Each of twelve volunteers, at 2 week intervals, received 1 g of antipyrine, a test drug, and were exposed for 4 h either to toluene (375 mg/m3) or xylene (435 mg/m3) singly or in combination with ethanol (0.45 g/kg body wt. before the onset of exposure and 0.15 g/kg thrice every 1 h during exposure to maintain a steady level of ethanol in blood approximately 11 mmol/dm3). No significant differences were found in salivary antipyrine half-life (T1/2 approximately 12 h); and clearance (ClAP approximately 0.83 cm3/s) between control and groups exposed to solvents and/or ethanol. Nevertheless, a tendency to increase the metabolic rate of antipyrine in xylene-exposed group (T1/2 approximately 6.8 h; ClAP approximately 1.40 cm3/s) and counteraction of ethanol (T1/2 approximately 15 h; ClAP approximately 0.63 cm3/s) should be noted. The stimulation of lipid peroxidation in the serum as a biological effect of combined exposure to ethanol and toluene/xylene was observed. 相似文献
Visually impaired individuals often rely on assistive technologies such as white canes for independent navigation. Many electronic enhancements to the traditional white cane have been proposed. However, only a few of these proof-of-concept technologies have been tested with authentic users, as most studies rely on blindfolded non-visually impaired participants or no testing with participants at all. Experiments involving blind users are usually not contrasted with the traditional white cane. This study set out to compare an ultrasound-based electronic cane with a traditional white cane. Moreover, we also compared the performance of a group of visually impaired participants (N = 10) with a group of blindfolded participants without visual impairments (N = 31). The results show that walking speed with the electronic cane is significantly slower compared to the traditional white cane. Moreover, the results show that the performance of the participants without visual impairments is significantly slower than for the visually impaired participants. No significant differences in obstacle detection rates were observed across participant groups and device types for obstacles on the ground, while 79% of the hanging obstacles were detected by the electronic cane. The results of this study thus suggest that electronic canes present only one advantage over the traditional cane, namely in its ability to detect hanging obstacles, at least without prolonged practice. Next, blindfolded participants are insufficient substitutes for blind participants who are expert cane users. The implication of this study is that research into digital white cane enhancements should include blind participants. These participants should be followed over time in longitudinal experiments to document if practice will lead to improvements that surpass the performance achieved with traditional canes.
Normal mode solutions of certain classes of linear, spatially time-invariant, self-adjoint and nonself-adjoint differential operators, with inhomogéneous boundary conditions in a finite region of arbitrary shape, are obtained by the use of Green's extended identity [1] in conjunction with the eigenvalue problems associated with the differential operators. Thus, continuum field theories belonging to these classes of operators, which encompass arbitrary (a) material and geometrical parameters, (b) spatial and time-dependent boundary conditions, (c) initial conditions can be solved by this technique. This is illustrated by the determination of the transient response of an axisymmetric, finite, thick transversely isotropic elastic hollow cylinder under inhomogeneous boundary conditions of all types (both pure and mixed). It is also shown that the displacement (separation-of-variables, integral transforms) and acceleration (Mindlin-Goodman, Williams) methods currently used for solutions of dynamic problems can both be derived from Green's extended identity. 相似文献
Different emulsifying techniques were used to study the influence of water on the oxidative degradation of extra virgin olive
oil. The emulsions of water/extra virgin olive oil, oxidized with O2, UV radiation, and Air, were prepared by dispersing water under different conditions. Oil oxidation, monitored by measuring
the PV and polyphenolic content, was greater for emulsions obtained with low dispersing power. A linear model was used to
correlate the PV and the polyphenolic content with dispersing energy. An important result was that the dispersed water exerted
a positive antioxidant effect on the oil. 相似文献
The effect of emulsion structure on the susceptibility to oxidation of emulsified olive oils was tested. Olive oil samples
were emulsified by adding a certain quantity of water in different ways. The resulting water-in-oil emulsions were then oxidized
with UV light. The results revealed that the emulsion structure played a significant role in the oxidation process of emulsified
olive oils. A kinetic mechanism is discussed based on the PV determined experimentally. The susceptibility of water-emulsified
extra virgin olive oils to oxidation was quantified by means of a dimensionless parameter that displayed a characteristic
dependence on the specific surface area of the water dispersed phase. 相似文献
Tetrabutylammonium tetraphenylborate (TBATPB) and triacetin were added during extrusion to melt blends of polylactic acid (PLA) and polycarbonate bisphenol A (PC) through a reactive compatibilization approach in order to enhance the materials' mechanical properties and thermal resistance. Dynamic mechanical thermal analysis revealed a new peak attributable to the glass transition temperature (Tg) of the PLA-PC copolymer at a temperature lower than the Tg typical of PC and higher than the Tg of PLA. The results of tensile tests, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy, size exclusion chromatography, and NMR analysis for the compatibilized and uncompatibilized blends were, on the whole, in agreement with the formation of the PLA-PC copolymer due to the action of the TBATPB and triacetin during the short extrusion time. The mechanical behaviour, morphology, and thermal properties of the PLA/PC compatibilized blends were investigated as a function of composition, with the intention of broadening the utility of these biobased-blends. Finally, a general scheme for the reactions that occur during extrusion was proposed based on the experimental results. 相似文献
We found that many spontaneous human tumors exhibit increased levels of endocellular diacylglycerol (DAG) which is synthesized de novo as a byproduct of glycolysis. It has been shown that DAG mimics phorbol esters as a full tumor promoter in mouse skin carcinogenesis. A short term DAG treatment activates protein kinase C (PKC), while a long term "chronic" treatment down-regulates PKC. We show here that chronic treatment of human fibroblast with DAG induces p53 down-regulation and inhibition of p53 functional activity, and protection from UV-induced apoptosis. As PKC phosphorylation is necessary for p53 functional activity, we propose that chronic DAG treatment mimics the same event occurring in vivo for the effect of glycolysis in tumor progression. 相似文献