Size-dependent compensation effect and negative magnetization in Co(Cr0.9Fe0.1)2O4 annealed at different temperatures

2022 ◽  
pp. 163692
Author(s):  
Y. Qiu ◽  
S.S. Zheng ◽  
C.L. Li ◽  
G.O. Barasa ◽  
M.L. Chen ◽  
...  
Keyword(s):  
Compensation Effect ◽  
Size Dependent ◽  
Different Temperatures ◽  
Negative Magnetization

Kinetics of Ion-Pair Effect of Aquation of Bromopentaammine Cobalt(III) Complex in Different Dicarboxylate Media

2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Compensation Effect ◽  
Ion Pairing ◽  
Reaction Rates ◽  
Ion Pair ◽  
Free Energy Of Activation ◽  
Different Types ◽  
Different Temperatures ◽  
Kinetics Of

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.

ACOUSTICAL CHARACTERIZATION OF NANOSTRUCTURED METAL

2008 ◽  
Vol 07 (06) ◽  
pp. 315-323
Author(s):  
R. K. SINGH ◽  
R. P. SINGH ◽  
M. P. SINGH
Keyword(s):  
Nearest Neighbor ◽  
Ultrasonic Attenuation ◽  
Phonon Interaction ◽  
Size Dependent ◽  
Third Order Elastic Constants ◽  
Longitudinal And Shear Waves ◽  
Shear Modes ◽  
Different Temperatures ◽  
Experimental Values ◽  
Edge Dislocations

Ultrasonic attenuation due to phonon–phonon interaction, thermoelastic loss and dislocation damping arising from screw and edge dislocations has been evaluated in nanocrystalline copper (13 nm) in the temperature range 50–500 K, and size-dependent attenuation at a constant temperature for longitudinal and shear modes of propagation. Second and third order elastic constants have been obtained, taking the nearest neighbor distance and the hardness parameter as input data. SOEC and TOEC (obtained at different temperatures) have been used to obtain Grüneisen parameters and nonlinearity parameters, which in turn have been used to evaluate α/f2 for longitudinal and shear waves. Results have been discussed, and compared with available experimental values. It has been found that α/f2 increases with temperature and a significant contribution to the total attenuation occurs due to scattering from grain boundaries, and ultrasonic attenuation due to thermoelastic loss is negligible compared to phonon–phonon interaction, establishing that the major part of energy from the sound wave is removed owing to the interaction of acoustic phonons with thermal phonons (lattice vibrations).

Effects of Exogenous SA and H2O2 on Wheat-Seedling�s Antioxidant Enzymes in Different Temperatures

2020 ◽  
Vol 71 (6) ◽  
pp. 500-507
Author(s):  
Baoting Fang ◽  
Xiangdong Li ◽  
Simeng Du ◽  
Yunhui Shao ◽  
Hanfang Wang ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
Compensation Effect ◽  
Wheat Seedling ◽  
Proline Content ◽  
Climate Chamber ◽  
H2o2 Treatment ◽  
Wheat Growth ◽  
Wheat Seedlings ◽  
Different Temperatures ◽  
Exogenous Salicylic Acid

In order to clarify the compensation effect of exogenous salicylic acid (SA) and H2O2 on wheat growth, this paper, by setting different growth temperatures in the artificial climate chamber, has studied the effects of antioxidant enzymes and proline content of wheat seedlings with spraying SA, hydrogen peroxide (H2O2) and SA+H2O2. The results show that catalase (CAT) activity, in 0 and 5 �C is lower than 10 and 15 �C, while the peroxidase (POD) activity is opposite. The activity of ascorbate peroxidase (APX) increases gradually with temperature increasing. Exogenous SA, H2O2, and SA+H2O2 could effectively improve the activity of wheat antioxidant enzymes and the content of proline (Pro), while the SA+H2O2 treatment improves obviously.

Influence of temperature on size-dependent predation by a fish (Gasterosteus aculeatus) and a jellyfish (Aurelia aurita) on larval capelin (Mallotus villosus)

1997 ◽  
Vol 54 (12) ◽  
pp. 2759-2766 ◽  
Author(s):  
J K Elliott ◽  
W C Leggett
Keyword(s):  
Gasterosteus Aculeatus ◽  
Aurelia Aurita ◽  
Mallotus Villosus ◽  
Selective Predation ◽  
Moon Jellyfish ◽  
Predator Prey ◽  
Size Dependent ◽  
Capelin Mallotus Villosus ◽  
Different Temperatures ◽  
Influence Of Temperature On

We compared the size-dependent mortality patterns of newly emerged larval capelin (Mallotus villosus) at three different temperatures (3, 9, and 15°C) when exposed to predation by threespine stickleback (Gasterosteus aculeatus) and moon jellyfish (Aurelia aurita). Controlled experiments were conducted in both microcosms (38 L) and mesocosms (3100 L). Some temperature-related trends were evident in experiments with sticklebacks, but not with jellyfish. Sticklebacks fed selectively on smaller capelin larvae at 15°C, were nonselective at 9°C, and fed on larger larvae at 3°C. There was no prey size selection by A. aurita at any of the temperatures examined. Our findings support the view that the direction and magnitude of size-selective predation vary depending on the predator-prey assemblage and environmental conditions examined.

Particle Size Dependent Structural and Magnetic Properties of CoCrFeO4 Nanoparticles

2012 ◽  
Vol 486 ◽  
pp. 129-133
Author(s):  
R. Mane Dhanraj ◽  
H. Kadam Ram ◽  
T. Alone Suresh ◽  
E. Shirsath Sagar
Keyword(s):  
Particle Size ◽  
Sintering Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Blocking Temperature ◽  
Particle Sizes ◽  
Particle Size Range ◽  
Size Dependent ◽  
Auto Combustion ◽  
Different Temperatures

Nanoparticles of CoCrFeO4ferrite in the particle size range of 9 - 38 nm have been prepared by a sol-gel auto combustion method. Synthesized powders were annealed at four different temperatures viz. 400 °C, 600 °C, 800 °C and 1000 °C. Particle sizes are determined by X-ray analysis and TEM. The size of the nanoparticles increase linearly with sintering temperature and time, most probably due to coalescence that increases as sintering temperature increases. The saturation magnetization increases from 62 to 81 emu/g and coercivity initially increases up to 814 Oe and then decreases to 366 Oe with increase in particle size and sintering temperature. The typical blocking temperature increases from 135 to 165 K with increasing particle size.

Production and STEM examination of controlled-size silver clusters

1983 ◽  
Vol 41 ◽  
pp. 338-339
Author(s):  
M. A. Listvan ◽  
R. P. Andres
Keyword(s):  
Cluster Size ◽  
Metal Clusters ◽  
Experimental Parameter ◽  
Carbon Films ◽  
Metal Species ◽  
Silver Clusters ◽  
Free Jet ◽  
Size Dependent ◽  
Cluster Properties ◽  
Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

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