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Increased Viscosity (increased + viscosity)

Distribution by Scientific Domains
Medical Sciences33%

Selected Abstracts

Effect of trefoil factors on the viscoelastic properties of mucus gels

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 7 2002
L. Thim
Abstract Background Trefoil peptides (TFFs) are expressed and secreted in a tissue-specific manner in the gastrointestinal tract. Evidence of coexpression of trefoil peptides and mucins has been demonstrated in most mucus-producing cells in the gastrointestinal tract. The expression of trefoil peptides is up-regulated in gastric ulceration and colitis. It is believed that TFF peptides interact with mucin to increase viscosity but this has never been confirmed. The aims of the present study were to elucidate the direct effect of trefoil peptides on mucus gel formation. Materials and methods The viscosity of mucin solutions was measured by means of a rotational rheometer after adding three mammalian trefoil peptides: TFF1, TFF2, and TFF3. Results Adding TFF2 (0·3%) to the mucin solutions (8%) resulted in more than a factor 10 increase in viscosity and elasticity, and the mucin solution was transformed into a gel-like structure with serpentine-like complexes between the mucin and TFF2. The dimer form of TFF3 also increased viscosity but resulted in a spider's web-like structure. The monomer forms of TFF1 and TFF3 had very little effect on the viscosity and elasticity of the mucin solutions. Conclusions The addition of TFF2 to mucin solutions results in significantly increased viscosity and elasticity, under which the mucin solutions are transformed into a gel-like state. The ability of some trefoil peptides to catalyse the formation of stable mucin complexes may be one of the ways by which these peptides exert their protective and healing functions. [source]

Analytic Determination of Hydrocarbon Transmissivity from Baildown Tests

GROUND WATER, Issue 1 2000
David Huntley
Hydrocarbon baildown tests involve the rapid removal of floating hydrocarbon from an observation or production well, followed by monitoring the rate of recovery of both the oil/air and oil/water interfaces. This test has been used erroneously for several years to calculate the "true thickness" of hydrocarbon in the adjacent formation. More recent analysis of hydrocarbon distribution by Farr et al. (1990), Lenhard and Parker (1990), Huntley et al. (1994), and others have shown that, under vertical equilibrium conditions, there is no thickness exaggeration of hydrocarbon in a monitoring well, though there is a significant volume exaggeration. This body of work can be used to demonstrate that the calculation of a "true hydrocarbon thickness" using a baildown test has no basis in theory. The same body of work, however, also demonstrates that hydrocarbon saturations are typically much less than one, and are often below 0.5. Because the relative permeability decreases as hydrocarbon saturation decreases, the effective conductivity and mobility of the hydrocarbon is much less than that of water, even ignoring the effects of increased viscosity and decreased density. It is important to evaluate this decreased mobility of hydrocarbon due to partial pore saturation, as it has substantial impacts on both risk and remediation. This paper presents two analytic approaches to the analysis of hydrocarbon baildown test results to determine hydrocarbon transmissivity. The first approach is based on a modification of the Bouwer and Rice (1976) analysis of slug withdrawal test data. The second approach is based on a modification of Jacob and Lohman's (1952) constant drawdown,variable discharge aquifer test approach. The first approach can be applied only when the effective water transmissivity across the screened interval to water is much greater than the effective hydrocarbon transmissivity. When this condition is met, the two approaches give effectively identical results. [source]

Skin moisturization by hydrogenated polyisobutene,Quantitative and visual evaluation

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2010
N. Dayan
J. Cosmet. Sci., 60, 15,24 (January/February 2009) Synopsis Hydrogenated polyisobutene (HP) is used in topically applied cosmetic/personal care formulations as an emollient that leaves a pleasing skin feel when applied, and rubbed in after application. This effect, although distinguishable to the user, is difficult to define and quantify. Recognizing that some of the physical properties of HP such as film formation and wear resistance may contribute, in certain mechanisms, to skin moisturization, we designed a short-term pilot study to follow changes in skin moisturization. HP's incorporation into an o/w emulsion at 8% yielded increased viscosity and reduced emulsion droplet size as compared to the emollient ester CCT (capric/caprylic triglyceride) or a control formulation. Quantitative data indicate that application of the o/w emulsion formulation containing either HP or CCT significantly elevated skin moisture content and thus reduced transepidermal water loss (TEWL) by a maximal ,33% against the control formulation within 3 h and maintained this up to 6 h. Visual observation of skin treated with the HP-containing formulation showed fine texture and clear contrast as compared to the control or the CCT formulation, confirming this effect. As a result of increased hydration, skin conductivity, as measured in terms of corneometer values, was also elevated significantly by about tenfold as early as 20 min after HP or CCT application and was maintained throughout the test period. Throughout the test period the HP formulation was 5,10% more effective than the CCT formulation both in reduction of TEWL as well as in increased skin conductivity. Thus, compared to the emollient ester (CCT), HP showed a unique capability for long-lasting effect in retaining moisture and improving skin texture. [source]

Nanosized-Silica-Reinforced Holographic Polymer-Dispersed Liquid Crystals

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2006
Eun Hee Kim
Abstract Summary: Nanosized silicas added to holographic polymer-dispersed liquid crystals (HPDLC) provide the resin phase with increased elasticity, dimensional stability, and the high diffraction efficiency of the gratings. On the other hand, nucleation and growth of periodic modulation are delayed, especially with small-sized silica because of the increased viscosity of the resin mixture. Effects of the LC/resin composition and cell gap on the diffraction efficiency have also been studied. AFM image of silica added HPDLC. [source]

A new role for bicarbonate secretion in cervico-uterine mucus release

THE JOURNAL OF PHYSIOLOGY, Issue 13 2010
Ruth W. Muchekehu
Cervical mucus thinning and release during the female reproductive cycle is thought to rely mainly on fluid secretion. However, we now find that mucus released from the murine reproductive tract critically depends upon concurrent bicarbonate (HCO3,) secretion. Prostaglandin E2 (PGE2)- and carbachol-stimulated mucus release was severely inhibited in the absence of serosal HCO3,, HCO3, transport, or functional cystic fibrosis transmembrane conductance regulator (CFTR). In contrast to mucus release, PGE2 - and carbachol-stimulated fluid secretion was not dependent on bicarbonate or on CFTR, but was completely blocked by niflumic acid. We found stimulated mucus release was severely impaired in the cystic fibrosis ,F508 reproductive tract, even though stimulated fluid secretion was preserved. Thus, CFTR mutations and/or poor bicarbonate secretion may be associated with reduced female fertility associated with abnormal mucus and specifically, may account for the increased viscosity and lack of cyclical changes in cervical mucus long noted in women with cystic fibrosis. [source]

Drag enhancement of aqueous electrolyte solutions in turbulent pipe flow

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2007
E. Benard
Abstract Experimental measurements have indicated that drag enhancement occurs when aqueous electrolyte solutions are flowing in the turbulent regime. The primary electroviscous effect due to the distortion by the shear field of the electrical double layer surrounding the ions in solution is invoked to explain the drag enhancement. Calculations using the Booth model for symmetrical one-to-one electrolytes enabled the increased viscosity in the turbulent regime to be calculated. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd. [source]