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Resultados 2911-2920 de 4,929
Study on dynamic adsorption of p-nitrophenol by multi-walled carbon nanotubes dispersed cyclodextrin
2019
Zhang, Lizhu | Tan, Wei | Duan, Zhenjuan | Bai, Mei | Li, Qiuliang | Zhao, Zhibiao | Yang, Min | Wang, Hongbin
In this paper, the modified multi-walled carbon nanotubes were prepared by β-cyclodextrin denoted as β-CD-MWNTs. The structure and morphology of β-CD-MWNTs was characterized by TEM and the dynamic adsorption of p-nitrophenol on β-CD-MWNTs was studied by the Thomas model. Some affecting factors of dynamic adsorption and the adsorbent regeneration process such as the sewage concentration, the amount of absorbent in column, including the type of reagent, solid-liquid ratio, regeneration time, and regeneration times were investigated and optimized. The results indicated that the p-nitrophenol removal rate could reach 84% under stuffing 2 g β-CD-MWNTs. The curves of p-nitrophenol’s dynamic adsorption conformed to the Thomas model. Moreover, the adsorption capacity of regenerated β-CD-MWNTs was similar to the fresh β-CD-MWNT column. The optimal conditions of regenerations of β-CD-MWNTs were shown as follows: the type of reagent is anhydrous ethanol, the solid-liquid ratio is 200:40 (mg/mL) and the regeneration time is 120 min.
Mostrar más [+] Menos [-]Transcriptome analysis of Oryza sativa in responses to different concentrations of thiocyanate
2019
Lin, Yu-Juan | Yu, Xiao-Zhang | Zhang, Qing
Effective concentrations of potassium thiocyanate (KSCN) to rice seedlings were experimentally determined using relative growth rate as a sensitive endpoint. Agilent 44-K rice microarray was used to profile the molecular responses of rice seedlings exposed to thiocyanate ion (SCN⁻) at three different effective concentrations (EC₁₀, EC₂₀, and EC₅₀). A total of 18,498 known genes were collected from SCN-treated rice microarray analysis. Out of all, 1603, 1882, and 5085 differentially expressed genes (DEGs) were observed at EC₁₀, EC₂₀, and EC₅₀ concentrations, respectively. More upregulated/downregulated DEGs were detected in shoots than in roots after SCN⁻ exposure. Gene functions and pathway enrichment analysis of DEGs indicated that different effective concentrations of SCN⁻ resulted in multiple enriched GO categories and KEGG pathways and outcomes were quite tissue-specific. Different regulations and adaptations of gene expression in molecular function (MF), biological process (BP), and cellular components (CC) were observed in rice tissues at different effective concentrations of SCN⁻, suggesting their different responsive and adaptive strategies. Information collected here presents a detailed description of SCN-induced alternations of gene expression in rice seedlings and provide valuable information for further searching specific genes participating in transportation, phytotoxic responses, and detoxification of SCN⁻ in rice seedlings.
Mostrar más [+] Menos [-]Comparison of Chlorella vulgaris and Chlorella sorokiniana pa.91 in post treatment of dairy wastewater treatment plant effluents
2019
Asadi, Pariya | Rad, Hassan Amini | Qaderi, Farhad
Treatment of wastewater by using of microalgae is a cost-effective system. Chlorella sorokiniana pa.91 and Chlorella vulgaris were studied in this research. Chlorella sorokiniana pa.91 was isolated from the dairy wastewater. In this study, treated wastewaters in preliminary and secondary treatment units of dairy wastewater treatment plant were used as medium. Maximum growth of two species of microalgae was examined in these two mediums, and also, nutrient removal was studied. The performance of two species of microalgae was studied on laboratory scale at different temperatures and light intensities. The best observed temperatures for Chlorella vulgaris and Chlorella sorokiniana pa.91 were 25 and 28 °C, respectively, and the best observed performance for them was obtained at 7500 lx. The values of specific growth rate and biomass productivity in effluent of preliminary treatment unit for Chlorella vulgaris were 0.331 day⁻¹ and 0.214 g L⁻ˡ day⁻¹, respectively, and for Chlorella sorokiniana pa.91 were 0.375 day⁻¹ and 0.233 g L⁻ˡ day⁻¹, respectively. Also, these parameters for Chlorella vulgaris in effluent of secondary treatment unit were determined 0.359 day⁻¹ and 0.166 g L⁻ˡ day⁻¹, respectively, and for Chlorella sorokiniana pa.91 were obtained 0.422 day⁻¹ and 0.185 g L⁻ˡ day⁻¹, respectively. The removal efficiency of nitrate, ammonia, phosphate, and chemical oxygen demand for Chlorella sorokiniana pa.91 and Chlorella vulgaris in both of effluents was more than 80%. Based on the results, effluent of treatment plants can be a suitable microalgae growth medium, and the microalgae can be used as effective post treatment system.
Mostrar más [+] Menos [-]Improvement of bioethanol production from pomegranate peels via acidic pretreatment and enzymatic hydrolysis
2019
Demiray, Ekin | Karatay, Sevgi Ertuğrul | Dönmez, Gönül
The aim of this study was to improve the ethanol production from pomegranate peels (PPs). Therefore, the effect of enzymatic hydrolysis and different pretreatments on ethanol production by yeasts was examined. There were three different enzyme concentrations (3.6, 7.2, 14.4 FPU/g substrate) tested for enzymatic hydrolysis, and four different PP media, such as WSPP (whole slurry of PP), LFPP (liquid fraction of PP), WSFPP (washed solid fraction of PP) and N-WSFPP (non-washed solid fraction of PP), were prepared. Bioethanol production was monitored for 96 h. Maximum ethanol concentrations were obtained at WSPP medium as 12.69 g/L, 14.35 g/L and 4.23 g/L in Saccharomyces cerevisiae, Kluyveromyces marxianus and Pichia stipitis, respectively. On the other hand, the washing step of biomass increased the kinetic parameters dramatically and the highest theoretical ethanol yields and YP/S values were obtained from WSFPP medium in all tested yeasts. Theoretical ethanol yields were 97.8%, 98.7% and 35.5% for S. cerevisiae, K. marxianus and P. stipitis, respectively. Qₚ values were observed as 0.98 g/L h, 0.99 g/L h and 0.04 g/L h for the same yeasts. The highest YP/S values were detected as 0.50 g/g for S. cerevisiae, 0.50 g/g for K. marxianus and 0.30 g/g for P. stipitis in the washed pomegranate peel biomass.
Mostrar más [+] Menos [-]Associations between mercury exposure and the risk of nonalcoholic fatty liver disease (NAFLD) in US adolescents
2019
Chen, Runsen | Xu, Yang | Xu, Cheng | Shu, Yaqin | Ma, Siyu | Lu, Changgui | Mo, Xuming
Little is known regarding the effects of environmental mercury (Hg) exposure on liver dysfunction in adolescents. We aimed to explore the association between Hg exposure and the risk of nonalcoholic fatty liver disease (NAFLD) in the adolescent population. The cross-sectional associations between blood Hg concentrations and serum alanine aminotransferase (ALT) levels, a surrogate for suspected NAFLD, were evaluated using data from adolescents (aged 12–17 years old) who participated in the National Health and Nutrition Examination Survey (NHANES), 1999–2014. A final sample of 6389 adolescents was analysed. Elevated ALT was defined as > 25 IU/L and > 22 IU/L for boys and girls ≤ 17 years old, respectively. Odds ratios (ORs) of Hg levels in association with serum ALT levels were estimated using a logistic regression after adjusting for gender, age, ethnicity, serum cotinine, body mass index, the poverty income ratio, and NHANES cycles. The median blood Hg level was 0.73 ± 0.91 μg/L amongst US adolescents. In the adjusted model, the ORs of elevated ALT levels of those in the 4th quartile were higher amongst non-Hispanic white adolescents (OR = 1.76, 95% CI 1.20, 2.59; P = 0.035) and those who were normal or underweight (OR = 1.41, 95% CI 1.08, 1.85; P = 0.020). No association was observed for the other variables. Our results indicate that the positive association between blood Hg exposure and the risk of NAFLD in US adolescents is the highest amongst non-Hispanic white and those who are normal or underweight, regardless of ethnicity. More research is necessary to confirm this association and to clarify the potential mechanisms.
Mostrar más [+] Menos [-]Natural resources, globalization, and economic growth: evidence from Pakistan
2019
Hassan, Syed Tauseef | Xia, Enjun | Huang, Jieping | Khan, Noor Hashim | Iqbal, Kashif
Globalization is increasingly a driving force behind vibrant economies around the world. This paper discusses the impact of globalization and natural resources on economic growth from 1970 to 2014 in Pakistan. Based on an auto-regressive distributive lag (ARDL) model, the paper infers that globalization promotes economic growth in Pakistan. Natural resources also contribute to economic growth, as the causality results suggest bi-directional causality between globalization and use of natural resources. Policy implications are that countries should emphasize security, increase exports, encourage technological strength, and increase its intellectual management capacity.
Mostrar más [+] Menos [-]Natural disasters and Malaysian economic growth: policy reforms for disasters management
2019
Qureshi, Muhammad Imran | Yusoff, Rosman Md | Hishan, Sanil S. | Alam, ASA Ferdous | Zaman, Khalid | Rasli, Amran Md
The natural catastrophic events largely damage the country’s sustainability agenda through massive human fatalities and infrastructure destruction. Although it is partially supported the economic growth through the channel of “Schumpeter creative destruction” hypothesis, however, it may not be sustained in the long-run. This study examined the long-run and causal relationships between natural disasters (i.e., floods, storm, and epidemic) and per capita income by controlling FDI inflows and foreign aid in the context of Malaysia, during the period of 1965–2016. The study employed time series cointegration technique, i.e., autoregressive distributed lag (ARDL)-bounds testing approach for robust inferences. The results show that flood, storm, and epidemic disasters substantially decrease the country’s per capita income, while FDI inflows and foreign aid largely supported the country’s economic growth in the short-run. These results are disappeared in the long-run, where flood and storm disasters exhibit the positive association with the economic growth to support the Schumpeter creative destruction hypothesis. The foreign aid decreases the per capita income and does not maintain the “aid-effectiveness” hypotheses in a given country. The causality estimates confirmed the disaster-led growth hypothesis, as the causality estimates running from (i) storm to per capita income, (ii) epidemic to per capita income, and (iii) storm to foreign aid. The results emphasized for making disaster action plans to reduce human fatalities and infrastructure for sustainable development.
Mostrar más [+] Menos [-]Investigating the drinking and surface water quality and associated health risks in a semi-arid multi-industrial metropolis (Faisalabad), Pakistan
2019
Mahfooz, Yusra | Yasar, Abdullah | Sohail, Muhammad Tayyab | Tabinda, Amtul Bari | Rasheed, Rizwan | Irshad, Samina | Yousaf, Balal
Urban areas under the influence of multi-industrial activities with arid and semi-arid environments witness the significant increase in environmental pollution especially in the water sector. The present study evaluated the water quality and associated health risk assessment through heavy metal pollution. Drinking (n = 48) and surface (n = 37) water samples were collected from semi-arid multi-industrial metropolis, Faisalabad, Pakistan. Physio-chemical and biological parameters and different metals (Al, As, Ba, Cd, Cr, Cu, Fe, Pb, Ni and Zn) were investigated using standard procedures and multivariate water quality assessments. Many physio-chemical and biological parameters and metals especially arsenic were exceeding the permissible limit of Punjab environmental quality standards and the World Health Organization. The results from water quality index showed that < 56% samples have poor, < 8% have very poor and < 6% have unsuitable water quality for drinking purposes. Water quality for the Gugera Branch Canal was found suitable with medium sodium (alkalinity) and salinity hazards, while it was found poor with magnesium absorption ratio. Hazard quotient (HQ) values for arsenic were found at the threshold level (HQ > 1) and carcinogenicity was found in case of arsenic and chromium (1 × 10⁻⁴) in adults and children. Semi-arid weather combined with different anthropogenic activities and unusual water features provoked metal contamination. Results of the present study can deliver basic information for effective management of water in the most populous and industrial areas.
Mostrar más [+] Menos [-]A novel superparamagnetic micro-nano-bio-adsorbent PDA/Fe3O4/BC for removal of hexavalent chromium ions from simulated and electroplating wastewater
2019
In order to improve the adsorption efficiency of the adsorbent and solve the problem of separation difficulty, a novel superparamagnetic micro-nano-bio-adsorbent (PDA/Fe₃O₄/BC) was prepared by in situ self-assembly of polydopamine (PDA). The results of scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), X-ray photoelectron spectrometer (XPS), and vibrating sample magnetometer (VSM) characterization showed that the size of bio-adsorbent was about 200 nm. PDA and Fe₃O₄ modifications increased the specific surface area of adsorbent, changed the surface functional group of biochar (BC), and made the adsorbent have super-high magnetization (294.76 emu g⁻¹). PDA/Fe₃O₄/BC was applied to treat Cr wastewater. The results show that the adsorption of Cr by PDA/Fe₃O₄/BC includes single-layer and multilayer adsorption. The adsorption follows the pseudo-second-order kinetic model. The adsorption is spontaneous and endothermic, and its maximum adsorption capacity and activation energy are 25.25 mg g⁻¹ at 318 K and 23.108 kJ mol⁻¹, respectively. After adsorption treatment, PDA/Fe₃O₄/BC still possesses high magnetization (233.04 emu g⁻¹). PDA/Fe₃O₄/BC can treat actual electroplating wastewater with Cr(VI) concentration from 20 mg L⁻¹ to less than 0.2 mg L⁻¹, which met the PRC discharge standard (GB/21900-2008) of electroplating pollutants. Graphical abstract
Mostrar más [+] Menos [-]Polychlorinated biphenyl 126 exposure in rats alters skeletal muscle mitochondrial function
2019
In the past few years, polychlorinated biphenyls (PCBs), a class of environmental pollutants, have been associated with metabolism dysregulation. Muscle is one of the key regulators of metabolism because of its mass and its important role in terms of glucose consumption and glucose storage. It has been shown that muscle alterations, such as oxidative stress and mitochondrial dysfunction, contribute significantly to the development of metabolic diseases. No study has yet investigated the toxicological effect of PCBs on muscle mitochondrial function and oxidative stress in vivo. The aim of this study was to assess the effect of PCB126 in vivo exposure (single dose of 1.05 μmol/kg) on muscle mitochondrial function and oxidative stress in rats. PCB126-treated rats showed a marked increase in Cyp1a1 mRNA levels in skeletal muscles in association with a 40% reduction in state 3 oxygen consumption rate measured with complex I substrates in permeabilized muscle fibers. Furthermore, PCB126 exposure altered the expression of some enzymes involved in ROS detoxification such as catalase and glutaredoxin 2. Our results highlight for the first time a toxic effect of coplanar PCBs on skeletal muscle mitochondrial function and oxidative stress. This suggests that acute PCB exposure, by affecting muscle metabolism, could contribute to the development of metabolic disorders. Studies are needed to determine if lower-level but longer-term PCB exposure exhibits the same effect.
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