Osmotic Pressure Values Research Articles

Correlation Analysis of Blood Pressure Variability, Crystalloid Osmotic Pressure, and Cardiovascular Events in Maintenance Hemodialysis Patients.

This study aimed to analyze the correlation between blood pressure variability (BPV), crystalloid osmotic pressure, and cardiovascular events (CEs) in patients undergoing maintenance hemodialysis (MHD). This retrospective analysis was conducted on 71 patients with end-stage kidney disease who underwent hemodialysis at Beilun District People's Hospital from September 2021 to September 2022. The patients were divided into two groups based on the occurrence of CEs: a cardiovascular event group and a non-cardiovascular event group. The 71 patients were divided into two groups based on the occurrence of CEs: the CEs group (25 patients who experienced CEs) and the non-CEs group (46 patients who did not experience CEs). The CEs group had significantly higher levels of crystalloid osmotic pressure, standard deviation of systolic BP (SBP-SD), coefficient of variation of SBP (SBP-CV), SD of diastolic BP (DBP-SD), and DBP-CV (P < .05). Multivariate logistic regression analysis identified crystalloid osmotic pressure, SBP-CV, and DBP-CV as independent risk factors for CEs. The ROC curve analysis indicated that the combined predictive value of crystalloid osmotic pressure, SBP-CV, and DBP-CV was significant, with an area under the curve (AUC) of 0.963. Elevated crystalloid osmotic pressure, SBP-CV, and DBP-CV are critical risk factors with strong predictive value for predicting CEs in MHD patients.

Rheological properties of pharmaceutical substrates produced with Celugel.

Hydrogels, containing a large amount of water and exhibiting high biocompatibility, can improve the rheological properties of formulations and adhere well to the application site. In Poland, only 1 hydrogel substrate is currently approved for pharmaceutical compounding: Celugel, based on hydroxyethyl cellulose (HEC). The aim of this study was to investigate how the variation in the raw material composition of Celugel-based hydrogels affects their osmotic pressure values and selected rheological properties. Ten gel formulations were prepared using a commercial Celugel as the base, with varying percentages of added water, alongside a consistent 5 wt% addition of sucrose. The research methods employed include osmotic pressure, dynamic viscosity, pH measurement, and surface tension using the du Noüy ring tensiometer. The composition of the formulation has a significant impact on the osmotic pressure. Nearly all of the hydrogels exhibited hyperosmotic characteristics relative to living tissues, with measured osmotic pressure values ranging from 160 mOsm/kg H2O to 1,480 mOsm/kg H2O. As anticipated, the viscosity of the formulations increased proportionally with the growing concentration of Celugel ranging from 2.19 mPa·s to 562.87 mPa·s. The composition of Celugel significantly influences its rheological properties and osmotic pressure values, with the concentration of the gelling agent being the most impactful factor. The results suggest that Celugel is suitable for use in formulations intended for nasal administration.

STUDIES ON THE PHYSIOLOGICAL CHARACTERISTICS OF THE HALOPHYTIC SPECIES CRAMBE MARITIMA L. AND THE POSSIBILITY OF ITS INTRODUCTION INTO CULTURE IN THE SOUTHERN AREA OF ROMANIA’S OLTENIA REGION

Crambe maritima L. is a perennial plant from the Brasicaceae family that grows spontaneously in Romania on the beaches of the Black Sea. Its tolerance to salt also makes it tolerant to soil drought. Therefore, it was considered that the sandy and dry soil in the southern part of the Oltenia region could be favorable for the cultivation of this plant, known in the world for its food value. Studies show that the plant develops high values ​​of osmotic pressure and suction force on dry and salty soil and thus manages to absorb optimal amounts of water. Wax impregnation of the leaves reduces water losses and is thus another adaptive advantage. In conditions of moderate salinity or drought, the photosynthesis values ​​are maintained at fairly high values ​​and the net assimilation intensity also has values ​​that ensure a moderate productivity.

Safety Assessment of Channel Seepage by Using Monitoring Data and Detection Information

Seepage analysis has always been the focus of channel safety and stability research. Establishing a diagnosis method based on osmotic pressure monitoring data and combining the detection information to achieve osmotic safety is also an effective way to ensure the safety and stability of osmotic engineering. In this paper, a high-fill channel section of a water diversion project is taken as an example, and the study of osmotic safety is carried out by analyzing the engineering characteristics of linear engineering. High-fill channel sections were selected to study the temporal and spatial characteristics of various monitoring data reflecting the osmotic behavior of linear engineering; that is, these data reflect the time-varying regularity characteristics of the osmotic pressure value and the changing regularity of environmental variables. A single-point multifactor model of the monitoring data was established by establishing an evaluation index system, combining the monitoring index value method and the cloud model theory method according to the distribution law of the measured data and considering the uncertainty of the osmotic pressure data. Additionally, this model was integrated with the set pair analysis method to determine the monitoring data evaluation level; channel detection data information was collected, the abnormal detection of detection information was realized, and the monitoring data results were used to verify the detection results. In this way, an adaptive evaluation method reflecting the working behavior of high-filled channel sections is established, and a diagnostic technology for the safe operation of high-filled channel sections of linear engineering is proposed. The application results show that this method is suitable for engineering an osmotic safety assessment.

Admission electrolyte and osmotic pressure levels are associated with the incidence of contrast-associated acute kidney injury

This retrospective study aimed to explore the relationships between electrolytes and osmotic pressure homeostasis with contrast-associated acute kidney injury (CA-AKI) risk in patients with percutaneous coronary intervention or coronary angiography. We totally enrolled 4386 hospitalized patients, who were categorized into five groups based on the predetermined cutoff values of electrolytes and osmotic pressure. CA-AKI was defined as an increase in serum creatine by 0.5 mg/dL (44.2 mol/L) or a 25% increase of the highest level post-operation compared to baseline. Multivariable logistic analysis was used to examine the association of CA-AKI incidence with electrolytes and osmotic pressure levels. Piecewise linear regression models and restricted cubic spline analysis were further utilized to determine the nonlinear relationship. The results showed U-shaped relationships between sodium, chloride, magnesium, and osmotic pressure levels and CA-AKI incidence. The lowest incidence was observed in the categories of 139–141.9 mmol/L, 107.0–109.9 mmol/L, 0.91–1.07 mmol/L, and 290.0–299.9 mOsm/kg, respectively. J-shaped associations were observed for potassium and phosphate levels and CA-AKI incidence, with the lowest incidence in the categories of 3.50–4.09 mmol/L and 0.96–1.28 mmol/L, respectively. A negative correlation was observed between calcium level and CA-AKI incidence, with the lowest CA-AKI risk in the category of ≥ 2.58 mmol/L. In conclusion, abnormally higher or lower sodium, chloride, magnesium, phosphate, and osmotic pressure levels on admission were associated with increased risks of CA-AKI. While for potassium and calcium, the status of hyperkalemia and hypocalcemia on admission showed more susceptibility for CA-AKI.

The Impact of Minerals on Wheat Plants Grown under Salinity Stress

The present work has been conducted to study the impact of Zn (20 and 200 μM) or Ni (1 and 100 μM) on growth, metabolic activities, osmotic pressure and heavy metal of wheat cultivar (cv. Gimiza 11) under salt stress conditions. Harvest index was significantly decreased by 75% at -0.3 MPa and -1.2 MPa decreased by 53%. Length of root, stem and spike, and leaf area were slightly reduced up to -0.9 MPa NaCl level, after that a significant reduction was recorded. Total sugar was increased in the shoot and spike, while decreased in the root with increasing salinity levels. On the other side, total protein was increased in the shoot while decreased in both the root and spike. Osmotic pressure was increased as increasing salinity levels. Treatment of wheat plants with Zn or Ni alleviated generally salt injury in the harvest index, length of root, shoot and spike and leaf area. This effect was more obvious with Zn treatments. Mineralization treatments increased total sugar in the three tested organs while did not change the total protein. Zn content was increased at -1.2 MPa level while Ni was decreased. Treatments with Zn or Ni mostly increased Zn while causing a reduction in the Ni content. These treatments also increased the values of osmotic pressure compared with the equivalent levels of control plants.

Development and Validation of a Nomogram Incorporating Colloid Osmotic Pressure for Predicting Mortality in Critically Ill Neurological Patients.

Backgrounds: The plasma colloid osmotic pressure (COP) values for predicting mortality are not well-estimated. A user-friendly nomogram could predict mortality by incorporating clinical factors and scoring systems to facilitate physicians modify decision-making when caring for patients with serious neurological conditions.Methods: Patients were prospectively recruited from March 2017 to September 2018 from a tertiary hospital to establish the development cohort for the internal test of the nomogram, while patients recruited from October 2018 to June 2019 from another tertiary hospital prospectively constituted the validation cohort for the external validation of the nomogram. A multivariate logistic regression analysis was performed in the development cohort using a backward stepwise method to determine the best-fit model for the nomogram. The nomogram was subsequently validated in an independent external validation cohort for discrimination and calibration. A decision-curve analysis was also performed to evaluate the net benefit of the insertion decision using the nomogram.Results: A total of 280 patients were enrolled in the development cohort, of whom 42 (15.0%) died, whereas 237 patients were enrolled in the validation cohort, of which 43 (18.1%) died. COP, neurological pathogenesis and Acute Physiology and Chronic Health Evaluation II (APACHE II) score were predictors in the prediction nomogram. The derived cohort demonstrated good discriminative ability, and the area under the receiver operating characteristic curve (AUC) was 0.895 [95% confidence interval (CI), 0.840–0.951], showing good correction ability. The application of this nomogram to the validation cohort also provided good discrimination, with an AUC of 0.934 (95% CI, 0.892–0.976) and good calibration. The decision-curve analysis of this nomogram showed a better net benefit.Conclusions : A prediction nomogram incorporating COP, neurological pathogenesis and APACHE II score could be convenient in predicting mortality for critically ill neurological patients.

A method of determining osmotic pressure for low-clay shale with different salt ions considering effect of dynamic permeability on flow

Fluid penetration from water-based drilling fluids into shale formations results in swelling and subsequent borehole instability. Generally, inorganic or organic salts are used to generate necessary chemical osmotic pressure to inhibit shale hydration and swelling. However, the relationship between salt ions and shale osmotic pressure is not clear. In this study, a dynamic model is proposed to determine osmotic pressure of Longmaxi shale, Southwest China. In addition, the model considers the pressure changes under actual working conditions and the influence of the solution seepage process in shale pores. The osmotic pressure and discipline of Longmaxi shale with NaCl, KCl, CaCl2 and HCOONa were analyzed. Results indicate that the osmotic pressure of KCl and HCOONa decreases with increasing salinity, and the osmotic pressure of NaCl first decreases and then increases with increasing salinity. Calculated results and experimental results have been compared in the study, and the reliability of the model for Longmaxi shale has been proved. The Longmaxi shale has the lowest osmotic pressure value at a salinity of about 0.25 for NaCl solution. Moreover, experimental and theoretical calculation results indicate that the osmotic pressure in Longmaxi shale is lower than 0.2 MPa and is not enough to have a decisive effect on borehole stability. However, the KCl solution with a high concentration can reduce the osmotic pressure by 1.8 MPa as CEC is 0.3 meq/g. The established model with different salt ions can provide theoretical and technical support for low-clay shale gas development.

Ultrasonic detection of cavitation in a membrane under osmotic pressure

Cavitation in a membrane has been proposed as the principal cause of the low flux in osmotically driven membrane processes (ODMPs). In this study, an ultrasonic signal combined with a fast Fourier transform (FFT) analysis was adopted to detect cavitation in the membrane of ODMPs. The ultrasonic amplitude decreased rapidly under an osmotic pressure of 88.59 bar at the initial phase, indicating that the cavitation mainly occurred at the beginning of the filtration. In addition, cavitation was significantly affected by osmotic pressure, which indicated a higher cavitation probability with larger osmotic pressure values. Cavitation, which significantly reduces the membrane flux in ODMPs, can be delayed by applying hydraulic pressure on a feed solution. The flux rose to 16.50 L·m−2 h−1 from 10.61 L·m−2 h−1 with a hydraulic pressure increase to 2 bar from 0 bar under an osmotic pressure of 88.59 bar. However, the membrane flux could not be improved indefinitely owing to concentration polarization.

The Need for Accurate Osmotic Pressure and Mass Transfer Resistances in Modeling Osmotically Driven Membrane Processes.

The widely used van ’t Hoff linear relation for predicting the osmotic pressure of NaCl solutions may result in errors in the evaluation of key system parameters, which depend on osmotic pressure, in pressure-retarded osmosis and forward osmosis. In this paper, the linear van ’t Hoff approach is compared to the solutions using OLI Stream Analyzer, which gives the real osmotic pressure values. Various dilutions of NaCl solutions, including the lower solute concentrations typical of river water, are considered. Our results indicate that the disparity in the predicted osmotic pressure of the two considered methods can reach 30%, depending on the solute concentration, while that in the predicted power density can exceed over 50%. New experimental results are obtained for NanoH2O and Porifera membranes, and theoretical equations are also developed. Results show that discrepancies arise when using the van ’t Hoff equation, compared to the OLI method. At higher NaCl concentrations (C > 1.5 M), the deviation between the linear approach and the real values increases gradually, likely indicative of a larger error in van ’t Hoff predictions. The difference in structural parameter values predicted by the two evaluation methods is also significant; it can exceed the typical 50–70% range, depending on the operating conditions. We find that the external mass transfer coefficients should be considered in the evaluation of the structural parameter in order to avoid overestimating its value. Consequently, measured water flux and predicted structural parameter values from our own and literature measurements are recalculated with the OLI software to account for external mass transfer coefficients.

Label-Free Resistance Cytometry at the Orifice of a Nanopipette

Development of new principles and techniques at the single-cell level is significantly important since cells as basic units of living organisms always bear large heterogeneity. Herein, we demonstrate a new electrochemical principle for single-cell analysis based on an ion current blockage at the orifice of a nanopipette, defined as resistance cytometry. The amplitude and the frequency of ion current transients show strong dependence on the size and the concentration of cells, which could be used for in situ cell sizing and counting. This technique shows good ability to detect the size change of RBCs under stimulations of different pH and osmotic pressure values. More importantly, the as-presented resistance cytometry can distinguish lymphoma blood cells from normal blood cells for patient blood samples. The as-presented resistance cytometry is label-free, non-invasive, and non-destructive, which not only opens new opportunities for single-cell analysis but also provides a new platform for cell-related medical diagnostic technologies.

Эволюция структуры и зернограничного ансамбля никеля при диффузионном отжиге в условиях сегрегирующей примеси (серебра) по границам зерен

Investigations of the effect of an impurity (silver) segregating along the grain boundaries of nickel on the evolution of the structure and grain-boundary ensemble under conditions of diffusion annealing at a temperature of 823 K for 6 hours have been carried out. It is shown that, under these conditions, the development of a diffusion-induced recrystallization (DIR) process is observed in the Ni(Ag) system, in contrast to the Ni(Cu) system, in which the process of diffusion-induced grain boundary migration (DIGM) was observed. The estimates made have shown that a possible reason for the fact that diffusion-induced migration of grain boundaries practically does not occur in the Ni(Ag) system can be significantly lower than in the Ni(Cu) system the value of osmotic pressure as the driving force for the DIGM process.

P1158DOES THE PERITONEUM SWELLS OR SHRINK DURING PERITONEAL DIALYSIS?

Abstract Background and Aims The width of the peritoneum (composed mainly of connective tissue and relatively free of vasculature) is increased in patients on peritoneal dialysis compared to healthy subjects. We investigated to what extent increased intraperitoneal (ip) hydrostatic and osmotic pressures following the infusion of dialysis fluid will change hydration status and width of the peritoneum. Method Using linear theory of poroelasticty, clinical data on transport parameters and experimental data on elastic characteristics of the interstitium, the relative change of the width of the poroelastic layer subject to the combined effect of external hydrostatic and effective osmotic pressures (that is, ideal osmotic pressure multiplied by reflection coefficient for osmotic agent) can be described as a function of effective pressure and elastic modulus of the layer: Lmod/L0 = 1/(1-deltaP*/lambda*), where L0 is initial thickness of the tissue, Lmod is modified thickness of the layer, deltaP* is change in effective combined pressure, and lambda* is the elastic modulus of the poroelastic material. The same formula describes also the change in fractional free fluid volume ratio, thetaF. The elastic modulus of the connective tissue was assumed to be 110 mmHg, as measured for the subcutaneous layer of the tip of mouse tail by Swartz et al (J Biomech, 1999), and reflection coefficient for glucose in the interstitium of 0.0035 as estimated by Stachowska-Pietka et al (NDT, 2019) from clinical data for patients on peritoneal dialysis. Results The ip hydrostatic pressure increases by 2-3 mmHg to 15 mmHg at rest depending on infused volume of dialysis fluid (and posture, body weight and location in abdominal cavity), and may increase to 100 mmHg during activities as coughing, whereas the osmotic pressure of glucose 3.86% dialysis fluid is around 400 mmHg above the osmotic pressure of plasma and interstitial fluid (in equilibrium with plasma). However, due to the low reflection coefficient of interstitium, the effective osmotic pressure of dialysis fluid minus the physiological value of interstitial osmotic pressure is only 1.4 mmHg, and is quickly decreasing with dwell time. Therefore, hydrostatic pressure is the dominant factor for interstitial hydration. Assuming ip pressure of 15 mmHg, the stretch of the peritoneum increases its equilibrium width (at 0 mmHg and isotonic interstitial fluid) by 15%. During physical activities peritoneum may transiently thicken even more. Conclusion The peritoneum becomes overhydrated after infusion of dialysis fluid, which increases interstitial hydrostatic pressure; the thickness and fractional free fluid volume of the peritoneum increase by 15% although transiently higher increases may occur following activities that increase intraperitoneal pressure. The mechanical changes in the peritoneum may contribute to the biological changes in cells present there, as fibroblasts and mesothelial cells. The swelling of the peritoneum is in agreement with the increase in the fractional free fluid volume of the intramuscular interstitium behind the peritoneum as reported by Zakaria et al (Am J Physiol Heart Circ Physiol, 1999).

Osmotic pressure and transport coefficient in ultrafiltration: A Monte Carlo study using quantum surface charges

The calculation of the Osmotic Pressure and the Diffusion Coefficient, characterizing the cake layer developing during the Ultrafiltration (UF) of Bovine Serum Albumin (BSA), through a Multiscale Model based on Quantum Mechanics (QM) and Monte Carlo methods (MC) was the aim of this work. From the ab-initio results described in previous works, the distribution of the BSA surface charges was used. A home-made Metropolis MC algorithm, aimed at simulating the formation of BSA loose or concentrated layers during membrane operations, was also implemented. In such a MC algorithm, a DLVO energy calculation methodology of the adsorbed system was developed. Different MC simulations and Hypernetted Chain theory (HNC) calculations were performed so to determine both the Osmotic Pressure and the Diffusion Coefficient of BSA according to the Chun and Bowen approach, thus allowing a comparison between the calculated values of osmotic pressure and a set of experimental data taken from the literature. Such a comparison showed a good agreement between the simulated and the experimental results.

Chang approximation for the osmotic pressure of dilute to concentrated solutions

As many regions around the world are facing water scarcity, reverse osmosis (RO) has attracted attention to supply fresh water to such areas. To design and develop energy-efficient RO processes, accurate osmotic pressure values of salt water are critical, yet conventional models of osmotic pressure have significant deviations from the actual values. In addition, absence or high charge of authentic osmotic pressure databases prevents accessing authentic data. Here, we propose combining the Chang correction factor, a polynomial in solution concentration, with traditional osmotic pressure models to approximate the osmotic pressure of dilute to concentrated solutions with high accuracy. The Chang correction factor is determined by regressing a handful of authentic osmotic pressure data divided by theo- retical values calculated using traditional models. Multiplication of resulting polynomials back to corresponding tradi- tional models enables accurate approximation of the authentic osmotic pressure of dilute to concentrated solutions with R2 approaching 1. In addition, generality of the strategy over aqueous and organic solutions is demonstrated by approx- imating osmotic pressure of NaCl and sucrose aqueous solutions and C2H4Cl2-C6H6 and C3H6Br2-C2H4Br2 organic solutions. The approximation strategy proposed and assessed here will be useful to simulate and develop processes for seawater desalination and various industries with high importance.

Abstract 2005: Optimized range of osmotic pressure and viscosity for a lymphatic drug delivery system

Abstract The lymphatic drug delivery system (LDDS) is a method that allows the injection of drugs into sentinel lymph nodes (SLNs) to facilitate their delivery to downstream lymph nodes (LNs) via the lymphatic network to treat or prevent cancer cell development in both LNs. A high concentration of drug is effectively maintained in both LNs. Here we show that therapeutic effects in metastatic LNs depend on the osmotic pressure and viscosity of the administered drug in a metastatic mouse (MXH10/Mo-lpr/lpr) model. We found using an in vivo bioluminescence imaging system that indocyanine (ICG) solutions were retained in the proper axillary lymph node (PALN) at an osmotic pressure &amp;gt; 1,700 kPa and 6 mPa·s viscosity, when ICG solution was injected into the SiLN to deliver it to the (PALN). Edematous swelling was detected near the SiLN at &amp;gt; 3,500 kPa osmotic pressure and 400 mPa·s viscosity. Furthermore, we established that the therapeutic effects of drugs on metastatic PALN were observed in the osmotic pressure range 1000 - 2400 kPa and viscosity range 2 - 30 mPa·s, after tumor cells were injected into the SiLN to induce metastasis in the PALN. Cisplatin solution was injected into the accessory axillary lymph node to deliver cisplatin to the metastatic PALN. Our results demonstrate the optimized values of osmotic pressure and viscosity for LDDS. We anticipate our results to be a starting point for more sophisticated drug administration by a LDDS. Citation Format: Tetsuya Kodama, Shiro Mori. Optimized range of osmotic pressure and viscosity for a lymphatic drug delivery system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2005.

Измерение осмотического давления почвенного раствора криоскопическим методом и его метрологическая характеристика

Cryoscopic technique to measure soil solution osmotic pressure is based on the thermodynamic relationship between chemical potential (pressure) and decresasing of the soil solution freezing temperature. The pressure is determined on the basis of the freezing temperature difference beyween distilled water and soil solution. To characterize metrologically soil solution osmotic pressure (OP) measurements by cryoscopic method a laboratory experiment was carried out with several different soil samples, collected from the A horizon of the typicalheavy-clay chernozm (Kursk region, Russia, and light-cloured clay and sandy chestnut soils (Volgograd region, Russia). Sodium chloride solution was added to soil aliquots at 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 eq/L, while Na2SO4 solution was added at 0.50 0.85 eq/L. Distilled water was added to the control variants. Depending on the granulometric composition of soils, soil water content was adjusted to 28, 23 and15%. The samples prepared in such a way were placed in 40-ml Dewar vacuum flasks with 10-4-10-5 mm Hg of vaccuum. The cryoscope measured temperature according to the Beckman thermometer scale. The temperature of the cooling mixture of crushed ice and NaCl (1:5 v/v) in Dewar flasks was maintained in the range of -21º -17º C. The freezing of soil solutions and distilled water went with overcooling. The temperature jump was indicated by clear Hg meniscus stop at the beginning of crystallization. Statistical analysis of the data obtained produced correlations and corresponding scales of the relative standard deviation(V, %) and relative permissible deviation(Drel, %) of the measured OP values. The V was shown to range from 2 to 50%, while the Drel varied from 5 to 100% between 1 and 15 atm. The threshold between the quantitative and semiquantitative esimates when V=30% was found to lie between 1.3-1.7 atm. Based on the correlation between Drel values and the measured OP, a scale for estimating OP is suggested: when Drel is 100% the corresponding OP value is 0.9-1.2 atm, at 80% Drel 1.2-1.7, at 60% Drel 1.7-2.2, at 40% Drel 2.2-3.2, at 30% Drel 3.2-4.2, at 20% Drel 4.2-9.2, at 10% Drel 9.2-10.2 atm, whereas at 9% Drel the OP can be estimated as ranging 10.2-11.2 atm, while at 8% Drel as 11.2-12.5, at 7% Drel as 12.5-14.2 and at 5% Drel as 14.2-14.5 atm. The scale can be used to estimate the reproducibility of experimental measures of soil solution osmotic pressure.

Dependence of the Osmotic Pressure and Electrical Conductivity of Soil Solutions on the Soil Water Content

The osmotic pressure and electrical conductivity were determined with the use of instrumental methods (centrifuging, conductometry, and cryoscopy) in equilibrium soil solutions as the functions of moisture (the mass ratio between solid and liquid phases) for the soils of different geneses and textures. These functions proved to have a nonlinear character with one extremum. A theoretical substantiation to this phenomenon is suggested. It is based on the concept of competing interphase interactions in soil and develops the classical ideas by A.A. Rode. Upon the low soil water content, surface (molecular and ion-electrostatic) forces of the solid phase bind water molecules and prevent them from hydrating ions and dissolving electrolyte salts in the soil solution; as a result, electrical conductivity and osmotic pressure values approach zero in this case. With an increase in the water content, water molecules escape gradually from the energy field of surface forces, and their activity (chemical potential) and dissolving capacity also increase. This results in the expected growth of the electrical conductivity and osmotic pressure of the equilibrium solution extracted from the soil. The maximum values of the studied parameters are observed at the water content approximately equal to the maximum molecular water capacity (or to the boundary zone, within which capillary gravitational forces influencing the soil liquid phase become prevailing over the surface interphase interaction forces). The further increase in the soil water content lowers the electrical conductivity and osmotic pressure of equilibrium solution because of dilution of the fixed mass of electrolyte salts. For quantitative description of the revealed functional dependence, we suggest an empirical mathematical model in the form of modified equation of lognormal distribution.

Refined Alkali Metal Ion Parameters for the OPC Water Model

Using all‐atom molecular dynamics simulations with Joung–Cheatham ion parameters and the OPC water model, the osmotic pressure values of monovalent alkali metal chloride solutions (KCl and NaCl) were calculated and compared to experimental values. The simulated osmotic pressure data were overestimated at high concentrations. To close the gap between simulation and experiment, we attempted to modify the Lennard–Jones interaction parameters of the cation–water oxygen pairs explicitly using the unequal Lorentz–Berthelot combination rule, such that experimental osmotic pressure values for a range of concentrations were well reproduced. These novel ion parameters could be potentially beneficial to simulation studies of G‐quadruplex DNA molecules, where ions play a key role in their folding process.

Colloid osmotic pressure during and after surgical interventions in adult and geriatric dogs

ABSTRACT: The objective this study is to evaluate colloid osmotic pressure (COP) fluctuations in adult and senile dogs during surgical interventions. Thirty-six healthy dogs to surgical interventions, distributed in two groups, A and B, according to their age, and were all subjected to the same anesthetic protocol. Values of albumin, total plasmatic protein and COP were evaluated from samples collected before pre-anesthetic medication, fifteen minutes after pre-anesthetic medication, and shortly after the end of the intervention. Results were tested using t-test to compare among groups and ANOVA for repeated measures followed by Tukey’s test to compare different moments within the same group. Statistical significance was set at p&lt;0.05. In both groups, significant decreases were observed in colloid osmotic pressure, as well as albumin and total proteins (p&lt;0.001). Despite slightly lower COP values for the group of adult animals, this difference was not significant as there was a high individual variation within groups. The results therefore indicate no difference in colloid osmotic pressure values or fluctuation patterns among adult and senile dogs (p=0.124). The observed results indicate that colloid osmotic pressure decreases significantly during surgical procedures, due to hypotension caused by the anesthetic drugs and to hemodilution caused by the fluid administration but there is no difference between groups. However, in both adult and senile dogs, these variables recover gradually after the animals awaken, through increased urine production and recovery of vascular tonus, indicating the successful reestablishment of homeostasis.