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Groundwater contamination sources identification based on kernel extreme learning machine and its effect due to wavelet denoising technique Texto completo
2020
Li, Jiuhui | Lu, Wenxi | Wang, Han | Bai, Yukun | Fan, Yue
Measurements of contaminant concentrations inevitably contain noise because of accidental and systematic errors. However, groundwater contamination sources identification (GCSI) is highly dependent on the data measurements, which directly affect the accuracy of the identification results. Thus, in the present study, the wavelet hierarchical threshold denoising method was employed to denoise concentration measurements and the denoised measurements were then used for GCSI. A 0–1 mixed-integer nonlinear programming optimization model (0–1 MINLP) based on a kernel extreme learning machine (KELM) was applied to identify the location and release history of a contamination source. The results showed the following. (1) The wavelet hierarchical threshold denoising method was not very effective when applied to concentration measurements observed every 2 months (the number of measurements is small and relatively discrete) compared with those obtained every 2 days (the number of measurements is large and relatively continuous). (2) When the concentration measurements containing noise were employed for GCSI, the identifications results were further from the true values when the measurements contained more noise. The approximation of the identification results to the true values improved when the denoised concentration measurements were employed for GCSI. (3) The 0–1 MINLP based on the surrogate KELM model could simultaneously identify the location and release history of contamination sources, as well reducing the computational load and decreasing the calculation time by 96.5% when solving the 0–1 MINLP.
Mostrar más [+] Menos [-]Dengue fever awareness: effect of an educational intervention on nursing students, Tanta, Egypt Texto completo
2020
Aldeib, Abdelaziz F. | Saied, Shimaa M.
Dengue fever (DF) is one of the world’s most important vector-borne illnesses. In 2017, Egypt experienced a dengue outbreak. This study aimed to assess the knowledge and attitudes of nursing students regarding DF and the effectiveness of an education intervention to improve students’ knowledge and attitude. An intervention study was conducted among 4th year nursing students of Tanta Faculty of Nursing using a self-administered predesigned validated questionnaire before and after introducing an educational session. The main DF information sources were formal teaching, social networks, television, and physicians. Less than half of the students (45.5%) had “good” knowledge grade after the intervention compared with only 7.2% in the pre-test. The students’ knowledge and attitude improved after the application of the intervention session. The positive impact of the educational intervention on knowledge and attitude regarding DF and its prevention among the target group revealed the importance of the inclusion of teaching materials about DF into the students’ curricula.
Mostrar más [+] Menos [-]Catalytic wet air oxidation of high BPA concentration over iron-based catalyst supported on orthophosphate Texto completo
2020
Kaissouni, Fatiha | Brahmi, Rachid | Zbair, Mohamed | Lafaye, Gwendoline | El Assal, Zouhair | Pirault-Roy, Laurence | Junior, Jacques Barbier | Elaissi, Abdelkrim | Bensitel, Mohammed | Baalala, Mohammed
The catalytic performance of Fe supported on nickel phosphate (NiP) was evaluated for the removal of bisphenol A (BPA) by catalytic wet air oxidation (CWAO) at 140 °C and 25 bar of pure oxygen pressure. The prepared NiP and Fe/NiP materials were fully characterized by XRD, N₂-physisorption, H₂-TPR, TEM, and ICP analysis. Iron (Fe/NiP) impregnation of NiP support enhanced the BPA removal efficiency from 37.0 to 99.6% when CWAO was performed. This catalyst was highly stable given the operating conditions of acidic medium, high temperature, and high pressure. The Fe/NiP catalyst showed an outstanding catalytic activity for oxidation of BPA, achieving almost complete removal of BPA in 180 min at a concentration of 300 mg/L, using 4 g/L of Fe/NiP. No iron leaching was detected after the CWAO of BPA. The stability of Fe/NiP was performed over three consecutive cycles, noting that BPA conversion was not affected and iron leaching was negligible. Therefore, this catalyst (Fe/NiP) could be considered as an innocuous and effective long-lasting catalyst for the oxidation of harmful organic molecules.
Mostrar más [+] Menos [-]Validation of PM10 and PM2.5 early alert in Bogotá, Colombia, through the modeling software WRF-CHEM Texto completo
2020
Casallas, Alejandro | Celis, Nathalia | Ferro, Camilo | López Barrera, Ellie | Peña, Carlos | Corredor, John | Ballen Segura, Miguel
Air quality data from Bogotá, Colombia, show high levels of particulate matter (PM), which often generate respiratory problems to the population and a high economic cost to the government. Since 2016, air quality in the city of Bogotá has been measured through the Bogota Air Quality Index (IBOCA) which works as an indicator of environmental risk due to air pollution. However, available technological tools in Bogotá are not enough to generate early alerts due to PM₁₀ and PM₂.₅. Currently, alerts are only announced once the measured PM values exceed a certain standard (e.g., 37 μ g/m³), but not with enough anticipation to efficiently protect the population. It is necessary to develop an early air quality alert in Bogotá, in order to provide information that improves risk management protocols in the capital district. The purpose of this investigation is to validate the corrective alert presented on the 14th and 15th of February of 2019, through the WRF-Chem model under different weather conditions, using three different setups of the model to simulate PM₁₀ and PM₂.₅ concentrations during two different climatic seasons and different resolutions. The results of this article generate a validation of two configurations of the model that can be used for the Environmental Secretary of the District (SDA) forecasts in Bogotá, Colombia, in order to contribute to the prediction of pollution events produced by PM₁₀ and PM₂.₅ as a tool for an early alert system (EAS) at least 24 h in advance.
Mostrar más [+] Menos [-]An ultrasound-assisted pressure-regulated solid-phase microextraction setup for fast and sensitive analysis of volatile pollutants in contaminated soil Texto completo
2020
Beiranvand, Mohammad | Ghiasvand, Alireza
Release of analytes from their native matrix and diffusion into the gas phase is the rate-limiting step for the sampling of volatiles in complex solid samples. This limitation is more serious in the solvent-less and solvent-free microextraction sampling strategies. In this research, a three-stage reinforced sampling strategy including high-pressure/sonication/low-pressure was introduced for fast and efficient release of analytes in soil samples. For this purpose, a novel ultrasound-assisted pressure-regulated solid-phase microextraction (UA-PR-SPME) device was developed. It was coupled with gas chromatography-flame ionization detection (GC-FID) and carried out for the determination of benzene, toluene, ethylbenzene, and xylenes (BTEX, as the model analytes) in complex solid samples. Graphene oxide/3-aminopropyltriethoxysilane (GO-APTES) nanocomposite was synthesized and used as the SPME fiber coating. Under optimal conditions, the limits of detection (LODs) were obtained 0.1–0.4 ng/g. The calibration curves were linear over the range of 2.4–5000 ng/g. Relative standard deviations (RSDs%) were calculated 5.1–7.0% (n = 6). The developed technique was employed for the analysis of BTEX in contaminated soil samples.
Mostrar más [+] Menos [-]Synthesis of carbon nanotubes via chemical vapor deposition: an advanced application in the Management of Electroplating Effluent Texto completo
2020
Verma, Bharti | Sewani, Hitesh | Balomajumder, Chandrajit
Iron catalyst supported over magnesium oxide had been synthesized with different percentages of Fe, i.e., 0.5, 1, and 5% employing the method of impregnation. These fabricated catalysts were used to grow carbon nanotubes (CNTs) using a chemical vapor deposition (CVD) method in the CVD reactor. The 5% Fe/MgO catalyst showed the maximum growth of CNTs. The synthesized novel CNTs (5Fe-CNTs) were investigated for their adsorption capabilities for the removal of parts per million levels of hexavalent chromium from electroplating effluent. The 5Fe-CNTs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and Zeta analyzer. The 5Fe-CNTs showed remarkable adsorption capacity of 63.3 mg g⁻¹ toward Cr(VI) in water. The effects of various operating conditions on the removal of Cr(VI) from wastewater have been evaluated. Kinetic and thermodynamic studies were performed, and it was observed that the experimental data is in best agreement with pseudo-second-order kinetics. Besides the synthesized CNTs exhibited good recyclability for adsorbing Cr(VI) as even after 3 adsorption cycles, the adsorption capacity was reduced by less than 10%.
Mostrar más [+] Menos [-]The enhancement of NH3-SCR performance for CeO2 catalyst by CO pretreatment Texto completo
2020
Zhang, Ping | Guo, Rui-tang | Wu, Li-jun | Pan, Wei-guo
CO pretreatment was found to effectively improve the SCR performance of CeO₂, with over 90% at about 300 °C. The larger specific area and the decrease of CeO₂ crystallization indicated the modification of the surface structure after CO pretreatment. Abundant Ce³⁺ species and active oxygen, better reducibility, and the higher surface adsorption capacity were mainly responsible for its enhanced SCR performance. DRIFT analysis revealed the presumed coexistence of two reaction routes that the L-H mechanism was related to the reaction temperature, while the reaction rate of E-R route was almost directly proportional to the NO concentration at a certain temperature, based on the kinetic calculation. In addition, the CO-pretreated CeO₂ also exhibited a better poisoning tolerance for SO₂ and H₂O and excellent thermal stability and circularity. Graphical abstract The process of NH₃-SCR reaction over CeO₂-CO catalyst.
Mostrar más [+] Menos [-]On the asymmetric effects of premature deindustrialization on CO2 emissions: evidence from Pakistan Texto completo
2020
Ullah, Sana | Ozturk, Ilhan | Usman, Ahmed | Majeed, Muhammad Tariq | Akhtar, Parveen
In this modern era, environmental pollution is the biggest problem attached to industrialization. This study tries to ensure the relationship between industrialization and CO2 emissions in Pakistan for the time period 1980–2018 by using nonlinear ARDL model while controlling for urbanization, GDP, and human capital variables as a likely factor of CO2 emissions. Our foremost study objective is to examine whether or not the outcome of industrialization on CO2 emissions is symmetric or asymmetric for Pakistan that is one of the core suppliers to CO2 in South Asia, as the emissions were 0.82 million tons in 2018. Our result approves the presence of an asymmetric effect of industrialization shocks on CO2 emissions both in the short run and long run. The results reveal that industrialization increases emissions and deindustrialization decrease emissions, in short as well as long run, in Pakistan. Moreover, our finding also advises that urbanization and GDP variables have exerted a positive impact on CO2 emissions. Based on the findings, some policy suggestions are proposed for Pakistan.
Mostrar más [+] Menos [-]Symbiont-bearing foraminifera as health proxy in coral reefs in the equatorial margin of Brazil Texto completo
2020
Eichler, Patrícia P. B. | de Moura, Diogo S.
Coral communities worldwide are progressively more stressed by anthropogenic activities that increase fluxes of sediment and other pollutants to nearshore areas. Some nearshore coral reef environments off the Equatorial margin of Brazil, including Pirangi and Maracajaú, Rio Grande do Norte (RN, Brazil), seem to be under human-induced stress. However, the horizontal extent of this stress, its effects, and assessment of the environmental response depend on the hydrodynamic conditions (circulation and deposition patterns), sedimentary facies, and the availability of biological indicators. We investigate two Brazilian live reefal corals’ communities by examining seven photosymbiont-bearing species (PSB) of Foraminifera, Amphisorus hemprichii, Amphistegina gibbosa, Archaias angulatus, Borelis schlumbergeri, Heterostegina antillarum, Peneroplis carinatus, and Laevipeneroplis proteus, using numerical analysis FORAM Index (FI), grain size, and particulate organic and inorganic carbonate. Here, we show that coarse sand fraction followed by fine sand fraction and high hydrodynamics plays an important role in transportation and deposition of sediments and foraminiferal tests in the study area. According to FI results, conditions at Pirangi are not suitable for coral reef growth. Maracajaú has sites that are suitable for coral reef growth and sites where coral could not survive after a stress event. We need long-term assessments to improve our knowledge of the distribution and ecological importance of Brazilian reef-dwelling foraminifers and to extend the application of FI to monitoring management plans of the Pirangi and Maracajaú National Marine Parks by providing a first insight into the biodiversity patterns and a reliable tool of the reconstruction of paleo reef health.
Mostrar más [+] Menos [-]Tertiary treatment of coke plant effluent by indigenous material from an integrated steel plant: a sustainable approach Texto completo
2020
Das, Suprotim | Biswas, Pinakpani | Sarkar, Supriya
Biological process is an important and integral part of the coke plant wastewater treatment. Increasing pressure to meet more stringent discharge limits has led to adopt tertiary treatment for biologically treated coke plant (BTCP) effluent which contains intense colour along with many residual toxic pollutants like phenol, cyanide, thio-cyanate and COD. A sustainable process has been developed to remove these pollutants from BTCP effluent by using an indigenous material coke breeze which is abundantly available in integrated steel plant. Based on the developed process, a full-scale (200 m³/h) treatment plant has been designed for installation. The designed data has been obtained from a continuous demo plant treating 10 m³/h BTCP effluents. The utilised coke breeze is entirely used for sinter making. The process is highly efficient for the removal of colour above 95% and other residual pollutants like phenol, cyanide and COD to a safe level for discharge or reuse. This process neither incurs any additional chemical cost nor generates any secondary pollutants or products. Moreover, the developed process is very sustainable as it has some great advantages like less investment and low maintenance cost; therefore, the method is good in economics. The treated wastewater contains very less amount of chemical residues therefore meets the standards for reuse as industrial water resource. Hence, this developed technology has significant economic, social and environmental benefits. Graphical Abstract .
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