The solute–solvent interactions of some phenol derivatives were investigated potentiometrically in 0–60 % (v/v) ethanol–water mixtures. The acidity constants values were correlated with either macroscopic parameters such as molar fraction, permittivity and the solvating ability or microscopic parameters, such as the Kamlet–Taft solvatochromic parameters. Moreover, it is demonstrated that the pKa values in any ethanol–water mixtures are linearly related to the pKa values of the phenols in pure water. The slope and intercept parameters of the linear correlations are related with the mole fraction of ethanol. These equations permit accurate calculation of the pKa values of the studied phenols at any ethanol–water composition. 相似文献
Photoactivated cross-linking of peptides to proteins is a useful strategy for identifying enzyme-substrate and protein-protein interactions in cell lysates as demonstrated by studies on the human hypoxia inducible factor system. 相似文献
This paper presents the dynamic feedforward control synthesis for linear parameter varying (LPV) systems. It is assumed that all system matrices are dependent on varying parameters, which are measurable with sensor or observable. The parameters have bounded variation rates. Parameter-dependent Lyapunov function is used for the feedforward control synthesis such that the robust stability is assured for all varying parameters at the time of the operation. The method is formulated in terms of linear matrix inequalities for LPV feedforward controller that guarantees the stability of the transfer matrix having \(L_{2}\)-gain. This compensator is designed by adding on the feedback controller in two degrees of freedom control configuration. This controller can be used for the disturbance attenuation or decreasing the tracking error. The numerical examples and simulations are given to provide the applicability of the proposed solution. 相似文献
A near-infrared metamaterial design that is reconfigurable between almost completely transmissive and reflective states is presented. The reconfiguration is enabled by tuning the anisotropic nematic liquid crystals used as a spacer layer between two silver nanoplates in a planar doubly periodic metamaterial. The design is optimized for maximum difference in transmittance between the two states by using a genetic algorithm. For a linearly polarized illumination at normal incidence, full-wave electromagnetic analysis predicts that the optimized metamaterial film can change the transmittance between 98.7% and 0.1% at a wavelength of 1.1 microm. 相似文献
We present a clear signature of the Schottky effect in a rf photoinjector using photons with energy lower than the Mg cathode work function. This signature is manifested by the shift in the rf phase angle for the onset of the detection of photoelectrons via single-photon absorption and allows for a reasonable estimate of the field enhancement factor. This is a viable method to generate an electron beam with very low thermal emittance and thus, a high brightness beam. 相似文献
The natural radioactivity levels and some radiological parameters of Turkish Portland cements (PC) originated in various regions were determined in this study. The activity concentration of cement samples for 226Ra, 232Th, and 40K were measured using a gamma-ray spectrometer with high purity germanium radiation detector. The PC samples had activity concentrations of 33.0, 16.7, and 239.5 Bq kg−1 for 226Ra, 232Th, and 40K, respectively. The mean value of radium equivalent value (Raeq) was found to be 75.4 Bq kg−1. The radium equivalent values in the cement samples were lower than the acceptable level of 370 Bq kg−1. The calculated radiological parameters were found to be below the acceptance levels.
From the color developing reactions of o-phenylenediamine oxidizing agent and gold(III), the kinetic reactions between both of them in aquaeous solutions were studied using spectrophotometric and differential method. Light absorbances in the visible spectral range are measured as a function of mole fractions of phenylenediamine at a fixed gold(III) concentration and as a function of mole fraction of gold(III) at a fixed o-phenylenediamine concentration at periodic time internal. In the differential method, which was suggested by van't Hoff, one deals with the actual rates of reactions as determined by measuring the slopes of absorbance-time curves. Optimum condition of the reaction were established as pH 6 at lambda=466 nm and room temperature. When the oxidation of o-phenylenediamine by gold(III) was investigated, it was observed that the following rate formula and rate constant were found: v=k[Au+3]1/2[o-phenylenediamine]1/2, k=2.33x10(-2) s-1. 相似文献
In this paper, the investigation of the asymptotical stability of linear neutral systems with time-varying delay has been presented. In order to achieve the desired results, the integral inequality approach was used to express relationships between terms of Newton-Leibniz formula technique and was constructed an appropriate Lyapunov-Krasovskii functional. By improving a delay decay approach, the stability criteria for the zero solution of system were formulated as linear matrix inequalities (LMIs) which can be easily solved. Two numerical examples have been given to show the applicability of established assumptions and the effectiveness of proposed method by MATLAB-Simulink. 相似文献