带插值条件的拟线性最小二乘估计

提出了带插值点的拟线性最小二乘法,并给出了带插值点的拟线性最小二乘法拟合的最小二乘估计,证明了及其参数具有无偏性。     

OPTIMAL INTERIOR PARTIAL REGULARITY FOR NONLINEAR ELLIPTIC SYSTEMS WITH DINI CONTINUOUS COEFFICIENTS

In this article,we consider nonlinear elliptic systems of divergence type with Dini continuous coefficients.The authors use a new method introduced by Duzaar and Grotowski,to prove partial regularity for weak solutions,based on a generalization of the technique of harmonic approximation and directly establish the optimal Ho¨lder exponent for the derivative of a weak solution on its regular set.     

Atom-by-atom fabrication of metal clusters for efficient selective hydrogenation

Supported metal catalysts,in which the metal is usually finely dispersed into nanoparticles(NPs)in size of a few nanometers on high-surface-area materials,are the workhorses in heterogeneous catalysis and have been extensively used in various key industrial processes[1].However,the surface heterogeneity arising from the uneven size distribution as well as the lower atomic efficiency derived from the presence of unexposed interior atoms of metal NPs often leads to inferior activity/selectivity.     

Dispersion filter for spectral and spatial resolution of pure rotational Raman scattering

A new filtering technique for Raman spectroscopy utilizes atomic vapor to suppress strong elastic and Rayleigh scattering while simultaneously resolving individual rotational Raman lines. Filtered images capture high-resolution spectral information in one dimension and spatial resolution in the other dimension. The filter is based on resonance enhanced dispersion, where the index of refraction varies dramatically. In a simple prism geometry the vapor disperses incident radiation according to frequency. A mercury-vapor-based dispersion filter has been fabricated, modeled, and demonstrated to capture pure rotational Raman scattering from CO(2).     

Effects of NaCl on the J-aggregation of two thiacarbocyanine dyes in aqueous solutions

The effects of NaCl on the aggregation of two typical thiacarbocyanine dyes (3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-phenyl-thiacarbocyanine triethyl ammonium salt (Dye 1) and 3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-methyl-thiacarbocyanine triethyl ammonium salt (Dye 2)) in aqueous solution have been studied by using absorption spectroscopy, fluorescence spectroscopy, and 1H- and 23Na-NMR measurements. It is found that the J-aggregation of two dyes can be promoted by the addition of NaCl and that the effective coherence length of the J-aggregate is shorter than that obtained without NaCl. Fluorescence spectra demonstrate that the fluorescence intensities of the J-aggregates of two dyes are quenched by addition of NaCl. This is consistent with the decrease of the effective coherence length of J-aggregates of the two dyes in the presence of NaCl. 1H-NMR spectra of two dyes show that the Na(+) ions penetrate into the J-aggregates and replace the counterion (triethylammonium ions) in two dyes. The measurements of the chemical shifts of 23Na nuclei provide further information about the interaction between the Na(+) ions and dye anions in the J-aggregates of the two dyes. Due to this interaction, the electrostatic repulsion between the dye anions in the J-aggregates can be reduced and thus accelerate the aggregation of the two dyes in the presence of NaCl. The apparent association constants between Na(+) ions and dye molecules in J-aggregates of Dye 1 and Dye 2 estimated from the measured chemical shifts of 23Na nuclei are about 2.38 M(-1) and 1.35 M(-1), respectively.     

Tuning the CD spectrum and optical rotation value of a new binaphthalene molecule with two spiropyran units: mimicking the function of a molecular "AND" logic gate and a new chiral molecular switch

With the view to developing new chiral molecular switches and logic gates, a new binaphthalene molecule with two spiropyran units (1) was synthesized and characterized. Absorption and 1H NMR spectral studies of 1 after reaction with acid/base indicate acidichromism can occur to compound 1. The synergistic actions of acid and UV light irradiation result in a remarkable change for the CD spectrum of the relatively dilute solution of 1, mimicking the behavior of a chiral "AND" gate, since the "ouput" is the CD signal. Furthermore, the optical rotation value of the relatively concentrated solution of 1 can be reversibly tuned after sequential reactions with acid and base, and thus a chiral molecular switch with nondestructive "output" signal is realized. The present results not only add a new example of chiral molecular switch with nondestructive readout but also provide a chiral "AND" gate based on the axial chiral binaphthalene to which switchable units are linked.     

基于高速摄影视觉测量的静爆破片运动参数测试方法

为提高静爆试验中破片初速和速度衰减系数解算的可信度,提出了基于高速摄影视觉测量的静爆破片运动参数测试方法,该方法主要包括高速摄像机数据采集、视觉测量解算破片轨迹、基于运动模型拟合求解三个步骤。试验证明,该方法能够准确获取各破片的初速和速度衰减系数,可信度高,是一种有效的静爆试验破片运动参数测试方法。     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

部分水解聚丙烯酰胺柠檬酸铝体系临界交联浓度的研究

采用落球粘度计、核孔膜过滤、动态光散射 (DLS)和2 7Al NMR法 ,研究了高分子量、低浓度的部分水解聚丙烯酰胺 (HPAM)与柠檬酸铝 (AlCit)体系形成交联聚合物溶液 (LPS)的临界交联浓度 .研究结果表明 ,HPAM AlCit体系在聚合物浓度较低时 ,溶液中主要发生形成交联聚合物线团 (LPC)的交联反应 ,此时形成的是LPS ,聚合物浓度增加到某一临界值后 ,体系中形成线团后 ,存在线团间的交联 ,此时形成的是弱凝胶 .不同方法所测得的HPAM AlCit体系的临界交联浓度基本相同 ,对于粘均相对分子质量为 1 4× 10 7的HPAM ,在NaCl浓度为 2 0 0 0mg L ,交联比 2 0∶1时形成的交联体系 ,其临界交联浓度在 2 0 0～ 30 0mg L间 .     

Developing an Iridium Oxide Film Modified Microelectrode for Microscale Measurement of pH

Iridium oxide film modified microelectrode was fabricated by anodic oxidation method onto the tip of an etched iridium wire in diluted sulfuric acid solution by cyclic voltammetry. The iridium oxide film microelectrode exhibited very promising pH sensing performance, with an ideal Nernstian in the tested pH range of 0 to 14. This method for preparing microelectrode allowed accurately control of the deposited amount and the rate of the iridium oxide film growth. The electrodes demonstrated advantages of long lifetime, good selectivity and fast response with a relative time less than 0.2 s for pH changes in a large scale. The microelectrode was not interfered by a wide variety of inorganic ions and organic compounds. Furthermore, the electrodes were successfully applied to the measurement of pH in microscale of apples.