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1.
Front Public Health ; 12: 1352646, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38966702

RESUMO

Introduction: Attention to work addiction risk is growing; however, more studies are needed to explore the possible impact of work addiction risk on various aspects of employees' work and life domains. Although several studies have considered the antecedents or consequences of work addiction risk, this study particularly focuses on sleep quality as a potential explanatory underlying mechanism in the relation between work addition risk and three outcome variables including stress at home, stress at work and well-being. Method: The data was collected using an online platform and participants consisted of 188 French employees who were selected using simple random sampling method. Participants responded to the survey including the Work Addiction Risk Test (WART), stress at work, well-being, and sleep quality. The data was analyzed using JASP and SPSS-26 programs. Results: The results revealed that there are significant positive relationships between work addiction risk and both stress at home and at work and negative relationships between work addiction risk and both sleep quality and well-being. In addition, the analyses of the mediation paths suggest the significant mediation role of sleep quality for the link between work addition risk and stress at work as well as the link between work addiction risk and well-being. Discussion: Given the verified mediating role of sleep quality in the relationship between work addiction, stress and wellbeing, it is recommended that organizations and companies pay particular attention to their employees' sleep quality.


Assuntos
Comportamento Aditivo , Qualidade do Sono , Humanos , Feminino , Masculino , Adulto , Inquéritos e Questionários , Pessoa de Meia-Idade , Comportamento Aditivo/psicologia , França , Estresse Psicológico/psicologia , Estresse Ocupacional/psicologia , Fatores de Risco , Local de Trabalho/psicologia
2.
Langmuir ; 40(9): 4635-4645, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38377565

RESUMO

Quartz is ubiquitous in subsurface formations. The crystal faces have different atomic arrangements. Knowledge of the molecular structures on the surface of quartz is key in many processes. Molecular dynamics simulations are conducted to investigate the atomic arrangement effect on the water film structure, ion adsorption, and wettability at three different α-quartz surfaces. The interfacial structures depend on the quartz surface. Intrasurface hydrogen bonding between surface silanols differs in the α-quartz surface. At the (0001) surface, the OH density is 9.58 nm-2, consisting of Q2 units with two hydroxyl groups per silicone atom. At the (101̅0)-ß surface, the OH density is 7.54 nm-2, consisting of Q3 units with one hydroxyl group per silicone atom; there is significant intrasurface hydrogen bonding. At the (101̅0)-α surface, the OH density is 7.54 nm-2, consisting of Q2 units; however, there is little intrasurface hydrogen bonding. The intrasurface hydrogen bonding results in the exposure of hydrogen-bond acceptors to the aqueous phase, causing water molecules to have an H-up (hydrogen toward surface) orientation. This orientation can be found at the (0001) and (101̅0)-ß surfaces; it is related to the degree of ordering at the surface. The ordering at the (0001) and (101̅0)-ß surfaces is higher than that at the (101̅0)-α surface. In aqueous systems with ions, cation adsorption is the most dominant at the (0001) surface due to the largest surface density of the intrasurface hydrogen bonding, providing interaction sites for cations to be adsorbed. We observe a pronounced decrease in water film thickness from the ions at the (0001) surface only, likely due to significant cation adsorption. In this work, we demonstrate that the hydrogen-bond network, which varies from the plane cut, affects the water film structure and ion adsorption. The contact is nearly zero despite the changes in the film thickness and molecular structure at the temperature of 318 K.

3.
J Phys Chem B ; 127(46): 10043-10051, 2023 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-37943742

RESUMO

Accurate computation of shear viscosity is fundamental for describing fluid flow and designing and developing new processes. Poly-α-olefins (PAO's), particularly from 1-decene, have been applied to a variety of industrial processes. Recently, these molecules have been applied as carbon dioxide thickeners, enhancing carbon dioxide viscosity, which is important in carbon dioxide injection, either for enhanced oil recovery or sequestration in geological formations. For these applications, knowledge of the pure oligomer viscosity is crucial to design and operate the oligomer upstream pipelines before mixing them with carbon dioxide. Using Green-Kubo formalism with equilibrium molecular dynamics simulations, two methods are presented in the literature to generate the traceless, symmetric pressure tensor. In this work, we show that these two methods provide different values of shear viscosity, from the analysis of how the diagonal components of the traceless, symmetric pressure tensor are computed in each method. Then, we examine the consistency and correctness of each method: one is found to be consistent. The other is corrected by scaling the fluctuations of the diagonal components. Shear viscosities of supercritical carbon dioxide, vapor and liquid n-pentane, and liquid n-decane are computed to illustrate the analysis. We also apply the consistent method to compute the viscosity of 1-decene oligomers, including for the first time larger-than-dimer oligomers (trimer, tetramer, hexamer, and decamer).

4.
PNAS Nexus ; 2(11): pgad393, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38024406

RESUMO

Most compounds of some 1,000 amu molecular weight (MW) and higher are poorly soluble in carbon dioxide (CO2). Only at very high pressure, there may be mild solubility. This limits the use of CO2 as a solvent and modifications of CO2 properties through additives. We have developed a coarse-grained molecular model to investigate the dependency of the solubility of hydrocarbon oligomers (MW of ∼1,000 amu) in CO2 and on the molecular structure. The coarse-grained model is optimized by the particle swarm optimization algorithm to reproduce density, surface tension, and enthalpy of vaporization of a highly branched hydrocarbon oligomer (poly-1-decene with six repeating units). We demonstrate that branching in molecular structure of oligomers significantly increases solubility in CO2. The branching in molecular structure results in up to 270-time enhancement of solubility in CO2 than an n-alkane with the same MW. The number of structural edges (methyl group) is a key in improved CO2-philicity. The solubility of poly-1-decene with nine repeating units (MW of 1,264.4 amu) is higher in CO2 than poly-1-dodecene with six repeating units (MW of 1,011.93 amu) because it has more structural edges (10 vs. 7). These results shed light on the enhancement of CO2-philicity by altering molecular structure rather than modifying chemical composition in compounds.

5.
BMC Psychol ; 11(1): 294, 2023 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-37759258

RESUMO

BACKGROUND: Some individuals may manifest psychotic symptoms that do not fulfill the requisite clinical criteria for a formal diagnosis of psychosis. The assessment of susceptibility to delusions, encompassing both clinical and non-clinical cohorts, frequently makes use of the Peters et al. Delusions Inventory (PDI-40). This study aimed to evaluate the reliability and validity of the Persian version of Peters et al. Delusions Inventory (PDI-40) in Iranian non-clinical and clinical samples. METHODS: The present study employed a cross-sectional, correlational design in 2020. A total of 1402 Iranian participants were recruited for the study, which consisted of three distinct stages. The first stage involved an Exploratory Factor Analysis (EFA) conducted on a non-clinical sample of 512 participants. The second stage comprising different non-clinical sample 764 participants to perform a Confirmatory Factor Analysis (CFA). In the third stage, a clinical sample of 126 psychotic patients was compared to a non-clinical sample. All participants completed the PDI-40, the Community Assessment of Psychotic Experiences (CAPE-42), and the Depression, Anxiety, and Stress Scale (DASS-21). The internal structure of PDI-40 was examined through the analysis of its factor structure using LISREL 8.8. RESULTS: The EFA analysis unveiled nine components within Persian version of PDI-40. The CFA analysis demonstrated an excellent fit of the nine-factor structure of Persian PDI-40 to the data. The total score exhibited high internal reliability, as indicated by Cronbach's alpha coefficient of 0.92. Moreover, Persian PDI-40 exhibited satisfactory evidence of convergent validity, as significant correlations were observed between dimensions of PDI-40 and subscales of CAPE-42 and DASS-21. Lastly, findings indicated that psychotic participants scored higher than non-clinical participants in all components of the PDI-40(p < 0.05). CONCLUSION: Persian version of the PDI-40 demonstrates strong reliability and validity for assessing delusion proneness in both non-clinical and clinical samples in Iran. The observed distinctions between psychotic and non-clinical participants underscore its potential as a valuable tool for discerning delusion proneness in diverse contexts.


Assuntos
Ansiedade , Delusões , Humanos , Estudos Transversais , Delusões/diagnóstico , Irã (Geográfico) , Reprodutibilidade dos Testes , Ansiedade/diagnóstico
6.
Appl Neuropsychol Adult ; : 1-8, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-37318541

RESUMO

Internet use has grown substantially over the past decade. As a result, individuals are more at risk of developing internet addiction. Studies have shown that internet addiction results in neurocognitive dysfunctions. The current study aimed to compare the cognitive flexibility, inhibitory control, and working memory performance of internet-addicted, at-risk internet-addicted individuals and methamphetamine users to healthy participants using the Wisconsin card sorting task, n-back, and Stroop color and word test. The results showed no significant differences between at-risk internet-addicted and internet-addicted with the healthy group in the Wisconsin card sorting task and in the Stroop test. Surprisingly, the mean n-back accuracy was not significantly different between methamphetamine users and the internet-addicted group. The mean n-back accuracy in the internet-addicted group was significantly lower than that of healthy and at-risk internet addicts. In conclusion, working memory can be impaired under the influence of internet addiction. The results can lead to develop possible intervention programs aimed at prevention of internet addiction by helping individuals identify and modify their problematic use habits, reducing internet addiction and improving cognitive functioning.

7.
J Phys Chem B ; 127(12): 2749-2760, 2023 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-36930893

RESUMO

The components of a fluid mixture may segregate due to the Soret effect, a coupling phenomenon in which mass flux can be induced by a thermal gradient. In this work, we evaluate systematically the thermodiffusion of the CO2-H2O mixture, and the influence of the geothermal gradient on CO2 segregation in deep saline aquifers in CO2 storage. The eHeX method, a nonequilibrium molecular dynamics simulation approach, is judiciously selected to simulate the phenomenon. At 350 K, 400 bar, and CO2 mole fraction of 0.02 (aquifer conditions), CO2 accumulates on the cold side, and the thermal diffusion factor is close to 1 in a number of force fields. The lower the temperature, the higher is the separation and the thermal diffusion factor. In colder regions, water self-association is stronger, whereas the CO2-H2O cross-association and the CO2-CO2 interactions enhance at higher temperatures. Thermodiffusion and gravitational segregation have opposite effects on CO2 segregation. At typical subsurface conditions, the Soret effect is more pronounced than gravity segregation, and CO2 concentrates in the top (colder region). Our work sets the stage to model the effect of electrolytes on CO2 segregation in subsurface aquifers and other areas of interest.

8.
J Eat Disord ; 10(1): 158, 2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36357951

RESUMO

BACKGROUND: Food addiction at the individual level causes physical and mental health problems, impairs individuals' social functioning, and causes dysfunction in the family system. Therefore, a tool to identify this behavioral disorder is one of the health requirements of communities. This research aimed to investigate the psychometric assessment of the Persian translation of Yale Food Addiction Scale Version 2.0 (YFAS 2.0) in Iranian college students. METHOD: This research was cross-sectional descriptive, and 451 students were selected by convenience sampling method. Yale Food Addiction Scale Version 2.0 (YFAS 2.0), Depression, Anxiety, and Stress Scale-21 (DASS-21), and Food Craving Questionnaire-Trait, reduced (FCQ-T-r) were used to collect data. RESULTS: The confirmatory factor analysis indicated that single-factor model provides a good fit to data (SRMR = 0.078; CFI = 0.94; NFI = 0.92; IFI = 0.94; RFI = 0.91; GFI = 0.90; RMSEA = 0.078). The YFAS's 2.0 positive correlations with three DASS-21 subscales ranged from 0.30 to 0.39, and Food Craving Questionnaire-Trait, reduced (FCQ-T-r) ranged from 0.58 to 0.72. All correlations were statistically significant, indicating acceptable convergent validity (P < 0.01). CONCLUSION: The validity of the Persian questionnaire translation has been confirmed. Researchers and specialists can use this scale to diagnose food addiction for research or diagnostic purposes in Iranian society.


The term "food addiction" refers to the behavior of consuming highly palatable foods (such as salty, fatty, and sweet foods) in quantities beyond what is necessary to maintain a healthy diet. Some individuals may become addicted to food by consuming palatable and highly processed foods (e.g., fast food). There is growing scientific interest in food addiction. This study aims to examine the psychometric assessment of Persian translation of Yale Food Addiction Scale Version 2.0 (YFAS 2.0) In Iranian college students. Participants in the study included 451 Iranian college students who completed both questionnaires online. The results showed that the YFAS's 2.0, DASS-21, and FCQ-T-r had positive correlations indicating acceptable convergent validity. So the Persian translation YFAS 2.0 is suitable for measuring food addiction among Iranian college students, and it could be used in clinical and research settings.

9.
J Phys Chem B ; 126(41): 8300-8308, 2022 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-36197719

RESUMO

Mutual solubilities of hydrocarbon-CO2 systems are important in a broad range of applications. Experimental data and theoretical understanding of phase behavior of large hydrocarbon molecules and CO2 are limited. This is especially true in relation to the molecular structure of hydrocarbons when the carbon number exceeds 12. In this work, the continuous fractional component Gibbs ensemble Monte Carlo simulations are used to investigate mutual solubility of different alkane and CO2 systems and the molecular structure. We investigate the mutual solubility of n-decane, n-hexadecane, n-eicosane, and the corresponding structural isomers in the CO2-rich and hydrocarbon-rich phase. The focus will be solubility of the heavy normal alkanes and their structural isomers in CO2. The simulation results are verified by comparing the experimental data when measurements are available. The simulation of phase behavior of the n-decane-CO2 system agrees with the experiments. We also present simulation results of n-hexadecane-CO2 and n-eicosane-CO2 systems away from the critical region partly due to the finite size effect. We establish that solubility of the hydrocarbons in CO2 is improved by change of the molecular structure in heavier alkanes. The enhanced solubility is limited in decane isomers, but the isomers of hexadecane and eicosane show 2- to 3-time solubility enhancement. The molecular dynamics simulations suggest that the improvement is from a higher coordination number of CO2 for methyl (CH3) rather than for methylene (CH2) groups. This study sets the stage for molecular engineering and synthesis of hydrocarbons that are soluble in CO2 not only by considering functionality but also by changing the molecular structure. The solubility enhancement is the first step in viscosification of CO2 which broadens the use of CO2.

10.
J Chem Phys ; 157(4): 044701, 2022 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-35922357

RESUMO

The critical energy release rate (Gc) is a key parameter in numerical simulations of hydraulic fracturing, which may be affected by a fluid. Molecular dynamics (MD) simulations of minerals' tensile failure can be performed to gain insights into the mechanisms relevant to the critical energy release rate at the microscale. The methodology of calculating the critical energy release rate for solid-fluid systems is challenging. In this study, we conduct extensive MD simulations for solid-vacuum and solid-fluid systems. Typical components in shale and andesite, including quartz, muscovite, and kerogen, are selected in our investigation. The effect of H2O and CO2 on the critical energy release rate is analyzed. Fracture propagation and fluid invasion in fractures are also monitored. The results show that quartz and muscovite are brittle in H2O and CO2 and kerogen has very pronounced ductile behavior. H2O can reduce the critical energy release rate of quartz and muscovite slightly, but may increase that of kerogen. The effect of CO2 on quartz and muscovite is mild, while it reduces Gc of kerogen significantly. The implication is the creation of a much higher surface area in kerogen by CO2 than by H2O, which is in line with large-scale observations.

11.
iScience ; 25(5): 104266, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35521540

RESUMO

Viscosification of carbon dioxide by polymers can make large scale CO2 sequestration safe and efficient. We present solubility of branched hydrocarbon oligomers in CO2 and viscosification measurements at relevant subsurface conditions. Polymers of 1-decene (P1D) with about 20 repeating units are found to be effective in CO2 viscosification, increasing it by 6.5-fold at 1.8 wt% concentration at 308 K and 31 MPa. We reason that methyl groups and branching promote solubility and viscosification. Low molecular weight oligomers can have lower solubility in CO2 than higher molecular weight ones and the trend in solubility is non-monotonic at constant pressure and temperature. Analysis of solubility trend of P1D oligomers in CO2 advances our understanding of molecular structure and functionality and opens the path to engineering of oligomers effective in viscosification and widespread use of CO2.

13.
J Colloid Interface Sci ; 607(Pt 1): 125-133, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34500413

RESUMO

HYPOTHESIS: A large number of papers discuss merits and mechanisms of low salinity waterflooding. For each mechanism proposed, there are counter examples to invalidate the stated mechanism. The effect of wettability from low salinity water, which is predominantly stated in literature as the dominant mechanism, may not be valid. We introduce a direct correlation between oil-brine interfacial viscoelasticity and oil recovery from waterflooding. EXPERIMENTS: The oil recovery is investigated in carbonate rocks for three light crude oils, by injection of a wide range of aqueous phases, ranging from deionized water to very high salinity brine of 28 wt%, and low concentration of a non-ionic surfactant at 100 ppm. The oil-brine interfacial viscoelasticity is quantified and supplementary measurements of interfacial tension and wettability are performed. FINDINGS: In our experiments, oil recovery is higher from high salinity water injection than from low salinity water injection. A strong relationship is observed between interface elasticity and oil recovery for different concentrations of salt in the injected brine as well as for ultra-low concentration surfactant. An elastic oil-brine interface results in high oil recovery. The surfactant molecule we have selected prefers the oil-water interface despite high solubility in the oil phase and makes ultra-low concentration of 100 ppm in injection water very effective. Contrary to widespread assertions in the literature, we find no definitive correlation between oil recovery and wettability.


Assuntos
Salinidade , Tensoativos , Carbonatos , Tensão Superficial , Viscosidade
14.
J Phys Chem A ; 125(26): 5841-5848, 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34180665

RESUMO

Fluid-fluid interfacial free energy can be measured accurately and can also be calculated from molecular simulations. However, it is challenging to measure solid-fluid interfacial free energy directly. Accurate computation has not yet been advanced by molecular simulations. In this study, we derive working expressions for estimating solid-fluid interfacial free energy based on the free-energy perturbation method with consideration of solid deformation. A Lennard-Jones solid-fluid system is simulated. Our derivations indicate that the effect of solid deformation is pronounced on solid-fluid interfacial free energy, and the results may be significantly different from the conventional test area method. Our results reveal that the contribution of the solid deformation highly depends on the stress conditions in the solid, which can be either positive or negative. Adsorption of fluids onto the solid surface has a significant effect on interfacial free energy. In weak adsorption, the interfacial free energy is close to the solid-vacuum surface free energy. Strong adsorption results in a significant reduction in interfacial free energy.

15.
Langmuir ; 37(15): 4736-4743, 2021 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-33826353

RESUMO

Spontaneous emulsification near the oil-water interface and destabilization of water-in-oil emulsions in the bulk oil phase may affect the efficiency of improved oil recovery. In this study, we investigate the effect of a demulsifier surfactant on spontaneous emulsification near the oil-aqueous phase interface and in the bulk oil phase through imaging. The results show that pronounced spontaneous emulsions may form near the oil-aqueous phase interfaces. The mechanism of diffusion and stranding is believed to dominate spontaneous emulsification. A demulsifier surfactant, which has been used for demulsification of water-in-oil emulsions in the bulk oil phase, is found to enhance spontaneous emulsification near the oil-water interface. The diffusive flux of water through the interface can be enhanced if the demulsifier is added into the aqueous phase, in which the demulsifier may act as a carrier. It can generate a region of local supersaturation combined with hydrated asphaltenes and result in faster and stronger spontaneous emulsification. We also investigate the effect of a viscosifier polymer on emulsion formation. The polymer is used to improve sweep efficiency in oil displacement. In this work, we show that it can inhibit emulsification in the bulk oil phase, but its effect on spontaneous emulsification near the interface is not pronounced.

16.
Langmuir ; 36(41): 12160-12167, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32960615

RESUMO

Injection of sea water is the most common practice to displace oil in porous media in subsurface formations. In numerous studies, conventional surfactants at concentrations in a range of one weight percent have been proposed to be added to the injected water to improve oil recovery. Surfactants accumulate at the oil-water interface and may reduce the interfacial tension by three orders of magnitude or more, resulting in higher oil recovery. Recently, we have proposed the addition of ultralow concentration of a non-ionic surfactant to the injected water to increase interface viscoelasticity as a new process. The increase in interface viscoelasticity increases oil recovery from porous media. This alternative approach requires only a concentration of 100 ppm (two orders less than the conventional improved oil recovery) and therefore is potentially a much more efficient process. In this work, we present a comprehensive report of the process in an intermediate-wet carbonate rock. There is very little adsorption of the functional molecules to the rock surface. Because the critical micelle concentration is low (around 30 ppm), most of the molecules move to the fluid-fluid interface to form molecular structures, which give rise to an increase in interface elasticity. We also demonstrate that interface elasticity has a non-monotonic behavior with the salt concentration of injected brine, and an optimum salinity exists for maximum oil recovery.

17.
J Chem Phys ; 151(2): 024202, 2019 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-31301727

RESUMO

We report the Fickian diffusion (D12), thermal diffusion (DT), and Soret (ST) coefficients of 4 binary mixtures of isobutylbenzene (IBB) and n-alkanes (n-hexane, n-octane, n-decane, and n-dodecane) at 298.15 K and atmospheric pressure. The concentration is varied in the whole range. The Optical Beam Deflection technique is used in the measurements. We first verify our measurements with published data. The concepts of molecular similarity and mobility are invoked to investigate D12 and DT dependency on molecular weight and concentration. Our analysis reveals a combined effect of molecular mobility and similarity dependency of DT on concentration and molecular weight of the n-alkanes. The mobility of individual molecules describes the D12 dependency on concentration and molecular weight of alkanes. The dependency of D12 on concentration weakens as the n-alkane molecular weight increases. DT increases with IBB concentration for nC6 and nC8 and decreases with IBB concentration for nC10 and nC12. In this work, we demonstrate that the temperature contrast factors can be accurately estimated without the use of an interferometer.

18.
Langmuir ; 35(12): 4263-4269, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30821470

RESUMO

High-concentration brines generally cause the wettability of petroleum fluid-brine-rock systems to become less water-wet (more oil-wet). The addition of alcohols to the brine, however, may produce an opposite effect. In this work, we investigate the synergic effects of a low concentration of 1-pentanol and brines on the wettability of petroleum fluid-brine-rock systems. The variables examined include the mineral type (mica, quartz, calcite), brine concentration (0-3 M), ion type (monovalent and divalent), crude oil (samples from sandstone and carbonate reservoirs), and 1-pentanol concentration (0.5 and 1 wt %). Adding 1 wt % 1-pentanol to the brine only slightly affects the wettability of a petroleum fluid on sandstone-like mineral surfaces (mica and quartz), whereas the effect is significant for carbonate-like mineral surfaces (calcite). A maximum reduction of 80° in contact angle (measured through the brine phase) is observed at 0.1 M NaCl and 0.5 wt % 1-pentanol. ζ-Potentials of both brine-petroleum fluid and brine-rock interfaces are found to be insensitive to the presence of 1-pentanol in the brine. Based on these observations, we propose that the accumulation of 1-pentanol in the thin brine film confined between the petroleum fluid and the rock surface results in a significant change of the wettability. Our finding may have various practical applications, one of which is the use of a low concentration of 1-pentanol for improving oil production.

19.
ACS Cent Sci ; 4(7): 820-831, 2018 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-30062110

RESUMO

Adsorption of functional molecules on the surface of hydrates is key in the understanding of hydrate inhibitors. We investigate the adsorption of a hydrocarbon chain, nonionic and ionic surfactants, and ions at the hydrate-aqueous interface. Our results suggest a strong connection between the water ordering around solutes in bulk and the affinity for the hydrates surface. We distinguish two types of water ordering around solutes: (i) hydrophobic hydration where water molecules form a hydrogen bond network similar to clathrate hydrates, and (ii) ionic hydration where water molecules align according to the polarity of an ionic group. The nonionic surfactant and the hydrocarbon chain induce hydrophobic hydration and are favorably adsorbed on the hydrate surface. Adsorption of ions and the ionic headgroups on the hydrate surface is not favorable because ionic hydration and the hydrogen bond structure of hydrates are incompatible. The nonionic surfactant is adsorbed by the headgroup and tail while adsorption of the ionic surfactants is not favorable through the head. Water ordering is analyzed using the hydrogen bond and tetrahedral density profiles as a function of the distance to the chemical groups. The adsorption of solutes is studied through the free energy profiles as a function of the distance to the hydrate surface. Salt lowers the melting temperature of hydrates, disrupts hydrophobic hydration, reduces the solubility of solutes in the aqueous solution, and increases the propensity of solutes to be adsorbed on hydrate surfaces. Our studies are performed by the unbiased and steered molecular dynamics simulations. The results are in line with experiments on the effect of salt and alkanes in hydrate antiagglomeration.

20.
J Occup Health Psychol ; 23(2): 278-288, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27991803

RESUMO

This study examined how 2 different ways of being mentally engaged with work-related issues during evenings (affective rumination and problem-solving pondering) cause changes in psychological well-being over a 1-year period. We conducted a 3-wave longitudinal study with a time lag of 6 months between each wave. At the first measurement moment, participants filled out a survey over 5 consecutive working days assessing work-related affective rumination and problem-solving pondering during evenings. Exhaustion and health complaints were assessed at the first measurement moment as well as after 6 and 12 months. The 3 waves of data obtained from a total of 123 participants with full-time and primarily mentally demanding jobs were analyzed using latent growth curve modeling (LGM). The results showed that affective rumination is a significant predictor of increase in exhaustion over time. Problem-solving pondering was not found to be a significant predictor of change in psychological well-being over time. These findings demonstrate that work-related rumination during evenings may lead to health problems over time depending on the type of rumination. It suggests that unlike affective rumination, problem-solving pondering during evenings has no influence on psychological well-being over time. (PsycINFO Database Record


Assuntos
Fadiga/psicologia , Nível de Saúde , Estresse Ocupacional/psicologia , Pensamento , Trabalho/psicologia , Adulto , Distribuição por Idade , Fadiga/epidemiologia , Feminino , Humanos , Irã (Geográfico)/epidemiologia , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Satisfação Pessoal , Resolução de Problemas , Distribuição por Sexo , Inquéritos e Questionários , Adulto Jovem
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