The efficiency of the second-order nonlinear least squares estimator and its extension

We revisit the second-order nonlinear least square estimator proposed in Wang and Leblanc (Anne Inst Stat Math 60:883–900, 2008) and show that the estimator reaches the asymptotic optimality concerning the estimation variability. Using a fully semiparametric approach, we further modify and extend the method to the heteroscedastic error models and propose a semiparametric efficient estimator in this more general setting. Numerical results are provided to support the results and illustrate the finite sample performance of the proposed estimator.     

Crystal structures and magnetism of infinite alternating chains arranged by paddle-wheel dinuclear copper and mononuclear copper units

The crystal structures and magnetic properties of two novel polyclusters {[Cu(3)(tci)(2)(H(2)O)(2)]·12H(2)O}(n) (1) and {[Cu(3)(tci)(2)(H(2)O)(2)]·6H(2)O}(n) (2) (tci = tris(2-carboxyethyl) isocyanurate) are investigated. The X-ray crystallographic analysis reveals that they contain interesting infinite alternating chains of dinuclear paddle-wheel copper and mononuclear copper units arranged in ABBA magnetism exchange mode. Variable-temperature magnetic susceptibility measurements on the two polyclusters show strong antiferromagnetism couplings between copper ions with exchange interactions J = -181.4 cm(-1), zj' = -0.31 cm(-1) for 1, J = -170 cm(-1), zj' = -0.42 cm(-1) for 2. With the aim of studying magneto-structural correlation, we synthesized a three-dimensional polymer [Cu(3)(tci)(2)(py)(4)(H(2)O)(2)](n) (3) based on isolated dinuclear cluster and mononuclear copper units. Fitting the susceptibility data yielded J = -176.1 cm(-1), zj' = -0.084 cm(-1) for 3.     

Ag@AgCl修饰的锐钛矿相TiO2纳米管的制备及其光催化性能

首先采用水热合成法和双氧水处理制备了具有锐钛矿相的TiO2纳米管,然后通过沉淀和光化学反应将Ag@AgCl纳米粒子负载于其上,从而制得TiO2纳米管负载的表面等离子体光催化剂.结果表明,经Ag@AgCl纳米粒子修饰后,锐钛矿相TiO2纳米管因表面等离子共振效应而对可见光具有明显的响应,光生电子-空穴对更容易分离,因而T...     

Synthesis and characterization of novel vanadium dioxide nanorods

Novel vanadium dioxide nanorods were fabricated via a surfactant-assisted hydrothermal method at 180 °C for 48 h in the presence of cetyltrimethylammonium bromide (CTAB). The self-assembled samples were characterized by XRD, SEM, TEM, HRTEM and FT-IR. The results show that the products are nanorods, which are pure B phase vanadium dioxide with high crystallinity. The obtained nanorods have diameters of 40-60 nm with lengths up to 1-2 um. The probable formation mechanism of vanadium dioxide is also discussed.     

A new luminescent metal-organic framework for selective sensing of nitroaromatic explosives

A microporous luminescent metal-organic framework [Zn_4L_2(H_2O)_2].(H_2O)_m(DMA)_n(1)(H_4L=5,5'-((1H-pyrazole-3,5-dicarbonyl)bis(azanediyl))diisophthalic acid, DMA=N,N-dimethylacetamide) was synthesized and characterized by infrared radiation(IR), thermogravimetric analyses(TGA), powder X-ray diffraction spectra(PXRD) and X-ray diffraction. Complex 1has a three dimensional(3D) framework, which can be simplified as 5,5,5,5-c net with the Schlfi symbol of {43.64.83}{44.65.8}{45.65}2. This luminescent metal-organic framework(MOF) shows selectively sensitive to nitrobenzene and series of nitroaromatic explosives such as 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene, and exhibits well recyclability. So complex 1 could be used to detect nitroaromatic explosives as a selective sensing material.     

急性铅中毒误诊26例报告

饮用含铅锡酿酒器酿造的酒,可引起急性铅中毒,多系统损害,临床表现没有特异性,易误诊为其他疾病,误诊率高,应引起临床高度重视。     

Semiparametric efficient estimators in heteroscedastic error models

In the mean regression context, this study considers several frequently encountered heteroscedastic error models where the regression mean and variance functions are specified up to certain parameters. An important point we note through a series of analyses is that different assumptions on standardized regression errors yield quite different efficiency bounds for the corresponding estimators. Consequently, all aspects of the assumptions need to be specifically taken into account in constructing their corresponding efficient estimators. This study clarifies the relation between the regression error assumptions and their, respectively, efficiency bounds under the general regression framework with heteroscedastic errors. Our simulation results support our findings; we carry out a real data analysis using the proposed methods where the Cobb–Douglas cost model is the regression mean.

     

猪胸腺素对带瘤小鼠胸腺细胞及其富含PNA一和PNA+细胞淋转反应的研究

本文报道用'H-TdR掺入法测定小鼠胸腺细胞及其亚群在有丝分裂原作用下的淋转反应，以及猪胸腹素对带瘤机体免疫功能的影响.实验结果丧明，带瘤小鼠胸腺细胞的淋转反应随着殉龄的增长而逐渐降低.在体外用猪胸腺素与胸腺细胞一起温育，淋转反应有不同程度提高，如先给小鼠腹腔注射猪胸腺素则淋转反应的效果更为显著，说明猪胸腺素对带瘤机体的免疫功能具有积极的ifa'节作用.