On Sampling Stationary Stochastic Processes

A quasi Fourier-type duality associated with a bandlimited stationary stochastic process can be established. It comes from the spectral representation of the process and a compact support assumption for its spectral density. In this way, for essentially bounded spectral densities we have an isometry between a weightedL²space and the Hilbert space spanned by the process. We can transfer converging expansions for the exponential complex e^itw in the :L²-space into a sampling expansion for the process converging in the mean square sense.     

Dynamic Dipole and Quadrupole Phase Transitions in the Kinetic Spin-3/2 Model

The dynamic phase transition has been studied, within a mean-field approach, in the kinetic spin-3/2 Ising model Hamiltonian with arbitrary bilinear and biquadratic pair interactions in the presence of a time dependent oscillating magnetic field by using the Glauber-type stochastic dynamics. The nature (first- or second-order) of the transition is characterized by investigating the behavior of the thermal variation of the dynamic order parameters and as well as by using the Liapunov exponents. The dynamic phase transitions (DPTs) are obtained and the phase diagrams are constructed in the temperature and magnetic field amplitude plane and found nine fundamental types of phase diagrams. Phase diagrams exhibit one, two or three dynamic tricritical points, and besides a disordered (D) and the ferromagnetic-3/2 (F_3/2) phases, six coexistence phase regions, namely F _3/2+ F _1/2, F _3/2+ D, F _3/2+ F _1/2+ FQ, F _3/2+ FQ, F _3/2+ FQ + D and FQ + D, exist in which depending on the biquadratic interaction. PACS number(s): 05.50.+q, 05.70.Fh, 64.60.Ht, 75.10.Hk     

Spectroscopic and Analytic Properties of New Copper(II) Complex of Antiviral Drug Valacyclovir

The complexation processes between Cu^II and the antiviral drug, valacyclovir hydrochloride (H₂L), were studied under different reaction conditions, using UV-Vis, IR and mass spectra, magnetochemical, thermogravimetric, atomic absorption, conductivity, and elemental analysis data. Using the Job method, the compositions of these complexes were determined. Under the ligand (H₂L) excess (M:L = 1:1–1:10). In aqueous solutions, a binuclear violet complex Cu₂(HL)₂L(H₂O)₄ is formed, with an octahedral structure. Under comparable amounts of the reagents, in MeOH solutions, a green mononuclear complex Cu(H₂L)Cl₂ is formed. Protonation constants of the H₂L, and stability constants of its Cu²⁺ complexes, were determined by potentiometric titration in H₂O media at 25 ± 0.02 °C under a N₂ atmosphere and ionic strength of 0.1 m NaCl. It has been observed that H₂L has three protonation constants. The divalent metal ion Cu²⁺ forms stable 2:1 and 2:2 complexes with H₂L. The antimicrobial activity studies of the valacyclovir and it’s complexes have been studied against some gram positive species: (Corynebacterium xerosis, Bacillus brevis, Bacillus megaterium, Bacillus cereus, Mycobacterium smegmatis, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis) and gram negative (Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Yersinia enterocolitica, Kluyveromyces fragilis, Saccharomyces cerevisiae, Candida albicans) bacteriaz.     

Residence time distribution study for the catalytic packing MULTIPAK®

Residence time distribution (RTD) experiments were carried out using the catalytic packing MULTIPAK® in a 250 mm inner diameter column. The axial dispersion coefficients and dynamic liquid hold-up were derived from the RTD curves. Both hold-up and axial Péclet number were correlated in terms of gas and liquid Reynolds numbers. Free-draining experiments were performed to determine the dynamic and static liquid hold-ups. The measured axial dispersion coefficients were higher than those presented in other studies. The dynamic hold-up derived from RTD agreed with total hold-up from free-draining experiments. The static hold-up was found very high, even higher than the dynamic one, due to the liquid accumulated inside the catalyst bed. Possibly, the liquid considered “static” from the viewpoint of the free-draining experiments becomes “dynamic” during the normal column operation.     

Experimental and Theoretical Spectral(FT-IR,Raman,NMR,UV-Vis and NLO)Analysis of a Potential Anti-Tumor Drug:1-Methyl-6-Nitro-1H-Benzimidazole

In the present work, the experimental and the theoretical spectroscopic properties of 1-Methyl-6-Nitro-1H- Benzimidazole were investigated. The FT-IR (400~4 000 cm-1) and FT-Raman spectra (100~4 000 cm-1) of 1-Methyl-6-Nitro-1H- Benzimidazole in the solid phase were recorded. Also, experimental NMR and UV spectra of titled molecule were measured. To interpret the experimental data, geometric parameters, vibrational frequencies, NMR, UV spectra and NLO analysis of the optimized molecule were calculated using ab initio Hartree–Fock (HF) method and density functional theory (B3LYP) method with the 6-31++G(d,p) and 6-311++G(d,p) basis sets. Vibrational bands were assigned based on the potential energy distribution using the VEDA 4 program. The theoretical results showed good agreement with the experimental values.     

New ionic liquids for modification of chitin particles

Research on Chemical Intermediates - Chitin particles are chemically and mechanically stable due to the strong inter- and intra-sheet network of hydrogen bonds and the large number of crystalline...     

阴离子表面活性剂存在下吖啶橙—罗丹明B混合体系能量转移研究

本文以吖啶橙和罗丹明Ｂ作为能量转移中的给予体和接受体，分别探讨了不同阴离子表面活性剂对染料问能量转移影响。从染料分子所处微环境变化的角度阐明了分子聚集状态的变化是影响能量转移效率的重要因素。     

Copper UPD on Selenium-Modified Polycrystalline Pt Electrode

Underpotential deposition of Cu onto an Se-modified smooth polycrystalline Pt electrode in an acidic CuSO₄ solution was investigated using a cyclic voltammetry. It was obtained that the specific voltammetric pattern of Cu UPD observed for a clean Pt electrode disappeared and a new current peak at potentials much closer to bulk Cu deposition was formed. This feature of a cyclic voltammogram is similar to that observed earlier for clean Pt electrode in acidic CuSO₄ solutions containing selenite and also to that described for S-modified Pt electrode in an additive-free CuSO₄ solution. The reasons for the difference in the voltammetric behavior of bare Pt and Se-modified Pt in the potential range characteristic of Cu UPD were considered. A model of Cu deposition taking place onto the free Pt sites at more positive potentials and onto the Se-covered ones at less positive potentials was discussed with closer scrutiny.     

Temperature effects on positronium formation in solution of sodium acetate in methanol

The influence of the acetate ion (Ac^? in solutions of methanol on the Ps yield has been examined at 203, 248 and 294 K. Ac^? was found to be both a strong “limited” inhibitor through e⁺ scavenging and an enhancer through hole trapping. The temperature effects observed are interpreted by a change in the relative probabilities ofthe two processes.