Refine search
Results 2781-2790 of 7,290
Application of alginate-immobilized microalgae beads as biosorbent for removal of total ammonia and phosphorus from water of African cichlid (Labidochromis lividus) recirculating aquaculture system Full text
2022
Sarkheil, Mehrdad | Ameri, Maryam | Safari, Omid
Immobilized microalgae are a promising approach to incorporate microalgae in recirculating aquaculture system (RAS) for water purification. In the present study, two types of biosorbents including sodium alginate–immobilized Scenedesmus spp. and Chlorella spp. beads (algal beads) and sodium alginate beads without microalgae (alginate beads) were prepared. In the first experiment (static test), the potential of two biosorbents to remove different concentrations of total ammonia nitrogen (TAN) and total phosphorus (TP) from water was investigated. In the second experiment, two prepared biosorbents were used as biofilter in a RAS for rearing African cichlid (Labidochromis lividus) for 30 days. The survival rate and growth indices of fingerling fish and removal efficiency of two biosorbents for TAN, NO₃—N, and TP were determined. The results of static test showed that the removal efficiency and uptake capacity of the two biosorbents for TAN and TP increased during 30 days of the experiment, and these values for the algal beads were higher than the alginate beads. The TAN removal efficiency of the two biosorbents increased with increasing TAN concentration from 0.5 to 5 mg L⁻¹. The application of algal beads in the RAS improved the survival rate, final weight, final length, weight gain, and daily growth index (DGI%) indices of fish compared to those cultured in the RAS containing the alginate beads and the control (P<0.05). The algal and alginate beads decreased the TAN concentration by 42.85% and 28.57% compared to the control after 30 days of cultivation period, respectively. The uptake of nitrate was not observed by the two biosorbents during cultivation period. The TP removal efficiency of algal beads reached 44.90% after 30 days. The findings of this study indicated that the sodium alginate–immobilized microalgae could be considered as a suitable biofilter to be incorporated into a RAS to improve water quality and consequently enhance the growth and health of fish.
Show more [+] Less [-]Groundwater contamination source identification using improved differential evolution Markov chain algorithm Full text
2022
Bai, Yukun | Lu, Wenxi | Li, Jiuhui | Chang, Zhengbo | Wang, Han
The groundwater contamination source identification (GCSI) can provide important bases for the design of pollution remediation plans. The Bayesian theory is commonly used in the GCSI problem. Usually, we use the Markov chain Monte Carlo (MCMC) method to realize the Bayesian framework. However, due to the ill-posed nature of the GCSI and the system model’s complexity, the conventional MCMC algorithm is time-consuming and has low accuracy. In this study, we proposed an adaptive mutation differential evolution Markov chain (AM-DEMC) algorithm. In this algorithm, the Kent mapping chaotic sequence method, combined with differential evolution (DE) algorithm, was used to generate the initial population. In the iteration process, we introduced a hybrid mutation strategy to generate the candidate vectors. Moreover, we adaptively adjust the essential parameter F of the AM-DEMC algorithm according to the individual fitness value. For further improving the efficiency of solving the GCSI problem, the Kriging method was used to establish a surrogate model to avoid the enormous computational load associated with the numerical simulation model. Finally, a hypothetical groundwater contamination case was given to verify the effectiveness of the AM-DEMC algorithm. The results indicated that the proposed AM-DEMC algorithm successfully identified the contamination sources’ characteristics and simulation model’s parameters. It also exhibited stronger search-ability and higher accuracy than the MCMC and DE-MC algorithms.
Show more [+] Less [-]CircRNA circ_0000554 promotes ovarian cancer invasion and proliferation by regulating miR-567 Full text
2022
Wang, Hui | Zhang, Xuezhong | Qiao, Lujun | Wang, Heng
Circular RNAs (circRNAs) indicated potential modulating effects in tumor development. However, the specific role of circ_0000554 in ovarian tumor remains unknown. We found that circ_0000554 was overexpressed in ovarian tumor specimens and cells. Forced expression of circ_0000554 promoted cell growth, invasion, and epithelial to mesenchymal transition (EMT). We illustrated that miR-567 was downregulated in ovarian tumor specimens and cells. circ_0000554 was negatively correlated with miR-567 in ovarian tumor specimens. circ_0000554 sponged miR-567 expression in ovarian tumor. RIP assay showed that elevated expression of miR-567 could be enriched with circ_0000554. Luciferase reporter assay indicated that luciferase intensity was inhibited after treated with miR-567 mimic; however, the luciferase value of mut type was not decreased. Elevated expression of circ_0000554 suppressed miR-567 expression in HO8910 cell. circ_0000554 promoted ovarian tumor cell growth, invasion, and EMT via sponging miR-567. It suggested that circ_0000554 represent a potential therapy target for ovarian tumor.
Show more [+] Less [-]Time series analysis on association between ambient air pollutants and orofacial clefts during pregnancy in Lanzhou, China Full text
2022
Liu, Yanyan | Zhou, Li | Zhang, Wenling | Yang, Yanjun | Yang, Yan | Pan, Li | Ba, Yupei | Wang, Ruijuan | Huo, Yanbei | Ren, Xiaoyu | Bai, Yana | Zheng, Ning
Current studies on air pollutant exposure during pregnancy and orofacial clefts (OFCs) have inconsistent results, and few studies have investigated refined susceptible windows for OFCs. We aim to estimate association between air pollution and OFCs during the first trimester of pregnancy and identify specific susceptible windows. Birth data was obtained from Birth Defects Surveillance Network in Lanzhou from 2014 to 2019. Air pollution data and temperature data were obtained from ambient air monitoring stations and China Meteorological Data Network, respectively. A distribution lag nonlinear model (DLNM) was applied to estimate weekly-exposure-lag-response association between air pollutant levels and OFCs. The study included 320,787 perinatal infants from 2014 to 2019, of which 685 (2.14‰) were OFCs. The results demonstrated that exposure of pregnant women to aerodynamic diameter ≤ 10 μm (PM₁₀) at lag 4–5 weeks was significantly associated with the risk of OFCs, with the greatest impact at the lag 4 week (RR = 1.029, 95% CI = 1.001–1.057). Exposure to sulfur dioxide (SO₂) at lag 2–4 weeks was significantly associated with the risk of OFCs, with the greatest impact at the lag 3 week (RR = 1.096, 95% CI = 1.041–1.177). This study provides further evidence that exposure to air pollution increases the risk of OFCs in the first trimester of pregnancy.
Show more [+] Less [-]Modification effects of ambient temperature on ozone-mortality relationships in Chengdu, China Full text
2022
Zhang, Ying | Tian, Qiqi | Feng, Xinyuan | Hu, Wendong | Ma, Pan | Xin, Jinyuan | Wang, Shigong | Zheng, Canjun
A multitude of epidemiological studies have demonstrated that both ambient temperatures and air pollution are closely related to health outcomes. However, whether temperature has modification effects on the association between ozone and health outcomes is still debated. In this study, three parallel time-series Poisson generalized additive models (GAMs) were used to examine the effects of modifying ambient temperatures on the association between ozone and mortality (including non-accidental, respiratory, and cardiovascular mortality) in Chengdu, China, from 2014 to 2016. The results confirmed that the ambient high temperatures strongly amplified the adverse effects of ozone on human mortality; specifically, the ozone effects were most pronounced at > 28 °C. Without temperature stratification conditions, a 10-μg/m³ increase in the maximum 8-h average ozone (O₃–₈ₕₘₐₓ) level at lag01 was associated with increases of 0.40% (95% confidence interval [CI] 0.15%, 0.65%), 0.61% (95% CI 0.27%, 0.95%), and 0.69% (95% CI 0.34%, 1.04%) in non-accidental, respiratory, and cardiovascular mortality, respectively. On days during which the temperature exceeded 28 °C, a 10-μg/m³ increase in O₃–₈ₕₘₐₓ led to increases of 2.22% (95% CI 1.21%, 3.23%), 2.67% (95% CI 0.57%, 4.76%), and 4.13% (95% CI 2.34%, 5.92%) in non-accidental, respiratory, and cardiovascular mortality, respectively. Our findings validated that high temperature could further aggravate the health risks of O₃–₈ₕₘₐₓ; thus, mitigating ozone exposure will be brought into the limelight especially under the context of changing climate.
Show more [+] Less [-]Boosting photocatalytic efficiency of MoS2/CdS by modulating morphology Full text
2022
Sun, Yubing | Xiao, Jingting | Huang, Xinshui | Mei, Peng | Wang, Huihui
CdS-based composites as the highly efficient photocatalyst have been extensively investigated in recent years due to the suitable band gap and high photocatalytic efficiency. In this study, the effect of various factors (pH, U(VI) concentration, contents, and types of photocatalyst) on photocatalytic reduction of U(VI) by MoS₂/CdS composite was investigated. The optimized experimental conditions (e.g., pH 7.0, 20 mg/g U(VI), and 1.0 g/L photocatalyst) was obtained by batch techniques. Approximately 97.5% of U(VI) was photo-catalytically reduced into U(IV) by 2.5 wt% MoS₂/CdS composite within 15 min. After 5 cycles, 2.5 wt% MoS₂/CdS composite still exhibited the high removal efficiency of U(VI) under 50-min irradiation, indicating the good stability. The photo-reduction mechanism of U(VI) on MoS₂/CdS composite was attributed to the O⁻₂ radicals by quenching experiments, ESR, and XPS analysis. The findings indicate that CdS-based catalyst has a great potential for the photocatalytic reduction of uranyl in actual environmental remediation.
Show more [+] Less [-]Assessment of the temporal variability and health risk of atmospheric particle-phase polycyclic aromatic hydrocarbons in a northeastern city in China Full text
2022
Jiang, Qizheng | Zhang, Xianhui | Liu, Tong | Shi, Jie | Gu, Xiaolin | Xiao, Jieying | Fang, Jianlong
In this study, we examined the sources and temporal variability of 16 polycyclic aromatic hydrocarbons (PAHs) found in fine particulate matter (PM₂.₅) in a typical industrial city in northern China. We also evaluated the incremental lifetime cancer risk (ILCR) from the inhalation of these PAHs. Atmospheric PM₂.₅ samples were collected for 7 consecutive days each month from 2014 to 2019, and the 16 PAHs were measured using multiplex gas chromatography–tandem mass spectrometry. The carcinogenic risk of PAH exposure was assessed using the inhalation unit risk (IUR) and cancer slope factor (CSF) methods. The annual average concentrations of PM₂.₅ for each year from 2014 to 2019 were 102.87±55.25, 86.92±60.43, 69.17±37.74, 58.20±59.15, 56.01±34.52, and 52.54±58.15 µg m⁻³, and the annual average ΣPAH concentrations were 56.03±81.09, 47.99±79.30, 40.41±57.31, 33.57±51.79, 43.23±74.80, and 25.20±50.91 ng m⁻³, respectively. Source identification, using diagnostic ratio analysis, indicated that the major PAH sources were coal/biomass combustion, fuel combustion, and traffic emissions. A health risk assessment showed that the ILCR from PAH inhalation decreased throughout the study period and varied with age. The IUR and CSF methods both showed that the adult ILCR exceeded 1.0×10⁻⁶. These findings demonstrate the importance of addressing the carcinogenic risk of PM₂.₅-bound PAHs, particularly in adults.
Show more [+] Less [-]Antimicrobial resistance genes in microbiota associated with sediments and water from the Akaki river in Ethiopia Full text
2022
Yitayew, Berhanu | Woldeamanuel, Yimtubezinash | Asrat, Daniel | Rahman, Aminur | Mihret, Adane | Aseffa, Abraham | Olsson, Per-Erik | Jass, Jana
The spread of antimicrobial-resistant pathogens is a global health concern. Most studies report high levels of antimicrobial resistance genes (ARGs) in the aquatic environment; however, levels associated with sediments are limited. This study aimed to investigate the distribution of ARGs in the sediments and water of the Akaki river in Addis Ababa, Ethiopia. The diversity and abundance of 84 ARGs and 116 clinically important bacteria were evaluated from the sediments and water collected from five sites in the Akaki river. Most of the ARGs were found in the city close to anthropogenic activities. Water samples collected in the middle catchment of the river contained 71–75% of targeted ARGs, with genes encoding aminoglycoside acetyltransferase (aac(6)-Ib-cr), aminoglycoside adenylyl transferase (aadA1), β-lactamase (blaOXA₋₁₀), quinolone resistance S (qnrS), macrolide efflux protein A (mefA), and tetracycline resistance (tetA), were detected at all sampling sites. Much fewer ARGs were detected in all sediments, and those near the hospitals had the highest diversity and level. Despite the lower levels and diversity, there were no unique ARGs detected in the sediments that were also not detected in the waters. A wide range of clinically relevant pathogens were also detected in the Akaki river. The findings suggest that the water phase, rather than the sediments in the Akaki river, is a potential conduit for the spread of ARGs and antibiotic-resistant bacteria.
Show more [+] Less [-]Environmental technology spillovers and green start-up emergence: the moderating role of patent commercialization policy and patent enforcement Full text
2022
Dong, Shan | Gong, Hong | Liu, Ting
While research on the creation of green start-ups recognizes the influence of technology spillovers, less attention has been given to the relative importance of heterogeneous technology spillover sources and how they contribute to green start-up emergence. This study aims to fill this lacuna in the existing literature by investigating the relationship between green start-up entry and environmental technology in universities, research institutes, and firms. We primarily focus on the moderating effects of patent commercialization policy and patent enforcement in the relationship. The results show that environmental technology in universities, research institutes, and firms has a positive influence on both of green and non-green start-up emergences. Among them, firms play the most important role, followed by research institutes and universities. Besides, patent commercialization policy plays a negative role in shaping the relationship between green start-ups and environmental technology of universities and firms and the relationship between non-green start-ups and university environmental technology. However, the role of patent commercialization policy does not hold in other cases. Moreover, patent enforcement is negatively related to the relationship between both of green and non-green start-ups and environmental technology of universities and firms, except for research institutes. It indicates that regions should emphasize the dominant position of firms in environmental technology innovation and formulate specific innovation measures for different organizations to better foster local green entrepreneurship.
Show more [+] Less [-]Elevated ozone phytotoxicity ameliorations in mung bean {Vigna radiata (L.) Wilczek} by foliar nebulization of silicic acid and ascorbic acid Full text
2022
Shahzadi, Eram | Nawaz, Muhammad | Adrees, Muhammad | Asghar, Muhammad Jawad | Iqbal, Naeem
The present work provides an insight into the development of biochemical adaptations in mung beans against ozone (O₃) toxicity. The study aims to explore the O₃ stress tolerance potential of mung bean genotypes under exogenous application of growth regulators. The seeds of twelve mung bean genotypes were grown in plastic pots under controlled conditions in the glasshouse. Six treatments, control (ambient ozone level 40–45 ppb), ambient O₃ with ascorbic acid, ambient ozone with silicic acid, elevated ozone (120 ppb), elevated O₃ with ascorbic acid (10 mM), and elevated ozone with silicic acid (0.1 mM) were applied. The O₃ fumigation was carried out using an O₃ generator. The results revealed that ascorbic acid and silicic acid application decreased the number of plants with foliar O₃ injury symptoms in different degrees, i.e., zero, first, second, third, and fourth degrees; whereas 0–4 degree symptoms represent, no symptoms, symptoms occupying < 1/4, 1/4–1/2, 1/2–3/4, and > 3/4 of the total foliage area, respectively. Application of ascorbic acid and silicic acid also prevented the plants from the negative effects of O₃ in terms of fresh as well as dry matter production, leaf chlorophyll, carotenoids, soluble proteins and ascorbic acid, proline, and malondialdehyde (MDA) contents. Overall, silicic acid application proved more effective in reducing the negative effects of O₃ on mung bean genotypes as compared to that of the ascorbic acid. Three mung bean genotypes (NM 20–21, NM-2006, and NM-2016) were identified to have a better adaptive mechanism for O₃ toxicity tolerance and may be good candidates for future variety development programs.
Show more [+] Less [-]