR".Supl>oseV=R"-Rbeasmoothfunction,t:R"-R"'(,n<)l)beaSubmersiveoperator.WIlereR",R,.arendimensionalEducli(leanspace,qeR",PeR",C(q)=(C,(q),C,(q),-.'C.,(q)).DenoteH(q,p)=K(q,p) V(q).Throughoutthispaper,weletZ(=(q,p))=6betheequilibriumpointofthefollowingsystem-ForoperatorC,wedefinethespeedoperatorofCisWhere,CisconsideredCorr,rristl1e1>rojeclionoperatorfromR"XR,,toI{.,anddf(z)…     

Syntheses,crystal structures and blue emission of three zinc(II) coordination polymers with a 4,4′‐dicarboxybiphenyl sulfone ligand

Three novel zinc complexes [Zn(dbsf)(H₂O)₂] ( 1 ), [Zn(dbsf)(2,2′‐bpy)(H₂O)]·(i‐C₃H₇OH) ( 2 ) and [Zn(dbsf)(DMF)] ( 3 ) (H₂dbsf = 4,4′‐dicarboxybiphenyl sulfone, 2,2′‐bpy = 2,2′‐bipyridine, i‐C₃H₇OH = iso‐propanol, DMF = N,N‐dimethylformamide) were first obtained and characterized by single crystal X‐ray crystallography. Although the results show that all the complexes 1–3 have one‐dimensional chains formed via coordination bonds, unique three‐dimensional supramolecular structures are formed due to different coordination modes and configuration of the dbsf^2? ligand, hydrogen bonds and π–π interactions. Iso‐propanol molecules are in open channels of 2 while larger empty channels are formed in 3 . As compared with emission band of the free H₂dbsf ligand, emission peaks of the complexes 1–3 are red‐shifted, and they show blue emission, which originates from enlarging conjugation upon coordination. Copyright © 2006 John Wiley & Sons, Ltd.     

动力系统简介

本文对动力系统这一学科的历史、理论、应用以及与其他学科的联系作一简介.