Association Schemes with Multiple Q-polynomial Structures

It is well known that an association scheme with has at most two P-polynomial structures. The parametrical condition for an association scheme to have two P-polynomial structures is also known. In this paper, we give a similar result for Q-polynomial association schemes. In fact, if , then we obtain exactly the same parametrical conditions for the dual intersection numbers or Krein parameters.     

Equilibrium solubility of 6-propyl-2-thiouracil in nine pure solvents: Determination,correlation, Hansen solubility parameter and thermodynamic properties

Investigation upon the solid–liquid equilibrium on solubility data of 6-propyl-2-thiouracil (PLT) in pure organic solvents is essential for separation and purifying in industry process. In this work, PLT solubility in nine neat solvents was experimentally determined at 278.15 K–323.15 K under P = 0.1 MPa. These selected solvents were tetrahydrofuran(THF), acetone, acetonitrile,1-butanol,1-pentanol, 2-butanol, methyl acetate, ethyl acetate,1-propyl acetate, respectively. Experiment results showed that solubility was consistent with temperature and decreased according to the order: THF > acetone>1-butanol≈1-pentanol> 2-butanol > methyl acetate > ethyl acetate>1-propyl acetate > acetonitrile. Solvent effect and Hansen solubility parameter (HSP) were incited to explain dissolution rule on solute. Four thermodynamic models (modi?ed Apelblat model, Van't model, λh model and NRTL model) were adopted to correlate PLT solubility and provide good correlations on basis of RD, ARD and RMSD. In addition, thermodynamic properties (ΔH°, ΔS° and ΔG°) of PLT dissolution process in pure solvents were discussed and proved to be endothermic, entropically driven and non-spontaneous process.     

Decontamination of chemical warfare agents using perchloroethylene–Marlowet IHF–H2O-based microemulsions: wetting and extraction properties on realistic surfaces

At the present time, considerable efforts are being made to develop new media for the decontamination of a variety of toxic compounds. In the present contribution, new microemulsions with promising properties are presented. Moreover, the decontamination of surfaces, with an emphasis on varnished metal surfaces of exterior and interior equipment, is investigated using these microemulsions. Studies of the phase behavior of the system water–perchloroethylene–IHF–2-propanol are reported and the microemulsion phases are recognized. The wetting behavior on contaminated surfaces and the extraction capabilities with respect to contaminants are essential for an efficient decontamination. Hence, suitable microemulsions are identified on the basis of these properties. The decontamination efficiency of these microemulsions is first estimated on the basis of the ability to wet typical chemical nonresistant varnished steel sheets, which are authentic model systems for real surfaces. Afterwards, promising microemulsions and, as reference, different solvents are tested with respect to their capability to solubilize sulfur-mustard agent, again using realistic surfaces contaminated with this chemical warfare agent. Several microemulsions are found, which have the desired properties.     

Enantioseparation of Binaphthol and Its Derivatives on Cellulose Tris(3,5-dimethylphenyl carbamate)

A Chiralcel OD-H column was used for the normal phase enantioseparation of binaphthol and its derivatives. Unexpectedly, binaphthol and its dibromo-substituted analogue could not be enantioseparated fully, whereas its ether and ester derivatives gave complete or partial resolution. Aspects of the chiral recognition are discussed further through calculated thermodynamic parameters.     

Periodic behavior of collapse–revival phenomenon in the full nonlinear interaction between a three-level atom and a single-mode field

In this paper based on a generalization of the Jaynes–Cummings model we solve the dynamical Hamiltonian describing the interaction between a (Λ$\Lambda$ or V-type) three-level atom and a single-mode field in the “full nonlinear regime” and then the analytical form of state vector of the system is explicitly obtained. In this manner, we encountered with “intensity-dependent detuning” as well as “intensity-dependent atom–field coupling” in our two models. Via choosing an appropriate deformation function (which imposes nonlinearity to the system) we consider the influence of Kerr-like medium from which the resonance condition for a selected number of quanta is achieved (selective transition is occurred). Furthermore, by these considerations, we may find the optimum values for atom–field coupling constants which provide a regular periodic behavior of probability amplitudes for the two considered atomic systems. Moreover, to show this periodic time behavior, the temporal evolution of the probability of the allowed atomic transitions as well as the Mandel parameter (as a non-classical sign) is depicted for various circumstances. As is observed, complete revivals may appear in some particular situations.     

MISO的离散动力系统的最小二乘模型降阶方法

利用最小二乘原理,提出一个基于SVD-Krylov的模型降阶方法,方法兼顾基于SVD模型降阶方法的理论性质和基于Krylov模型降阶方法的有效计算,使得到的降阶系统既能匹配原系统的前r阶模,又能够保持系统的稳定性.利用对称矩阵特征值的极小极大原理,给出了保持系统稳定性的一个新的证明方法,与已有的方法相比,提出的理论证明方法更为简洁.对于离散系统,方法除了能匹配原模型的前r个Markov参数,还可将其推广到任意点处模匹配.数值例子也证明了方法的有效性.     

Optical and dielectric properties of an isothiocyanato liquid crystal compound and comparison of its behavior with that of a homologous member

The properties of an isothiocyanato liquid crystal compound (code name S1) has been studied with a view to compare its behavior with that of another member of its homologous series (code name S5). Optical properties, such as refractive index, polarisability, and their anisotropies, have been evaluated with varying temperature and the orientational order experimentally determined from the study of polarisability anisotropy and compared with theoretically computed values. Dielectric studies have been conducted to determine not only the dielectric anisotropy but also the effective molecular dipole moment and its temperature dependence. The temperature variation of the angle of inclination (β) of molecular dipole moment with the director direction has also been determined and compared with that of S5. In order to determine the nature of molecular association in the mesophase, the molecular correlation factor (g) has been estimated from the measurements of dipole moments of compound in solution and compared with the values obtained for S5.     

Quasi-Reversibility Method for an Ill-Posed Nonhomogeneous Parabolic Problem

The quasi-reversibility method is considered for the non-homogeneous backward Cauchy problem u_t+Au = f(t), u(τ) = ? for 0≤t<τ, which is known to be an ill-posed problem. Here, A is a densely defined positive self-adjoint unbounded operator on a Hilbert space H with given data f∈L¹([0,τ],H) and ?∈H. Error analysis is considered when the data ?, f are exact and also when they are noisy. The results obtained generalize and simplify many of the results available in the literature.     

Approach on quantitative structure-activity relationship for design of a pH neutral carrier containing tertiary amino group

The quantitative structure-activity relationship (QSAR) for neutral carriers used to prepare hydrogen ion sensors has been studied. A series of synthesized carrier compounds were taken as the training set. Five molecular structure parameters of the compounds were calculated by using CNDO/2 algorithm and used as feature variables in constructing QSAR model. The lower and upper limits of the linear pH response range were taken as the activity measure. The corresponding model equations were derived from the stepwise regression procedure. With the established QSAR model, a new pH carrier, (4-hydroxybenzyl) didodecylamine (XIII) was proposed and synthesized. The PVC membrane pH electrode based on carrier XIII with a wide pH linear response range of 2.0-12.5 was prepared. Having a theoretical Nernstian response slope of 57.2 ± 0.3 mV/pH (n = 5 at 25 °C) without a super-Nernstian phenomenon, the sensor had low resistance, short response time, high selectivity and good reproducibility. Moreover, the sensor was successfully applied to detecting the pH value of serum samples.