On rigorous definition of ion transport process and accurate determination of membrane potential at steady state

AIChE Journal ◽  
2019 ◽  
Vol 65 (10) ◽  
Author(s):  
Yuting Sun ◽  
Lianfa Song
Keyword(s):  
Steady State ◽  
Membrane Potential ◽  
Ion Transport ◽  
Transport Process ◽  
Accurate Determination ◽  
Rigorous Definition ◽  
Definition Of

scholarly journals The Influence of the Intracellular Potential on Potassium Uptake by Beetroot Tissue

1966 ◽  
Vol 49 (3) ◽  
pp. 551-563 ◽  
Author(s):  
Ronald J. Poole
Keyword(s):  
Steady State ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Metabolic Activity ◽  
Transport Process ◽  
Equilibrium Potential ◽  
Bicarbonate Concentration ◽  
K Uptake ◽  
Active Transport Process ◽  
Metabolic Transport

Intracellular potentials were measured in beetroot tissue during the steady-state uptake of K+ from various solutions. In solutions containing bicarbonate, the membrane potential becomes up to 70 mv more negative than the estimated equilibrium potential for K+. The uptake of K+ from such solutions is correlated with variations in the potential, both when the bicarbonate concentration is changed and also when the metabolic activity of the tissue is changed by washing in water for various periods. However, the estimated permeability to K+ varies from 0.4 x 10-7 to 1.5 x 10-7 cm·sec-1. It is postulated that the change of potential arises from the metabolic transport of HCO3- into the cell or H+ outwards, and that the associated uptake of K+ is partly or entirely by passive diffusion across the cell membrane. In contrast, K+ uptake from KCl solutions is not accompanied by any significant change in the membrane potential, which remains relatively close to the K+ equilibrium potential. In solutions containing both KHCO3 and KCl, it appears that an amount of K+ equal to the influx of Cl- is taken up independently of the potential, while the component of K+ uptake which is not balanced by Cl- uptake is related to the potential in the manner described. These results suggest that K+ uptake is linked to Cl- uptake in an electrically neutral active transport process.

scholarly journals The watt balance: determination of the Planck constant and redefinition of the kilogram

2011 ◽  
Vol 369 (1953) ◽  
pp. 3936-3953 ◽  
Author(s):  
M. Stock
Keyword(s):  
International System ◽  
Accurate Determination ◽  
Electrical Power ◽  
Planck Constant ◽  
System Of Units ◽  
Macroscopic Quantum Effects ◽  
Watt Balance ◽  
Definition Of ◽  
Base Units

Since 1889, the international prototype of the kilogram has served as the definition of the unit of mass in the International System of Units (SI). It is the last material artefact to define a base unit of the SI, and it influences several other base units. This situation is no longer acceptable in a time of ever-increasing measurement precision. It is therefore planned to redefine the unit of mass by fixing the numerical value of the Planck constant. At the same time three other base units, the ampere, the kelvin and the mole, will be redefined. As a first step, the kilogram redefinition requires a highly accurate determination of the Planck constant in the present SI system, with a relative uncertainty of the order of 1 part in 10 8 . The most promising experiment for this purpose, and for the future realization of the kilogram, is the watt balance. It compares mechanical and electrical power and makes use of two macroscopic quantum effects, thus creating a relationship between a macroscopic mass and the Planck constant. In this paper, the operating principle of watt balance experiments is explained and the existing experiments are reviewed. An overview is given of all available experimental determinations of the Planck constant, and it is shown that further investigation is needed before the redefinition of the kilogram can take place. Independent of this requirement, a consensus has been reached on the form that future definitions of the SI base units will take.

A Method for Determination of Elastohydrodynamic Behavior of Line Shafting Bearings in Their Environment

2007 ◽  
Author(s):  
C. Andreau ◽  
F. Ferdi ◽  
R. Ville ◽  
M. Fillon
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Steady State ◽  
Accurate Determination ◽  
Material Behavior ◽  
Oil Film ◽  
Dynamic Coefficients ◽  
Supporting Line ◽  
Element Method

Safe operation of a rotating line shafting needs to use proper tools and methodology for an accurate determination of its static and steady state behavior in running conditions. Taking into account properly the characteristics of shaft environment is of primary importance. These characteristics are mainly bearing material behavior, oil film dynamic coefficients (stiffness and damping), flexibility and deformations of structure supporting line shafting bearings. Global non linear behavior of the entire system needs to be analyzed to get an accurate solution, as oil film dynamic coefficients depend on steady state location of shaft inside the considered bearing, which depends itself on oil film stiffness, and also on flexibility and deformations of supporting structure. Calculations of structure flexibility and deformations, as well as line shafting stiffness characteristics are performed straightforwardly using finite element method. Solving global matrix equilibrium equation needs to solve elastohydrodynamic (EHD) problem on each bearing. A specific finite element method is developed for this purpose. This method is attractive for taking into account thick and flexible bearing materials such as multi layer synthetic materials. It can also support further developments (effects of geometry defects on bearings, solving thermoelastohydrodynamic problem). The application of the method to the propulsion line shafting of a large LNGC ship (Liquid Natural Gas Carrier) is presented, the final target being the determination of the most optimum bearing offsets for operating safely the vessel in all relevant conditions.

Measurement of the molar mass of the 28Si-enriched silicon crystal (AVO28) with HR-ICP-MS

2015 ◽  
Vol 30 (12) ◽  
pp. 2449-2458 ◽  
Author(s):  
Tongxiang Ren ◽  
Jun Wang ◽  
Tao Zhou ◽  
Hai Lu ◽  
Yuan-jing Zhou
Keyword(s):  
Crucial Role ◽  
Molar Mass ◽  
Mass Measurement ◽  
Accurate Determination ◽  
Silicon Crystal ◽  
Avogadro Constant ◽  
Icp Ms ◽  
Definition Of

Accurate molar mass measurement of the highly 28Si-enriched crystal (AVO28) plays a crucial role in the accurate determination of the Avogadro constant and thus the new definition of the kilogram.

scholarly journals Determination the Corrosion Rate of Carbon Steel (0.4%C) Due to Thermal Cycling, Oil Cooled

2021 ◽  
Vol 65 (1) ◽  
pp. 74-78
Author(s):  
A.S.A. Elmaryami ◽  
Hafied M.B. Khalid ◽  
Abdulhakim Alamaria ◽  
Osama Alashebe ◽  
S.S. Ali ◽  
...  
Keyword(s):  
Steady State ◽  
Carbon Steel ◽  
Corrosion Rate ◽  
Thermal Cycling ◽  
Accurate Determination ◽  
Test Results ◽  
Heating And Cooling ◽  
Steel Bars ◽  
Lower Temperature

The effect of thermal cycling was carried out on steel bars (0.4 C %). A single run was performed at a lower temperature of 32℃ and an upper temperature of 500℃ cooled in water, seawater (previous results) and oil (new results). For several numbers of cycles up to 30 cycles for an accurate determination of heating and cooling times. The effect of thermal cycling on the corrosion rate was evaluated. The effect of thermal cycling on the following properties was evaluated the corrosion rate. The comparison between the effect of thermal cycling on carbon steel (0.4 C %) seawater and water-cooled (previous results as shown in references [1, 2]) and the effect of thermal cycling on carbon steel (0.4 C %) water-cooled (new results) has been studied. From the obtained test results (previous and in this paper, it was found that: the type of corrosion is uniform attack; corrosion rate of the first stage gradually increases with the number of thermal cycling up to 15 cycles, then it takes steady-state up to 30 cycles. It was found that the rate of corrosion (previous results, seawater and water-cooled) is more than the rate of corrosion of the new results, oil-cooled respectively.

scholarly journals Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

2013 ◽  
Vol 57 ◽  
pp. 02005 ◽  
Author(s):  
Benoît Darquié ◽  
Sinda Mejri ◽  
Papa Lat Tabara Sow ◽  
Cyril Lemarchand ◽  
Meriam Triki ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Boltzmann Constant ◽  
Doppler Spectroscopy ◽  
Definition Of The Kelvin ◽  
Definition Of

Accurate determination of minority carrier mobility in silicon from quasi-steady-state photoluminescence

2013 ◽  
Vol 113 (21) ◽  
pp. 213705 ◽  
Author(s):  
J. A. Giesecke ◽  
F. Schindler ◽  
M. Bühler ◽  
M. C. Schubert ◽  
W. Warta
Keyword(s):  
Steady State ◽  
Carrier Mobility ◽  
Minority Carrier ◽  
Accurate Determination ◽  
Quasi Steady State ◽  
Minority Carrier Mobility
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