خيارات البحث
النتائج 3521 - 3530 من 5,152
Quantitative mechanisms of cadmium adsorption on rice straw- and swine manure-derived biochars النص الكامل
2018
We quantified and investigated mechanisms for Cd²⁺ adsorption on biochars produced from plant residual and animal waste at various temperatures. Ten biochars were produced by pyrolysis of rice straw (RB) and swine manure (SB) at 300–700 °C and characterized. The Cd²⁺ adsorption isotherms, adsorption kinetics, and desorption characteristics were studied via a series of batch experiments, and Cd²⁺-loaded biochars were analyzed by SEM–EDS and XRD. The total Cd²⁺ adsorption capacity (Qc) increased with pyrolysis temperature for both biochars, however, rice straw-derived biochars had greater Qc than swine manure-derived biochars; hence, the biochar derived from rice straw at 700 °C (RB700) had the largest Qc, 64.4 mg g⁻¹, of all studied biochars. Cadmium adsorption mechanisms in this study involved precipitation with minerals (Qcₚ), cation exchange (Qcᵢ), complexation with surface functional groups (Qcₒ), and Cd-π interactions (Qcπ). Both the pyrolysis temperature and feedstock affected the quantitative contributions of the various adsorption mechanisms. The relative percent contributions to Qc for Cd²⁺ adsorption by RB and SB were 32.9–72.9% and 35.0–72.5% for Qcₚ, 21.7–50.9% and 20.4–43.3% for Qcᵢ, 2.2–14.8% and 1.4–18.8% for Qcₒ, and 1.4–3.1% and 3.0–5.8% for Qcπ, respectively. For biochars produced at higher pyrolysis temperatures, the contributions of Qcₚ and Qcπ to adsorption increased, while the contributions of Qcᵢ and Qcₒ decreased. Generally, Qcₚ dominated Cd²⁺ adsorption by high-temperature biochars (700 °C) (accounting for approximately 73% of Qc), and Qcᵢ was the most prominent mechanism for low-temperature biochars (400 °C) (accounting for 43.3–50.9% of Qc). Results suggested that biochar derived from rice straw is a promising adsorbent for the Cd²⁺ removal from wastewater and that the low-temperature biochars may outperform the high-temperature biochars for Cd²⁺ immobilization in acidic water or soils.
اظهر المزيد [+] اقل [-]Influence of sex on biomarkers of oxidative stress in the kidney, lungs, and liver of rabbits after exposure to diazinon النص الكامل
2018
Influence of sex on biomarkers of oxidative stress in the kidney, lungs, and liver of rabbits after exposure to diazinon النص الكامل
2018
The present study evaluated the effect of two oral doses of the pesticide diazinon (25 and 125 mg/kg bw) on four biochemical parameters (malondialdehyde and glutathione levels, and catalase and glutathione S-transferase enzymatic activities) in the kidney, lungs, and liver of rabbit after 10 days of exposure. Malondialdehyde levels were significantly greater in exposed animals compared to controls, especially in the animals exposed to the higher dose of the pesticide. This result was reflected in the glutathione levels, which were significantly lower at that same higher dose. Catalase activity was also inhibited by the higher dose of the pesticide in all three organs analysed, whereas inhibition of glutathione S-transferase activity was only significant for the kidney and lungs. There were some slight differences between the sexes: taking the results for all three organs, the higher dose of diazinon resulted in a clearly significant inhibitory effect on the catalase activity and glutathione levels in males, and a significant enhancing effect on the malondialdehyde levels in females. These results help to confirm the interest of considering such endogenous factors in future ecotoxicological studies, and that the four biomarkers considered are suitable for reflecting the toxic effects of diazinon on rabbits, especially the effects related to oxidative stress. Graphical abstract
اظهر المزيد [+] اقل [-]Influence of sex on biomarkers of oxidative stress in the kidney, lungs, and liver of rabbits after exposure to diazinon النص الكامل
2018
Hernández Moreno, David | Míguez-Santiyán, María Prado | Soler, Francisco | Pérez-López, Marcos
The present study evaluated the effect of two oral doses of the pesticide diazinon (25 and 125 mg/kg bw) on four biochemical parameters (malondialdehyde and glutathione levels, and catalase and glutathione S-transferase enzymatic activities) in the kidney, lungs, and liver of rabbit after 10 days of exposure. Malondialdehyde levels were significantly greater in exposed animals compared to controls, especially in the animals exposed to the higher dose of the pesticide. This result was reflected in the glutathione levels, which were significantly lower at that same higher dose. Catalase activitywas also inhibited by the higher dose of the pesticide in all three organs analysed, whereas inhibition of glutathione S-transferase activity was only significant for the kidney and lungs. There were some slight differences between the sexes: taking the results for all three organs, the higher dose of diazinon resulted in a clearly significant inhibitory effect on the catalase activity and glutathione levels in males, and a significant enhancing effect on the malondialdehyde levels in females. These results help to confirm the interest of considering such endogenous factors in future ecotoxicological studies, and that the four biomarkers considered are suitable for reflecting the toxic effects of diazinon on rabbits, especially the effects related to oxidative stress.
اظهر المزيد [+] اقل [-]Sustainable survival under climatic extremes: linking flood risk mitigation and coping with flood damages in rural Pakistan النص الكامل
2018
Various measures are adopted by flood-prone households for the mitigation of flood risk along with various post-flood coping strategies. We analyze the role of various ex ante household-level flood mitigation strategies in influencing riverine flood damages. The study also presents an account on the linkages of various ex post coping strategies and flood damages experienced in a flood event in Pakistan. For achieving a uniform flood damage indicator, polychoric principle component analysis (PCA) is employed to construct a composite flood damage index considering various aspects of economic, social, and psychological impacts of a flood event. The adjusted flood damage index is regressed on various socioeconomic features and ex ante mitigation actions to know their effect on the former. Results indicate that distance from river, elevating house, and pre-shifting investigating about flooding problem help in significantly reducing the overall flood damages. Likewise, group-based actions like voting political candidates based on their flood-control promises, organizing grass-root group meetings, and raising voices through memos/petitions are found to significantly reduce flood-related damages while leaving house premises before flooding is found to increase the overall flood damage. Post-flood coping strategies comprise of social and financial support along with some livelihood diversification and disinvestment strategies such as selling livestock, jewelry, and withdrawing children from schools. Borrowing money, reducing food consumption, and agricultural diversification are more prevalent strategies among low and medium damage groups while consuming savings is more conspicuous among high damage group. The study concludes with the emphasis on policy interventions for effective early warning, location-specific flood intensity information, and proper streamlining of planning process and compensation system.
اظهر المزيد [+] اقل [-]Comparative study of the direct black removal by Fe, Cu, and Fe/Cu nanoparticles النص الكامل
2018
Ourique, Mariane F. | Sousa, Paloma V. F. | Oliveira, André F. | Lopes, Renata P.
In this study, direct black dye removal was investigated using iron nanoparticles (Fe NPs), copper (Cu NPs), and Fe/Cu (Fe/Cu NPs). NPs were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Using a dose of 0.25 g L⁻¹ of Fe, Cu, and Fe/Cu NPs, a degradation efficiency of 13, 26, and 43% respectively was obtained. For the 1.00 g L⁻¹ dose, the efficiency increased to 100, 43, and 100%, respectively. Studies in anoxic and oxic conditions presented degradation rates, respectively, of 100 and 30% for Fe NPs, 90 and 50% for Fe/Cu NPs, and 40% in both reactions for Cu NPs, indicating that the mechanism of dye degradation by NPs is predominantly reducing under the conditions studied. The addition of EDTA decreased the dye removal rate for Fe, Cu, and Fe/Cu NPs at 27, 10, and 35%, respectively. In addition to the degradation, the adsorption phenomena of the by-products formed during the reaction were confirmed by the Fourier transform infrared (FTIR) analysis and verified by the desorption tests. Fe and Fe/Cu NPs showed the highest efficiency in direct black dye reductive degradation and adsorption of by-products, removing 100% of the dye at a dose of 1 g L⁻¹ within 10 min of reaction. Graphical abstracts ᅟ
اظهر المزيد [+] اقل [-]Leachable lead and cadmium in microwave-heated ceramic cups: possible health hazard to human النص الكامل
2018
Mandal, Priyanka Rani | Das, Suchismita
In this study, we assessed the leachability as well as health risk associated with the consumption from glazed, colourful, ceramic cups, containing lead and cadmium. Both metals leached into the 2.5-min microwave-heated (convection mode, at 140 °C) double-distilled water in concentrations above 0.5 mg/L, the permissible limits of leachable Pb and Cd in ceramic mugs set by United States Food and Drug Administration (US FDA). On an average, significantly higher Pb leached in new cups, 7.69 ± 0.56 mg/L, compared to that in old cups, 3.15 ± 0.15 mg/L. Cd leached similarly in both old (1.97 ± 0.14 mg/L) and new cups (1.57 ± 0.005 mg/L). The chronic daily intake of Pb by children and adults, respectively, consuming from new cups were 1.3–5× and 1.28–6× more than that from old cups. In both the cases, intake values far exceeded WHO reference dose of 0.0006 mg Pb/kg bw/day in children (< 11 years) and 0.0013 mg Pb/kg bw/day in adults. Such levels of Pb consumption in children might be predicted to be associated with decrement in IQ by at least 1 point and adverse effects in adults, especially, women of childbearing age. The daily intake of Cd from these cups ranged from 0.002–0.049 mg/kg bw/day, which was also above permissible limit. Consequently, high hazard quotient and hazard index (both more than 1) were observed for these metals, which might impart individual as well as cumulative effects on the health. Thus, apart from other dietary as well as inhalation sources of contaminants (which were not studied here), regular consumption of beverages alone in glazed, ceramic cups increased chances of Pb- and Cd-related health risks to humans.
اظهر المزيد [+] اقل [-]Cd and Pb accumulation characteristics of phytostabilizer Athyrium wardii (Hook.) grown in soils contaminated with Cd and Pb النص الكامل
2018
Zhan, Juan | Li, Tingxuan | Yu, Haiying | Zhang, Xizhou
Interactions between heavy metals in soil could affect soil heavy metal availability and plant uptake. Thus, in this study, Cd and Pb accumulation as well as plant growth of the mining ecotype (ME) and non-mining ecotype (NME) of Athyrium wardii (Hook.) in response to the exposure of Cd and Pb was investigated by a pot experiment. Although the exposure of Cd in combination with Pb further inhibited the growth of the two ecotypes in comparison with the exposure of single Cd or Pb, the ME presented lower biomass decline for the whole plant (22.0%–70.0%) than the NME among most treatments. The presence of Pb promoted Cd accumulation both in above-ground and under-ground parts of the ME. Cd concentrations in under-ground parts of the ME decreased when exposed to higher concentrations of Pb (> 600 mg kg⁻¹). Meanwhile, the presence of Cd inhibited Pb accumulation in above-ground parts of the ME and promoted Pb accumulation in under-ground parts of the ME. Pb concentrations in under-ground parts of the ME decreased when soil Cd concentrations were more than 25 mg kg⁻¹. The partial correlation analysis further demonstrated that the interactions between Cd and Pb stimulated Cd accumulation both in above-ground and under-ground parts of the ME and Pb accumulation in under-ground parts of the ME, while inhibited Pb accumulation in above-ground parts of the ME, showing great benefit for Pb phytostabilization by the ME. Among treatments, the bioaccumulation coefficients for Cd and Pb of the ME, varying from 2.71–31.05 and 20.09–78.06, were much higher than those of the NME. The translocation factors for Cd and Pb of the ME, varying from 0.26–0.52 and 0.01–0.10, were lower than those of the NME. These results indicate that the ME presented greater potential for the phytostabilization of soil contamination with Cd and Pb, especially for Pb.
اظهر المزيد [+] اقل [-]MicroRNA-411 promoted the osteosarcoma progression by suppressing MTSS1 expression النص الكامل
2018
Xu, Ning | Yang, Weiliang | Liu, Yang | Yan, Feng | Yu, Zhange
MicroRNAs (miRNAs) play crucial roles in the progression of different tumors. In our study, we investigated the expression and roles of miR-411 in human osteosarcoma. In this study, we first confirmed that the miR-411 expression was higher in the serum of patients with osteosarcoma than in the serum of healthy volunteers. In addition, we found that the miR-411 expression was upregulated in the osteosarcoma tissues compared to that in the matched normal bone tissues. We also demonstrated that the miR-411 expression was upregulated in the four osteosarcoma cell lines. Elevated expression of miR-411 promoted osteosarcoma cell proliferation and migration. Moreover, we identified that metastasis suppressor protein 1 (MTSS1) was a direct target gene of miR-411 in the osteosarcoma cell. We also demonstrated that the MTSS1 expression was downregulated in the osteosarcoma tissues compared to that in the matched normal bone tissues. In addition, MTSS1 expression level was inversely correlated with miR-411 expression in the osteosarcoma tissues. Furthermore, elevated expression of miR-411 enhanced the osteosarcoma cell proliferation and migration through inhibiting the MTSS1 expression. These data suggested that miR-411 played as oncogene in the osteosarcoma partly by inhibiting the MTSS1 expression.
اظهر المزيد [+] اقل [-]Assessment the activity of magnetic KOH/Fe3O4@Al2O3 core–shell nanocatalyst in transesterification reaction: effect of Fe/Al ratio on structural and performance النص الكامل
2018
Kazemifard, Sina | Nayebzadeh, Hamed | Saghatoleslami, Naser | Safakish, Ebrahim
Recently, biodiesel production using heterogeneous catalysts has been of great concern. However, simple separation of these catalysts from product mixtures is a problem of the process. In this study, series of magnetic KOH/Fe₃O₄@Al₂O₃ core–shell nanocatalysts were synthesized via the incipient wetness impregnation method and the effect of weight ratio of Fe₃O₄-to-Al₂O₃ (0.15–0.35) on the catalytic performance was assessed. The samples were characterized by XRD, FTIR, BET-BJH, VSM, SEM, TEM, and EDX analyses and their basicity was measured by the Hammett indicator method. The results revealed that although the magnetic KOH/Fe₃O₄@Al₂O₃ nanocatalyst with 25 wt% of Fe₃O₄ showed less activity as compared to those with 15 wt% of Fe3O4, it exhibited higher surface area and appropriate magnetic properties. The sample presented superparamagnetic properties with the magnetic strength of 1.25 emu/g that was simply recovered by using an external magnetic field. The nanocatalyst converted 98.8% of canola oil to biodiesel under reflux condition at the best operational conditions of 12 M ratio of methanol/oil, 4 wt% of catalyst and 6 h of reaction time. Moreover, the nanocatalyst showed high reusability such that it was reused several times without appreciable loss of its catalytic activity.
اظهر المزيد [+] اقل [-]Rapid monitoring and evaluation of a community-led total sanitation program using smartphones النص الكامل
2018
Ravindra, Khaiwal | Mor, Suman
India accounts for around 50% of the world’s open defecation, and under a World Bank initiative, a rural district was selected to be the first open defecation-free (ODF) district in Punjab. Considering this, the current study aims to evaluate the application and impact of a smartphone-based instant messaging app (IMA) on the process of making Fatehgarh Sahib an ODF district. The District Administration involved the Water Supply and Sanitation Department, Non-government Organizations, and volunteers to promote the process of a community-led total sanitation. Proper training was provided to the volunteers to spread awareness about the triggering events, health impacts of open defecation, and monetary benefits of building new individual household latrine (IHHL). IMA was used as an aid to speed up monitoring and for the evaluation of a sanitation program. All the volunteers were connected to an IMA. This helped in providing a transparent and evidence-based field report on triggering events, follow-up activities, validation of existing IHHL, and monitoring of construction of new IHHL. IMA is a cost-effective tool as it is already being used by the volunteers and requires no additional cost (on the user or on the project) but requires a training on ethical uses of mobile and data safety.
اظهر المزيد [+] اقل [-]Immobilization of heavy metals in two contaminated soils using a modified magnesium silicate stabilizer النص الكامل
2018
Yuan, Xingzhong | Xiong, Ting | Wang, Hou | Wu, Zhibin | Jiang, Longbo | Zeng, Guangming | Li, Yue
Heavy metal contamination is a severe environmental issue over the world. A lot of work has been done to develop effective stabilizers. In the present work, hydrothermal carbon-modified magnesium silicate (MS-C) was synthesized and used for the remediation of two heavy metal-polluted soils with different physicochemical properties. Soil samples were exposed to different doses of MS-C over 60 days (1, 3, and 5 wt%). The toxicity characteristic leaching procedure (TCLP) and the community bureau of reference sequential extraction procedure (BCR) were used to evaluate the remediation efficiency. The bioavailability of heavy metals in both soils was reduced by 20–86.7%, and the toxicity of heavy metals was reduced by 26.6–73.2% after MS-C added. Meanwhile, soil pH and water soluble organic carbon (WSOC) were increased. In addition, soil microbial biomass was increased, which indicated the improvement of soil condition. The immobilization of heavy metals was mainly caused by electrostatic attraction and cation exchange between MS-C and heavy metals. The significantly negative correlation between extractable heavy metals and pH/WSOC indicated the positive role of pH/WSOC in metal stabilization. Thus, this new stabilizer holds great application potentials for both single and multi-metal-contaminated soil remediation. ᅟ Graphical abstract
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