heavy

摘要： Adsorption of heavy metal ions on chitosan-based adsorbents has been extensively investigated.However,few studies explored the feasibility of desorbing and regenerating chitosan.Adsorbents used after adsorption of heavy metals are discarded,and this practice exacerbates the solid treatment problem.Regeneration and reuse of exhausted adsorbents should be considered to operate environment-friendly and cost-effective adsorption.This review was performed to summarize the desorption of heavy metal ions and possible regeneration of chitosan-based adsorbents using various desorption agents such as acids,alkalis,salts,and chelating agents.It was found that the highest desorption efficiencies were obtained by acidic eluents.The percentage use of desorption agents for desorbing followed the order of acids(49.3%)>chelators(26.9%)>alkalis(14.9%)>salts(8.9%).Moreover,the proper desorption time was estimated to be 0.84 by 1.37 h.The beneficial information is provided for the regeneration and recovery of chitosan adsorbents.

摘要： 随着社会的发展,语言日益丰富,人类认知程度也在不断地提高。一词多义是语言发展的必然结果,在英语词汇中尤为普遍。多义词汇各个语义项之间存在着某种必然的联系。多义词汇在中英两种语言之间的差异,容易导致翻译的错误。本文从一词多义现象出发,以“heavy”为例,分析了海事英语文本中多义词“heavy”的翻译教学策略,以期对其它多义词的翻译教学有所借鉴。

摘要： The mushrooms are highly regarded as one of the most nutritious foods across the globe but also recognized bio-accumulators of heavy metals. The nature and level of industrial activities are continually changing and affecting the environment adversely. The mushrooms are not an exception and may inevitably have heavy metal contaminations. In this vein, this study aimed to determine heavy metal (Cu, Ni, Co, Zn, Pb, and Cd) uptake levels in wild edible mushrooms from the sites with different economic activities. The wild mushrooms considered for this study included Tente (Amanita Zambiana), Ichikolowa (Termitomyces Titaniscus), and Kabansa (Lactarius Tataniscus). The analysis of heavy metal concentration was carried out using atomic absorption spectrometry (AAS). For the selected mushrooms, concentration ranges (mg·kg-1 total dry weight (dw)) of 46.90 - 141.80 for Cu, 0.10 - 6.60 for Cd, 1.10 - 2.00 for Pb, 19.00 - 38.90 for Zn, 1.00 - 3.40 for Ni, and 44.80 - 79.70 for Co were obtained. However, for the respective soil samples, concentration ranges (mg·kg-1·dw) of 51.00 - 279.40 for Cu, 1.00 - 99.50 for Cd, 8.00 - 10.00 for Pb, 22.80 - 209.10 for Zn, 9.00 - 33.70 for Ni, and 60.00 - 111.90 for Co were obtained. To a certain degree, the concentrations reflected the impact of diversity in the surrounding activities. This study discovered that for the selected mushrooms, the contamination level of cadmium, cobalt, nickel, and copper exceeded the World Health Organization (WHO)/FAO (Food and Agriculture Organization) recommended limits. Although some minor aberrations from the prescribed limits were also observed in the case of copper and nickel. Further, the data established that the heavy metal concentrations in respective soils are not the sole determinant of concentrations in mushrooms. Thus, these findings merit attention as, in some cases, the extent of contamination has exceeded the WHO permissible limit, and it may pose a health risk to consumers.

摘要： Melatonin,as a ubiquitous indoleamine hormone,is synthesized primarily by the pineal gland.It has diverse biological effects through quite complex mechanisms.More recently,studies have focused on the mechanism of melatonin in anti-reproductive toxicity/damage.Since melatonin possesses strong antioxidant and anti-apoptotic properties,researchers have examined its potential role in protecting against male reproductive toxicity/damage,which may be induced by chemotherapy or environmental toxicants and can lead to male infertility.In this article,recent progress regarding the protective effects of melatonin on male reproductive toxicity/damage is reviewed.

摘要： Heavy metal contamination of sediments is a major risk to ecological systems and human health. Not only do sediments influence the quality of the water column, but can be transferred to micro biota and fishes, ultimately ending up at higher trophic levels in the food chain though biomagnification. This study was carried out to assess the contamination levels of heavy metals in the sediments of river Bonsa. Ten sediment samples were taken along the river and analyzed for Copper (Cu), Lead (Pb), Manganese (Mn), Iron (Fe), Zinc (Zn), Cadmium (Cd), Chromium (Cr), Cobalt (Co), and Nickel (Ni) using Atomic Absorption Spectroscopy (AAS). Data analysis was accomplished by comparing the measured heavy metal concentrations to Australian and New Zealand Environment and Conservation Council (ANZECC) and National Oceanic and Atmospheric Administration (NOAA) fresh water sediment quality guidelines and by the computation of geo-accumulation indices and enrichment factors. The results show that apart from Ni which had two of its sample concentrations (at BS1 21.167 mg/kg and at BS2 29.374 mg/kg) exceeding the ANZECC lower limit (21 mg/kg) guideline for fresh water sediment, all other heavy metals recorded concentrations below the lower limits of their respective ANZECC standards. Out of the 10 samples analyzed, 7 recorded Mn concentrations above the NOAA ARC TEL. A one-sample t-test also showed that the mean concentrations of Cu, Pb, Cd, Zn, Ni, and Cr were significantly lower than their respective ANZECC threshold values and Fe concentration was also significantly lower than the NOAA threshold;however, there was no significant difference between Mn mean value and the corresponding NOAA guideline value. The assessment of heavy metal pollution was derived using the Enrichment Factor (EF) and geo-accumulation indices (I-geo). The computed enrichment factors indicated that all the heavy metals except Ni are from natural sources (i.e., EF < 1.5) signifying a degree of heavy metal depletion rather than enrichment. The sources of Ni were attributed to domestic waste disposal into the river at sampling points BS1 and BS2 as well as run offs from a nearby auto mechanic workshop. All the metals had I-geo values between 0 and 1 (0 < I-geo < 1) denoting unpolluted to moderately polluted sediments. Thus, in terms of heavy metals, the river is unpolluted. These findings are very important as it shows that river Bonsa has not yet been impacted as far as heavy metals are concerned and the data gathered may serve as baseline for future studies.

摘要： The aim of this short review is to describe the role of myosin isoforms during the adaptation of skeletal muscle to prolonged physical activity (for example endurance exercise) and to show the coordination between changes in muscle oxidative capacity and myofibrillar apparatus in slow-twitch and fast-twitch muscles. Adaptational changes in myosin isoforms during long lasting muscle activity (decrease of MyHC IIb isoforms relative content and increase of that MyHC IIa and decrease of MyLC 1 fast isoforms in fast-twitch muscles) are in good coordination with changes of muscle oxidative capacity. These changes show that during regular endurance exercise fast-twitch muscle fibers (type IIA) are also recruited and create the potential source of increase in endurance capacity during the process of adaptation to the prolonged physical activity.

摘要： The study aims to investigate the current extent of physicochemical parameters and heavy metal contamination in the effluent of the Jaganpur sewage treatment plant (STP), Dayalbagh, Agra India. Majority of the nearby farmers have access to use of STP effluent in irrigation purposes for growing major edible crops. The problems of using STP effluent for irrigation purpose, continuous water quality analysis required. To check the quality of irrigation water, substantial physicochemical parameters accordance to Indian Standards (IS-Reaffirmed 2002/2003) analysed to calculate Sodium absorption ratio (SAR) and Residual sodium carbonate (RSC). To estimate the heavy metal pollution index (HPI) and metal quality index (MQI), toxic Heavy metals such as As, Cr, Mn, Fe, Ni, Cu, Zn, Pd, Cd, Co, and B also determined in the STP effluent with an AAS and results verified with ICP-OES against certified standards. The high value of SAR (range 13 to 20) and RSC (range -10 to 11) in STP effluent exceeded the permissible limit for irrigation purpose. On the other hand, HPI and MQI values (1692.4 and 58.1, respectively) show that high metal contamination mainly due to industrial and domestic wastewater does not treat appropriately in the sewage treatment plant. Thus it is suggested that further studies are carried out on the STP effluents to improve the water quality through proper treatment. Treated wastewater used for irrigation purposes needs to analyse the contamination like heavy metals and pinpoint the pollution sources.

摘要： The present work aims to evaluate and document the heavy metal distribution along Jazan coastline, southwest Saudi Arabia. Moreover, a trial for mining minerals from seawater has been performed where solvent extraction of a spike solution containing copper, cobalt and nickel has been investigated to attain the optimal extraction conditions. The optimum conditions are found to be 7 M hydrochloric acid concentration, 5 M [H+] for 3 min shaking time with Cyanex 923 solvent conc. of 0.1 M (1:1 aqueous/organic phase ratio) at temp. 25°C. These conditions realized 92.5% copper extraction as well as 95.6% and 96.2% for cobalt and nickel extraction respectively.

摘要： This study reports on the adsorption efficiency of a natural iron oxide from Mballam-Cameroon in comparison with synthesized goethite to simulta-neously remove cobalt and nickel ions from aqueous solutions. Chemical analysis on the natural iron oxide sample revealed iron as the main element and hematite (58.52%) goethite (19.42%), kaolinite (12.69%) and quartz (7.79%) as the component phases in the iron oxide sample. The iron oxide was found to be microporous (BET surface area 43.27 m2/g) with fairly spherical polydisperse particles. Results show maximum absorption for Co(II) and Ni(II) ions for both adsorbents occurred at an equilibrium contact time of 80 mins, dose rate of 0.1 g/L, and pH = 7. Goethite was slightly more efficient at removing target metal ions with maximal adsorbed quantities at 117.8 mg/g of Co(II) and 100.6 mg/g of Ni(II), and 103.9 mg/g of Co(II) and 85.2 mg/g of Ni(II) ions for natural iron oxide. Equilibrium modelling presented the Freundlich isotherm as the best fit model for both adsorbents and metal ions, indicating heterogeneity of the surface binding sites during adsorption. The pseudo-second order kinetic model was the best-fit model, indicating chemical adsorption between the adsorbent surface and metal ions, hence a good correlation between equilibrium and kinetics. The findings indicate that the efficacy of the natural iron oxide from Mballam is almost equivalent to that of synthetic goethite, validating its applicability for the simultaneous removal of cobalt and nickel ions from aqueous solution.

摘要： Tomato fruit enormously consumed in Burkina Faso is a source of health risk due to its quality. The plant of tomato cultivated in most the industrially polluted area as Ouagadougou, accumulates significant quantities of heavy metals and microorganisms and could be dangerous for consumption. The present study was conducted to investigate heavy metal and microbial contamination in soils wastewater and vegetables (tomato fruit) and to evaluate the possible health risks associated with the consumption of vegetables. Total concentrations of As, Cd, Cr, Cu, Hg, Ni, Se and Zn were determined using atomic absorption spectrophotometry. Transfer factor (TF), daily intake of metals (DIM) and health risk index (HRI) were also calculated. Microbial quality was analyzed for the presence of foodborne pathogens. The pH involved from 6.50 ± 0.1 to 9.40 ± 0.12 respectively for Boulmiougou and Kossodo. The mean metal concentrations indicated that soils were strongly polluted followed by wastewater and vegetable. The range of the mean values (in mg · kg-1) exhibited by As, Cd, Cr, Cu, Hg, Ni, Se and Zn in tomato fruit was 17.80 ± 0.32, 2.71 ± 0.02, 11.57 ± 0.2, 203.41 ± 1.20, 15.13 ± 0.30, 53.18 ± 0.20, 38.56 ± 0.10, 109.13 ± 0.25 concerning samples of Boulmiougou and 3.47 ± 0.15, 2.78 ± 0.01, 22.11 ± 0.1, 242.85 ± 2.10, 14.86 ± 0.10, 132.19 ± 1.50, 33.23 ± 0.15, 146.43 ± 1.12 for Kossodo. Microbial count was below to acceptable limits for vegetable, but underlined the presence of spoiler and foodborne pathogens. However, the daily intake of metals (DIM) and the health risk index (HRI) values were found to be under to the prescribed maximum tolerable.