Powdering Lower Chromium Carbide and Nitride Phases

Powder Metallurgy and Metal Ceramics - A study has been made on the powdering capacity of the lower chromium carbide and nitride, and also chromium carbonitride. The powdering ability is dependent...     

Stabilization of the ethane oxidation catalytic activity of Cu-ZSM-5

The state of isolated copper ions in Cu-ZSM-5 containing additions of La, Ce, and Co was monitored in-situ by ESR under flow conditions. Treatment by steam at 630°C for 17 h or high-temperature dry calcination at 850°C induce an irreversible change in coordination for practically all square-planar Cu²⁺ ions in mono-cationic Cu-ZSM-5 without agglomeration or encapsulation of the isolated ions. All Cu²⁺ ions remain accessible to gas-phase molecules, but the catalytic reactivity of these altered copper sites decreases drastically. A stabilizing effect is noted for samples modified by a relatively large amount, ca. 5.0 wt.-%, of multivalent rare-earth ions La or Ce. Here a part of the copper ions (20–30%) preserves the parent square-planar Cu²⁺ state even after calcination at 850°C for 0.5 h. The effect of ca. 1% La or Ce is much less pronounced. The catalytic activity in the complete oxidation of ethane correlates well with the number of square-planar cupric cations retained by the samples after different treatments. The introduction of cobalt sharply increases the ethane oxidation activity of samples calcined at 500–650°C.     

Chiral Octahedral Complexes of Cobalt(III) as “Organic Catalysts in Disguise” for the Asymmetric Addition of a Glycine Schiff Base Ester to Activated Olefins

Stereochemically inert and positively charged chiral complexes of cobalt(III) prepared from Schiff bases derived from chiral diamines and salicylaldehydes were shown to be efficient catalysts of the benchmark asymmetric phase‐transfer Michael addition of nine activated olefins to O’Donnell’s substrate. The reaction products had enantiomeric purities of up to 96%. DFT calculations were invoked to rationalize the stereochemistry of the addition.

     

Comparative case study of diffusion of eye movement desensitization and reprocessing in two clinical settings: Empirically supported treatment status is not enough.

An in-depth comparative case study was conducted of two attempts at diffusion of an empirically supported, but controversial, psychotherapy: eye movement desensitization and reprocessing (EMDR). One Department of Veterans Affairs (VA) treatment setting in which there was substantial uptake was compared with a second VA setting in which it was not adopted. Qualitative interviews were conducted with 10 mental health clinicians at the first site, and 19 at the second. Critical selling points for EMDR were a highly regarded champion, the observability of effects with patients, and personally experiencing its effects during a role training session. Compatibility with existing psychotherapist practices and values further allowed the therapy to become embedded in the organizational culture. At the second site, a sense that EMDR was not theoretically coherent or compelling overwhelmed other considerations, including its empirical status. Comparative studies contrasting settings in which innovative therapies are implemented versus those in which they were rejected may aid in refining theories of and strategies for dissemination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationships between H2 photoproduction and different electron transport pathways in sulfur-deprived Chlamydomonas reinhardtii

In this study the relationships between photosystem (PS) II dependent and independent pathways of H₂ photoproduction, cyclic electron transport around PS I, chloro- and mitorespiration, and transmembrane ΔpH were examined by inhibitor analysis in S deprived Chlamydomonas reinhardtii. The rate of non-photochemical reduction of plastoquinones in photosynthetic membranes was significantly diminished under starvation which may explain the minor contribution of the PS II independent pathway of H₂ photoproduction in starved cells. The suppressive effect of the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea on the long-term H₂ photoproduction was shown to be entirely attributed to the inhibition of electron transport in PS II, whereas non-specific interactions did not take place. Ferredoxin-quinone reductase – dependent cyclic electron transport around PS I slowed down H₂ photoproduction more than two fold. This result was related to the competition between ferredoxin-quinone reductase and hydrogenase for the reduced ferredoxin and to the decrease in transmembrane ΔpH induced by the cyclic electron flow. The ΔpH gradient was shown to down regulate the PS II independent pathway of H₂ photoproduction in starved cells.     

Self-Organizing Approach for Automated Gene Identification

Self-training technique for automated gene recognition both in entire genomes and in unassembled ones is proposed. It is based on a simple measure (namely, the vector of frequencies of non-overlapping triplets in sliding window), and needs neither predetermined information, nor preliminary learning. The sliding window length is the only one tuning parameter. It should be chosen close to the average exon length typical to the DNA text under investigation. An essential feature of the technique proposed is preliminary visualization of the set of vectors in the subspace of the first three principal components. It was shown, the distribution of DNA sites has the bullet-like structure with one central cluster (corresponding to non-coding sites) and three or six flank ones (corresponding to protein-coding sites). The bullet-like structure itself revealed in the distribution seems to be very interesting illustration of triplet usage in DNA sequence. The method was examined on several genomes (mitochondrion of P.wickerhamii, bacteria C.crescentus and primitive eukaryot S.cerevisiae). The percentage of truly predicted nucleotides exceeds 90%.     

Fluorescence spectroelectrochemical sensor for 1-hydroxypyrene

A spectroelectrochemical sensor was demonstrated for an organic compound whose oxidation proceeds through an electron transfer-chemical reaction-electron transfer (ECE) mechanism to generate new chemical species that are used for detection by fluorescence. The polycyclic aromatic hydrocarbon 1-hydroxypyrene (1-PyOH) served as a representative model analyte. The spectroelectrochemical properties of 1-PyOH in solution were explored with an optically transparent thin layer electrode. Electrochemical oxidation of 1-PyOH under acidic conditions proceeds via the ECE mechanism to a diquinonepyrene, which shows reversible electrochemistry and fluoresces at 425 nm in its reduced form, dihydroxypyrene. The sensor consisted of a tin-doped indium optically transparent electrode coated with a Nafion thin-film (20 nm) that rapidly preconcentrated the analyte at the sensor surface. Fluorescence in the film was excited by the evanescent wave from attenuated total reflection spectroscopy. Electrochemical modulation of dihydroxypyrene fluorescence at 425 nm in the 500 to -200 mV (vs Ag/AgCl) potential range was used for indirect detection of 1-PyOH. The spectroelectrochemical sensor calibration curve had a range of 5 × 10(-9) to 1 × 10(-6) M with a calculated detection limit of 1 × 10(-9) M.     

A New Method of Producing Radionuclide-Labeled Microspheres for Radionuclide Therapy

This work is devoted to obtaining radionuclide-labeled microspheres for radionuclide therapy as a therapeutic drug with a selective method of delivery. The nature of magnetic microspheres and quantitative elemental composition radiopreparats was considered. We have developed a new method of producing radionuclide-labeled microspheres （radiopharmaceutical ^140Nd-microspheres） for radionuclide therapy.     

Microwave frequency conversion in coplanar waveguide on bilayered substrate with (Ba,Sr)TiO3 film

Abstract

Experimental and simulated spectra of microwave (30GHz) signal at the output of the coplanar waveguide (CPW) based on Ba_xSr_1-xTiO₃ film are presented and discussed. The modulation of Ba_xSr_1-xTiO₃ film dielectric constant by the application of high frequency (f ≈ 20MHz) control signal results in the generation of side frequency components in the output signal spectrum. The analysis of experimental data is performed on the basis of considering the CPW section with tunable effective dielectric constant as a phase modulator