Irreversible thermodynamic model equations of the transport across a horizontally mounted membrane

The Kedem-Katchalsky-Zelman model equations for transmembrane transport in multicomponent, non-ionic and heterogeneous solutions have been modified. The validity of this model for binary and ternary solutions was verified, using a cell with a horizontally mounted membrane. In the cell, volume and solute fluxes were measured as a function of gravitational configuration. In the experimental set-up, water was placed on one side of the membrane. The opposite side of the membrane was exposed to aqueous solutions of densities greater than that of water, aqueous ethanol (less dense than water) or glucose/ethanol/water solutions. The experimental results presented herein illustrate pseudo-phase transitions which occur from a non-convectional to convectional state or in the reverse direction.

Impact of Anesthesia on the Outcome of Acute Ischemic Stroke after Endovascular Treatment with the Solitaire Stent Retriever

BACKGROUND AND PURPOSE

General anesthesia during endovascular treatment of acute ischemic stroke may have an adverse effect on outcome compared with conscious sedation. The aim of this study was to examine the impact of the type of anesthesia on the outcome of patients with acute ischemic stroke treated with the Solitaire stent retriever, accounting for confounding factors.

MATERIALS AND METHODS

Four-hundred one patients with consecutive acute anterior circulation stroke treated with a Solitaire stent retriever were included in this prospective analysis. Outcome was assessed after 3 months by the modified Rankin Scale.

RESULTS

One-hundred thirty-five patients (31%) underwent endovascular treatment with conscious sedation, and 266 patients (69%), with general anesthesia. Patients under general anesthesia had higher NIHSS scores on admission (17 versus 13, P < .001) and more internal carotid artery occlusions (44.6% versus 14.8%, P < .001) than patients under conscious sedation. Other baseline characteristics such as time from symptom onset to the start of endovascular treatment did not differ. Favorable outcome (mRS 0-2) was more frequent with conscious sedation (47.4% versus 32%; OR, 0.773; 95% CI, 0.646-0.925; P = .002) in univariable but not multivariable logistic regression analysis (P = .629). Mortality did not differ (P = .077). Independent predictors of outcome were age (OR, 0.95; 95% CI, 0.933-0.969; P < .001), NIHSS score (OR, 0.894; 95% CI, 0.855-0.933; P < .001), time from symptom onset to the start of endovascular treatment (OR, 0.998; 95% CI, 0.996-0.999; P = .011), diabetes mellitus (OR, 0.544; 95% CI, 0.305-0.927; P = .04), and symptomatic intracerebral hemorrhage (OR, 0.109; 95% CI, 0.028-0.428; P = .002).

CONCLUSIONS

In this single-center study, the anesthetic management during stent retriever thrombectomy with general anesthesia or conscious sedation had no impact on the outcome of patients with large-vessel occlusion in the anterior circulation.

Evolution of concentration field in a membrane system

This paper deals with the evolution of concentration field at a single membrane system. Concentration field evolution is described by concentration effect of stable boundary layers, which originate in this system. The concentration effect of boundary layers (CBLE) is studied experimentally on the basis concentration profiles obtained from computer analysis of interferometric pictures of near-membrane regions. Besides experimental results, we also report theoretical investigations and numerical calculations of this effect for two models of membranes (an infinite thin wall and the wall of thickness l). Evolution of concentration field at different distances from membrane surface describes accurately the spatio-temporal structure of the concentration boundary layers (CBLs). Results have shown that their spatial structure is fully established and these layers develop diffusively.

Modification of the Kedem-Katchalsky equations

The presented modification of the transport equations of Kedem-Katchalsky resulted in the introduction of (omega s/omega) and omega/(omega-Lp sigma[(1-sigma)C1-(1-sigma s)C2]) factors into the Kedem-Katchalsky equations. The above factors determine the influence of boundary layers on transport across the membrane. The modified Kedem-Katchalsky equations were verified for synthetic membranes and it was shown that the value of the (omega s/omega) factor depended on the type of membrane and the membrane configuration system. This modification facilitated a wider range of application of the Kedem-Katchalsky equations to systems in which the solutions were stirred or unstirred.

A model equation for the gravielectric effect in electrochemical cells

The gravielectric effect model equation for a single-membrane system was elaborated. This model for binary and ternary ionic solutions was verified using a cell with a horizontally mounted membrane. In this cell, the membrane and transition potentials were measured as a function of gravitational configuration. In these experiments, a 0.001 M aqueous solution of sodium chloride was placed on one side of the membrane. The opposite side of the membrane was exposed to either aqueous sodium chloride solutions, with densities greater than that of 0.001 M aqueous NaCl, or ethanol/NaCl/water solutions. On the basis of the experimental results, the influence of constrained release and the gravielectric effect were established. These experimental findings are interpreted in terms of a convective gravitational instability that reduces boundary layer dimensions and increases the permeability coefficient of the complex system: boundary layer/membrane/boundary layer. A concentration-gradient Rayleigh number is used in a mathematical model for gravitationally sensitive membrane potential.

Second order optical effects in Au nanoparticle-deposited ZnO nanocrystallite films

Photoinduced second harmonic generation (SHG) in Au nanoparticle-deposited ZnO nanocrystallite (NC) films was explored by applying bicolor coherent treatment of a Nd-YAG laser with wavelength 1.06 µm and its SHG. We have established that coexistence of the ZnO and Au nanoparticles gives a substantially larger SHG output with respect to pure ZnO NC deposited on the glass substrate. It was established that the value of the second order susceptibility is about 23 pm V(-1). Better nonlinear optical susceptibilities were obtained during phototreatment at temperatures near 30-35 °C for the Au doped samples. The samples without gold NCs are temperature independent. Generally an increasing temperature leads to a decrease of the optical SHG.

Application of various power densities of ultrasound in the treatment of leg ulcers

AIM

The objective of our study was to determine which ultrasound power density (0.5 W/cm(2) or 1 W/cm(2)) is more effective at reducing the area and volume of leg ulceration.

METHODS

A total of 65 patients with venous ulcers were randomly divided into three groups: A, B and C. In group A, 22 patients were treated with ultrasound rated at 1 W/cm(2) and with compressive therapy. In group B, 21 patients were treated with ultrasound rated at 0.5 W/cm(2) and with compressive therapy. In both groups the patients were treated with a pulsed wave of a duty cycle of 1/5 (impulse time=2 ms, pause time=8 ms) and frequency of 1 MHz. The 22 patients in group C (control group) were subjected to topical pharmacological treatment.

RESULTS

We found a statistically significant reduction of the ulcer area, volume and linear dimensions in all three groups of patients. The ulcer area reduction rate was highest in group B. The volume reduction rate in group B was higher than in group A only. The rate of reduction of suppurate area was highest in group B.

CONCLUSION

We have demonstrated that ultrasound rated at 0.5 W/cm(2) causes greater and faster changes in the healing process than ultrasound rated at 1 W/cm(2).

A model equations of the volume transport of multicomponent and heterogeneous non-ionic solutions in double-membrane system

The volume flows model equation for a double-membrane system, in which two membranes separate three compartments (l,m,r) containing the heterogeneous, non-ionic n-component solutions is elaborated. In this system the solution concentrations fulfill the condition Clk > Cmk > Crk. The inter-membrane compartment (m) consists of the infinitesimal layer of solution. The volume of compartment m and external compartments (l and r) fulfill the conditions Vm→ 0 and Vl =Vr→∞ respectively. The linear dependences of the volume flux on concentration differences in binary solutions and nonlinear - in ternary solutions, were obtained. This model for binary and ternary non-electrolyte solutions is discussed. It is shown, that the double-membrane system has rectifying and amplifying properties for osmotic transport and mechanical pressure.

Generalization of the Spiegler-Kedem-Katchalsky frictional model equations of the transmembrane transport for multicomponent non-electrolyte solutions

The Spiegler-Kedem-Katchalsky frictional model equations of the transmembrane transport for systems containing n-component, non-ionic solutions is presented. The frictional interpretation of the phenomenological coefficients of membrane and the expressions connecting the practical coefficients (Lp, sigma i, omega ij) with frictional coefficients (fij) are presented.

Volume osmotic flows of non-homogeneous electrolyte solutions through horizontally mounted membrane

Results of an experimental study of volume osmotic flows in a single-membrane osmotic-diffusive cell, which contains a horizontal, microporous, symmetrical polymer membrane separating water and binary or ternary electrolyte solutions are presented. In the experimental set-up, water was placed on one side of the membrane. The opposite side of the membrane was exposed to binary or ternary solutions. As binary solutions, aqueous potassium chloride or ammonia solutions were used, whereas potassium chloride in 0.25 mol x l(-1) aqueous ammonia solution or ammonia in 0.1 mol x l(-1) aqueous potassium chloride solution were used as ternary solutions. Two (A and B) configurations of a single-membrane osmotic-diffusive cell in a gravitational field were studied. In configuration A, water was placed in a compartment above the membrane and the solution below the membrane. In configuration B the position of water and solution was reversed. Furthermore, the effect of amplification of volume osmotic flows of electrolyte solutions in the single-membrane osmotic-diffusive electrochemical cell was demonstrated. The thermodynamic models of the flux graviosmotic and amplification effects were developed, and the volume flux graviosmotic effect for configurations A and B of a single-membrane osmotic-diffusive cell was calculated. The results were interpreted within the conventional instability category, increasing the diffusion permeability coefficient value for the system: concentration boundary layer/membrane/concentration boundary layer.

[Calculation of the concentration Rayleigh number for isothermal transport processes across a polymeric membrane by a method for measuring diffusion flux in three component non-electrolytic solutions]

A method of determination critical value of concentration Rayleigh Number ((Rci)lim.) in isothermal membrane transport processes of three component non-electrolyte solutions was worked out. The method based on the derived in the paper equation, which include membrane transport coefficients (hydraulic permeability, reflection and diffusive permeability coefficients), solution parameters (viscosity coefficient, density and diffusion coefficient in solution). In order to experimental verification of these method the transport coefficients of symmetric flat polymeric membrane, parameters of solutions and diffusive flux for glucose solution in 0.2 mole/l aqueous ethanol solution were determined. Experiments were carried out by osmotic-diffusive single-membrane double-cell system. One cell in all experiments was filled with pure water while the other with the examined solutions. The experimental critical value of concentration Rayleigh Number (RCi)lim. = 1799 is comparable with theoretical critical value of thermal Rayleigh Number (TT)lim. = 1707.

[A pressure gravity-diffusive effect for flat polymeric membrane and ternary non-electrolyte solutions]

In this paper the pressure gravidiffusive model equation in a single-membrane osmotic-diffusive cell is elaborated. In this cell the flat, microporous and symmetric polymeric membrane so-called Nephrophane positioned horizontally separated water and binary (aqueous glucose or aqueous ethanol) or ternary (glucose in 0.2 mol.l-1 aqueous ethanol or ethanol in 0.05 mol.l-1 aqueous glucose) non-electrolyte solutions. The calculations of pressure gravidiffusive effects for the configurations A and B of the single-membrane osmotic-diffusive cell were elaborated. In configuration A solution was placed in compartment below membrane and in configuration B--above membrane. The calculated result are interpreted in terms of the convective instability that increases the diffusive permeability coefficient of complex: concentration boundary layer/membrane/concentration boundary layer.

Gravitational effects in the passive osmotic flows across polymeric membrane of electrolytic solutions

Results of experimental study of volume flux in one-membrane system were presented. This system contains horizontal, microporous and symmetrical flat polymeric membrane (Nephrophan), which separate water and electrolyte solution. As binary solutions, aqueous ammonia solutions, which density is lower than water density, were used. As ternary solutions the ammonia with KC1 (0.1 or 0.2 mole.l-1) in aqueous solution were used. The density of ternary solutions was lower, higher or the same as water density. Two configurations of membrane system (A and B) in gravitational field were studied. In configuration A, water was in compartment over the membrane and the solution was under the membrane. In configuration B the succession was reverse. The thermodynamic model of flux graviosmotic effect was elaborated, and the calculations of this effect were performed for A and B configurations of one membrane system. The experimental results are interpreted in terms of gravitational instability that reduces concentration boundary layer dimensions and increases the diffusion permeability coefficient value of the complex: boundary layer/membrane/boundary layer.

[Streaming gravity-diffusive effect for a series of two flat polymeric membranes oriented horizontally]

In this paper the results of study flux gravidiffusive effect for a double-membrane osmotic-diffusive cell, in which series of two (Ml and M(r)), microporous and symmetrical flat polymeric membranes (Nephrophane and Cellulose IMP-1). These membranes separate three compartments (l, m, r) containing the heterogeneous and binary (aqueous glucose or ethanol solutions) or ternary (glucose solutions in 0.75 mole.l-1 aqueous ethanol solution or ethanol solutions in 0.1 mole.l-1 aqueous glucose solution) non-ionic solutions. The solution concentrations fulfil the condition Ckl > Ckm > Ckr. The inter-membrane compartment (m) consists of the infinitesimal layer of solution. The volume of compartment m and external compartment (l and r) fulfill the conditions Vm-->0 and Vl = Vr-->infinity respectively. The study of flux gravidiffusive effect for configurations A and B of the double-membrane osmotic-diffusive cell were elaborated. In configuration A solution was placed in compartment below membrane M(r) and water above membrane Ml. In configuration B solution was placed in compartment above membrane Ml and water below membrane Ml. These results are interpreted in terms of the convective instability that increases the diffusive permeability coefficients of complexes: concentration boundary layers/membrane Ml or M(r)/concentration boundary layer.

[Streaming gravity-osmotic effect for a series of two flat polymeric membranes oriented horizontally and ternary non-ionic solutions]

In this paper the results of study flux graviosmotic effect for a double-membrane system, in which two (Ml and M(r)), microporous and symmetrical flat polymeric membranes (Nephrophane and Cellulose IMP-1) separate three compartments (l, m, r) containing the heterogeneous and binary (aqueous glucose or ethanol solutions) or ternary (glucose solutions in 0.75 mole.l-1 aqueous ethanol solution or ethanol solutions in 0.1 mol.l-1 aqueous glucose solution) non-ionic solutions. In this system the solution concentrations fulfill the condition Ckl > Ckm > Ckr. The inter-membrane compartment (m) consists of the infinitesimal layer of solution. The volume of compartment m and external compartment (l and r) fulfill the conditions Vm-->0 and Vl = Vr-->infinity respectively. The calculations of flux graviosmotic effect for configurations A and B of the double-membrane osmotic-diffusive cell were elaborated. In configuration A solution was placed in compartment below membrane M(r) and water above membrane Ml. In configuration B solution was placed in compartment above membrane Ml and water below membrane Ml. These calculated results are interpreted in terms of the convective instability that increases the diffusive permeability coefficients of complexes: concentration boundary layers/membrane Ml or M(r)/concentration boundary layer.

[Gravitational osmotic pressure effect for a series of flat polymer membranes positioned horizontally]

In this paper the results of study pressure graviosmotic effect for a double-membrane osmotic-diffusive cell, in which series of two (Ml and M(r)), microporous and symmetrical flat polymeric membranes (Nephrophane and Cellulose IMP-1) separate three compartments (l, m, r) containing the heterogeneous and binary (aqueous glucose or ethanol solutions) or ternary (glucose solutions in 0.75 mole.l-1 aqueous ethanol solution or ethanol solutions in 0.1 mole.l-1 aqueous glucose solution) non-ionic solutions. In this system the solution concentrations fulfill the condition Ckl > Ckm > Ckr. The inter-membrane compartment (m) consists of the infinitesimal layer of solution. The volume of compartment m and external compartment (l and r) fulfill the conditions Vm-->0 and Vl = Vr-->infinity respectively. The calculations of pressure graviosmotic effect for configurations A and B of the double-membrane osmotic-diffusive cell were elaborated. In configuration A solution was placed in compartment below membrane M(r) and water above membrane Ml. In configuration B solution was placed in compartment above membrane Ml and water below membrane Ml. These calculated results are interpreted in terms of the convective instability that increases the diffusive permeability coefficients of complexes: concentration boundary layers (membrane Ml or M(r)) concentration boundary layer.

[Testing the osmotic-diffusion properties for the membranous dressing Bioprocess]

In order to determine of the osmotic-diffusive properties of membranous dressing Bioprocess, which is a microfibrous network of homogeneous cellulose produced in biosynthesis by Acetobacter, the hydraulic permeability (Lp), reflection (sigma) and diffusive permeability (omega) coefficients were measured. The values of these coefficients showed that this membrane possess a low selectivity. This amount it easy permeable for solvent (water) as well as for solutions (aqueous solutions of glucose, sucrose, ethanol, NaCl or KCl). Thus, it attend a demands make for polymeric materials used in therapy of scald and ulceration.

[Gravity-osmotic pressure effect for flat polymeric membranes and three-component non-electrolyte solutions]

In this paper the classification of the gravitational effects in a passive transmembrane transport is presented. Among these effects there are the flux (flux graviosmotic effect, flux gravidiffusive, current gravielectric effect) and force (pressure graviosmotic effect, pressure gravidiffusive effect, voltage gravielectric effect) gravitational effects. The pressure graviosmotic effect model equation in a single-membrane system is elaborated. In this system the flat, microporous and symmetric polymeric membrane (Nephrophan) positioned horizontally separated water and binary (aqueous glucose) or ternary (glucose-0.2 mole/l) aqueous ethanol) non-electrolyte solutions. The calculations of pressure graviosmotic effects for two (A and B) configurations of the single-membrane system were elaborated. In configuration A solution was placed in compartment below membrane and in configuration B--above membrane. These calculated results are interpreted in terms of the convective instability that increases the diffusive permeability coefficient of complex: boundary layer/membrane/boundary layer.