scholarly journals Study of the Chemical Interactions Between Iron Phosphides and Iron Silicides

2014 ◽  
Vol 17 (1) ◽  
pp. 67
Author(s):  
G.M. Serzhanov ◽  
V.M. Shevko ◽  
B.A. Lavrov
Keyword(s):  
Energy Minimization ◽  
Phosphorus Release ◽  
Iron Silicides ◽  
Yellow Phosphorus ◽  
Metallurgical Company ◽  
Iron Phosphides ◽  
Lower Temperature ◽  
Phosphorus Production ◽  
Kinetic Mode ◽  
Kinetics Of

<p>This article contains the research results of the thermodynamic modeling of interaction of iron phosphides Fe<sub>2</sub>P and FeP with FeSi<sub>2</sub>, obtained by a method of the total thermodynamic analysis on the basis of the program HSC-5.1 of the Finnish metallurgical company Outokumpu, developed on both a principle of the Gibbs energy minimization, and also kinetics of the phosphorus release by ferrosilicon from the electrothermal ferrophosphorus – a by-product of the yellow phosphorus production. It was found, that temperature of the beginning of the phosphorus formation in systems iron phosphides – FeSi<sub>2</sub> depends on a mole ratio of phosphorus in the phosphides. At the increasing this ratio from 33.3 to 50%, the temperature of the beginning of the phosphorus formation decreases from 1362 K to 1290 K. At lower temperature (773 K) there is the formation of intermediate FeP<sub>2</sub> and FeP in a system Fe<sub>2</sub>P-FeSi<sub>2</sub> and intermediate FeP<sub>2</sub> in a system FeP-FeSi<sub>2</sub>, which react with FeSi<sub>2</sub> with temperature increasing and form a gaseous phosphorus. The process proceeds in kinetic mode and is characterized by apparent activation energy of 281-389 kJ/mol.</p>

scholarly journals Recognition of hydrogen isotopomers by an open-cage fullerene

2013 ◽  
Vol 371 (1998) ◽  
pp. 20110629 ◽  
Author(s):  
Yasujiro Murata ◽  
Shih-Ching Chuang ◽  
Fumiyuki Tanabe ◽  
Michihisa Murata ◽  
Koichi Komatsu
Keyword(s):  
Equilibrium Constants ◽  
Equilibrium Mixture ◽  
Size Difference ◽  
Binding Affinities ◽  
Kinetic Isotope ◽  
Molecular Sizes ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Pressure Hydrogen

We present our study on the recognition of hydrogen isotopes by an open-cage fullerene through determination of binding affinity of isotopes H 2 /HD/D 2 with the open-cage fullerene and comparison of their relative molecular sizes through kinetic-isotope-release experiments. We took advantage of isotope H 2 /D 2 exchange that generated an equilibrium mixture of H 2 /HD/D 2 in a stainless steel autoclave to conduct high-pressure hydrogen insertion into an open-cage fullerene. The equilibrium constants of three isotopes with the open-cage fullerene were determined at various pressures and temperatures. Our results show a higher equilibrium constant for HD into open-cage fullerene than the other two isotopomers, which is consistent with its dipolar nature. D 2 molecule generally binds stronger than H 2 because of its heavier mass; however, the affinity for H 2 becomes larger than D 2 at lower temperature, when size effect becomes dominant. We further investigated the kinetics of H 2 /HD/D 2 release from open-cage fullerene, proving their relative escaping rates. D 2 was found to be the smallest and H 2 the largest molecule. This notion has not only supported the observed inversion of relative binding affinities between H 2 and D 2 , but also demonstrated that comparison of size difference of single molecules through non-convalent kinetic-isotope effect was applicable.

The Self-Decay Characteristics of Chlorine Dioxide in Water

2012 ◽  
Vol 610-613 ◽  
pp. 296-299
Author(s):  
Xin Jie Li ◽  
Dan Nan Jiang ◽  
Yue Jun Zhang
Keyword(s):  
Rate Constants ◽  
Tap Water ◽  
Pure Water ◽  
Decay Behaviour ◽  
Increase With Increase ◽  
Higher Temperature ◽  
Effects Of Temperature ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Temperature Water

In order to learn the ClO2 decay behaviour in tap water, the kinetics of ClO2 decay in pure water was studied. Under the conditions of tap water treatment and keeping away from light, the effects of temperature and pH on ClO2 degradation were investigated. The results show that the ClO2 decay reaction in pure water is the first-order with respect to ClO2, the decay rate constants increase with increase in temperature or pH. At pH=6.87, the rate constants are 0.012h-1(15°C), 0.017h-1(25°C), 0.023h-1(35°C), and 0.029h-1(45°C), respectively. At 25°C, the rate constants are 0.0083h-1(pH=4.5), 0.0111h-1(pH=5.5), 0.0143h-1(pH=6.5), 0.0222h-1(pH=7.5), and 0.0351h-1(pH=8.5), respectively. The experimental data prove that ClO2 is more stable in acidic or lower temperature water than in neutral, alkalescent, or higher temperature water.

Study of the kinetics of calcium molybdate leaching with sodium carbonate solutions

2021 ◽  
pp. 40-46
Author(s):  
Yu. V. Sokolova ◽  
◽  
E. V. Bogatyreva ◽  
Keyword(s):  
Solid Phase ◽  
Stable Phase ◽  
Calcium Carbonates ◽  
Calcium Molybdate ◽  
Carbonate Solutions ◽  
Efficient Recovery ◽  
Kinetic Mode ◽  
Kinetics Of ◽  
Soda Solution ◽  
Rate Controlling Step

Calcium molybdate forms powellite, it is produced as a result of oxidizing roasting of off-grade molybdenum sulphide concentrates and other molybdenum materials with calcium additives (calcium oxides and hydro xides, calcium chlorides) in air at the temperatures of 550–600 oC. Use of Na2CO3 solutions enables an efficient recovery of Мо from CaMoO4 and a quantitative removal of impurities. To determine the optimum conditions for this process, one would need data on CaMoO4 leaching within a broad range of Na2CO3 concentrations and at high temperature and one would need to analyze the composition of the solid phase and the kinetic parameters of the process, i.e. rate and rate-controlling step. The authors look at the CaMoO4 leaching kinetics in 1.0–2.5 mol/l Na2CO3 solutions at 60–90 oC. It was found that the process rate is dictated by the stirring intensity and tends to increase with a rising temperature and the reagent concentration rising in the range of 1.0–1.5 mol/l. A higher concentration of Na2CO3 has no effect on the reaction rate. An apparent reaction order was determined in the Na2CO3 concentration range of 1.0–1.5 mol/l. An equation is proposed for calculating the CaMoO4 dissolution rate for the Na2CO3 solution and the temperature of 80 oC. It was established that a kinetic mode of leaching takes place in the soda concentration range of 1.0–1.5 mol/l amid intensive stirring. It is demonstrated that, within the studied Na2CO3 concentration range, calcite СаСО3 is formed after vaterite, a less stable phase of calcite, with crystallization of double sodium-calcium carbonates Na2Са(CO3)2·nH2O (n = 0, 2, 5) occurring at the same time. With the concentration of soda being >1.5 mol/l, the process is controlled by internal diffusion. In this region, the leaching rate is independent of the Na2CO3 concentration. Formation of double carbonates is associated with an additional consumption of soda. Therefore, when using this system one should consider how CaMoO4 typically dissolves in Na2CO3 solutions. The presence of these compounds in the soda solution after molybdenum leaching may impact the recovery of Мо from the solution using the known techniques. It may also hinder the recirculation of sodium carbonates going for the second leaching cycle.

A study of barium strontium titanate thin films for use in bypass capacitors

1998 ◽  
Vol 13 (1) ◽  
pp. 197-204 ◽  
Author(s):  
B. A. Baumert ◽  
L-H. Chang ◽  
A. T. Matsuda ◽  
C. J. Tracy ◽  
N. G. Cave ◽  
...  
Keyword(s):  
Thin Films ◽  
Perovskite Phase ◽  
Electrical Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Barium Strontium ◽  
Aluminum Metallization ◽  
On Chip ◽  
Lower Temperature ◽  
Kinetics Of

Physical and electrical characterization techniques have been applied to the problem of developing a lower temperature process for spin-on Ba0.7Sr0.3TiO3 thin films and capacitors compatible with on-chip aluminum metallization. The films were prepared by spin-coating from carboxylate precursors and were processed at temperatures between 650 °C and 450 °C. Capacitors annealed at higher temperatures have a dielectric constant (κ) of 382, a C/A of 20 fF/μm2, and a leakage current density of 2 × 10−7 A/cm2 at 3.3 V. Those processed at 450 °C show occasionally promising but inconsistent results, correlated using TEM images with locally variable crystallization into the perovskite phase. The kinetics of the spin-on solution chemical decomposition and crystallization has been investigated through the use of x-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy.

scholarly journals In-depth Characterization of Firefly Luciferase as a Reporter of Circadian Gene Expression in Mammalian Cells

2016 ◽  
Vol 31 (6) ◽  
pp. 540-550 ◽  
Author(s):  
Kevin A. Feeney ◽  
Marrit Putker ◽  
Marco Brancaccio ◽  
John S. O’Neill
Keyword(s):  
Gene Expression ◽  
Mammalian Cells ◽  
Firefly Luciferase ◽  
Luciferase Reporter ◽  
Circadian Gene ◽  
Cultured Fibroblasts ◽  
High Concentrations ◽  
Lower Temperature ◽  
Kinetics Of

Firefly luciferase (Fluc) is frequently used to report circadian gene expression rhythms in mammalian cells and tissues. During longitudinal assays it is generally assumed that enzymatic substrates are in saturating excess, such that total bioluminescence is directly proportional to Fluc protein level. To test this assumption, we compared the enzyme kinetics of purified luciferase with its activity in mammalian cells. We found that Fluc activity in solution has a lower Michaelis constant (Km) for luciferin, lower temperature dependence, and lower catalytic half-life than Fluc in cells. In consequence, extracellular luciferin concentration significantly affects the apparent circadian amplitude and phase of the widely used PER2::LUC reporter in cultured fibroblasts, but not in SCN, and we suggest that this arises from differences in plasma membrane luciferin transporter activity. We found that at very high concentrations (>1 mM), luciferin lengthens circadian period, in both fibroblasts and organotypic SCN slices. We conclude that the amplitude and phase of circadian gene expression inferred from bioluminescence recordings should be treated with some caution, and we suggest that optimal luciferin concentration should be determined empirically for each luciferase reporter and cell type.

scholarly journals Biotin-binding protein from chicken egg yolk. Assay and relationship to egg-white avidin

1976 ◽  
Vol 157 (2) ◽  
pp. 395-400 ◽  
Author(s):  
H B White ◽  
B A Dennison ◽  
M A Della Fera ◽  
C J Whitney ◽  
J C McGuire ◽  
...  
Keyword(s):  
Binding Protein ◽  
Gel Filtration ◽  
Egg Yolk ◽  
Egg White ◽  
Specific Protein ◽  
Chicken Egg ◽  
Biotin Binding ◽  
Lower Temperature ◽  
Chicken Egg Yolk ◽  
Kinetics Of

1. Biotin in chicken egg yolk is non-covalently bound to a specific protein that comprises 0.03% of the total yolk protein (0.8 mg/yolk). This biotin-binding protein is not detectable by the normal avidin assay owing to the biotin being tightly bound. Exchange of [14C]biotin for bound biotin at 65 degrees C is the basis of an assay for this protein. 2. Biotin-binding protein from egg yolk is distinguishable from egg-white avidin on Sephadex G-100 gel filtration, although the sizes of the two proteins appear quite similar. 3. Biotin-binding protein is denatured at a lower temperature and freely exchanges biotin at lower temperatures than does avidin. 4. The biotin-binding protein in egg yolk is postulated to be responsible for the deposition of biotin in egg yolk. D-[carboxyl-14C]Biotin injected into laying hens rapidly appears in the egg bound to yolk biotin-binding protein and avidin. Over 60% of the radioactivity is eventually deposited in eggs. The kinetics of biotin deposition in the egg suggests a 25 day half-life for an intracellular biotinyl-coenzyme pool in the laying hen.

Glancing Angle X-Ray Study of Crystallization of Amorphous Ge at the Ge-A1 Interface

1990 ◽  
Vol 202 ◽  
Author(s):  
S. M. Heald ◽  
J. K. D. Jayanetti ◽  
R. C. Budhani
Keyword(s):  
Initial Period ◽  
Time Characteristic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Limited ◽  
Glancing Angle ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Diffusion Limited Reaction ◽  
Good Agreement

ABSTRACTThe amorphous to crystalline transformation of Ge in Al/Ge thin film couples has been studied using glancing angle EXAFS, x-ray reflectivity and diffraction. It was found that crystallization occurs at a much lower temperature (118-150 °C) than for bulk Ge, and initiates at the Al/Ge interface. X-ray diffraction studies were made at 152 °C to study the kinetics of the reaction. After an initial period we find good agreement with a square root dependence of the time, characteristic of a diffusion limited reaction.

Release Kinetics of Phosphorus in Sediments from Baihua Lake

2012 ◽  
Vol 599 ◽  
pp. 91-95 ◽  
Author(s):  
Jin Mei ◽  
Ji Wei Hu ◽  
Xian Fei Huang ◽  
Li Ya Fu ◽  
Jin Luo ◽  
...  
Keyword(s):  
Organic Phosphorus ◽  
Release Kinetics ◽  
Phosphorus Release ◽  
Release Kinetic ◽  
Iron Aluminum ◽  
P Content ◽  
Elovich Equation ◽  
Release Data ◽  
The Relationship ◽  
Kinetics Of

Release kinetics of phosphorus in 17 sediments samples collected from Baihua Lake were determined, and the relationship between the phosphorus release kinetic parameters and the sediment composition was also investigated. The results showed that both the Elovich equation and power function equation were valid models for describing the phosphorus release data in the 17 sediments. Within the beginning 12 h, the rate of phosphorus release was high, and then decreased. Our correlation analysis demonstrates that there were no significant correlations between the maximum capacity of phosphorus release (Qmax) and the content of total nitrogen (TN), organic matter (OM), calcium-bound phosphorus (Ca-P), and organic phosphorus (OP). But the correlation between Qmax and iron/aluminum-bound phosphorus (Fe/Al-P) content was positive (R2 = 0.6064, P < 0.01), suggesting that Fe/Al-P might be the main contributor to the released phosphorus in the sediments.

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