Electron Concentration and Mobility in Semimetallic CdO

1971 ◽  
Vol 49 (4) ◽  
pp. 435-440 ◽  
Author(s):  
F. P. Koffyberg
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Phonon Scattering ◽  
Hall Constant ◽  
Apparent Increase ◽  
Optical Phonon Scattering ◽  
Complete Ionization ◽  
Dominant Process ◽  
Donor States

Measurements of the Hall constant and mobility in the temperature range 81–1100 °K were carried out on n-type CdO single crystals with defect concentrations of 1.9–31.7 × 1018/cm3. Carrier concentrations were found to be independent of temperature, indicating complete ionization of the defect donors and semimetallic conduction. At high temperature the mobility appears to be limited by optical phonon scattering, while at low temperature ionized defect scattering is the dominant process. The apparent increase of the effective mass at low temperatures from 0.15 m0 to 0.45 m0 with increasing defect concentrations is ascribed to increasing nonparabolicity of the conduction band resulting from the addition of donor states to the band.

Relieving of Residual Stresses in Metal Workpieces at High and Low Temperatures

2021 ◽  
Vol 887 ◽  
pp. 651-656
Author(s):  
Marina V. Polonik
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Residual Stresses ◽  
Low Temperatures ◽  
Creep Properties ◽  
Processing Modes ◽  
Properties Of Materials ◽  
High And Low Temperatures ◽  
Temperature Heating ◽  
High Temperature Heating

On the basis of previously accumulated irreversible deformations, and, consequently, residual stresses, the process of removing residual stresses in metal workpieces under the action of low and high temperatures is simulated. Boundary value problems are solved and here are described regularities that are responsible for removing residual stresses for processing modes: high-temperature heating - cooling, high-temperature heating - holding - cooling, low-temperature heating - holding - cooling. The holding stage is modeled, taking into account the creep properties of materials under Norton creep conditions. According to the dependences of the obtained exact solutions, it is shown that it is the holding process that leads to the relaxation of residual stresses.

Environment and Bromoxynil Phytotoxicity

Weed Science ◽  
1986 ◽  
Vol 34 (1) ◽  
pp. 101-105 ◽  
Author(s):  
John D. Nalewaja ◽  
Grzegorz Skrzypczak
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Practical Importance ◽  
Amaranthus Retroflexus ◽  
Controlled Environment ◽  
Growth Stages ◽  
Redroot Pigweed ◽  
Wild Mustard ◽  
Simulated Rain

Experiments in controlled-environment chambers indicated that high temperature, 30 C, increased the phytotoxicity of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) to wild mustard (Sinapis arvensisL. # SINAR) and redroot pigweed (Amaranthus retroflexusL. # AMARE) compared to low temperature, 10 C, during and after treatment. Bromoxynil phytotoxicity generally was higher at relative humidities of 90 to 95% compared to 40 to 60%, but relative humidity had less influence on bromoxynil phytotoxicity than did temperature. A simulated rain immediately after bromoxynil treatment reduced control of both species, but the reduction was of no practical importance for wild mustard. The data indicate that wild mustard and redroot pigweed control would be reduced by bromoxynil application during a period of low temperatures or to plants in advanced growth stages.

Floral Induction in Growing Buds of Lychee (Litchi chinensis) and Mango (Mangifera indica)

1995 ◽  
Vol 22 (5) ◽  
pp. 783 ◽  
Author(s):  
DJ Batten ◽  
CA Mcconchie
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Floral Induction ◽  
Mangifera Indica ◽  
Litchi Chinensis ◽  
Ambient Temperatures ◽  
Potted Plants ◽  
Whole Process ◽  
Experimental Systems

Buds of potted plants of the terminal flowering tree species lychee (Litchi chinensis) and mango (Mangifera indica) forced to begin growth at high temperatures (florally non-inductive) and then transferred to low temperatures produced inflorescences, so the whole process of floral induction can occur in growing buds. Floral initials were visible in lychee within 39 days of transfer to low temperature and 30 days in mango, indicating that floral induction occurs relatively quickly in both species. In most cases where plants were transferred to winter ambient temperatures for floral induction, pre-activated (growing) buds flowered more consistently than buds that were dormant at the time of transfer. If the buds were small when plants were transferred from high temperature to low temperature, leafless inflorescences formed. If buds were a little larger, leafy inflorescences formed, with leaves basally and flowers terminally. If the buds were larger again, the shoots were purely vegetative. All these observations are consistent with floral induction occuning while the bud is growing and provide for much improved experimental systems for studying the physiology of floral induction in species such as lychee and mango.

Peotoemission Study of Si (001) Surfaces Exposed to as Flux

1989 ◽  
Vol 148 ◽  
Author(s):  
H. Okumura ◽  
K. Miki ◽  
K. Sakamoto ◽  
T. Sakamoto ◽  
S. Misawa ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Electronic Structures ◽  
Low Temperatures ◽  
Dimer Model ◽  
Surface And Interface ◽  
High And Low Temperatures ◽  
Interface Structures ◽  
Temperature Sample

ABSTRACTPhotoemission spectra (XPS and UPS) of As-covered Si (001) surfaces prepared at high (>600ºC) and low (<450ºC) temperatures and GaAs epilayers subsequently grown on them were measured without exposing to air. It was found that the surface electronic structures of As/Si prepared at the low temperature are different from those of the high temperature sample, the spectra of which can be interpreted as a symmetric dimer model. Differences were also observed between the GaAs epilayers on the As—covered Si surfaces prepared at the high and low temperatures. The temperature dependence of the surface and interface structures are discussed.

scholarly journals EFFECTS OF LONG-TERM RELATIVELY HIGH AND LOW TEMPERATURE USE ON GROWTH PERFORMANCE AND MEAT QUALITY OF BROILERS

2020 ◽  
pp. 12-17
Author(s):  
Yingying Qiao ◽  
Oleksandr Kyselov ◽  
Changzhong Liu
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Growth Performance ◽  
Meat Quality ◽  
Low Temperatures ◽  
Production Performance ◽  
Control Group ◽  
Temperature Group

The experiment aims to study the effects of long-term relatively high and low temperatures on growth performance and meat quality of broiler chickens. The experiment was carried out in Yunnan Academy of Animal Science, for determine the quality of meat used the laboratories of Henan Institute of Science and Technology. A total of experiment use 240 healthy 1-day-old Avian broiler chickens were randomly divided into three groups: relatively high temperature group, low temperature group and control group. The results of the experiment confirm that at low temperatures, when the energy consumption of the animal decreases, it leads to weight loss, which we can see in the low-temperature group, the average daily weight gain in this experiment was significantly lower than in the control group (P <0.05). It was found that low-temperature stress significantly increased the mortality of broilers, at the age of 42 days in the low-temperature group, the mortality of chickens was higher than in the control group, by 71.4%. Among all evaluated groups on the content of unsaturated fatty acids SFA, PUFA, MUFA and EFA in the muscles of the breasts of broilers, the lowest content was in the lower temperature group than in the control group, by 48.3%, 46.9%, 51.5% and 43.9%. Studies have shown that influence of high-temperature above 30°C causes disturbances in poultry behavior and physiology, leading to reduced production performance. Broilers aged 35-40 days experienced 31°C high-temperature stress and found that their performance and immunity decreased. Broilers feed intake and growth rate at 35°C high temperature were reduced by 13% and 32% than at 20°C. The results showed that: ① Relatively high temperature and low temperature for a long time reduced the growth performance and mortality of broilers, and long-term relatively low temperature decreased the slaughter performance of broilers.② Relatively high and low temperatures for a long period of time reduced the levels of serine, glycine, SFA, PUFA, USFA, EFA and MUFA in broiler breast muscles negative effect on meat quality. ③ The long-term relatively low temperature has a greater adverse effect on broilers than the long-term relatively high temperature. The results provided some theoretical basis for accurately setting the broiler breeding environment temperature, improving broiler quality, maximizing broiler production performance, and increasing the economic benefits of the farm.

scholarly journals Effect of Recycled Shell Waste as a Modifier on the High- and Low-Temperature Rheological Properties of Asphalt

2021 ◽  
Vol 13 (18) ◽  
pp. 10271
Author(s):  
Yuchen Guo ◽  
Xuancang Wang ◽  
Guanyu Ji ◽  
Yi Zhang ◽  
Hao Su ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Rheological Properties ◽  
Low Temperatures ◽  
High Speed ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Modified Asphalt ◽  
Temperature Performance

The deteriorating ecological environment and the concept of sustainable development have highlighted the importance of waste reuse. This article investigates the performance changes resulting from the incorporation of shellac into asphalt binders. Seashell powder-modified asphalt was prepared with 5%, 10%, and 15% admixture using the high-speed shear method. The microstructure of the seashell powder was observed by scanning electron microscope test (SEM); the physical-phase analysis of the seashell powder was carried out using an X-ray diffraction (XRD) test; the surface characteristics and pore structure of shellac were analyzed by the specific surface area Brunauer-Emmett-Teller (BET) test; and Fourier infrared spectroscopy (FTIR) qualitatively analyzed the composition and changes of functional groups of seashell powder-modified asphalt. The conventional performance index of seashell powder asphalt was analyzed by penetration, softening point, and ductility (5 °C) tests; the effect of seashell powder on asphalt binder was studied using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR) at high and low temperatures, respectively. The results indicate the following: seashell powder is a coarse, porous, and angular CaCO3 bio-material; seashell powder and the asphalt binder represent a stable physical mixture of modified properties; seashell powder improves the consistency, hardness, and high-temperature performance of the asphalt binder but weakens the low-temperature performance of it; seashell powder enhances the elasticity, recovery performance, and permanent deformation resistance of asphalt binders and improves high-temperature rheological properties; finally, seashell powder has a minimal effect on the crack resistance of asphalt binders at very low temperatures. In summary, the use of waste seashells for recycling as bio-modifiers for asphalt binders is a practical approach.

Dislocations at low temperatures in brittle ceramics

1986 ◽  
Vol 44 ◽  
pp. 504-507
Author(s):  
P. Veyssière ◽  
J. Castaing
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Ceramic Materials ◽  
Dislocation Climb ◽  
Atomic Diffusion ◽  
Macroscopic Strain ◽  
Rocksalt Structure ◽  
Matter Transport

Brittleness is a feature common to many ceramic materials at low temperature. However, in some cases, they remain ductile as, for instance, crystals with the rocksalt structure which can be deformed down to 4.2 K: their properties are very similar to those of metals and will not be described in the present paper (for a review, see). Usually, macroscopic strain can be obtained only at temperatures larger than 0.5 TM, where TM is the melting temperature. The resulting microstructures consist in networks where dislocation climb is shown by TEM to have played an extensive role. Nevertheless, despite the active atomic diffusion pointed out in the high temperature experiments, what controls the transition between ductility and brittleness is probably not related to the rate of matter transport. Rather, the reasons for this transition rely on crystal structure and chemical bonding, which are of prime importance in the choice of Burgers vectors and slip plane, in the mobility of dislocations...

The Difference in Optics Between Volcanic and Plutonic Plagioclases, and its Bearing on the Granite Problem

1952 ◽  
Vol 89 (4) ◽  
pp. 233-250 ◽  
Author(s):  
Doris L. Reynolds
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Metamorphic Rock ◽  
Alkali Feldspar ◽  
Optical Indicatrix ◽  
Quartz Porphyry ◽  
The Real ◽  
Magmatic Rocks ◽  
The Difference

AbstractThe orientation of the optical indicatrix in synthetic and volcanic plagioclases differs from that in plutonic and metamorphic plagioclases, the former “optics” being commonly known as “high-temperature”, and the latter as “low-temperature”. The difference between the two series is most marked at the sodic end and decreases towards An70. The conclusion that the difference, though small, still persists in the range An70 to An100 is shown to be unwarranted on the evidence available. Grave doubt is thrown on the supposition that temperature is the controlling factor in determining the type of optics by Tuttle and Bowen's failure to synthesize low-temperature albite, even at low temperatures. It is known, however, that some low-temperature plagioclases (e.g. in albite-schists) have grown without the intervention of melt. The real antithesis may therefore be between plagioclases crystallized from melts, and those developed during the metamorphic reconstitution of rocks.From the fact that the plagioclase, quartz, and alkali feldspar of undoubted magmatic rocks such as quartz-porphyry and rhyolite are respectively systematically different from those of granite it is concluded that the latter is a metamorphic rock

Evidence of Tunneling in n-4H-SiC/SiO2 Capacitors at Low Temperatures

2013 ◽  
Vol 740-742 ◽  
pp. 557-560 ◽  
Author(s):  
Lucian Dragos Filip ◽  
Ioana Pintilie ◽  
Bengt Gunnar Svensson
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Resonant Tunneling ◽  
Electron Tunneling ◽  
Energy Levels ◽  
Neutral Donor ◽  
Capacitance Voltage ◽  
Probe Frequency ◽  
Resonant Electron ◽  
Donor States

In this work, anomalous discontinuities observed in Capacitance-Voltage (C-V) characteristics on non-nitridated n-4H-SiC/SiO2 capacitors at low temperature are addressed. The appearance of abrupt capacitance minima, always at the same gate voltages (4V and 8V) and independent on probe frequency, led us to consider a resonant electron tunneling process from neutral donor states present at the SiC/SiO2 interface into two well defined energy levels in the oxide layer. Results of numerical simulations based on this model describe quantitatively the experimentally observed discontinuities at 4V and 8V and provide strong evidence for the presence resonant tunneling.

scholarly journals HIGH AND LOW TEMPERATURE BEHAVIOR OF A QUANTUM GROUP FERMION GAS

1996 ◽  
Vol 11 (29) ◽  
pp. 2325-2333 ◽  
Author(s):  
MARCELO R. UBRIACO
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Quantum Group ◽  
Upper Bound ◽  
Low Temperatures ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Temperature Behavior ◽  
Spatial Dimensions ◽  
Fermion Gas

We consider the simplest SU q(2) invariant fermionic Hamiltonian and calculate the low and high temperature behavior for the two distinct cases q>1 and q<1. For low temperatures we find that entropy values for the Fermi case are an upper bound for those corresponding to q≠1. At high temperatures we find that the sign of the second virial coefficient depends on q, and vanishes at q=1.96. An important consequence of this fact is that the parameter q connects the fermionic and bosonic regions, showing therefore that SU q(2) fermions exhibit fractional statistics in three spatial dimensions.

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