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

The peripheral nerve biopsy specimens of 4 cases of toxic polyneruopathies induced by exposure to leather cement in shoe industries were studied. Analysis of the cements used in the manufacturing process proved them to contain n-hexane as a volatile substance. Light- and electron-microscopic examination of nerve biopsies showed segmental swelling of axons due to the accumulation of packed filaments and thinning of the overlying myelin sheath. Neither active nerve fibre degeneration nor regeneration were frequently seen. It has been suggested that features of so-called giant axonal neuropathy are the most common pattern of peripheral nerve degeneration in chronic n-hexane intoxication.
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PMID:Toxic polyneuropathies in Italy due to leather cement poisoning in shoe industries. A light- and electron-microscopic study. 19 69

Although industrial exposure to n-hexane is known to cause neuropathy, it is less well recognized that inhalation of n-hexane present in the vapors of some commercial contact cements is also neurotoxic to peripheral nerves. A young man with a long history of addictive glue-sniffing developed severe distal symmetrical polyneuropathy several months after switching to a cement containing n-hexane and gradually improved several months after switching to another cement containing no n-hexane. Fascicular biopsy of radial cutaneous nerve showed striking segmental distention of axons by neurofilamentous masses with secondary thinning of myelin sheath, paranodal myelin retraction, and widening velocities were correspondingly slow. We conclude that n-hexane used as a solvent in some contact cements may be neurotoxic when inhaled to excess and, further, that the neuropathy has characteristic electrophysiological and pathological features.
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PMID:Glue-sniffing neuropathy. 111 59

A new method is presented for the qualitative and quantitative estimation of trace amounts (up to 0.15 ppm) of benzene in crude as well as refined vegetable oils obtained by extraction with food grade hexane (FGH), and in the oil seed cakes left after extraction. The method involves the selection of two solvents; cyclohexanol, for thinning of viscous vegetable oil, and heptane, for azeotroping out trace benzene as a concentrate from the resulting mixture. Benzene is then estimated in the resulting azeotrope either by UV spectroscopy or by GC-MS subject to availability and cost effectiveness of the latter. Repeatability and reproducibility of the method is within 1-3% error. This method is suitable for estimating benzene in vegetable oils and oil seed cakes.
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PMID:Estimation of trace amounts of benzene in solvent-extracted vegetable oils and oil seed cakes. 1106 41

Many non-aqueous phase liquids (NAPLs) are expected to spread at the air-water interface, particularly under non-equilibrium conditions. In the vadose zone, this spreading should increase the surface area for mass transfer and the efficiency of volatile NAPL recovery by soil vapor extraction (SVE). Observations of spreading on water wet surfaces led to a conceptual model of oil spreading vertically above a NAPL pool in the vadose zone. Analysis of this model predicts that spreading can enhance the SVE contaminant recovery compared to conditions where the liquid does not spread. Experiments were conducted with spreading volatile oils hexane and heptane in wet porous media and capillary tubes, where spreading was observed at the scale of centimeters. Within porous medium columns up to a meter in height containing stagnant gas, spreading was less than ten centimeters and did not contribute significantly to hexane volatilization. Water film thinning and oil film pinning may have prevented significant oil film spreading, and thus did not enhance SVE at the scale of a meter. The experiments performed indicate that volatile oil spreading at the field scale is unlikely to contribute significantly to the efficiency of SVE.
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PMID:Non-aqueous phase liquid spreading during soil vapor extraction. 1473 43

A model is developed to study diffusive mass transfer of hydrocarbon vapor through a flexible foam blanket. The model accounts for the diffusion of hydrocarbon vapor through gas-phase and liquid lamellae, the combined gravity and capillary drainage from the plateau border, the thinning of foam lamellae caused by the forces of capillary suction, London-van der Waals attraction, and electrostatic double-layer repulsion, and foam collapse. Uniform bubble size is assumed, and hence, interbubble gas diffusion arising out of variation in bubble sizes alone is not incorporated into the model. A high-stability aqueous foam formulation that remains stable in the presence of oil (hexane) at foam-oil contact was developed using surfactants, stabilizers, and viscosifiers. Emission of hexane vapor through the foam was measured. The model predicts that the initially taller foam columns collapse faster. Their mass-transfer resistance is higher before the onset of collapse but not very different from that of the shorter foam columns at long times. If the solubility and diffusivity of the hexane gas in the foam liquid are unaffected, the foams with higher viscosities persist longer and provide greater diffusive mass-transfer resistance. Foam bubble size does not significantly impact the mass-transfer resistance of the foam column before the onset of foam collapse. However, the foams with smaller bubbles collapse earlier, and their ability to act as a mass-transfer barrier to the diffusing hydrocarbon vapor diminishes rapidly. The experimental results compared reasonably with the model for varying initial foam heights and bubble sizes.
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PMID:Mass transfer of volatile organic carbons through aqueous foams. 1508 1

A transient molecular dynamics (TMD) method for obtaining fluid viscosity is extended to multisite, force-field models of both nonpolar and polar liquids. The method overlays a sinusoidal velocity profile over the peculiar particle velocities and then records the transient decay of the velocity profile. The viscosity is obtained by regression of the solution of the momentum equation with an appropriate constitutive equation and initial and boundary conditions corresponding to those used in the simulation. The transient velocity decays observed appeared to include both relaxation and retardation effects. The Jeffreys viscoelastic model was found to model accurately the transient responses obtained for multisite models for n-butane, isobutane, n-hexane, water, methanol, and 1-hexanol. TMD viscosities obtained for saturated liquids over a wide range of densities agreed well for the polar fluids, both with nonequilibrium molecular dynamics (NEMD) results using the same force-field models and with correlations based on experimental data. Viscosities obtained for the nonpolar fluids agreed well with the experimental and NEMD results at low to moderate densities, but underpredicted experimental values at higher densities where shear-thinning effects and viscous heating may impact the TMD simulations.
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PMID:Transient molecular dynamics simulations of liquid viscosity for nonpolar and polar fluids. 2124 Nov 39

Retinal ganglion cells (RGCs) death caused by oxidative stress is a common risk factor for glaucoma. In the present study, 8-hydroxycalamenene was isolated from the hexane fraction of Reynoutria elliptica. We showed that 8-hydroxycalamenene attenuated the cell death of transformed RGC-5 cells. This compound also produced a dose-dependent decrease in the expression of apoptotic proteins (cleaved PARP and caspase-3) induced by l-buthionine-(S,R)-sulfoximine (BSO) plus glutamate and stimulated glutathione and glutathione S-transferase activity. Moreover, the addition of 8-hydroxycalamenene to cell cultures restored the reduced mitochondrial membrane potential resulting from glutamate/BSO treatment. The presence of N-methyl-d-aspartate in the retina of rats affected the thickness of the inner plexiform layer (IPL) and increased the number of TUNEL-positive RGCs. However, 8-hydroxycalamenene protected against thinning of the IPL and reduced TUNEL-positive cells in the ganglion cell layer. Thus, 8-hydroxycalamenene isolated from R. elliptica exerts neuroprotective effects both in vitro and in vivo.
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PMID:8-Hydroxycalamenene isolated from the rhizomes of Reynoutria elliptica exerts neuroprotective effects both in vitro and in vivo. 2303 15

The rheological, physicochemical properties, emulsification and stability of exopolysaccharides (EPSs) from four rhizobia isolates (LBMP-C01, LBMP-C02, LBMP-C03 and LBMP-C04) were studied. The EPS yields of isolates under these experimental conditions were in the range of 1.5-6.63gL(-1). The LBMP-C04 isolate, which presented the highest EPS production (6.63gL(-1)), was isolated from Arachis pintoi and was identified as a Rhizobium sp. strain that could be explored as a possible potential source for the production of extracellular heteropolysaccharides. All polymers showed a pseudoplastic non-Newtonian fluid behavior or shear thinning property in aqueous solutions. Among the four EPS tested against hydrocarbons, EPS LBMP-C01 was found to be more effective against hexane, olive and soybean oils (89.94%, 82.75% and 81.15%, respectively). Importantly, we found that changes in pH (2-11) and salinity (0-30%) influenced the emulsification of diesel oil by the EPSs. EPSLBMP-C04 presented optimal emulsification capacity at pH 10 (E24=53%) and 30% salinity (E24=27%). These findings contribute to the understanding of the influence of the chemical composition, physical properties and biotechnology applications of rhizobial EPS solutions their bioemulsifying properties.
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PMID:Chemical and rheological properties of exopolysaccharides produced by four isolates of rhizobia. 2623 81

Equilibrium and non-equilibrium molecular dynamics simulations are performed on liquid hexane in order to clarify the origin of the Cox-Merz rule of liquids composed of chain-like molecules. The relation between the frequency-dependent complex shear viscosity and the shear-rate dependent nonlinear viscosity follows the Cox-Merz rule as expected. The slowest viscoelastic relaxation mode is explained by the translation-orientation coupling mechanism, and the saturation of the shear-induced orientational order is observed in the non-equilibrium simulation at the onset of the shear thinning. The origin of the Cox-Merz rule is discussed in terms of the translation-orientation coupling.
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PMID:Translation-orientation coupling and Cox-Merz rule of liquid hexane. 3050 Dec 58