خيارات البحث
النتائج 2691 - 2700 من 4,896
Process Optimization for the Preparation of Activated Coke from Industrial Waste Using Response Surface Methodology
2019
Juanqin Xue, Xiande Jing, Shudi Hu, Yuhong Tian, Yonghui Song and Xinzhe Lan
Fine blue-coke and direct liquefaction residue of coal are byproducts in the process of coal chemical production. They were taken as raw materials for the preparation of activated coke by the activation of carbon dioxide. The conditions (activation temperature, activation time and carbon dioxide flow rate) for activated coke preparation were optimized by response surface methodology (RSM). Results showed that activation temperature and activation time had a significant effect on the activated coke iodine adsorption value. The synergistic effect of activation time and carbon dioxide flow had a great influence on iodine adsorption value of activated coke. RSM optimization experiment obtained the optimum activation conditions were activation temperature of 850°C, activation time of 90min and carbon dioxide flow rate of 60 mL/min. Under these conditions, the obtained activated coke iodine adsorption value can reach 401 mg/g, which could meet the needs of industrial desulphurization.
اظهر المزيد [+] اقل [-]Plumbum (Pb) in Rainwater in West Kalimantan: Impact of Plumbum (Pb) in Community Blood
2019
Khayan Khayan-Taufik Anwar-Slamet Wardoyo
The low coverage of drinking water in the West Kalimantan-Indonesia region because of the limited availability of decent water as a source of drinking water is the main trigger for the community to use rainwater as a source of drinking water. The way of storing rainwater through zinc roofs and environmental pollution conditions results in rainwater being a health concern for the community because of the content of Plumbum (Pb). In this study, the characteristics of rainwater in the West Kalimantan region were investigated from rainwater collected by people from homes with zinc roofs. Rainwater samples from the collection results were analysed for the presence of Plumbum (Pb). The impact of consuming rainwater is carried out by blood Pb examination. The main problem can analyse the existence of Plumbum (Pb) in rainwater against the content of Plumbum (Pb) in the blood. The results showed that there was a correlation of Pb content in rainwater with Pb content in the blood of people who consumed rainwater as water drink (p≤0.001).
اظهر المزيد [+] اقل [-]Policy Study on Adjustments to Electric Power Prices for China’s Air Pollution Abatement
2019
Kun Xiao and Jingdong Zhang
In the past decade, the deterioration in atmospheric quality caused by emissions of ambient particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5) has become an urgent problem in China. As this problem can be mainly attributed to the large amount of coal consumption, a strategy to promote electric power substitution was initiated, and in this case, cutting the price of electricity is considered useful. However, since it was announced that the price of electric power used in the service industry will be reduced by 10%, the proper target to cut the price of electric power used in the secondary industry was under debate. By using the computable general equilibrium (CGE) model, the policy to cut the price of electric power used in the secondary industry was simulated and the effects of the policy on the economy and the environment were explored. The results show that the policy to cut electric power prices will contribute to promoting the strategy of electricity substitution, and further contribute to environmental improvement. This policy can result in positive effects on the systems of the economy and the environment at the same time, and when the target to cut the price of electric power used in the secondary industry is –3%, the maximum positive effects will be obtained: gross domestic product (GDP) growth will be accelerated by 0.015‰, while PM2.5 emissions will be abated by 394.2 tons. Moreover, based on the unique cross-subsidy mechanism in China’s electric power industry, although residents’ consumption welfare can be fully compensated, less cross-subsidy will have a negative effect on the agriculture industry.
اظهر المزيد [+] اقل [-]Purification, Molecular Cloning and Expression of Three Key Saponin Hydrolases from Trichoderma reesei, Trichoderma viride and Aspergillus fumigatus
2019
Jiamin Huang, Yangyang Wang, Linshan Fang, JiaojunJin, Suhui Ye, Wenjing Dun and Yuling Zhu
Microbial transformation is an environment-friendly approach to produce diosgenin from natural plant tubers. However, improving the bioconversion efficiency of this process remains a challenge. Saponin hydrolase plays a major role during the transformation. a-rhamnase, b-glycosidase and C3 b-glycosidase have been identified as three key enzymes in the stepwise conversion of saponins to diosgenin. The three enzymes have not been molecularly characterized. Here, a-rhamnase, b-glycosidase and C3 b-glycosidase were purified from Trichoderma reesei, Trichoderma viride and Aspergillus fumigatus, respectively. SDS-polyacrylamide gel electrophoresis showed that the molecular masses of the three enzymes were approximately 60, 36 and 56 kDa, respectively. a-rhamnase could efficiently hydrolyse the terminal rhamnoside on the C3 site in saponins. b-glycosidase could cleave the terminal b-glycoside at the C3 position, while C3 b-glycosidase demonstrated significant affinity to the b-glycoside at the C3 position. The amino acid sequences of the three saponin hydrolases were determined. Reverse transcription-PCR was used to clone the three plasmids with lengths of approximately 1035, 1416 and 1752 bp from the strains and expressed in Escherichia coli. The recombinant saponin hydrolases from the recombinant strains also demonstrated the hydrolysing of rhamnoside and glycosides of saponins similar to those of the wild-type hydrolases from T. reesei, T. viride, and A. fumigatus. The findings could facilitate the construction of recombinant cells by gene fusion to produce diosgenin from plant tubers.
اظهر المزيد [+] اقل [-]Regeneration of Wind Power Waste Lubricating Oil by a Combination Use of Chitosan, Sodium Carbonate and Silica Gel
2019
Yanli Zhu, Youxian Zhang, Zhongyang Shi and Bo Li
Waste lubricant oil can be regenerated by flocculation and adsorption to get rid of impurities. In this work, the performance of flocculants (chitosan, sodium carbonate and sodium silicate) and sorbents (carclazyte and silica gel) were evaluated experimentally. The results showed that the combination of chitosan and sodium carbonate had beat results in removal of acid value and mechanical impurities. Silica gel contacting adsorption had the best colour removal. Thermal precipitation (80°C, 24h) was adopted as primary step before flocculation to wipe off heavier particulate matter. The best ratio of chitosan, sodium carbonate and silica gel was 1:1:1, and the best dosage of chitosan was 2% compared to oil. After the re-refining process, viscosity decreased from 186.34 (mm2/s, 40°C) to 155.21 (mm2/s, 40°C), the acid value from 0.26 (mg KOH/g) to 0.06 (mg KOH/g), mechanical impurities content from 3.62% to 1.41%, water content from 0.45% to 0.06%, and light absorbance from 4.31 to 1.17.
اظهر المزيد [+] اقل [-]Heavy Metal Accumulation in Some Fishes Preferred for Consumption by Egrets in Odisha, India
2019
Bibhu Prasad Panda, Biswajit Panda, Siba Prasad Parida, Biswajita Mahapatra, Aditya Kishore Dash and Abanti Pradhan
The reduction of wetlands due to the increase of urbanization and industrialization has been an emerging global concern and is a threat to the fish population. Fishes have been proved as excellent indicators of heavy metal contamination of the aquatic ecosystems. The present research aims to determine the metal accumulation in fishes of different wetlands. Fish samples were collected for analysis of different metals like lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn) by atomic absorption spectrophotometer. Pb concentration varies from 0.41-44.33 µg/g and found to be highest at Hirakud, whereas Cr, Cu and Zn were highest at Koraput which vary from 1.3-10.36 µg/g, 1.29-4.17 µg/g and 20.97-54.99 µg/g, respectively.
اظهر المزيد [+] اقل [-]Water Quality Situation of the Tha Chin River and the Riverbank Community’s Understanding
2019
Chitsanuphong Pratum, Noppol Arunrat, Sukanya Sereenonchai, Huang Jung-Chen and Tian Xu
The Tha Chin River is a branch river of the Chaophraya River, which is one of the four main rivers in the central area of Thailand. Currently, the Tha Chin River is experiencing serious problems regarding water quality. Our study was carried out to analyse the river quality status, classify the health of the river according to Water Quality Index (WQI) and assess the riverbank community’s understanding of the Tha Chin River water quality. The results indicated that the water quality in the estuary of the Tha Chin River has been seriously polluted. In addition, the results also found that the WQI of the wet period was significantly lower than that of the dry period at p-value < 0.05. While the results from the riverbank community’s understanding assessment revealed that they feel the water quality in this river is still good, especially in the upstream and the midstream. Therefore, the assessed water quality according to WQI method showed that the riverbank community had a misunderstanding of the water quality of the Tha Chin River.
اظهر المزيد [+] اقل [-]Environmental variations mediate duckweed (Lemna minor L.) sensitivity to copper exposure through phenotypic plasticity
2019
Roubeau Dumont, Eva | Larue, Camille | Pujol, Benoît | Lamaze, Thierry | Elger, Arnaud
Environmentally mediated sensitivity of Lemna minor to copper (Cu) was evaluated for the first time in three experiments: the effects of two levels of nutrient concentration, light irradiance or Cu pre-exposure were tested. Various Cu concentrations (ranging from 0.05 to 0.25 mg/L) were used to assess the sensitivity of L. minor to this metal, using one common strain previously acclimatized to two different levels of light intensity, nutrient enrichment and Cu pre-exposure. Our results showed a phenotypic plastic response of the relative growth rates based on frond number and fresh mass production, and maximum quantum yield of photosystem II (Fᵥ/Fₘ). Growth was affected by the three environmental conditions both prior and during Cu exposure, whereas Fᵥ/Fₘ was mostly affected during Cu exposure. Copper significantly influenced all the parameters measured in the three experiments. Environmental conditions significantly modified L. minor sensitivity to Cu in all experiments, with up to twofold difference depending on the treatment. Growth rate was the parameter that was most impacted. Our study revealed for the first time the existence of phenotypic plasticity in L. minor sensitivity to chemical contamination, and implies that environmental context needs to be taken into account for a relevant risk assessment.
اظهر المزيد [+] اقل [-]Tea Residue Boosts Dye Decolorization and Induces the Evolution of Bacterial Community
2019
Xie, Xuehui | Zheng, Xiulin | Yu, Chengzhi | Zhang, Qingyun | Wang, Yiqin | Cong, Junhao | Liu, Na | He, Zhenjiang | Yang, Bo | Liu, Jianshe
Considerable researches on removal of azo dyes have been reported in recent years, but few researchers have documented adsorption and/or transformation of anthraquinone dyes by physical, chemical, or biological treatment methods due to their fused aromatic structures. In this study, tea residue was found to have significant enhancement effect on the decolorization of anthraquinone dye reactive blue 19. This effect worked on different dye decolorizing bacterial florae and the natural bacterial flora from surface water and exhibited universal feature. Six single bacterial strains were isolated from bacterial flora DDMY2. Unexpectedly, all of them had poor decolorization capacity. High-throughput sequencing results revealed the community evolution of bacterial flora DDMY2 cultured with tea residue after 6 months and 12 months. It was found that the community structure changed dramatically because the influence of tea residue and the dominant functional genera, such as unclassified_o_Pseudomonadales, Stenotrophomonas, Bordetella, and Brevibacillus, was significantly enriched. Meanwhile, the evolved community structure could keep stable for a long time, resulting in the decolorization effect stabilized for a long time. This study provides the tea residue as the bioactivator that can be applied to boost the decolorization of dyes by various potential bacterial florae. It also enlarges our knowledge of making full use of biowaste in biological wastewater treatment.
اظهر المزيد [+] اقل [-]Ultrastructural damage and biochemical alterations in the testes of red palm weevils (Rhynchophorus ferrugineus) exposed to imidacloprid
2019
Alzahrani, Abdullah M.
Despite the widespread use of the insecticide imidacloprid (IMI), a neonicotinoid, there is an urgent need for documenting information related to its acute toxicity. Therefore, this study aims to explore the markers of IMI acute toxicity in the testes of the red palm weevil (Rhynchophorus ferrugineus). The LC₅₀ of IMI was determined at 15.7 ppm for male R. ferrugineus. We assessed biochemical alterations in the testes resulting from treatment with four IMI concentrations (10, 15, 20, and 30 ppm). A reduction in glutathione content and acetylcholine esterase activity followed the IMI concentration in a dependent manner. Catalase activity was inhibited only at 20 ppm, while it increased significantly at 30 ppm. Lipid peroxidation increased steadily as the IMI concentrations increased. Based on ultrastructural analyses of spermiogenic stages, acute IMI toxicity produced swelling and degeneration of spermatid mitochondria indicating structural imbalances in their membranes. Further, abnormal chromatin condensation in nuclei and even loss of sperm were also apparent. This study provides biochemical and ultrastructural indicators for acute toxicity resulting from IMI.
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