خيارات البحث
النتائج 4231 - 4240 من 6,535
Effects of glyphosate and a commercial formulation Roundup® exposures on maturation of Xenopus laevis oocytes النص الكامل
2020
Slaby, Sylvain | Titran, Pauline | Marchand, Guillaume | Hanotel, Julie | Lescuyer, Arlette | Leprêtre, Alain | Bodart, Jean-François | Marin, Matthieu | Lemiere, Sébastien
Pesticides are often found at high concentrations in small ponds near agricultural field where amphibians are used to live and reproduce. Even if there are many studies on the impacts of phytopharmaceutical active ingredients in amphibian toxicology, only a few are interested in the earlier steps of their life cycle. While their populations are highly threatened with extinction. The aim of this work is to characterize the effects of glyphosate and its commercial formulation Roundup® GT Max on the Xenopus laevis oocyte maturation which is an essential preparation for the laying and the fertilization. Glyphosate is an extensively used herbicide, not only known for its effectiveness but also for its indirect impacts on non-target organisms. Our results showed that exposures to both forms of glyphosate delayed this hormone-dependent process and were responsible for spontaneous maturation. Severe and particular morphogenesis abnormalities of the meiotic spindle were also observed. The MAPK pathway and the MPF did not seem to be affected by exposures. The xenopus oocyte is particularly affected by the exposures and appears as a relevant model for assessing the effects of environmental contamination.
اظهر المزيد [+] اقل [-]Neurological effects of subchronic exposure to dioctyl phthalate (DOP), lead, and arsenic, individual and mixtures, in immature mice النص الكامل
2020
Feng, Weiwei | Wu, Xueshan | Mao, Guanghua | Zhao, Ting | Wang, Wei | Chen, Yao | Zhang, Min | Yang, Liuqing | Wu, Xiangyang
Dioctyl phthalate (DOP) (200, 500, and 1000 mg kg⁻¹ bw, i.g.), Pb (Ac)₂ (50 mg L⁻¹, p.o.), and NaAsO₂ (10 mg L⁻¹, p.o.) were administered individually and as mixtures to weanling male mice for 8 weeks. It was observed that Pb, As, and DOP exposure could significantly inhibit the growth and development of mice. Compared with the Pb, As, and Pb + As groups, the activities of iNOS and TNOS were significantly increased, the levels of AChE and SOD were significantly decreased, and the level of MDA was significantly increased in the Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups. The factorial analysis shows that the iNOS, TNOS, and AChE present synergistic effects on Pb, As, and DOP. A significant increase of escape latency and a significant decrease of original platform quadrant stops were observed between Pb + As + DOP-H and Pb + As groups. The factorial analysis shows that there was a synergistic effect on Pb, As, and DOP. Compared with that of the control group, the expression levels of caspase-3 and Bax expression in Pb + As, DOP-H, Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups were significantly increased in the hippocampus. The expression levels of Bcl-2 expression decreased significantly and the Bax/Bcl-2 ratio increased significantly. Pathological alterations on the hippocampus were found in exposed groups. This result shows that combined exposure of Pb, As, and DOP could induce neurotoxicity, of which possible mechanism is hippocampal neuronal apoptosis. Graphical abstract This study shows that there were three components with eigenvalues greater than 1, which together explained 89.40% of total variance. The first component (PC1) showed high loadings on B-SOD, L-SOD, B-MDA, L-MDA, K-MDA, iNOS, tNOS, and AChE and accounted for 46.55% of the total variance after Varimax rotation. PC2 accounted for 23.81% of the total variance with high loadings on B-As, L-As, K-As, and K-SOD, whereas PC3 showed high loadings on B-Pb, L-Pb, and K-Pb and accounted for 19.04% of the total variance.
اظهر المزيد [+] اقل [-]Evaluation of combined developmental neurological toxicity of di (n-butyl) phthalates and lead using immature mice النص الكامل
2020
Mao, Guanghua | Liu, Hongyang | Ding, Yangyang | Zhang, Weijie | Chen, Hui | Zhao, Ting | Feng, Weiwei | Wu, Xiangyang | Yang, Liuqing
In this study, the immature mice were taken to assess the potential neurological toxicity of lead (Pb) and di (n-butyl) phthalates (DBP) combination exposure. Mouse administration with DBP combination with Pb exhibited longer escape latency and lower average number of crossing of the platform. Pb content in the tissues was increased, especially in the brain, after Pb exposure as compared to those without Pb exposure. The alterations of oxidative damages in tissues (MDA and SOD) and biochemical indicators in the brain (AChE, TNOS, and iNOS) were observed, as well as the synergistic effect of joint exposure. Expressions of apoptosis-related protein (bax/bcl-2 ratio and caspase-3) were significantly increased in the hippocampus, while the bcl-2 was remarkably decreased and no significant differences were observed on the bax. The results suggested that the possible mechanisms for the learning and memory ability impairments were as follows: Firstly, the combination exposure induced the occurrence of lipid peroxidation in the brain, leading to damage to the brain cells. Secondly, it destroyed the normal metabolic balance of ACh, causing nerve damage in mice. Thirdly, it induced apoptosis in mouse hippocampal cells. The overall findings revealed that Pb and DBP co-exposure greatly influenced the developmental nervous system and accompanied with synergistic toxic effect.
اظهر المزيد [+] اقل [-]One academic year laboratory and student breathing zone formaldehyde level, measured by gas-piston hand pump at gross anatomy laboratory, Siriraj Hospital, Thailand النص الكامل
2020
Durongphan, Anuch | Amornmettajit, Nutchaya | Rungruang, Jarun | Nitimanee, Eakkapong | Panichareon, Benjaporn
This study used a formaldehyde detector tube with a gas-piston hand pump to assess ceiling levels of student breathing zone and gross laboratory environment across the 2018 academic year. The room dimension was 28.6 × 55.48 × 5.5 m. It contained 90 cadavers, each placed on a hinged cover table. We measured before and during nine body region dissections. There was a significant difference (p < 0.01) between student exposure and laboratory environment levels. The highest level was student exposure during body wall dissection (2.7 ppm), the first laboratory; students may accidentally enter body cavities. The latter two were in abdominal (1.85 ppm) and lower limb dissections (1.49 ppm). The three highest environment levels were in different regions; spinal cord removal (1.13 ppm), lower limb (0.72 ppm), and thorax (0.71 ppm) dissection. Only the perineum environment level (0.09 ppm) was below the NIOSH ceiling level (0.1 ppm), which may result from the table covers that had been opened for 2 weeks before measurement. This study finding signified the importance of student personal exposure monitoring and encouraged the academic year measurement. Because each laboratory has unique factors, those affect formaldehyde levels; dissection steps, dissection table design, cadaver storage protocol, and heating-ventilation-air conditioning system performance, for instance.
اظهر المزيد [+] اقل [-]Uncovering residents’ behaviors, attitudes, and WTP for recycling e-waste: a case study of Zhuhai city, China النص الكامل
2020
Cai, Kaihan | Song, Qingbin | Peng, Shaohong | Yuan, Wenyi | Liang, Yangyang | Li, Jinhui
China is among the countries facing the most serious pollution effects of e-waste. Many studies have focused on e-waste recycling laws and regulations, recycling technologies, and the pollution situation in China. However, there is a lack of case studies from the perspective of the residents’ attitudes and opinions about e-waste recycling. Based on 474 families surveyed by questionnaire, this study, taking Zhuhai City as one example, investigated residents’ behaviors and attitudes toward e-waste disposal, and their willingness to pay (WTP) for e-waste recycling. A majority (76.4%) of respondents realized that the improper treatment of e-waste would cause serious threats to the environment and human health. Only 38.2% of respondents were willing to pay for e-waste recycling. Most respondents believed that the fee should be borne by government and manufacturers. These results imply that income level and satisfaction with management will promote WTP significantly, whereas the recovery price is a negative influence on the respondents’ WTP. The WTP values were positively correlated with environmental awareness and income at 5% and 10%, respectively. Finally, the estimated average monthly WTP value per household in Zhuhai City is 10.2 RMB ($1.6).
اظهر المزيد [+] اقل [-]On the difficulties of being rigorous in environmental geochemistry studies: some recommendations for designing an impactful paper النص الكامل
2020
Pourret, Olivier | Bollinger, Jean-Claude | van Hullebusch, Eric D.
There have been numerous environmental geochemistry studies using chemical, geological, ecological, and toxicological methods but each of these fields requires more subject specialist rigour than has generally been applied so far. Field-specific terminology has been misused and the resulting interpretations rendered inaccurate. In this paper, we propose a series of suggestions, based on our experience as teachers, researchers, reviewers, and editorial board members, to help authors to avoid pitfalls. Many scientific inaccuracies continue to be unchecked and are repeatedly republished by the scientific community. These recommendations should help our colleagues and editorial board members, as well as reviewers, to avoid the numerous inaccuracies and misconceptions currently in circulation and establish a trend towards greater rigour in scientific writing.
اظهر المزيد [+] اقل [-]Accumulation and distribution of cadmium and lead in 28 oilseed rape cultivars grown in a contaminated field النص الكامل
2020
Cao, Xuerui | Wang, Xiaozi | Tong, Wenbin | Gurajala, Hanumanth Kumar | He, Zhenli | Yang, Xiaoe
Heavy metal pollution in soils has become an important concern for human health. Therefore, it is vital to develop suitable remediation strategies for contaminated soils. Oilseed rape tolerates high concentrations of heavy metals and is a promising candidate for the phytoextraction of cadmium (Cd) and lead (Pb) from metal-contaminated soils. A field experiment was conducted to evaluate 28 oilseed rape cultivars including Brassica napus L. and Brassica juncea L. for their ability to accumulate Cd and Pb. These cultivars were grown in a field co-contaminated with Cd (0.78 mg kg⁻¹) and Pb (330 mg kg⁻¹). The results showed that concentrations in shoots ranged from 1.22 to 3.01 mg kg⁻¹ for Cd and from 10.8 to 29.5 mg kg⁻¹ for Pb. Cadmium and Pb accumulations in shoots could reach 83.4 and 799 μg plant⁻¹, respectively. The majority of translocation factors (TFs) for Cd (> 1.0) were higher than for Pb (≤ 1.0). However, concentrations of Cd and Pb in seeds were much lower, in the range of 0.04 to 0.21 mg kg⁻¹ and 0.04 to 0.51 mg kg⁻¹, respectively. The seed yields of oilseed rape varied from 1238 to 2904 kg ha⁻¹, with a mean value of 2289 kg ha⁻¹. Among the cultivars, three (OS-9, OS-12, and OS-15) were selected as Cd and Pb potential accumulators, with Cd accumulation in shoots being 2.74–3.70 times higher and Pb accumulation in shoots being 3.37–5.23 times higher as compared with the lowest accumulating cultivar. These selected cultivars (B. napus) have application potential for phytoextraction of Cd and Pb from polluted soils without stopping agricultural activities and accompanying food safety issues.
اظهر المزيد [+] اقل [-]A theoretical framework for explaining the determinants of food waste reduction in residential households: a case study of Mashhad, Iran النص الكامل
2020
Heidari, Ava | Mirzaii, Fatemeh | Rahnama, Mahbobeh | Alidoost, Faezeh
Food waste has influenced food security for poor people, food safety, economic development, and the environment. The objective of this paper is to examine the food waste reduction behavior in a sample of Iran households. The study used the Theory of Planned Behavior (TPB) as its conceptual framework and further attempted to extend the TPB by incorporating the addition of new variables (e.g., marketing addiction, the perceived ascription of responsibility, moral attitude, waste-preventing behavior, and socio-demographic characteristics). Data was gathered using a systematic random sampling technique and analyzed with structural equation modeling (SEM). The sample size used in the study was 382. The results revealed that TPB and Extended Theory of Planned Behavior (ETPB) models exhibited a reasonable fit to the data. If key goals are to predict intention to reduce food waste (IRFW), the TPB is preferable due to a smaller quantity of comparison criteria. However, if the key goal is to explain IRFW, the ETPB is preferable due to higher R² compared with others. Besides, the variable “waste-preventing behavior” was the most significant variables influencing the intention to reduce food waste. Socio-demographic characteristics such as age, level of education, and income were found to be statistically significant predictors of intention. Finally, the implication for management and the scope for future research have been discussed.
اظهر المزيد [+] اقل [-]Assessing the impacts of globalization and gender parity on economic growth: empirical evidence from OIC countries النص الكامل
2020
Farooq, Fatima | Yusop, Zulkornain | Chaudhry, Imran Sharif | Iram, Robina
The contemporary debate on globalization and gender equality has a strong impact on economic growth. The present study analyzes the impacts of globalization and gender parity on economic growth in the Organization of Islamic Cooperation (OIC) 47 member countries for the period (1991–2017), using System GMM panel data technique. The results of system GMM have also been empirically estimated by making two groups (viz., low-income and high-income OIC member countries from the World Bank data classification, 2019) to examine the robustness of globalization and gender parity on economic growth. The results reveal that there is a negative impact of globalization on economic growth in the overall sample of OIC countries. When estimated by decomposing low-income countries and high-income countries, globalization has a significantly positive impact on economic growth in the case of high-income OIC countries, whereas globalization slashes GDP in the case of low-income OIC countries. The study finds that there is a positive impact of gender parity (ratio of female to male labor force work participation) on economic growth. Moreover, foreign remittances, government expenditures, capital formation, and human capital are also becoming the causes of a significant increase in economic growth in OIC member countries.
اظهر المزيد [+] اقل [-]Comparison between UVA- and zero-valent iron-activated persulfate processes for degrading propylparaben النص الكامل
2020
Palharim, Priscila H. | Graça, Cátia A. L. | Teixeira, Antonio C. S. C.
Conventional wastewater treatments are not efficient in removing parabens, which may thus end up in surface waters, posing a threat to aquatic biota and human health. As an alternative treatment, persulfate (PS)-driven advanced oxidation technologies have gained growing attention for removing these pollutants. In this study, the degradation of propylparaben (PrP) by UVA- and zero-valent iron (ZVI)-activated persulfate was investigated. The effects of initial PS concentration ([PS]₀) and irradiance or ZVI concentration were explored using the Doehlert experimental design. For the UVA-activated system, the specific PrP degradation rate (k) and percent removal were consistently higher for increasing [PS]₀ and irradiance, varying in the ranges 0.0053–0.0192 min⁻¹ and 37.9–77.3%, respectively. In contrast, extremely fast PrP degradation was achieved through the ZVI/PS process (0.3304 < k < 0.9212 min⁻¹), with removal percentages above 97.5%; in this case, paraben degradation was hindered for a ZVI dosage beyond 40 mg L⁻¹. Regarding toxicity, ECOSAR predictions suggest that the degradation products elucidated by LC-MS/MS are less toxic than PrP toward fish, daphnid, and green algae. In addition, both processes showed to be strongly dependent on the water matrix, being ZVI/PS more impacted for a MBR effluent, although its performance was much better than that exhibited by the UVA-driven process (t₁/₂ of 65.4 and 276.1 min, respectively).
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