Neurotoxicity induced by exposure to toluene. An electrophysiologic study

The object of the present study was to evaluate, with the aid of electrophysiologic techniques, the alterations induced in the auditory nervous system by exposure to toluene in a group of rotogravure workers. From 300 workers who were apparently in good health but were professionally exposed to toluene, we selected a sample of 40 workers of normal hearing ability. They were examined with an adaptation test studied by the brainstem auditory evoked potential technique with 11 and 90 stimulus repetitions a second. The results were compared with those in a group of workers of the same age but not professionally exposed to solvents. Our study demonstrates that exposure to toluene is able to induce a statistically significant alteration in the electric responses with both 11 and 90 stimuli repetitions. This alteration can be explained as a toluene exposure-induced modification, of physiologic stimulus conduction mechanisms, even in the absence of any clinical sign of neuropathy. Furthermore, such a modification could be observed in the electric responses of the entire auditory system, from peripheral receptors to brainstem nuclei.     

Chemical,antioxidant, functional and thermal properties of rice bran proteins after yeast and natural fermentations

The paper focuses on the chemical, antioxidant, functional and thermal properties of rice bran proteins after yeast, natural fermentations and unfermented rice bran. Protein content of yeast‐fermented rice bran protein concentrate (YFRBPC), naturally fermented rice bran protein concentrate (NFRBPC) and unfermented rice protein concentrate (UFRBPC) were 72.50%, 68.92% and 65.73%, respectively, while ash content were 4.72%, 4.61% and 3.04%, respectively. The total amino acids of YFRBPC, NFRBPC and UFRBPC were 123.16, 118.45 and 99.39, respectively. DPPH radical inhibition of YFRBPC, NFRBPC and UFRBPC were 58.62%, 55.29% and 47.14%, respectively, while ferric reducing ability power were 0.73, 0.58 and 0.41 mmol TE per gram, respectively. The highest foam capacity of UFRBPC (57.56%), NFRBPC (64.15%) and YFRBPC (76.00%) was observed at pH 9.0. YFRBPC and NFRBPC were lighter in colour than UFRBPC. YFRBPC had higher denaturation temperature and enthalpy value than NFRBPC and UFRBPC. The β‐sheets structures were more in YFRBPC and NFRBPC than UNFBPC.     

Effect of ecofriendly grapefruit peel extract on PVC thin films photostabilizing tested under harmful weathering conditions

Exposure to ultraviolet radiation triggers a photooxidative deterioration mechanism in plastics, resulting in bond breakage, release of volatile substances, overall weight reduction, generation of free radicals, and loose crosslinking. The aim of this study was to obtain a plant extract with appropriate concentration and use it to protect polyvinyl chloride (PVC) from photodegradation. PVC films containing different concentrations of naringin that were already extracted and TINUVIN 622 as a commercial stabilizer were investigated in this paper. UV light was used to irradiate PVC films for 300 h to test the photostability. After radiation, infrared spectra, weight loss, molecular weight reduction, and surface morphology examination for PVC films were studied. In comparison to blank film, the photodegradation of PVC films was significantly reduced by the naringin and TINUVIN 622 photostabilizers. The role of photostabilizers includes deactivating excited states (as quenchers), functioning as effective light filters (pigments and absorbers), scavenging radicals, and decomposing hydroperoxides.     

The use of gas chemistry to evaluate boiling processes and initial steam fractions in geothermal reservoirs with an example from the olkaria field, Kenya

A method has been developed to evaluate boiling processes in the producing aquifer of “high-enthalpy” geothermal wells using data on the concentrations of CO₂, H₂S and H₂ in steam discharged. The extent to which water and steam are separated in the producing aquifer is evaluated as well as the amount of enhanced evaporation due to heat flow from the rock to the boiling water. Further, the initial steam fraction in the reservoir fluid is calculated. Results are presented for the Olkaria geothermal field, Kenya, to demonstrate the use of our method. They show that the initial steam fraction in the reservoir is very small: up to 0.25% of the mass, or about 10% by volume. Segregation of water and steam in the producing aquifers is rather extensive for some of the wells. Thus, water which has boiled and yielded steam into wells amounts to more than two times the mass of the fluid discharged from the well. The larger part of the exploited steam ( ) is generated by flow of heat from the rock to the boiling water.     

Materielles Recycling thermoplastischer Kunststoffabfälle

Material Recycling of Plastics Waste. The recycling of plastics waste comprises of two main steps, viz. waste preparation and melt processing. Depending on the quality of the waste input and the desired product, the various recycling processes differ considerably in these two steps. For mixed and contaminated plastics wastes, processes are available which, with minimum preparation, process the melt into thick-walled products. Better defined plastics wastes on the other hand are treated with greater investment in preparation and are generally processed with extrusion into granules for normal plastic processes. Preparation includes shredding, washing and drying, sorting, and agglomeration.     

Study of the elution of fluconazole from a self-polymerizing acrylic resin and its activity against resistant <Emphasis Type="Italic">Candida albicans</Emphasis>

The study aimed, firstly, to monitor the release of an antifungal drug, fluconazole, from a self-polymerizing poly(methyl methacrylate) (PMMA) denture base resin in artificial saliva and comparing it with the release in water; and secondly, to investigate the effect of the released drug on the growth of resistant and standard strains of Candida albicans. A high-performance liquid chromatography–ultra-violet (HPLC–UV) method was used in the analysis of the released eluates into distilled water from self-polymerized PMMA discs doped with the 10% fluconazole antifungal drug. The efficacy of the released drug against resistant and standard strains of C. albicans was monitored, using agar diffusion method. The results showed that fluconazole, can be successfully incorporated with the self-polymerized PMMA. The findings suggest that the drug leaches steadily out of the PMMA resin into artificial saliva and distilled water at mouth temperature and that sustained drug release continued throughout the 28 days test period. It was shown that the released drug demonstrated antifungal activity against both standard and resistant C. albicans. The findings of this investigation have a clinical value in terms of their significant contribution to the treatment of fungal infections of the oral cavity. The sustained release of antifungal drug from the PMMA resin clearly constitutes a new dosage form of the drug via the poly(methyl methacrylate) delivery system.     

Investigation of heat transfer augmentation in a horizontal tube using different rectangular cut ring inserts

Experimental and computational investigations have studied the heat transfer, friction factor, and enhancement of heat transfer in a horizontal tube equipped with rectangular cut ring inserts and different diameter ratios (D/d) and pitch-to-tube diameter ratios (p/d_t). In the present study, air having a Reynolds no. range of 6700–20,100 was used as a working fluid. Three diameter ratios (D/d) were considered experimentally and numerically as 1.2, 1.25, and 1.3, and the pitch-to-tube diameter ratio (p/d_t) was (1, 0.625, and 0.5). Air was forced as working fluid through the tube and a uniform heat flux of 2000, 3500, and 5000 W/m² was applied through the tube's exterior surface. On the basis of the turbulence model k–ɛ with various parameters, three-dimensional numerical simulations using the ANSYS Fluent software 17.2 were investigated. Under the same working conditions, the results manifested a higher heat transfer rate and friction factor as compared to the plain tube. The results evinced that the Nusselt number for a horizontal tube equipped with rectangular cut ring inserts having various pitch ratios and diameter ratios is discovered to be higher than that for the plain tube. With the increased ring spacing, the overall improvement in heat transfer occurred. And, with a rise in Re, the total enhancement ratio decreased. Consequently, the greatest overall improvement attained was 38% at Reynolds number (Re = 12,860) with the pitch ratio (p/d_t = 1). The three diameter ratios (D/d) of 1.3, 1.25, and 1.2 gives in this study the average thermal performance factor in the value of 1.6, 1.5, and 1.4, respectively. Using the Nusselt number and friction factor, the results are correlated as a function of the Reynolds number, diameter ratio, and pitch ratio.     

Phase transformation behavior of zinc metastannates obtained by aqueous precipitation at different temperatures

Phase transformation studies in ZnO–SnO₂ system from zinc metastannate (ZnSnO₃) to zinc orthostannate (Zn₂SnO₄) with annealing temperature are reported. Non-centrosymmetric oxides show unique symmetry dependent and spontaneous polarization properties, which are technologically important. ZnSnO₃ particles were synthesized by a simple aqueous synthesis at low temperatures designed with the assistance of potential–pH diagrams. ZnSnO₃ particles synthesized at 4 °C are more porous losing the ilmenite structure upon annealing at 200 °C, while the other samples prepared at higher temperatures (25–65 °C) becomes amorphous at 300 °C. The phase transformation into the inverse spinel orthostannate phase occurs around 750 °C in all the samples.