Osmotic and activity coefficients of sodium sulphate in water from 50 to 150 °C

1981 ◽  
Vol 59 (1) ◽  
pp. 123-126 ◽  
Author(s):  
Om. N. Bhatnagar ◽  
Alan N. Campbell
Keyword(s):  
Activity Coefficients ◽  
Osmotic Coefficients ◽  
Sodium Sulphate ◽  
Differential Manometer ◽  
Solvent Interactions ◽  
Pitzer’S Equation ◽  
Pitzer's Equation ◽  
Pressure Lowering ◽  
Different Temperatures ◽  
The Mean

The vapour pressure lowering, ΔP, of sodium sulphate solutions in water was measured in the concentration range 0.4 to 1.8 m and the temperature range 50 to 150 °C by the use of a differential manometer. ΔP values were used to calculate the osmotic coefficient of sodium sulphate solutions. Pitzer's equation for osmotic coefficients was used to evaluate βMX(0), βMX(1), and [Formula: see text] at each temperature. An attempt has been made to explain the changes in these constants in terms of the ion–ion and ion–solvent interactions. Using these constants, the mean activity coefficients, γ±, of sodium sulphate were calculated at different temperatures and concentrations using Pitzer's equation.

scholarly journals Measurement and correlation of solubility of ethylparaben in pure and binary solvents and thermodynamic properties of solution

2019 ◽  
Vol 48 (2) ◽  
pp. 332-347 ◽  
Author(s):  
Alba Miledy Romero Nieto ◽  
Nestor E. Cerquera ◽  
Daniel Ricardo Delgado
Keyword(s):  
Mole Fraction ◽  
Activity Coefficients ◽  
Molecular Level ◽  
Bioactive Compound ◽  
Analysis Data ◽  
Binary Solvents ◽  
Solvent Interactions ◽  
Solubility Behavior ◽  
Pure Solvent ◽  
Different Temperatures

Solubility data of bioactive compound such as ethylparaben (EtP) are important for the scientific and community. Therefore, in present study, solubility, solution thermodynamics and solute-solvent interactions (at molecular level) of EtP in nine cosolvent mixtures (1-propanol {n-PrOH) (1) + methanol (MeOH) (2)} including pure solvent (methanol and 1-propanol) at three different temperatures, i.e. (T =283.2 K, 298.2 K, and 313.2 K) and constant pressure (p = 0.1 MPa) were studied. Experimental solubility of EtP (expressed in mole fraction) was observed highest in n-PrOH at 313.2 K, so, mole fraction solubility of EtP (x3) increases when temperature arises and increases with n-PrOH proportion increasing. Ideal solubilities of  EtP were estimated using their thermal parameters at three different temperatures. Ideal solubilities of EtP were observed similar to experimental solubilities of EtP at each temperature. With the help of ideal solubilities of EtP, activity coefficients were estimated. Based on estimated values of activity coefficients, highest interactions at molecular level were observed in rich-MeOH mixtures. Apparent thermodynamic analysis data showed endothermic and enthalpy-driven dissolution of EtP in each solvent and mixture studied. Solubility behavior was adequately correlated by means of the van’t Hoff and Yalkowsky-Roseman models combined.

Early results of micropulse transscleral cyclophotocoagulation for the treatment of glaucoma

2019 ◽  
Vol 30 (4) ◽  
pp. 700-705 ◽  
Author(s):  
Alexander T Nguyen ◽  
Jessica Maslin ◽  
Robert J Noecker
Keyword(s):  
Intraocular Pressure ◽  
Continuous Wave ◽  
Open Angle Glaucoma ◽  
Case Series ◽  
Angle Closure ◽  
Secondary Outcome ◽  
Early Results ◽  
Pressure Lowering ◽  
Transscleral Cyclophotocoagulation ◽  
The Mean

Purpose: To describe our clinical experience with the efficacy and safety of micropulse transscleral cyclophotocoagulation as a treatment for glaucoma. Methods: In this retrospective case series, we reviewed the charts of 95 consecutive patients with various glaucoma subtypes who underwent micropulse transscleral cyclophotocoagulation. Patients were offered micropulse transscleral cyclophotocoagulation if they had perimetric glaucoma refractory to intraocular pressure–lowering topical medications and who were poor candidates for traditional filtering surgery. Eligible patients were treated with the Micropulse P3 device (IQ 810 Laser Systems; Iridex, Mountain View, CA, USA) at 2.0–2.5 W for a duration of 90 s per hemisphere at a 31.3% duty cycle. If a retreatment was needed, the power was increased to up to 3.0 W with other parameters remaining the same. Patients were considered successfully treated if their intraocular pressure was lowered by at least 20% compared to their baseline. The main outcome measure was post-operative intraocular pressure; secondary outcome measures included the number of adverse events and complications that occurred with treatment. Results: The glaucoma subtypes treated included primary open-angle glaucoma (n = 51), exfoliation glaucoma (n = 24), chronic angle-closure glaucoma (n = 15), and congenital/juvenile glaucoma (n = 5). The mean pre-operative intraocular pressure was 25.1 ± 5.3 mm Hg and the mean post-operative intraocular pressure at 12 months was 17.5 ± 5.1 mm Hg (p = 0.004). The mean number of intraocular pressure–lowering medications used preoperatively was 3.0 ± 1.1; the mean number of medications used at the 12-month post-operative visit was 1.4 ± 1.0 (p = 0.03). Success with one treatment was achieved in 73 (76.8%) of patients. With multiple treatments, all patients had significant intraocular pressure–lowering compared to baseline. The maximum number of treatments received by any single patient was 5. There were no instances of prolonged intraocular inflammation or long-term hypotony. Conclusion: Micropulse transscleral cyclophotocoagulation appears to be a safe and efficacious treatment for glaucoma. Given its improved safety profile compared to continuous-wave transscleral cyclophotocoagulation, it deserves consideration as a primary procedure.

Oxidation Behaviors of TiB2-TiCX and TiB2-TiCX/15SiC Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 179-183 ◽  
Author(s):  
De Gui Zhu ◽  
Hong Liang Sun ◽  
Yu Shu Wang ◽  
Liang Hui Wang
Keyword(s):  
Oxidation Resistance ◽  
Effective Temperature ◽  
Hot Isostatic Pressing ◽  
Ceramic Composites ◽  
Optical Micrograph ◽  
Different Temperatures ◽  
The Mean ◽  
Mean Time ◽  
Oxidation Behaviors

Fully dense samples of TiB2-TiCX and TiB2-TiCX/15SiC ceramic composites were fabricated by in-situ synthesis under hot isostatic pressing from TiH2, B4C and SiC powders. Their oxidized behaviors at different temperatures were tested. Optical micrograph studies and thermo-gravimetric analyses show that the highest effective temperature of oxidation resistance is 700°C for TiB2-TiCX, and 1100°C for TiB2-TiCX/15SiC. The weight gain of TiB2-TiCX/15SiC below 1100°C is quite low, and it rises up suddenly when the temperature reaches 1200°C. Thus, the highest effective temperature of oxidation resistance is 1100°C for TiB2-TiCX/15SiC. The oxidation dynamic curves of TiB2-TiCX/15SiC ceramics accord with the parabola’s law. The activation energy of TiB2-TiCx/15SiC (189.87kJ.mol-1) is higher than that of TiB2-TiCx (96.44kJ.mol-1). In the oxidation process of TiB2-TiCx/15SiC, TiB2 reacts with oxygen and generates TiO2 and B2O3 at first. A layer of whole homogeneous oxide film cannot be formed, in the mean time, the oxidation of TiC begins. When temperature goes up to 1000°C, TiC phase is totally oxidized. SiC is oxidized to SiO2 at about 900°C, Meanwhile, TiO2 forms denser film than B2O3, which grows and covers the surface of the material, and gives better property of oxidation resistance.

scholarly journals Development and health status of Centropomus undecimalisparasitized by Rhabdosynochus rhabdosynochus (Monogenea) under different salinity and temperature conditions

2015 ◽  
Vol 24 (3) ◽  
pp. 350-356 ◽  
Author(s):  
Giovanni Lemos de Mello ◽  
Gabriela Tomas Jerônimo ◽  
Karen Roberta Tancredo ◽  
Jéssica Brol ◽  
Evelyn Jacques de Almeida ◽  
...  
Keyword(s):  
Hematological Parameters ◽  
Hemoglobin Concentration ◽  
Economic Losses ◽  
Mean Corpuscular Hemoglobin ◽  
Experimental Conditions ◽  
Different Temperatures ◽  
The Mean ◽  
Positive Correlations ◽  
C 32 ◽  
Wbc Count

This study evaluated the correlation of hematological parameters with the mean abundance of the monogenean helminth Rhabdosynochus rhabdosynochus in Centropomus undecimalis reared at different temperatures and salinities. The experimental conditions were: 28 °C/0 ppt (parts per thousand); 28 °C/15 ppt; 28 °C/32 ppt; 25 °C/0 ppt; 25 °C/15 ppt; and 25 °C/32 ppt. The prevalence was 100.0% in fish at 28 °C/15 ppt, 28 °C/32 ppt and 25 °C/15 ppt, which was significantly different (p < 0.05) from those at 25 °C/32 ppt. The red blood cell (RBC) count, hematocrit and total leukocyte (WBC) count were significantly higher in fish at 28 °C/15 ppt and 28 °C/32 ppt. The mean abundance of R. rhabdosynochus, hematocrit and RBC showed positive correlations (P < 0.05) with temperature (ρ= 0.3908; ρ= 0.4771 and ρ = 0.2812). Mean abundance showed negative correlations with hemoglobin (ρ= -0.3567) and mean corpuscular hemoglobin concentration (MCHC) (ρ = -0.2684). No correlation between abundance and salinity was detected among the experimental conditions (ρ = -0.0204). The low numbers of monogeneans recorded (min -1 and max -33) explain the few changes to fish health. This suggests that these experimental conditions may be recommended for development of rearing of C. undecimalis in Brazil, without any influence or economic losses from R. rhabdosynochus.

Effect of Sodium Sulphate on the Volumetric, Rheological and Refractometric Properties of some Disaccharides in Aqueous Solutions at Different Temperatures

2008 ◽  
Vol 222 (1) ◽  
pp. 177-204 ◽  
Author(s):  
Parampaul Kaur Banipal ◽  
Harpreet Singh Dhanjun ◽  
Suman Sharma ◽  
Harneet Hundal ◽  
Tarlok Singh Banipal
Keyword(s):  
Aqueous Solutions ◽  
Sodium Sulphate ◽  
Different Temperatures

Molecular Interactions Investigation of L-Histidine in Water and in Aqueous Citric Acid at Different Temperatures Using Volumetric and Acoustic Methods

2018 ◽  
Vol 232 (3) ◽  
pp. 393-408 ◽  
Author(s):  
Dinesh Kumar ◽  
Shashi Kant Sharma
Keyword(s):  
Citric Acid ◽  
Molar Volume ◽  
Atmospheric Pressure ◽  
Apparent Molar Volume ◽  
Adiabatic Compressibility ◽  
Acid Solutions ◽  
Solvent Interactions ◽  
Intermolecular Free Length ◽  
Acoustic Methods ◽  
Different Temperatures

AbstractDensities,ρand ultrasonic speeds, u of L-histidine (0.02–0.12 mol·kg−1) in water and 0.1 mol·kg−1aqueous citric acid solutions were measured over the temperature range (298.15–313.15) K with interval of 5 K at atmospheric pressure. From these experimental data apparent molar volume ΦV, limiting apparent molar volume ΦVOand the slopeSV, partial molar expansibilities ΦEO, Hepler’s constant, adiabatic compressibilityβ, transfer volume ΦV, trO, intermolecular free length (Lf), specific acoustic impedance (Z) and molar compressibility (W) were calculated. The results are interpreted in terms of solute–solute and solute–solvent interactions in these systems. It has also been observed that L-histidine act as structure maker in water and aqueous citric acid.

IV. On the expansion by heat of metals and alloys

1867 ◽  
Vol 15 ◽  
pp. 220-222
Keyword(s):  
Specific Gravity ◽  
Metals And Alloys ◽  
The Body ◽  
The Other ◽  
Different Temperatures ◽  
The Mean

In a paper “ On the Expansion by Heat of Water and Mercury” *, a method of determining the expansion of bodies is described, by which good results can be obtained with comparatively small quantities of the substances to be experimented with. This method, that of weighing the body in water at different temperatures, has been employed for the present research. The results obtained are given in the following Tables:— From the above the following conclusion is drawn-namely, that just as it may be said that the specific gravity of an alloy is approximately equal to the mean specific gravities of the component metals , so also from the foregoing we may deduce that the volume which an alloy will occupy at any temperature between 0° and 100° is approximately equal to the mean of the volumes o f the component metals at the same temperature, or, in the other words, the cubical or linear coefficients o f expansion by heat of an alloy between 0° and 100° are approximately equal to the mean of the cubical or linear coefficients of expansion by heat o f the component metals .

NaCl and CaCl2 activity coefficients in mixed aqueous solutions

1965 ◽  
Vol 20 (6) ◽  
pp. 1332-1336 ◽  
Author(s):  
Edward W. Moore ◽  
James W. Ross
Keyword(s):  
Ionic Strength ◽  
Activity Coefficients ◽  
Technical Assistance ◽  
Osmotic Coefficients ◽  
Electrode System ◽  
Glass Electrode ◽  
Concentration Data ◽  
Harned's Rule ◽  
Potentiometric Measurement

In the investigation of numerous physiological phenomena it is the activity of an ion species which is desired, rather than stoichiometric concentration. The calculation of mean ionic activity from known concentration data requires accurate activity coefficients (ggr). This report concerns the determination of ggrNaCl and ggrCaCl2 in mixed NaCl-CaCl2 solutions by potentiometric measurement with a sodium-selective glass electrode-Ag/AgCl electrode system over the ionic strength range 0.05–0.5 m. Log ggrNaCl varied linearly, at constant total ionic strength, with the ionic strength of CaCl2 in the mixture, in accordance with Harned's rule. From data thus obtained, ggrCaCl2 coefficients in such mixed solutions have been calculated and compared with values calculated from published osmotic data. Resulting activity coefficient curves for ggrCaCl2 are presented over the concentration range encountered in serum and other extracellular fluids. Note: (With the Technical Assistance of Leonard Kaye and Leonard L. Anderson) glass electrodes; ion interaction; electrolyte metabolism; Harned's rule; membrane transport; osmotic coefficients Submitted on March 11, 1965

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