Effect of Temperature on Punchthrough in Electrical Characteristics of the Plasmalemma of Chara coralinna

1976 ◽  
Vol 3 (6) ◽  
pp. 819
Author(s):  
M.J Beilby ◽  
H.G.L Coster
Keyword(s):  
Steady State ◽  
Elastic Modulus ◽  
Electric Field ◽  
Compressive Stress ◽  
Potential Difference ◽  
Effect Of Temperature ◽  
Electrical Characteristics ◽  
Absolute Value ◽  
A Value ◽  
Increasing Temperature

At the punchthrough, the current required to maintain the hyperpolarized potential difference (p.d.) of the plasmalemma increases very rapidly with increasing hyperpolarization so that, in the steady state, the membrane cannot be hyperpolarized beyond a certain level. It was found that punchthrough in the plasmalemma of C. corallina occurred at more negative (i.e. at greater hyperpolarizing) potentials as the temperature was decreased, from a value of ~ -310mV at T = 32�C to ~ -420 mV at T = 5�C. Some considerations are given to the compressive stress induced in the plasmalemma due to the electric field. These stresses at the p.d. values required for punchthrough are very considerable (~ 3 x 10*6 Nm*-�), and could lead to significant strains in the membrane. The degree of electromechanical compression of the membrane would increase with increasing temperature if, as the evidence cited suggests, the elastic modulus of the membrane decreases with increasing temperature. This would account for the decrease in the absolute value of the p.d. required for punchthrough with increasing temperature.

scholarly journals PREDICTING OPTIMUM PACKAGING CONDITIONS FOR MODIFIED ATMOSPHERE PACKAGES OF TOMATOES

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1161g-1162
Author(s):  
Sannai Gong ◽  
Kenneth A. Corey
Keyword(s):  
Steady State ◽  
Surface Area ◽  
Film Surface ◽  
Gas Diffusion ◽  
Fruit Weight ◽  
Effect Of Temperature ◽  
Modified Atmosphere ◽  
Wide Range ◽  
Input Variables ◽  
Increasing Temperature

Procedures for predicting optimum packaging conditions of modified atmosphere packages (MAP) of tomato (`Heinz 1370') were developed. The relationship between O2 consumption rate and O2 concn (RRo2) was determined using O2 depletion data collected by enclosing tomatoes in jars and sampling head space O2 concn over time. The fitted function was then used in conjunction with other input variables: (1) film permeability to O2 (PO2), (2) film surface area (A), and (3) fruit weight in packages (Wp) to develop the final predictive equation based on Fick's law of gas diffusion. Predictive power of the equation was tested by comparing the steady state O2 concn achieved experimentally with those predicted for a wide range of packaging conditions. Packaging conditions included film surface area, weight of fruit in packages, and O2 permeability of the film (0.0426 and 0.0620 ml/kg hr). Prediction curves showing steady state O2 concn vs. packaging ratio (A/Wp) closely resembled the best fit curves of data. The effect of temperature on steady state O2 concn in MA bags was also examined. Increasing temperature from 20°C to 28±2°C had little effect but decreasing temperature to 10°C led to higher in-package O2 concn. Results indicate that predictive equations can be used to select appropriate films and optimize packaging ratios to achieve desired steady state O2 concn for MAP of tomatoes.

The Effect of Temperature on the Tensile Properties of Steel 0Cr18Ni9

2010 ◽  
Vol 654-656 ◽  
pp. 194-197
Author(s):  
Wei Fen Li ◽  
Wei Niu ◽  
Zhi Ming Hao ◽  
Ming Hai Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Tensile Properties ◽  
Tensile Testing ◽  
Testing Machine ◽  
Effect Of Temperature ◽  
Tensile Testing Machine ◽  
Increasing Temperature

Experiments of tensile mechanical properties of steel 0Cr18Ni9 are done on the MTS 810 tensile testing machine, and the temperature range is from 20°C to 1200°C. The stress vs. strain curves are obtained. Results show that the elastic modulus, yield stress and tensile strength decrease with increasing temperature .Based on the experiment results, the functions of the elastic modulus, yield strength and tensile strength versus temperature are represented by polynomial.

scholarly journals Effect of Temperature on Permeability and Mechanical Characteristics of Lignite

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Jixi Shao ◽  
Yaoqing Hu ◽  
Tao Meng ◽  
Su Song ◽  
Peihua Jin ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Pore Pressure ◽  
Mechanical Characteristics ◽  
Residual Deformation ◽  
Confining Pressure ◽  
Effect Of Temperature ◽  
Accelerated Creep ◽  
Triaxial Creep ◽  
Loading And Unloading ◽  
Increasing Temperature

Underground in situ pyrolysis and gasification is an important method to enable clean utilization of lignite in China. In this study, using the high-temperature triaxial permeability test equipment for different ranges of temperature and pore pressure, the permeability and mechanical characteristics of lignite from the Pingzhuang Mine Area in Chifeng have been examined. The results show that, at constant confining pressure, the elastic modulus of lignite decreases with increasing temperature. For temperature up to approximately 75°C, the elastic modulus is close to the modulus under the uniaxial state. As the temperature increases, the stress-strain curves during loading and unloading are different. The differences between the curves during loading and unloading are greater at higher temperature due to the greater residual deformation. In addition, in different temperature ranges (i.e., 150–650°C), the triaxial creep curves of lignite are different. In particular, at 300–450°C, the triaxial creep curve of lignite alternates between the accelerated creep and the steady creep. Moreover, the permeability change rule in the lignite is complex, and it is governed by the temperature and pore pressure. Hence, for different temperature range and pore pressure, the variations in the permeability are different. In fact, as the temperature increases, the permeability of lignite fluctuates.

scholarly journals Modified-atmosphere Packaging of Blueberry Fruit: Effect of Temperature on Package O2 and CO2

1992 ◽  
Vol 117 (3) ◽  
pp. 436-441 ◽  
Author(s):  
Randolph M. Beaudry ◽  
Arthur C. Cameron ◽  
Ahmad Shirazi ◽  
Diana L. Dostal-Lange
Keyword(s):  
Steady State ◽  
Partial Pressure ◽  
Modified Atmosphere Packaging ◽  
Vaccinium Corymbosum ◽  
Effect Of Temperature ◽  
Modified Atmosphere ◽  
Highbush Blueberry ◽  
Partial Pressures ◽  
Effects Of Temperature ◽  
Increasing Temperature

Highbush blueberry (Vaccinium corymbosum L. `Bluecrop') fruit sealed in low-density polyethylene packages were incubated at 0, 5, 10, 15, 20, or 25C until O2 and CO2 levels in the package reached a steady state. A range of steady-state O2 partial pressures (1 to 18 kPa) was created by placing a range of fruit weights within packages having a constant surface area and film thickness. The steady-state O2 partial pressure in packages containing the same weight of fruit decreased as temperature increased, indicating the respiratory rate rose more rapidly (i.e., had a greater sensitivity to temperature) than O2 transmission through the film. Steady-state O2 and CO2 partial pressures were used to calculate rates of O2 uptake. CO2 Production. and the respiratory quotient (RO). The effects of temperature and 02 partial pressure on O2 uptake and CO2 production and the RQ were characte∼zed. The steady-state O, partial pressure at which the fruit began to exhibit anaerobic CO2 production (the RQ breakpoint) increased with increasing temperature, which implies that blueberry fruit can be stored at lower O2 partial pressures when stored at lower temperatures.

Dielectrophoresis Force and the Electromechanical Responses of Elastomers

2008 ◽  
Vol 54 ◽  
pp. 114-119 ◽  
Author(s):  
Ruksapong Kunanuruksapong ◽  
Anuvat Sirivat
Keyword(s):  
Electric Field ◽  
Storage Modulus ◽  
Yield Point ◽  
Dielectric Constants ◽  
Effect Of Temperature ◽  
Electromechanical Responses ◽  
E 600 ◽  
Increasing Temperature ◽  
Deflection Theory ◽  
Field Strengths

In our research, we investigated the electrorheological responses and dielectrophoresis force of the six elastomers at various electric field strengths and temperatures. For the electrorheological responses, the effect of temperature, between 300 and 370 K, on the storage modulus responses (ΔG′2kV/mm) and on the dielectric constants of elastomers were investigated under applied electric field strengths varying from 0 to 2 kV/mm. The acrylic elastomers (AR70, AR71, and AR72) have positive storage modulus responses and sensitivities with increasing temperature and dielectric constant. In the case of styrene copolymers (SAR, SBS, and SIS), the storage modulus responses and sensitivities increase and attain the maximum at the glass transition temperature of the hard segment. We studied the dielectrophoresis forces of the six elastomers by measured deflection distance under various electric field strengths (0–600 V/mm) and calculated the force from non-linear deflection theory of the cantilever. The results show that the dielectrophoresis forces of the six elastomers increase with increasing electric field strength. The acrylic elastomer AR71 had the lowest electrical yield point (75 V/mm) and it generated the highest force (389 μN at E = 600 V/mm). On the other hand, SIS had highest electrical yield point (400 V/mm) and it generated the lowest force (67 μN at E = 600 V/mm). The dielectrophoresis forces depend on many factors, such as dielectricity, conductivity, and storage modulus of the elastomers.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

High-speed isotachophoresis. Analytical aspects of the steady-state longitudinal temperature profiles

1979 ◽  
Vol 44 (3) ◽  
pp. 841-853 ◽  
Author(s):  
Zbyněk Ryšlavý ◽  
Petr Boček ◽  
Miroslav Deml ◽  
Jaroslav Janák
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Minor Component ◽  
Physical Models ◽  
Temperature Profiles ◽  
Longitudinal Temperature ◽  
Continuous Character

The problem of the longitudinal temperature distribution was solved and the bearing of the temperature profiles on the qualitative characteristics of the zones and on the interpretation of the record of the separation obtained from a universal detector was considered. Two approximative physical models were applied to the solution: in the first model, the temperature dependences of the mobilities are taken into account, the continuous character of the electric field intensity at the boundary being neglected; in the other model, the continuous character of the electric field intensity is allowed for. From a comparison of the two models it follows that in practice, the variations of the mobilities with the temperature are the principal factor affecting the shape of the temperature profiles, the assumption of a discontinuous jump of the electric field intensity at the boundary being a good approximation to the reality. It was deduced theoretically and verified experimentally that the longitudinal profiles can appreciably affect the longitudinal variation of the effective mobilities in the zone, with an infavourable influence upon the qualitative interpretation of the record. Pronounced effects can appear during the analyses of the minor components, where in the corresponding short zone a temperature distribution occurs due to the influence of the temperatures of the neighbouring zones such that the temperature in the zone of interest in fact does not attain a constant value in axial direction. The minor component does not possess the steady-state mobility throughout the zone, which makes the identification of the zone rather difficult.

Research on dynamic characteristics of gear system considering the influence of temperature on material performance

2021 ◽  
pp. 107754632110026
Author(s):  
Zhou Sun ◽  
Siyu Chen ◽  
Xuan Tao ◽  
Zehua Hu
Keyword(s):  
Elastic Modulus ◽  
Dynamic Characteristics ◽  
Poisson’S Ratio ◽  
Gear System ◽  
Poisson's Ratio ◽  
Effect Of Temperature ◽  
Time Varying ◽  
Influence Of Temperature ◽  
Meshing Stiffness ◽  
Influence Of Temperature On

Under high-speed and heavy-load conditions, the influence of temperature on the gear system is extremely important. Basically, the current work on the effect of temperature mostly considers the flash temperature or the overall temperature field to cause expansion at the meshing point and then affects nonlinear factors such as time-varying meshing stiffness, which lead to the deterioration of the dynamic transmission. This work considers the effect of temperature on the material’s elastic modulus and Poisson’s ratio and relates the temperature to the time-varying meshing stiffness. The effects of temperature on the elastic modulus and Poisson’s ratio are expressed as functions and brought into the improved energy method stiffness calculation formula. Then, the dynamic characteristics of the gear system are analyzed. With the bifurcation diagram, phase, Poincaré, and fast Fourier transform plots of the gear system, the influence of temperature on the nonlinear dynamics of the gear system is discussed. The numerical analysis results show that as the temperature increases, the dynamic response of the system in the middle-speed region gradually changes from periodic motion to chaos.

scholarly journals Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

1966 ◽  
Vol 49 (5) ◽  
pp. 989-1005 ◽  
Author(s):  
Richard Fitzhugh
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Giant Axon ◽  
Temperature Curve ◽  
Effect Of Temperature ◽  
Threshold Temperature ◽  
Ionic Conductances ◽  
And Shifts ◽  
The Right ◽  
Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

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