خيارات البحث
النتائج 4351 - 4360 من 8,010
Evaluating the effect of dermaseptin S4 and its derivatives on multidrug-resistant bacterial strains and on the colon cancer cell line SW620 النص الكامل
2021
Belaid, Afifa | Braiek, Afef | Alibi, Sana | Hassen, Wafa | Beltifa, Asma | Nefzi, Adel | Mansour, Hedi Ben
Dermaseptins are peptides found in the skin secretions of Phyllomedusinae frogs. These peptides exert a lytic action on various microorganisms and have no considerable hemolytic effect except dermaseptin S4 (DS4) which exhibits a powerful cytotoxic effect. Therefore, we synthesized several analogs of DS4 in an attempt to find molecules with a weak hemolytic effect and significant bioactivities. In this study, we performed the synthesis of truncated peptides by introducing C-terminal and N-terminal amino acid deletions of the native sequence. All peptide analogs, in comparison with parental peptide, were tested firstly on human red blood cells to work out their cytotoxicity, secondly on the multidrug-resistant bacteria by trying to find MICs, and finally on colon cancer tumor cell line SW620 using the MTT test so as to investigate the anti-proliferative effect. Our results showed that, on the one hand, the N terminus of the native peptide was necessary for the antibacterial activity and the anti-proliferative effect of the peptide. On the other hand, the hemolytic activity was more notable in the sequences broken down on the C-terminal side.
اظهر المزيد [+] اقل [-]A Bibliometric Study on the Application of Advanced Oxidation Processes for Produced Water Treatment النص الكامل
2021
Simões, Andressa Juliana Almeida | Macêdo-Júnior, Roberto Oliveira | Santos, Brenda Lohanny Passos | Silva, Daniel Pereira | Ruzene, Denise Santos
The growing global concern with water resources management has driven the search for more effective treatments for industrial effluents. The produced water is inserted in this scenario as one of the largest effluents generated by the oil industry. Besides, it cannot be discarded or reused without proper treatment due to its complex and toxic chemical composition. A bibliometric study was performed on the Scopus database from inception to 2020 in order to map the evolution of scientific publications related to the advanced oxidation processes based on reactions with ozone and Fenton’s reagent. The results reinforced the efficiency of such processes for treating the produced water and the increasing of publications in the last few years, although the first document appeared only in 1995. China was the leading country in this research area, followed by Brazil and the USA. The most relevant journals were the Environmental Science & Technology and the Journal of Hazardous Materials. The research trends pointed out that the use of Fenton, photo-Fenton, and ozonation processes has been associated with other treatment methods to enhance the removal of contaminants in the produced water samples. However, the documents selected revealed the limitation on these processes due to the high costs with energy consumption. The present study can help other researchers mainly due to the few studies in this area, which demonstrates the importance of this prospection to support the development and application of advanced oxidation processes on produced water treatments.
اظهر المزيد [+] اقل [-]Environmental impact of mining-associated carbon emissions and analysis of cleaner production strategies in China النص الكامل
2021
Yang, Boyu | Bai, Zhongke | Zhang, Junjie
In recent years, concern has been increasing regarding the carbon emissions generated by mining activities. China is an extremely large coal producer (3695 Mt/2015) and consumer (3698 Mt/2015), and Shanxi Province (i.e., a major coal-producing province in China) is a crucial element in China’s energy conservation and emission reduction goals. In this study, the Pingshuo mining area (PMA) in Shanxi Province was chosen as a case to analyze the dynamic changes in carbon emissions based on the Intergovernmental Panel on Climate Change (IPCC) method, and the factors influencing carbon emissions were analyzed via the IPAT equation. Carbon emission sources in opencast mines mainly included fuel and explosive use, coal mine methane escape, coal and gangue spontaneous combustion, and electricity consumption. The carbon emission of the PMA increased from 4 × 10⁴ Mg in 1986 to 1.05 × 10⁶ Mg in 2015, with an average annual increase of 11.64%. In the PMA, 4.71 × 10⁶ Mg of carbon emissions from fuel consumption accounted for 41.79% of carbon emissions, and 5.26 × 10⁶ Mg of carbon emissions from methane emissions accounted for 46.66%. Carbon emissions from explosives and electricity use were 4.1 × 10⁵ Mg and 8.8 × 10⁵ Mg, respectively. In this mining area, the factors influencing carbon emissions included population, GDP, and coal output. The results of this study not only provide a reference for cleaner production in mining areas but also lay a foundation for the study of global opencast coal mining carbon emissions.
اظهر المزيد [+] اقل [-]Exploring the therapeutic potential of marine-derived bioactive compounds against COVID-19 النص الكامل
2021
Singh, Rachana | Chauhan, Niketa | Kuddus, Mohammed
The ocean is the most biodiverse habitat of various organisms. The organisms surviving in the harsh conditions of the ocean consist of several spectacular properties and produce bioactive compounds of pharmacological importance. These compounds are effective even in small quantities with various immunomodulatory qualities such as antioxidant and anti-inflammatory properties. Though the vaccines for COVID-19 are developed, and drug development is also in progress, but till now no effective drug is available for this deadly virus. Researchers are mining the huge data of bioactive compounds to develop the specific drug for COVID-19. The use of the repurposed drugs is challenging against the rapidly mutating virus with variable symptoms and mode of transmission. This review is an attempt to compile all the spattered data of marine-derived bioactive compounds with antiviral properties and to explore their therapeutic potential against COVID-19.
اظهر المزيد [+] اقل [-]Potential of ornamental monocot plants for rhizofiltration of cadmium and zinc in hydroponic systems النص الكامل
2021
Woraharn, Sasimar | Meeinkuirt, Weeradej | Phusantisampan, Theerawut | Avakul, Piyathap
Cadmium (Cd) and zinc (Zn) accumulation and uptake ability have been investigated in three ornamental monocot plants (Heliconia psittacorum x H. spathocircinata, Echinodorus cordifolius, and Pontederia cordata) grown in hydroponic systems. All study plants in the highest heavy metal treatments were found to be excluders for Cd and Zn with translocation factor values < 1 and bioconcentration factor (BCF) values > 100. The highest Cd and Zn accumulations were found in roots of E. cordifolius (4766.6 mg Zn kg⁻¹ and 6141.6 mg Cd kg⁻¹), followed by H. psittacorum x H. spathocircinata (4313.5 mg Zn kg⁻¹) and P. cordata (3673.3 mg Cd kg⁻¹), respectively, whereas shoots had lower performances. However, P. cordata had the lowest dry biomass production compared to the other two plant species in this study. As a result of dilution effects, heavy metal accumulation for all study plants was lower in the combined heavy metal treatments than in solely Cd and Zn only treatments. At the end of experiments, the highest uptakes of Cd and Zn were found in H. psittacorum x H. spathocircinata (62.1% Zn²⁺ from 10 mg Zn L⁻¹ solution) and E. cordifolius (27.3% Cd²⁺ from 2 mg Cd L⁻¹ solution). Low percentage metal uptakes were found in P. cordata; therefore, E. cordifolius and H. psittacorum x H. spathocircinata are clearly better suited for removing Cd and/or Zn from contaminated waters and hydroponic systems.
اظهر المزيد [+] اقل [-]Photoactivation and photoregeneration of TiO2/PAC mixture applied in suspension in water treatments: approach to a real application النص الكامل
2021
Moles, Samuel | Berges, Javier | Ormad, María P. | Nieto-Monge, M Jesús | Gómez, Jairo | Mosteo, Rosa
The process TiO₂/PAC/UV-vis has been under study and compared with the isolated treatments of adsorption and photocatalysis determining possible synergies between adsorption and photocatalysis of target antibiotics: amoxicillin, enrofloxacin, sulfadiazine, and trimethoprim. The characterization of the TiO2/PAC mixture was carried out via FESEM and FTIR. Moreover, a kinetic study has been performed. The effect of UV-vis radiation and the type of matrix was analyzed in TiO₂/PAC/UV-vis process. The performance of this treatment has been monitored during three cycles, evaluating also the regeneration of TiO₂/PAC mixture by UV-vis light. TiO₂/PAC/UV-vis process allowed the removal of the antibiotics in the range 90–100% (an average removal of 93% of the initial concentration) after 60 min of treatment. However, only amoxicillin showed a significant synergy applying TiO₂/PAC/UV-vis process. Regarding matrix effect, no influence of the matrix type (ultrapure water or treated wastewater) was observed. Since PAC tends to be deactivated gradually, the TiO₂/PAC/UV-vis process performance decreases after each cycle in a 15% average. Finally, regeneration via UV-vis light started to be effective after a total of 4 h of regeneration.
اظهر المزيد [+] اقل [-]Synergistic effect of curcumin and chitosan nanoparticles on nano-hydroxyapatite-induced reproductive toxicity in rats النص الكامل
2021
Yousef, Mokhtar Ibrahim | Abd, Haitham Hassan | Helmy, Yasser Mohamed | Kamel, Maher Abdel-Nabi
Although the toxicity/biocompatibility of hydroxyapatite nanoparticles (HAPNPs), a prospective nano-biomaterial, is extensively studied, its interaction on the reproductive system following exposure is less exploited. In the present study, male rats were exposed to HAPNPs (300 mg/kg BW) to determine its possible reproductive toxicity. Also, the protective effects of chitosan (CSNPs, 280 mg/kg BW) and/or curcumin (CurNPs, 15 mg/kg BW) nanoparticles against HAPNPs-induced reproductive toxicity were studied. Animals were orally gavage daily with respective doses for 45 consecutive days. The obtained results indicated that HAPNPs caused a significant decrease in sperm count, sperm motility, testosterone hormone, steroidogenic enzymes (17-ketosteroid reductase and 17β-hydroxysteroid dehydrogenase), and antioxidant enzymes (glutathione peroxidase, glutathione S-transferase, catalase, and superoxide dismutase) in addition to total antioxidant capacity and reduced glutathione. LH and FSH, abnormal sperm, oxidative stress parameters (thiobarbituric acid-reactive substances (TBARS), nitric oxide (NO), and 8-hydroxy-deoxyguanosine (8-OHdG)), p53, TNFα, and interleukin-6 were significantly increased. The DNA damage was also analyzed by assaying 8-OHdG level which is considered as an indicator of genotoxicity and also suppression of the gene expression of mtTFA, induction of UCP2. Similarly, the histopathological evaluation was also changed following exposure to HAPNPs. The antioxidant activity of CSNPs and CurNPs showed mitigating effect against reproductive deterioration induced by HAPNPs throughout improvements in semen characteristics, sex hormones, inflammatory factors, and antioxidant status. The present study concluded that HAPNPs induced reproductive toxicity and it is important to use nano-antioxidants CSNPs and CurNPs as protective agents.
اظهر المزيد [+] اقل [-]The convergence of species composition along the drawdown zone of the Three Gorges Dam Reservoir, China: implications for restoration النص الكامل
2021
Zheng, Jie | Arif, Muhammad | Zhang, Songlin | Yuan, Zhongxun | Zhang, Limiao | Dong, Zhi | Tan, Xue | Charles, Wokadala | Li, Changxiao
Many rivers across the globe are regulated by dams, resulting in a strong alteration of the plant community composition of the drawdown zone. But, how these changes happen along the drawdown zone is less understood. In this study, a multivariate analysis was used to explore plant composition and similarity along the drawdown zone of the Three Gorges Dam Reservoir (TGDR), China. The dominant plant species, species richness, indicator species, and growth form were compared among the upstream, midstream, and downstream of the TGDR. Moreover, variation partitioning was used to determine the relative importance of environmental factors and spatial factors. Results showed that only a few species contributed the most to the community composition of the study area, and there was an extreme similarity in the plant community composition across the three different river segments. Furthermore, the results of the linear regression model demonstrated a steady declining trend in species richness along the drawdown zone, with the lowest species richness in the downstream segment. In addition, variation partitioning revealed 11% and 8% of the species composition change under environmental and spatial factors, respectively. Our results suggested that the dam impoundment led to the convergence of species composition along the drawdown zone of the TGDR, and environmental filtering and dispersal limitation played an imperative role in shaping species composition. The study highlighted the importance of restoration activities in overcoming the barriers of seed dispersal and seedling establishment in the degraded drawdown zone ecosystem of the TGDR.
اظهر المزيد [+] اقل [-]Risk analysis of inhaled hexavalent chromium (Cr6+) exposure on blacksmiths from industrial area النص الكامل
2021
Oginawati, Katharina | Susetyo, Septian Hadi | Rosalyn, Fiona Aulia | Kurniawan, Setyo Budi | Abdullah, Siti Rozaimah Sheikh
Chromium (Cr) is used as a mixture to improve strength and corrosion resistance. Milling and welding processes can expose workers to Cr through dermal exposure and inhalation. Cr exposure can be determined by urine testing. The purpose of this study was to analyze the concentration of Cr in urine (UCr) of workers. This study was carried out using a cross-sectional method. Sampling was conducted in the village of Mekarmaju, Bandung, Indonesia. The number of respondents included 30 blacksmiths, and the control group comprised 10 people who were not blacksmiths. Cr⁶⁺ exposure was measured using a personal sampling pump placed on the collar of the worker’s shirt as a breathing zone and then analyzed using a UV–visible spectrophotometer. UCr was measured with a graphite furnace atomic absorption spectrophotometer. The measured Cr⁶⁺ concentration in the exposed working area ranged from 0.03 to 0.63 mg/m³, whereas that in non-exposed area ranged from 0.02 to 0.04 mg/m³. Results showed that 16 out of 30 blacksmiths had a UCr concentration above the biological exposure index (BEI) value, 21 had a higher value than the threshold limit value (TLV), and 22 had hazard index (HI) values > 1, which indicated that Cr has a hazardous potential in the body. The analysis of the exposed and control groups showed a significant difference with a p value of 0.000 for TLV, chronic daily intake, and UCr. These results clearly showed that Cr⁶⁺ exposure may harm the health of these workers in the future. The results obtained in this study can be used to promote workers’ awareness on the potential health risk caused by Cr⁶⁺ exposure in the working environment.
اظهر المزيد [+] اقل [-]PCDD/Fs characteristics in flue gas and surrounding environment of iron and steel smelting industry النص الكامل
2021
Zhan, Mingxiu | Ma, Yufeng | Chen, Tong | Lin, Xiaoqing | Zhang, Shiying | Xu, Shuaixi | Li, Xiaodong | Yan, Jianhua
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) concentrations and distributions, emission factors and amounts, and ambient air and soil potential sources were investigated by collecting flue gas, ambient air, and soil samples from ten sintering furnaces and two electric arc furnaces of eight iron and steel smelting industries (ISSI) in China. In flue gas, the concentrations of PCDD/Fs ranged from 0.05 to 2.93 ng I-TEQ Nm⁻³ (mass, from 0.38 to 30.67 ng Nm⁻³), with an average of 0.42 ng I-TEQ Nm⁻³ (mass, 4.99 ng Nm⁻³), respectively. In ambient air, the concentrations ranged from 0.05 to 0.35 pg I-TEQ m⁻³ (mass, from 0.66 to 5.66 pg m⁻³), with an average of 0.20 pg I-TEQ m⁻³ (mass, 2.96 pg m⁻³), respectively. In surface soil, the concentrations ranged from 1.80 to 21.02 ng I-TEQ kg⁻¹ (mass, from 34.29 to 836.00 ng kg⁻¹), with an average of 5.82 ng I-TEQ kg⁻¹ (mass, 252.10 ng kg⁻¹), respectively. In deep soil, the concentrations ranged from 1.17 to 12.00 ng I-TEQ kg⁻¹ (mass, from 56.83 to 1488.00 ng kg⁻¹), with an average of 7.76 ng I-TEQ kg⁻¹ (mass, 433.20 ng kg⁻¹), respectively. Compared with emission limits for PCDD/Fs, the compliance was 78.9% in flue gas, 100% in ambient air, and 77.3% in soil. In congener profiles, the contributions of PCDFs were much higher than those of PCDDs in flue gas and ambient air, but the opposite was observed in soil. In ten sintering furnaces, the emission factors ranged from 22.11 to 901.22 ng I-TEQ t⁻¹, with an average of 373.80 ng I-TEQ t⁻¹, respectively. In two electric arc furnaces, the emission factors were 1667.52 and 894.96 ng I-TEQ t⁻¹, with an average of 1281.24 ng I-TEQ t⁻¹. According to both principal component analysis and hierarchical cluster analysis, all ambient air samples were affected by the emissions of PCDD/Fs from ISSIs, but to different degrees. However, the concentrations of PCDD/Fs in most soil samples were not influenced by the ISSI emissions.
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