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101.
ABSTRACT: The thermal stability of carp G-actin was investigated by monitoring loss of actin polymerization ability. To determine the amount of native actin remaining after heat treatment, actin was labeled with a fluorescence reagent, N-(1-pyrene)iodoacetamide. The loss of polymerization ability of carp actin during heat treatment, at between 45 and 55°C, occurred faster than that of chicken actin. The inactivation rate was influenced by concentrations of ATP and Ca2+ in solution. With the increase of Ca2+ concentration, the inactivation of carp actin was markedly suppressed. Furthermore, the activation energy of the inactivation of carp actin obtained from an Arrhenius plot was similar to that of chicken actin. These results indicated that the thermal instability of carp G-actin was due to the low affinites of ATP and Ca2+ for carp actin described in a previous report. 相似文献
102.
The present study examines the pattern of accumulation of cadmium (Cd) and its biochemical effects on selected tissues of
a variety of African catfish (Clarias gariepinus), after exposure to various doses of Cd. The results obtained indicate that at the end of 21 days of exposure, the total
tissue organ cadmium concentration followed the pattern kidney > gill > liver > muscle for each of the exposure concentrations.
The levels of Cd in these organs were higher than those in ambient water. Moreover, while the rate of uptake of Cd increased
with time in the kidney, liver and muscle, it decreased in the gill. Superoxide dismutase (SOD) was significantly elevated
only in the kidney of catfish treated with 0.2 and 0.4 ppm of Cd for 7 days compared with the control. Conversely, gill SOD
was significantly decreased in the same concentrations of Cd-treated catfish relative to the control. Statistically similar
levels of SOD were observed in the liver, brain and muscle with all the treatments after the same duration of treatment. In
the fish exposed for 21 days, SOD activity was significantly decreased in the kidney with a corresponding increase in lipid
peroxidation (LPO), but it manifested only with the 0.2- and 0.4-ppm Cd treatment relative to the control. In the liver, however,
Cd exposure significantly increased SOD in the 0.2- and 0.4-ppm treatments of the same duration. In conclusion, the present
study indicates that the accumulation of Cd and its effect on SOD and LPO in C. gariepinus is dependent on concentration, tissue and time 相似文献
103.
104.
Treated wastewater (TWW) is an imperative nonconventional water resource for reuse in irrigation to cope with the water shortage and agricultural expansion in Egypt. The Bahr El-Baqar drain in Sharqia, Egypt, is one of the main drains in the Nile Delta that receives various types of wastewater. Monitoring and assessing the drain’s water quality were achieved by collecting georeferenced water samples along the drain during the 2015 summer and winter cropping seasons. Chemical, microbial, and parasitic analyses were performed. Additionally, surface soil samples irrigated with the drain water were gathered from the adjacent area to quantify the main physicochemical properties. Water analysis results revealed that the concentrations of most trace elements were within international standards and the Egyptian allowable levels for TWW reuse in agriculture. Oxygen depletion was observed for all samples collected. The microbial analysis indicated that there was fecal coliform contamination (>1000 per 100 mL) in the summer and winter samples. Concentrations of PO4 and SO4 were within the permissible level for irrigation use, whereas NH4, NO3, and MoO4 concentrations were higher than the recommended values for reusing Bahr El-Baqar water in irrigation. Based on the soil analysis results, Cd contamination was observed, whereas the Pb concentration in soils was slightly higher than its normal range. Mixing Bahr El-Baqar water with freshwater and implementing appropriate on-farm treatment before the reuse are recommended as a prerequisite for reusing Bahr El-Baqar water for irrigation. Bio-diesel fuel and energy oil crops are recommended for the studied region. 相似文献
105.
Daniel E. León Henry Zúñiga-Benítez Gustavo A. Peñuela Héctor D. Mansilla 《Water, air, and soil pollution》2017,228(9):361
This study presents the main results about the removal of the antibiotic cefotaxime (CTX) under simulated sunlight radiation using heterogeneous photocatalysis with titanium dioxide (TiO2) and zinc oxide (ZnO) in aqueous solutions. The effects of pH and catalyst initial load on pollutant removal were assessed considering the response surface methodology and a central composite circumscribed experimental design, which allowed to determine the optimized conditions that lead to a higher substrate elimination. Experimental results indicated that evaluated parameters have a significant effect on antibiotic removal in both TiO2 and ZnO suspensions. In addition, the role of photogenerated holes, hydroxyl, and superoxide anion radicals on CTX degradation was evaluated to clarify the reaction mechanism. Finally, analysis of the dissolved organic carbon content in solutions and the antibacterial activity of treated samples showed that photocatalytic treatments were able to reduce a considerable portion of the organic matter present in the systems and its antimicrobial activity. 相似文献
106.
Ni Yan Mengjiao Li Yali Liu Fei Liu Mark L. Brusseau 《Water, air, and soil pollution》2017,228(12):453
The efficacy of two oxidant systems, iron-activated hydrogen peroxide (H2O2) and iron-activated hydrogen peroxide coupled with persulfate (S2O8 2?), was investigated for treatment of two chlorinated organic compounds, trichloroethene (TCE) and 1,2-dichloroethane (DCA). Batch tests were conducted at multiple temperatures (10–50 °C) to investigate degradation kinetics and reaction thermodynamics. The influence of an inorganic salt, dihydrogen phosphate ion (H2PO4 ?), on oxidative degradation was also examined. The degradation of TCE was promoted in both systems, with greater degradation observed for higher temperatures. The inhibition effect of H2PO4 ? on the degradation of TCE increased with increasing temperature for the iron-activated H2O2 system but decreased for the iron-activated hydrogen peroxide-persulfate system. DCA degradation was limited in the iron-activated hydrogen peroxide system. Conversely, significant DCA degradation (87% in 48 h at 20 °C) occurred in the iron-activated hydrogen peroxide-persulfate system, indicating the crucial role of sulfate radical (SO4 ??) from persulfate on the oxidative degradation of DCA. The activation energy values varied from 37.7 to 72.9 kJ/mol, depending on the different reactants. Overall, the binary hydrogen peroxide-persulfate oxidant system exhibited better performance than hydrogen peroxide alone for TCE and DCA degradation. 相似文献
107.
Chen Meng Jianzhi Niu Xiang Li Ziteng Luo Xiaoqing Du Jie Du Xingna Lin Xinxiao Yu 《Journal of Soils and Sediments》2017,17(9):2357-2370
Purpose
Macropores have important effects on the movement of soil water, air, and chemical substances. However, the quantitative relationship between complex 3D soil macropore networks and forest communities remains unclear in the northern mountainous area in China. The objectives of this study were to (1) use industrial computed tomography (CT) scanning and image analysis to quantitatively analyze macropore networks in intact soil columns and (2) identify characteristics of soil macropore networks in different forest communities.Materials and methods
Intact soil columns (100-mm diameter, 300 mm long) were taken from six local forest communities with three replicates for a total of 18 samples. Industrial X-ray CT was used to scan soil samples; then, the scanned images were used to obtain the 3D images of rock fragments and macropore structures. Next, the macropore structure was quantified, including volume, diameter, surface area, length, angle, tortuosity, and number of macropores. This technique provided an accurate method to quantify the structure of macropores.Results and discussion
The analysis and results revealed that different forest communities influence soil macropore 3D structure significantly and in different ways. Macropores in mixed Pinus tabulaeformis, Castanea mollissima, and Ulmus pumila forest had the largest diameter, surface area, network density, and length density of macropores as well as the smallest mean tortuosity of soil macropores. This is caused by the fact that mixed forest soils had more complex root systems, better soil structure, and more biotic activity. Within the soils of a single forest community, macropore porosity, network density, surface area density, and length of macropores decreased with increased soil depth, because more roots and more biological activity were present in the surface soil.Conclusions
Advanced industrial CT technology can allow an accurate quantification of soil macropore structure. This is important because this type of structure has significant effects on soil water, air, and chemical transport. The results suggest that mixed forest is the best afforestation model in the northern mountainous area in China because of its ability to improve soil structure.108.
Yuanchun Yu Jingyu Yang Shucai Zeng Daoming Wu Douglass F. Jacobs Joshua L. Sloan 《Journal of Soils and Sediments》2017,17(9):2230-2238
Purpose
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is an important native tree species in China. Consecutive cropping traditionally occurs in Chinese fir plantations (CFPs), but this practice has resulted in productivity declines in subsequent rotations. This study was designed to better understand the change of soil properties in the continuous cropping CFPs.Materials and methods
We investigated soil pH, soil organic matter (SOM), and nutrient contents in different soil layers and in rhizosphere soil (RS) and non-rhizosphere soil (NRS) under CFPs of different ages and in different rotations.Results and discussion
In the upper (0–20 cm) soil layer, soil pH decreased, while SOM increased, beneath mature CFPs with consecutive rotations. Total nitrogen (TN), available potassium, and available phosphorus contents in the upper soil layers did not differ significantly with consecutive rotations. Soil pH in RS was significantly lower than in NRS under mature plantations of the third rotation. Soil organic matter, TN, and available nitrogen did not differ between RS and NRS. Available phosphorus in RS was consistently lower than in NRS, and was highly deficient in the third rotation.Conclusions
We conclude that no severe soil nutrient degradation occurred in the continuous cropping CFPs examined in this study, with soil acidification and phosphorus deficiency being two primary problems observed.109.
Purpose
Investigations of geochemical characteristics of sediments of the Zrmanja River estuary were done in order to determine the natural and anthropogenic factors influencing sediment composition in this area. For that purpose, spatial and temporal distribution of major and trace elements in the sediments and surrounding soils was studied.Materials and methods
Sediment and soil samples, including one marl sample, were collected at 28 locations. All samples were subjected to total digestion and subsequently analysed by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for total concentration of 20 elements (Ag, Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Rb, Sb, Sn, Sr, Ti and Y). Obtained concentrations and their normalized counterparts were used for assessment of factors influencing sedimentation in the study area.Results and discussion
The results of the analysis showed that the composition of sediments of the Zrmanja River estuary is primarily determined by the composition of bedrock, existing hydrodynamic conditions and the relative isolation of the studied basin. Nevertheless, anthropogenic influences were observed as well. The composition of the Zrmanja River sediments reflects the impact of the ex-alumina factory “Jadral” and transfer by wind of the material from its immediate surroundings to the water system of the Zrmanja River. In addition, sedimentation in the Zrmanja River was found to be influenced by the construction of reservoirs and the HE “Velebit”, hydroelectric power plant located in the Zrmanja watershed.Conclusions
The geochemical composition of recent sediments of the Zrmanja River estuary is controlled primarily by natural factors, although the influence of anthropogenic activities is also evident.110.