Novel Kinetic Effects in Vkcoelasttc Surfactant Solutions Under Shear

1994 ◽  
Vol 376 ◽  
Author(s):  
P.D. Butler ◽  
L.J. Magid ◽  
P.J. Kreke ◽  
J.B. Hayter ◽  
W.A. Hamilton ◽  
...  
Keyword(s):  
Micellar Solutions ◽  
Micellar Systems ◽  
Surfactant Solutions ◽  
Order Of Magnitude ◽  
Kinetic Effects ◽  
The Individual ◽  
Two Stages ◽  
Aqueous Micellar Solutions ◽  
Transient Alignment ◽  
Threadlike Micelles

ABSTRACTUsing small-angle neutron scattering (SANS), we have investigated the transient alignment and relaxation under Couette shear of viscoelastic aqueous micellar solutions of cetyltrimethylarmmonium 3,5-dichlorobenzoate (CTA3,5C1) and CTA3,5C1/CTAB mixtures at concentrations well above ф* (but below 1.0 wt. %). Time constants of the order of ten's of minutes are reported for alignment and relaxation, orders of magnitude slower than any previously observed in similar micellar systems. The collective properties of the network of entangled, threadlike micelles, rather than the individual micellar segments, dominate the alignment and relaxation behavior. At low micellar surface charge density (σ) (e.g., in pure CTA3,5C1), the first observation of alignment proceeding in two stages has been made. Increasing a decreases by an order of magnitude the shear rate required to reach full alignment and provides a comparable decrease in the rate constant for relaxation after cessation of shear.

scholarly journals Statistical Uncertainty of DNS in Geometries without Homogeneous Directions

2021 ◽  
Vol 11 (4) ◽  
pp. 1399
Author(s):  
Jure Oder ◽  
Cédric Flageul ◽  
Iztok Tiselj
Keyword(s):  
Channel Flow ◽  
A Priori ◽  
Time Integration ◽  
Navier Stokes ◽  
Statistical Uncertainty ◽  
Time Step ◽  
Order Of Magnitude ◽  
Averaging Time ◽  
The Individual ◽  
Time Required

In this paper, we present uncertainties of statistical quantities of direct numerical simulations (DNS) with small numerical errors. The uncertainties are analysed for channel flow and a flow separation case in a confined backward facing step (BFS) geometry. The infinite channel flow case has two homogeneous directions and this is usually exploited to speed-up the convergence of the results. As we show, such a procedure reduces statistical uncertainties of the results by up to an order of magnitude. This effect is strongest in the near wall regions. In the case of flow over a confined BFS, there are no such directions and thus very long integration times are required. The individual statistical quantities converge with the square root of time integration so, in order to improve the uncertainty by a factor of two, the simulation has to be prolonged by a factor of four. We provide an estimator that can be used to evaluate a priori the DNS relative statistical uncertainties from results obtained with a Reynolds Averaged Navier Stokes simulation. In the DNS, the estimator can be used to predict the averaging time and with it the simulation time required to achieve a certain relative statistical uncertainty of results. For accurate evaluation of averages and their uncertainties, it is not required to use every time step of the DNS. We observe that statistical uncertainty of the results is uninfluenced by reducing the number of samples to the point where the period between two consecutive samples measured in Courant–Friedrichss–Levy (CFL) condition units is below one. Nevertheless, crossing this limit, the estimates of uncertainties start to exhibit significant growth.

Validation of the Chinese Version of the Multidimensional Workaholism Scale

2021 ◽  
pp. 106907272199427
Author(s):  
Yan Xu ◽  
Chaoping Li
Keyword(s):  
Factor Analysis ◽  
Reliability And Validity ◽  
Well Being ◽  
Chinese Version ◽  
Full Time ◽  
Work Family Conflict ◽  
Working Adults ◽  
Work Family ◽  
The Individual ◽  
Two Stages

The aim of this study was to translate the Multidimensional Workaholism Scale (MWS) into Chinese and then test its reliability and validity among full-time Chinese employees in two stages. In Study 1 ( N = 220), the MWS was translated and exploratory factor analysis was conducted resulting in a four-factor solution consistent with the original MWS: motivational, cognitive, emotional, and behavioral. In Study 2 ( N = 425), confirmatory factor analysis showed that a four-factor, bifactor model was the best fit for the data. Configural, metric, and scalar invariance models were tested which demonstrated that the Chinese version of the MWS did not differ across gender, age, and job position groups. Finally, workaholism and engagement were related and distinct from one another, and they correlated with emotional exhaustion, work-family conflict and life well-being uniquely. This study indicated that the Chinese version of the MWS is a valid and reliable tool for Chinese employees, and this has important practical implications for the individual health and career development of Chinese working adults.

Fluorescence of anthracene in frozen aqueous micellar solutions

1990 ◽  
Vol 52 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Thomas Wolff ◽  
Susanne Weber ◽  
Günther Von Bünau
Keyword(s):  
Micellar Solutions ◽  
Aqueous Micellar Solutions

Comparison of the Photochemical Behaviors of α-Tocopherol and its Acetate in Organic and Aqueous Micellar Solutions

2011 ◽  
Vol 115 (29) ◽  
pp. 8242-8247 ◽  
Author(s):  
Ye Zhang ◽  
Y. A. Yousef ◽  
Heng Li ◽  
T. B. Melø ◽  
K. Razi Naqvi
Keyword(s):  
Micellar Solutions ◽  
Aqueous Micellar Solutions

Solubilization in Aqueous Micellar Solutions Studied by NMR-Methods

1982 ◽  
pp. 907-919 ◽  
Author(s):  
Jan Christer Eriksson ◽  
Ulf Henriksson ◽  
Tomas Klason ◽  
Lars Ödberg
Keyword(s):  
Micellar Solutions ◽  
Nmr Methods ◽  
Aqueous Micellar Solutions

scholarly journals Фотофизические процессы в молекулах галогенпроизводных флуоресцеина в анионных обратных мицеллах

2020 ◽  
Vol 128 (12) ◽  
pp. 1842
Author(s):  
О.И. Волкова ◽  
А.А. Кулешова ◽  
Б.Н. Корватовский ◽  
А.М. Салецкий
Keyword(s):  
Reverse Micelles ◽  
Heavy Atom ◽  
Rotational Correlation Time ◽  
Dye Molecules ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Micellar Systems ◽  
Aqueous Micellar Solutions ◽  
Derivatives Of ◽  
Rotational Correlation

Studies of photophysical processes in aqueous micellar solutions of halogen derivatives of fluorescein: Eosin( E), Erythrosin (ER) and Bengal Rose (BR) by methods of dynamic light scattering, stationary and time-resolved fluorescence spectroscopy were carried out. It was found that the introduction of dye molecules into reverse AOT micelles causes an increase in their hydrodynamic radii Rh. The time-resolved fluorescence of the studied dye molecules in reverse micelles was measured. A decrease in the average time of the excited state with an increase in Rh for E, ER, and BR was found, which is associated with an increase in the mobility of water molecules and a decrease in the effect of geometric restriction of dye molecules. The degrees of anisotropy of the fluorescence r of dye molecules in reverse micelles were measured. It was shown that in micellar systems r is greater than in aqueous solutions and decreases with increasing Rh. The rotational correlation time for the studied dye molecules in micellar systems is determined, which decreases for all the studied dyes with an increase in Rh, indicating a decrease in the microviscosity of the confined aqueous medium inside the micelle. In this case , i.e., the value of the time of the rotational correlation is affected by the "heavy atom effect".

scholarly journals Mineral composition and formation conditions of the Inkur tungsten deposit ores (Dzhidinsky ore field, South-Western Transbaikalia)

2020 ◽  
Vol 43 (3) ◽  
pp. 290-306
Author(s):  
L. B. Damdinova ◽  
B. B. Damdinov
Keyword(s):  
Mineral Composition ◽  
Tungsten Deposit ◽  
Homogeneous Solutions ◽  
Western Transbaikalia ◽  
Low Salinity ◽  
Mineral Associations ◽  
Formation Conditions ◽  
The Individual ◽  
Two Stages ◽  
Petrographic Description

The aim of the study is to clarify the mineral composition and determine the conditions of the formation of the quartz-hubnerite veins of the Inkur stockwork tungsten deposit (the Dzhidinsky ore field, South-Western Transbaikalia). The research methods include a mineralogical and petrographic description of the ore quartz-hubnerite veins; an electron microprobe analysis of the mineral associations; thermometry, cryometry, and Raman spectroscopy of the individual fluid inclusions in quartz, fluorite, hubnerite, and muscovite. The mineralogical and petrographic studies has made it possible to clarify the mineral composition of the Inkur deposit ores and determine the mineral paragenesis formation sequence. The fluid inclusion studies have established that the ore deposition was occurring in the relatively low-salinity (~5.7–14.6 wt. % eq. NaCl) homogeneous solutions due to a decrease of the temperature. The study of the salt composition of the solutions has identified Ca chloride as a prevailing component, with NaCl, KCl, and MgCl as admixtures. CO2 and N2 have been identified in the gas phase of inclusions. Two stages of mineral formation have been defined: high-temperature (≥300 °С) and low-temperature (≥2.00–300 °С). The conducted studies allow qualitative estimation of the chemical composition of the ore-forming solutions. It has been established that one of the main factors of the hubnerite deposition is a temperature factor.

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