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Leaching of copper and zinc from the tailings sample obtained from a porcelain stone mine: feasibility, modeling, and optimization Full text
2020
Nozhati, Ramezan Ali | Azizi, Asghar
This research was aimed to investigate the leaching behavior of zinc and copper from a porcelain stone tailings sample using RSM-CCD modeling. The synergetic and individual effects of five main factors including liquid/solid ratio, sulfuric acid concentration, agitation speed, leaching time, and temperature were examined on the recoveries of zinc and copper. For this purpose, two 2F1 models with R² values of 0.9341 and 0.8693 were developed for the relationship between the leaching efficiencies of copper and zinc and effective terms, respectively. The results indicated that the leaching process was significantly influenced by the interactive effects between factors. The leaching recoveries increased by increasing all factors in the range studied. However, the recoveries were nearly independent of the agitation rate, indicating surface chemical reaction as the leaching kinetics controlling step. It was also found that the linear effect of temperature, the interaction effect of leaching time with liquid/solid ratio, and the interactive effect between sulfuric acid concentration and agitation rate had the greatest impact on the leaching rate of copper. Additionally, the linear effect of temperature and the interactive effect of temperature with agitation speed and liquid/solid ratio were distinguished to be the most effective factors on the recoveries of zinc. Moreover, the optimization was performed using desirability function approach, and the highest recoveries of copper (73.95%) and zinc (81.02%) were obtained at an acid concentration of 10%, 300 rpm agitation rate, 10 mL/g liquid/solid ratio, 35 °C temperature, and 75 min leaching time.
Show more [+] Less [-]Examining the asymmetric effects of fiscal policy instruments on environmental quality in Asian economies Full text
2020
Ullah, Sana | Majeed, Muhammad Tariq | Chishti, Muhammad Zubair
Empirical studies pertaining to the effects of fiscal policy instruments on environmental quality have provided mixed evidence. We consider the asymmetric effects of fiscal policy instruments on environmental quality for the top ten Asian carbon emitters over the period 1981–2018. We go beyond the literature and claim that the effects could be asymmetric. More specifically, we found that a positive shock in government expenditure will worsen environmental quality in Malaysia, UAE, Thailand, Indonesia, Turkey, Iran, India, and China, and improve it in Japan. On the other hand, we found that cutting government expenditure will improve environmental quality in these economies and will worsen only in Japan. Moreover, a higher government income tax revenue uniquely increases the government’s spending that increases the carbon emissions in Malaysia, UAE, Thailand, Indonesia, Turkey, Iran, India, and China, and decrease in Japan. The negative shock of government revenue has adverse results on carbon emissions in these economies. However, short-run asymmetric effects translate to long-run effects in most Asian economies.
Show more [+] Less [-]Reference values for trace essential elements in the whole blood and serum samples of the adult Serbian population: significance of selenium deficiency Full text
2020
Stojsavljević, Aleksandar | Jagodić, Jovana | Vujotić, Ljiljana | Borković-Mitić, Slavica | Rasic-Milutinovic, Z. (Zorica) | Jovanovic, D. (Dragana) | Gavrović-Jankulović, Marija | Manojlović, Dragan
This study was aimed to determine reference values (RVs) for the manganese (Mn), copper (Cu), zinc (Zn), and selenium (Se) in the whole blood (B) and serum (S) samples of the Serbian population. Blood specimens were collected from healthy persons (n = 295; women/men ratio = 149/146; mean age: 42 ± 2 years). The RVs were calculated as lower limit (LL) and upper limit (UL) of the 95% confidence interval (CI) and were expressed as percentiles (P) in the range from P2.5 to P97.5. The influences of sex, age, and smoking habits on element profiles were considered. It was found that the contents of B-Cu and S-Cu were higher in women, while the contents of B-Zn and S-Zn were higher in men. Both trace elements were significantly increased in a group of persons above 40 when compared to a younger persons (≤ 40 years). According to smoking habits, increased content was found only for S-Mn in the nonsmoker’s group (p < 0.05). Comparing our results to the results reported in other population groups worldwide, the Serbian population had significantly reduced content of Se in both types of samples. This finding could highlight the deficiency of Se in the investigated Serbian population and could contribute to the better understanding of the molecular basis for the increased incidence of thyroid and other diseases in which selenium plays a key role.
Show more [+] Less [-]Enhanced arsenic removal from water by a bimetallic material ZrOx-FeOx with high OH density Full text
2020
Vences Álvarez, Esmeralda | Lopez-Valdivieso, Alejandro | Cházaro-Ruíz, Luis F. | Flores-Zuñiga, Horacio | Rangel-Mendez, Jose Rene
Arsenic in groundwater for human consumption has negative effects on human’s health worldwide. Due to the above, it is essential to invest in the development of new materials and more efficient technology for the elimination of such priority contaminants as arsenic. Therefore, in the present work, it was synthesized an amorphous hybrid material ZrOx-FeOx with a high density of OH groups, to improve the arsenic adsorption capacity of iron (FeOx) and zirconium (ZrOx) that makes up the bimetallic oxyhydroxide. The spectra of FT-IR and pKₐ’s distribution suggest that in the synthesized binary oxides, a new union between the two metallic elements is formed by means of an oxygen (metal-O-metal). In addition, TEM profiles suggest that there are chemical interactions between both metals since no individual particles of iron oxide and zirconium oxide were found. According to the results, the adsorption capacity of the ZrOx-FeOx material increases 4.5 and 1.4 times with respect to FeOx and ZrOx, respectively. At pH 6, the maximum adsorption capacity was 27 mg g⁻¹, but at pH greater than 7, the arsenic adsorption capacity onto ZrOx-FeOx decreased 66%. Graphical Abstract
Show more [+] Less [-]The impact of particulate matter 2.5 on the risk of preeclampsia: an updated systematic review and meta-analysis Full text
2020
Yu, Hongbiao | Yin, Yangxue | Zhang, Jiashuo | Zhou, Rong
There is increasing and inconsistent evidence of a linkage between maternal exposure to particulate matter 2.5 (PM2.5) and preeclampsia. Therefore, this study was conducted to investigate this relationship. Electronic databases including PubMed, Embase, Web of Science, and Cochrane Library were searched to identify articles published from inception to March 23, 2020, which showed a correlation between PM2.5 and preeclampsia. Finally, 9 of 523 initial studies were deemed eligible for inclusion. A random effect model was adopted to calculate the standardized odds ratio (OR) and 95% confidence interval (CI). Based on potential effect modification, subgroup analyses were further performed. Meta-analysis showed that maternal exposure to PM2.5 (per 10 μg/m³ increment) elevated the risk of preeclampsia (OR = 1.32, 95% CI 1.10 to 1.58%). Compared with other pregnancy trimesters, the third trimester of pregnancy seems to be the period in which women are more susceptible to PM2.5. Significant effect modification of the correlation between PM2.5 exposure and preeclampsia according to multiple pregnancies, pregnancy stage, maternal-related disease history, and sample size was not observed. The results demonstrated that maternal exposure to PM2.5 may predispose pregnant women to develop preeclampsia, especially in the third trimester of pregnancy. Therefore, more efforts should be made to improve air quality to maintain the health of pregnant women.
Show more [+] Less [-]Climate change and cotton production: an empirical investigation of Pakistan Full text
2020
Abbas, Shujaat
This study investigates the relationship between climate change, the area under cultivation, fertilizer consumption, and cotton production in Pakistan from 1980 to 2018. The existence and nature of the short-term and long-term relationships are explored by using an autoregressive distributed lag (ARDL) model bounds testing approach. The estimated result of the ARDL bounds testing approach has shown the presence of cointegration between dependent and explanatory variables. The long-term estimates have revealed that the increasing average temperature has a positive insignificant effect, which implies that rising temperature is not increasing cotton yield in Pakistan. The findings of the area under cultivation and fertilizer consumption have revealed significant positive effects in both the long run and short run. This study urges Pakistan to reduce the pace of climate changes and increase water conservation by planting forests and constructing dams across major rivers along with the adoption of environmentally friendly production techniques and inputs.
Show more [+] Less [-]Protective potency of ascorbic acid supplementation against cytotoxicity and DNA fragmentation induced by triphenyltin on human liver carcinoma cells Full text
2020
Alkahtane, Abdullah A.
Agrochemicals are one the most significant sources of environmental pollution. Cytotoxicity and genotoxicity are the serious side effects of fungicide. In the current study, I have evaluated acute cytotoxicity and genotoxicity of triphenyltin (TPT) on human hepatic carcinoma (HepG2) cells and the ameliorating effect of ascorbic acid for 24 h. In this experiment, I have exposed HepG2 cells to ascorbic acids (50, 100, and 200 μM) simultaneously and 24 h prior triphenyltin (TPT, 400 ng/ml) exposure for 24 h to determine the protective effect of ascorbic acid by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and NRU (neutral red uptake) assays. Oxidative stress, such as intracellular reactive oxygen species and glutathione levels, was measured in HepG2 cells. The intracellular reactive oxygen species was evaluated using fluorescent probe DCFDA (6-carboxy-2′,7′ dichloro-dihydrofluorescein diacetate). Apoptosis and genotoxicity effects of TPT in HepG2 cells were determined using flow cytometry and comet assay. The result of these experiments showed that the TPT compound (400 ng/ml) induced cytotoxicity, oxidative stress and apoptosis, and DNA damage in HepG2 cells.Ascorbic acid reduced cytotoxicity, oxidative stress, apoptosis, and genotoxicity induced by TPT. Thus, ascorbic acid is a potent antioxidant, and it showed a significant protective effect against toxicity induced by TPT in HepG2 cells.
Show more [+] Less [-]Detection and occurrence of microplastics in the stomach of commercial fish species from a municipal water supply lake in southwestern Nigeria Full text
2020
Adeogun, Aina O. | Ibor, Oju R. | Khan, Essa A. | Chukwuka, Azubuike V. | Omogbemi, Emmanuel D. | Arukwe, Augustine
Microplastics (MPs) are physical anthropogenic pollutants and their ability to act as contaminant vectors in biological matrices is of serious ecosystem and human health concern. In the present study, we have, for the first time, screened and detected MPs in the stomach of a select group of commonly consumed fish species from a municipal water supply lake (Eleyele) in Nigeria. A total of 109 fish samples consisting of eight (8) species: Coptodon zillii (CZ: n = 38), Oreochromis niloticus (ON: n = 43), Sarotheron melanotheron (SM: n = 19), Chrysicthys nigrodigitatus (CN: n = 3), Lates niloticus (LN: n = 3), Paranchanna obscura (PO: n = 1), Hemichromis fasiatus (HF: n = 1), and Hepsetus odoe (HO: n = 1) were collected between February–April, 2018. Fish stomach content was screened for the presence of MPs using the density gradient separation technique (NaCl hypersaline solution) and examined using a fluorescence microscope. MPs were present in all the species screened (except H. fasciatus) with a frequency of 69.7% positive individuals in the examined species. MP prevalence was highest in ON (34%) > CZ (32%) > SM (13%) > CN (6%) and 5% each, for PO HO, and LN. On average, 1–6 MPs with sizes ranging between 124 μm and 1.53 mm were detected per individual. However, the highest number (34) of MPs was detected in the stomach of SM. Principal coordinate analysis (PCA) identified ecological variables such as habitat, feeding mode, and trophic levels as critical factors that may determine and influence MP uptake in fish population. The PCA showed stronger association between fish habitat, feeding mode, and trophic level with MP size and number in the benthopelagic species (ON CZ and SM), compared to demersal species (PO CN HO and LN). Given that MPs can act as vectors for the transfer of pathogens and environmental contaminants (both legacy and emerging), in addition to direct health risks to aquatic organisms, our findings raise concerns on the potential human/wildlife health effects of MPs in these economically and ecologically important food fishes.
Show more [+] Less [-]Clinical features and first degree relative breast cancer, their correlation with histological tumor grade: a 5-year retrospective case study of breast cancer in Mizoram, India Full text
2020
Zodinpuii, Doris | Pautu, Jeremy Lalrinsanga | Zothankima, Bawitlung | Pachuau, Lalawmpuii | Kumar, Nachimuthu Senthil
The aim was to assess the association of histological tumor grade with other clinical features and epidemiological factors of women with invasive breast carcinoma. A retrospective study of 103 Mizo breast cancer patients visiting hospitals was made in Aizawl, Mizoram, Northeast India. With a prior consent, information on epidemiological factors and family history in relation to cancer was obtained. Clinical reports were obtained from their medical records. The frequency of distribution was calculated for age at diagnosis and tumor characteristics. Statistical analysis for different variables was done using a chi-square test. p < 0.05 was considered significant. The histological tumor grades in our studies were found to be associated with lymph node invasion (p < 0.021), different subtype of hormone receptor such as ER status (p < 0.004), ER/PR status (p < 0.007), HER2/neu status (p < 0.014), and ER/PR/HER2 status (p < 0.025). A patient with a family history of breast cancer in their 1st degree relative is also seen to have association in determining the tumor grade (p < 0.003). Reproductive history, lifestyle and dietary habits, tobacco, and alcohol consumption were found to have no influence on breast cancer tumor grade. Our results showing significant correlation between status of lymph node, ER, PR, and HER2/neu oncoprotein and family history with 1st degree relative breast cancer are the first time report to target and focus on the possible role of biomarkers for diagnosis among the Mizo tribal breast cancer patients.
Show more [+] Less [-]Effect of dissolved organic matters and inorganic ions on TiO2 photocatalysis of diclofenac: mechanistic study and degradation pathways Full text
2020
Gao, Ling | Zhou, Beihai | Wang, Fei | Yuan, Rongfang | Chen, Huilun | Han, Xiaomin
Diclofenac (DCF) exists extensively in sewage treatment plant effluent, and it is one of the most reported environmental pharmaceutical contaminants. In this work, the photocatalytic degradation of DCF by titanium dioxide (TiO₂) in pure water under visible light and the influence of humic acids (HA) (as a kind of dissolved organic matter (DOM), phosphate and ferrous ion (Fe²⁺)) were investigated. The results showed that the lower the pH was, the better the degradation effect of DCF under acidic conditions was. Different concentrations of DOM, phosphate ion, and Fe²⁺ could inhibit the degradation of DCF, and the higher the concentration was, the stronger the inhibition was. Different concentrations of chloride ions had little effect on the degradation. A slight elimination (8–12.9%) of total organic carbon (TOC) was observed during the mineralization of DCF with and without DOM and inorganic ions, indicating poor mineralization during the process of photocatalytic degradation, and DOM, phosphate, and Fe²⁺ had little effect on DCF mineralization. Furthermore, hydroxyl radicals, superoxide radicals, and singlet oxygen radicals were present during the photocatalytic degradation of DCF. DOM and inorganic ions could inhibit the intensity of hydroxyl radical and promote superoxide radicals (O₂–) and singlet oxygen (¹O₂) to varying degrees. Finally, the degradation mechanism and main products were analyzed by liquid chromatography–mass spectrometry (LC–MS), and nine possible intermediates were detected. Hydroxylation, dechlorination, cyclization, and oxidation were the main degradation mechanisms. However, DOM, phosphate, and Fe²⁺ did not affect the type of intermediate products in terms of the mass-to-charge ratio. This paper mainly studied the mechanisms of different influencing factors in simulated environments to provide a theoretical basis for the degradation of DCF in wastewater treatment plants. Graphical abstract
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