The spherical-model limit in a random field

The spherical-model limitn of then-vector model in a random field, with either a statistically independent distribution or with long-range correlated random fields, is studied to demonstrate the correctness of the replica method in which then and replica limits limits are interchanged, provided the replica and thermodynamic limits are taken in the right order, in the case of long-range correlated random fields. A scaling form for the two-point correlation function relevant to the first-order phase transition below the lower critical dimensionality of the random system is also obtained.     

New Aspects of Cyclodextrin Chemistry Induced by Outside Type Complex Formation; Asymmetric Reduction of Indol-3-Pyruvic Acid with NaBH4 in Aqueous Solution

Asymmetric reduction of indol-3-pyruvic acid (IPA) with NaBH₄ in aqueous solution in the presence of various cyclodextrins (α-, β-, γ-, mono-6-amino-6-deoxy-β- and di-6^ABamino-6^AB-deoxy-β-cyclodextrin) was investigated. From the NMR and circular dichroism spectral studies, the conformation of the CyD–substrate complexes is suggested; the part of carboxylic group stay in the cavity of α-CyD, whole of IPA in β-CyD, two molecules in a γ-CyD cavity, and IPA(s) is/are on the rim of the cavity of mono-6-amino-6-deoxy-β- and di-6^ABamino-6^AB-deoxy-β-CyD (AβCyD, DAβCyD) with electrostatic interaction between amino group and carboxylic group. This conformational difference provides in the difference in the optical selectivity of reduction.     

Parametric study of the flow and temperature fields in an inductively coupled r.f. plasma torch

A theoretical investigation of the effect of different parameters on the flow and the temperature fields in a radiofrequency inductively coupled plasma is carried out. The parameters studied are: central injection gas flow rate, total gas flow rate, input power, and the type of plasma gas. The results obtained for argon and nitrogen plasmas at atmospheric pressure indicate that the flow and the temperature fields in the coil region, as well as the heat flux to the wall of the plasma confinement tube, are considerably altered by the changes in the torch operating conditions.     

Monte Carlo simulation of polarizable systems: Early rejection scheme for improving the performance of adiabatic nuclear and electronic sampling Monte Carlo simulations

An early rejection scheme for trial moves in adiabatic nuclear and electronic sampling Monte Carlo simulation (ANES-MC) of polarizable intermolecular potential models is presented. The proposed algorithm is based on Swendsen–Wang filter functions for prediction of success or failure of trial moves in Monte Carlo simulations. The goal was to reduce the amount of calculations involved in ANES-MC electronic moves, by foreseeing the success of an attempt before making those moves. The new method was employed in Gibbs ensemble Monte Carlo (GEMC) simulations of the polarizable simple point charge-fluctuating charge (SPC-FQ) model of water. The overall improvement in GEMC depends on the number of swap attempts (transfer molecules between phases) in one Monte Carlo cycle. The proposed method allows this number to increase, enhancing the chemical potential equalization. For a system with 300 SPC-FQ water molecules, for example, the fractions of early rejected transfers were about 0.9998 and 0.9994 at 373 and 423 K, respectively. This means that the transfer moves consume only a very small part of the overall computing effort, making GEMC almost equivalent to a simulation in the canonical ensemble.     

Structure formation and dynamics of water in strong external electric fields

We have performed molecular dynamics computer simulations of water in homogeneous external electric fields which were varied in a wide range of field strengths. The dielectric response is found to be linear up to fields E₀≈0.01 V/Å from where dielectric saturation effects become important. At fields of E₀≈3 V/Å a phase transition into an ordered, ice-like structure is observed, which is stabilized through hydrogen-bonds. With an increasing external electric field, the frequency spectrum of the water dynamics shows a remarkable red shift of the intramolecular modes and a blue shift of the librational motions, where the frequency varies quadratically with the field strength. A simple analytical model is discussed which reproduces the observed behavior.     

Enthalpic determinations of aliphatic ester-solvent systems with correlations

Calorimetric measurements were carried out on ester-solvent systems where the esters were H(CH₂)_xCOO(CH₂)_yH, with x and y varying from 1 to 5, and the solvents were n-hexane and 1,2-dichloroethane. Calculation of the enthalpies of cavity formation enabled the enthalpies of interaction to be determined. Both enthalpies correlated with number of carbon atoms N, equal to x+y in the esters, giving for 1,2-dichloroethane

Gaussian,non-Gaussian critical fluctuations in the Curie-Weiss model

It is known that at the critical temperature the Curie-Weiss mean-field model has non-Gaussian fluctuations and that internal fluctuations can be Gaussian. Here we compute the distribution of theq-mode magnetization fluctuations as a function of the temperature, the wave vectorq, and a fading out external field. We obtain new classes of probability distributions generated by this external field as well as new critical behavior in terms of its rate of fading out. We discuss also the susceptibility as the limitq tending to zero.     

腔靶X射线辐射对称特性实验观测

在“神光”装置上用两种特殊结构的实验靶型,通过两个不同方位的诊断孔观测腔内壁Ｘ光再辐射的空间能谱结构和Ｘ光辐射总量,分别研究了与激光第一打击面完全对称和不对称的腔内壁（两个被观测位置相差９０°）Ｘ光辐射能谱和辐射能量的对称性,并对测量结果进行了简要的分析讨论．     

On quadratic forms of height two and a theorem of Wadsworth

Let and be anisotropic quadratic forms over a field of characteristic not . Their function fields and are said to be equivalent (over ) if and are isotropic. We consider the case where and is divisible by an -fold Pfister form. We determine those forms for which becomes isotropic over if , and provide partial results for . These results imply that if and are equivalent and , then is similar to over . This together with already known results yields that if is of height and degree or , and if , then and are equivalent iff and are isomorphic over .

     

Enzymatic hydrolysis reaction of phospholipids in monolayers

The hydrolysis reaction of , and , -dipalmitoylphosphatidylcholine (DPPC) catalized by bee venom phospholipase A₂ was studied in spreading monolayer at the water/air interface. DPPC and the hydrolysis products, palmitic acid and -lysophosphatidylcholine, palmitoyl were characterized at the interface by means of surface pressure, surface potential and ellipsometric measurements. Furthermore, mixed monolayers of reagents and products were investigated to ascertain their miscibility. The results show that the hydrolysis reaction can be followed by the decrease of surface pressure with time on subphases containing β-cyclodextrin, a well-known complexing agent of many amphiphilic compounds. The order of the reaction, the kinetic constant and other kinetic parameters are deduced.