scholarly journals Electrical potential difference during laser welding

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
H. Zohm ◽  
G. Ambrosy ◽  
K. Lackner
Keyword(s):  
Laser Welding ◽  
Electron Flux ◽  
Electrical Potential ◽  
Potential Drop ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Workpiece Surface ◽  
Voltage Difference ◽  
Contact Points ◽  
Good Agreement

We present a new model for the generation of thermoelectric currents during laser welding, taking into account sheath effects at both contact points as well as the potential drop within the quasi-neutral plasma generated by the laser. We show that the model is in good agreement with experimentally measured electric potential difference between the hot and the cold parts of the welded workpiece. In particular, all three elements of the model are needed to correctly reproduce the sign of the measured voltage difference. The mechanism proposed relies on the temperature dependence of the electron flux from the plasma to the workpiece and hence does not need thermoemission from the workpiece surface to explain the experimentally observed sign and magnitude of the potential drop.

Effects of changes in electrical potential difference on tubular potassium transport

1980 ◽  
Vol 238 (3) ◽  
pp. F235-F246 ◽  
Author(s):  
E. Garcia-Filho ◽  
G. Malnic ◽  
G. Giebisch
Keyword(s):  
Potassium Concentration ◽  
Electrical Potential ◽  
Potential Drop ◽  
Plasma Potassium ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
High Potassium ◽  
Transepithelial Potential ◽  
Wide Range ◽  
Potassium Secretion

To assess directly the role of the transepithelial potential difference (PD) on potassium concentration differences across distal tubular epithelium, continuous and stationary microperfusion experiments were done in tubules voltage-clamped over a wide range of lumen-negative potentials. Potassium was measured either chemically or in situ by potassium-sensitive microelectrodes. Distal cell PD measurements show that most of the potential drop induced by luminal current injection occurred across the luminal cell membrane. Experiments were done in rats either on a control or on a high potassium diet and after amiloride administration. Luminal potassium was highly sensitive to imposed electrical potential changes, attainment of a new steady-state intraluminal potassium concentration was rapid (less than 1 s), and higher luminal potassium concentrations were observed in animals in which potassium secretion had been stimulated. Similar slopes of tubular fluid-to-plasma potassium ratios versus transepithelial potential differences were observed in all experiments. All slopes intersected, at zero PD, at a luminal tubular fluid-to-plasma concentration ratio in excess of unity, indicating the presence of an active component of potassium secretion.

scholarly journals Transmural electrical potential difference in the mammalian esophagus in vivo

1978 ◽  
Vol 75 (2) ◽  
pp. 286-291 ◽  
Author(s):  
Keith S. Turner ◽  
Don W. Powell ◽  
Charles N. Carney ◽  
Roy C. Orlando ◽  
Eugene M. Bozymski
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference

Electrical potential difference between exocelomic fluid and maternal blood in early pregnancy

1998 ◽  
Vol 274 (5) ◽  
pp. R1492-R1495 ◽  
Author(s):  
Stuart Ward ◽  
Eric Jauniaux ◽  
Claire Shannon ◽  
Charles Rodeck ◽  
Robert Boyd ◽  
...  
Keyword(s):  
Electrical Potential ◽  
Extracellular Fluid ◽  
First Trimester ◽  
Maternal Blood ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Amniotic Cavity ◽  
Normal Human ◽  
The Mean ◽  
Forearm Vein

The forces that drive transfer of solutes between maternal blood and embryo in early human pregnancy are poorly understood. The aim of this study was to determine whether there is an electrical potential difference (PD) between maternal blood and the exocelomic cavity and between maternal blood and the amniotic cavity in the normal human conceptus at or before 10 wk of pregnancy. We measured PD between a saline-filled catheter in a forearm vein of women undergoing termination of pregnancy for psychological reasons in the first trimester and a second saline-filled catheter in the exocelomic cavity or amniotic cavity of their conceptus. The mean (±SE) maternal blood/exocelomic cavity PD in eight women was 8.7 ± 1.0 mV and the mean maternal blood/amniotic cavity PD in four of the women was 6.7 ± 1.3 mV, embryo side negative for both sets of measurement. These data show that there is a PD between maternal and embryonic extracellular fluid in the first trimester that will directly influence exchange of ions between the two compartments.

Changes in electrical potential difference of rectal mucosa and of gallbladder bile constituents of dogs fed chenodeoxycholic acid

1986 ◽  
Vol 64 (8) ◽  
pp. 1115-1118
Author(s):  
J. Patrick Shoenut
Keyword(s):  
Chenodeoxycholic Acid ◽  
Dose Group ◽  
Low Dose ◽  
Electrical Potential ◽  
Rectal Mucosa ◽  
Gallbladder Bile ◽  
Potential Difference ◽  
Control Group ◽  
Electrical Potential Difference ◽  
Dissolution Studies

Eighteen dogs were studied for 54 days. Rectal mucosal electrical potential difference (PD), gallbladder bile acids, cholesterol, and phospholipids were measured. It was shown that feeding chenodeoxycholic acid (CDCA) for 24 days in dosages of 15, 30, and 60 mg/kg of body weight, all depressed PD equally but significantly (P < 0.05) in three groups of dogs compared with a control group. This depression was reversible 24 days after CDCA ingestion ceased in the two highest dosages. The low dose group was sacrificed after 24 days of CDCA feeding and the gallbladder bile was analyzed. CDCA and cholesterol were each significantly (P < 0.05) elevated over control values in the gallbladder bile of these dogs. Phospholipids were not significantly changed. The PD, a reflection of Na+–K+ ATPase activity, may be a useful indicator in maximizing dosages of CDCA in gallstone dissolution studies.

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