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11.
The interaction of different metal oxides such as Co3O4, NiO, Al2O3, Cr2O3, Fe2O3 and SiO2 with Na2SO4 at a temperature of 1100 and 1200 K in flowing oxygen has been studied. The thermogravimetric studies for each system were
carried out as a function of Na2SO4 in the mixture. The presence of different constituents in the reaction products were identified by X-ray diffraction analysis
and the morphologies of the reaction products were characterized using metallography and scanning electron microscopy (SEM).
The formation of products was also investigated by thermodynamic computation of free energies of the reactions and the study
of relevant equilibrium phase diagrams. The soluble species in the aqueous solutions of the reaction products were determined
quantitatively using atomic absorption spectrophotometry.
The high temperature interaction products usually contain a 3-phase structure namely, Na2O·M2O
x
, M2O
x
and metal sulphide and/or metal sulphate. The formation of Na2O·M2O
x
depends upon the solid state solubility of metal oxide in the molten salt at high temperatures. Under limited solubility
conditions Na2O·M2O
x
is invariably formed, but as soon as this condition is relaxed the oxide. M2O
x
, precipitates and forms a separate phase. 相似文献
12.
Nurcan Calis Acikbas Ender Suvaci Hasan Mandal 《Journal of the American Ceramic Society》2006,89(10):3255-3257
Functionally graded SiAlON ceramics (FG-SiAlONs) were successfully prepared by the tape casting and lamination approach. Non-aqueous SiAlON slurries with five different α to β-SiAlON ratios (85α:15β, 70α:30β, 55α:45β, 40α:60β, and 25α:75β) were prepared by a 66 methyl ethyl ketone/34 ethanol (vol%) mixture. Phase and microstructure analyses incorporation with hardness measurements clearly show that the FG-SiAlONs, prepared by tape casting, exhibit a continuous and gradual change in composition and hardness. Thus, the tape casting approach is a viable method to produce FG-SiAlONs with a precisely controlled composition, and subsequently properties, as a function of position. 相似文献
13.
An on-chip high voltage tolerant 4VDD charge pump with symmetrical architecture in a standard low voltage 1.8 V 0.18 /spl mu/m CMOS process is presented. For a 250 k/spl Omega/ load, circuit efficiency of the charge pump is approximately 71%. All the MOS transistors satisfy typical voltage stress related reliability requirements for standard low voltage CMOS devices. 相似文献
14.
High-T
c
Bi(Pb)-Sr-Ca-Cu-O thin films have been made on single-crystal MgO substrates using high-pressure dc sputtering technique. X-ray studies confirm the crystallinity and highly oriented structure withc-axis perpendicular to the substrate. By optimizing the annealing schedule the formation of the high-T
c
phase is stabilized. The best film exhibited superconducting transition temperature with zero-resistance temperature,T
c(0), as high as 101 K. Temperature dependence ofJ
c
indicates the presence of Josephson-type weak links. 相似文献
15.
R Fukuda XT Nguyen N Ishimura S Ishihara A Chowdhury N Kohge S Akagi M Watanabe S Fukumoto 《Canadian Metallurgical Quarterly》1995,172(5):1191-1197
Hepatitis B virus (HBV) carriers with antibody to hepatitis e antigen comprise asymptomatic carriers (ASCs), who have low replication levels of HBV, and patients with chronic active hepatitis (CAH), who have high levels of viral replication. To investigate whether defects in the X protein might be responsible for this difference in the level of viral replication, nucleotide sequences of X and precore gene regions in serum HBV were analyzed in 19 ASCs and 9 CAH patients. All patients had a point mutation creating a stop codon in the precore region. Seventeen ASCs (87.3%) had identical mutations consisting of 4 noncontiguous 1-bp deletions or an 8-bp deletion, both of which truncate the normal X protein, whereas no CAH patient had an X gene mutation (P < .001). Thus, deletion of the X protein might be responsible for the low levels of viral replication in ASCs. 相似文献
16.
SI Chowdhury BJ Lee D Mosier JH Sur FA Osorio G Kennedy ML Weiss 《Canadian Metallurgical Quarterly》1997,117(4):295-310
CI-994 (acetyldinaline) is an orally active anticancer drug currently in Phase 1 clinical trials. To assess its preclinical toxicity, CI-994 was administered orally as suspensions to Wistar rats (10/sex/dose) and in capsules to beagle dogs (3/sex/dose) once daily for two weeks. Doses were 1.5, 5, and 15 mg/kg for rats (9, 30, and 90 mg/m2, respectively), and 0.5, 2, and 5 mg/kg for dogs (10, 40, and 100 mg/m2, respectively). Systemic exposure was dose-proportional based on toxicokinetic analysis in dogs. Severe clinical signs and mortality occurred at the highest dose in both species beginning on Day 10. Neutropenia, lymphocytopenia, thrombocytopenia, lymphoid depletion, bone marrow hypocellularity, and testicular degeneration were observed in both species, primarily at the mid- and high-doses. Despite continued treatment, neutrophil counts in dogs returned to control levels in Week 2. Other microscopic findings in rats included splenic hematopoietic depletion at all doses and epithelial cell necrosis in various tissues at 15 mg/kg. Additional bone marrow changes in dogs involved myeloid and megakaryocyte hyperplasia at 2 mg/kg and abnormal myeloid and megakaryocyte maturation at 2 and 5 mg/kg. Except for the testicular effects in both species, all changes were reversible within a 4-week (rat) or 9-week (dog) recovery period. The results of these studies show that target organ effects of CI-994 principally involve tissues with rapidly dividing cell populations and that bone marrow suppression is the dose-limiting toxicity. CI-994 also seems to interfere with the release and/or maturation of cells in the bone marrow. 相似文献
17.
Yeddanapudi S.R.K. Yuan Li McCalley J.D. Chowdhury A.A. Jewell W.T. 《Power Systems, IEEE Transactions on》2008,23(2):287-295
Asset management is an important activity in present day distribution system planning and operation. Utilities are constantly striving to optimize the use of resources available for maintenance while ensuring system reliability is within satisfactory limits. This paper proposes a method to allocate maintenance resources to various distribution system assets. To determine the effects of maintenance, a predictive reliability assessment tool is developed. This paper describes the model on which this tool is based. The results obtained from reliability assessment can be used along with an optimizer to allocate resources to various maintenance tasks in a distribution system. 相似文献
18.
A.B. Bourlinos S. RayChowdhury R. Herrera D.D. Jiang Q. Zhang L.A. Archer E.P. Giannelis 《Advanced functional materials》2005,15(8):1285-1290
Recently, we have developed a novel family of functionalized nanostructures that exhibit liquid‐like behavior in the absence of solvents and preserve their nanostructure in the liquid state. The gallery of nanostructures developed so far includes functionalized silica and magnetic iron oxide nanoparticles, layer‐like organosilicate nanoparticles, polyoxometalate clusters, and organic–inorganic hybrid networks. In an effort to demonstrate the wider applicability of this concept and to provide a deeper insight into this class of materials, the present work cites additional paradigms of functionalized nanostructures with similar behavior as above. In one case, surface functionalization of anatase nanoparticles (TiO2, an inorganic nanostructure) with a quaternary ammonium organosilane leads to ionically modified nanoparticles that, when electrostatically combined with a poly(ethylene glycol) (PEG)‐tailed sulfonate anion, exhibit liquid‐like behavior in the absence of solvents. In a different but quite interesting case of a bionanostructure, ion‐exchange functionalization of a DNA oligonucleotide with a PEG‐tailed quaternary ammonium cation leads to an easily separable liquid derivative with attractive features. These examples show the versatility of this concept over a range of nanostructures. 相似文献
19.
20.
A full analysis is shown in this paper for the cost of kWh generated from photovoltaic station located in Kuwait. By using a 21 years weather data for Kuwait, the yearly generated energy was found by proposing the PV station capacity with known panels tilt angle. The cost of kWh generated from PV station was compared with the kWh generated from conventional units in the country. A sensitivity analysis was done to some factors; capital cost per installed PV peak watt, discount rate, and operating peak hours, which affect the cost of kWh production from both PV and conventional units. If the PV station is proposed to be installed in Kuwait, the capital cost per PV installed peak watt must be less than today's prices. 相似文献