Refine search
Results 5491-5500 of 6,554
Decoupling of energy-related CO2 emissions from economic growth: a case study of Bangladesh Full text
2020
Hossain, Md Afzal | Chen, Songsheng
The objective of this paper is to appraise the decomposition along with decoupling elements that affected the nexus between energy-related CO₂ emissions and the economic development of Bangladesh by applying the logarithmic mean Divisia index and Tapio model. The paper provides an effective policy that will enable Bangladesh to improve its environmental aspect and stimulate sustainable economic development. The analysis comprehends three economic sectors, and the decoupling determinative is fragmented into five elements. The results revealed that Bangladesh achieved weak decoupling throughout the analysis cycles except between the cycles of 1990–1991, 1992–1993, 1995–1996, 1997–1999, 2003–2004, 2012–2013, and 2015–2017 in which a strong decoupling occurred. From the disintegration of various components’ frame of reference, it can be seen that change in scale effect causes a substantial increase in carbon emissions and economic structure together, whereas energy intensity plays an imperceptible role in the increase in carbon emissions. On the other hand, the emission is the only element that is responsible for a decrease in carbon emissions. From a comparative sectoral analysis point of view, scale effects are liable for increasing carbon emissions in all three sectors. Hence, precautionary information campaign should be taken to communicate a comprehensive countrywide moderation strategy and appropriate modification engagements for initiating a low-carbon community.
Show more [+] Less [-]Exploring the photo protective potential of solid lipid nanoparticle-based sunscreen cream containing Aloe vera Full text
2020
Rodrigues, Lavita Roshni | Jose, Jobin
Nowadays, the sunscreen creams are composed of mostly synthetic chemicals and other organic compounds which were found to enter into the blood stream on topical application raising concerns in the scientific community. The scientific community has now shifted their attention to herbal formulations due to toxicity of these synthetic molecules. Aloe vera is a xerophitic plant having excellent anti-oxidant properties. The permeation effect and drug stability of the drug candidate can be significantly enhanced by formulating it into solid lipid nanoparticles (SLN). The main objectives of the study were to formulate and evaluate Aloe vera-loaded SLN sunscreen cream and to determine its photoprotective potential. The Aloe vera-loaded SLNs were formulated by microemulsification technique. The developed SLNs were studied for its entrapment efficiency, poly dispersity index (PDI), zeta potential, particle size, and other characterization techniques. Finally, the optimized SLNs were incorporated into the sunscreen cream and evaluated for its spreadability, viscosity, extrudability, drug content, in vitro drug release, ex vivo permeation, determination of sun protection factor (SPF), skin irritation test, and accelerated stability studies. The in vitro SPF was found out to be 16.9 ± 2.44 and the in vivo SPF observed to be approximately 14.81 ± 3.81, respectively. Stability studies were performed under accelerated conditions and no appreciable changes in the parameters were noticed. The solid lipid nanoparticles of Aloe vera were incorporated into a cream and the SPF of the resultant sunscreen cream was found to be on par with the sunscreens that were currently available in the market.
Show more [+] Less [-]Does environment-biased technological progress reduce CO2 emissions in APEC economies? Evidence from fossil and clean energy consumption Full text
2020
Yang, Guanglei | Zha, Donglan | Zhang, Chaoqun | Chen, Qian
Environment-biased technological progress plays a critical role in carbon reduction, while the association among environment-biased technological progress, energy consumption, and carbon emissions has not been paid enough attention. Working with a unique spatial panel dataset of APEC economies spanning the 2000–2017 period, we employed the nonspatial panel model and the spatial panel model to investigate the role of fossil energy (FE) and clean energy (CE) consumption in carbon dioxide (CO₂) abatement through environment-biased technological progress (EBTP). We decomposed EBTP into both emission-reducing biased technological progress (ErBTP) and energy-saving biased technological progress (EsBTP). The results show that the direct effect of EBTP on CO₂ emissions was significantly negative and that the direct effect of ErBTP was significantly larger than that of EsBTP. EBTP reduced CO₂ emissions through CE consumption, whereas it increased CO₂ emissions through FE consumption, that is, EBTP had a “backfire effect” on FE consumption. More into detail, ErBTP had a larger effect on CO₂ emissions in developing economies, while EsBTP played a more important role in developed economies. Furthermore, the results of the robustness test were consistent with our findings. Finally, several policy options were suggested to reduce CO₂ emissions in APEC economies.
Show more [+] Less [-]Synthesis optimisation and characterisation of chitosan-calcite adsorbent from fishery-food waste for phosphorus removal Full text
2020
Pap, Sabolc | Kirk, Caroline | Bremner, Barbara | Turk Sekulic, Maja | Gibb, Stuart W. | Maletic, Snezana | Taggart, Mark A.
Here, Box-Behnken design (BBD) approaches were utilised to optimise synthesis methodology for the chitosan-calcite rich adsorbent (CCM) made from fishery-food waste material (crab carapace), using low-temperature activation and potassium hydroxide (KOH). The effect of activation temperature, activation time and impregnation ratio was studied. The final adsorbent material was evaluated for its phosphorus (P) removal efficiency from liquid phase. Results showed that impregnation ratio was the most significant individual factor as this acted to increase surface deacetylation of the chitin (to chitosan) and increased the number of amine groups (–NH₂) in the chitosan chain. P removal efficiency approached 75.89% (at initial P concentration of 20 mg/L) under optimised experimental conditions, i.e. where the impregnation ratio for KOH:carapace (g/g) was 1:1, the activation temperature was 105 °C and the activation time was 150 min. Predicted responses were in good agreement with the experimental data. Additionally, the pristine and CCM material were further analysed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Brunauer-Emmett-Teller technique (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Characterisation showed enhancements in surface chemistry (introducing positively charged amine groups), textural properties and thermal stability of the CCM.
Show more [+] Less [-]Effect of LCRS clogging on leachate recirculation and landfill slope stability Full text
2020
Feng, Shi-Jin | Chen, Zheng-Wei | Zheng, Qi-Teng
Vertical wells are commonly used for recirculating leachate into a landfill which can offer significant environmental and economic benefits. However, in some cases, the leachate collection and removal system (LCRS) at the bottom is overloaded and clogged due to biological and chemical processes. This results in a relatively high leachate level which could pose a threat to landfill slope stability. This study develops a three-dimensional landfill slope model with vertical recirculation wells and then investigates the effect of LCRS clogging on leachate recirculation and slope stability in terms of leachate saturation, pore water pressure, and factor of safety (FS) of a landfill slope. The results show that with an increase in clogging level that is characterized by an increased leachate level, the pore water pressure below the well injection screen is significantly increased by leachate recirculation, giving rise to a decreased slope FS value. In such conditions, the landfill slope formed by highly anisotropic waste is more likely to suffer instability. To prevent this kind of slope failure, a safe injection pressure of vertical recirculation wells is proposed for a wide range of parameter combinations involving waste anisotropy, clogging level, and the setback distance from the slope surface. This design guideline can be used to control the injection pressure in leachate recirculation applications and contributes to a better understanding of the slope stability of a bioreactor landfill.
Show more [+] Less [-]Effect of short-term intermittent exposure to waterborne estradiol on the reproductive physiology of the round goby (Neogobius melanostomus) Full text
2020
Guellard, Tatiana | Kalamarz-Kubiak, Hanna | Arciszewski, Bartłomiej
The objective of this study was to determine how the short-term exposure to a supraphysiological concentration of waterborne 17β-estradiol (E₂) influences on melatonin (Mel) and thyroxine (T₄) concentrations in plasma and E₂ and 11-ketotestosterone (11-KT) concentrations in plasma and gonads in both sexes of round goby (Neogobius melanostomus) during the pre-spawning, spawning, late spawning and non-spawning phases. The experimental protocol was based on short-term, repeated exposures of fish to a supraphysiological dose of waterborne E₂. Mel level was unchanged on exposure to E₂ during the investigated phases, and its role in determining a time frame for spawning in both sexes of round goby seems to be stable in those conditions. T₄ and sex steroids (E₂ and 11-KT) were sensitive to the exposure of E₂, and those changes influence gonads by accelerating oocyte development, ovulation and regression and inhibiting spermatogenesis in this species. The results demonstrate that the physiological responses of fish in all investigated phases were altered over a short window of exposure, indicating that short-term exposure to a supraphysiological dose of E₂ may impact fish in the wild. Furthermore, round goby can be recommended as a very suitable model for studying endocrine disruptors, which is sensitive to even short exposure to E₂.
Show more [+] Less [-]Decomplexation of Cu(II)/Ni(II)-EDTA by ozone-oxidation process Full text
2020
Xu, Suyun | Yan, Ning | Cui, Minghao | Liu, Hongbo
In this study, ozone-oxidation was used to treat synthetic chemical plating solution containing Cu(II)/Ni(II)-EDTA solution to realize the purpose of decomplexation. The effects of solution pH, initial concentration of Cu(II)/Ni(II)-EDTA, the molar ratio of EDTA to Cu(II)/Ni(II), and the coexistence of Cu(II)/Ni(II) on their removal efficiencies were investigated. The degradation of EDTA-Cu(II) and EDTA-Ni(II) were mainly attributed to OH oxidation, and the removal rates of Cu(II)/Ni(II) depend on the complete decomplexation. The removal rates of Cu(II) and Ni(II) was affected by the pH of solution, and the optimal pH was found to be 7–9; nevertheless, their removal rates can still be up to 90% even in acidic pHs of 3~5. When the molar ratio of EDTA to Cu(II)/Ni(II) increased from 1:1 to 3:1, the kinetics of metal ion removal rate declined from 0.0788 and 0.1139 min⁻¹ to 0.0250 and 0.0271 min⁻¹. The synergistic effect was found in the Cu(II)/Ni(II) blended system due to the higher catalytic capability and the lower complexation affinity toward EDTA for Ni(II). In summary, ozone oxidation can be considered as an effective technology to realize the complete decomplexation of Cu(II)/Ni(II)-EDTA that contained in chemical plating industry wastewater. Graphical Abstract
Show more [+] Less [-]Toxic element (As and Hg) content and health risk assessment of commercially available rice for residents in Beijing based on their dietary consumption Full text
2020
Li, Libing | Feng, Huashuai | Wei, Junxiao
Arsenic (As) and mercury (Hg) are toxic elements that are often classified as heavy metals, much like cadmium (Cd) and lead (Pb) and others. In this study, we determined the As and Hg contents in rice samples obtained from commercially available rice in Beijing and the health risks associated with daily dietary exposure to As and Hg by the consumption of this rice. Furthermore, the pollution levels of the rice were evaluated based on the Nemerow index. For this purpose, we collected 353 rice samples from 16 municipal districts in Beijing and determined the As and Hg contents in these samples by microwave digestion and inductively coupled plasma mass spectrometry (ICP-MS). The results were as follows: (i) the average content of As in the collected rice samples was 154.91 μg/kg (95% confidence interval (CI) of 139.90–169.92 μg/kg), and the average content of Hg was 2.02 μg/kg (95% CI of 1.25–2.79 μg/kg), which did not exceed the limits established by China’s National Standard; (ii) the Nemerow index indicated that the As and Hg contents in these rice samples were safe; (iii) the dietary exposure to As and Hg by rice consumption was, respectively, 15.35 μg/day and 0.20 μg/day, which accounted for 12.91% and 3.35% of the total dietary exposure, respectively; (iv) the hazard quotients (HQs) of As and Hg by the dietary consumption of rice were, respectively, 0.77 and 0.03, and both the HQ and hazard index (HI is 0.8) were less than one. These results indicate that dietary exposure to As and Hg would have no detrimental effect on the health of the residents in the study area; however, the possible carcinogenesis by As in these residents warrants serious attention.
Show more [+] Less [-]Effects of human-induced eutrophication on macroinvertebrate spatiotemporal dynamics in Lake Dianchi, a large shallow plateau lake in China Full text
2020
Zhang, Junqian | Wang, Chouming | Jiang, Xiaoming | Song, Zhuoyan | Xie, Zhicai
The Yungui Plateau lakes, which are characterized by a highly endemic biodiversity, have been suffering severely from anthropogenic intervention in the recent decades. Studies on the response of these biodiversity to human-mediated effects are still limited. Here, we selected the typical Lake Dianchi to investigate the correlation between macroinvertebrate spatiotemporal dynamics and human-induced eutrophication across a 2-year span (2009–2010). A total of 26 taxa were recorded, and the assemblage pattern of the macroinvertebrate community was mainly controlled by the spatiotemporal (region, season, and year) density fluctuations of some pollution-tolerant species (Limnodrilus hoffmeisteri, Tubifex tubifex, Branchiura sowerbyi, and Chironomus plumosus). Taxon richness, total density, biomass, and the abundance of Oligochaeta and Chironomidae decreased from the north to the south of the lake but were much higher in 2009 than in 2010. Moreover, the high densities of total assemblages and oligochaete occurred during spring and/or autumn, whereas that of chironomids was only high during summer. The contributions of important factors varied in different seasons, but the community variations were mainly shaped by eutrophication-related factors (e.g., Chla, N, and P). Variance partitioning analyses showed that aquatic factors were able to explain more community variations than sediment (6.9–36.6 vs. 5.3–14.7%) across seasons, but their interactive effects were negligible. The results of this study will be beneficial for restoring and managing hypereutrophic lakes in the Yungui Plateau and imply the necessity of long-term monitoring in bioassessment projects involving intensively disturbed lakes.
Show more [+] Less [-]Glutathione S-transferase activity and genetic polymorphisms associated with exposure to organochloride pesticides in Todos Santos, BCS, Mexico: a preliminary study Full text
2020
Santillán-Sidón, Patricia | Pérez-Morales, Rebeca | Anguiano, Gerardo | Ruiz-Baca, Estela | Osten, Jaime Rendón-Von | Olivas-Calderón, Edgar | Vazquez-Boucard, Celia
The objective of this study was to identify and evaluate the impact of exposure to mixtures of organochloride pesticides (OCPs) in agricultural workers by detecting their effects on the activity of the enzyme glutathione S-transferase (GST) and the presence of polymorphisms of the GSTT1 and GSTM1 genes. The presence of OCPs was identified and quantified by gas chromatography, while spectrophotometry was used to measure enzymatic GST activity. The frequencies of the GSTM1 genotypes were analyzed by multiplex PCR. A total of 18 metabolites of OCPs were identified in the workers’ blood, most of which are either prohibited (DDT and its metabolites p, p’DDD and p, p’DDE, dieldrin, endrin, aldrin) and/or restricted (δ hexachlorocyclohexane, cis chlordane, methoxychlor, and endosulfan). The results obtained indicate lower levels of GST activity at higher OCPs concentrations detected in blood from exposed workers, together with an increase in OCP levels in individuals who presented the GSTT1*0 and GSTM1*0 genotypes. These conditions place the detoxification process in agricultural workers with null polymorphisms in the GST genes and high concentrations of OCPs in the blood (especially DDT and its metabolites, DDD and DDE) at risk, and increase their susceptibility to develop serious diseases.
Show more [+] Less [-]