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Mali Ram Gupta - One of the best experts on this subject based on the ideXlab platform.
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application of multivariate methods to evaluate the functionality of bovine and vegetable derived magnesium stearate
Journal of Pharmaceutical Sciences, 2014Co-Authors: Rahul V. Haware, Ramya Shivagari, Paul R. Johnson, Scott Staton, William C. Stagner, Mali Ram GuptaAbstract:ABSTRACT This work distinguishes and quantifies the effects of bovine- and vegetable-derived magnesium stearate (MgSt) molecular and macroscopic properties on lubrication efficiency using multivariate analysis. Principal component analysis (PCA) and partial least-square regression (PLS) were used to evaluate and quantify the lubricant effectiveness on a model tablet formulation. PCA score and loading plots showed a separation of model formulations based on the MgSt sources, which indicated different bovine- and vegetable-derived MgSt lubrication potential. PLS quantified the MgSt molecular [Enthalpy of dehydration (ΔHd), Enthalpy of Melting (ΔHm), percent crystallinity, and moisture content] and macroscopic [particle size ( d 50 ), specific surface area (SSA-MgSt), and MgSt Hausner ratio (HF-MgSt)] properties, their interactions, and square effects on formulation powder flow and tableting properties relating to MgSt's lubrication effectiveness. For crystalline MgSt, moisture content, HF-MgSt, d 50 , and SSA-MgSt showed a major influence on the lubrication efficiency compared with the other MgSt molecular properties (percent crystallinity, ΔHm, and ΔHd). Amorphous MgSt showed poor lubrication, and none of its molecular or macroscopic properties showed significant effects on lubrication efficiency. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
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application of multivariate methods to evaluate the functionality of bovine and vegetable derived magnesium stearate
Journal of Pharmaceutical Sciences, 2014Co-Authors: Rahul V. Haware, Ramya Shivagari, Paul R. Johnson, Scott Staton, William C. Stagner, Mali Ram GuptaAbstract:This work distinguishes and quantifies the effects of bovine- and vegetable-derived magnesium stearate (MgSt) molecular and macroscopic properties on lubrication efficiency using multivariate analysis. Principal component analysis (PCA) and partial least-square regression (PLS) were used to evaluate and quantify the lubricant effectiveness on a model tablet formulation. PCA score and loading plots showed a separation of model formulations based on the MgSt sources, which indicated different bovine- and vegetable-derived MgSt lubrication potential. PLS quantified the MgSt molecular [Enthalpy of dehydration (ΔHd), Enthalpy of Melting (ΔHm), percent crystallinity, and moisture content] and macroscopic [particle size (d50 ), specific surface area (SSA-MgSt), and MgSt Hausner ratio (HF-MgSt)] properties, their interactions, and square effects on formulation powder flow and tableting properties relating to MgSt's lubrication effectiveness. For crystalline MgSt, moisture content, HF-MgSt, d50 , and SSA-MgSt showed a major influence on the lubrication efficiency compared with the other MgSt molecular properties (percent crystallinity, ΔHm, and ΔHd). Amorphous MgSt showed poor lubrication, and none of its molecular or macroscopic properties showed significant effects on lubrication efficiency.
Urszula Domanska - One of the best experts on this subject based on the ideXlab platform.
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the physicochemical properties and solubility of pharmaceuticals methyl xanthines
The Journal of Chemical Thermodynamics, 2014Co-Authors: Aneta Pobudkowska, Urszula Domanska, Justyna A KryskaAbstract:Abstract The aim of this study was to evaluate the physio-chemical properties and solubility of three pharmaceuticals (Phs): theophylline, 7-(β-hydroxyethyl) theophylline, and theobromine in binary systems in different solvents. The solvents used were water, ethanol, and 1-octanol. Score of the solubility of these substances is being important for their dissolution effect inside the cell, the transportation by body fluids and the penetration possibility of lipid membranes. The Phs were classified to the group of methyl xanthines, which contain purine in their structure. Although they are mainly obtained via chemical synthesis, they can be also found in natural ingredients such as cocoa beans and tea leaves. These drugs are mainly acting on the central nervous system but are also used in the treatment of asthma or blood vessels. Solubility of 7 (β-hydroxyethyl) theophylline and theophylline were tested using synthetic method. In case of theobromine, which solubility is very small in the solvents noted, the spectrophotometric method has been used to measure its solubility. After designating phase diagrams of each of the solubility in the bipolar system, the experimental points have been correlated with the equations: Wilson, NRTL, UNIQUAC. Results show that theophylline and its derivatives show the best solubility from all tested Phs. Another method also used during this study was the differential scanning calorimetry (DSC), which allowed designation of the thermal properties of Phs. The fusion temperature and the Enthalpy of Melting were measured. Unfortunately, it was not possible to determine the fusion temperature and Enthalpy of Melting of theobromine, because of the decomposition of Ph at high temperature. The important property tested was the constant acidity, to this end, the spectrophotometric method of Bates–Schwarzenbach was used. Unfortunately, with this method it was not possible to determine the value of pKa 7-(β-hydroxyethyl) theophylline. For other Phs, these values do not differ significantly from those proposed in the literature. Both awareness and knowledge of values of the drug pKa and solubility are important in Phs production. This allows the selection of a suitable solvent and allows estimation of the correct dose and its capacity to absorb in human body.
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effect of temperature and composition on the density viscosity surface tension and excess quantities of binary mixtures of 1 ethyl 3 methylimidazolium tricyanomethanide with thiophene
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013Co-Authors: Urszula Domanska, Marta Krolikowska, Kamila WalczakAbstract:Abstract Thermal properties of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tricyanomethanide, ([EMIM][TCM]), measured by the Differential scanning calorimetry (DSC) as glass transition temperature ( T g,1 ), heat capacity change at glass transition temperature (Δ C p(g),1 ), Melting temperature ( T fus ), Enthalpy of Melting (Δ H fus ), phase transition temperature ( T tr ), Enthalpy of phase transition (Δ tr H ) and decomposition temperature ( T d ) were presented. The density and viscosity for the binary mixtures containing [EMIM][TCM] and thiophene at six temperatures (298.15, 308.15, 318.15, 328.15, 338.15 and 348.15 K) and ambient pressure were reported. The density and viscosity as a function of temperature were tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. The density and viscosity variations with compositions were described by polynomials. Excess molar volumes were described by the Redlich–Kister polynomial expansion. Viscosity deviations were calculated and correlated by the Redlich–Kister polynomial expansions. The surface tensions of pure ionic liquid and binary mixtures of [EMIM][TCM] and thiophene were measured at atmospheric pressure at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15 K). The surface tension deviations were calculated and correlated by the Redlich–Kister polynomial expansion. The temperature dependence of interfacial tension was used to evaluate the excess surface energy, the surface Enthalpy, the critical temperature, parachor and speed of sound for pure ionic liquid. These measurements have been provided to complete information of the influence of temperature on physico-chemical properties for the selected IL, which was chosen as a possible new entrainer in the separation of sulfur compounds from fuels. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that ionic liquid interactions with alcohols are strong dependent on the special trend of packing effects and hydrogen bonding of this ionic liquid with polar solvent.
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pka and solubility of drugs in water ethanol and 1 octanol
Journal of Physical Chemistry B, 2009Co-Authors: Urszula Domanska, Aneta Pobudkowska, Aleksandra Pelczarska, Pawel GieryczAbstract:Dissociation constants and corresponding pKa values of five drugs were obtained with the Bates−Schwarzenbach method using a Perkin-Elmer Lambda 35 UV/vis spectrophotometer at temperature 298.15 K in the buffer solutions. Atropine, promethazine hydrochloride, ibuprofen, flurbiprofen, and meclofenamic acid sodium salt exhibited pKa values of 10.3, 6.47, 5.38, 4.50, and 4.39, respectively. The equilibrium mole fraction solubilities of six drugs were measured in a range of temperatures from 240 to 340 K in three important solvents for drugs: water, ethanol, and 1-octanol using the dynamic method. The basic thermal properties of pure drugs, i.e., Melting and glass-transition temperatures, as well as the Enthalpy of Melting and the molar heat capacity at glass transition (at constant pressure) have been measured with the differential scanning microcalorimetry technique (DSC). Molar volumes have been calculated with the Barton group contribution method. The experimental solubility data have been correlated by me...
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phase equilibria study in binary systems tetra n butylphosphonium tosylate ionic liquid 1 alcohol or benzene or n alkylbenzene
Journal of Physical Chemistry B, 2008Co-Authors: Urszula Domanska, Kamil PaduszynskiAbstract:Ambient pressure (solid + liquid) equilibria (SLE) and (liquid + liquid) equilibria (LLE) of binary systems--ionic liquid (IL) tetra- n-butylphosphonium p-toluenesulfonate + 1-alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol, or 1-dodecanol), benzene, or n-alkylbenzene (toluene, ethylbenzene, n-propylbenzene)-have been determined by using dynamic method in a broad range of mole fractions and temperatures from 250 to 335 K. For binaries containing alcohol, simple eutectic diagrams were observed with complete miscibility in the liquid phase. Only in the case of system [IL + n-propylbenzene] was mutual immiscibility with an upper critical solution temperature (UCST) with low solubility of the IL in the alcohol and high solubility of the alcohol in the IL detected. The basic thermal properties of pure IL, i.e., Melting and glass-transition temperatures as well as Enthalpy of Melting, have been measured with differential scanning microcalorimetry technique (DSC). Well-known UNIQUAC, Wilson, NRTL, NRTL1, and NRTL2 equations have been fitted to obtain experimental data sets. For the system containing immiscibility gap [IL + n-propylbenzene], parameters of the equations have been derived only from SLE data. As a measure of goodness of correlations, root-mean square deviations of temperature have been used. These experimental results were compared to the previously measured binary systems with tetra- n-butylphosphonium methanesulfonate. Changing anion from methanesulfonate to p-toluenesulfonate decreases solubilities in systems with alcohols and increases the solubilities in binary systems with benzene and alkylbenzenes.
A L Greer - One of the best experts on this subject based on the ideXlab platform.
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extreme rejuvenation and softening in a bulk metallic glass
Nature Communications, 2018Co-Authors: J Pan, Yongzhao Wang, Qiang Guo, Dan Zhang, A L GreerAbstract:Rejuvenation of metallic glasses, bringing them to higher-energy states, is of interest in improving their plasticity. The mechanisms of rejuvenation are poorly understood, and its limits remain unexplored. We use constrained loading in compression to impose substantial plastic flow on a zirconium-based bulk metallic glass. The maximum measured effects are that the hardness of the glass decreases by 36%, and its excess Enthalpy (above the relaxed state) increases to 41% of the Enthalpy of Melting. Comparably high degrees of rejuvenation have been reported only on microscopic scales at the centre of shear bands confined to low volume fractions. This extreme rejuvenation of a bulk glass gives a state equivalent to that obtainable by quenching the liquid at ~1010 K s-1, many orders of magnitude faster than is possible for bulk specimens. The contrast with earlier results showing relaxation in similar tests under tension emphasizes the importance of hydrostatic stress.
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extreme rejuvenation and softening in a bulk metallic glass
Nature Communications, 2018Co-Authors: Yongchao Wang, A L Greer, Dabing Zhang, Yingfeng LiAbstract:Rejuvenation of metallic glasses, bringing them to higher-energy states, is of interest in improving their plasticity. The mechanisms of rejuvenation are poorly understood, and its limits remain unexplored. We use constrained loading in compression to impose substantial plastic flow on a zirconium-based bulk metallic glass. The maximum measured effects are that the hardness of the glass decreases by 36%, and its excess Enthalpy (above the relaxed state) increases to 41% of the Enthalpy of Melting. Comparably high degrees of rejuvenation have been reported only on microscopic scales at the centre of shear bands confined to low volume fractions. This extreme rejuvenation of a bulk glass gives a state equivalent to that obtainable by quenching the liquid at ~1010 K s–1, many orders of magnitude faster than is possible for bulk specimens. The contrast with earlier results showing relaxation in similar tests under tension emphasizes the importance of hydrostatic stress. Deforming metallic glasses can rejuvenate them to higher energy states, but only in the shear bands where deformation is usually concentrated. Here, the authors use a notched setup to suppress shear banding and promote significant bulk softening of a zirconium-based metallic glass.
Marta Krolikowska - One of the best experts on this subject based on the ideXlab platform.
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solid liquid and liquid liquid phase equilibria of il water binary systems the influence of the ionic liquid structure on mutual solubility
Fluid Phase Equilibria, 2014Co-Authors: Marta KrolikowskaAbstract:Abstract In this work binary (solid + liquid) and (liquid + liquid) phase equilibria measurements for the new ionic liquids: 1-ethyl-3-methylimidazolium tricyanomethanide, [EMIM][TCM], 1-butyl-3-methylimidazolium tricyanomethanide, [BMIM][TCM], 1-butyl-1-methyl-pyrrolidinium tricyanomethanide, [BMPYR][TCM], 1-butyl-1-methylmorpholinium tricyanomethanide, [BMMOR][TCM], trihexyltertadecylphosphonium tricyanomethanide, [P6,6,6,14][TCM] with water over a wide temperature range and at atmospheric pressure have been determined using dynamic method. In order to discuss the influence of the ionic liquid structure on mutual miscibility with water the phase equilibria for 1-butyl-1-methyl-pyrrolidinium trifluoromethanesulfonate, [BMPYR][CF3SO3], 1-butyl-1-methylpyrrolidinium tetracyanoborate, [BMPYR][TCB] and 1-butyl-3-methylimidazolium dicyanamide, [BMIM] [DCA] were detected. For the tested binary systems with immiscibility gap the parameters of the LLE correlation have been derived using the NRTL equation. For the binary mixtures of water and [EMIM][TCM], [BMIM][DCA] and [BMPYR][CF3SO3] the complete miscibility in the liquid phase over whole composition range was observed. For these systems the (solid + liquid) phase equilibria have been correlated by means of NRTL, UNIQUAC and Wilson equations. The influence of the ionic liquid structure on water solubility was discussed. Additionally the basic thermal characterization of pure ionic liquids that is: the glass transition temperature, the change of heat capacity at the glass-transition temperature, temperature and Enthalpy of phase transition and temperature and Enthalpy of Melting were determined using DSC technique. Decomposition temperature was detected by thermograwimetry.
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effect of temperature and composition on the density viscosity surface tension and excess quantities of binary mixtures of 1 ethyl 3 methylimidazolium tricyanomethanide with thiophene
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013Co-Authors: Urszula Domanska, Marta Krolikowska, Kamila WalczakAbstract:Abstract Thermal properties of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tricyanomethanide, ([EMIM][TCM]), measured by the Differential scanning calorimetry (DSC) as glass transition temperature ( T g,1 ), heat capacity change at glass transition temperature (Δ C p(g),1 ), Melting temperature ( T fus ), Enthalpy of Melting (Δ H fus ), phase transition temperature ( T tr ), Enthalpy of phase transition (Δ tr H ) and decomposition temperature ( T d ) were presented. The density and viscosity for the binary mixtures containing [EMIM][TCM] and thiophene at six temperatures (298.15, 308.15, 318.15, 328.15, 338.15 and 348.15 K) and ambient pressure were reported. The density and viscosity as a function of temperature were tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. The density and viscosity variations with compositions were described by polynomials. Excess molar volumes were described by the Redlich–Kister polynomial expansion. Viscosity deviations were calculated and correlated by the Redlich–Kister polynomial expansions. The surface tensions of pure ionic liquid and binary mixtures of [EMIM][TCM] and thiophene were measured at atmospheric pressure at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15 K). The surface tension deviations were calculated and correlated by the Redlich–Kister polynomial expansion. The temperature dependence of interfacial tension was used to evaluate the excess surface energy, the surface Enthalpy, the critical temperature, parachor and speed of sound for pure ionic liquid. These measurements have been provided to complete information of the influence of temperature on physico-chemical properties for the selected IL, which was chosen as a possible new entrainer in the separation of sulfur compounds from fuels. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that ionic liquid interactions with alcohols are strong dependent on the special trend of packing effects and hydrogen bonding of this ionic liquid with polar solvent.
Rahul V. Haware - One of the best experts on this subject based on the ideXlab platform.
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application of multivariate methods to evaluate the functionality of bovine and vegetable derived magnesium stearate
Journal of Pharmaceutical Sciences, 2014Co-Authors: Rahul V. Haware, Ramya Shivagari, Paul R. Johnson, Scott Staton, William C. Stagner, Mali Ram GuptaAbstract:ABSTRACT This work distinguishes and quantifies the effects of bovine- and vegetable-derived magnesium stearate (MgSt) molecular and macroscopic properties on lubrication efficiency using multivariate analysis. Principal component analysis (PCA) and partial least-square regression (PLS) were used to evaluate and quantify the lubricant effectiveness on a model tablet formulation. PCA score and loading plots showed a separation of model formulations based on the MgSt sources, which indicated different bovine- and vegetable-derived MgSt lubrication potential. PLS quantified the MgSt molecular [Enthalpy of dehydration (ΔHd), Enthalpy of Melting (ΔHm), percent crystallinity, and moisture content] and macroscopic [particle size ( d 50 ), specific surface area (SSA-MgSt), and MgSt Hausner ratio (HF-MgSt)] properties, their interactions, and square effects on formulation powder flow and tableting properties relating to MgSt's lubrication effectiveness. For crystalline MgSt, moisture content, HF-MgSt, d 50 , and SSA-MgSt showed a major influence on the lubrication efficiency compared with the other MgSt molecular properties (percent crystallinity, ΔHm, and ΔHd). Amorphous MgSt showed poor lubrication, and none of its molecular or macroscopic properties showed significant effects on lubrication efficiency. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
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application of multivariate methods to evaluate the functionality of bovine and vegetable derived magnesium stearate
Journal of Pharmaceutical Sciences, 2014Co-Authors: Rahul V. Haware, Ramya Shivagari, Paul R. Johnson, Scott Staton, William C. Stagner, Mali Ram GuptaAbstract:This work distinguishes and quantifies the effects of bovine- and vegetable-derived magnesium stearate (MgSt) molecular and macroscopic properties on lubrication efficiency using multivariate analysis. Principal component analysis (PCA) and partial least-square regression (PLS) were used to evaluate and quantify the lubricant effectiveness on a model tablet formulation. PCA score and loading plots showed a separation of model formulations based on the MgSt sources, which indicated different bovine- and vegetable-derived MgSt lubrication potential. PLS quantified the MgSt molecular [Enthalpy of dehydration (ΔHd), Enthalpy of Melting (ΔHm), percent crystallinity, and moisture content] and macroscopic [particle size (d50 ), specific surface area (SSA-MgSt), and MgSt Hausner ratio (HF-MgSt)] properties, their interactions, and square effects on formulation powder flow and tableting properties relating to MgSt's lubrication effectiveness. For crystalline MgSt, moisture content, HF-MgSt, d50 , and SSA-MgSt showed a major influence on the lubrication efficiency compared with the other MgSt molecular properties (percent crystallinity, ΔHm, and ΔHd). Amorphous MgSt showed poor lubrication, and none of its molecular or macroscopic properties showed significant effects on lubrication efficiency.