The best L 1-approximations of classes of functions defined by differential operators in terms of generalized splines from these classes

For classes of periodic functions defined by constraints imposed on the L ₁-norm of the result of action of differential operators with constant coefficients and real spectrum on these functions, we determine the exact values of the best L ₁-approximations by generalized splines from the classes considered. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 11, pp. 1443–1451, November, 1998.     

Contribution of superstring <Emphasis Type="Italic">Z</Emphasis>′ boson on the polarization effects in proton proton collisions

In this work we investigate the single- and the double-spin asymmetries at the collisions of polarized protons pp → (γ ^*, Z ⁰, Z′) + X within the scope of QCD, the electroweak interaction and superstring E ₆ theory. The helicity amplitude method is used. Analytical expressions for the single- and the double-spin asymmetries are obtained and their dependence on the transverse momentum of the lepton pair is investigated at the three different values of invariant masses of the lepton pair. The pure contribution coming from the superstring Z′ boson on the single- and double- spin asymmetries has been extracted. The results obtained allow investigation of the spin structure of the proton.     

Multiwall Carbon Nanotube‐Ionic Liquid Modified Paste Electrode as an Efficient Sensor for the Determination of Diazepam and Oxazepam in Real Samples

A carbon‐based electrode using multiwall carbon nanotube as a modifier and room temperature ionic liquid as a binder has been applied for the determination of diazepam (DZP) and oxazepam (OZP) in real samples including serum, urine and tablets. Square wave voltammetry as an appropriate electrochemical technique was applied to achieve improved limits of detection and higher sensitivities. The electrochemical studies were investigated under various experimental conditions such as pH, buffer concentration, ionic strength, deposition potential, deposition time and scan rate to achieve higher sensitivities. Linear concentration ranges for DZP and OZP were 0.02–0.76 mg L^?1 and 0.05–1.90 mg L^?1 with the detection limits of 4.1 µg L^?1 and 5.8 µg L^?1, respectively. The proposed method was successfully applied for the analysis of commercially available tablets as well as serum and urine samples and satisfactory results were obtained.     

Structure and electromagnetic behavior of nanocrystalline SrMgxZrxFe12−2xO19 in the 8–12 GHz frequency range

Nanocrystalline strontium hexaferrite doped with Zr–Mg is synthesized by the citrate sol–gel process. The cationic site preferences of Mg⁺² and Zr⁺⁴ in Mg–Zr substituted Sr ferrite were investigated by magnetic measurements and X-ray diffraction (XRD) analysis. Microwave absorption properties have been measured in the frequency range of 8–12 GHz. The results indicate that these ferrite particles have a significant potential for microwave absorption applications in the future.     

Study on continuous (254 nm) and pulsed UV (266 and 355 nm) lights on BVD virus inactivation and its effects on biological properties of fetal bovine serum

Both continuous UV lights and pulsed UV lasers have potentials to inactivate known and emerging viruses. Bovine viral diarrhea virus (BVDV), from the Pestivirus genus, is known to be a common viral contamination in (fetal) bovine serum (FBS). Also, BVDV has been used in the blood product industry as a surrogate for Hepatitis C virus (HCV), due to its similarity in structure and genome. Germicidal UV lamp with the wavelength of 254 nm and Nd:YAG laser (pulsed UV laser) in its third and fourth harmonic with the wavelengths of 355 and 266 nm, respectively, were used. BVDV suspended in PBS or FBS were exposed to different intensities and doses and then reduction in BVDV titer were calculated. To complete inactivation of BVDV suspended in PBS and PBS containing 5% FBS, 1.6 (t = 30 min) and 3.2 (t = 60 min) J/cm² were used. The minimum doses for inactivation of BVDV suspended in PBS with the 355 and 266 nm of pulsed UV laser were 352 and 92.25 J/cm². Also, the minimum doses for inactivation of BVDV suspended in FBS with 355 and 266 nm wavelengths of pulsed UV laser were 704 and 127 J/cm². To evaluate the irradiated FBS quality to support cell culture growth, FBS was treated with the dose of 190.5 J/cm² and 266 nm pulsed UV laser and was used to grow Vero cells, in comparison with a control group. The viability of cells in two groups was identical and the statistical evaluation showed no significant difference in 12 passages.     

Multiscale modeling of the surfactant mediated synthesis and supramolecular assembly of cobalt nanodots

Multiscale simulations are used to bridge the surfactant templated assembly of individual approximately 1-10 nm cobalt dots, to their ordering into supramolecular arrays. Potential energy surfaces derived from ab initio calculations are input to lattice Monte Carlo simulations at atomic scales. By this process we quantitatively reproduce the experimental cobalt nanoparticle sizes. Crucially, we find that there is an effective short range attraction between pairs of nanodots. Mesoscale simulations show that these attractive interdot potentials are so short ranged that the dots can assemble only into orientally ordered hexatic phases as in the experiments.     

Parallel comparison algorithms for approximation problems

Suppose we haven elements from a totally ordered domain, and we are allowed to performp parallel comparisons in each time unit (=round). In this paper we determine, up to a constant factor, the time complexity of several approximation problems in the common parallel comparison tree model of Valiant, for all admissible values ofn, p and , where is an accuracy parameter determining the quality of the required approximation. The problems considered include the approximate maximum problem, approximate sorting and approximate merging. Our results imply as special cases, all the known results about the time complexity for parallel sorting, parallel merging and parallel selection of the maximum (in the comparison model), up to a constant factor. We mention one very special but representative result concerning the approximate maximum problem; suppose we wish to find, among the givenn elements, one which belongs to the biggestn/2, where in each round we are allowed to askn binary comparisons. We show that log^* n+O(1) rounds are both necessary and sufficient in the best algorithm for this problem.Research supported in part by Allon Fellowship, by a Bat Sheva de Rothschild grant and by the Fund for Basic Research administered by the Israel Academy of Sciences.     

Studies on photocatalytic performance and photodegradation kinetics of zinc oxide nanoparticles prepared by microwave-assisted sol–gel technique using ethylene glycol

ZnO nanoparticles with an average particle size of 27 nm were fabricated using a microwave-assisted sol–gel method in the presence of ethylene glycol. The nanoparticles were characterized by X-ray diffraction, Monshi’s equation, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The band gap energy of the nanoparticles was measured to be 3.27 eV by UV–Vis absorption and reflection spectroscopy. Photocatalytic activity of the synthesized nanoparticles was assessed by degrading nitrophenol in aqueous solution under UV-C irradiation. The effects of initial nitrophenol concentration, amount of photocatalyst, and of pH on the photodegradation process were investigated. Degradation samples were analyzed by UV–Vis spectroscopy. Nitrophenol was removed by 98 % within 240 min. The degradation kinetics were studied and fitted well to pseudo-first-order and Langmuir–Hinshelwood models.     

Titanium Dioxide/Multi-walled Carbon Nanotubes Composite Modified Pencil Graphite Sensor for Sensitive Voltammetric Determination of Propranolol in Real Samples

A very effective electrochemical sensor for the analysis of propranolol was constructed using TiO₂/MWCNT film deposited on the pencil graphite electrode as modifier. The modified electrode represented excellent electrochemical properties such as fast response, high sensitivity and low detection limit. The proposed sensor showed an excellent selective response to propranolol in the presence of foreign species and other drugs. The electrochemical features of the modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) technique which indicated a decrease in resistance of the modified electrode versus bare PGE and MWCNT/PGE. The surface morphology for the modified electrode was determined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). Differential pulse technique (DPV) was used to determine propranolol which showed a good analytical response in the linear range of 8.5×10⁻⁸-6.5×10⁻⁶ M with a limit of detection 2.1×10⁻⁸ M. The TiO₂/MWCNT/PGE sensor was conveniently applied for the measurement of propranolol in biological and pharmaceutical media.