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Determined Changes (determine + change)
Selected AbstractsExperimental model of a variable capacity compressorINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2009C. Aprea Abstract The refrigeration and heat pump systems are lately characterized by a remarkable evolution period. The principal reasons that have determined changes are the substitution of environmentally unfriendly refrigerants and the energy saving necessity. As fundamental component of a vapour compression plant, the compressor is an object of optimizations; the variation of the compressor speed, obtained regulating the supply current frequency of the compressor motor, allows to obtain energy savings. The principal aim of this paper is the determination of an experimental model that represents the variable speed reciprocating compressor working. In particular, equations that allow to get the refrigerant mass flow rate, the compressor input power and the cooling capacity in terms only of the frequency are obtained. The experimental model allows to determine the optimum frequency for each working condition and then the related energy saving. Copyright © 2008 John Wiley & Sons, Ltd. [source] Influence of subacute treatment of some plant growth regulators on serum marker enzymes and erythrocyte and tissue antioxidant defense and lipid peroxidation in ratsJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2006Ismail Celik Abstract This study aims to investigate the effects of the plant growth regulators (PGRs) (2,3,5-triiodobenzoic acid (TIBA), Naphthaleneacetic acid (NAA), and 2,4-dichlorofenoxyacetic acid (2,4-D)) on serum marker enzymes (aspartate aminotransferase (AST), alanin aminotransferase (ALT), creatine phosphokinase (CPK), and lactate dehydrogenase (LDH)), antioxidant defense systems (reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD), glutathione-S-transferase (GST), and catalase (CAT)), and lipid peroxidation content (malondialdehyde = MDA) in various tissues of rats. 50 and 100 ppm of PGRs as drinking water were administered orally to rats (Sprague,Dawley albino) ad libitum for 25 days continuously. The PGRs treatment caused different effects on the serum marker enzymes, antioxidant defense systems, and the MDA content in experimented rats compared to controls. Results showed that TIBA caused a significant decrease in serum AST activity with both the dosage whereas serum CPK was significantly increased with 100 ppm dosage of TIBA. Meanwhile, serum AST, CPK, and LDH activities were significantly increased with both dosage of NAA and 2,4-D. The lipid peroxidation end-product MDA significantly increased in the all tissues treated with both dosages of PGRs without any change in the brain and erythrocyte of rats treated with both the dosages of 2,4-D. The GSH depletion in the kidney and brain tissues of rats treated with both dosages of PGRs was found to be significant. Furthermore, the GSH depletion in the erythrocyte of rats treated with both dosages of PGRs except 50 ppm dosage of 2,4-D was significant too. Also, the GSH level in the liver was significantly depleted with 50 ppm of 2,4-D and NAA, whereas the GSH depletion in the same tissue did not significantly change with the treatment. The activity of antioxidant enzymes was also seriously affected by PGRs; SOD significantly decreased in the liver, heart, kidney, and brain of rats treated with both dosages of NAA, whereas the SOD activity in the erythrocytes, liver, and heart was either significantly decreased or not changed with two doses of 2,4-D and TIBA. Although the CAT activity significantly increased in the erythrocyte and brain of rats treated with both doses of PGRs, it was not changed in the liver, heart, and kidney. Meanwhile, the ancillary enzyme GR activity significantly increased in the brain, heart, and liver but decreased in the erythrocyte and kidney of rats treated with both doses of PGRs. The drug-metabolizing enzyme GST activity significantly increased in the heart and kidney but decreased in the brain and erythrocytes of rats treated with both dosages of PGRs. As a conclusion, the results indicate that PGRs might affect antioxidant potential enzymes, the activity of hepatic damage enzymes, and lipid peroxidation dose independently. Also, the rats resisted to oxidative stress via antioxidant mechanism but the antioxidant mechanism could not prevent the increases in lipid peroxidation in rat's tissues. These data, along with the determined changes, suggest that PGRs produced substantial systemic organ toxicity in the erythrocyte, liver, brain, heart, and kidney during the period of a 25-day subacute exposure. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:174,182, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20134 [source] Hildebrand and Hansen solubility parameters from Molecular Dynamics with applications to electronic nose polymer sensorsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2004M. Belmares Abstract We introduce the Cohesive Energy Density (CED) method, a multiple sampling Molecular Dynamics computer simulation procedure that may offer higher consistency in the estimation of Hildebrand and Hansen solubility parameters. The use of a multiple sampling technique, combined with a simple but consistent molecular force field and quantum mechanically determined atomic charges, allows for the precise determination of solubility parameters in a systematic way (, = 0.4 hildebrands). The CED method yields first-principles Hildebrand parameter predictions in good agreement with experiment [root-mean-square (rms) = 1.1 hildebrands]. We apply the CED method to model the Caltech electronic nose, an array of 20 polymer sensors. Sensors are built with conducting leads connected through thin-film polymers loaded with carbon black. Odorant detection relies on a change in electric resistivity of the polymer film as function of the amount of swelling caused by the odorant compound. The amount of swelling depends upon the chemical composition of the polymer and the odorant molecule. The pattern is unique, and unambiguously identifies the compound. Experimentally determined changes in relative resistivity of seven polymer sensors upon exposure to 24 solvent vapors were modeled with the CED estimated Hansen solubility components. Predictions of polymer sensor responses result in Pearson R2 coefficients between 0.82 and 0.99. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1814,1826, 2004 [source] Evaluating the cytotoxic doses of narrowband and broadband UVB in human keratinocytes, melanocytes, and fibroblastsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2008Tae-Ho Cho Summary Background: No comparative and simultaneous in vitro studies have been performed to determine the cytotoxic dose of narrowband UVB (NBUVB) and broadband UVB (BBUVB) for keratinocytes, melanocytes, and fibroblasts. Culture medium was often replaced with phosphate-buffered saline (PBS) before UV irradiation; however, its amount differed across studies. We determined the cytotoxic doses of NBUVB and BBUVB and tested for changes in viability according to the amount of PBS. Methods: We exposed cultured human keratinocytes, melanocytes, and fibroblasts to ultraviolet light in the range 12.5,1000 mJ/cm2 for NBUVB and 1.25,100 mJ/cm2 for BBUVB. The viability was assessed after 24 h. We also determined changes in viability at cytotoxic doses according to the amount of PBS (40, 80, and 120 ,l/well in a 96-well plate). Results: Cytotoxicity was observed at doses of 100, 200, and 400 mJ/cm2 for NBUVB and 5, 10, and 25 mJ/cm2 for BBUVB in keratinocytes, melanocytes, and fibroblasts, respectively. At cytotoxic doses, there was no change in viability according to the amount of PBS. Conclusions: Fibroblasts are more resistant to UVB irradiation, irrespective of the amount of NBUVB and BBUVB, than keratinocytes and melanocytes. The amount of PBS during irradiation had no effect on viability. [source] | ||||||||||