Differentiation and dating of red ink entries of seals on documents by HPLC and GC/MS

A novel approach for differentiation and dating of red ink entries of seals on documents was developed based on ion‐pairing HPLC (IP‐HPLC) and GC/MS. Sixty‐nine red ink pastes of seals were collected and the chromatographic conditions for separation of the dye components by IP‐HPLC and the volatile additives by GC/MS in the ink entries were optimized. According to the dye components and additives, the ink entries were classified by HPLC with a multi‐wavelength UV detector. The volatile components of the inks were identified by GC/MS and the classification of the ink entries was also investigated based on these volatile additives. The results showed that most of the ink entries of the seals can be differentiated by combining HPLC with a multi‐wavelength detector and GC/MS methods. The degradation of the standard dye mixtures and the compositional changes of the ink entries of seals were investigated in light or natural aging conditions. The results indicated that the dye components decomposed in light or natural storage conditions, while the rates of the degradation depended on the structures of the dye components, the aging conditions, even the additives of the ink pastes. The results also showed that there existed good relationships between the compositional changes of the ink entries and the aging time, which can provide scientific evidences and valuable clues for dating of the ink entries.     

The preparation and structural characterization of ambient-dried porous methylsilicone matrix doped with SiO2 powder

Porous methylsilicone monoliths doped with SiO₂ powder were prepared by dispersion of SiO₂ nanoparticles in methylsilicone oligomer solution followed by ammonia-catalyzed gelation and ambient drying. The microstructure of the porous composite monoliths was investigated by FTIR, SEM, and N₂ adsorption. The results indicated that SiO₂ evenly dispersed in methylsilicone matrix. The thermal stability of SiO₂-doped methylsilicone monoliths had been enhanced. The structure stability and hydrophobic property of the composite monoliths were maintained until 400 °C.     

导向相应功率定位中时延不确定项的影响

在分布式传声器网络应用中,可控波束形成器导向相应功率(SRP)声源定位算法受到导向时延不准确的影响导致定位不稳定.将导向时延不确定项引入SRP定位模型,并对引起不确定项的主要干扰因素进行了分析建模,同时提出了应对导向时延不确定项的SRP定位算法.蒙特卡罗仿真和分析表明该算法具有抑制噪声和降低定位误差的效果,实际实验数据...     

Efficient estimation for semiparametric varying- coefficient partially linear regression models with current status data

This article considers a semiparametric varying-coefficient partially linear regression model with current status data. The semiparametric varying-coefficient partially linear regression model which is a generalization of the partially linear regression model and varying-coefficient regression model that allows one to explore the possibly nonlinear effect of a certain covariate on the response variable. A Sieve maximum likelihood estimation method is proposed and the asymptotic properties of the proposed estimators are discussed. Under some mild conditions, the estimators are shown to be strongly consistent. The convergence rate of the estimator for the unknown smooth function is obtained and the estimator for the unknown parameter is shown to be asymptotically efficient and normally distributed. Simulation studies are conducted to examine the small-sample properties of the proposed estimates and a real dataset is used to illustrate our approach.     

OPTIMAL CONVERGENCE RATES OF LANDAU EQUATION WITH EXTERNAL FORCING IN THE WHOLE SPACE

In this paper, we combine the method of constructing the compensating function introduced by Kawashima and the standard energy method for the study on the Landau equation with external forcing. Both the global existence of solutions near the time asymptotic states which are local Maxwellians and the optimal convergence rates are obtained. The method used here has its own advantage for this kind of studies because it does not involve the spectrum analysis of the corresponding linearized operator.     

TOBIT模型在医疗费用研究中的应用

对一般人群进行医疗费用调查研究时,会存在有相当一部分人的医疗费用支出为零,以此作为因变量使用经典的线性回归进行统计建模时将会导致估计值的偏差。本文尝试使用Tobit模型及其半参数估计方法解决因变量存在大量零删失数据的问题,通过对太原市城镇居民医疗费用相关影响因素调查数据的实证分析,用以为医疗费用控制和医疗保险制度改革提供更有效的统计学方法支持和政策依据。     

Smoothing Newton-Like Method for the Solution of Nonlinear Systems of Equalities and Inequalities

In this paper, we present a smoothing Newton-like method for solving non-linear systems of equalities and inequalities. By using the so-called max function, we transfer the inequalities into a system of semismooth equalities. Then a smoothing Newton-like method is proposed for solving the reformulated system, which only needs to solve one system of linear equations and to perform one line search at each iteration. The global and local quadratic convergence are studied under appropriate assumptions. Numerical examples show that the new approach is effective.     

A construction of fully diverse unitary space-time codes

Fully diverse unitary space-time codes are useful in multiantenna communications, especially in multiantenna differential modulation. Recently, two constructions of parametric fully diverse unitary space-time codes for three antennas system have been introduced. We propose a new construction method based on the constructions. In the present paper, fully diverse codes for systems of odd prime number antennas are obtained from this construction. Space-time codes from present construction are found to have bet...     

Symmetric and unsymmetric "dumbbells" of Ru2-alkynyl units via C-C bond formation reactions

Oxidative homocoupling (Glaser) reaction of Ru2 compounds bearing peripheral ethyne resulted in symmetric dimers. Cross-coupling (Sonogashira) reaction between Ru2 compounds bearing peripheral iodo and ethyne groups yielded an unsymmetric dimer. Voltammetric data indicated that Ru2 units in the symmetric dimers are noninteracting, and the unsymmetric dimer is best described as a weakly coupled push-pull compound.     

RNA-mediated synthesis of palladium nanoparticles on Au surfaces

RNA catalysts for the shape-controlled synthesis of Pd particles from the precursor complex trisdibenzylideneacetone dipalladium ([Pd2(DBA)3] were recently discovered in our laboratory (J. Am. Chem. Soc. 2005, 127, 17814-17818). In the work described here, RNA codes for hexagonal Pd platelets and Pd cubes were covalently immobilized on gold surfaces and evaluated for their activity toward particle synthesis. When coupled to gold via oligoethylene glycol linkers, both RNA sequences were able to catalyze the formation of Pd particles with the same shape control previously observed in solution. For low surface coverages, the average distance between RNA molecules on the surface was estimated at ca. 300 nm, yet large (e.g., dimensions of hundreds of nanometers) Pd hexagons and cubes still formed. This surprising result suggests that a single RNA molecule may be sufficient for nucleating and controlling the shapes of these particles. Finally, the use of surface-bound RNA as a tool for directing the orthogonal synthesis of materials on surfaces was demonstrated. Patterning the RNA code for Pd hexagons next to the code for Pd cubes, followed by incubation in a solution containing [Pd2(DBA)3], resulted in the spontaneous formation of spatially distinct spots of hexagonal and cubic particles.