Search results for "Exchange"
showing 10 items of 2035 documents
Ion-exchange fibers and drugs: an equilibrium study
2001
The purpose of this study was to investigate the mechanisms of drug binding into and drug release from cation-exchange fibers in vitro under equilibrium conditions. Ion-exchange groups of the fibers were weakly drug binding carboxylic acid groups (-COOH), strongly drug binding sulphonic acid groups (-SO(3)H), or combinations thereof. Parameters determining the drug absorption and drug release properties of the fibers were: (i) the lipophilicity of the drug (tacrine and propranolol are lipophilic compounds, nadolol is a relatively hydrophilic molecule), (ii) the ion-exchange capacity of the fibers, which was increased by activating the cation-exchange groups with NaOH, (iii) the ionic streng…
A halocin acting on Na+/H+ exchanger of Haloarchaea as a new type of inhibitor in NHE of mammals
2006
10 páginas, 3 figuras.
Is ABA involved in tolerance responses to salinity by affecting cytoplasm ion homeostasis in rice cell lines?
2012
Abstract The ability of plant cells to maintain cytoplasm ion homeostasis under saline stress is among the main mechanisms involved in salt tolerance. To cope with excess Na + , cells extrude it from the cytoplasm, which requires expenditure of metabolic energy, provided by H + gradients generated by membrane-bound H + -pumps. ABA is well-known to be involved in physiological processes elicited or enhanced by stresses causing cell dehydration. In this work we studied the possible implication of this plant hormone in the control of salt-induced cellular mechanisms conducting to Na + extrusion from the cytoplasm. We used rice ( Oryza sativa L.) cell lines selected for their different toleranc…
Mechanisms of endothelial cell swelling from lactacidosis studied in vitro
2000
One of the early sequelae of ischemia is an increase of circulating lactic acid that occurs in response to anaerobic metabolism. The purpose of the present study was to investigate whether lactic acidosis can induce endothelial swelling in vitro under closely controlled extracellular conditions. Cell volume of suspended cultured bovine aortic endothelial cells was measured by use of an advanced Coulter technique employing the “pulse area analysis” signal-processing technique (CASY1). The isosmotic reduction of pH from 7.4 to 6.8 had no effect on cell volume. Lowering of pH to 6.6, 6.4, or 6.0, however, led to significant, pH-dependent increases of cell volume. Swelling was more pronounced …
Flow cytometric kinetic assay of the activity of Na+/H+ antiporter in mammalian cells.
2004
Background The Na+/H+ exchanger (NHE) of mammalian cells is an integral membrane protein that extrudes H+ ion in exchange for extracellular Na+ and plays a crucial role in the regulation of intracellular pH (pHi). Thus, when pHi is lowered, NHE extrudes protons at a rate depending of pHi that can be expressed as pH units/s. Methods To abolish the activity of other cellular pH-restoring systems, cells were incubated in bicarbonate-free Dulbecco's modified Eagle's medium buffered with HEPES. Flow cytometry was used to determine pHi with 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester or 5-(and-6)-carboxy SNARF-1 acetoxymethyl ester acetate, and the appropriate fluo…
Soft Computing Techniques for Portfolio Selection: Combining SRI with Mean-Variance Goals
2014
A fuzzy portfolio selection model is presented incorporating a socially responsible goal without discarding a priori financially good portfolios or weakening a priori the financial goals. Hence, the optimal portfolios it provides could be either efficient from the strictly financial point of view or non-efficient if leaving the efficient frontier substantially improves the degree of social responsibility. The model can be used to direct heuristic procedures in order to select a reduced number of various alternatives from which the investor can directly make a final decision.
Kultūras diplomātija un starptautiskā akadēmiskā apmaiņa: Erasmus Mundus un Erasmus+ izpēte
2018
Kultūras diplomātija var uzlūkot kā fenomenu dažādos veidos un jomās, taču tādās jomās kā izglītības un akadēmiskajā apmaiņā kultūras diplomātiju var aplūkot sākot no 20. gadsimta 30. gadiem Amerikas Savienotajās Valstīs. Starpvalstu akadēmiskā mobilitāte attīstīijās pateicoties globalizācijai, kā arī pieaugošajai popularitātei, izmantojot starpkultūru praksi kā palīgu politisko interešu īstenošanā. Eiropas Savienība (ES) izveidoja savu akadēmiskās mobilitātes programmu Erasmus Mundus 2003. gadā, kā piemēru ņemot Fulbraita stipendiju programmu Amerikas Savienotajās Valstīs (1946. gads). Erasmus Mundus programmu izveidoja akadēmiskās mobilitātes kanālus ar valstīm, kas nav ES dalībvalstis. Š…
Learning temporal patterns for anomaly intrusion detection
2002
For the last decade an explosive spread of computer systems and computer networks has resulted in a society that is increasingly dependent on information stored on these systems. A computer system connected to the network is accessible from another computer in this network regardless of its geographical position. Along with providing many benefits for legitimate users this technology creates almost unlimited opportunities for malicious persons, which using software vulnerabilities may successfully penetrate the networked computer systems. In order to eliminate potential devastating consequences caused by breaches in computer systems, more and more attention is drawn to the information secur…
Field and laboratory approaches for determining sodicity effects on saturated soil hydraulic conductivity
2006
Abstract Dilution of high-sodicity soil water by low-sodicity rainfall or irrigation water can cause declining soil hydraulic conductivity (K) by inducing swelling, aggregate slaking and clay particle dispersion. Investigations of sodicity-induced reduction in K are generally restricted to repacked laboratory cores of air-dried and sieved soil that are saturated and equilibrated with sodic solution before tests are conducted. This approach may not yield a complete picture of sodicity effects in the field, however, because of loss of antecedent soil structure, small sample size, detachment of the sample from the soil profile, reliance on chemical equilibrium, and differing time scales betwee…
The origin of slow electron recombination processes in dye-sensitized solar cells with alumina barrier coatings
2004
We investigate the effect of a thin alumina coating of nanocrystalline TiO2 films on recombination dynamics of dye-sensitized solar cells. Both coated and uncoated cells were measured by a combination of techniques: transient absorption spectroscopy, electrochemical impedance spectroscopy, and open-circuit voltage decay. It is found that the alumina barrier reduces the recombination of photoinjected electrons to both dye cations and the oxidized redox couple. It is proposed that this observed retardation can be attributed primarily to two effects: almost complete passivation of surface trap states in TiO2 that are able to inject electrons to acceptor species, and slowing down by a factor of…