Nickel Nanoparticles Supported on Silica of Low Surface Area. Hydrogen Chemisorption and TPD and Catalytic Properties

Nickel metal nanoparticles supported on silica of low surface area (15 m² g^-1) were prepared by reduction of nickel acetate by hydrazine in aqueous medium. Their gas-phase stability and surface properties depended on thermal pre-treatment under H₂ or air atmosphere. Small nickel particles (<10 nm), in oxidized or reduced state, are strongly resistant to reductive or oxidative treatment respectively. For H₂-treated catalysts, H₂ chemisorption and TPD results suggested the occurrence of spillover hydrogen between the metal nickel phase and silica. For air then H₂ treated catalysts, hydrogen spillover seemed to involve the NiO phase. The activity of the catalysts in gas-phase benzene hydrogenation also depended on the thermal pre-treatment. Pre-calcined then reduced catalysts exhibited higher TOFs than non pre-calcined catalysts, suggesting that the presence of NiO phase may have influenced the hydrogenation process.     

Optimal parameters for performant heterojunction InGaP/GaAs solar cell

We demonstrated mainly some of the different parameters effects -as a function of temperature-as window layers, thickness, and doping of the various layers (emitter, base and BSF) on the performances of InGaP/GaAs solar cell. First, we have varied the molar fraction of different layers; their thickness and the doping of both emitters and bases. We have registered the result of each variation until obtaining optimal parameters. In a second stage, we have simulated the InGaP/GaAs cell without window layers which results in η = 12.47% and η = 22.14% for eliminating top and bottom windows respectively. Then, the elimination of layer BSFs(back surface field) on the back face of the considered cell causes a remarkable decrease in open circuit voltage Voc and output η which reached 1.57 V and 11.95% respectively. In a last stage, we optimized and simulated the performances of the InGaP/GaAs dual-junction solar cell for its optimal parameters while varying its operation temperature from 300 K to 375 K with an increment of 25 °C using a virtual wafer fabrication TCAD Silvaco. The optimization at 300 K led to the following results Icc = 15.19 mA/cm^?2, Voc = 2.53 V, FF = 91.32% and η = 25.43% which are close with those found in literature for In_(1?x)Ga_(x)P(x is molar fraction: x = 0.5). Therefore, we could determine the critical parameters of the cell and optimize its main parameters to obtain the highest performance for a dual junction solar cell. This work will pave the way with new prospects in the field of the photovoltaic. The structure simulation will simplify the manufacturing processes of solar cells; will thus reduce the costs while producing high outputs of photovoltaic conversion.     

Quantum-inspired firefly algorithm with particle swarm optimization for discrete optimization problems

The firefly algorithm is a recent meta-heuristic inspired from nature. It is based on swarm intelligence of fireflies and generally used for solving continuous optimization problems. This paper proposes a new algorithm called “Quantum-inspired Firefly Algorithm with Particle Swarm Optimization (QIFAPSO)” that among other things, adapts the firefly approach to solve discrete optimization problems. The proposed algorithm uses the basic concepts of quantum computing such as superposition states of Q-bit and quantum measure to ensure a better control of the solutions diversity. Moreover, we use a discrete representation for fireflies and we propose a variant of the well-known Hamming distance to compute the attractiveness between them. Finally, we combine two strategies that cooperate in exploring the search space: the first one is the move of less bright fireflies towards the brighter ones and the second strategy is the PSO movement in which a firefly moves by taking into account its best position as well as the best position of its neighborhood. Of course, these two strategies of fireflies’ movement are adapted to the quantum representation used in the algorithm for potential solutions. In order to validate our idea and show the efficiency of the proposed algorithm, we have used the multidimensional knapsack problem which is known as an NP-Complete problem and we have conducted various tests of our algorithm on different instances of this problem. The experimental results of our algorithm are competitive and in most cases are better than that of existing methods.     

Extrusion parameters and consumer acceptability of a peanut-based meat analogue

Despite its high protein content and low cost, defatted peanut flour (DPF) remains underutilised in human foods. The objectives of this study were to: (1) determine the best extrusion parameters for a peanut-based textured meat analogue (TMA); (2) develop new TMA products from DPF and (3) evaluate their consumer acceptability. Preliminary runs using a wide range of extrusion parameters were conducted. A central composite RSM design was used to determine the optimal extrusion conditions within the best ranges revealed by the preliminary runs. Three levels of moisture, screw-speed and barrel temperature were used in 31 runs. Expansion ratio, bulk density, texture profile, water absorption/solubility indexes of the extrudates were determined and used as indicators of product quality. Peanut-based TMAs produced at optimal extrusion conditions were flavoured with beef flavour and evaluated by a 60-member sensory panel for flavour, texture, and overall liking, using a 9-point hedonic scale. Optimisation studies revealed that the most important extrusion conditions are in descending order: protein content, temperature, moisture and screw-speed. Extrusion conditions that produced the best TMA were 60–65% protein, 50–55% moisture, 160–165 °C and 80–90 r.p.m. Sensory acceptability of snacks incorporating peanut-based TMAs was similar or better than those containing soya-based TMAs in terms of flavour, texture, off-flavour and overall liking. TMA produced from inexpensive DPF has the potential to compete with commercial meat analogues, thereby adding value to the peanut industry.     

Three small-scale laboratory steeping and wet-milling procedures for isolation of starch from sorghum grains cultivated in Sahara of Algeria

Starch was isolated from white and red sorghum. The values of thousand kernel weight, test weight, starch and protein contents were respectively 33.05 ± 0.5 (g), 692.85 ± 0.65 (g/l), 65.05 ± 0.19% and 12.27 ± 0.18% for the white sorghum grains and 27.70 ± 0.13 (g), 736.55 ± 0.25 (g/l), 66.37 ± 0.31% and 12.59 ± 0.03% for the red sorghum grains.Three small-scale laboratory steeping procedures were used: steeping in NaOH solution, in SO₂ solution and in SO₂ solution containing lactic acid. The effect of the concentration of steeping solutions and time of steeping on starch isolate and yield were studied. The starch recovery, starch purity, moisture, amylose, protein content and particle size distribution ranged from 64.8% to 80.4%, 92.61 ± 0.54% to 99.29 ± 0.55%, 11.84% to 14.43%, 27.71 ± 0.41% to 29.88 ± 0.56%, 0.31 ± 0.01% to 0.78 ± 0.01% and 4.0 μm to 36 μm, respectively.The high grain quality traits and isolated starch properties indicated that Algerian sorghum cultivars can have many applications in nutrition and food technology.     

Enhanced cholesterol‐ and triglyceride‐ lowering effect of West African green tea

‘The Vert’ is a special type of green tea widely consumed in West Africa and locally associated with many health benefits. However, limited research has been conducted to evaluate its health benefits, such as its enhanced hypolipidemic potential. The objectives of this study were to (1) evaluate the cholesterol‐ and triglyceride‐lowering effects of West African green tea (WAGT) as affected by diet and tea intake, (2) determine the impact of WAGT consumption on the CHD risk ratio, and (3) explore possible mechanisms through which WAGT improves serum lipid profile. Forty‐five male Wistar rats were randomly assigned to one of nine treatment combinations, three diets (regular, high‐cholesterol, and trans‐fat diets) and three fluid sources (no tea, diluted tea, and concentrated tea). After 6 weeks of feeding, animal blood, liver, and feces were harvested. Total cholesterol, HDLc, LDLc, and triglycerides in serum, liver, and feces were determined. The concentrations of bile acids in feces were also measured. WAGT significantly lowered serum and liver cholesterol (30% and 15%, respectively) and increased serum HDL cholesterol (30%). It also reduced liver enlargement caused by storage of excess lipids in high‐cholesterol diet. Overall, the CHD risk ratio was cut by two‐thirds in rats fed high‐cholesterol diet and WAGT. A marked increase in fecal total lipids, cholesterol (60%), and bile acids (50%) was observed in rats that consumed WAGT compared to the control group. These beneficial effects could be attributed to the significantly high flavonoid content of WAGT. Copyright © 2007 Society of Chemical Industry     

A novel epsilon-dominance Harris Hawks optimizer for multi-objective optimization in engineering design problems

Neural Computing and Applications - In this article, A Multi-Leaders Guided Harris Hawks optimizer using Epsilon-Dominance relation is developed for solving multi-objective optimization problems....