Time dependent analysis of finite buffer fluid flows and risk models with a dividend barrier

Based on the matrix-analytic approach to fluid flows initiated by Ramaswami, we develop an efficient time dependent analysis for a general Markov modulated fluid flow model with a finite buffer and an arbitrary initial fluid level at time 0. We also apply this to an insurance risk model with a dividend barrier and a general Markovian arrival process of claims with possible dependencies in successive inter-claim intervals and in claim sizes. We demonstrate the implementability and accuracy of our algorithms through a set of numerical examples that could also serve as test cases for comparing other solution approaches.      

Voltage ‐ Current Study of an Atmospheric Dielectric Barrier Discharge

The discharge behaviour of an atmospheric dielectric barrier parallel plate discharge, used for surface treatment, is studied. Since an uniform plasma is preferable for surface treatment, filaments must be avoided in the discharge. The occurrence of filaments can be detected by measuring the current flowing through the discharge. Current and voltage measurements give an indication of the power consumption by the plasma. The power consumption of the plasma as function of the applied frequency is examined. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The design of molecules containing planar tetracoordinate carbon

A novel preference for planar tetracoordination was observed over the conventional tetrahedral arrangement in a new series of C₅H₂, C₅H₄, C₅H₄^1+/2+ and related compounds. The stability of these molecules is assessed with the ring-opening barriers, HOMO-LUMO gap, singlet-triplet energy differences and nucleus independent chemical shift values.     

Preparation and properties of isobutylene–isoprene rubber–clay nanocomposites

Isobutylene isoprene rubber (IIR)‐clay nanocomposites have been prepared successfully by melt intercalation with maleic anhydride‐grafted IIR (Ma‐g‐IIR) and organophilic clay. In IIR‐clay nanocomposites, the silicate layers of the clay were exfoliated and dispersed into the monolayer. The nanocomposites exhibited greater gas barrier properties compared with those of Ma‐g‐IIR. When 15 phr clay was added, gas barrier properties were 2.5 times greater than those of Ma‐g‐IIR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1182–1188, 2006     

Electrical properties of polypyrrole/p‐InP structure

The polypyrrole/p‐InP structure has been fabricated by the electrochemical polymerization of the organic polypyrrole onto the p‐InP substrate. The current–voltage (I–V), capacitance–voltage (C–V), and capacitance–frequency (C–f) characteristics of the PPy/p‐InP structure have been determined at room temperature. The structure showed nonideal I–V behavior with the ideality factor and the barrier height 1.48 and 0.69 eV respectively. C–f measurements of the structure have been carried out using the Schottky capacitance spectroscopy technique and it has been seen that there is a good agreement between the experimental and theoretical values. Also, it has been seen that capacitance almost show a plateau up to a certain value of frequency, after which, the capacitance decreases. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the p‐InP that can follow the a.c. signal. The interface state density N_ss and relaxation time τ of the structure were determined from C–f characteristics. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1572–1579, 2006     

石墨炉原子吸收光谱法直接测定血样中硒

用石墨炉原子吸收光谱法，以硝酸铜和硝酸铵为基体改进剂，塞曼效应扣背景，采用标准加入法可直接测定血样中硒，回收率为95％～105％，相对标准偏差为5．8％，检出限为96pg，测定结果准确可靠。     

Multilayered Cu–Ti deposition on silicon substrates for chemiresistor applications

Abstract

On the perspective to develop CuO–TiO₂ MOS, multilayered Cu and Ti thin layers were alternatively deposited on silicon wafers using 25?keV Ar?+?ion beam sputtering and, subsequently, oxidized by thermal annealing in air at 400?°C for 24?h. The deposited films have variable ratios of the Cu and Ti % at. One of the main goal is to obtain such multilayers avoiding the presence of Cu–Ti–O compounds. The samples were characterized in terms of composition (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations). In particular, SIMS maps allows to observe the spatial distribution and thickness of each phase of the Cu/Ti multilayers, and further to observe Cu diffusion and mixing with Ti, as well as phase separation of CuO and TiO₂ in the samples. The reasons of this effect represent an open issue that has to investigated, in order to improve the MOS fabrication.     

Determination of acetone, hexanal and heptanal in blood samples by derivatization with pentafluorobenzyl hydroxylamine followed by headspace single-drop microextraction and gas chromatography–mass spectrometry

In the study, we developed a simple, rapid, sensitive, and inexpensive method for determination of the disease biomarkers of acetone, hexanal and heptanal in human blood. For the first time, derivatization of carbonyls with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine (PFBHA) was combined with headspace single-drop microextractin (HS-SDME) and gas chromatography-mass spectrometry (GC–MS) and applied to the analysis of acetone, hexanal, and heptanal in human blood. At first, acetone, hexanal and heptanal in blood were derivatized with PFBHA and formed oximes in several seconds. Sequentially, the oximes were headspace extracted and concentrated by a microdrop solvent. Finally, the extracted oximes were analyzed by GC–MS. HS-SDME conditions and method validations were studied. Due to needing of only 2 μl organic solvent, short extraction time of 8 min, and simple operation, derivatization-HS-SDME was shown to be a rapid, simple, and inexpensive technique for analysis of acetone, hexanal, and heptanal in human blood. Moreover, it had low detection limit values from 0.24 to 0.62 nM, and good reproducibility (R.S.D. less than 12%).     

小儿佝偻病血中微量元素的观察

对７１例确诊为不同阶段的佝偻病患儿同时进行观察血液中微量元素锌、铜、铅以及血清钙、磷、碱性磷酸酶的变化。结果表明，佝偻病组的血铸、血钙、血磷均低于正常组，血铅、ＡＫＰ高于正常组，血铜则两组无大差异，但铜／锌比值正常组为０．２２±０．６３明显低于佝偻病组０．３６±０．５５，ｔ＝３．２０，Ｐ＜０．０５．各期佝偻病微量元素的变化与正常儿对比，在佝偻病的初期血磷略低于正常，血锌明显减少，碱性磷酸酶升高。在疾病的激期钙、磷、锌明显低于正常，碱性磷酸酶及铅升高，恢复期各元素基本恢复正常。     

π-Bindungsbeitrag in Boranen, 2. Mitt.:Ab initio- und Kraftfeld-Rechnungen von Vinyldifluorboran

Ab initio calculations on vinyldifluoroborane yield a -contribution of 23 kJ/mol (5.5 kcal/mol) mainly due to the C=C bond and not to the lone pairs of the fluorine atoms. The rotational barrier was also determined. The force field calculations favour the interpretation of the bond structure derived from the theab initio results.