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The introduction of room temperature continuous wave external-cavity quantum cascade lasers (EC-QCLs) with narrow linewidths has greatly facilitated high resolution spectroscopy over wide spectral ranges in the mid-infrared (MIR) region. Using the wide tuning range of an EC-QCL we have measured the absolute line strengths of many P-branch transitions of the stretching dyad of the ν 3 fundamental band of 28 SiH 4 between 2096 and 2178 cm −1 . Furthermore, the high spectral resolution available has enabled us to resolve and measure representative examples of the tetrahedral splittings associated with each component of the P-branch. The positions of these components are in excellent agreement with spherical top data system (STDS) predictions and theoretical transitions from the TDS spectroscopic database for spherical top molecules. These are the first measurements of these line strengths of 28 SiH 4 and are an example of the applicability of high-powered, widely tunable EC-QCLs to high resolution spectroscopy. [ABSTRACT FROM AUTHOR]

The wall de-excitation probability of vibrationally excited nitrogen molecules was determined using infrared (IR) titration with CO, CO2 and N2O. Gas mixtures of N2 with 0.05–0.5% of CO (CO2 or N2O) were excited by a pulsed dc discharge at p = 133 Pa in a cylindrical discharge tube. During the afterglow, the vibrational relaxation of titrating molecules was monitored in situ with quantum cascade laser absorption spectroscopy. The value of was deduced from measured vibrational relaxation times using a model of vibrational kinetics in N2. It was found that adsorption of IR tracers on the surface may increase the value of by a factor up to two, depending on the molecule and the surface material. It was demonstrated that N2O is the most inert and reliable tracer and it was used for the determination of on silica, Pyrex, TiO2, Al2O3 and anodized aluminum. Pretreatment of the silica surface by low-pressure plasma was found to have a strong effect on the vibrational de-excitation. Values of measured after O2, Ar and N2 plasma pretreatment of the same silica discharge tube were 5.7 × 10−4, 8.2 × 10−4 and 11 × 10−4, respectively. This study clearly demonstrates that the presence of adsorbed atoms and molecules on the surface may significantly alter the value of . [ABSTRACT FROM AUTHOR]

The objective of this study is to understand fundamental aspects of interactions of plasmas with catalytic surfaces. Based on this approach the reactivity of plasma treated and stimulated catalytic surfaces of TiO2 is studied by analysing the oxidation (i) of C2H2 to CO and CO2 and (ii) of CO to CO2. The inner surface of a Pyrex discharge tube is coated with TiO2 films impregnated with TiO2 nanoparticles, which provides a surface area of about 4m². In addition to the exposure of the TiO2 surface by low-pressure radio-frequency plasmas using O2, Ar or N2 (f = 13.56 MHz, p = 0.53 mbar, P = 17 W) the surfaces are stimulated by heating and UV radiation treatment. The temporal development of the concentrations of the precursor gases C2H2 or CO and of the reaction products is monitored using quantum cascade laser absorption spectroscopy, which provides multi-component detection in the mid-infrared spectral range. The C2H2 concentration was found to be nearly constant over time after a pre-treatment with Ar or N2 discharges using an initial gas mixture of 1% C2H2 in Ar. However, a strong decay of the concentration of C2H2 is observed for pure O2 plasma pre-treatment. In general, the decay is found to be nearly exponential with time constant in the order of about 10 min. The reactive adsorption of C2H2 molecules on the inner surface of the tube reactor showed a density of about 7.5 × 1012 C2H2 molecules cm-2. This behaviour demonstrates that the reaction (Oads +C2H2)TiO2 produces some adsorbed intermediates, which can be thermally or photo-catalytically oxidized to CO2. In contrast, when 1% CO in Ar is used as an initial gas mixture no adsorption processes on the TiO2 surface could be detected. An effective destruction of CO took part via photo-catalytic oxidation. [ABSTRACT FROM AUTHOR]

In Ar and Ar/N2 RF plasmas with admixtures of aluminum tri-isopropoxide (ATI) the fragmentation of this metal-organic precursor has been studied by means of infrared absorption spectroscopy (IR-AS) using an external-cavity quantum cascade laser (EC-QCL) arrangement. The experiments were performed in an asymmetric capacitively coupled reactor at a frequency of f = 13.56 MHz and a pressure of up to p = 10 Pa. The discharge power was in the range of P = 40 - 100 W. Using EC-QCLAS the evolution of the concentrations of six stable molecules, CH4, C2H2, C2H4, H2O, HCN and HNO3, has been monitored in the plasma. The concentrations of these plasma chemical products were found to be in the range of about 7 × 1012 - 2 × 1014 molecules cm-3 (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The synthesis of L-ornithine L-aspartate that involved basic hydrolysis of L-arginine by barium hydroxide, precipitation of barium cations as barium carbonate, addition of L-aspartic acid, and direct precipitation of L-ornithine L-aspartate was described. The obtained compound could be used as a hepatoprotective drug. [ABSTRACT FROM AUTHOR]

N-acetyl derivatives of L-glutamine, L-proline, and 4-hydroxy-L-proline were synthesized in aqueous solutions with acetic anhydride as the acetylating agent. The resulting compounds were used as medicinal substances. [ABSTRACT FROM AUTHOR]

Taurine (2-aminoethanesulfonic acid) has been synthesized via reaction of 2-aminoethylsulfuric acid (prepared from monoethanolamine and sulfuric acid) with sodium sulfite. The target compound was separated from the excess of sodium sulfite by extraction with conc. aqueous ammonia (25%). [ABSTRACT FROM AUTHOR]

A series of selenium-containing complex salts of L-lysine and L-arginine has been synthesized. Some physicochemical characteristics of selenium-containing amino acids are reported. [ABSTRACT FROM AUTHOR]

The synthesis of iron(II) di- DL-aspartate is described. Tests on rabbits with a model of acute and chronic anemia showed that the administration of the synthesized compound led to an increase in the hemoglobin level and in the numbers of erythrocytes and thrombocytes. [ABSTRACT FROM AUTHOR]

In Ar and He radio-frequency (RF) plasmas with admixtures of C2H2 and CH4 the hydrocarbon chemistry has been studied in relation to dust particle formation by means of infrared tunable diode laser absorption spectroscopy (TDLAS) combined with Fourier transform infrared (FTIR) spectroscopy. The experiments were performed in a RF capacitively coupled parallel plate reactor at a frequency of f = 13.56 MHz, a pressure of p = 0.1 mbar and a flow rate of Φ = 8 sccm of Ar or He with admixtures of 0.5 sccm C2H2 or 1 sccm CH4. The power was P = 15 W. Using TDLAS, the temporal evolution of the concentrations of the methyl radical and of four stable molecules, C2H2, CH4, C2H4 and CO, was monitored in the plasma. Simultaneously, the growth process of the dust particles was analysed by FTIR spectroscopy. The degree of dissociation of the acetylene precursor was found to be nearly constant in the range of 96% under stabilized conditions for both the Ar and He plasmas. In contrast, the degree of dissociation of the methane precursor varied between 45% and 90% depending (i) on the appearance of dust particles in the reactor volume and (ii) on the Ar or He plasma conditions. The methyl radical concentration was found to be in the range of 1011 molecules cm−3. The concentrations of all hydrocarbon species were strongly correlated with the dynamic of the dust formation. Fragmentation efficiencies of acetylene (RF (C2 H2) = 3.2 × 1016 molecules J−1) and of methane (RF (CH4) = (0.16–2.5) × 1016 molecules J−1) and conversion efficiencies to the produced hydrocarbons (RC = (0.23–8.5) × 1014 molecules J−1) could be estimated in dependence on the discharge conditions in the RF plasma. [ABSTRACT FROM AUTHOR]

A new method for determination of the wall de-excitation probability of vibrationally excited N2 on different surfaces exposed to low-pressure plasmas has been developed. A short dc discharge pulse of only a few milliseconds was applied to a mixture containing 0.05–1% of CO2 in N2 at a pressure of 133 Pa. Due to a nearly resonant fast vibrational transfer between N2(v) and the asymmetric ν3 mode of CO2 the vibrational excitation of these titrating molecules is an image of the degree of vibrational excitation of N2. In the afterglow, the vibrational relaxation of CO2 was monitored in situ using quantum cascade laser absorption spectroscopy. The experimental results were interpreted in terms of a numerical model of non-equilibrium vibrational kinetics in CO2–N2 mixtures. Heterogeneous relaxation was the main quenching process of N2(v) under the conditions of this study, which allowed determination of the value of from the best agreement between the experiment and the model. The new method is suitable for determination in a single plasma pulse with the discharge tube surface pretreated by a low-pressure plasma. The relaxation probability of the first vibrational level of nitrogen γ1 = (1.1 ± 0.15) × 10−3 found for Pyrex and silica is in reasonable agreement with the literature data. Using the new technique the N2(v = 1) quenching probability was measured on TiO2 surface, γ1 = (9 ± 1) × 10−3. A linear enhancement of the N2(v) wall deactivation probability with an increase in the admixture of CO2 was observed for all studied materials. In order to explain this effect, a vibrational energy transfer mechanism between N2(v) and adsorbed CO2 is proposed. [ABSTRACT FROM AUTHOR]

A method for the "Dissolution" test was developed and validated for tablets of the new bisphosphonate sodium prodronate and was compliant with the general normative requirements. Dissolution was carried out on an instrument with paddles rotating at a rate of 50 rpm. The quantity of drug entering solution over 45 min was assed by UV spectrophotometry via formation of complexes with copper ions, with an absorption peak at 237 nm. [ABSTRACT FROM AUTHOR]

A spectrophotometric method for determining sodium prodronate in tablets by measuring the absorption at 237 ± 2 nm of a Cu(II)—prodronate complex in acetate buffer was developed and validated. The method met applicable requirements of the SP RB for quantitative analysis methods for drugs and could be recommended for use by the State Drug Quality Control Inspection and technical control departments of chemical and pharmaceutical plants. [ABSTRACT FROM AUTHOR]

Abstract: The active screen (AS) nitriding is an advanced technology for the plasma nitriding of steel components providing a number of advantages over conventional plasma nitriding. Developed in the last decade, the AS technology has found its industrial application, however the understanding of the fundamental mechanisms and their relationship is not complete. For the first time the mid infrared tunable diode laser absorption technique in combination with the quadruple mass spectrometry has been applied in this work. In-situ diagnostics of chemical phenomena in the N2–H2 plasmas under variation of the process conditions such as H2 to N2 gas ratio, process temperature and bias activation power provided valuable information about the concentration of active nitrogen species in the vicinity of the samples'' surfaces. The thickness of the compound layer representing the nitriding efficiency was used as a response to nitriding conditions for the evaluation of selected process parameters derived from the plasma diagnostic studies. A 1:1 gas mixture of the N2–H2 process gases seems to be most effective to get thick compound layers. [Copyright &y& Elsevier]

We synthesized chalcopyrite (CuFeS2) nanoparticles by methods involving laser ablation and electrical discharge in water. The nanoparticles obtained were exposed to an oxygen/argon plasma of a microwave discharge. The synthesized material was studied by photometry, x-ray diffraction (XRD), and energy dispersive x-ray elemental analysis (EDX), IR spectroscopy, and atomic force electron microscopy (AFM). We have established that the nanoparticles are morphologically stable relative to exposure to plasma fluxes of power ≤1 kW, and can be used as a model system to study processes of interaction between a plasma and minerals. [ABSTRACT FROM AUTHOR]