Synthesis,Crystal Structural and Electrical Conductivity Properties of Fe-Doped Zinc Oxide Powders at High Temperatures

The synthesis,crystal structure and electrical conductivity properties of Fe-doped ZnO powders(in the range of 0.25-15 mol%) were reported in this paper.I-phase samples,which were indexed as single phase with a hexagonal(wurtzite) structure in the Fe-doped ZnO binary system,were determined by X-ray diffraction(XRD).The solubility limit of Fe in the ZnO lattice is 3 mol% at 950℃.The above mixed phase was observed.And the impurity phase was determined as the cubic-ZnFe 2 O 4 phase when compared with standard XRD data using the PDF program.This study focused on single I-phase ZnO samples which were synthesized at 950℃ because the limit of the solubility range is the widest at this temperature.The lattice parameters a and c of the I-phase decreased with Fe-doping concentration.The morphology of the I-phase samples was analyzed with a scanning electron microscope.The grain size of the I-phase samples increased with heat treatment and doping concentration.The electrical conductivity of the pure ZnO and single I-phase samples was investigated using the four-probe dc method at 100-950℃ in air atmosphere.The electrical conductivity values of pure ZnO,0.25 and 3 mol% Fe-doped ZnO samples at 100℃ were 2×10-6,1.7×10-3 and 6.3×10-4 S.cm-1,and at 950℃ they were 3.4,8.5 and 4 S.cm-1,respectively.     

Hardness and Wear Behaviours of Al Matrix Composites and Hybrid Composites Reinforced with B4C and SiC

Powder Metallurgy and Metal Ceramics - The conversion into the desired shape of the metal powders using Powder Metallurgy (PM) method enables economically mass productions. This case allows...     

Changes in the engineering properties of marble in fire-exposed columns

Two marble columns in the bottom floor of a school building were exposed to intensive heat in the fire, and were subject of a debate about their load-carrying capacity following the event. After their removal from their original spots, series of tests on column samples were carried out to investigate variations in their engineering characteristics due to fire hazard. The temperature at the surface of the marble columns hit by the flames directly during the fire was estimated to be on the order of 500 °C using an empirically established relationship between porosity and temperature on intact marble core samples. Results of mechanical tests indicated that marble columns were still holding a significant load-carrying capacity despite 23% loss of strength at fire temperature. The spallings at the corners of the blocks forced the board of education to give the decision of replacing the gray marble columns with steel members. Occurrence of these spallings is attributed to stress concentrations and widening of micro fractures. Based on the results of mechanical, physical and chemical tests, a methodology to assess influence of fire hazard on marble and similar geological materials was developed.     

DESIGN AND PERFORMANCE OF AN ORIGINAL FRENCH SOLAR HEATING SYSTEM: DIRECT SOLAR FLOOR HEATING

Direct Solar Floor Heating ( DSFH) is an original solar heating system made of a set of water circulation pipes embedded in a concrete floor which is directly connected to the solar collectors without heat exchanger or any other storage. The concrete slab is thick enough to be used as storage. Performance of many installations in France have been measured and give satisfaction. Furthermore, a simplified sizing method has been proposed. We set forth simulations with EMGP2, in order to improve both of these results and to optimize the economic and technical performances of the system. An optimum size which the method did not anticipate is indeed found if we correctly took into account the function of the floor in the system. Two points have to be supervised: comfort and regulation for which some preliminary informations are given. A methodology is proposed in order to analyse bare results from measured data.     

Essential elements and contaminants in tissues of commercial pelagic fish from the Eastern Mediterranean Sea

BACKGROUND: It is important to determine the concentrations of essential and non‐essential metals in fish for human health. The essential elements and contaminants (Pb and Cd) were determined seasonally in the muscle and liver of some pelagic fish species round herring (Etrumeus teres), chub mackerel (Scomber japonicus), golden grey mullet (Liza aurata) and Mediterranean horse mackerel (Trachurus mediterraneus) from the Iskenderun Bay, Eastern Mediterranean Sea. RESULTS: The Na, K, Ca and Mg were the most abundant elements in muscle and liver tissues. The Na, K, Ca and Mg concentrations in fish tissues were between 51.7 and 3426 mg kg^?1. Muscle accumulated the lowest levels of elements. Trace element and contaminant levels in muscle were highest in spring and summer. The Cu, Zn and Cr concentrations were highest in summer. The Ni, Mn and Fe concentrations were highest in spring. The maximum Pb concentrations in the muscle and liver of fish species was 0.39 and 0.80 mg kg^?1 in autumn. The maximum Cd concentration in the muscle of fish was 0.27 mg kg^?1 in spring and the maximum Cd concentration in the liver was 0.78 mg kg^?1 in summer. CONCLUSION: The Cr, Pb, Cd, Cu and Zn levels in muscle were found to be lower than permissible limits reported by various authorities. Estimated weekly and daily intake for Pb and Cd by consumption of fish muscle were far below the PTWI and PTDI values established by FAO/WHO. Copyright © 2009 Society of Chemical Industry     

Effects of dietary black cumin seed (Nigella sativa L.) on performance,egg traits,egg cholesterol content and egg yolk fatty acid composition in laying hens

BACKGROUND: The objective of this study was to determine the effects of dietary black cumin seed on performance, egg traits, egg cholesterol content and egg yolk fatty acid composition in laying hens during a 12 week period. For this purpose a total of 160 Lohmann Brown laying hens 36 weeks of age were allocated to four dietary treatments with one control group and three treatment groups. Black cumin seed (Nigella sativa L.) was used at the level of 5, 10 and 15 g kg^?1 in the diets of the first, second and third treatment groups, respectively. RESULTS: Dietary treatments did not significantly affect body weight, feed intake, egg production, egg quality characteristics and blood parameters. Diets containing 10 and 15 g kg^?1 black cumin seed increased egg weight (P < 0.01), improved feed efficiency (P < 0.01) and decreased egg yolk cholesterol, saturated fatty acids (% of total fatty acid methyl esters) and the ratio of saturated to unsaturated fatty acids (P < 0.05) compared to the diet of control group. CONCLUSION: Dietary black cumin seed at the level of 10 and 15 g kg^?1 had beneficial effects on egg weight, feed efficiency, egg cholesterol content and egg yolk fatty acid composition. Therefore it can be used at the level of 10 and 15 g kg^?1 in the diets of laying hens. Copyright © 2009 Society of Chemical Industry     

Particle size distribution based evaluation of biodegradation and treatability for leachate from organic waste

BACKGROUND: The study evaluated the relationship between particle size distribution (PSD) of chemical oxygen demand (COD) and treatability of leachate generated by organic waste. PSD determinations were performed together with physico‐chemical and biological treatability studies. Leachate biodegradation was also evaluated by means of oxygen uptake rate (OUR) profiles and experimental results were used for calibration of the adopted mathematical model. RESULTS: The leachate was characterized by a COD content of 80 000 mg L^?1 in summer. PSD analysis showed a bimodal distribution with around 60% of the COD below 2 nm and 25% above 1600 nm. Chemical treatment by lime and alum provided limited COD removal (30‐35%). The extent of COD removal was higher than the particulate COD fraction above 1600 nm, it also occurred in the soluble range below 2 nm through adsorption. A modeling study indicated three major COD fractions that could be correlated with PSD analysis: readily biodegradable COD and slowly biodegradable COD in the soluble range and hydrolyzable COD fraction in the particulate range. CONCLUSION: PSD‐based COD fractionation adequately explained limitations of chemical treatment efficiency; it was also a reliable complement to the currently used respirometric tests for biodegradation, providing insight to the fate of different COD fractions included in the soluble range (<2 nm) and yielding concrete supporting information on the generation of soluble residual microbial products. Copyright © 2011 Society of Chemical Industry     

Glass Formation and Characterization Studies in the TeO2–WO3–Na2O System

Glass formation behavior of the TeO₂–WO₃–Na₂O system was studied by using conventional melt‐quenching technique. A wide glass formation range was determined for the first time in the literature and thermal, physical, and structural characterization of sodium‐tungsten‐tellurite glasses were realized using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy techniques. Glass transition (T_g) and crystallization (T_c/T_p) temperatures, glass stability (?T), density (ρ), molar volume (V_M), oxygen molar volume (V_O), and oxygen packing density (OPD) values and structural transformations in the glass network were investigated according to the equimolar substitution of TeO₂ by Na₂O+WO₃ and changing Na₂O or WO₃ at constant TeO₂.     

Chemical and physical changes in cottonseed oil during deodorization

The effects of deodorization time and temperature on the physical and chemical properties of cottonseed oil were investigated. Higher temperatures and longer times lead to increases in free fatty acids, peroxide value, viscosity and refractive index while iodine value, unsaponifiable matter and induction period decreased.