Size dependence of the solubility of nonpolar compounds in different solvents

2002 ◽  
Vol 80 (4) ◽  
pp. 401-412 ◽  
Author(s):  
Giuseppe Graziano
Keyword(s):  
Organic Solvents ◽  
Noble Gases ◽  
Molecular Size ◽  
Volume Effect ◽  
Aliphatic Hydrocarbons ◽  
Negative Slope ◽  
Solvent Interactions ◽  
Standard Gibbs Energy Change ◽  
Two Factors ◽  
The Difference

At 25°C, plots of the standard Gibbs energy change associated with the solvation of noble gases and aliphatic hydrocarbons vs. the size of the solutes prove to be approximately linear with a negative slope for common organic solvents but not for water. In the latter case, the plot has a characteristic V-shape. The slope is negative for noble gases, methane, and ethane, but is positive for larger alkanes. This means that the solubility of nonpolar solutes increases with solute size in every solvent except water. The solvation thermodynamics of noble gases and aliphatic hydrocarbons in five solvents (water, ethanol, benzene, c-hexane, and n-hexane) are analyzed in detail by a general theory, which is rederived to avoid risky misunderstandings. The calculations are performed in the same manner for all solvents, using simple formulas where the physical reliability is well established and the results are consistent. The work of cavity creation increases with solute size in every solvent, but to a far greater extent in water. Additionally, the work to turn on the solute–solvent attractive interactions increases in magnitude with solute size in every solvent, but to a lesser extent in water. By combining these two factors a satisfactory explanation for experimental data obtained emerges. The microscopic origins of the difference between water and common organic solvents are discussed.Key words: solvation, excluded-volume effect, solute–solvent interactions, enthalpy–entropy compensation, molecular size.

Slow Down You’re Moving Too Fast

2015 ◽  
Vol 27 (2) ◽  
pp. 53-63 ◽  
Author(s):  
Annie Lang ◽  
Nancy Schwartz ◽  
Sharon Mayell
Keyword(s):  
Older Adults ◽  
Cognitive Aging ◽  
Attention And Memory ◽  
Younger Adults ◽  
Media Messages ◽  
Two Factors ◽  
The Difference

The study reported here compared how younger and older adults processed the same set of media messages which were selected to vary on two factors, arousing content and valence. Results showed that older and younger adults had similar arousal responses but different patterns of attention and memory. Older adults paid more attention to all messages than did younger adults. However, this attention did not translate into greater memory. Older and younger adults had similar levels of memory for slow-paced messages, but younger adults outperformed older adults significantly as pacing increased, and the difference was larger for arousing compared with calm messages. The differences found are in line with predictions made based on the cognitive-aging literature.

In the stability of paints and varnishes for protective and decorative wood finish

2016 ◽  
Author(s):  
Ю.И. Цой
Keyword(s):  
Organic Solvents ◽  
Evaluation Criteria ◽  
Ternary Systems ◽  
Solubility Parameters ◽  
Formaldehyde Resin ◽  
Film Forming ◽  
The Difference ◽  
Molecular Forces ◽  
The Stability ◽  
Thermodynamic Interaction

Задача получения однородного состава ЛКМ сводится к правильному выбору пленкообразователей и соответствующих растворителей и, в случае необходимости, разбавителей и добавок. На основе положений теории растворимости была проведена оценка совместимости компонентов и стабильности таких систем. Критериями оценки были приняты параметры растворимости и термодинамического взаимодействия. Исследовали совместимость алкидных лаков с аминоформальдегидными смолами в бутаноле, и результаты этих исследований представлены в треугольной фазовой диаграмме. Для оценки совместимости смол по результатам расчета параметров термодинамического взаимодействия были построены спинодали для тройных систем. Как показывает анализ результатов проведенных исследований, даже при большой разности ?? = |?12 – ?13| = 0,2 наблюдается небольшая область несовместимости. С уменьшением разности ?? область несовместимости сужается. При ?23 > ?с область несовместимости расширяется как для ? = 0,2, так и для ?? = 0,1 и ?? = 0. Таким образом, для таких систем на совместимость компонентов, в первую очередь, влияет их взаимодействие между собой – чем оно больше, тем лучше они совместимы. Проведенные исследования показали, что парциальные параметры растворимости, учитывающие природу когезионных сил, более объективно характеризуют растворимость пленкообразующих смол в органических растворителях, чем их общий параметр растворимости. Растворимость пленкообразующих алкидных и этерифицированных аминоформальдегидных смол в органических растворителях обусловлена термодинамическим взаимодействием молекулярных сил различной природы. Стабильность смеси алкидной и этерифицированной аминоформальдегидной смолы в бутаноле обусловлена в большей степени термодинамическим взаимодействием молекулярных сил; при этом степень бутанолизации меламиноформальдегидной смолы оказывает наибольшее влияние на стабильность cистемы. Проведенные исследования по стабильности лакокрасочных смесей из различных пленкообразующих смол на основе рассмотренных критериев оценки могут быть использованы для совершенствования технологии защитно-декоративной отделки древесины. The problem of obtaining a homogeneous composition of the coatings is reduced to the proper selection of film-forming agents, and diluent and, if appropriate, diluents and additives. On the basis of the theory of solubility, we have carried out the assessment of the compatibility of the components and stability of such systems. The evaluation criteria were adopted the parameters of the solubility and thermodynamic interaction. Researched the compatibility with alkyd varnishes aminoformaldehyde resin in butanol, and the results of these studies are presented in the triangular phase diagram. To evaluate the compatibility of the resins according to the results of calculation of thermodynamic parameters of interaction were built spinodal for ternary systems. As the analysis of the results of the studies, even when the difference ??|?12 – ?13| = 0,2 there is a small area of incompatibility. With the decrease of the difference ? ? region incompatibility narrows. When ?23> ?с region incompatibility extends to ?? = 0,2, and for ?? = 0.1 and ?? = 0. Thus, for such systems, compatibility of components, primarily, affects their interaction with each other – the further away it is, the better they are compatible. Studies have shown that the partial solubility parameters, which take into account the nature of cohesive forces, more objectively characterize the solubility of film-forming resins in organic solvents than their total solubility parameter. The solubility and film-forming aminoformaldehyde esterified alkyd resins in organic solvents due to thermodynamic interaction of molecular forces of different nature. Тhe stability of the mixture and aminoformaldehyde esterified alkyd resin in butanol is generated largely by thermodynamic forces of molecular interaction; the degree of butanolate melamine-formaldehyde resin has the greatest effect on the stability of the system. Conducted research on the stability of the paint mixtures of various film-forming resins on the basis of the evaluation criteria can be used to improve the technology of protective and decorative wood finish.

scholarly journals An experimental and theoretical investigation of diffusion in a two-phase alloy

1948 ◽  
Vol 192 (1031) ◽  
pp. 575-592 ◽  
Keyword(s):  
Free Energy ◽  
Single Phase ◽  
Phase State ◽  
Theoretical Treatment ◽  
Research Association ◽  
Essential Difference ◽  
Two Phase ◽  
Two Factors ◽  
Order Of Magnitude ◽  
The Difference

The present paper describes an investigation of diffusion in the solid state. Previous experimental work has been confined to the case in which the free energy of a mixture is a minimum for the single-phase state, and diffusion decreases local differences of concentration. This may be called ‘diffusion downhill’. However, it is possible for the free energy to be a minimum for the two-phase state; diffusion may then increase differences of concentration; and so may be called ‘diffusion uphill’. Becker (1937) has proposed a simple theoretical treatment of these two types of diffusion in a binary alloy. The present paper describes an experimental test of this theory, using the unusual properties of the alloy Cu 4 FeNi 3 . This alloy is single phase above 800° C and two-phase at lower temperatures, both the phases being face-centred cubic; the essential difference between the two phases is their content of copper. On dissociating from one phase into two the alloy develops a series of intermediate structures showing striking X-ray patterns which are very sensitive to changes of structure. It was found possible to utilize these results for a quantitative study of diffusion ‘uphill’ and ‘downhill’ in the alloy. The experimental results, which can be expressed very simply, are in fair agreement with conclusions drawn from Becker’s theory. It was found that Fick’s equation, dc / dt = D d2c / dx2 , can, within the limits of error, be applied in all cases, with the modification that c denotes the difference of the measured copper concentration from its equilibrium value. The theory postulates that D is the product of two factors, of which one is D 0f the coefficient of diffusion that would be measured if the alloy were an ideal solid solution. The theory is able to calculate D/D 0 , if only in first approximation, and the experiments confirm this calculation. It was found that in most cases the speed of diffusion—‘uphill’ or ‘downhill’—has the order of magnitude of D 0 . * Now with British Electrical Research Association.

The opposite and antagonistic effects of the closely related POU family transcription factors Brn-3a and Brn-3b on the activity of a target promoter are dependent on differences in the POU domain

1994 ◽  
Vol 14 (10) ◽  
pp. 6907-6914
Author(s):  
P J Morris ◽  
T Theil ◽  
C J Ring ◽  
K A Lillycrop ◽  
T Moroy ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Promoter Activity ◽  
Group Iv ◽  
Promoter Activation ◽  
Antagonistic Effects ◽  
Pou Domain ◽  
Close Relationship ◽  
Two Factors ◽  
The Difference ◽  
Target Promoter

The Brn-3a, Brn-3b, and Brn-3c POU family transcription factors are closely related to one another and are members of the group IV subfamily of POU factors. Here we show that despite this close relationship, the factors have different effects on the activity of a target promoter: Brn-3a and Brn-3c stimulate the promoter whereas Brn-3b represses it. Moreover, Brn-3b can antagonize the stimulatory effect of Brn-3a on promoter activity and can also inhibit promoter activation by the Oct-2.1 POU factor. The difference in the transactivation activities of Brn-3a and Brn-3b is dependent upon the C-terminal region containing the POU domain of the two proteins, since exchange of this domain between the two factors converts Brn-3a into a repressor and Brn-3b into an activator.

scholarly journals Iodination of insulin in aqueous and organic solvents

1969 ◽  
Vol 115 (1) ◽  
pp. 11-18 ◽  
Author(s):  
A. Massaglia ◽  
U. Rosa ◽  
G. Rialdi ◽  
C. A. Rossi
Keyword(s):  
Ethylene Glycol ◽  
Organic Solvents ◽  
Molecular Conformation ◽  
Aqueous Media ◽  
Native Structure ◽  
Experimental Conditions ◽  
Polar Environment ◽  
Polar Area ◽  
The Difference ◽  
A Chain

1. The iodination of insulin was studied under various experimental conditions in aqueous media and in some organic solvents, by measuring separately the uptake of iodine by the four tyrosyl groups and the relative amounts of monoiodotyrosine and di-iodotyrosine that are formed. In aqueous media from pH1 to pH9 the iodination occurs predominantly on the tyrosyl groups of the A chain. Some organic solvents increase the iodine uptake of the B-chain tyrosyl groups. Their efficacy in promoting iodination of Tyr-B-16 and Tyr-B-26 is in the order: ethylene glycol and propylene glycol≃methanol and ethanol>dioxan>8m-urea. 2. It is suggested that each of the four tyrosyl groups in insulin has a different environment: Tyr-A-14 is fully exposed to the solvent; Tyr-A-19 is sterically influenced by the environmental structure, possibly by the vicinity of a disulphide interchain bond; Tyr-B-16 is embedded into a non-polar area whose stability is virtually independent of the molecular conformation; Tyr-B-26 is probably in a situation similar to Tyr-B-16 with the difference that its non-polar environment depends on the preservation of the native structure.

scholarly journals Using Generalized Procrustes Analysis for Evaluation of Sensory Characteristic Data of Lamb Meat

2019 ◽  
Vol 7 (6) ◽  
pp. 840
Author(s):  
Gazel Ser
Keyword(s):  
Procrustes Analysis ◽  
Fasting Period ◽  
Multivariate Statistic ◽  
Generalized Procrustes Analysis ◽  
Alfalfa Hay ◽  
Two Factors ◽  
Total Variability ◽  
Sensory Analyses ◽  
The Difference ◽  
Meat Samples

Generalized Procrustes Analysis (GPA) is a multivariate statistic method that is used at the evaluation of sensory analyses in the food industry. GPA provides benefit in terms of decreasing the difference between the panellists and bringing the data obtained from different panellists together. In this study, the aim was to determine the effect of a pre-slaughter fasting period on sensory characteristics of lambs fed with different rations using GPA. Semi-trained panellists formed from twenty-six persons were requested for evaluation of the meat samples such as tenderness, juiciness, flavour and overall liking rated on a scale of 1(extremely dislike) to 9 (extremely good). The first two factors obtained by GPA explained 66.74% of total variability. As a result of the analysis, it was determined that 12 h and 24 h fasting of lambs fed barley supplemented with alfalfa hay were less preferable when compared to lambs fed alfalfa hay only. In addition, lambs in both groups with 48 h fasting were preferred less by the panellists. In conclusion, GPA analysis provides useful data concerning the sensitivity of each panellist in a sensory panel test.

Blood Pressure Estimation with Considering of Stroke Volume Effect

2008 ◽  
pp. 173-180
Author(s):  
Moha’med O. Al-Jaafreh ◽  
Adel A. Al-Jumaily
Keyword(s):  
Blood Pressure ◽  
Stroke Volume ◽  
Applied Pressure ◽  
Peripheral Resistance ◽  
Volume Effect ◽  
Signal Features ◽  
Measure Blood Pressure ◽  
The Mean ◽  
The Difference ◽  
Blood Pressure Estimation

The mean arterial pressure (MAP) is a very important cardiovascular parameter for physicians to diagnose various cardiovascular diseases. Many algorithms were used to estimate MAP with different accuracy. These algorithms used different factors, such as blood level, pulses, and external applied pressure, photo-plethysmography (PPG) signal features, heart rate (HR), and other factors. In addition, some natural-based techniques were employed to minimize the difference between estimated and measured blood pressure, as well as to measure blood pressure continuously. This article presents an algorithm to estimate MAP, utilizing the HR, Stroke Volume (SV), and Total Peripheral Resistance (TPR), with considering SV changing influence; this consideration is investigated mathematically, and by the Particle Swarm Optimization (PSO) technique.

The difference model of disability: A change in direction for vocational rehabilitation practice

2020 ◽  
Vol 26 (1) ◽  
pp. 12-17
Author(s):  
Jonathon S. Breen ◽  
Susan Forwell
Keyword(s):  
Vocational Rehabilitation ◽  
Social Forces ◽  
Job Seekers ◽  
Difference Model ◽  
Models Of Disability ◽  
The Social ◽  
Two Factors ◽  
Employment Goals ◽  
The Difference ◽  
The Individual

AbstractVocational rehabilitation provides guidance and support to individuals with disabilities entering the workforce. Employment plans include considerations of goals, the job market, and pre-existing or trainable skills on the part of job seekers. This process also includes an understanding of the social forces that affect employment goals. Current models of disability include the medical, social, and embodiment models. Each is cognitively based and assumes an element of responsibility or blame, that is, respectively, focused on the individual with a disability, the community, or a combination of these two factors. The difference model of disability offers an alternative understanding of disability by providing an affect-based framework that eliminates the premise of blame. This conceptualization of disability provides a new approach to vocational rehabilitation.

Response of alveolar epithelial solute permeability to changes in lung inflation

1980 ◽  
Vol 49 (6) ◽  
pp. 1032-1036 ◽  
Author(s):  
E. A. Egan
Keyword(s):  
Pore Radius ◽  
Alveolar Epithelium ◽  
Molecular Size ◽  
High Volume ◽  
Lung Inflation ◽  
Solute Permeability ◽  
Alveolar Epithelial ◽  
The Difference ◽  
Total Capacity ◽  
Inflation Volume

The relation between the solute permeability of th alveolar epithelium, characterized as a pore radius, and lung inflation was studied in anesthetized dogs. Pore radius was calculated from measurements of the rate of efflux of several radiolabeled solutes of known molecular size from alveolar saline. Individual animals were studied at two or more separate inflation volumes. The pore radius during the first volume studied averaged 20 A in high-volume animals (mean inflation 82% of capacity) and 15 A at lower volume (mean inflation, 47% of capacity). The difference was significantly P < 0.05. Lungs inflated to total capacity showed free solute movement across the lung epithelium. Increasing inflation volume in an animal always produced a larger pore radius. Decreasing the inflation volume did not produce a smaller pore radius; it remained the same or became larger. Volume induced increases in lung epithelial solute permeability do not reverse immediately at lower volumes, suggesting this phenomenon represents lung injury.

scholarly journals Investigation of the Microcharacteristics of Asphalt Mastics under Dry–Wet and Freeze–Thaw Cycles in a Coastal Salt Environment

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2627 ◽  
Author(s):  
Qinling Zhang ◽  
Zhiyi Huang
Keyword(s):  
Salt Spray ◽  
Molecular Size ◽  
Gel Permeation Chromatography ◽  
Surface Phenomenon ◽  
High Concentration ◽  
Force Microscopy ◽  
Freeze Thaw ◽  
Two Factors ◽  
Asphalt Mastics ◽  
Styrene Butadiene

In the coastal areas of southeastern China, high temperatures and humidity in the summer and microfreezing in the winter, as well as a high concentration of salt spray in the environment, seriously deteriorate the durability of asphalt mixtures. Therefore, the microcharacteristics of asphalt mastics (asphalt mixed with mineral filler) under the effect of chlorine salt and “dry–wet and freeze–thaw” (DW-FT) cycles were investigated by Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and atomic force microscopy (AFM) techniques. Two factors, including asphalt mastic types (base and styrene-butadiene-styrene (SBS)-modified mastics) and numbers of DW-FT cycles, were considered based on the natural environment. Regression functions were established to explore the relationship between the FTIR, GPC, and AFM indexes. The results indicate that there were no chemical reactions between the asphalt and filler because the infrared spectrum of the base and SBS-modified mastics were similar. With the increase of the salt “DW-FT” cycle numbers, the sulfoxide index and large molecular size ratios ( L M S % ) increased, and the surface roughness ( R q and R a ) of the morphology decreased, as illustrated by a flatting mastics surface phenomenon in the AFM test. Regression analysis confirmed that there was a high correlation between the FTIR, GPC, and AFM indexes, and formation of the bee structures was closely related to the long chain index. The SBS-modified mastics had a better antiaging performance with a lower increase in the sulfoxide index after the salt “DW-FT” cycles in the coastal environment.

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