Phenomenological J-plane singularities of amplitudes at T = 0

The Mellin transforms of the imaginary parts of the πN forward amplitudes are computed from the experimental total cross sections. An analytic continuation of these transforms is performed to determine the phenomenological J-plane singularities at t = 0. The continuation supports the J-plane analyticity assumption in the case I = 0. A generalization of the method to non-forward t-values is indicated. The effective Regge cut is found to be small in I = 1 amplitudes.     

Reductive coprecipitation as a separation method for the determination of gold,palladium, platinum,rhodium, silver,selenium and tellurium in geological samples by graphite furnace atomic absorption spectrometry

A method for the separation of Au, Pd, Pt, Rh, Ag, Te and Se from geological samples at trace levels is presented. The elements are separated from the matrix after dissolution by reductive coprecipitation using mercury as a collector and tin(II) chloride as a reductant. The efficiency of coprecipitation is studied by varying the acidity of the solutions and the amount of collector. The analyte elements are determined by graphite furnace atomic absorption spectrometry. In the determination of volatile elements (Te, Au and Ag), matrix modification with iridium is used. Selenium is determined with a mixed matrix modifier containing ascorbic acid and iridium. The method is tested by analysing geochemical reference samples.     

A Cheap One-Pot Approach to Tetraethyl Methylenediphosphonate

A cheap procedure for the preparation of tetraethyl methylene-diphosphonate is described.     

Combined synthesis and in situ coating of nanoparticles in the gas phase

Ga₂O₃ was-synthesized by doping a premixed H₂/O₂/Ar flat flame with diluted trimethyl gallium Ga(CH₃)₃ in a low-pressure reactor. The mean particle diameter d _p of the resulting metal oxide was characterized in-situ with a particle mass spectrometer (PMS), and was observed to range between 2.5 nm ≤ d _p ≤ 6.5 nm. XRD results show that the as-synthesized Ga₂O₃ nanoparticles are mostly amorphous, although, a few broad reflexes were observed that indicate the presence of some degree of crystallinity. Thermal annealing of the as-synthesized material at 1000 °C for 5 min yielded β-Ga₂O₃ with a monoclinic structure. UV–VIS measurements indicate strong absorption in the UV range (4.8 eV), which corresponds quite well to the direct band gap of bulk Ga₂O₃. Photoluminescence (PL) measurements of the as-synthesized metal oxide show a broad emission ranging from 350 nm to 600 nm with a maximum at 460 nm. Crystalline β-Ga₂O₃ exhibited stronger luminescence than as-synthesized particles.     

Direct synthesis of hydrogen peroxide in microreactors

Several studies concerning direct synthesis of hydrogen peroxide in microreactors are reviewed. Several types of microreactors have been applied. Their high surface area-to-volume ratio and small internal volume improve safety, which is required when operating with explosive gases. The tested microreactors represent capillary reactors and more sophisticated reactors with a special plate structure on which reaction channels have been machined. Both single- and multi-channel arrangements have been applied. The catalysts have been installed in the reactor in the form of powder or washcoat layer on the channel wall. Palladium and platinum on various support material, such as SiO₂, Al₂O₃ and C, have been tested. Water was the most common solvent, but also methanol, ethanol, and isopropanol have been used because of their better gas dissolving properties. In addition to solvents, chemicals, often called promoters, have been utilised to improve productivity. The most typical promoters were halide ions, such as Br^? and Cl^? and inorganic acids. Hydrogen peroxide has been produced successfully by several research groups. The highest reported mass fraction of hydrogen peroxide was 5 wt %.     

Synthesis of copolymer-stabilized silver nanoparticles for coating materials

Silver ions being less toxic than silver nanoparticles, a more safe material can be obtained to be used as antimicrobial coating. This can be achieved by using thiol chemistry and covalently attach the silver nanoparticles in the coating. Our aim is to produce a coating having antimicrobial properties of silver ions but with the silver nanoparticles firmly attached in the coating. Here, we present a way to produce silver nanoparticles that can be used as a component in a coating or as such to produce an antimicrobial coating. The silver nanoparticles presented here are stabilized by a copolymer (poly(butyl acrylate–methyl methacrylate)) that is soft and has well-known good film-producing properties. The reversible addition-fragmentation chain transfer radical polymerization technique used to prepare the polymers provides conveniently a thiol group for effective binding of the silver nanoparticles to the polymers and thus to the coating.     

Simple immobilization of pyrroloquinoline quinone on few-walled carbon nanotubes

Pyrroloquinoline quinone (PQQ) was immobilized on glassy-carbon electrodes (GCE) modified with single-walled carbon nanotubes (SWCNT), few-walled carbon nanotubes (FWCNT) and carbon black (Vulcan XC72R). Modified electrodes were prepared by drop-casting. Immobilization was achieved with an extremely simple dipping procedure and without any further modification to the electrodes. Electrochemical performance of the electrodes was studied by cyclic voltammetry and spectroelectrochemistry. FWCNT adsorbed 30 times more PQQ than the other carbon materials. Compared to more complicated immobilization methods, PQQ/FWCNT/GCE showed well-defined electrochemistry in a considerably wide pH area from 2 to 12. The dipping process is affected by pH and electrostatic forces. At dipping pH 9.5, where both FWCNTs and PQQ have strong negative charge, the adsorption was halved compared to dipping pH 2, where the charges are smaller.