基于Comsol的稀土熔盐电解槽电场分析

采用Comsol Multiphysics 有限元软件,基于麦克斯韦原理,在电流不变的情况下,研究建立3 kA稀土钕熔盐电解槽电场数学模型,考察电极插入深度和极距对槽电压、电流密度等电场特征的影响。结果表明,模拟结果与实际生产数据吻合度高,所建立模型能较好地反映钕熔盐电解生产实际;随着电极插入深度的增大和极距的缩短,电解槽电压下降,利于降低电能消耗,但阴极电流密度比阳极电流密度下降快,不利于电流效率提高。应综合考虑能耗和效率,合理调整电极插入深度和极距,以降低钕熔盐电解单位能耗。     

Influence of an electric field on the plastic deformation of fine-grained Al2O3

The influence of an electric field E = 300 V/cm on the plastic deformation at 1450 °C to 1600 °C of fine-grained alumina with ∼300 ppm MgO and d _o=1.4 to 2.5 μm was investigated. After removal of the effect of Joule heating, the field reduced the flow stress by ∼4 MPa relatively independent of temperature, representing a 25 to 70 pct reduction in the flow stress. The field had no effect on the stress exponent n=2.2, nor on the grain size exponent p=1.9. It did however have an appreciable effect on the combined constant AD _o of the Weertman-Dorn equation and the activation energy Q. The latter increased from 492 kJ/mole without the field (typically that for Al³⁺ ion lattice diffusion) to 880 to 1070 kJ/mole with the field, which is more typical of sub-boundary or grain boundary diffusion of either Al³⁺ or O²⁻-ions in alumina. It therefore appears that the field changed the rate-controlling, grain boundary sliding accommodation mechanism from the lattice diffusion of Al³⁺ ions to either sub-boundary or grain boundary diffusion of Al³⁺ or O²⁻-ions. The electric field caused isotropic swelling of the specimen when applied for an extended period of time without application of stress. Pores responsible for the swelling occurred along the grain boundaries. They may have resulted from electrotransport of Al³⁺ ions, leaving behind an Al-deficient layer from which free oxygen bubbles formed along the grain boundaries. Electric field-enhanced gas reactions at the pores may have also contributed to the swelling. It is proposed that swelling due to electrotransport may possibly be avoided by the addition of solutes, which increase the electronic or oxygen ion conductivity transference numbers compared to the aluminum ions.     

Cochlear outer hair cell bending in an external electric field

We have used a high-resolution motion analysis system to reinvestigate shape changes in isolated guinea pig cochlear outer hair cells (OHCs) evoked by low-frequency (2-3 Hz) external electric stimulation. This phenomenon of electromotility is presumed to result from voltage-dependent structural changes in the lateral plasma membrane of the OHC. In addition to well-known longitudinal movements, OHCs were found to display bending movements when the alternating external electric field gradients were oriented perpendicular to the cylindrical cell body. The peak-to-peak amplitude of the bending movement was found to be as large as 0.7 microm. The specific sulfhydryl reagents, p-chloromercuriphenylsulfonic acid and p-hydroxymercuriphenylsulfonic acid, that suppress electrically evoked longitudinal OHCs movements, also inhibit the bending movements, indicating that these two movements share the same underlying mechanism. The OHC bending is likely to result from an electrical charge separation that produces depolarization of the lateral plasma membrane on one side of the cell and hyperpolarization on the other side. In the cochlea, OHC bending could produce radial distortions in the sensory epithelium and influence the micromechanics of the organ of Corti.     

液膜乳化液的离心-脉冲电场连续破乳

在分析离心一脉冲电场连续破乳原理的基础上,设计和制作了竖式圆柱绝缘电极实验室用的离心-脉冲电场连续破乳器.在M6401-L113B-煤油-H₂SO₄和Lix984N-L113A-煤油- H₂SO₄乳化液膜体系处理含Cu²⁺废水的实验中,研究了离心-脉冲电场连续破乳时的各种影响因素.结果表明,离心-脉冲电场能有效地对上述乳化液膜体系进行连续破乳,且其破乳效果比单一脉冲电场连续破乳效果要好.     

Simulation of the electric field in an electrolytic cell with a liquid metal anode

The influence of the temperature and the level of liquid metal electrodes on the direct current distribution over the surface of the liquid metal anode and the electrolyte KCl-PbCl₂ volume in a cylindrical electrolytic cell is studied by simulating the electric field.     

Classification of powders in the electric field

Translated from Poroshkovaya Metallurgiya, No. 12, pp. 10–14, December, 1990.     

Tumor promotion in a breast cancer model by exposure to a weak alternating magnetic field

In view of the methodological problems of epidemiological studies on associations between exposures to 50/60 Hz magnetic fields (MF) and increased incidence of cancers, laboratory studies are necessary to determine if 50/60 Hz MF are cancer promoters or can progress cancers. The objective of the present study was to determine if an alternating MF of low flux density exerts tumor-promoting or co-promoting effects in a model of breast cancer in female rats. Mammary tumors were induced by the chemical carcinogen 7,12-dimethylbenz(a)anthracene (DMBA). A group of 99 rats was exposed to a homogeneous MF of 50 Hz, 100 microT (microtesla), for 24 h/day 7 day/week for a period of 91 days; another group of 99 rats was sham-exposed under the same environmental conditions as the MF-exposed rats. The exposure chambers were identical for MF-exposed and sham-exposed animals. DMBA was administered orally at a dose of 5 mg/kg at the first day of exposure and at weekly intervals thereafter up to a total dose of 20 mg per rat. The animals were palpated once weekly to assess the development of mammary tumors. In controls, DMBA induced tumors in about 40% of the animals within three months of first application. Eight weeks after DMBA application the MF-exposed rats exhibited significantly more tumors than sham-exposed animals. This difference in the rate of tumor development was observed throughout the period of exposure. At the end of the three-month period of MF exposure the tumor incidence in MF-exposed rats was 50% higher than in sham-exposed rats, the difference being statistically significant. Furthermore, the size of tumors as estimated by palpation was significantly larger in the MF-exposed compared to sham-exposed rats. The data demonstrates that long-term exposure of DMBA-treated female rats to an alternating MF of low flux density promotes the growth and increases the incidence of mammary tumors, thus strongly indicating that MF exposure exerts tumor-promoting and/or copromoting effects.     

Deformation and morphogenesis of Acetabularia cell membrane. I. Relation of deformation to genetic and geometric factors

Relationships between the changes of geometric shape, volume and deformations of the apical growth part of acetabularia cell are studied. Jung module E approximately 25 kg/cm2, viscosity coefficient of the apex cell theta 4 - 10(4) kg-sec/cm2 and intracellular pressure P approximately 1 kg/cm2 are measured. Cell shape formation according to Waddington is concerned with simple physical factors which are under the genetic control. It is shown that uneven deformations with the loss of shape stability bring about periodic cell complications.     

Mediated short-term influence of alternating magnetic field on the epileptic brain

The changes of bioelectric activity of the brain hemispheres were studied under the influence of an alternating magnetic field (AMF), directed on the hand of 20 epileptic patients and 18 healthy normals. Under AMF influence there was intensification of epileptic activity--elevation of the focal bioelectric characteristics and of the processes of generalization. It permitted to apply AMF for diagnosis of epileptic focus. Under AMF influence more stable changes in posterio-parietal areas of the right hemisphere occur. The authors came to the conclusion that AMF effects were mainly realized with participation of right hemisphere.     

A mathematical model of the elastoplastic mechanism of deformation of porous sintered materials. II. A generalized rheological model of deformation of porous materials

Translated from Poroshkovaya Metallurgiya, No. 12 (360), pp. 1–10, December, 1992.     

Apolipoprotein-mediated plasma membrane microsolubilization. Role of lipid affinity and membrane penetration in the efflux of cellular cholesterol and phospholipid

Lipid-free apolipoprotein (apo) A-I contributes to the reverse transport of cholesterol from the periphery to the liver by solubilizing plasma membrane phospholipid and cholesterol. The features of the apolipoprotein required for this process are not understood and are addressed in the current study. Membrane microsolubilization of human fibroblasts is not specific for apo A-I; unlipidated apos A-II, C, and E incubated with the fibroblast monolayers at a saturating concentration of 50 micrograms/ml are all able to release cholesterol and phospholipid similarly. To determine the properties of the apolipoprotein that drive the process, apo A-I peptides spanning the entire sequence of the protein were utilized; the peptides correspond to the 11- and 22-residue amphipathic alpha-helical segments, as well as adjacent combinations of the helices. Of the 20 helical peptides examined, only peptides representing the N-and C-terminal portions of the protein had the ability to solubilize phospholipid and cholesterol. Cholesterol efflux to the most effective peptides, 44-65 and 209-241, was approximately 50 and 70%, respectively, of that to intact apo A-I. Deletion mutants of apo E and apo A-I were constructed that have reduced lipid binding affinities as compared with the intact molecule. The proteins, apo A-I (Delta222-243), apo A-I (Delta190-243), apo E3 (Delta192-299) and apo E4 (Delta192-299) all exhibited a decreased ability to remove cellular cholesterol and phospholipid. These decreases correlated with the reduced ability of these proteins to penetrate into a phospholipid monomolecular film. Overall, the results indicate that insertion of amphipathic alpha-helices between the plasma membrane phospholipid molecules is a required step in the mechanism of apolipoprotein-mediated cellular lipid efflux. Therefore the lipid binding ability of the apolipoprotein is critical for efficient membrane microsolubilization.