Anode slime behaviour in a laboratory-scale copper electrorefining process

Combining conventional electrochemical measurements, laser-based visualization and digital image processing, the movement of anode slime, its spatial distribution and path of falling during the copper electrorefining process were investigated in a laboratory scale cell. Two types of anode slime, small agglomerates and fine particles were observed. The behaviour of the slime was found to be closely related to the electrolyte circulation pattern. Different circulation rates and direction can only change the magnitude of the falling rate of small agglomerates, but not its direction. The path of falling is essentially random. By contrast, the direction of circulation can change both the rate of movement and the direction in the case of fine-particle slimes. Downward circulation accelerates the rate of settling; the higher the circulation rate, the faster the rate of slime removal from the cell     

Hydrosilylation and dehydrocondensation reactions of methylhydridesiloxane to acrylic and methacrylic acids

The hydrosilylation of α,ω‐bis(trimethylsiloxy) methylhydridesiloxane (degree of polymerization ≈ 53) with acrylic and methacrylic acid with various ratios of the initial compounds, in the presence of platinum hydrochloric acid, has been investigated. In the presence of platinum hydrochloric acid, competitive dehydrocondensation reactions take place with the formation of various oligomers with various chemical links. In the later stages of the reaction, three‐dimensional systems have been obtained. During dehydrocondensation, the reaction order, reaction rate constants, and activation energy have been determined. The structures of the synthesized oligomers have been determined with IR and NMR spectroscopy data. Gel permeation chromatography, differential scanning calorimetry, and X‐ray analyses of the synthesized oligomers have been carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3243–3252, 2007     

Electropolymerization of chlorinated phenols on a Pt electrode in alkaline solution. Part II: An electrochemical quartz crystal microbalance study

Electropolymerization of phenol and mono-, di-, tri-, pentachlorophenols was studied using EQCM on a Pt electrode at 0.78 V (SHE) in 1 M NaOH solution containing 0.1 M of the corresponding phenol. The highest electropolymerization rate was found for ortho-substituted chlorophenols indicating a weak fouling of the electrode. Low electropolymerization rates for para-substituted chlorophenols suggest a low permeability of the polymer film, resulting in rapid electrode fouling. The EQCM data suggest that electropolymerization of chlorophenols occurs without Cl-elimination for the monomers with unsubstituted ortho and para positions. Dechlorination is most pronounced for electropolymerization of para-substituted isomers. The mechanism of electropolymerization of chlorophenols is discussed.     

The transfer matrix method for lattice proteins—an application with cooperative interactions

The transfer matrix method for generating lattice conformations of proteins is explained and applied to lattice proteins having high-level cooperativity to represent hydrophobic interactions. The main advantage of the method is the extremely efficient attrition-free generation and enumeration of compact conformations. We review the application of the method for the generation and complete, exact enumeration of all conformation for linear and cyclic chains in 2D on the square lattice and in 3D on the cubic lattice. We show for compact conformations that the growth of the chain in a piecewise way, cross-section by cross-section, is much more efficient than the traditional linear chain growth. We discuss an extension of the method by including information about the amino acid sequence. We develop a Zimm-Bragg [J Chem Phys 31 (1959) 476-85]-like theory of hydrophobic cluster formation by using the transfer matrix method. We show that the transfer matrix approach to the generation and averaging over chain conformations can be formulated as an algebraic problem. We show also how the transfer matrix method can be extended to off-lattice proteins.     

Laryngeal mucosal changes experimentally produced by endogenous and exogenous factors in mice (author's transl)]

Experimentally an attempt was made to demonstrate the effects of exogenous factors on the hormonally altered laryngeal mucosa of mice. Albany mice were divided into 4 groups of 8. In the first group of males, testosterone was injected daily; in the second group of males, no testosterone was given; in the third group of females with previously removed ovaries, testosterone was given daily; and, in the fourth group of females, no testosterone was given. All 4 groups were exposed to cigarette smoke for one hour daily for six weeks. Histopathological examination of the mucosa showed that the larynx can be considered a "target" organ for male hormones and that exogenous factors produce changes that lead to malignancy.     

A study of ergonomics factors in washbasin design

A 4-week UNESCO-sponsored mission to the Department of Architecture, Karadeniz Technical University in Eastern Turkey, gave an opportunity to apply ergonomics techniques to some aspects of that country's domestic washbasin design. The study was intended to provide experience in questionnaire design and administration, in the application of psycho-physical methods, and to highlight the importance of determining user characteristics and preferences with regard to the built environment. A field study elicited information on dimensions and positioning of existing wash-basins and ancillary equipment and the opinions of users as to the suitability of these features in relation to the activities performed. A laboratory study, using an adjustable rig permitting variation in the heights of basin, taps and mirror/shelf, followed. The data obtained on preferred heights of these items led to the conclusions that basin height should be increased to between 95 and 100 cm to satisfy the majority of users; tap height above the basin should be reduced to about 11 cm; the shelf and lower edge of a mirror sited above the basin should be 136 cm above the floor; and a clear space of 110 cm should be available between the front of the basin and a wall or other obstruction. Suggestions on other design aspects of the bathroom, resulting from the study, are discussed.     

Carbon Nanofibers: A New Ultrahigh-Strength Material for Chemical Technology

Carbon nanofibers are described as a new ultrahigh-strength material, which is superior to both ordinary carbon fibers and other high-strength materials. The place occupied by nanofibers in the classification of carbon materials is shown, and an analysis is made of the relationship between the structure of a fiber and its useful properties, in particular, the strength and tensile modulus. Studies on the synthesis of nanofibers are reviewed. It is shown that the practically important problem of producing nanofibers of maximum possible length must be solved by controlling the temperature conditions of the reaction. The prospects for introducing nanofibers into the market of high-strength and heat-resistant materials are analyzed. The most likely prospect seems to be the partial replacement of polyacrylonitrile-based fibers by nanofibers, first and foremost, in the fields where the requirements for high strength are particularly stringent due to safety reasons.     

Azo disperse dyes with polyfluoroalkyl groups attached to the nitrogen atom of the coupling component

A number of new azo disperse dyes with polyfluoroalkyl groups attached to the nitrogen atom of the coupling component have been prepared. The influence of polyfluoroalkyl groups on the colour and properties of azo dyes has been studied. The replacement of hydrogen atoms of the methyl group of the coupling component by polyfluoroalkyl radicals causes a hypsochromic shift of absorption maximum in a neutral solution and deepening of the dye colour in an acid solution. All tested dyes showed a high lightfastness on acetate and polyamide fibres.     

Electrocapillary elements. III. Properties and applications to variable pressure manometers

The characteristics of electrocapillary elements with their filling subjected to vibrations by mechanical and electrical harmonic input signals of frequencies in the range 0.003–30 Hz as well by voltage or pressure jump were studied. The idea of variable pressure or pressure jump measurement by means of an electrocapillary transducer and a model of such a manometer are presented.