Effect of Ce3+/Ce4+ Couple on Selective Hydrogenation of Crotonaldehyde over Pt/CeO2 Catalyst

2011 ◽  
Vol 233-235 ◽  
pp. 1592-1596
Author(s):  
Guan Qun Xie ◽  
Yan Hui Dai ◽  
Xi Jing Liu ◽  
Meng Fei Luo ◽  
Xiao Nian Li
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Selective Hydrogenation ◽  
Temperature Reduction ◽  
Crotyl Alcohol

By pretreatment of Pt/CeO2catalysts with high temperature reduction and subsequent low temperature reoxidation, the concentration of Ce3+species in the Pt/CeO2catalysts could be adjusted, while at the same time the Pt particle size remained constant. Thus the pure effect of Ce3+/Ce4+couples on the selective hydrogenation of crotonaldehdye could be explored. The investigation provided direct proofs supporting that Ce3+species favors the crotyl alcohol selectivity.

Preparation of a silver nanoparticle-based dual-functional sensor using a complexation–reduction method

2015 ◽  
Vol 17 (33) ◽  
pp. 21243-21253 ◽  
Author(s):  
Fwu-Long Mi ◽  
Shao-Jung Wu ◽  
Wen-Qi Zhong ◽  
Cheng-Yu Huang
Keyword(s):  
Silver Nanoparticles ◽  
High Temperature ◽  
Low Temperature ◽  
Silver Nanoparticle ◽  
Reduction Method ◽  
Ag Nps ◽  
Two Stage ◽  
Temperature Reduction ◽  
Dual Functional

A dual-functional sensor based on silver nanoparticles was synthesized by a two-stage procedure consisting of a low-temperature chitosan–Ag+ complexation followed by a high-temperature reduction of the complex to form chitosan-capped silver nanoparticles (CS-capped Ag NPs).

Study on the Thermodynamics and Kinetics in the Combustion Reaction between Titanium and Boron Powders

2007 ◽  
Vol 351 ◽  
pp. 189-194 ◽  
Author(s):  
K. Wang ◽  
Zheng Yi Fu ◽  
Wei Min Wang ◽  
Yu Cheng Wang ◽  
H. Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Experimental Analysis ◽  
Combustion Temperature ◽  
Raw Materials ◽  
Temperature Range ◽  
Thermodynamics And Kinetics ◽  
Diffusion Controlled ◽  
Calculated Activation

Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calculated activation energies are 140KJ/mol or 355KJ/mol respectively, which is described by a change from dissolution-precipitation controlled process to diffusion-controlled process. With the increase of particle size of the raw materials, combustion temperature and propagating rate will both reduce. The propagating rate decreases with the addition of diluents. Further increase of diluents may result in a stop of the combustion wave halfway or even a failure of ignition.

Effect of Grit Type, Aging Temperature, and Aging Time on Particle Size of Ground Natural Rubber/Zeolite Composite Powder

2016 ◽  
Vol 705 ◽  
pp. 24-29
Author(s):  
Karl C. Ondoy ◽  
Bryan B. Pajarito
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Natural Rubber ◽  
Aging Time ◽  
Aging Temperature ◽  
Composite Powder ◽  
Chain Structure ◽  
Particle Size Range ◽  
Zeolite Composite

This study reports the results of investigation on the main and interaction effects of grit type, aging temperature, and aging time on particle size of ground natural rubber/zeolite (GNR/Z) composite powder using general factorial design of experiment. GNR/Z composite powder produced by mechanical grinding is porous, like an aggregated chain structure. These aggregates exist in clusters of irregular shape. Analysis of variance (ANOVA) shows that the effects of aging temperature and aging time depend on the particle size range. GNR/Z composite powder with large particle size is produced when aging is done at low temperature and short time due to high resistance of rubber to oxidation. On the other hand, GNR/Z composite powder with small particle size is produced when aging is done at low or high temperature and longer aging time. Low temperature condition offers high O2 concentration available to oxidize rubber while high temperature condition leads to more chain scissions due to higher oxidation rate.

Sequential high temperature reduction, low temperature hydrolysis for the regeneration of sulfated NOx trap catalysts

2008 ◽  
Vol 136 (1-2) ◽  
pp. 183-187 ◽  
Author(s):  
Do Heui Kim ◽  
Ja Hun Kwak ◽  
Xianqin Wang ◽  
Janos Szanyi ◽  
Charles H.F. Peden
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Nox Trap ◽  
Temperature Reduction

scholarly journals Preparation and Evaluation of Sunflower Oil Nanoemulsion As a Sunscreen

2019 ◽  
Vol 7 (22) ◽  
pp. 3757-3761
Author(s):  
Anayanti Arianto ◽  
Cindy Cindy
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Sunflower Oil ◽  
Room Temperature ◽  
Ph Value ◽  
Average Particle Size ◽  
Tween 80 ◽  
Average Particle ◽  
Spontaneous Emulsification

BACKGROUND: There are a lot of different types of sunscreen products (oils, sticks, gels, creams, lotions) which can be found on the world's market. Sunscreen product that contains active chemical ingredients sometimes has harmful effects on the skin. Sunflower oil contains vitamin E and acts as a natural sunscreen which can absorb UVB light. The average droplet size of nanoemulsion is between 100 and 500 nm and do not show the problems of stability (creaming, flocculation, coalescence, and sedimentation), which are commonly associated with macroemulsions. AIM: The aim of this study was to prepare and evaluate the sunflower oil nanoemulsion as a sunscreen. METHODS: Sunflower oil nanoemulsions were prepared by spontaneous emulsification method with 3 formulas F1 (Tween 80 38%, sorbitol 22%), F2 (Tween 80 36%, sorbitol 24%), F3 (Tween 80 34%, sorbitol 26%) and 5% sunflower oil as a sunscreen substance. The nanoemulsions were evaluated for particle size, physical stability in room temperature (25 ± 2°C), low temperature (4 ± 2°C) and high temperature (40 ± 2°C) during experiment for 12 weeks of storage, centrifugation at 3750 rpm for 5 hours, viscosity, pH, freeze-thaw test and sun protection value (SPF) value by in vitro. RESULTS: The results of nanoemulsion evaluation showed that nanoemulsion formula F1 had the smallest average particle size of 124.47 nm with yellowish colour, clear, transparent, pH value (6.5 ± 0.1), viscosity value (225 ± 25 cP), did not show any separation or creaming in the centrifugation, and stable during experiment for 12 weeks of storage at room temperature, low temperature and high temperature. The SPF value of all nanoemulsion preparations was higher than that of the emulsion. CONCLUSION: The preparation of the sunflower oil nanoemulsion with a ratio of Tween 80 and sorbitol (38: 22) produces a stable nanoemulsion during the experiment for 12 weeks storage at the room, low and high temperature. The nanoemulsion preparation has higher SPF values compared to the emulsion. This nanoemulsion formulation could be considered more effective in sunscreen cosmetic use compare to the emulsion.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Superconducting Wind Generators with Capacities of 10 MW and Larger

2020 ◽  
Vol 10 (10) ◽  
pp. 59-67
Author(s):  
Victor N. ANTIPOV ◽  
◽  
Andrey D. GROZOV ◽  
Anna V. IVANOVA ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Wind Power ◽  
State Of The Art ◽  
Superconducting Materials ◽  
Commercial Application ◽  
Synchronous Generators ◽  
High Temperature Superconducting ◽  
Wind Generators ◽  
Main Factor

The overall dimensions and mass of wind power units with capacities larger than 10 MW can be improved and their cost can be decreased by developing and constructing superconducting synchronous generators. The article analyzes foreign conceptual designs of superconducting synchronous generators based on different principles: with the use of high- and low-temperature superconductivity, fully superconducting or only with a superconducting excitation system, and with the use of different materials (MgB2, Bi2223, YBCO). A high cost of superconducting materials is the main factor impeding commercial application of superconducting generators. In view of the state of the art in the technology for manufacturing superconductors and their cost, a conclusion is drawn, according to which a synchronous gearless superconducting wind generator with a capacity of 10 MW with the field winding made of a high-temperature superconducting material (MgB2, Bi-2223 or YBCO) with the «ferromagnetic stator — ferromagnetic rotor» topology, with the stator diameter equal to 7—9 m, and with the number of poles equal to 32—40 has prospects for its practical use in the nearest future.

SOMERS LTA COPPER

Alloy Digest ◽  
1980 ◽  
Vol 29 (12) ◽  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Physical Properties ◽  
Copper Foil ◽  
Heat Treating ◽  
Dielectric Substrates ◽  
Printed Circuits

Abstract SOMERS LTA Copper is a wrought copper foil that can be annealed at 350 F in 15 minutes to the full-soft condition; its use simplifies the manufacture of printed circuits (LTA = Low-Temperature Annealable). LTA Copper is especially useful for foil weights up to and including one ounce per square foot (0.0014-inch thick) for laminating to high-temperature dielectric substrates. This datasheet provides information on composition, physical properties, and elasticity as well as fatigue. It also includes information on forming, heat treating, and machining. Filing Code: Cu-407. Producer or source: Olin Corporation.

CHRO-MOW

Alloy Digest ◽  
1958 ◽  
Vol 7 (2) ◽  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Steel Company ◽  
Temperature Performance ◽  
Hot Work Steel ◽  
Crucible Steel ◽  
Red Hardness

Abstract CHRO-MOW is a tough hot work steel which will harden from a relatively low temperature in air. It possesses a desirable combination of toughness and red-hardness. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, and machining. Filing Code: TS-67. Producer or source: Crucible Steel Company of America.

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