Microstructure and protonic conductivity of H3PO4‐doped polyethylenimine–siloxane chemically covalently organic–inorganic hybrids

The chemically covalent polyethylenimine–siloxane hybrids doped with various amounts of ortho‐phosphoric acid (H₃PO₄) were prepared and characterized by FTIR, DSC, TGA, and solid‐state NMR spectra. The protonic conduction behavior of these materials was also investigated by means of impedance measurements. These observations indicate that the hydrogen bonding and protonic interactions exist between the dopant H₃PO₄ and the hybrid host, resulting in an increase in T _g of polyethylenimine segments. These hybrids are thermally stable up to 200 °C from TGA analysis. Conductivity studies show an Arrhenius behavior characteristic and the Grotthus‐like proton conduction, and a high conductivity of 10^?2–10^?3 S cm^?1 at 110 °C in dry atmosphere for the hybrid membrane with H₃PO₄/EI of 0.5. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2135–2144, 2006     

Synthesis,characterization, and properties of novel epoxy resins and cyanate esters

We synthesized a novel epoxy (dopotep) and cyanate ester (dopotcy) based on a phosphorus‐containing triphenol (dopotriol). The proposed structures were confirmed by IR, mass spectra, NMR spectra, and epoxy‐equivalent‐weight titration. The synthesized dopotep or dopotcy was copolymerized with diglycidyl ether of bisphenol A (DGEBA), 6′,6‐bis(3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazineyl)methane (F‐a), or dicyanate ester of bisphenol A (BADCY). Thus, copolymers based on DGEBA/dopotep/diphenylmethane (ddm), F‐a/dopotep, BADCY/dopotcy, and DGEBA/dopotcy were developed. The thermal properties, dielectric properties, and flame retardancy of these copolymers were investigated. The curing kinetics of dopotep/ddm and dopotep/diamino diphenylsulfone were studied with differential scanning calorimetry. The microstructure of DGEBA/dopotcy was studied with IR. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3487–3502, 2006     

Kinetic models for solution imidization of polyamic acid containing naphthalene‐pendant group

The kinetics and mechanisms of the solution imidization of polyamic acid resulting from a diamine, bis(4‐aminophenoxy‐3,5‐dimethylphenyl)naphthylmethane, and a dianhydride, 3,3′4,4′‐diphenylsulfonetetracarboxylic dianhydride, were studied at three various temperatures (145, 165, and 180 °C). The results were confirmed by means of ¹H NMR and gel permeation chromatography (GPC). Kinetic parameters were obtained by an isothermal study, and the results were quite close to second‐order kinetics for the homogeneous solution imidization. In addition, Carother's equation, Mark–Houwink theory, and GPC were used to explain the molecular weight of the imidization processes. The apparent activation energy (E_a) was 104 KJ/mol, and the pre‐exponential factor (k₀) was 3.48 × 10¹⁴. The proposed kinetic mechanism is in good agreement with the kinetic models. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4139–4151, 2001     

Effect of Cl~-ion on Anodic Iron Dissolution in H_2S-Containing Sulfuric Acid Solutions

ResearchershavestudiedtheeffectofCI-onthestructureandpropertiesofthecorrosionproductsinchloridesolutionscontainingH,S"'.IthasbeenfoundthattherearenocorrosioneffectsonironsurfaceswhicharesubmergedinconcentratedacidicchloridesolutionswithlowHZSlevel.Inthepast,theinteractionbetweentheCI-ionandFehasnotbeenstudiedcompletelyandintensively.TheanodicreactionofironinacidicsolutionscontainingHZSwastheironoxidationcatalyzedbyHS-3.WhenCI-ispresentinHZS-containingacidicsolutions,theeffectofCI-onir…     

The high level chopping phenomena of sink-in type triggered vacuumgaps

In the positive mode of the main gap with both triggering modes, it was found that the discharge is quite unstable. This instability has a strong influence on the precise control of the triggered vacuum gap (TVG) and gives rise to high transient voltage across the main gap. This unstable phenomenon is investigated in detail. The influence of triggering pulse type, residual pressure, contamination and main gap polarity on the chopping phenomena is described. The experimental setup is described, and results are discussed     

Analytic bounds and approximations for annuities and Asian options

Even in case of the Brownian motion as most natural rate of return model it appears too difficult to obtain analytic expressions for most risk measures of constant continuous annuities. In literature the so-called comonotonic approximations have been proposed but these still require the evaluation of integrals. In this paper we show that these integrals can sometimes be computed, and we obtain explicit approximations for some popular risk measures for annuities.Next, we show how these results can be used to obtain fully analytic expressions for lower and upper bounds for the price of a continuously sampled European-style Asian option with fixed exercise price. These analytic lower bound prices are as sharp as those from [Rogers, L.C.G., Shi, Z., 1995. The value of an Asian option. J. Appl. Probab. 32, 1077–1088], if not sharper, but in contrast do not require any longer the evaluation of a two-dimensional or a one-dimensional integral.     

Surface-enhanced Raman scattering of 4,4′-bipyridine on silver by density functional theory calculations

Surface-enhanced Raman scattering (SERS) of 4,4′-bipyridine (BPy) on silver foil substrate was measured using the 488, 514.5, and 1064 nm excitation lines. Density functional theory (DFT) methods were used to calculate the structure and vibrational spectra of Ag–BPy, Ag₃–BPy and Ag₄–BPy complexes with B3LYP/6-31++G(d,p)(C,H,N)/Lanl2dz(Ag) basis set. The Raman bands of BPy were assigned on the basis of the calculation of potential energy distribution. The calculated spectra of Ag–BPy and Ag₄–BPy complexes were much closer to the experimental results of BPy adsorbed on silver surface than that of Ag₃–BPy complexes. The vibrational frequencies that are sensitive to the planar or non-planar structure of BPy and to the dihedral angle of two pyridyl rings were discussed. The DFT results showed that the angles between two pyridyl rings for Ag–BPy and Ag₄–BPy were skewed by about 38.44° and 37.1°, respectively. The energy gaps of the HOMO and LUMO from DFT were 415–912 nm for BPy–Ag complexes. The relative intensities of SERS bands changed with different excitation laser lines. Thus, a chemical enhancement mechanism should play an important role in the SERS of BPy on silver substrate.     

时变大系统的区间矩阵平稳振荡

本文利用李亚普诺夫函数方法和平均法给出了时变大系统存在区间矩阵平稳振荡的充分条件，推广了文「４」的相应定理。     

极化（e,2e）碰撞电离的研究进展

传统（ｅ，２ｅ）谱学已成为研究原子和分子电子结构和电离机制的强有力工具之一，本文首先简要回顾了迄今国内外传统（ｅ，２ｅ）谱学研究的历史和现状。然后，再重点介绍近几年开展极化（ｅ，２ｅ）碰撞电离研究的进展。