A new fluorescence technique to measure the permeation of water molecules across bilayer membranes

1978 ◽  
Vol 100 (20) ◽  
pp. 6521-6523 ◽  
Author(s):  
Ruediger Lawaczeck
Keyword(s):  
Water Molecules ◽  
Fluorescence Technique ◽  
Bilayer Membranes

scholarly journals Interaction of ions and water in gramicidin A channels: streaming potentials across lipid bilayer membranes.

1978 ◽  
Vol 72 (3) ◽  
pp. 327-340 ◽  
Author(s):  
P A Rosenberg ◽  
A Finkelstein
Keyword(s):  
Osmotic Pressure ◽  
Pressure Difference ◽  
Gramicidin A ◽  
Water Molecules ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Narrow Channels ◽  
Streaming Potentials ◽  
Gramicidin Channel ◽  
Osmotic Pressure Difference

For very narrow channels in which ions and water cannot overtake one another (single-file transport), electrokinetic measurements provide information about the number of water molecules within a channel. Gramicidin A is believed to form such narrow channels in lipid bilayer membranes. In 0.01 and 0.1 M solutions of CsCl, KCL, and NaCl, streaming potentials of 3.0 mV per osmolal osmotic pressure difference (created by urea, glycerol, or glucose) appear across gramicidin A-treated membranes. This implies that there are six to seven water molecules within a gramicidin channel. Electroosmotic experiments, in which the water flux assoicated with current flow across gramicidin-treated membranes is measured, corroborate this result. In 1 M salt solutions, streaming potentials are 2.35 mV per osmolal osmotic pressure difference instead of 3.0 mV. The smaller value may indicate multiple ion occupancy of the gramicidin channel at high salt concentrations. Apparent deviations from ideal cationic selectivity observed while attempting to measure single-salt dilution potentials across gramicidin-treated membranes result from streaming potential effects.

scholarly journals Water permeability of gramicidin A-treated lipid bilayer membranes.

1978 ◽  
Vol 72 (3) ◽  
pp. 341-350 ◽  
Author(s):  
P A Rosenberg ◽  
A Finkelstein
Keyword(s):  
Water Permeability ◽  
Permeability Coefficient ◽  
Pore Radius ◽  
Gramicidin A ◽  
Water Molecules ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Single File ◽  
Water Permeability Coefficient ◽  
Single File Transport

In membranes containing aqueous pores (channels), the osmotic water permeability coefficient, P f, is greater than the diffusive water permeability coefficient, P d. In fact, the magnitude of P f/P d is commonly used to determine pore radius. Although, for membranes studied to date, P f/P d monotonically declines with decreasing pore radius, there is controversy over the value it theoretically assumes when that radius is so small that water molecules cannot overtake one another within the channel (single-file transport). In one view it should equal 1, and in another view it should equal N, the number of water molecules in the pore. Gramicidin A forms, in lipid bilayer membranes, narrow aqueous channels through which single-file transport may occur. For these channels we find that P f/P d approximately 5. In contrast, for the wider nystatin and amphotericin B pores, P f/P d approximately 3. These findings offer experimental support for the view that P f/P d = N for single-file transport, and we therefore conclude that there are approximately five water molecules in a gramicidin A channel. A similar conclusion was reached independently from streaming potential data. Using single-channel conductance data, we calculate the water permeability of an individual gramicidin A channel. In the Appendix we report that there is a wide range of channel sizes and lifetimes in cholesterol-containing membranes.

Utilization of electrical charges in the pores of tofu waste for hydrogen production in water

2020 ◽  
pp. 124-135
Author(s):  
I. N. G. Wardana ◽  
N. Willy Satrio
Keyword(s):  
Magnetic Field ◽  
Hydrogen Production ◽  
Sodium Bicarbonate ◽  
Positive Charge ◽  
Electrical Energy ◽  
Hydrogen Sensor ◽  
Water Molecules ◽  
Partial Charge ◽  
Delocalized Electron ◽  
Water Hydrogen

Tofu is main food in Indonesia and its waste generally pollutes the waters. This study aims to change the waste into energy by utilizing the electric charge in the pores of tofu waste to produce hydrogen in water. The tofu pore is negatively charged and the surface surrounding the pore has a positive charge. The positive and negative electric charges stretch water molecules that have a partial charge. With the addition of a 12V electrical energy during electrolysis, water breaks down into hydrogen. The test was conducted on pre-treated tofu waste suspension using oxalic acid. The hydrogen concentration was measured by a MQ-8 hydrogen sensor. The result shows that the addition of turmeric together with sodium bicarbonate to tofu waste in water, hydrogen production increased more than four times. This is due to the fact that magnetic field generated by delocalized electron in aromatic ring in turmeric energizes all electrons in the pores of tofu waste, in the sodium bicarbonate, and in water that boosts hydrogen production. At the same time the stronger partial charge in natrium bicarbonate shields the hydrogen proton from strong attraction of tofu pores. These two combined effect are very powerful for larger hydrogen production in water by tofu waste.

PEMANFAATAN GLISERIN DARI RESIDU GLISERIN SEBAGAI PLASTICIZER UNTUK PEMBUATAN BIOPLASTIK DENGAN BAHAN BAKU PATI BONGGOL PISANG KEPOK

2017 ◽  
Vol 5 (4) ◽  
pp. 26-32 ◽  
Author(s):  
Azaria Robiana ◽  
M. Yashin Nahar ◽  
Hamidah Harahap
Keyword(s):  
Tensile Strength ◽  
Hydrogen Bonding ◽  
Fatty Acid ◽  
Maximum Yield ◽  
Sem Analysis ◽  
Water Molecules ◽  
Banana Weevil ◽  
Gelatinization Temperature ◽  
Recharge Area ◽  
Maximum Quantity

Glycerin residue is waste oleochemical industry that still contain glycerin. To produce quality and maximum quantity of glycerin, then research the effect of pH acidification using phosphoric acid. Glycerin analysis includes the analysis of pH, Fatty Acid and Ester (FAE), and analysis of the levels of glycerin. The maximum yield obtained at pH acidification 2 is grading 91,60% glycerin and Fatty Acid and Ester (FAE) 3,63 meq/100 g. Glycerin obtained is used as a plasticizer in the manufacture of bioplastics. Manufacture of bioplastics using the method of pouring a solution with varying concentrations of starch banana weevil (5% w/v and 7% w/v), variations of the addition of glycerin (1 ml, 3 ml, 5 ml and 7 ml), and a variety of gelatinization temperature (60°C, 70°C, and 80°C). Analysis of bioplastics include FTIR testing, tensile strength that is supported by SEM analysis. The results obtained in the analysis of FTIR does not form a new cluster on bioplastics starch banana weevil, but only a shift in the recharge area only, it is due to the addition of O-H groups originating from water molecules that enter the polysaccharide through a mechanism gelatinitation that generates interaction hydrogen bonding strengthened. The maximum tensile strength of bioplastics produced at a concentration of starch 7% w/v, 1 ml glycerine and gelatinization temperature of 80°C is 3,430 MPa. While the tensile strength bioplastic decreased with increasing glycerin which can be shown from the results of SEM where there is a crack, indentations and lumps of starch insoluble.

Calculation of Equilibrium Constant for Dimerization of Heavy Water Molecules in Saturated Vapor

2015 ◽  
Vol 60 (3) ◽  
pp. 263-267
Author(s):  
L.A. Bulavin ◽  
◽  
S.V. Khrapatyi ◽  
V.M. Makhlaichuk ◽  
Keyword(s):  
Equilibrium Constant ◽  
Heavy Water ◽  
Saturated Vapor ◽  
Water Molecules

Long-Term Correlations In Diffusive Motion Of Water Molecules And Rare Gas Atoms In Helium And Argon Aqueous Solutions

2015 ◽  
Vol 60 (8) ◽  
pp. 757-763 ◽  
Author(s):  
V.P. Voloshin ◽  
◽  
G.G. Malenkov ◽  
Yu.I. Naberukhin ◽  
◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Rare Gas ◽  
Water Molecules ◽  
Diffusive Motion ◽  
Rare Gas Atoms
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