Enantiomeric Discrimination by Surface‐Enhanced Raman Scattering–Chiral Anisotropy of Chiral Nanostructured Gold Films

A surface‐enhanced Raman scattering‐chiral anisotropy (SERS‐ChA) effect is reported that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films (CNAFs) equipped in the normal Raman scattering Spectrometer. The CNAFs provided remarkably higher enhancement factors of Raman scattering (EFs) for particular enantiomers, and the SERS intensity was proportional to the enantiomeric excesses (ee) values. Except for molecules with mesomeric species, all of the tested enantiomers exhibited high SERS‐ChA asymmetry factors (g), ranging between 1.34 and 1.99 regardless of polarities, sizes, chromophores, concentrations and ee. The effect might be attributed to selective resonance coupling between the induced electric and magnetic dipoles associated with enantiomers and chiral plasmonic modes of CNAFs.     

外部边界球可达域上拟共形映射的Lipschitz连续性

定义了外部边界球可达域,利用曲线族的模获得如下结果:设D是R~n中的有界拟凸域,f:D→B~n是K-拟共形映射,若D是外部边界球可达域,则f∈Lip_α(D),其中α=K~(1/(1-n)).     

一种新型温湿度测量系统的设计

为了解决传统温湿度测量系统存在的标定和校准过程复杂而引起的精度不高的问题,文中介绍了一种新型的温湿度测量系统。该系统由瑞士SENSIR ION公司新生产的SHT11数字式温湿度传感器和日本NEC公司生产的78F9177Y单片机为核心组成,具有电路简单、免标定、精度高和可靠性好等优点。     

基于FPGA的DDS设计方法

介绍了一种基于FPGA的DDS设计方法,结合DDS的原理,给出了具体设计程序以及仿真波形。基于FPGA的DDS与传统的专业DDS芯片相比具有电路简单、输出波形调整灵活以及性价比高等特点。     

Three New Isoprenylated 2‐Arylbenzofurans from Artocarpus petelotii

Three new isoprenylated 2‐arylbenzofurans, artopetelins A–C ( 1 – 3 ), were isolated as minor constituents from the EtOH extract of the root barks of Artocarpus petelotii Gagnep . Their structures were elucidated by spectroscopic methods, including HR‐EI‐MS and 2D‐NMR techniques.     

Three Octacyanometallate‐Based LnIII–MV (Ln = La,Ce; M = Mo,W) Bimetallic Assemblies with a One‐Dimensional Rope‐Ladder Chain Structure

Three octacyanometallate‐based hetero‐bimetallic complexes, [Ln(H₂O)₄(CH₃CN)₂][M(CN)₈] · CH₃CN [Ln = La, M = Mo( 1 ), W( 2 ); Ln = Ce, M = W( 3 )], were synthesized and characterized structurally. Single‐crystal X‐ray analysis reveals that 1 – 3 are isomorphous and consist of infinite one‐dimensional (1D) 3,3 rope‐ladder chains, in which the 12‐membered puckered square Ln₂M₂(CN)₄ is the basic building unit. The 1D chains are further linked through interchain hydrogen bonds, resulting in a three‐dimensional (3D) supramolecular network.     

Improved free space optical communications performance by using time diversity

A laser beam propagating through turbulence experiences random amplitude and phase fluctuations, which can severely degrade the performance of free space optical communication systems. It this letter, time diversity is demonstrated as a technique which can decrease turbulence influence. Statistically, laser propagation along an atmospheric path is uncorrelated with an earlier-time path for a time interval greater than the atmospheric turbulence correlation time. To estimate time diversity system performance, a 2.2-km optical link is set up for comparing the fade probability of a system using time diversity with a system not using time diversity. The experimental results obtained under different turbulence conditions are shown which are in good agreement with the theory.     

Asymptotic behaviour of multiperiodic functions scaled by Pisot numbers

Let β > 1 be a Pisot number andg be a positive Hölder continuous function with period one and g(0) = 1. The multiperiodic functionG(ξ)=Π _n=0 ^∞ g(ξ/βⁿ) is studied and the asymptotic behaviour ofI _G(T) = ∫ ₀ ^T G(ξ)dξ investigated. We prove that the limit of logI(T)/ logT exists asT tends to infinity. We also provide a method to calculate this limit for the caseg(ξ) = cos² 2πξ, corresponding to the Fourier transform of the Bernoulli convolution associated to the golden number (or some of its generalizations).     

Stable conformations of 12-crown-O3N and its Li+ complex in aqueous solution

Stable conformations of 12-crown-O3N and its Li complexes in aqueous solution were investigated. To calculate the free energy differences of conformers of 12-crown-O3N and its Li+ complex, our procedure was to make use of two programs, CONFLEX and BOSS. The former generates conformers, and the latter calculates the differences in free energy of solvation between two conformers in aqueous solution. It was confirmed that the present procedure is applicable in solving the question of what is the most stable conformation of 12-crown-O3N in aqueous solution. Results of the calculations suggest that the order of stability for conformers in a vacuum is different from that in aqueous solution. It was also confirmed that the coordination geometry of solvent waters to Li+ changes depending on the distance between the cation and the crown ring.