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Sulfur concrete made with waste marble and slag powders: 100% recycled and waterless concrete 全文
2022
Rasheed, Muhammad Faisal | Rahim, Abdur | Irfan-ul-Hassan, Muhammad | Ali, Babar | Ali, Nazam
In this research, the mechanical properties and durability of sulfur concrete with two different waste aggregates were evaluated. The waste aggregates included ground granulated blast-furnace slag and waste marble powder. The properties of sulfur concrete were also compared with those of the conventional binder concretes (i.e., Portland cement concrete and sulfate-resistant cement concrete). The durability parameters included measuring water absorption capacity and resistance to different harsh chemical environments (5% HCl solution, 5 Molar NaOH solution, and 16% NaCl solution). It was found that sulfur concrete made with slag as aggregate exhibited the maximum strength, i.e., about 2 times higher than that of Portland cement concrete and sulfate-resistant cement concrete. Sulfur concrete made with slag and marble waste powder showed superior mechanical performance compared to that made with river sand. Thus, sulfur binder develops more favorable properties with eco-friendly fillers than it develops with natural sand. In harsh chloride and acidic environment, sulfur concrete with slag powder exhibited about 90–95% lesser mass loss than Portland cement concrete.
显示更多 [+] 显示较少 [-]Life cycle environmental impacts of disposable medical masks 全文
2022
Atılgan Türkmen, Burçin
A massive increase in the use and production of masks worldwide has been seen in the current COVID-19 pandemic, which has contributed to reducing the transmission of the virus globally. This paper aims to evaluate the life cycle environmental impacts of disposable medical masks to identify the life cycle stages that cause the highest impact on the environment. A further goal is to estimate the total environmental impacts at the global level in 2020. The inventory data was constructed directly from the industry. The system boundary of the study is from cradle to grave comprising raw material extraction and processing, production, packaging, distribution, use, and disposal as well as transport and waste management along the supply chain. Eleven environmental impacts have been estimated. The results suggest that the global warming potential of a disposable medical mask is 0.02 g CO₂-eq. for which the main contributor is the raw material supply (40.5%) followed by the packaging (30.0%) and production (15.5%). Sensitivity analysis was carried out to test the environmental impacts. In total, 52 billion disposable medical masks used worldwide consumes 22 TJ of energy in 2020. The global warming potential of disposable medical masks supplied in a year of the COVID-19 pandemic is 1.1 Mt CO₂ eq. This paper assessed the hotspots in the medical mask. The findings of this study will be of interest to policymakers, global mask manufacturers, and users, allowing them to make more informed decisions about the medical mask industry.
显示更多 [+] 显示较少 [-]Modern and traditional renewable energy sources and CO2 emissions in emerging countries 全文
2022
You, Vithyea | Kakinaka, Makoto
Sustainable development goals aim to promote the implementation of environmental and energy policies towards establishing a sustainable environment. Considering that energy demand has steadily increased in emerging countries along with their rapid economic growth, controlling CO₂ emissions in these countries is crucial to achieving global environmental sustainability. An important concern is that renewable energy is generally classified into traditional and modern sources, and their relationships with environmental degradation can differ at the macroeconomic level. This study examines the link of the two renewable energy sources to CO₂ emissions by employing an autoregressive distributed lag (ARDL) model for 31 emerging countries from 1990 to 2016. This analysis provides clear evidence of heterogeneity of the effects between traditional and modern renewable energy sources. Although CO₂ emissions have negative associations with both traditional and modern renewable energy sources in the long-term, they are more sensitive to modern renewable energy sources than to traditional ones. These results suggest that modern renewable energy sources are an effective target for environmental and energy policies in emerging countries. Policy regulators and international communities should strengthen domestic and international schemes that facilitate the transfer of green technology, particularly, that related to modern renewable energy sources, from advanced countries to emerging countries.
显示更多 [+] 显示较少 [-]Hydrogen peroxide–assisted photocatalytic dye degradation over reduced graphene oxide integrated ZnCr2O4 nanoparticles 全文
2022
Tantubay, Kartik | Das, Piu | Baskey (Sen), Moni
Zinc chromite nanoparticles (NPs) and zinc chromite–reduced graphene oxide (ZnCr₂O₄-rGO) nanocomposite have been synthesized by the combined effects of reflux condensation and calcination processes. The structural properties were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible studies, etc. Structural morphology was investigated by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) that indicate the formation of particles in the nanometer regime. The presence of the elements Zn, Cr, O and C has been confirmed by energy-dispersive X-ray spectroscopy (EDX) images which show the purity of the synthesized products. The photocatalytic activities of both as-prepared samples under visible light irradiation were investigated in presence of hydrogen peroxide (H₂O₂) and the results show that ZnCr₂O₄-rGO nanocomposite has a quite higher photo-activity response than virgin ZnCr₂O₄ NPs. The enhanced photo response indicates that, in ZnCr₂O₄, the photo-induced electrons favor to transfer to the rGO surface and the recombination of electron–hole pairs inhibited for which it results in the significantly increased photocatalytic activity for the ZnCr₂O₄-rGO photocatalyst and this phenomenon is also supported by the band gap value and photoluminescence results. Our outcomes demonstrate that ZnCr₂O₄-rGO nanocomposite is a more promising material to build up an efficient photocatalyst for waste water treatment.
显示更多 [+] 显示较少 [-]Distribution of ETBE-degrading microorganisms and functional capability in groundwater, and implications for characterising aquifer ETBE biodegradation potential 全文
2022
Nicholls, Henry C. G. | Rolfe, Stephen A. | Mallinson, Helen E. H. | Hjort, Markus | Spence, Michael J. | Bonte, Matthijs | Thornton, Steven F.
Microbes in aquifers are present suspended in groundwater or attached to the aquifer sediment. Groundwater is often sampled at gasoline ether oxygenate (GEO)-impacted sites to assess the potential biodegradation of organic constituents. However, the distribution of GEO-degrading microorganisms between the groundwater and aquifer sediment must be understood to interpret this potential. In this study, the distribution of ethyl tert-butyl ether (ETBE)-degrading organisms and ETBE biodegradation potential was investigated in laboratory microcosm studies and mixed groundwater-aquifer sediment samples obtained from pumped monitoring wells at ETBE-impacted sites. ETBE biodegradation potential (as determined by quantification of the ethB gene) was detected predominantly in the attached microbial communities and was below detection limit in the groundwater communities. The copy number of ethB genes varied with borehole purge volume at the field sites. Members of the Comamonadaceae and Gammaproteobacteria families were identified as responders for ETBE biodegradation. However, the detection of the ethB gene is a more appropriate function-based indicator of ETBE biodegradation potential than taxonomic analysis of the microbial community. The study shows that a mixed groundwater-aquifer sediment (slurry) sample collected from monitoring wells after minimal purging can be used to assess the aquifer ETBE biodegradation potential at ETBE-release sites using this function-based concept.
显示更多 [+] 显示较少 [-]Metronidazole enhances steatosis-related early-stage hepatocarcinogenesis in high fat diet-fed rats through DNA double-strand breaks and modulation of autophagy 全文
2022
Eguchi, Ayumi | Mizukami, Sayaka | Nakamura, Misato | Masuda, Sousuke | Murayama, Hirotada | Kawashima, Masashi | Inohana, Mari | Nagahara, Rei | Kobayashi, Mio | Yamashita, Risako | Uomoto, Suzuka | Makino, Emi | Ohtsuka, Ryoichi | Takahashi, Naofumi | Hayashi, Shim-Mo | Maronpot, Robert R. | Shibutani, Makoto | Yoshida, Toshinori
Nonalcoholic fatty liver disease is a hepatic disorder with deposition of fat droplets and has a high risk of progression to steatosis-related hepatitis and irreversible hepatic cancer. Metronidazole (MNZ) is an antiprotozoal and antimicrobial agent widely used to treat patients infected with anaerobic bacteria and intestinal parasites; however, MNZ has also been shown to induce liver tumors in rodents. To investigate the effects of MNZ on steatosis-related early-stage hepatocarcinogenesis, male rats treated with N-nitrosodiethylamine following 2/3 hepatectomy at week 3 were received a control basal diet, high fat diet (HFD), or HFD containing 0.5% MNZ. The HFD induced obesity and steatosis in the liver, accompanied by altered expression of Pparg and Fasn, genes related to lipid metabolism. MNZ increased nuclear translocation of lipid metabolism-related transcription factor peroxisome proliferator-activated receptor gamma in hepatocytes, together with altered liver expression of lipid metabolism genes (Srebf1, Srebf2, Pnpla2). Furthermore, MNZ significantly increased the number of preneoplastic liver foci, accompanied by DNA double-strand breaks and late-stage autophagy inhibition, as reflected by increased levels of γ-H2AX, LC3, and p62. Therefore, MNZ could induce steatosis-related hepatocarcinogenesis by inducing DNA double-strand breaks and modulating autophagy in HFD-fed rats.
显示更多 [+] 显示较少 [-]Effects of phosphorus-containing material application on soil cadmium bioavailability: a meta-analysis 全文
2022
Tan, Yi | Zhou, Xue | Peng, Yutao | Zheng, Zijing | Gao, Xing | Ma, Yan | Chen, Shuo | Cui, Shihao | Fan, Beibei | Chen, Qing
Diverse phosphorus-containing materials (PCMs) were widely applied in remediation of cadmium-contaminated soils, and their effects on the change of soil cadmium availability (SCA) varied with their physicochemical characteristics and environmental conditions. Investigation on the effect of various PCMs on reducing SCA under different conditions favors the safe utilization of Cd-contaminated soil. Herein, a meta-analysis of literature published before August 2021 was carried out. A total of 342 independent observations were obtained from 42 published papers which included 9 factors that may affect the passivation effect of fertilizer content: phosphorus type, phosphorus application rate, soil pH, soil CEC, soil organic matter, experiment type, and time. Results of boosted regression tree analysis showed that the application rate is the most important factor contributing to the SCA, followed by soil pH and duration. Results of this meta-analysis showed that medium P input shows potential for reactivating the SCA. Under alkaline soil conditions and high soil CEC values, PCM input can better deactivate SCA. In addition, the difference from the previous understanding is that under the medium input of phosphorus-containing fertilizer (90–500 mg P∙kg⁻¹), it will significantly increase the content of available cadmium in soil. In addition, future recommendation for exploring novel PCMs and suitable strategies for controlling the SCA though PCM application were also proposed. Our works may promote the interpretation of the interference factors on the SCA changes and fill the research gaps on utilization of PCM in Cd-polluted soil remediation.
显示更多 [+] 显示较少 [-]Extreme Level of CO2 Accumulation into the Atmosphere Due to the Unequal Global Carbon Emission and Sequestration 全文
2022
Hossain, Md Faruque
Global total CO₂ emission and sequestration are being analysed from 1960 to 2029 reports interpreted from DEP, DOE, IPCC, CFC, CDIAC, IEA, UNEP, NOAA, and NASA. Consequently, these reports have been transcribed into each 10-year-period data set by using MATLAB software to accurately calculate the decadal emission and sequestration rate of total CO₂ within the world. Then, these data were further analysed to determine the final annual increasing rate (yr ⁻¹) of CO₂ accumulation into the atmosphere. The study revealed that total CO₂ emissions throughout the world since the 1960s have been increasing rapidly and in the recent year the net CO₂ increasing rate is 2.11% annually. If the current annual CO₂ growth rate is not copped now, the atmospheric CO₂ accumulation shall indeed reach at a toxic level of 1200 ppm concentration of CO₂ into the atmosphere in 53 years. Consequently, the entire human race will face severe breathing problems due to the toxic level of CO₂ presence in the air which indeed will create a serious environmental vulnerability to live mankind on Earth comfortably.
显示更多 [+] 显示较少 [-]Association of urinary arsenic and sleep disorder in the US population: NHANES 2015–2016 全文
2022
Rahman, Humairat H | Niemann, Danielle | Yusuf, Korede K
Arsenic is a known carcinogen and neurotoxin and is found in the natural earth crust. Arsenic exposure can develop depression, memory dysfunction, and neurodegenerative disorder. The mechanism of arsenic toxicity on the nervous system is not known. There is a lack of research on the association between arsenic exposure and sleep disturbance in humans. This study aims to investigate the relationship between six types of urinary speciated arsenic exposure and sleep disturbance in adults from the general population using the National Health and Nutrition Examination Survey (NHANES) 2015–2016 dataset. Sleep disturbance was measured using self-reported questionnaires, asking participants if they had ever told a doctor they had trouble sleeping. We utilized multivariate logistic regression analysis using complex survey procedures to examine the association between six types of urinary arsenic concentration and trouble sleeping. The total sample included 1,611 adults who were 20 years and older. Of the study participants, 30.0% had trouble sleeping. Compared to individuals with urinary arsenous acid below the lower level of detection (LLOD), those with urinary arsenous acid at or above the detection limit had lower odds of trouble sleeping [odds ratio: 0.72 (95% confidence interval 0.51–1.00, p-value: 0.05)]. The other five types of urinary speciated arsenic studied (arsenic acid, arsenobetaine, arsenocholine, dimethylarsinic acid, monomethylarsonic acid) were not associated with a sleep disorder. More studies are required to confirm or refute these findings.
显示更多 [+] 显示较少 [-]Factors affecting managers’ intention to adopt green supply chain management practices: evidence from manufacturing firms in Jordan 全文
2022
Jum’a, Luay | Ikram, Muhammad | Alkalha, Ziad | Alaraj, Maher
Global sustainability movement encourages companies to adopt and implement green supply chain management (GSCM) practices across the organization. Moreover, the integration of green practices into traditional supply chain is still to be a difficult task in manufacturing sector. However, empirical studies regarding the identification of influential factors affecting GSCM adoption among supply chain managers in manufacturing sector are under researched. This study assesses the factors affecting GSCM adoption in Jordan manufacturing firms. A well-structured questionnaire was administered for data collection. A valid 376 responses were collected from different manufacturing firms in Jordan. The data were analyzed, and the proposed model was validated using the structural equation modeling (SEM) approach. Results reveal that four factors, namely, supplier, environmental, customer, and cost factors significantly influence the intention to adopt GSCM among managers. The firm size had significantly moderated the relationship between market/financial and GSCM adoption, internal factor and GSCM adoption. The study will help the policymakers to understand the drivers of GSCM adoption among managers and assist them in implementing GSCM practices according to the size of the firm. This study is first of its kind to analyze the role of firm size as a moderator on the relationship between market/financial, supplier, governmental, environmental, internal, customers, cost factors, and GSCM in the context of Jordon.
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