Synthesis and optical properties of N-In codoped ZnO nanobelts

N-In codoped ZnO nanobelts were successfully synthesized via high-temperature chemical vapor deposition for the first time, using the mixture of In/ZnO as a precursor. The EDX spectrum showed that In was introduced into ZnO nanobelts. In order to better understand the optical properties of N-In codoped ZnO nanobelts, the Raman and low-temperature PL spectra of the undoped, In-doped and N-In codoped ZnO nanostructures were measured. By contrasting, N is incorporated into the nanobelts. The temperature dependent photoluminescence (PL) spectra were investigated. Their PL spectra in the temperature from 9 K to room temperature were dominated by an A^oX emission of excitons bound to 2No-In_Zn acceptor complexes. The dissociation energy of the acceptor complexes is estimated to be 89-112 meV.     

TiO_2一维纳米材料及其纳米结构的合成

本文对合成TiO2一维纳米材料及其有序纳米阵列的阳极氧化法、模板法以及水热法进行了全面而系统的评述,着重介绍了它们的最新研究进展。阳极氧化法能制备牢固负载于基体上的TiO2纳米管阵列,这有助于构筑TiO2纳米结构及其在纳米器件上的应用;与多种制备技术如溶胶-凝胶工艺、电化学沉积以及原子层沉积等相结合,模板法可以合成出多种形貌的TiO2纳米材料如纳米管、纳米线和纳米棒,并且可以通过改变所用模板的微观尺寸来调控TiO2一维纳米材料及其有序阵列的微结构参数;水热合成法可以制备出直径小且比表面积大的TiO2纳米管粉末。从目前来看,该法还不能制备出牢固负载于基体上的有序纳米阵列。文章最后指出了TiO2一维纳米材料及其有序纳米阵列合成中存在的问题及今后发展方向。     

Room‐temperature Suzuki–Miyaura cross‐coupling reaction with α‐diimine Pd(II) catalysts

An α‐diimine Pd(II) complex containing chiral sec‐phenethyl groups, {bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dichloropalladium (rac‐ C1 ), was synthesized and characterized. rac‐ C1 was applied as an efficient catalyst for the Suzuki–Miyaura cross‐coupling reaction between various aniline halides and arylboronic acid in PEG‐400–H₂O at room temperature. Among a series of aniline halides, rac‐ C1 did not catalyze the cross‐coupling of aniline chlorides and fluorides but efficiently catalyzed the cross‐coupling of aniline bromides and iodides with phenylboronic acid. The catalytic activity reduced slightly with increasing steric hindrance of the aniline bromides. The complexes {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]‐2,3‐butadiene}dichloropalladium and {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]acenaphthene}dichloropalladium were also found to be efficient catalysts for the reaction. Copyright © 2015 John Wiley & Sons, Ltd.     

空气冲击波重复作用的生物效应

实验动物为体重15.2～42.4kg的绵羊和山羊共46只。用TNT化爆和BST-Ⅰ型激波管致伤,伤后6小时进行形态学检查,以确定重复冲击的效应。结果表明多次重复冲击可使损伤显示累加效应,表现为损伤的发生率和程度增加,损伤阈值降低。     

Electrochemical Behavior of Calcein and the Interaction Between Calcein and DNA

The electrochemical behavior of calcein (CA) has been investigated by using a conductive carbon black paste electrode (CCBPE) as working electrode. It exhibits a single well‐defined redox peak in phosphate buffered saline in the range of pH 5.5–8.0, which attributes to the irreversible oxidation with 2 electrons and 2 protons participation. Under the optimized analytical conditions, the proposed linear sweep voltammetry (LSV) method allows the determination of CA in a linear concentration range of 0.64–9.60 µM, with a limit of detection of 0.32 µM. Further, the interaction between CA and DNA were studied by voltammetric and spectrometric methods. Both studies have shown that CA can bind to DNA by the intercalation binding mode. Under the present experimental condition, the binding constant β of CA and dsDNA is 1.10×10⁷. Meanwhile, in the loop‐mediated isothermal amplification (LAMP) reaction mixture there is obvious interaction between CA and dsDNA, resulting in a nonignorable decrease of the indicating sensitivity.     

Green synthesis by diethylene glycol based solution process and characterization of SnS nanoparticles

Uniform near‐spherical SnS nanoparticles were prepared by a hydrazine hydrate‐assisted diethylene glycol solution synthesis based on the reaction of tin dichloride (SnCl₂·2H₂O) with thioacetamide (H₃CCSNH₂). The as‐prepared SnS nanoparticles were characterized by XRD, FETEM, EDS, XPS and UV‐vis‐NIR spectrophotometer. The results showed that the SnS nanoparticles had orthorhombic crystal structure, good stoichiometry and indirect bandgap of ∼1.1 eV. The nanoparticle size could be controlled by changing injection temperature. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Formation of single-crystalline TiO2 nanomaterials with controlled phase composition and morphology and the application in dye-sensitized solar cell

Single-crystalline TiO₂ nanomaterials with controlled phase composition and morphology were synthesized by hydrothermal transformation of H-titanate nanotubes under different pH. Rutile rectangle nanorods with two four-side tapered tips were produced at pH of 0, whereas anatase nanoparticles with mainly of rhombic shape were obtained at pH from 2 to 7 and their average particle size increased with pH. The transformation mechanisms at different pH were discussed. The single-crystalline anatase nanoparticles obtained at pH of 2 had ca. 12 nm in average particle size, and the powder possessed as large as 112 m²/g specific surface areas; the conversion efficiency of the dye-sensitized solar cell based on the nanoparticles was increased by over 40% as compared with that of the cell based on P25.     

Chaotic secure communication based on strong tracking filtering

A scheme for implementing secure communication based on chaotic maps and strong tracking filter (STF) is presented, and a modified STF algorithm with message estimation is developed for the special requirement of chaotic secure communication. At the emitter, the message symbol is modulated by chaotic mapping and is output through a nonlinear function. At the receiver, the driving signal is received and the message symbol is recovered dynamically by the STF with estimation of message symbol. Simulation results of Holmes map demonstrate that when message symbols are binary codes, STF can effectively recover the codes of the message from the noisy chaotic signals. Compared with the extended Kalman filter (EKF), STF has a lower bit error rate.     

Catalytic Synthesis of a Monodisperse Olefin Block Copolymer Using a Living Polymerization System

Polymerization of norbornene has been conducted with [t‐BuNSiMe₂(3,6‐t‐Bu₂Flu)]TiMe₂ ( 1 ) in toluene at 20 °C using modified methylaluminoxane that contained 0.4 mol‐% of triisobutylaluminium (TIBA) (dMMAO(0.4)) or 1.8 mol‐% of TIBA (dMMAO(1.8)). The 1 ‐dMMAO(0.4) catalytic system undergoes a living polymerization of norbornene. The catalysis of norbornene and propylene with the 1 ‐dMMAO(1.8) catalytic system gives markedly different results because of differences in transfer times of the polymers from Ti to TIBA. The successive addition of norbornene and propylene before the complete consumption of the norbornene in the 1 ‐dMMAO(1.8) system gives monodisperse PNB‐block‐poly(propylene‐ran‐norbornene)‐block‐PP terminated with a Ti–PP bond, which is exchanged with TIBA. Hence the repeated addition of the same amount of norbornene and propylene realizes the catalytic synthesis of monodisperse block copolymer in this system.

     

ON THE METRICS OF THE RIEMANNIAN MANIFOLDS WHICH ADMIT ISOMETRIC IMBEDDING INTO SPACE OF ANY CONSTANT CURVATURE

In this paper the term“Riemannian manifold”means that the fundamental quadraticdifferential form may be indefinite.