Odd-Excited Binomial States of the Radiation Field and Some of Their Statistical Properties

In this paper a new state called odd-excited binomial state (OEBS) is introduced. It interpolates between the odd number state and the odd-excited coherent state. We discuss some statistical properties, such as the Glauber second-order correlation function and squeezing phenomenon (normal and amplitude-squared squeezing) for this state. The quasiprobability distribution functions (Husimi Q-function and Wigner W-function) are also examined.     

Quantum Properties of Odd Excited Negative Binomial States of the Radiation Field

The odd excited negative binomial states are introduced using the photon creation operator by repeated application on negative binomialstates. These states interpolate between the odd displaced Fock states and the odd excited pure thermal states. In this paper both squeezing phenomena (normal squeezing and amplitude squared squeezing) are discussed. Besides discussion of the Glauber second-order correlation function, investigations are carried out for the quasi-probability distribution functions (Wigner function and Q-function). Finally the Pegg-Barnett phase probability distribution is computed for these states.     

Synthesis,characterization, X-ray structural analysis and study of oxidative properties of propyltriphenylphosphonium bromochromate

The complex of propyltriphenylphosphonium bromochromate(VI), PrPh₃P[CrO₃Br] is easily synthesized in nearly quantitative yield using a direct reaction of chromium(VI) oxide and propyltriphenylphosphonium bromide. This compound is a versatile reagent for the efficient and selective oxidation of organic substrates, in particular for alcohols to their corresponding aldehydes or ketones, under mild conditions. This compound was characterized by IR, UV/Visible, ¹³C-n.m.r. and ¹H-n.m.r. techniques. It crystallized in the monoclinic form and its crystal and molecular structure have been determined by X-ray crystallography.     

Multigrid solution of the Poisson—Boltzmann equation

A multigrid method is presented for the numerical solution of the linearized Poisson–Boltzmann equation arising in molecular biophysics. The equation is discretized with the finite volume method, and the numerical solution of the discrete equations is accomplished with multiple grid techniques originally developed for twodimensional interface problems occurring in reactor physics. A detailed analysis of the resulting method is presented for several computer architectures, including comparisons to diagonally scaled CG, ICCG, vectorized ICCG and MICCG, and to SOR provided with an optimal relaxation parameter. Our results indicate that the multigrid method is superior to the preconditioned CG methods and SOR and that the advantage of multigrid grows with the problem size. © 1993 John Wiley & Sons, Inc.     

New methods for determination of cinnarizine in mixture with piracetam by spectrodensitometry, spectrophotometry, and liquid chromatography

Four new methods were developed and validated for the determination of cinnarizine HCl in its binary mixture with piracetam in pure and pharmaceutical preparations. The first one was a densitometric analysis that provides a simple and rapid method for the separation and quantification of cinnarizine HCI. The method depends on the quantitative densitometric evaluation of thin-layer chromatograms of cinnarizine HCI at 252 nm over concentration range of 1-6 microg/spot, with a mean accuracy of 100.05 +/- 0.91%. The second method was determination of the drug using a colorimetric method that utilizes the reaction of 3-methyl-benzothiazolin-2-one in the presence of FeCl3 as an oxidant. The green color of the resulting product was measured at 630 nm over concentration range 10-40 microg/mL, with a mean accuracy of 100.10 +/- 1.13%. The third method was a direct spectrophotometric determination of cinnarizine HCI at 252 nm over the concentration range 7-20 microg/mL, while piracetam was determined by derivative ratio spectrophotometry at 221.6 nm over concentration range 5-30 microg/mL, with a mean accuracy of 100.14 +/- 0.79 and 100.26 +/- 1.24% for cinnarizine HCI and piracetam, respectively. The last method was a liquid chromatography analysis of both cinnarizine HCI and piracetam, depending on quantitative evaluation of chromatograms of cinnarizine HCI and piracetam at 252 and 212 nm, respectively, over the concentration range 10-200 microg/mL for cinnarizine HCI and 20-500 microg/mL for piracetam, with a mean accuracy of 100.03 +/- 0.89 and 100.40 +/- 0.94% for cinnarizine HCI and piracetam, respectively. The proposed procedures were checked using laboratory-prepared mixtures and successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed procedures was further assessed by applying the standard addition technique. Recoveries were quantitative, and the results obtained agreed with those obtained by other reported methods.     

60]- and [70]Fullerenes are trifluoromethylated across 5:6-bonds

Trifluoromethylation of [60]- and [70]fullerenes occurs across both 6:6- and 5:6-bonds giving unsymmetrical tetramethyl adducts having four contiguous CF3 groups; both fullerenes give bis adducts which do not involve 6:6-addition, and unsymmetrical hexa-adducts (with contiguous CF3 groups) are also obtained from [60]fullerene.     

Electroanalysis with tungsten electrodes : I. The tungsten/platinum bimetallic pair in potentiometry at zero current

The W/Pt bimetallic pair has been applied in various potentiometric titrations. Except for the neutralization of dicarboxylic acids, e.g., oxalic, the pair is suitable for neutralization titrations where ΔE/ΔV values at the equivalence point are higher on W than on Pt. Tungsten oxides increase the inflexion pd. The pair is also suitable for oxidation/reduction titrations using permanganate, dichromate, and ceric sulfate, and for precipitation reactions with silver nitrate. However, it gives a small inflexion pd in the oxidation of thiosulfate by iodine. EDTA titrations of copper, magnesium, and calcium give a sharp inflexion in the case of copper only. This pair may be useful in routine analyses requiring a robust electrode assembly but not a high degree of accuracy.     

The racemization of an optically active sulfilimine and optically active aminosulfonium salts

The racemization of an optically active sulfilimine and optically active aminosulfonium salts was kinetically measured. The mechanism of the racemization of optically active sulfilimine (?)-1 has been established. The activation parameters for the racemization of (?)-1 and (?)-7 were calculated. A plausible pathway for the decomposition of (?)-6, (?)-7 and (?)-8 with tetra-n-butylammonium bromide in the presence of methyl ethyl ketone to provide 3-p-tolylthio-2-butanone 22 is proposed.     

Europium-sensitized luminescence determination of oxytetracycline in catfish muscle

An europium-sensitized time-resolved luminescence (TRL) method was developed to determine oxytetracycline (OTC) in cultivated catfish muscle. Extraction of OTC from fish muscle was performed with pH 4.0 ethylenediaminetetraacetic acid (EDTA)-McIlvaine buffer and clean up with hydrophilic-lipophilic balanced copolymer solid phase extraction (SPE) cartridges. The eluate was used without further concentration for TRL measurement in pH 9.0 micellar tris(hydroxylmethyl)aminomethane (TRIS) buffer. Cetyltrimethylammonium chloride (CTACl) was used as surfactant and EDTA as a co-ligand. The excitation and emission wavelengths were set at 388 and 615 nm, respectively. The linear dynamic range was 0-1000 ng g⁻¹ (R²=0.9995). The recovery was 92-112% in the fortification range of 50-200 ng g⁻¹ and the limits of detection (LOD) ranged from 3 to 7 ng g⁻¹. Incurred catfish samples were used to demonstrate the performance of the method around 100 ng g⁻¹, the European Union maximum residue level.     

Perdeuterated Conjugated Polymers for Ultralow‐Frequency Magnetic Resonance of OLEDs

The formation of excitons in OLEDs is spin dependent and can be controlled by electron‐paramagnetic resonance, affecting device resistance and electroluminescence yield. We explore electrically detected magnetic resonance in the regime of very low magnetic fields (<1 mT). A pronounced feature emerges at zero field in addition to the conventional spin‐ Zeeman resonance for which the Larmor frequency matches that of the incident radiation. By comparing a conventional π‐conjugated polymer as the active material to a perdeuterated analogue, we demonstrate the interplay between the zero‐field feature and local hyperfine fields. The zero‐field peak results from a quasistatic magnetic‐field effect of the RF radiation for periods comparable to the carrier‐pair lifetime. Zeeman resonances are resolved down to 3.2 MHz, approximately twice the Larmor frequency of an electron in Earth's field. However, since reducing hyperfine fields sharpens the Zeeman peak at the cost of an increased zero‐field peak, we suggest that this result may constitute a fundamental low‐field limit of magnetic resonance in carrier‐pair‐based systems. OLEDs offer an alternative solid‐state platform to investigate the radical‐pair mechanism of magnetic‐field effects in photochemical reactions, allowing models of biological magnetoreception to be tested by measuring spin decoherence directly in the time domain by pulsed experiments.