Oxidative polymerization of anilinium 5-sulfosalicylate with peroxydisulfate in water

Anilinium 5-sulfosalicylate was prepared and characterized by elemental analysis, and FTIR and NMR spectroscopies. It was polymerized in an aqueous solution using ammonium peroxydisulfate as an oxidant. The precipitated polyaniline 5-sulfosalicylate exhibited high thermal stability and conductivity of 0.13 S cm⁻¹. Its mass-average molar mass and polydispersity index were determined by gel-permeation chromatography as 22,900 g mol⁻¹ and 2.7, respectively. Elemental analysis and FTIR spectroscopy study of polyaniline 5-sulfosalicylate revealed the doping level and the oxidation state between emeraldine and protoemeraldine salt while corresponding studies of the polyaniline base indicate a small extent of the covalent bonding of 5-sulfosalicylate anions to polyaniline chains.     

Optical pumping of the Zeeman components in the rubidium vapor

We investigated the optical pumping of the Zeeman components of rubidium atoms, in the presence of the external magnetic field ranging from the geomagnetic up to 130 Gauss. Using the saturated absorption spectroscopy with linearly polarized pump and probe laser beams, the rubidium Doppler-free spectra at different magnetic field strengths were measured. The dips (negative intensity signals) in the saturated absorption spectra of the ⁸⁷Rb hyperfine transition lines were observed. They come as a result of the alignment process induced by the incoherent population transfer due to the hyperfine optical pumping. By inspection of the dips for different magnetic field strengths we were able to conclude about the dynamics of the alignment process in the external magnetic field. Present work is a part of the investigations concerning the influence of the magnetic field on the velocity selective optical pumping of the rubidium atoms induced by femtosecond frequency comb [D. Aumiler, T. Ban, H. Skenderovi?, G. Pichler, Phys. Rev. Lett. 95 (2005) 233001; T. Ban, D. Aumiler, H. Skenderovi?, G. Pichler, Phys. Rev. A 73 (2006) 043407].     

Direct measurement of the lifetime of optical phonons in single-walled carbon nanotubes

Time-resolved anti-Stokes Raman spectroscopy has been applied to probe the dynamics of optical phonons created in single-walled carbon nanotubes by femtosecond laser excitation. From measurement of the decay of the anti-Stokes Raman signal in semiconducting nanotubes of (6,5) chiral index, a room-temperature lifetime for G-mode phonons of 1.1+/-0.2 ps has been determined. This lifetime, which reflects the anharmonic coupling of the G-mode phonons to lower-frequency phonons, is important in assessing the role of nonequilibrium phonon populations in high-field transport phenomena.     

RAPID RESPONSES TO LIGHT AND GIBBERELLIC ACID IN ETIOLATED PEA STEMS

Abstract— An angular position sensing transducer has been used to investigate the effect of light and gibberellins on rapid growth responses in decapitated, dark-grown pea stems. The immediate effect of 3 min of red (657 nm) light was a decrease in growth rate. Short wavelength far red light (728 nm) did not reverse the effect of red. Long wavelength far red (742 nm) reversed the inhibition only during the first 30 min. Gibberellic acid induced a rapid, transient increase in growth rate in dark-grown and in red-light-irradiated plants. The length of the latent period in response to GA, was shorter in irradiated plants     

Recovery of Phenolic Acid and Enzyme Production from Corn Silage Biologically Treated by <Emphasis Type="Italic">Trametes versicolor</Emphasis>

Corn silage is used as high-energy forage for dairy cows and more recently for biogas production in a process of anaerobic co-digestion with cow manure. In this work, fresh corn silage after the harvest was used as a substrate in solid-state fermentations with T. versicolor with the aim of phenolic acid recovery and enzyme (laccase and manganese peroxidase) production. During 20 days of fermentation, 10.4-, 3.4-, 3.0-, and 1.8-fold increments in extraction yield of syringic acid, vanillic acid, p-hydroxybenzoic acid, and caffeic acid, respectively, were reached when compared to biologically untreated corn silage. Maximal laccase activity was gained on the 4th day of fermentation (V.A. = 180.2 U/dm³), and manganese peroxidase activity was obtained after the 3rd day of fermentation (V.A. = 30.1 U/dm³). The addition of copper(II) sulfate as inducer during solid state fermentation resulted in 8.5- and 7-fold enhancement of laccase and manganese peroxidase activities, respectively. Furthermore, the influence of pH and temperature on enzyme activities was investigated. Maximal activity of laccase was obtained at T = 50 °C and pH = 3.0, while manganese peroxidase is active at temperature range T = 45–70 °C with the maximal activity at pH = 4.5.     

Determination of diclofenac sodium in commercial pharmaceutical formulations and human control serum using a kinetic-spectrophotometric method

A kinetic method for the determination of micro quantities of diclofenac sodium (DS) is described in this paper. The method is based on a ligand-exchange reaction. The reaction was followed spectrophotometrically by monitoring the rate of appearance of the cobalt diclofenac complex at 376 nm. The optimum operating conditions regarding reagent concentrations and temperature were established. The optimized conditions yielded a theoretical detection limit of 1.29 microg ml(-1) based on the 3S(b) criterion. The interference effects of certain drugs, foreign ions and amino acids upon the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied to the rapid determination of diclofenac sodium in commercial pharmaceutical preparations and human control serum. The unique features of this procedure are that determination can be carried out at room temperature and the analysis time is short. The newly developed method is simple, inexpensive, and efficient for use in the analysis of a large number of samples.     

Diverse coordination of two ligands in ferromagnetic [Cu(μ-HCO2)2(3-pyOH)]n and [Cu2(μ-HCO2)2(μ-3-pyOH)2(3-pyOH)2(HCO2)2]n

Two novel polynuclear complexes with methanoate anions and 3-hydroxypyridine ligands [Cu(μ-HCO₂)₂(3-pyOH)]_n (1) and [Cu₂(μ-HCO₂)₂(μ-3-pyOH)₂(3-pyOH)₂(HCO₂)₂]_n (2), respectively, were synthesized and characterized. The central copper atom in 1 is surrounded by four methanoates and a 3-pyOH molecule, forming a square-pyramidal CuO₃NO chromophore. All the methanoates are bidentate and serve as bridges between the adjacent copper ions via syn-anti and anti–anti coordination. The basal square coordination axes are formed by O(syn), N(3-pyOH) (1.974(2), 2.016(2) Å) and O(anti), O(anti) (1.945(2), 1.960(2) Å), while the third O(anti) (2.247(2) Å) is on the top of the pyramid. A ferromagnetic transition with an exchange constant 2J/k_B = 9.2 cm⁻¹ is found for 1 below 20 K. This interaction probably takes place through two syn-anti methanoates extended in a chain through the 2D structure. On the other hand, two monoatomic Cu–O–Cu intra-dinuclear asymmetric (1.986(2), 2.415(2) Å) bridges of two methanoates in [Cu₂(HCO₂)₄(3-pyOH)₄] (2) are present. An elongated distorted octahedral coordination sphere around each copper(II) atom is completed by an additional monodentate terminal methanoate (1.975(2) Å), two N-coordinated 3-pyOH (2.005(2), 2.002(2) Å) and the third weakly O-coordinated 3-pyOH (2.732(2) Å). Although a shorter Cu?Cu distance is noticed in 2 than in 1 (4.690(1) Å 1, 3.442(1) Å 2), much weaker ferromagnetism is found in 2.     

Microcalorimetric Compatibility Testing of the Constituents of Combustible Materials and Casting Composite Explosives

The method of microcalorimetric compatibility testing of the constituents of combustible materials and casting composite explosives is based on the change in power when separately measuring the different materials involved, and their mixture, during isothermal treatment. The experimental power-time curve for the mixture was compared to the hypothetical curve constructed from the results of the measurements of individual materials. This revised version was published online in July 2006 with corrections to the Cover Date.     

Activity of acetamide in acetamide-calcium nitrate melt solutions

Activity coefficients of acetamide in acetamide-calcium nitrate melt solutions were determined from cryoscopic data in the concentration range O to 0.151 mole fraction of calcium nitrate. Enthalpies of melting and melting point depressions were obtained from DSC measurements. Melt solutions were obtained from two crystalline forms of acetamide. Eutectic formation was observed in both crystalline forms. Heat capacity of pure acetamide in the two forms was measured in the temperature range 20 to 100°C. Activity coefficients obtained for molten acetamide from two sets of cryoscopic data were in good agreement. Change of activity coefficients with calcium nitrate concentration indicate strong association between solvent and solute and water-like acting of molten acetamide.