Уточнить поиск
Результаты 2891-2900 из 4,937
Maternal exposure to bisphenol A during pregnancy interferes testis development of F1 male mice Полный текст
2019
Wei, Yuanyuan | Han, Chao | Geng, Yumeng | Cui, Yuqing | Bao, Yongzhan | Shi, Wanyu | Zhong, Xiuhui
This study was conducted to investigate the effects of maternal exposure to bisphenol A (BPA) on testis development of F1 male mice. The BPA exposure model of pregnant mice was prepared by intragastric administration of BPA at the doses of 0, 2.5, 5, 10, 20, and 40 mg/kg/day at gestation day (GD) 0.5–17.5. The testis index of the offspring mice was calculated at postnatal day (PND) 21 and PND 56. The results showed that maternal exposure to 20 mg/kg BPA during pregnancy significantly increased the testicular index of F1 males at PND 21, and 40 mg/kg BPA significantly decreased the testicular index of F1 males at PND 56 (P < 0.01). BPA significantly reduced serum testosterone (T) and estradiol (E₂) levels, and improved testicular ERα and ERβ levels in F1 males at both PND 21 and PND 56. BPA exposure also upregulated transcription of testicular Dnmt1 and inhibited the transcription of testicular Dnmt3A and Dnmt3B in F1 mice at PND 21. BPA reduced the transcriptional level of testicular DNA methyltransferase (Dnmt), increased the expression of testicular caspase-7, caspase-9, and bax, and decreased the expression of bcl-2 in F1 mice at PND 56. Consistent with that, BPA improved the apoptosis rate in the testis at PND 56 (P < 0.01 or P < 0.05). Our study indicates that BPA disrupts the secretion of testosterone, estradiol, and estrogen receptors by interfering with the transcription of testicular DNA methyltransferase (Dnmt) in offspring males, which damages testicular tissues and affects the potential reproductive function.
Показать больше [+] Меньше [-]Environmental Kuznets curve revisit in Central Asia: the roles of urbanization and renewable energy Полный текст
2019
Zhang, Shun
Based on the environmental Kuznets curve (EKC) hypothesis, the aim of this paper is to examine the relationships among per capita CO₂ emissions, per capita real GDP, per capita renewable energy consumption, and urbanization in a panel of five Central Asian countries (Kazakhstan, Kyrgyz Republic, Tajikistan, Turkmenistan, and Uzbekistan) from 1992 to 2013. For robustness checking, three estimator techniques reveal no evidence of inverted U-shape EKC consistently. Moreover, renewable energy consumption plays negative impact on emissions, while urbanization plays positive, significantly. The findings of heterogeneous panel causality suggest that there are bidirectional causalities; each other expect no causality from emissions to renewable energy. Finally, some implications, such as developing a small renewable energy project and sustainable urbanization and strengthening in-regional and out-regional cooperation, are given in this region.
Показать больше [+] Меньше [-]Review on China’s wind power policy (1986–2017) Полный текст
2019
Yuan, Liuyan | Xi, Jianchao
As an important renewable energy source, wind power plays a key role in mitigating climate change and has become one of the fastest growing clean energies globally. In China, wind energy development has been a vital component of national energy transformation strategy. Over the years, the Chinese government has introduced a series of policies to promote the development of wind power and also to regulate this emerging industry. Base on examining all the key policy documents on wind power issued by the Chinese government over the last 30 years, we find that China has built up a comprehensive policy system, and summarized the current framework of Chinese wind power policy systematically. Then, we analyze the policy objectives, policy tools, major measures, their results in each development stage, and the characteristics and trends of China’s wind power policies. Finally, we discuss the limitations of the current policy and put forward corresponding suggestions.
Показать больше [+] Меньше [-]The apoptotic effects of bisphenol A exposure on the rat ovary: an experimental study Полный текст
2019
Bilgi, Ahmet | Abalı, Remzi | Bilgi, Pınar Tonbaklar | Şahin, Mustafa | Tunçdemir, Matem | Boran, Ahmet Birtan
Bisphenol A (BPA) is a key endocrine-disrupting chemical (EDC) in the manufacturing industry. It is found in the structure of compounds such as polycarbonate and epoxy in combination with other chemicals. Our objective was to investigate the effect of BPA on rat ovaries. A total of 32 female rats were divided into four equal groups: In group 1 (control), vehicle was administered; in group 2, BPA 50 μg/day was administered intraperitoneally; in group 3, BPA 100 mg/kg/day was administered intraperitoneally; and in group 4, BPA 100 mg/kg/day and vitamin C (50 mg/kg) were administered intraperitoneally, while vitamin E (50 mg/kg) was administered intramuscularly. Thirty days after the treatment, the effects of BPA on the ovaries were evaluated by terminal deoxynucleotidyltransferase [TdT]-mediated dUTP-biotin nick end labeling (TUNEL) assay. There was no difference in the number of apoptotic cells between group 2 and group 4. In addition, there was no significant difference between control group and group 2, 4. However, the number of apoptotic cells per unit area was significantly increased in group 3 compared with all groups (p < 0.01, p < 0.05). In conclusion, this study showed that high doses of BPA (100 mg/kg/day) have a toxic effect on the ovaries. The fact that the number of apoptotic cells in the group administered with high dose of BPA + 50 mg/kg/day vitamin C + 50 mg/kg/day vitamin E was lower than that of the high-dose BPA-administered group shows that these vitamins may have a protective effect.
Показать больше [+] Меньше [-]An innovative approach of urban noise monitoring using cycle in Nagpur, India Полный текст
2019
Laxmi, Vijaya | Dey, Jaydip | Kalawapudi, Komal | Vijay, Ritesh | Kumar, Rakesh
Noise is one of the most significant sources of environmental pollution in metro cities. Traffic noise plays an important role to contribute to ambient noise pollution. Noise pollution monitoring was carried out using sound level meter mounted on the cycle with the help of mould fixed on it. Cycle is a noiseless mode of transport and therefore, it was used for noise monitoring over 700 locations in Nagpur City. Noise levels were recorded at each location for 5 min during peak rush hours of traffic in the morning and in the evening at an interval of 1 s leading to around 300 readings each. Noise indices like Lₑq, L₉₀, L₁₀, Lₘₐₓ and Lₘᵢₙ were calculated for noise level data analysis. TNI was also determined for analysis of traffic noise on intersections of roads. Equivalent noise levels were transferred into the Geographic Information System (GIS) and spatial analysis tool was used to create spatial and strategic noise maps. Based on the maps, it is revealed that noise levels are exceeded all over the city with respect to ambient noise standards. It was experienced that intersections of roads during peak rush time are very noisy due to honking. The study recommends the noise monitoring through cycle-mounted sound level meter since it covers unapproachable sites, more coverage in the city that helps in identifying hotspot area of concern for noise abatement strategies and planning.
Показать больше [+] Меньше [-]On the convergence of per capita carbon dioxide emission: a panel unit root test with sharp and smooth breaks Полный текст
2019
Cai, Yifei | Wu, Yanrui
This study aims to examine the stochastic convergence of per capita carbon dioxide (CO2) emissions in 21 OECD countries and 19 emerging market economies. After approximating both sharp and smooth breaks, the panel unit root tests are performed to test the convergence. The empirical results suggest stochastic convergence for the two groups of countries. However, the results are different when tests for individual countries are conducted separately. Specifically, CO2 emissions of only four OECD countries and four emerging market economies show evidence of convergence if smooth breaks are not considered. With the inclusion of both sharp and smooth breaks, convergence is observed for 11 OECD countries and 10 emerging market economies. These findings may have implications for climate change policy making in selected economies.
Показать больше [+] Меньше [-]Financial development and environment in South Asia: the role of institutional quality Полный текст
2019
Zakaria, Muhammad | Bibi, Samina
The paper investigates the effect of financial development and institutional quality on the environment in South Asia. Other determinants of environmental quality included are economic growth, energy consumption, FDI, trade openness and institutional quality. For empirical analysis, panel data is used for the period 1984 to 2015. The estimated results indicate that Environmental Kuznet Curve (EKC) hypothesis holds in South Asia, i.e., environment first deteriorates with economic development and then it starts improving. Empirical results reveal that 1% increase in economic growth worsens environment by 1.709%. However, further increase in economic growth improves environment by 0.104%. Energy consumption has deteriorating effect on environment. Financial development has degraded the environment in the region, which indicates that South Asian countries have used financial development for capitalization and not to improve technology. The estimated results show that 1% increase in financial development deteriorates environment by 0.147%. FDI, which is a measure of financial openness, has mitigating effect on pollution. In turn, trade openness has worsened the environmental quality in the region. Institutional quality has significant negative effect on carbon emissions. It also has significant negative moderating effects on carbon emissions. The findings show that 1% improvement in institutional quality will decrease pollution by 0.114%. The study suggests that South Asian countries should focus more on technology effect and not on scale effect of financial development.
Показать больше [+] Меньше [-]Effect of fullerol nanoparticles on the transport and release of copper ions in saturated porous media Полный текст
2019
Yuan, Yue | Guo, Panpan | Peng, Xianjia
While the application and discharge of carbon nanomaterials (CNMs) increased rapidly, the research on the environmental safety of CNMs is also increasing. The high dispersity and mobility of modified CNMs in environmental media may have impacts on the environmental behavior of heavy metals. This work mainly studied the effect of fullerol nanoparticles (C₆₀(OH)ₙ) on Cu²⁺ transport, sorption, and release in water-saturated porous media. The results showed that due to the strong adsorption capacity of C₆₀(OH)ₙ for Cu²⁺, the transport of Cu²⁺ could be facilitated. However, with the pre-existence of C₆₀(OH)ₙ in porous media, the transport of Cu²⁺ was also slightly enhanced. In addition, when loaded into the pre-contaminated porous medium, the C₆₀(OH)ₙ also enhanced the release of retained Cu²⁺, which implies a high environmental risk of C₆₀(OH)ₙ.
Показать больше [+] Меньше [-]Non-edible vegetable oil–based feedstocks capable of bio-lubricant production for automotive sector applications—a review Полный текст
2019
Singh, Yashvir | Sharma, Abhishek | Singla, Amneesh
Fossil fuel resource is on the draining stage which leads to an increment in the cost of the petroleum products. Nowadays, research is focused on the development of environment-friendly lubricants which are derivatives of renewable sources. Bio-lubricants based on non-edible oil sources are environmentally friendly because they are non-hazardous and biodegradable and no emission of toxic gases were detected when they are used. This study involves the characterizations and advantages, as well as utilization of inedible plant oil–driven bio-lubricants as an alternative for tribological applications. This report also presents the status of the global lubricant market as well as the potential outlook of the bio-lubricants for their future usage. Non-edible plant oil–driven bio-lubricants bear high viscosity, high lubricity, and high viscosity index which can enhance the equipment service life and deserve the ability to carry the high load and results in a minimum amount of metal traces during combustion while applied to engines. Beside their advantages, some of the disadvantages are also there which can be addressed by the employment of certain additives available according to the applications. The detailed study about the different additives utilized during their use in the internal combustion engine is also described in detail during this study. This study provides a detailed description of the possibilities associated with bio-lubricant based on non-edible oil feedstocks to the automotive sector applications.
Показать больше [+] Меньше [-]Moderating role of financial development in environmental Kuznets: a case study of Malaysia Полный текст
2019
Gill, Abid Rashid | Hassan, Sallahuddin | Haseeb, Muhammad
This research article aims to investigate the moderating role of financial development in Environmental Kuznets Curve (EKC) in the context of Malaysia for the period 1970–2016. As the time series variables are integrated of different order therefore, Auto-Regressive Distributed Lag (ARDL) model has been employed to estimate the long-run equilibrium relationship among the variables. The results indicate that EKC does exist for Malaysia and financial development has negative impact on carbon emission. Moreover, financial development is found to have significant moderating impact on income environment relation. More financial development brings early turning point of the EKC. The results recommend that financial development can be used as one of the policy measures to reduce the environmental cost of economic growth in Malaysia.
Показать больше [+] Меньше [-]