基于瑞利积分叠加法的聚焦换能器声场特性研究

基于经典的瑞利积分,提出考虑非线性传播、各次谐波衰减的声场瑞利积分线性叠加算法.分析其原理,并以凹球面聚焦换能器为例,采用该算法研究媒质衰减和非线性传播特性影响声焦域的规律.并与Khokhov-Zabolotskaya-Kuznesov(KZK)数值算法,以及实验结果进行比较,验证瑞利积分线性叠加算法描述高强度聚焦超声(HIFU)声场的有效性.     

新显色剂N－辛基－N＇－（氨基对苯磺酸钠）硫脲（OPT）与铜（Ⅱ）显色反应的研究和应用

Ｎ－辛基－Ｎ＇－（氨基对苯磺酸钠）硫脲是新合成的一种显色剂，该试剂极易溶于水而形成无色溶液。在ｐＨ３．６～５．２的ＨＡｃ－ＮａＡｃ缓冲体系中，试剂与铜（Ⅱ）形成一种稳定的蓝色水溶性配合物，其组成比为：Ｃｕ（Ⅱ）：ＯＰＴ＝１：３。配合物的最大吸收波长位于３０１．４ｎｍ，表观摩尔吸光系数ε＿（３０１．４）＝１．８２×１０￣５Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１）。Ｃｕ（Ⅱ）在０～１０μｇ／２５ｍＬ服从比尔定律，相关系数ｒ＝０．９９９６，方法的检出限为３．８５×１０￣（－９）ｇ／ｍＬ。本法灵敏度高，选择性好、操作简单，可直接在水相中测定。将本法用于合金钢和生物制品中微量铜的测定，均获得满意结果。     

Nitrosonium (NO) initiated and cation radical-mediated imino Diels-Alder reaction

An efficient aza-Diels-Alder reaction of N-arylimines with N-vinylpyrrolidinone was achieved using nitrosonium tetrafluoroborate as a cation radical initiator, giving cis-4-(2-oxopyrrolidin-1-yl)tetrahydroquinolines in various yields.     

Size‐ and Halide‐Dependent Auger Recombination in Lead Halide Perovskite Nanocrystals

Lead halide perovskite nanocrystals (NCs) hold strong promise for a variety of light‐harvesting, emitting, and detecting applications, all of which, however, could be complicated by multicarrier Auger recombination. Therefore, complete documentation of the size‐ and composition‐dependent Auger recombination rates of these NCs is highly desirable, as it can guide system design in many applications. Herein we report the synthesis and Auger measurements of monodisperse APbX₃ (A=Cs and FA; X=Cl, Br, and I) NCs in an extensive size range (ca. 3–9 nm). The biexciton Auger lifetime of all the NCs scales linearly with the NC volume. The scaling coefficient is virtually independent of the cation but rather depends sensitively on the anion, and is 0.035, 0.085, and 0.142 ps nm^?3 for Cl, Br, and I, respectively. In all of these nanocrystals the Auger recombination is much faster than in standard CdSe and PbSe NCs (ca. 1 ps nm^?3).     

Two-Phase Dehydrogenation of Aryl Substituted Carbazide Compounds

Two-phase dehydrogenation, which is a new reaction of aryl substituted carbazide compounds, is described in this paper. Ten new azo compounds were synthesized by the reaction of aryl substituted carbazide compounds with a phenoxyl radical between two phases in good yields.     

SPSS软件对铁矿中微量元素含量的统计分析

利用SPSS软件从统计学描述、正态分布检验、回归和相关分析、聚类分析和因子分析等方面对铁矿中微量元素含量特点进行了研究。分析结果表明:根据抽样样本,铁矿中11种微量元素含量均不符合正态分布特征,异常值分布矿种相对集中,重金属和硫及卤素之间的相关程度高,同时根据因子综合得分对矿种进行了分类,为铁矿品质评价和合理利用提供了一定的参考。     

Doubly Periodic Wave Solutions and Soliton Solutions of Ablowitz–Ladik Lattice System

The general Jacobi elliptic function expansion method is developed and extended to construct doubly periodic wave solutions for discrete nonlinear equations. Applying this method, many exact elliptic function doubly periodic wave solutions are obtained for Ablowitz–Ladik lattice system. When the modulus m→1 or m→0, these solutions degenerate into hyperbolic function solutions and trigonometric function solutions respectively. In long wave limit, solitonic solutions including bright soliton and dark soliton solutions are also obtained.     

N-+-烷基-N''-(对氨基苯磺酸钠)硫脲光度法测定铜

研完了新显色剂长链饱和脂肪烃取代基化合物(UPT)和微量Cu2+反应。试验表明，在pH 5.2～5.6的乙酸－乙酸钠介质中,Cu2+与试剂形成摩尔比为13的淡黄绿色稳定络合物，其最大吸收为 300.4nm，表观摩尔吸光系数为ε300.4nm＝2.39×105L·mol·cm-1。铜浓度在2～12μg/25m1的范围内符合比耳定律，相关系数r＝O.9990。方法简便、灵敏，应用于样品测定，结果满意。     

Grafting modification and structural degradation of multi-walled carbon nanotubes under the effect of ultrasonics sonochemistry

Polyvinyl pyrrolidone (PVP) grafted multi-walled carbon nanotubes (MWCNTs) were prepared by the degradation effect of ultrasonics sonochemistry. PVP macroradicals formed by sonochemical degradation of a PVP solution were trapped by MWCNTs and grafted onto the surface of MWCNTs. It was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis that the PVP was covalently bonded on the MWCNTs. Transmission electron microscopy showed nanotubes in the grafted samples were shorter than the original MWCNTs due to the crushing effect of ultrasonics sonochemistry. Both the decrease in length of the MWCNTs and the PVP grafted onto them are beneficial for their dispersion in solvents.     

In situ synthesis of a novel transparent poly (methyl methacrylate) resin with markedly enhanced flame retardancy

A novel phosphorus‐containing monomer, (6‐oxido‐6H‐dibenzo[c,e][1,2]oxaphosphinin‐6‐yl)methyl acrylate (DOPO‐AA), is first synthesized and characterized by Fourier transform infrared spectra (FTIR), ¹H nuclear magnetic resonance (NMR) and ³¹P NMR. The monomer is then introduced into poly (methyl methacrylate) (PMMA) matrix via in situ copolymerization to produce a new PMMA based copolymer (PMMA/DOPO‐AA). From UV–vis spectra, microscale combustion calorimeter (MCC) and thermogravimetric analyses (TGA) results, the as‐fabricated PMMA/DOPO‐AA copolymers not only keep relatively high transparency, but also exhibit remarkable improvements in the flame retardancy and thermal stability, such as increased T_0.5 by 60.2°C and limited oxygen index (LOI) by 4.1, and decreased peak heat released rate (PHRR) by 34.7%. Thermal degradation behaviors investigated by real time Fourier transform infrared spectra (RTIR), char structure analysis studied by scanning electron microscope (SEM) and pyrolysis gaseous products studied by TGA coupled with FTIR (TGA‐FTIR) demonstrate that the catalytic charring function of DOPO‐AA in condensed phase and DOPO flame retardant systems in the gas phase are two key factors for the property enhancements. This work not only provides a promising flame‐retardant monomer for polymers, but also will stimulate more efforts on the development of DOPO‐containing flame‐retardant monomers. Copyright © 2015 John Wiley & Sons, Ltd.