子空间迭代法计算振型导数

本文采用子空间迭代法在计算结构频率和振型的同时计算振型导数．     

[Zn(AZT)4(H2O)2](PA)2∙4H2O和[Zn(AZT)2(H2O)4](HTNR)2∙4H2O (AZT = 3-叠氮-1,2,4-三唑, HPA = 苦味酸, H2TNR = 斯蒂芬酸)的合成、晶体结构、热分解及感度性能

以3-叠氮-1,2,4-三唑为配体，PA–（苦味酸根）或HTNR–（2,4,6-三硝基间苯二酚脱去一个羟基的质子后形成的离子）为外阴离子，制备得到了两种新的配合物：[Zn(AZT)4(H2O)2](PA)2∙4H2O和[Zn(AZT)2(H2O)4](HTNR)2∙4H2O。[Zn(AZT)4(H2O)2](PA)2∙ 4H2O的X射线晶体数据表明，中心Zn2+离子与来自4个AZT分子的N原子和2个H2O分子的O原子配位；而对于[Zn(AZT)2(H2O)4](HTNR)2∙4H2O来说，6个配位原子来自2个AZT分子的N原子和4个H2O分子的O原子。在两种配合物中，AZT配体分子的配位点都是三唑环上的4位N原子。H2O分子对于分子间氢键的形成起到了重要的作用，在分子间氢键的作用下形成了配合物的晶体结构。在[Zn(AZT)4(H2O)2](PA)2∙4H2O的晶体结构中，还存在错位面对面π-π堆积作用，它对于晶体结构的形成和稳定性也起到了重要作用。TG-DTG和DSC分析结果显示，[Zn(AZT)2(H2O)4](HTNR)2∙4H2O的热分解过程不如[Zn(AZT)4(H2O)2](PA)2∙4H2O剧烈，原因在于前者分子中含有较多配位水分子和较少AZT配体分子。感度测试结果表明，[Zn(AZT)4(H2O)2](PA)2∙4H2O有一定的火焰感度，而[Zn(AZT)2(H2O)4](HTNR)2∙4H2O却对热不敏感；两种化合物在撞击和摩擦作用下都表现钝感。     

2×2矩阵的平方根

在线性代数中我们能够用适当的公式计算矩阵的逆,特征值,特征向量。这篇短文的目的是给出一个2×2矩阵平方根的简单公式。作为卡莱——哈密顿定理的一个应用。     

覆面层对玻璃棉吸声性能的影响

本文通过试验探讨了四种覆面怪对玻璃板吸声性能的影响，结果表明：在不同频率范围，铝箔及穿孔铝穆面层对的吸声性能影响较大，而玻纤毡和橡胶面层的影响较小。     

EXTRACTION CHEMISTRY OF RARE EARTHS BY MONO-ALKYL ISOPROPYLPHOSPHONATES

The influence of chemical structure of ester alkyl group of mono-alkyl isopropylphosphonates on the extraction behaviours of rare earth has been studied. The mono-alkyl isopropylphosphonate bearing β-substituted ester alkyl group shows high K_(ex) value, which is evidently depressed, usually in two orders of magnitude, by introducing a branch chain on the α-position of the ester alkyl group. The steric effect of ligand is usually enhanced due to the characteristic lanthanide contraction.z2The extraction chemistry of rare earths by mono-amylnonyl isopropylphosphonates (MANPP) was studied in detail The thermodynamic function was estimated and the "tetrad effect" between K_(ex) value or △G value and atomic number was observed. In addition, the composition and structure of the coordinated compound was studied. As demonstrated by the experimental data, the extractive separation of Sm and Nd by MANPP in chloride solution was better than that in nitrate system.     

超高效液相色谱法-电化学检测器同时测定大血藤中8种化学成分的含量北大核心CSCD

提出了超高效液相色谱法-电化学检测器(UHPLC-ECD)同时测定大血藤样品中羟基酪醇、原儿茶酸、红景天苷、酪醇、儿茶素、隐绿原酸、绿原酸、表儿茶素含量的方法。称取大血藤样品粉末约1 g,过0.42 mm筛,用30 mL 30%(体积分数)甲醇溶液超声提取10 min,离心,提取液经0.22μm滤膜过滤后进样分析。以Waters ACQUITY UPLC BEH Shield RP18色谱柱为固定相,以不同体积比的乙腈-50 mmol·L^(-1)柠檬酸盐缓冲液(pH 2.76)为流动相进行梯度洗脱;设置ECD库仑检测池的第一通道检测电压为350 mV(用于检测羟基酪醇、原儿茶酸、儿茶素、隐绿原酸、绿原酸、表儿茶素),第二通道检测电压为600 mV(用于检测红景天苷、酪醇)。结果显示:8种化学成分的质量浓度在一定范围内与其对应的峰面积呈线性关系,检出限(3S/N)为0.7~8.5μg·L^(-1);对混合标准溶液或样品溶液进行精密度(n=6)、稳定性(n=7)试验,各目标物峰面积的相对标准偏差均小于5.0%;对实际样品进行加标回收试验,回收率为96.0%~102%。方法用于不同产地的24批大血藤样品分析,其中S15和S18样品中红景天苷和绿原酸均不符合要求。     

Optical Image Contrast Reversal Using Bacteriorhodopsin Films

The implementation of image contrast reversal by using a photochromic material of Bacteriorhodopsin (BR) films is demonstrated with two methods based on the optical properties of BR. One is based on the absorption difference between the B and M states. Images recorded by green light can be contrast reversed readout by violet light. The other is based on the photoinduced anisotropy of BR when it is excited by linear polarization light. By placing the BR film between two crossed polarizers (i.e. a polarizer and an analyser), the difference of polarization states of the recorded area and the unrecorded area can be detected, and thus different contrast images can be obtained by rotating the polarization axis of the analyser.     

Delay Effect on Coherent Transfer of Optical Frequency Based on a Triple-Pass Scheme

We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay and servo delay. The delay effect confines the servo bandwidth within 1/8 and induces a residual fiber phase noise after noise compensation. For a 25-km-long fiber, the servo bandwidth is found to be around 1 k Hz, and the fiber phase noise is suppressed approaching to the theoretical limitation. The triple-pass scheme enables the simultaneous transfer of optical frequency to multiple remote users. The performance of noise compensator in the triple-pass scheme can achieve a similar level result compared with that in the double-pass scheme.     

基于UV-Vis吸收光谱的活性大红BES的光催化降解BPNN模拟研究

以对Plackett-Burman设计实验结果筛选确定的TiO₂用量、溶液初始浓度ｃ₀、光照射时间t、溶液初始pH值4个因素为自变量,脱色率为因变量,采用BP神经网络基于Box-Behnken设计和U₁₀(10×52×2)设计实验数据建模,对活性大红BES溶液进行光催化降解模拟研究。降解过程中BES溶液的脱色率通过紫外-可见分光光度法测定后计算获得。建立的BPNN模型对训练集和预测集计算结果相关系数r分别为0.996 4和0.963 6,脱色率实验值与预测值的平均相对误差MRE分别为6.14%和7.76%。将该模型用于分析各因素对BES光催化降解的影响,表明初始浓度较低时,pH 5.0和适当的c_TiO2条件下有利于提高BES的降解率。根据该模型分析得出ｃ₀为40 mg·L-1时的优化实验条件为pH 5.0,c_TiO2=1.20 g·L-1,t=35 min,该条件下BES脱色率的模型计算值为99.16%。经实验验证获得的脱色率为98.20%,脱色率计算值与实验值十分接近,相对误差仅为-0.96%。