Electrochemical oxidation of an acid dye by active chlorine generated using Ti/Sn<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Ir<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> electrodes

The generation of active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of chloride ions (0.05 mol L⁻¹) and a low current density (5 mA cm⁻²) it was possible to produce up to 60 mg L⁻¹ of active chlorine on a Ti/Sn_0.99Ir_0.01O₂ anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated with in situ electrogenerated active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4, 25 mA cm⁻² and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus time reveal a zero order reaction at dye concentrations up to 1.0 × 10⁻⁴ mol L⁻¹. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed.     

Core surveillance of liquid metal fast breeder reactors by delayed neutron signals

Concerning safe operation of LMFBRs, information is reviewed on delayed neutron signals from defective fuel pins including the results of recent investigations like: operation of KNK II with defective fuel pins, the inpile blockage experiments Mol 7C, and loop experiments with artificially defected fuel pins. The main result is that operation with cladding failures can be tolerated in principle under safety aspect, both improvements in the interpretation and comprehension of signals are required for the determination of admissible limits.     

Heat transfer characteristics of multiwall carbon nanotube suspensions (MWCNT nanofluids) in intertube falling-film flow

Multiwall carbon nanotube suspensions (MWCNT nanofluids) are used in an intertube falling-film flow to explore the nanofluid effects on heat transfer characteristics. Water-based and ethylene–glycol-based nanofluids are prepared at concentrations of 0, 0.05, 0.14 and 0.24 vol%. Thermal conductivity and viscosity of these nanofluids is measured. Falling-film heat transfer behavior of these nanofluids is also investigated and the results are compared to those of the base fluids. Based on the same liquid feeding flow rate, it is observed that the heat transfer coefficients of the water-based nanofluids decreases then increases as the MWCNT concentration increases, and the heat transfer coefficient of the ethylene–glycol-based nanofluids decreases with an increased MWCNT concentration. A model is provided for predicting the heat transfer enhancement of the nanofluids in intertube falling-film flow, and an agreement between predictions and experimental data is obtained for nanofluids with larger MWCNT concentrations. When comparing the heat transfer coefficient based on the same Reynolds number, up to 20% or higher heat transfer enhancement can be observed for ethylene–glycol based nanofluids.     

Ceramics and ceramic matrix composites for heat exchangers in advanced thermal systems—A review

In air-conditioning and energy-recovery applications, heat exchangers are very important to the overall efficiency, cost, and size of the system. Current heat exchanger designs rely heavily on fin-and-tube or plate heat exchanger designs, often constructed using copper and aluminum. Recent developments in material science—in particular, advances in ceramics and ceramic matrix composites—open opportunities for new heat exchanger designs. Some research directed toward using these materials for heat exchangers in other applications has been reported; however, there has not been a comprehensive study of the use of these emerging materials in both conventional HVAC&R systems and emerging energy technologies. This review reports the current state-of-the-art of ceramic materials for use in a variety of heat transfer systems.     

Electrochemical treatment of diluted cyanide aqueous wastes

The electrochemical oxidation of diluted cyanide aqueous wastes has been studied in a single compartment electrochemical flow cell. It has been determined that the anode material influences greatly the process's performance. Boron doped diamond and PbO₂ anodes can oxidize these wastes in the presence of both sulfate or chloride anions. On the contrary, dimensional stable anodes cannot oxidize cyanide in sulfate‐containing wastewaters, and require the presence of chloride ions. The oxidation of cyanides leads to the formation of cyanate in a first step, and later to the formation of carbon dioxide and nitrogen. There is a net consumption of hydroxyl ions during the process. Energy consumptions in the range 20–70 kWh m^?3 are required to decrease the initial pollutant load by 70–80%. Global current efficiencies in the range 3–8% are obtained. These low current efficiencies are justified by the low cyanide concentrations that the wastes used in this work contain. Copyright © 2005 Society of Chemical Industry     

Reactive processing of LLDPEs in counterrotating nonintermeshing twin-screw extruder. III. Methods of peroxide addition

An ethylene–octene linear low-density polyethylene (LLDPE) was treated with peroxide in a reactive extrusion system. A counterrotating nonintermeshing twin-screw extruder (System 2) was contrasted with a corotating intermeshing twin-screw machine (System 1). In System 2, the peroxide solution was pumped into the melted polymer, while it entered with the polymer pellets in the feed section of System 1. Molecular structure changes and the rheological behavior of peroxide-modified resins are similar in both operations but System 2 is much more effective. Much lower peroxide levels were needed in System 2. However, reactions in this setup were also more difficult to control. The presence of microgel was clearly evident in System 2 products but not in those made in System 1. The results of such reactive extrusion processes depend critically on the method of the peroxide feed and mixing conditions. Reaction conditions that favor optimum economy and peroxide efficiency are those which may compromise product homogeneity. © 1996 John Wiley & Sons, Inc.     

Clinical implications of skeletal muscle blood-oxygenation-level-dependent (BOLD) MRI

Blood-oxygenation-level-dependent (BOLD) contrast in magnetic resonance (MR) imaging of skeletal muscle mainly depends on changes of oxygen saturation in the microcirculation. In recent years, an increasing number of studies have evaluated the clinical relevance of skeletal muscle BOLD MR imaging in vascular diseases, such as peripheral arterial occlusive disease, diabetes mellitus, and chronic compartment syndrome. BOLD imaging combines the advantages of MR imaging, i.e., high spatial resolution, no exposure to ionizing radiation, with functional information of local microvascular perfusion. Due to intrinsic contrast provoked via changes in hemoglobin oxygen saturation, it is a safe and easy applicable procedure on standard whole-body MR devices. Therefore, BOLD MR imaging of skeletal muscle is a potential new diagnostic tool in the clinical evaluation of vascular, inflammatory, and muscular pathologies. Our review focuses on the current evidence concerning the use of BOLD MR imaging of skeletal muscle under pathological conditions and highlights ways for future clinical and scientific applications.     

Einfluß der adsorption von 3-N-alkylaminopropan-1-olen auf das zetapotential von polymeroberflächen

The principle of a measuring system for the determination of ζ-potentials of polymer sheets is described. On sheets of poly(tetrafluoroethene) and homopolystyrene characteristic differences of the ζ-potential after absorption of 3-N-alkylaminopropane-1-oles and dodecylpropylamines in aqueous solutions were detected. The influence of pH, concentration, and C-chain length of the tenside was investigated.