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Resultados 2711-2720 de 4,896
The effect of temperature on airborne filamentous fungi in the indoor and outdoor space of a hospital
2019
Abbasi, Fariba | Samaei, Mohammad Reza
Fungi are one of the bioaerosols in indoor air of hospitals. They have adverse effects on staff and patients. The aim of this study was to investigate the effects of three incubation temperature on the density and composition of airborne fungi in an indoor and outdoor space of hospital. Sabouraud dextrose agar was used for culture the fungi. For improvement of aseptic properties, chloramphenicol was added to this medium. The density of airborne fungi was less than 282 CFU/m³. The highest density was detected in emergency room and the lowest of them was in neonatal intensive care unit (NICU) and operation room (OR). Results showed that fungi levels at 25 °C were higher than 37 and 15 °C (p = 0.006). In addition, ten different genera of fungi were identified in all departments. The predominant fungi were Fusarium spp., Penicillium spp., Paecilomyces spp., and Aspergillus niger. Moreover, the density and trend of distribution of Fusaruim spp. in the indoor space was directivity to outdoor space by ventilation system. The present study has provided that incubation temperature had effect on airborne fungi remarkably. We are suggested that more studies would be conducted on incubation temperature and other ambient factors on airborne fungi.
Mostrar más [+] Menos [-]Effect of Activation Time on the Performance and Mechanism of CO2-Activated Wheat Straw Char for the Removal of Cd2+
2019
Li, Mengxue | Shu, Daobing | Liu, Haibo | Chen, Tianhu | Chen, Dong
The removal behavior and characteristic of cadmium (Cd²⁺) on wheat straw char activated by CO₂ were investigated in this study. The equilibrium, kinetics, and removal isotherms were studied. The results of batch experiments revealed that the removal of Cd²⁺ was described well by pseudo-second-order and Langmuir models. The increase in activation time improved the removal of Cd²⁺, especially for the activation time of 84 min. The results suggested that chemisorption of Cd²⁺ on activated carbon was the main reaction mechanism. The maximum removal capacity of Cd²⁺ onto activated WSC-84 was 75.55 mg/g, which was much higher than other three samples activated by CO₂ with other amounts of time. According to the results of SEM, XPS, and FT-IR, complexation with surface oxygen-containing functional groups, ion exchange, and precipitation were the possible mechanisms of the removal process. It is suggested that the experimental results will enhance the comprehensive understanding of the activation of biomass and its utilization in the restoration of Cd-contaminated soil.
Mostrar más [+] Menos [-]Vertical variation of bulk and metabolically active prokaryotic community in sediment of a hypereutrophic freshwater lake
2019
Tsuboi, Shun | Kohzu, Ayato | Imai, Akio | Iwasaki, Kazuhiro | Yamamura, Shigeki
This study was conducted to acquire novel insight into differences between bulk (16S rDNA) and metabolically active (16S rRNA) prokaryotic communities in the sediment of a hypereutrophic lake (Japan). In the bulk communities, the class Deltaproteobacteria and the order Methanomicrobiales were dominant among bacteria and methanogens. In the metabolically active communities, the class Alphaproteobacteria and the order Methanomicrobiales and the family Methanosaetaceae were frequently found among bacteria and methanogens. Unlike the bulk communities of prokaryotes, the composition of the metabolically active communities varied remarkably vertically, and their diversities greatly decreased in the lower 20 cm of sediment. The metabolically active prokaryotic community in the sediment core was divided into three sections based on their similarity: 0–6 cm (section 1), 9–18 cm (section 2), and 21–42 cm (section 3). This sectional distribution was consistent with the vertical pattern of the sedimentary stable carbon and nitrogen isotope ratios and oxidation–reduction potential in the porewater. These results suggest that vertical disturbance of the sediment may influence the communities and functions of metabolically active prokaryotes in freshwater lake sediments. Overall, our results indicate that rRNA analysis may be more effective than rDNA analysis for evaluation of relationships between actual microbial processes and material cycling in lake sediments.
Mostrar más [+] Menos [-]The Effect of Temperature Oscillations and Sediment Texture on Fecal Indicator Bacteria Survival in Sediments
2019
Smith, Jaclyn E. | Stocker, Matthew D. | Hill, Robert L. | Pachepsky, Y. (Yakov)
Fecal indicator bacteria (FIB) inhabiting stream sediments have become a concern with regard to recreational and irrigation water quality. Sediments contain higher concentrations of E. coli and other FIB than the overlying water column. The objective of this work was to evaluate the effect of temperature oscillations on the populations of both E. coli and enterococci in sediments and the water column. The study was conducted in a microcosm system with flow-through chambers representing a small stream with two different sediment textures. Bovine manure was freshly collected and mixed with both clayey and sandy sediment. Temperatures within the chambers oscillated from 17° to 28 °C which is representative of a diurnal summer temperature range for Maryland; the control chambers were kept at 22 °C. The effect of temperature oscillations differed depending on the sediment texture. Bacterial populations in the sandy sediment immediately increased before net die-off began. Conversely, in the chambers with the clayey sediments, there was no immediate increase in concentrations in the oscillation chambers as compared to the controls. There were significantly higher populations of both E. coli and enterococci within the oscillation sandy texture chambers compared to the control constant temperature chambers; that was not the case in the clayey sediment chambers. The die-off rates in the sandy sediments were greater than those in the clayey sediments; in the latter, bacteria populations remained almost constant throughout the experiment. Temperature oscillations should be simulated in experiments designed to estimate and compare inactivation rates for fecal indicator bacteria in sediments for future inferences on microbial water quality.
Mostrar más [+] Menos [-]Overexpression of AtAAP1 increased the uptake of an alanine-chlorantraniliprole conjugate in Arabidopsis thaliana
2019
Ren, Zhanfu | Chen, Zhiting | Luo, Xiao | Su, Jiebing | Yao, Guangkai | Xu, Hanhong | Lin, Fei
Transporters play an important role in the uptake and redistribution of agrochemicals to the site of insect feeding. The product of the Arabidopsis thaliana gene AtAAP1 substantially contributes to inorganic nitrogen acquisition under ecologically relevant amino acid concentrations. Here, the transporter ability of AtAAP1 to a chlorantraniliprole-alanine conjugate (CAP-Ala-1) was tested both in planta and in vitro. Thirty-day-old and 15-day-old plants overexpressing AtAAP1 increased the uptake of CAP-Ala-1 into the roots, whereas AtAAP1 deficiency did not completely block the uptake of CAP-Ala-1. An uptake experiment carried out in Xenopus laevis oocytes expressing AtAAP1 showed that CAP-Ala-1 interacted with AtAAP1. Although little native AtAAP1 transcription was present in the leaves, constitutive expression of AtAAP1 in plants significantly increased the ability of the leaf mesophyll protoplasts to take up CAP-Ala-1. The observations supported the possibility of exploiting AtAAP1 as a component of a novel delivery and redistribution system for amino acid-based pesticide conjugates.
Mostrar más [+] Menos [-]Recycling of the scrap LCD panels by converting into the InBO3 nanostructure product
2019
Assefi, Mohammad | Maroufi, Samane | Sahajwalla, Veena
Preparation of the value-added products from e-waste resources is an important step in the recycling process. The present paper aims to propose a methodology for the recovery of In from scrap LCD panel via preparation of InBO₃ nanostructure. Discarded LCD panel was subjected to a recycling process through crushing, milling, and oxalic acid leaching to prepare In₂(C₂O₄)₃·6H₂O. Through the leaching process, B(OH)₃ from glass part (alumina borosilicate) has been leached out along with indium oxalate hydrated. Further thermal treatment on these extracted materials at 600 °C could result in the formation of InBO₃ nanostructures with an average particle size of 20 nm. A multistep mechanism based on thermodynamic calculations for the recycling of the InBO₃ form extracted precursors was proposed. Graphical abstract
Mostrar más [+] Menos [-]Catalytic degradation of organic pollutants in Fe(III)/peroxymonosulfate (PMS) system: performance, influencing factors, and pathway
2019
Latif, Abdul | Kai, Sun | Si, Youbin
This study demonstrated, for the first time, Fe(III)/peroximonosulphate (PMS) could be an efficient advanced oxidation process (AOP) for wastewater treatment. Bisphenol A (BPA) was chosen as a model pollutant in the present study. Fe(III)-activated PMS system proved very effective to eliminate 92.18% of BPA (20 mg/L) for 30-min reaction time at 0.50 mM PMS, 1.5 g/L Fe(III), pH 7.0. The maximum degradation of BPA occurred at neutral pH, while it was suppressed at both strongly acidic and alkaline conditions. Organic and inorganic ions can interfere with system efficiency either positively or negatively, so their interaction was thoroughly investigated. Furthermore, the presence of organic acids also affected BPA degradation rate, especially the addition of 10 mM citric acid decreased the degradation rate from 92.18 to 66.08%. Radical scavenging experiments showed that SO₄•– was the dominant reactive species in Fe(III)/PMS system. A total of 5 BPA intermediates were found by using LC/MS. A possible degradation pathway was proposed which underwent through bridge cleavage and hydroxylation processes. Acute toxicity of the BPA degradation products was assessed using Escherichia coli growth inhibition test. These findings proved to be promising and economical to deal with wastewater using iron mineral for the elimination of organic pollutants. Graphical abstract
Mostrar más [+] Menos [-]Evaluation of the environmental noise problems in holiday villages: a case study from Antalya, Turkey
2019
Gürsoy, Özge | Yüğrük Akdağ, Neşe
Not only the appeal of the sun, natural, and historical beauties but also architectural features and business advantages of the accommodation facilities emerge as important factors in tourism development. Holiday villages differ from other types of accommodation facilities in terms of their functions and services. It is important to provide tourists acceptable levels of comfort in holiday villages offering various functions. One of these comfort conditions is acoustic comfort, which involves noise control. Noise emitted from various indoor and outdoor facilities is the main component impacting acoustic comfort in holiday villages. In this study, a holiday village in Antalya, Turkey with an open area of 120,000 m² was examined to identify noise exposure conditions of outdoor areas. Pools, restaurants, animation areas, playgrounds, and courts are the main outdoor noise sources in this holiday village. The noise emitted by these sources during daytime (Ld) and evening time (Le) are shown in noise maps. The open areas affected by 65 LAₑq noise level extend to an area of 55,500 and 21,000 m² during Ld and Le, respectively. With the noise barriers around the main noise sources, impacted open areas are reduced by 13% in Ld and 12% in Le. The results of this study clearly reveals the importance of resolving the issue of environmental noise in the most efficient and cost-effective way in terms of settlement and planning, especially in areas with dominant noise sources like holiday villages.
Mostrar más [+] Menos [-]Optimal path for controlling pollution emissions in the Chinese electric power industry considering technological heterogeneity
2019
Yu, Xianyu | Jin, Lei | Wang, Qunwei | Zhou, Dequn
The electric power industry is not only an important part in the Chinese economic system but also the key industry with the highest emissions of air pollutants in China. This paper aims to control the pollution emissions of the Chinese electric power industry and enhance its electric-generation capacity though pollution-emission allocation patterns and inefficiency elimination. The data envelopment analysis centralized allocation model (DEA-CA) under metafrontier framework is adopted to distribute pollution emissions and electric-generation capacity considering technological heterogeneity at regional and national levels. The empirical result shows that the emission reduction responsibility is directly proportional to regional power generation performance. The metafrontier framework allocates emission permits to combine the national and regional, which makes the adjustment of each province more reasonable. At last, the relationship between the aggregate optimal electricity capacity and the pollution emission control coefficient is shown to follow an inverted U-shape curve, which implies that a modest emission control policy might be more appropriate for the electric power industry to achieve the joint optimizing goal of electricity generation enhancement and pollution emission control.
Mostrar más [+] Menos [-]Assessing the solar PV power project site selection in Pakistan: based on AHP-fuzzy VIKOR approach
2019
Solangi, Yasir Ahmed | Shah, Syed Ahsan Ali | Zameer, Hashim | Ikram, Muhammad | Saracoglu, Burak Omer
Pakistan has an abundant solar power potential which can be effectively utilized for the electricity generation. There are various sites across the country which have sufficient solar irradiation across the year, and thus, suitable for the installation of solar photovoltaic (PV) power projects. This study, therefore, aims to undertake research on the establishment of solar power project site selection in Pakistan. In this context, 14 promising cities of Pakistan are considered as alternatives and studied in terms of economic, environmental, social, location, climate, and orography criteria and further supplemented with 20 sub-criteria. Initially, the analytical hierarchy process (AHP) method has been used to prioritize each of the main criteria and sub-criteria. Later, fuzzy VlseKriterijuska Optimizacija I Komoromisno Resenje (F-VIKOR) method has been employed to prioritize the 14 alternatives. The present investigation reveals that Khuzdar (C2), Badin (C3), and Mastung (C7) are the most suitable cities for the installation of solar PV power projects in Pakistan. Finally, the outcome of the sensitivity analysis revealed that obtained results are reliable and robust for the installation of solar PV power projects in Pakistan. This study shall assist government, energy planners, and policymakers in making cities sustainable by establishing solar power projects in Pakistan.
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