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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of various additives, electrolytes and non-electrolytes, on the cloud point of non-ionic surfactants has been studied. Additives which salt-out the polyoxyethylene chains of the surfactants cause decreased stability of oil-in-water emulsions by decreasing the true hydrophile-lipophile balance (HLB) of the surfactant; additives such as sodium iodide and propanol salt-in the non-ionic surfactants and result in an increase in the effective or true HLB of the system. The latter additives do not increase the hydration of the polyoxyethylene chains but their effect must be on the structure of water so that the heat of hydration of the chains is altered. Experiments with free films of the aqueous surfactant (Brij 96) show that thinning rates are markedly affected by the additives, but there is little effect on the equilibrium thickness of the films (ca 11 nm). Nonetheless the thickness at the transition from thick film to equilibrium black film decreases with increasing cloud point of the solution indicating increased stability. The importance of structure formation in the liquid film separating the emulsion globules was demonstrated.
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PMID:Emulsion stabilization by non-ionic surfactants: the relevance of surfactant cloud point. 23 85

This study defines gross, histopathologic, and radiologic changes associated with intervertebral disc degeneration in a spontaneously occurring form of the disease in aging sand rats (Psammomys obesus). Sand rats (male/female) fed lab chow supplemented with desert salt bush were sacrificed at periods of 3-30 months. Lateral thoracolumbar spine films were obtained. At sacrifice, spines were surgically exposed and gross findings were recorded; after fixation/decalcification, histopathologic studies were carried out using hematoxylin and eosin, and Safranin-O with fast green counterstain. Metabolic studies included correlations of pathologic and radiologic findings with blood glucose and insulin levels. Disc-space narrowing and subchondral endplate sclerosis increased radiologically with age, with more severe lower lumbar disc lesions. Ligamentous calcifications ventral to involved discs and caudal vertebrae were common. Disc thinning and anterior vertebral bony/cartilaginous spurs were more marked with age. Microscopy revealed loss of nucleus pulposus physaliform cells, chondrocyte replication, disc necrosis, and ossification. Hyperglycemia with and without hyperinsulinemia was common. No statistically significant differences in pathologic findings were noted, neither in diabetic versus nondiabetic nor in hyperinsulinemic animals. The sand rat is a model of disc degeneration; similarities with possible overlap with diffuse idiopathic skeletal hyperostosis syndrome were noted.
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PMID:Spondylosis in sand rats: a model of intervertebral disc degeneration and hyperostosis. 218 1

To study the effects of a single parenteral dose of indomethacin on gastric epithelial proliferation, we performed the following study. Male Wistar rats weighing about 200 g were divided into two groups and given single intraperitoneal injections of indomethacin 5 mg/kg, either suspended in 0.5% carboxymethyl cellulose sodium salt or vehicle alone, after an overnight fast. After 6 h, all rats were injected by tail vein with tritiated thymidine, 1 microCi/g body weight, to label proliferating cells and were killed 1 h later. Sections from fundic and antral mucosae were processed for light autoradiography. Parenteral indomethacin resulted in spotty erosions in fundic mucosa. Histologically, there was congestion with or without epithelial disruption. These areas were excluded in the proliferation measurements. There was a significant decrease not only in the number of labeled cells but also in the thickness of the proliferative zone with the thinning of the entire mucosal thickness in the fundic mucosa. None of the measurements in antral mucosa showed significant difference. These results showed that a single parenteral injection of indomethacin inhibits epithelial proliferation and decreases mucosal thickness in fundic, but not antral mucosa of the rat.
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PMID:Effects of single parenteral indomethacin injection in rat fundic and antral epithelial proliferation. 221 52

We have examined the collagens synthesized by cultures of normal human corneal stromal cells. Radioactively labeled products, accumulated in the culture medium during a 24-h labeling period, were treated with pepsin and analyzed by SDS-polyacrylamide gel electrophoresis. The cell layer collagen was characterized by 2.6 M and 4.4 M salt fractionation at neutral pH. CM-cellulose column chromatography, SDS-gel electrophoresis, and cyanogen bromide peptide mapping. Type I alpha 1 and alpha 2 chains were the predominant components in both the cell layer and the medium fractions of normal human stromal cultures; type III collagen was found mostly in the culture medium; and type V collagen was associated with the cell layer. Immunofluorescent techniques used to visualize collagen deposition in the cell layer confirmed the presence of these collagen types. Keratoconus is a disease characterized by thinning and scarring of the central cornea. Stromal cells grown from keratoconus corneas produced similar types of collagen (types I, III, and V) as normal human controls. Cells from keratoconus patients, however, contained more type V collagen in the cell layer than did normal cells. The difference was seen only in the 4.4 M salt precipitates. Since type V collagen is one component of cell surfaces, the primary defect in cultures from keratoconus corneas could involve cell membrane and cell surface components.
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PMID:Identification of collagens synthesized by cultures of normal human corneal and keratoconus stromal cells. 633 47

The viscoelastic properties of poly(ethylene oxide) (PEO) solution were investigated using the dynamic oscillatory testing technique. With this technique, the effect of PEO molecular weight (MW), concentration, composition of mixed solvent systems consisting of propylene glycol, glycerol formal, and water, and the effect of NaCl salt on the viscoelastic properties of PEO solution were determined. Dynamic moduli (G1, G2), magnitude of complex viscosity (magnitude of eta*), and loss tangent (tan delta) were examined over a frequency range of 10(-3)-2.5 Hz at 30 degrees C. The results indicated that low MW PEOs show liquidlike behavior while high elasticity is exhibited by high MW PEOs due to entanglement formation. The complex viscosity, magnitude of eta*, exhibits shear thinning (power-law) characteristics under oscillatory measurements. The relationship between steady shear and complex viscosities follows the Cox-Merz rule over the shear rate and frequency region studied. Both the storage (G1) and loss (G2) modulus increase drastically as the proportion of water in the mixed solvent system increases. Similarly, both G1 and G2 are found to increase while the tan delta decreases with increasing concentration of PEOs. The addition of up to 2% w/w NaCl in an aqueous solution of 10% w/w 2 million MW PEO has no observed detrimental effect on the viscoelastic behavior.
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PMID:Viscoelastic properties of poly(ethylene oxide) solution. 788 67

Semi-dilute (ca 2 g/dl) aqueous xanthan (mean molar mass ca 1 x 10(6) g/mol), when heated in the presence of 0.1 M NaCl to a temperature above the order<-->disorder transition temperature, forms highly viscoelastic solutions when returned to room temperature. The steady shear and dynamic rheological behaviour of these solutions discloses a weak gel structure, the viscosity of which is unusually sensitive to the rate of shear. In shear thinning behaviour these heat and salt treated xanthan solutions mimic the properties of the aqueous hyaluronic acid solutions widely used in viscosurgical techniques. The double stranded model of native xanthan is invoked to interpret the observed behaviour of heat and salt treated semi-dilute aqueous xanthan.
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PMID:Thermal treatment of semi-dilute aqueous xanthan solutions yields weak gels with properties resembling hyaluronic acid. 844 29

Coalescence of oil-in-water emulsion droplets in a simple shear flow produced by a Couette device is considered. A phase Doppler anemometer was used to measure the droplet size distribution as a function of time for shear rates ranging from 55 to 213 s-1 and for sodium chloride salt concentrations from 0.095 to 0.6 M. The initial droplet size distribution was log-normal. During the coalescence process, the size distribution was self-preserving in accordance with D. L. Swift and S. K. Friedlander's analysis [J. Colloid Sci. 19, 621 (1964)]. In the limiting case of negligible repulsive force due to the electric double layer, the calculated stability ratios, corrected for droplet polydispersity, agree well with the theoretical analyses of G. R. Zeichner and W. R. Schowalter [AIChE J. 23, 243 (1977)] and D. L. Feke and W. R. Schowalter [J. Fluid Mech. 133, 17 (1983)] for the case of solid particle aggregation. The good agreement between the stability ratios for the case of coalescence of droplets in the present study and those for aggregation of solid particles indicates that resistance to film deformation and thinning present in the case of coalescence is not important compared with the collision process. Copyright 1998 Academic Press. Copyright 1998Academic Press
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PMID:Self-Preservation of the Drop Size Distribution Function and Variation in the Stability Ratio for Rapid Coalescence of a Polydisperse Emulsion in a Simple Shear Field 946 44

The creaming and rheology of fine n-tetradecane oil-in-water emulsions at pH 6.8 containing the commercial protein sodium caseinate and the ionic surfactant sodium dodecyl sulfate (SDS) have been studied, and an overview diagram relating surfactant composition and creaming stability has been constructed. The presence of both SDS and sodium caseinate in an emulsion system increases the overall stability with respect to creaming. Excess SDS promotes destabilization through fast creaming; this can be attributed to depletion flocculation brought about by unadsorbed surfactant micelles. Addition of sodium caseinate was found to reduce this effect, even at relatively high SDS concentrations. The behavior of the caseinate + SDS emulsions is thus different from the behavior of the previously reported caseinate + Tween 20 systems, where the combination of the two surface-active agents was found to reduce the emulsion stability, as indicated by fast creaming and shear-thinning rheology. Addition of sodium chloride was found to increase the extent of non-Newtonian behavior and to enhance the degree of creaming for SDS-containing emulsions. Increased caseinate levels in these systems seem to offer some stabilization through reduction of the shear-thinning character and improvement in creaming stability. These phenomena can be explained in terms of a considerable amount of SDS binding to the protein, which reduces the amount of SDS available to promote protein displacement and depletion flocculation. In contrast to the SDS systems, the properties of equivalent emulsions containing caseinate + nonionic surfactant Tween 20 are relatively insensitive to salt content. Copyright 2000 Academic Press.
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PMID:Creaming and Rheology of Oil-in-Water Emulsions Containing Sodium Dodecyl Sulfate and Sodium Caseinate. 1070 4

The thinning behavior of liquid films between free bubbles and silica is investigated using the interferometric technique. Stable films were obtained at higher salt concentrations compared to previous studies because of the improved cleaning procedure. In contrast to the captive bubble technique used in the past, the free bubble method employed more closely approximates such processes as flotation. The results obtained for aqueous films at low and high ionic strengths are in better agreement with theoretical predictions than those in previous studies. Copyright 2000 Academic Press.
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PMID:Investigation of Thin Aqueous Films on Silica Using a Modified Interferometric Technique. 1076 67

The aim of this study was to estimate the influence of biotic and abiotic factors on Suaeda maritima reproduction on a salt marsh. Individuals of Suaeda maritima were submitted in natural conditions to four series of densities (100, 1,000, 4,000 and 8,000 plants/m2). When density increases, individuals tend to be less or non-branched, while individual biomass decreases. Consequently, individual seed production decreases as density increases. Despite morphological modifications, Suaeda maritima present density-dependent mortality. For a unit area, total biomass and seed production are higher at intermediate density (1,000 plants/m2). Environmental factors could interfere with self-thinning. They seem to limit the effect of competition on mortality and to have an influence on individual and total seed production. This experiment stressed the importance of a biotic factor such as intra-specific competition, which occurs at the same time as abiotic factors, in Suaeda maritima dynamics in the field.
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PMID:[Influence of biotic and abiotic factors on the morphology and reproduction of Suaeda maritima on a salt marsh]. 1109 6


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