超级微波消解-电感耦合等离子体发射光谱（ICP-OES）法测定土壤中18种元素

为提高土壤多元素同时检测的效率,采用超级微波消解-电感耦合等离子体发射光谱法测定土壤中钾、钠、钙、镁、铜、铁、锰、锌、磷、硫、硼、砷、镉、铬、铅、钴、镓、锂等18种元素含量。比较了超级微波消解、常规微波消解和电热板消解的处理效果,采用超级微波消解法对样品进行前处理,并优化了消解条件。在最优条件下,各元素的检出限在0.05~20 mg/kg,加标回收率在86.2%~107.5%,RSD在0.1%~3.0%,方法准确度及精密度可以满足多元素同时测定的需求,且该方法具有简单、快速、成本低、用酸量少、重现性好等特点。     

Simulation of variations in mechanical properties of polyurethane elastomers modified with carbon nanotubes

The addition of extremely small portions of single-wall carbon nanotubes causes an anomalous change in mechanical properties of a cross-linked polyurethane-amide-urea elastomer containing 10% of polyamide-6; namely, with a nanofiller content of hundredths and thousandths of a percent, local maxima of elastic modulus and ultimate stress are observed. In the work, the anomalous variation in the elastic modulus is simulated relying on the concept of intermediate phase layer formation at the boundary of contacting particles of the initial material.     

二分图中关于Enomoto问题的结果

设k,n1和n2是3个正整数,G=（V1,V2;E）是一个二分图,使得｜V1｜=n1,｜V2｜=n2,其中n1≥2k＋1,n2≥2k＋1并且n1-n2≤1．如果对任意不相邻的x∈V1和y∈V2,都有d（x）＋d（y）≥2k＋2,则G包含k个相互独立的圈．以上结果部分地回答了Enomoto提出的关于二分图有独立圈的问题．     

利用四氯乙烷胺化反应合成联氢化嘧啶衍生物的研究

利用均四氯乙及二氯甲烷的胺化反应,合成了联氢化嘧啶衍生物1～5,4a,8b-反-4,5,8a,9a-四氮杂全氢芴(6)和8b,8c-顺-3a,4a,7a,8a-四氮杂环戊并全氢芴(7)。化合物(6)和(7)的顺反异构体在酸催化下开环,异构生成较稳定的6b和7a。     

氢链系统中的非线性问题

考虑氢原子之间的非谐相互作用,分别用代数方法和变分法求得氢链系统中扭结与反扭结孤波解,解的特点是在非谐项的影响下,正孤波与反孤波不再对称,从而解释了实验中观察到的冰分子中L缺陷和D缺陷的对称性破缺现象,进一步的计算表明,由于非谐项的存在,正孤波与反孤波携带的能量也失去对称性,且代数方法和变分法给出一致的结果.     

三阶泛函微分方程的周期解的存在性

本文利用重合度理论研究了一类三阶泛函微分方程方程的2π-周期解的问题,获得了该方程存在2π-周期解的若干新结论,改进推广了有关文献中的已有结果．     

Intermolecular interaction in an open-shell pi-bound cationic complex: IR spectrum and coupled cluster calculations for C2H2+-Ar

The intermolecular potential energy surface (PES) of Ar interacting with the acetylene cation in its (2)Pi(u) ground electronic state is characterized by infrared photodissociation (IRPD) spectroscopy and quantum chemical calculations. In agreement with the theoretical predictions, the rovibrational analysis of the IRPD spectrum of C(2)H(2) (+)-Ar recorded in the vicinity of the antisymmetric CH stretching fundamental (nu(3)) is consistent with a vibrationally averaged T-shaped structure and a ground-state center-of-mass separation of R(c.m.) = 2.86 +/- 0.09 A. The nu(3) band experiences a blueshift of 16.7 cm(-1) upon complexation, indicating that vibrational excitation slightly reduces the interaction strength. The two-dimensional intermolecular PES of C(2)H(2) (+)-Ar, obtained from coupled cluster calculations with a large basis set, features strong angular-radial coupling and supports in addition to a global pi-bound minimum also two shallow side wells with linear H-bound geometries. Bound state rovibrational energy level calculations are carried out for rotational angular momentum J = 0-10 (both parities) employing a discrete variable representation-distributed Gaussian basis method. Effective spectroscopic constants are determined for the vibrational ground state by fitting the calculated rotational energies to the standard Watson A-type Hamiltonian for a slightly asymmetric prolate top.     

基于联合变换相关器的像移测量仿真分析

对基于联合变换相关器的像移测量数学原理进行了说明,介绍了面阵CCD的安装位置以及输入图像的获取方法,分析了低信噪比输入图像、相对转动位移对测量精度的影响。应用MATLAB对输入图像进行傅里叶变换得到联合功率谱,对二值化处理的功率谱进行傅里叶变换得到相关输出,用质量中心算法计算出像移量。分析得出,输入图像信噪比大于5dB,测量均方误差小于0.05像素;输入图像相对转动位移在0.1°的范围内,转动位移对测量精度和峰噪比的影响可以忽略不计。综合分析表明像移测量均方误差小于0.05像素。     

Effect of Radiation from an Infrared Laser and <Emphasis Type="Italic">γ</Emphasis>-Rays from <Superscript>60</Superscript>Co on the Molecular–Topological Structure of Polyvinylidene Fluoride

We investigate the molecular–topological structure of polyvinylidene fluoride (PVDF) irradiated with γ-rays from ⁶⁰Co and IR radiation from a carbon dioxide laser by the thermomechanical spectroscopy method. The initial PVDF has a topological three-block network structure containing the low- and high-temperature amorphous blocks and crystalline fragments. Both types of irradiation can initiate interblock mass transfer of the macromolecular fragments from the amorphous to the crystalline form. As a result, unlike the predominantly amorphous structure of the native polymer, which is 7% crystalline, the weight fraction of the crystalline modification of the PVDF due to irradiation by an IR laser increases to 72%. Comparative analysis leads to the conclusion that the PVDF has a greater resistance to γ-irradiation than to IR laser irradiation. After IR laser irradiation, the pseudo-network structure of PVDF undergoes noticeable changes. The quantitative content of the crystalline fragments of macromolecules increases by almost an order of magnitude; the mobility of chains is reduced, and the rigidity of the chains is increased. However, the molecular flow of the polymer irradiated by the laser and γ-rays begins in the same temperature range (437 – 441 K) near where the native polymer is flowing (438 K).