scholarly journals The Catalytic Decomposition of 2-Propanol on Magnesium Oxide

1975 ◽  
Vol 53 (18) ◽  
pp. 2729-2733 ◽  
Author(s):  
Ian M. Hoodless ◽  
G. Douglas Martin
Keyword(s):  
Magnesium Oxide ◽  
Abrupt Change ◽  
Catalytic Decomposition ◽  
Pure Magnesium ◽  
Lithium Oxide ◽  
Pulse Reactor ◽  
Temperature Range ◽  
Anion Vacancies ◽  
Increasing Temperature

The catalytic decomposition of 2-propanol on powders of "pure" and lithium oxide doped magnesium oxide has been investigated in the temperature range 300–450 °C by a pulse reactor technique. With the "pure" magnesium oxide samples the selectivity for dehydrogenation decreases with increasing temperature with an abrupt change in the region of 375 °C. The effect of the lithium oxide dopant is to depress the selectivity for dehydrogenation at the lower temperatures. The dopant does not appear to affect the dehydration activity and the decrease in selectivity is ascribed to the strong chemisorption of acetone at anion vacancies.

The adsorption of hydrogen and oxygen on magnesium oxide: The effect of γ-irradiation

1977 ◽  
Vol 30 (5) ◽  
pp. 971 ◽  
Author(s):  
RJ Breakspere ◽  
LAR Hassan
Keyword(s):  
Magnesium Oxide ◽  
Hydrogen Adsorption ◽  
Oxide Surfaces ◽  
Γ Irradiation ◽  
Temperature Range ◽  
Adsorption Of Hydrogen ◽  
Increasing Temperature ◽  
Defect Centres

The adsorption of hydrogen and oxygen on magnesium oxide surfaces with and without the influence of continuous γ-irradiation has been investigated. The temperature range for hydrogen was 294-773 K, and for oxygen 294-973 K. In the absence of radiation little adsorption of oxygen was detected below 573 K, but above this temperature an activated process requiring an Ea of 60.6�5.0 kJ mol-1 was obtained. At all temperatures, continuous γ-irradiation enhanced the adsorption, and a mechanism involving (e-|□-)s defect centres has been proposed. Hydrogen adsorption was detected at all temperatures in the absence of radiation and an enhancement of the uptake was noted during radiation at all temperatures above 294 K. ��� The Gads for oxygen decreased with increasing temperature whilst that for hydrogen increased with temperature. A mechanism for this marked difference has been proposed.

scholarly journals Cell mechanical properties of human breast carcinoma cells depend on temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Aermes ◽  
Alexander Hayn ◽  
Tony Fischer ◽  
Claudia Tanja Mierke
Keyword(s):  
Mechanical Properties ◽  
Power Law ◽  
Cell Mechanics ◽  
Cell Types ◽  
Creep Response ◽  
Temperature Range ◽  
Myosin Filaments ◽  
Cell Mechanical Properties ◽  
Increasing Temperature ◽  
Mcf 7

AbstractThe knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell’s cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.

Influence of Temperature on Hydraulic Conductivity in Compacted Bentonite

1997 ◽  
Vol 506 ◽  
Author(s):  
W. J. Cho ◽  
J. O. Lee ◽  
K. S. Chun
Keyword(s):  
Hydraulic Conductivity ◽  
Influence Of Temperature ◽  
Temperature Range ◽  
Compacted Bentonite ◽  
Influence Of Temperature On ◽  
Water Saturated ◽  
Increasing Temperature ◽  
Good Agreement

ABSTRACTThe hydraulic conductivities in water saturated bentonites at different densities were measured within temperature range of 20 to 80 °C. The results show that the hydraulic conductivities increase with increasing temperature. The hydraulic conductivities of bentonites at the temperature of 80 °C increase up to about 3 times as high as those at 20 °C. The measured values are in good agreement with those predicted. The change in viscosity of water with temperature contributes greatly to increase of hydraulic conductivity.

Plastic Deformation of Mo(Si,Al)2 Single Crystals with the C40 Structure

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Moriwaki ◽  
K. Ito ◽  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
Single Crystals ◽  
Deformation Behavior ◽  
Basal Slip ◽  
Room Temperature ◽  
Slip Systems ◽  
Temperature Range ◽  
Al Content ◽  
Partial Dislocations ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

ABSTRACTThe deformation behavior of single crystals of Mo(Si,Al)2 with the C40 structure has been studied as a function of crystal orientation and Al content in the temperature range from room temperature to 1500°C in compression. Plastic flow is possible only above 1100°C for orientations where slip along <1120> on (0001) is operative and no other slip systems are observed over whole temperature range investigated. The critical resolved shear stress for basal slip decreases rapidly with increasing temperature and the Schmid law is valid. Basal slip appears to occur through a synchroshear mechanism, in which a-dislocations (b=1/3<1120>) dissociate into two synchro-partial dislocations with the identical Burgers vector(b*1/6<1120>) and each synchro-partial further dissociates into two partials on two adjacent planes.

The temperature dependence of the long-range order parameter of Ni3Al

1977 ◽  
Vol 10 (1) ◽  
pp. 14-17 ◽  
Author(s):  
D. P. Pope ◽  
J. L. Garin
Keyword(s):  
Long Range ◽  
Order Parameter ◽  
Anomalous Behavior ◽  
Range Order ◽  
Range Order Parameter ◽  
Long Range Order ◽  
Temperature Range ◽  
Ordered Alloys ◽  
Fine Particle Size ◽  
Increasing Temperature

The macroscopic yield stress of Ni3Al increases rapidly with temperature, reaching a maximum at about 700°C. Such anomalous behavior has been observed in other ordered alloys which undergo partial disordering with increasing temperature, e.g. Cu3Au. The long-range order parameter, S, of stoichiometric Ni3Al powder was measured over the temperature range 25°C to 1000°C and great care was taken to ensure a fine particle size and thus avoid extinction effects. The results of this study showed that, in Ni3Al, S remains constant at about 0.93 over the entire temperature range investigated. This means that theories relating the strength of ordered alloys to S are not applicable to Ni3Al.

THE ALUMINUM REDUCTION OF MAGNESIUM OXIDE: II. THE VAPOR PRESSURE OF MAGNESIUM OVER THE SYSTEM Al–MgO–CaO

1961 ◽  
Vol 39 (11) ◽  
pp. 2290-2294 ◽  
Author(s):  
K. Grjotheim ◽  
O. Herstad ◽  
J. M. Toguri
Keyword(s):  
Vapor Pressure ◽  
Magnesium Oxide ◽  
Equilibrium Pressure ◽  
Aluminum Reduction ◽  
Temperature Range ◽  
Equilibrium Vapor Pressure

The equilibrium vapor pressure of magnesium over the reaction between the calcined dolomite and aluminum was measured by means of the transportation method. In the temperature range 886–1035 °C, the reaction was found to proceed according to the equilibrium[Formula: see text]and the measured equilibrium pressure of magnesium can be expressed by the equation[Formula: see text]

Pzt Interaction with Metal and Oxides Studied by Rutherford Backscattering Spectrometry

1991 ◽  
Vol 243 ◽  
Author(s):  
Peter Revesz ◽  
Jian Li ◽  
Nicholas Szabo ◽  
James W. Mayer ◽  
David Caudillo ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Internal Oxidation ◽  
Rutherford Backscattering Spectrometry ◽  
Metal Electrode ◽  
Rutherford Backscattering ◽  
Annealing Behavior ◽  
Temperature Range ◽  
Pzt Film ◽  
Increasing Temperature

AbstractAnnealing behavior in oxygen ambients of the of the ferroelectric PZT on Hf and Zr electrodes has been studied in the temperature range of 500-800°C using the 3.045MeV O16(∝,∝)O16 resonance in backscattering spectrometry. Internal oxidation of the buried metal electrode was observed. Oxygen concentration of the PZT film decreases with increasing temperature. Pb loss of the PZT film occurred above 700°C.

scholarly journals Catalytic Decomposition of H2O2 over Pure and Li2O-Doped Co3O4 Solids

1998 ◽  
Vol 16 (9) ◽  
pp. 733-746 ◽  
Author(s):  
Gamil A. El-Shobaky ◽  
Nagi R.E. Radwan ◽  
Farouk M. Radwan
Keyword(s):  
Heat Treatment ◽  
Specific Surface ◽  
Catalytic Decomposition ◽  
Nitrogen Adsorption ◽  
Progressive Increase ◽  
Lithium Oxide ◽  
Lithium Nitrate ◽  
Surface Areas ◽  
Catalytically Active ◽  
Cobaltic Oxide

Pure and doped Co3O4 samples were prepared by the thermal decomposition at 500–900°C of pure and lithium nitrate-treated basic cobalt carbonate. The amounts of dopant added were varied in the range 0.75–6 mol% Li2O. The effects of this treatment on the surface and catalytic properties of cobaltic oxide solid were investigated using nitrogen adsorption at −196°C and studies of the decomposition of H2O2 at 30–50°C. The results obtained revealed that Li2O doping of Co3O4 followed by heat treatment at 500°C and 600°C resulted in a progressive increase in the value of the specific surface area, SBET, to an extent proportional to the amount of dopant present. However, the increase was more pronounced in the case of solid samples calcined at 500°C. This increase in the specific surface areas has been attributed to the fixation of a portion of the dopant ions on the uppermost surface layers of the solid leading to outward growth of the surface lattice. The observed increase in SBET due to Li2O doping at 500°C might also result from a narrowing of the pores in the treated solid as a result of the doping process. Lithium oxide doping of cobaltic oxide followed by heat treatment at 700–900°C resulted in a significant decrease in the SBET, Vp and r̄ values. Pure and doped solids precalcined at 500°C and 600°C exhibited extremely high catalytic activities which were not much affected by doping with Li2O. On the other hand, doping followed by calcination at 700–900°C brought about a considerable and progressive increase in the catalytic activity of the treated solids. This treatment did not modify the activation energy of the catalysed reaction, i.e. doping of Co3O4 solid followed by heating at 700°C and 900°C did not alter the mechanism of the catalytic reaction but increased the concentration of catalytically active constituents taking part in the catalytic process without altering their energetic nature.

scholarly journals Experimental Study on Wet Skid Resistance of Asphalt Pavements in Icy Conditions

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1201 ◽  
Author(s):  
Yan ◽  
Mao ◽  
Zhong ◽  
Zhang ◽  
Zhang
Keyword(s):  
Surface Friction ◽  
Melting Process ◽  
Asphalt Pavements ◽  
Skid Resistance ◽  
Ice Melting ◽  
Temperature Range ◽  
Bitumen Emulsion ◽  
Image Measure ◽  
The Difference ◽  
Increasing Temperature

In this research, the durability of skid resistance during the ice melting process with temperature increasing from −5 °C to 10 °C was characterized by means of a British Pendulum Skid Tester. Four types of pavement surfaces were prepared and tested. The difference between two antiskid layers prepared with bitumen emulsion was the aggregate. The detailed angularity and form 2D index of fine aggregates used for antiskid surfaces, characterized by means of the Aggregate Image Measure System (AIMS) with micro image analysis methods, were then correlated with British Pendulum Number (BPN) values. Results indicate that skid resistance has the lowest value during the ice-melting process. The investigated antiskid layers can increase the surface friction during icy seasons. In icy conditions, the skid resistance behavior first worsens until reaches the lowest value, and then increases gradually with increasing temperature. Results from ice-melting conditions on four investigated pavement surfaces give the same temperature range where there will be lowest skid resistance. That temperature range is from 3 °C to 5 °C. A thicker ice layer will result in a lower skid resistance property and smaller “lowest BPN”.

Research on Additives Assisted Catalytic Cyclo-Dehydration of 1, 4-Butanediol to Tetrahydrofuran in Near-Critical Water

2012 ◽  
Vol 550-553 ◽  
pp. 693-698 ◽  
Author(s):  
Yan Yang ◽  
Li Yi Dai ◽  
Jin Shou Wang ◽  
Hong Yan Zhou
Keyword(s):  
Catalytic Activity ◽  
Reaction Mechanism ◽  
Maximum Yield ◽  
Experimental Results ◽  
Time Range ◽  
Temperature Range ◽  
Experimental Parameters ◽  
Increasing Temperature ◽  
Water Ratio

We herein report the cyclo-dehydration of 1,4-butanediol (BD) assisted with additives to form tetrahydrofuran (THF) in near-critical water (NCW).Three additives including Fe2(SO4)3,ZnSO4 and NaHSO4 were screened. Effects of various experimental parameters such as temperature (260-340°C), time (60-180min), reactant/water ratio (r/w, 1:10-1:40) and pressure (15-25MPa) on the yield of THF were examined. Without the presence of additives, the results showed that increasing temperature favored the cyclo-dehydration of BD to form THF. The maximum yield (52.61 wt. %) was obtained at temperature of 340°C and time of 180 min. With the presence of additives, at temperature range of 260~300°C and time range of 60~130min, all the additives selected can promote the cyclo-dehydration of BD to yield THF. However, with further increasing temperature and time, the additives would suppress the formation of THF. The catalytic activity toward the production of THF in the order of Fe2(SO4)3> ZnSO4> NaHSO4. The maximum yield of THF assisted with Fe2(SO4)3 could reach as high as 59.85 wt. % at 320°C, 120 min. Large reactant/water ratio would not benefit the yield of THF because of the dilution of additive. Increasing the pressure will slightly increase the yield of THF. Base on experimental results, a possible reaction mechanism and pathway of dehydration of BD was proposed in NCW.

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