Static fatigue fracture of polyethylene: A morphological analysis

The fracture properties of a number of high-density polyethylenes were evaluated and related to their morphology. The resistance to initiation of fracture is related to the resistance to voiding of the materials and the rate of coalescence of voids. The propensity of the materials to void has been shown to be related to the size of the amorphous region. The resistance to propagation of the fracture is also related to the above factors as well as the ease of stretching and rupture of fibrils. The ease of fibril formation has been shown to be related to the degree of perfection of the crystallites.     

Explicit finite difference simulations for accelerating cross diffusion flow over a perpendicular shield with parabolic motion

The heat transfer phenomenon subject to thermos-diffusion effects convey important applications in the heating processes, extrusion systems, chemical processes and various engineering systems. The objective of current work is to observe the contribution of Soret and Dufour effects in oscillating shield for cross diffusion flow. The perpendicular shield with oscillating motion induced the flow. The magnitude of oscillations is assumed to be small so that laminar flow due to oscillating shield has been resulted. The motivations for addressing the thermos-diffusion phenomenon due to oscillating of shield are due to applications in oscillatory pumps, moving surface, metal detectors, power systems etc. The dimensionless problem is obtained via introducing the appropriate set of variables. The numerical outcomes are suggested by using the most interesting explicit finite difference scheme. The physical illustration for flow parameters is presented. Moreover, the aspect of physical quantities involving the flow are graphically reported.     

DataCite and DOI names for research data

The publication of research data is still not a widespread practice in many disciplines. The lack of acceptance of data as scientific output equal to scientific articles, and the lack of suitable infrastructures for the storage of data make it difficult to publish and cite data independently. The global consortium DataCite was established in 2009 to overcome the challenges of data citation. The aim of the consortium is to establish easy access to data, to increase the acceptance of data publication and to support data archiving. The use of Digital Object Identifiers (DOI) provides an easy method to access and re-use research data. The DOI facilitates the citation of data and therefore increases the availability and acknowledgement of research data.     

小波包分析用于重叠分析化学信号的处理

对小波包分析的算法进行了改进,并将此算法成功地应用于多组分重叠色谱信号的解析.结果表明,本文提出的算法解决了MRSD算法的不足,更适合处理分析化学信号,用于重叠信号的解析时不需重构(逆变换),简化了数据处理步骤,加快了数据解析速度,具有较强的解析能力.对于重叠色谱信号的解析,小波包分析比小波分析具有更强的解析能力.     

The Principle of Congruence

The application of the principle of congruence to the estimation of the properties of mixtures of homologues from the properties of pure components is reviewed. The principle can be used to estimate densities, enthalpies and activity coefficients in liquid mixtures, PVT properties of gaseous mixtures, and has been applied to the estimation of viscosities of mixtures. The extension to multicomponent mixtures appears to be valid in simple cases. The overlap into the general group contribution approach to the prediction of mixture properties is commented on.     

Monte Carlo simulations of a coarse grained model for an athermal all-polystyrene nanocomposite system

The structure of a polystyrene matrix filled with tightly cross-linked polystyrene nanoparticles, forming an athermal nanocomposite system, is investigated by means of a Monte Carlo sampling formalism. The polymer chains are represented as random walks and the system is described through a coarse grained Hamiltonian. This approach is related to self-consistent-field theory but does not invoke a saddle point approximation and is suitable for treating large three-dimensional systems. The local structure of the polymer matrix in the vicinity of the nanoparticles is found to be different in many ways from that of the corresponding bulk, both at the segment and the chain level. The local polymer density profile near to the particle displays a maximum and the bonds develop considerable orientation parallel to the nanoparticle surface. The depletion layer thickness is also analyzed. The chains orient with their longest dimension parallel to the surface of the particles. Their intrinsic shape, as characterized by spans and principal moments of inertia, is found to be a strong function of position relative to the interface. The dispersion of many nanoparticles in the polymeric matrix leads to extension of the chains when their size is similar to the radius of the dispersed particles.     

Resolution of a distribution of distances by fluorescence energy transfer and frequency-domain fluorometry

We used frequency-domain fluroscence spectroscopy to examine the intensity decays of a fluorescent donor attached to an acceptor via a flexible alkyl chain. The intensity decay of the indole donor becomes markedly heterogenous due to energy transfer to the densyl acceptor. The measured dispersion of fluroscence decay times was used to recover the donor-to-acceptor distance distribution. The distance distribution was found to be characteristic of the molecule, and not the model used for data analysis. The ability to recover distance distributions in solution should be valuable in studies of biological macromolecules.     

Herman-Kluk semiclassical dynamics in action-angle representation: new approaches to mapping quantum degrees of freedom

A general approach to mapping a discrete quantum mechanical problem by a continuous Hamiltonian is presented. The method is based on the representation of the quantum number by a continuous action variable that extends from -infinity to infinity. The projection of this Hilbert space onto the set of integer quantum numbers reduces the Hamiltonian to a discrete matrix of interest. The theory allows the application of the semiclassical methods to discrete quantum mechanical problems and, in particular, to problems where quantum Hamiltonians are coupled to continuous degrees of freedom. The Herman Kluk semiclassical propagation is used to calculate the nonadiabatic dynamics for a model avoided crossing system. The results demonstrate several advantages of the new theory compared to the existing mapping approaches.     

The critical temperatures of isomeric pentanols and heptanols

The critical temperatures of seven isomeric alcohols have been measured using the modified sealed tube method of Mogollon. The ampoule used in the Mogollon method was modified to allow easier handling and reproducible results to be obtained. The addition of an Apple IIe microcomputer to the apparatus made possible the recording of the temperature history of the fluid and the monitoring of successive meniscus disappearances and appearances with time. The critical temperatures were obtained by averaging the temperatures of meniscus disappearance and reappearance. The fill densities of the ampoules were approximately equal to the critical densities.     

Dielectric relaxation and phonon modes of NdCrO3 nanostructure

The neodymium chromate nanoparticles are synthesized by the sol–gel process. The phase formation with Pnma symmetry of the sample is confirmed by the Rietveld refinement of X-ray diffraction data. The particle size of the sample is determined by transmission electron microscopy. The band gap of the material is found to be 1.78 eV which is obtained by Tauc relation to UV-absorption spectrum. The room temperature Raman spectrum is fitted with the sum of 22 Lorentzian peaks. Dielectric relaxation of the sample has been investigated in the frequency range from 42 Hz to 1.1 MHz and in the temperature range from 303 to 573 K. The Cole–Cole model is used to explain the dielectric relaxation mechanism of the material. The complex impedance plane plot confirms the existence of the grain-boundary contribution to the relaxation of the sample. The frequency-dependent conductivity spectra follow the power law.     

Hybridized particle swarm algorithm for adaptive structure training of multilayer feed-forward neural network: QSAR studies of bioactivity of organic compounds

The multilayer feed-forward ANN is an important modeling technique used in QSAR studying. The training of ANN is usually carried out only to optimize the weights of the neural network and without paying attention to the network topology. Some other strategies used to train ANN are, first, to discover an optimum structure of the network, and then to find weights for an already defined structure. These methods tend to converge to local optima, and may also lead to overfitting. In this article, a hybridized particle swarm optimization (PSO) approach was applied to the neural network structure training (HPSONN). The continuous version of PSO was used for the weight training of ANN, and the modified discrete PSO was applied to find appropriate the network architecture. The network structure and connectivity are trained simultaneously. The two versions of PSO can jointly search the global optimal ANN architecture and weights. A new objective function is formulated to determine the appropriate network architecture and optimum value of the weights. The proposed HPSONN algorithm was used to predict carcinogenic potency of aromatic amines and biological activity of a series of distamycin and distamycin-like derivatives. The results were compared to those obtained by PSO and GA training in which the network architecture was kept fixed. The comparison demonstrated that the HPSONN is a useful tool for training ANN, which converges quickly towards the optimal position, and can avoid overfitting in some extent.     

Preliminary evaluation of interactions between selected alcoholamines and model skin sebum components

The aim was to evaluate the interaction between selected alcoholamines and components of artificial skin sebum. The rate and depth of penetration into the lipophilic bead imitating pilosebaceous unit lumen was applied for alcoholamine penetration activity assay. The activity differentiation of 0.5% aqueous alcoholamine solutions with a potential cleansing effect on the pilosebaceous unit was performed. The depth of aminomethylpropanol penetration increased from 0.080 mm after 15 min to 3.049 mm after 72 h. The depth of aminomethylpropendiol penetration increased with time from 0.148 to 4.064, respectively, of diisopropanolamine from 0.481 to 4.626, triethanolamine from 0.236 to 4.342, triisopropanolamine from 0.275 to 2.392 and trometamol from 0.338 to 4.580. The products of alcoholamines reaction with the model skin sebum are easily dispersed in water. The rate of alcoholamines reaction with the model skin sebum depends on the alcoholamine, being the highest in the case of diisopropanolamine, decreasing to minimum for triisopropanolamine. Selected alcoholamines would be applied in ex vivo and in vivo research.     

铜基催化剂的制备方法对草酸二乙酯加氢反应的影响

草酸二乙酯加氢性成乙二醇的反应过程中，所用的铜基催化剂是由Ｃｕ（ＮＯ３）２与硅溶胶凝法制得的。本文考察了该催化剂的ＴＰＲ特性，结果表明，随着催化剂中Ｃｕ／ＳｉＯ２值的增大，其ＴＰＲ主峰ＴＭ峰温有所升高，这意味着催化剂的还原温度随Ｃｕ／ＳｉＯ２值的增大而提高。用ＸＲＤ和ＸＰＳ等手段对该催化剂还原后铜的含量及价态进行了考察，表明用胶凝法制备的铜基催化剂，还原后存在Ｃｕ＾ｏ和Ｃｕ＾＋两种价态。结合活性评     

Ionisation Energies and the Electronic Structures of the N-oxides of diazabenzenes

The ionisation energies and the HeI photoelectron spectra of the N-oxides of diazabenzenes are presented. The valence electronic structures of the N-oxides are discussed in view of the ionisation energies, and the profiles, of the bands. The interpreted data are compared to calculations which are in good agreement. The results are correlated to the physicochemical studies, and particularly to the electronic absorption spectroscopy, of the N-oxides. The assignment of the photoelectron spectra of the azabenzenes are considered with reference to the spectra of their N-oxides.     

Kinetic regularities of erythrocyte hemolysis and hemoglobin oxidation under the action of sulfur-nitrosyl iron complexes as nitric oxide donors

The kinetics of erythrocyte hemolysis and intra-erythrocyte hemoglobin oxidation under the action of synthetic sulfur-nitrosyl iron complexes was studied. The complexes capable of releasing nitric oxide due to spontaneous hydrolytic decomposition was studied. The addition of these complexes to a 0.2% suspension of mouse erythrocytes results in hemolysis. The kinetic curves of hemolysis exhibit an induction period, whose duration is different for each complex. The hemolysis is preceded by hemoglobin oxidation with nitric oxide penetrating into the cell. The oxidation of hemoglobin follows the first-order rate equation. The apparent first-order rate constants characterizing the NO-donating ability of each complex were determined. The hemolytic effect of the studied complexes is suggested to be related to the formation of peroxynitrite inside erythrocytes. Peroxynitrite is the cytotoxic product of interaction of nitric oxide and the superoxide radical anion.     

钴卟啉过氧中间体向环己烷夺氢的密度泛函计算

采用密度泛函理论计算方法模拟了简单钴卟啉过氧中间体PCo-O2与环己烷C6H12的作用,分析了反应路径中各驻点能量和反应过渡态分子构型。研究结果表明,PCo-O2向底物环己烷夺氢的反应可以延正方向进行,二线态PCo-O2更具反应活性,反应过程中Co-O键得到加强,O-O键被削弱。依据理论计算结果,探讨了四苯基钴卟啉催化环己烷氧化生成环己醇和环己酮的反应机理,指出反应延Lyons高价金属氧代物机理生成环己醇,而反应循环中产生的烷基自由基可以延烷基过氧化过渡金属配合物反应机理进行生成环己酮。     

Inclined surface slip flow of nanoparticles with subject to mixed convection phenomenon: Fractional calculus applications

The interest of researchers towards the nanofluids is noticed in recent years due to leading applications in thermal systems and industrial framework. Referring to such motivations, current study explores the role of velocity slip effects for the mixed convection flow of nanofluid endorsed due to inclined surface. The Casson base fluid model for which the thermal impact needs to be improved. The analysis is observed when the role of velocity slip is important. The modeling of unsteady free convective flow problem yields partial differential system. The Atangana-Baleanu (AB) and Caputo-Fabrizio (CF) fractional operators are implemented in order to simulates the computation of problem. The graphical presentations are prepared in order to check the physical dynamic of parameters.     

Use of basic amphiprotic organic solvents containing neutral-surfactant aggregates as pseudostationary phase in non-aqueous capillary electrophoresis

A new approach to non-aqueous capillary electrophoresis based on the addition of anionic carboxylic surfactants to the basic amphiprotic organic solvent in which form neutral-surfactant aggregates was developed with a view to improving the electrophoretic resolution of charged substances. These aggregates acts as a new pseudostationary phase. The presence of these aggregates allows the effective separation of four tetracyclines with increased selectivity. The efficiency of sodium caprylate, sodium laurate and sodium palmitate as surfactants was examined. The latter two proved more effective than the former as they provided migration times reproducible to within 7% or better in all cases. The additional use of an alcohol allows peak shape to be controlled, which expands the potential of this electrophoretic technique even further. The proposed method was used to determine tetracyclines in water samples. The sensitivity of the determination was improved by using a flow manifold coupled at-line to the capillary electrophoresis system in order to preconcentrate the analytes. The limits of detection thus achieved ranged from 50 to 90 μg/l. Under optimal operating conditions, recoveries ranged from 97 to 104%, and precision from 5.4 to 7.0%.     

A push/pull surface-mode liquid-crystal shutter: Technology and applications

The construction, operating principles and electro-optics of a surface-mode liquid-crystal shutter are reviewed. The shutter is composed of two glass plates, the inner surfaces of which are coated with a transparent electrically conductive layer. The substrates are treated to induce parallel director alignment. Polarizers are placed on the front and back of the cell oriented at right angles to each other and at 45° to the director. In the surface mode of operation a sustaining voltage is applied to the cell. This causes the director in the centre of the cell always to be oriented parallel to the electric field. The amplitude of the applied voltage determines the thickness of the surface layer-the layer in which the director orientation varies from parallel to the surface to parallel to the electric field. Light travelling through the cell will encounter retardation only in the surface layers. Hence the voltage controls the retardation of the cell, and by that means the polarization state of the light travelling through the cell. By adjusting the voltage so that the retardation is changed from 0λ to ½λ the shutter can switch from open to closed. It is possible to construct a faster-switching shutter. This so-called push/pull shutter is composed of three elements in optical series. The first two are surface-mode cells oriented such that their directors are perpendicular. The third element is a quarter-wave plate with its axes parallel to the directors. The three elements are placed between orthogonal polarizers, with the directors oriented at 45° to the polarizers axes. The closed state of the shutter is obtained by placing one shutter in the high-voltage 0λ state and the other in the low-voltage ¼λ state. The open state of the shutter is obtained by switching the voltage levels applied to the two cells. The operating principles and the electro-optics of this device are discussed in detail.     

The paramagentic resonance principles and fundamental parameters in powder spectra

The EPR principles are reviewed. The interaction of the unpaired electron with various local fields was shown to give rise to perturbations which help to define the environment of the electron spin. The principal magnetic parameters are defined and related to the physical parameters of the paramagnetic substances. The use of the g̃ and à magnetic parameters in the case of a single unpaired electron is illustrated in various characteristic cases. The identification of the paramagnetic center and the determination of lattice crystal fields were shown to be possible through the use of g̃ principal components. Further information about the nature and the structure of the paramegnetic center and its close environment is shown to be obtainable from the variation of spin-spin and spin-nuclear interactions.The cases where more than a single unpaired electron exist at a particular center are considered and the relevant additional parameters defined and their significance with respect to the symmetry of the center is examined.