Experimental results of nanofluids flow effects on metal surfaces

The results of an experimental study on the effects of the flow of nanofluids (water-based suspensions of nanometer-sized solid particles) on metal surfaces are presented. Either different nanofluids (containing TiO₂, Al₂O₃, ZrO₂, and SiC, respectively) and different target materials (aluminum, copper, stainless steel) have been investigated, under similar operating conditions. Different behaviors were observed depending on the specific combination nanofluid-target material, which in some cases led to severe damaging of the tested target, thus highlighting the need for an adequate preliminary investigation of the possible interactions between the selected nanofluid and the apparatus materials, before its adoption as heat transfer fluid.     

Determination of bioaccessibility of beta-carotene in vegetables by in vitro methods

The in vitro method in use for the determination of beta-carotene bioaccessibility involves simulated gastrointestinal digestion followed by ultracentrifugation to separate the micellar fraction containing bioaccessible beta-carotene and its quantitation. In this study, the suitability of two alternatives viz., membrane filtration and equilibrium dialysis were examined to separate the micellar fraction. Values of beta-carotene bioaccessibility obtained with the membrane filtration method were similar to those obtained by the ultracentrifugation method. Equilibrium dialysis was found not suitable for this purpose. Among the vegetables analyzed, fenugreek leaves had the highest content of beta-carotene (9.15 mg/100 g), followed by amaranth (8.17 mg/100 g), carrot (8.14 mg/100 g) and pumpkin (1.90 mg/100 g). Percent bioaccessibility of beta-carotene ranged from 6.7 in fenugreek leaves to 20.3 in carrot. Heat treatment of these vegetables by pressure cooking and stir-frying had a beneficial influence on the bioaccessibility of beta-carotene from these vegetables. The increase in the percent bioaccessibility of beta-carotene as a result of pressure-cooking was 100, 48 and 19% for fenugreek leaves, amaranth and carrot, respectively. Stir-frying in presence of a small quantity of oil led to an enormous increase in the bioaccessibility of beta-carotene from these vegetables, the increase being 263% (fenugreek leaves), 192% (amaranth leaves), 63% (carrot) and 53% (pumpkin).     

Studies of Cu(II)–IO4− initiated graft copolymerization of methyl methacrylate from defatted pineapple leaf fibres

A study of the graft copolymerization of methyl methacrylate (MMA) from defatted pineapple leaf fibre (PALF) was carried out in the temperature range 45–55 °C, using a copper sulphate (CuSO₄) and potassium periodate (KIO₄) combination as initiator in an aqueous medium. Effects of variation of time and temperature, concentration of Cu(II), KIO₄ and MMA, the amount of PALF, and also the effects of some inorganic salts and organic solvents on the percentage of graft yield have been investigated. On the basis of experimental findings, a reaction mechanism is proposed. FTIR spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy of the original defatted PALF and MMA grafted PALF have been carried out. The thermal stability of PALF is improved through grafting. © 1999 Society of Chemical Industry     

Regional cerebral blood flow determination using 133Xe and a standard rotating gamma-camera

While most of the methods for quantitative regional cerebral blood flow (rCBF) determination in man requires expensive fast devices, a method is proposed using single photon emission computed tomography with a conventional rotating gamma camera and 133Xe inhalation. It is tested using a computer simulation of a cerebral exam and a simplified CBF map as a model. The results obtained show that this method is relevant and can be tested in clinical studies.     

Automated Design Flow for Multi-Functional Dataflow-Based Platforms

The implementation of processing platforms supporting multiple applications by runtime reconfigurations on dedicated hardware modules requires the solution of different problems. These problems are notably not-trivial since both platform and application complexities increase year after year. As a consequence, the design process is both time and resource demanding. System configuration along with resources management and mapping remain one of the most challenging problem, particularly when runtime adaptation is required. In this direction, the ISO/IEC SC29WG11 committee (MPEG) has developed the so called MPEG-RVC standards ISO/IEC 23001-4 and 23002-4. This standard provides specifications of video codecs in the form of dataflow programs. In this paper, an integrated design flow to derive optimized multi-functional platforms directly from disjoined high-level specifications is presented. To the authors’ best of knowledge, such an optimization, synthesis and mapping methodology for coarse-grained reconfigurable systems design does not exist within the MPEG-RVC framework. The design flow presented in this paper leverages on an integrated set of independently designed tools, all supporting the RVC standard. Results assessment has been carried out on three different scenarios: an MPEG-RVC decoder, a standard baseline MPEG-RVC JPEG codec and a generalized reconfigurable multi-quality JPEG encoder. For all these scenarios, the proposed design flow has been targeted for a Xilinx Virtex 5 FPGA. Results show how this approach is capable of yielding a reconfigurable design that preserves the original performance of the stand alone non-reconfigurable platform providing, at the same time, considerable area savings featuring a larger set of functionalities. Moreover, platforms programmability, on the basis of the required functionality ID, is automatically handled at runtime without any designer effort.     

Studies on dissolution kinetics of dolime in electrothermal magnesium slag

The electrothermal process of magnesium metal production is a promising route, where large sized internally heated reactor is used for magnesium production resulting in less energy and labour intensive and high space-time yield process. However, the dissolution behavior of dolime in the electrothermal slag has been found critical for the process optimization. In this paper, the dissolution kinetics of the dolime in the slag was discussed. Quaternary slag (CaO-Al₂O₃-SiO₂-MgO) was prepared having basicity CaO/SiO₂ ≥ 1.8 and Al₂O₃/SiO₂ ≥ 0.26 for dolime dissolution studies by static hot dip method. Prior to the experiments, FactSage calculations were carried out varying temperatures and slag compositions. In the kinetic studies, dolime particles 10–15 mm size was added in slag melted at 1450, 1500 and 1550°C and samples were taken at various time intervals. The chemical analysis of slag sample was carried out to investigate the dissolution kinetics to establish the rate expression. The activation energy for the process was calculated for different models used in study and was found to be in the range of 130–270 kJ/mol. SEM analysis was done for surface analysis of reacted particles. This study would be helpful in optimizing the dolime charging rate during pilot scale trials for electrothermal magnesium production at CSIR-NML, Jamshedpur.     

Influence of Dynamic Precipitation During Low Cycle Fatigue of Under-Aged AA6063 Alloy

The present study is aimed to understand the influence of dynamic precipitation on the low cycle fatigue (LCF) behavior of an under-aged (UA) AA6063 Al–Mg–Si alloy. This was accomplished by the estimation of plastic strain energy density (PSED) at varied isolated cycles during LCF of the UA alloy with subsequent comparison of these results with those of peak-aged (PA) and over-aged (OA) ones. The LCF tests of the UA alloy were carried out in the range of strain amplitudes of 0.2–1.0 % together with the evolution of hardness and tensile properties. The UA alloy shows Masing behavior, evaluated in terms of the variation of Bauschinger strain with plastic strain amplitude, and exhibits continuous hardening till failure unlike the PA and OA alloys. Higher average PSED value for the UA alloy in comparison to that for the PA and the OA alloys indicates dynamic precipitation during cycling; the magnitudes of average PSED were calculated using a proposed method. In addition, pronounced increase in the post LCF hardness values substantiate the dynamic precipitation.     

Application of quantum dot gate nonvolatile memory (QDNVM) in image segmentation

This paper presents the application of quantum dot gate nonvolatile memory (QDNVM) in image processing application. The charge accumulation in the gate region varies the threshold voltage of QDNVM, which can be used as a reference voltage source in a comparator circuit. A simplified comparator circuit can be implemented using the QDNVM. In this work, the use of QDNVM-based comparators in image processing specially image segmentation is demonstrated, which can be efficient in future image processing application.     

Women and WASH in Nepal: a scoping review of existing literature

ABSTRACT

The relationship between gender and water, sanitation and hygiene (WASH) services is an issue for many developing states. This scoping review demonstrates that in Nepal, women bear the major social burden of inadequate WASH services and are under-represented in WASH-related policies and programmes. Four themes emerge: gender and water projects; lack of equal female participation in WASH policy development and implementation; women’s access to water; and menstruation and menstrual hygiene. Major cultural barriers embedded in Nepali society limit women’s access, agency and participation in WASH-related policy and practice.     

Hydrogen production via sulfur-based thermochemical cycles: Part 2: Performance evaluation of Fe2O3-based catalysts for the sulfuric acid decomposition step

The sulfuric acid dissociation reaction, via which the production of SO₂ and O₂ is achieved, is the most energy intensive step of the so-called sulfur-based thermochemical cycles for the production of hydrogen. Efforts are focused on the feasibility and effectiveness of performing this reaction with the aid of a high-temperature energy/heat source like the sun. Such coupling can be achieved either directly in a solar reactor by concentrated solar radiation, or indirectly by means of a heat-exchanger/decomposer reactor using a suitable heat transfer fluid. Since a very limited amount of work regarding the potential formulations and sizing of such suitable reactors has been performed so far, the present work addresses further steps necessary for the efficient design, manufacture and operation of such reactors for sulfuric acid decomposition. In this respect, parametric studies on the SO₃ decomposition with iron(III) oxide-based catalysts were performed investigating the effect of temperature, pressure and space velocity on SO₃ conversion. Based on these results, an empirical kinetic law suitable for the reactor design was developed. In parallel, siliconised silicon carbide honeycombs coated with iron(III) oxide were prepared and tested in structured laboratory-scale reactors to evaluate their durability (i.e. activity vs. time) during SO₃ decomposition, with the result of satisfactory and stable performance for up to 100 h of operation. The results in combination with characterization results of “aged” materials can provide valuable input for the design of prototype reactors for sulfuric acid decomposition.