خيارات البحث
النتائج 5421 - 5430 من 6,489
Household energy choice for domestic cooking: distribution and factors influencing cooking fuel preference in Ouagadougou النص الكامل
2020
Sana, Adama | Kafando, Benoit | Dramaix, Michèle | Meda, Nicolas | Bouland, Catherine
Many studies have highlighted the link between indoor air pollution from the burning of solid fuels for cooking and heating and the occurrence of various health problems particularly in women and children under 5 years. In developing countries, solid fuels remain the main sources of energy. The purpose of this study aims to describe the distribution of household cooking fuel types and to analyze the factors influencing household cooking energy choice in Ouagadougou. A cross-sectional survey was conducted in 2017 in 3 neighborhoods of Ouagadougou. A total of 1734 household were randomly selected. We performed a multivariable logistic regression and a multinomial logistic regression to measure the relationship between selected determinants and households’ primary cooking fuel. 59.53% of the households of Ouagadougou reported using solid fuels as the main cooking fuel. Wood is the most common primary cooking fuel used (43.93%), followed by LPG (40.41%) and then charcoal (15.60%). About 84% combine at least 2 types of energy for cooking. Cooking fuel choice is strongly influenced by the socioeconomic status, the family size, and also by the woman’s educational attainment, her age and the main cooking fuel used in her parents’ house. Actions aimed at reducing the impact of solid fuel use in the environment or health must consider these factors.
اظهر المزيد [+] اقل [-]Ketamine exerts neurotoxic effects on the offspring of pregnant rats via the Wnt/β-catenin pathway النص الكامل
2020
Zhang, Xintong | Zhao, Jinghua | Chang, Tian | Wang, Qi | Liu, Wenhan | Gao, Li
Ketamine is an anesthetic and analgesic drug widely used in clinical anesthesia. To ensure the safety of anesthesia, it is necessary to study its side effects. Pregnancy is a key period for the development and growth of offspring. During this period, the proliferation and differentiation of brain cells and the synaptic formation are easily affected by external stimuli. Therefore, the aim of this study was to evaluate the effect of ketamine. Ketamine anesthesia was administered to rats in the second trimester of pregnancy, and two behavioral tests were performed, including contextual and cued fear conditioning test (CFC) and Morris water maze (MWM). At the end of the behavioral test, Nissl and Golgi staining were used to detect the dendrite density of hippocampal neurons to reveal the effect of maternal ketamine anesthesia on the hippocampus of offspring. Key proteins and their downstream transcription factors in Wnt/β-catenin signaling pathway from the embryonic development to the adulthood were studied. Our results showed that rats receiving maternal ketamine suffered from nerve injury. The density of hippocampal nerves and dendritic spine changed. Some genes related to Wnt/β-catenin pathway and Tcf/Lef were downregulated. In conclusion, maternal anesthesia with ketamine in the second trimester of pregnancy can lead to cognitive memory impairment and neurotoxicity in the hippocampus of offspring through Wnt/ β-catenin signaling pathway.
اظهر المزيد [+] اقل [-]Effects of light color on interspecific competition between Microcystis aeruginosa and Chlorella pyrenoidosa in batch experiment النص الكامل
2020
Tan, Xiao | Zhang, Danfeng | Duan, Zhipeng | Parajuli, Keshab | Hu, Jianyong
In lakes, suspended inorganic particles and dissolved substance are able to absorb or scatter different light wavelengths, leading to the changes of underwater light spectra which are highly related to the water quality. In turn, such changes could form environmental filtering for phytoplankton community to select particular algal populations via intensive competition for light resources. As an example, eutrophic lakes where underwater light spectra changed dramatically have a result of cyanobacterial blooms. In this study, in order to test the effect of light spectrum on growth and competition of green algae and cyanobacteria, Chlorella pyrenoidosa (a common green alga) and Microcystis aeruginosa (a bloom-forming cyanobacterium) grew and competed under three light colors: white (400–700 nm), red (620–700 nm), and blue (410–490 nm) light. Mono- and co-cultured systems were designed and population dynamics of the two species were monitored. The Lotka-Volterra model was used to quantify interspecific competition. Moreover, their photosynthetic activities were measured in mono-cultures. Results showed that in mono-cultures, red light was more favorable for M. aeruginosa, while blue light promoted the growth of C. pyrenoidosa. In co-cultures, M. aeruginosa won in red light and white light, while C. pyrenoidosa dominated under blue light. Light color mainly affected the absorption flux of reaction center (ABS/RC) in photosynthetic system II (PSII) and its potential photosynthetic capacity (Fᵥ/Fₘ). Fᵥ/Fₘ of M. aeruginosa in red light (or C. pyrenoidosa in blue light) was significantly enhanced. This study revealed that light color showed a significant influence on interspecific competition between green algae and cyanobacteria, which offers new insights into the dominance establishment and bloom formation of Microcystis.
اظهر المزيد [+] اقل [-]Bio-reserves inventory—improving substrate management for anaerobic waste treatment in a fast-growing Indian urban city, Chennai النص الكامل
2020
Velusamy, Mozhiarasi | Speier, Christopher Josef | Michealammal, Benish Rose Pious | Shrivastava, Runal | Rajan, Balakumar | Weichgrebe, Dirk | Venkatachalam, Srinivasan Shanmugham
India is one among the Asia’s newly industrialized countries, in which urban centres generate large amount of municipal solid wastes due to the rapid urbanization. To demonstrate urban waste potentials for biogas production by anaerobic digestion, a comprehensive analysis on the availability of organic waste hotspots and its biogas potential for the exemplary case of Chennai, India, was undertaken. The identified hotspots and their biogas potential were plotted with Geographical Information System as thematic maps. The results of biogas potential tests revealed strong variations in the biogas potentials of individual waste streams from 240.2 to 514.2 mLN/g oDM (organic dry matter) with oDM reduction in the range of 36.4–61.5 wt.-%. Major waste generation hotspots were identified from the surveyed urban bio-reserves and the biogas potentials within an effective area of 5 km radius surrounding the hotspot were estimated. It was found that the biogas potential of individual hotspots ranged between 38.0–5938.7 m³/day. Further results revealed that the biogas potential during anaerobic co-digestion, by considering nearby bio-reserves in the effective areas of major hotspots, with and without residential organic waste, ranged between 4110.4–18–106.1 m³/day and 253.2–5969.5 m³/day, originating from 144.0–620.0 tons and 3.1–170.5 tons, respectively. Despite variations in the composition of the wastes, the Carbon/Nitrogen ratio, oDM reduction, biogas production and substrate availability were improved during co-digestion of nearby bio-reserves within the major hotspots, thereby improving the prevailing barriers in substrate management during anaerobic digestion of wastes.
اظهر المزيد [+] اقل [-]Investigating the potential of different jute varieties for phytoremediation of copper-contaminated soil النص الكامل
2020
Saleem, Muhammad Hamzah | Rehman, Muzammal | Kāmrān, Muḥammad | Afzal, Javaria | Noushahi, Hamza Armghan | Liu, Lijun
Copper (Cu), with many documented cases of Cu toxicity in agriculture lands, is becoming an increasingly common issue in and elsewhere in China. However, fibrous crop such as jute is being used as phytoremediation candidate in Cu-contaminated soils due to its huge biomass. A pot experiment was conducted using four different varieties (HT, C-3, GC, and SH) of jute grown in highly Cu-contaminated soil (2221 mg kg⁻¹), collected from Hubei Province, China. Results from this study showed that C-3 and HT were more resistant to Cu stress, while GC and SH had a serious effect due to high concentration of Cu and a significant decrease in growth and biomass. Furthermore, Cu in roots, leaves, stem core, and bast were higher in C-3 and HT compared with GC and SH. Likewise, at post-harvesting stage, maximum Cu concentration from Cu-contaminated soil was extracted by C-3 and HT while small amount was accumulated by GC and SH. The high content of malondialdehyde (MDA) in the leaves of GC and SH indicated that Cu induced oxidative damage while the antioxidative enzyme activities of superoxidase dismutase (SOD) and peroxidase (POD) were increased to scavenge reactive oxygen species (ROS) formed during oxidative stress in the plants. Conclusively, it can be identified that when grown in Cu-contaminated soil, C-3 and HT have greater ability to grow in polluted soils and possible phytoremediation materials to revoke a large amount of Cu.
اظهر المزيد [+] اقل [-]Effect of water quality variation on fish assemblages in an anthropogenically impacted tropical estuary, Colombian Pacific النص الكامل
2020
Duque, Guillermo | Gamboa-García, Diego Esteban | Molina, Andrés | Cogua, Pilar
In tropical estuaries, fish diversity varies spatially and temporally due to behavioral processes such as reproductive migrations, predator avoidance, and foraging, which are affected by water quality. Eutrophication is one of the main factors affecting water quality in estuaries. The objective of this study was to determine variation in fish assemblage explained by fluctuating water quality in the Buenaventura Bay. Fish were captured using artisanal trawl nets during the wet, dry, and transitional seasons at four sampling sites. Additionally, alkalinity; phosphate, nitrite, and nitrate concentrations; dissolved oxygen; pH; temperature; and suspended solids were measured. Multivariate analysis was used to assess the effect of water quality on fish assemblage. In Buenaventura Bay, the assemblage composition of Pseudupeneus grandisquamis, Daector dowi, and Citharichthys gilberti was affected by nitrate concentration. Moreover, large fish biomasses were associated with high nitrite concentration, intermediate salinity, and low dissolved oxygen, suggesting that these estuaries are dominated by species tolerant to poor water quality. Species richness was associated with low nitrate and phosphate concentrations, more suitable water quality indicators, and intermediate temperatures. These results suggest that the deteriorating water quality of estuaries as a result of the anthropogenic impact could increase dominance and decrease richness, resulting in structural changes of fish assemblages.
اظهر المزيد [+] اقل [-]Evaluation of urban comprehensive carrying capacity in the Guangdong–Hong Kong–Macao Greater Bay Area based on regional collaboration النص الكامل
2020
Weng, Hongtao | Kou, Jia | Shao, Qinglong
The Guangdong–Hong Kong–Macao Greater Bay Area (GBA) is the most prominent urban agglomeration in China, with plans for further development. Using the regional collaboration theoretical framework for assessing urban comprehensive carrying capacity (UCC), the improved entropy method is applied to establish an index system based on a social, economic, environment, and transportation perspective to compare UCCs of the GBA’s 11 cities for 2000–2016. Results show that the social subsystem is central to the evaluation system. Cities’ performances vary significantly, with six becoming overloaded in 2016 and the other five remaining loadable. Guangzhou performed best, with a rising UCC; Shenzhen rebounded after a long period of decline; Hong Kong’s capacity rose slightly, with some fluctuation; and Macao performed worse and continues to slide, with no signs of improvement. Overall, the UCC of the urban agglomeration showed a downward trend, with only a few cities continuing to improve. The spatial distribution for UCC was high in the north and low in the south, showing scope for improvement. The study enriches regional collaboration theory and proposes policy implications for GBA development.
اظهر المزيد [+] اقل [-]A critical review on radioactive waste management through biological techniques النص الكامل
2020
Natarajan, Varagunapandiyan | Karunanidhi, Mahalakshmi | Raja, Balamanikandan
Our world is subject to various kinds of pollution and contamination due to rapid growth and development of industrialization. Though, industries are helping to improve the human life style in many ways in day to day life such as power generation to treatment of diseases. At the same time, industries emit the waste which causes major environmental pollution and leads to harmful for all living organism. As the renewable energy sources are depleting, energy/power generation become a major research around the world. Nuclear energy is one of the promising energy to sort out the energy demand, but the problem associated with the nuclear energy is the management and treatment of radioactive waste/emission/effluent since which is more dangerous to all living organism. There is a large scale contamination of radioactive waste associated for the past 60 years of global nuclear activity. It is necessary to pay special attention to the management of radioactive wastes in order to approach pollution-free environment and avoid diseases to living organism through various clean-up strategies. In this review, we discussed the wide ranges of strategies available for radioactive waste management such as physical, chemical, and biological methods. Bioremediation may be the powerful tool for treatment of radioactive wastes. Additionally, discussed on recent advancement have been made in treatment of radioactive waste through microbial transformation as well as phytoremediation which play a major role in disposal of radioactive waste.
اظهر المزيد [+] اقل [-]The concentration of polycyclic aromatic hydrocarbons (PAHs) in the processed meat samples collected from Iran’s market: a probabilistic health risk assessment study النص الكامل
2020
Samiee, Samane | Fakhri, Yadolah | Sadighara, Parisa | Arabameri, Majid | Rezaei, Mohammad | Nabizadeh, Ramin | Shariatifar, Nabi | Mousavi Khaneghah, Amin
The concentration of PAHs among raw and cooked meat products (sausages and burgers), randomly collected from five regions of Tehran, Iran, was investigated by the aid of a gas chromatography-mass spectrometry (GC-MS), and the risk assessment was conducted. The concentration of 16 types of PAHs in sausage and burger samples was found in the range of 8.08 to 29.55 and 10.18 to 29.85 μg/kg, respectively. The concentrations of some PAHs such as anthracene (A) (14.12 μg/kg) and acenaphthylene (Acl) (13.4 μg/kg) were higher than the European Standard (2 μg/kg). Among the meat products with different meat percentages (50, 70, and 90), the highest level of total PAHs was noted in the product containing 90% meat (19.34 μg/kg), while the highest mean level of PAHs was noted in fried meat products (23.31 μg/kg). A positive and significant correlation between cooking method and brand of product with the concentration of PAHs (p-value < 0.05) was noted. Also, no concern regarding the non-carcinogenic risk due to the ingestion of PAHs via consumption of the meat products was demonstrated by the health risk. However, the carcinogenic risk due to the consumption of sausage and burger was at the tolerable (1E−6 to 1E−4) and considerable (> 1E−4) risk levels, respectively. In this regard, further assessments to control and modify the cooking method among the Iranian population were recommended.
اظهر المزيد [+] اقل [-]Sulfadiazine dissipation in acidic tropical soils النص الكامل
2020
Reia, Marina Yasbek | Leal, Rafael Marques Pereira | Tornisielo, Valdemar Luiz | Viana, Douglas Gomes | Regitano, Jussara Borges
Sulfadiazine (SDZ) residues have been detected in manured soils as well as their adjacent water resources, but its behavior is still poorly understood in acidic tropical soils. This research aimed to evaluate sorption, leaching, and biodegradation of ¹⁴C-SDZ in four acidic soils from Brazil, using OECD guidelines. Except for the sand soil (Kd = 2.6 L kg⁻¹), SDZ sorption tended to be higher (Kd > 8.4 L kg⁻¹) and more hysteretic (ΔH >> 1) in acidic soils. When freshly applied, SDZ leaching was low (< 0.11% of applied radioactivity (AR)) and could not always be predicted by Kd values; but leaching was restricted when SDZ was aged for 62 days. SDZ mineralization was low (< 3%) but its dissipation was fast (DT₅₀ < 2.3 days and DT₉₀ < 6.3 days) due to fast initial degradation (an unknown metabolite was immediately formed, likely 4-hydroxysulfadiazine) and mainly to fast formation of non-extractable residues (NER) (> 78% of AR up to 7 days). For certain acidic soils, the abrupt breakdown of the SDZ suggests that degradation should be initially chemical and then followed by enzymatically driven reactions. The fast formation of NERs was attributed mostly to chemical bounding to soil humic substances (Type II-NER), but SDZ sequestration cannot be ruled out (Type I-NER). NERs represent a long-term environmental reservoir of SDZ that may cause deleterious effects on non-target organisms as well as promote antibiotic resistance to soil microbes.
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