This study aimed to perform a comparative analysis of the performance of five models (Gompertz, logistic, Richards, the first-order, artificial neural networks) in predicting methane production rate from anaerobic digestion of livestock manures. The input variables were fermentation time, digestion temperature, biogas temperature, ambient temperature, pH, and specific biogas production rate. The physicochemical compositions of cow manure and sheep manure showed that volatile solid (VS) contents were close to each other in manure compositions (77.6% and 64.7%, respectively), while the potential of methane production from cow manure (673.44 mL CH4/g VS) was greater than that from sheep manure (320.32 mL CH4/g VS). The determination coefficients (R2) for logistic function, Gompertz, Richards, the first-order, and ANN models were obtained as 0.968, 0.967, 0.975, 0.825, and 0.995 for the cow manure, respectively. In case of the sheep manure, the R2 values obtained from these models were 0.976, 0.979, 0.981, 0.968 and 0.991, respectively. Although the determination coefficients of all models were in satisfactory agreement with the experimental data, the ANN model showed competitive lower RMSE values of 0.111 and 0.164 for cow and sheep manure data sets, respectively, indicating its superior performance than other models.
Graft copolymerization is a distinctive approach to modify the inherently cheap natural fibers (NFs) using different initiators to incorporate synthetic polymer side chains allowing development of novel types of hybrid materials. This method has been widely applied to develop a variety of NFs based adsorbents for decontamination of toxic pollutants from the aqueous environment. However, the development of high-performance adsorbents from NFs is steady challenged by the need to preserve the sustainability during graft modifications and applications. This article critically reviews the progress on modifications of NFs by graft copolymerization of polar monomers on NFs using various initiating methods and their applications in wastewater treatment. Particularly, the applications of the grafted NFs in removal of heavy metal ions, synthetic dyes, oil spills and extraction of precious metals from wastewater are elaborated. The critical challenges to the viability and sustainability of NFs-based adsorbents with respect to functionalization by graft copolymerization and environmental impacts are discussed and the future research directions are also outlined.
The level of natural radiation in some regions of Ramsar, a northern coastal city of Iran, is known to be among the highest levels of natural radiation in the world. 226Ra existing in high concentrations in the soil of this region is washed by underground water and transferred to the surface. In this way, 226Ra enters the food chain of residents and substitutes within the hard body tissues of humans. 226Ra is one of the so-called bone seekers as its metabolic processes in the human body are similar to calcium and remains in hard tissues of body because of its long half-life, and being an alpha emitter causes dangerous effects on human health. The purpose of this study is to determine the concentration of 226Ra in the teeth of residents of these high-level natural radiation areas, compared with a control group. Thirteen teeth in five groups were studied as the case group and thirteen teeth in five corresponding control groups were inspected. The mean values of the activity of 226Ra in the case group and in the control group were 0.32 and 0.18mBqg(-1), respectively. 相似文献
Variations in breeding success of the Whiskered Terns (Chlidonias hybrida) were studied in two wetlands; Anzali (2005 and 2008) and Zarivar (2007–2008) in north and west Iran. Nesting success was
modeled and compared using information-theoretic approach implemented in program Mark in order to assess effects of colony
locations, years and nest initiation dates on the probability of daily nest survival. Clutch size did not vary between colonies
and years. Breeding success varied between colonies (Zarivar > Anzali), and years only in Anzali (2005 > 2008). Overall daily
nest survival was 0.977. (95% LCI 0.973, UCI 0.981), equivalent to a Mayfield nest survival of 0.317. (95% LCI 0.255, UCI
0.387). Egg-laying periods and colony site were important covariates affecting the daily survival rates (Σωi = 0.86 and Σωi = 0.83, respectively), while, the support for the effect of year was less (Σωi = 0.41). We concluded that Lake Zarivar provides a more favorable nesting location for Whiskered Terns probably because of
little changes in rainfall and water depth during the breeding seasons which influence breeding performance. 相似文献
Environmental Modeling & Assessment - Calibration of the rating curve is a challenge due to uncertainty in the parameters. This problem increases in an area with considerable seasonal... 相似文献
Marine gastropods, exposed to anthropogenic pollution, accumulate high chemical concentrations in their tissues, especially in the digestive glands. An evaluation of the impacts of cadmium (Cd) and permethrin (Perm), coupled with reproductive events (pre-spawning and post-spawning phase) throughout the year, was attempted by measuring catalase (CAT), a biomarker of defence, on Hexaplex trunculus experimentally exposed for 48 or 96 h. Specimens of gastropods were sampled from Bizerta Lagoon (Tunisia). The results show that CAT activity increased in gastropods exposed to the three cadmium concentrations (C1 Cd, 100 μg L(-1); C2 Cd, 200 μg L(-1); and C3 Cd, 300 μg L(-1)) and to the three permethrin doses (C1 Perm, 100 μg L(-1); C2 Perm, 150 μg L(-1); and C3 Perm, 200 μg L(-1)) tested. A decrease in CAT was noted in the digestive gland of the H. trunculus exposed to permethrin at the concentration of 200 μg L(-1) during the pre-spawning and post-spawning phases. H. trunculus in post-spawning was more sensitive to cadmium and permethrin than in the pre-spawning phase. The biochemical responses to pollutants (cadmium and permethrin) represented by CAT may act as a biomarker of exposure in this species. 相似文献
The Western Harbor (WH) became under stress in the past decades, following successive increase in population. This study deals with local distribution of total lead and its species in the WH sediments. The lead content was high and there was a relationship between its enrichment and oil dispersed from ships. The lowest total lead value was found in the harbor middle far from direct effects of pollution. A five-step sequential extraction scheme was applied to illustrate the contribution shared by each individual fraction in the total lead concentration in the WH sediments. The exchangeable fraction (F1) was very low. The bound to carbonate fraction (F2), the bound to iron-manganese oxide fraction (F3) and the bound to organic matter—sulfide fraction (F4) ranked fourth, second and third in abundance. Oxygen was the main factor controlling the value of F2. F3 gave a direct relationship with total lead. The high levels of F4 occurred at locations of low salinity and enriched with organic matter. The residual fraction (F5) dominated other lead species, reflecting the sediment composition and the amounts of discharged pollutants. 相似文献
The objective of this research was to study and identify ergonomic deficiencies in computer workstation design in typical offices. Physical measurements and a questionnaire were used to study 40 workstations. Major ergonomic deficiencies were found in physical design and layout of the workstations, employee postures, work practices, and training. The consequences in terms of user health and other problems were significant. Forty-five percent of the employees used nonadjustable chairs, 48% of computers faced windows, 90% of the employees used computers more than 4 hrs/day, 45% of the employees adopted bent and unsupported back postures, and 20% used office tables for computers. Major problems reported were eyestrain (58%), shoulder pain (45%), back pain (43%), arm pain (35%), wrist pain (30%), and neck pain (30%). These results indicated serious ergonomic deficiencies in office computer workstation design, layout, and usage. Strategies to reduce or eliminate ergonomic deficiencies in computer workstation design were suggested. 相似文献
A number of newly synthesized phthalidylamines and o-benzoylbenzamide derivatives were evaluated for some biological activities. Synthesis was established by condensation of 3-acetoxyphthalide 1 with morpholine, piperidine, N,N-diisobutyl-N,N-dibenzylamines and piperazine, which afforded N-(3-phthalidyl)amines 3a–d, and 4 respectively, while with N,N-diisopropylamine, o-formyl-N,N-diisopropyl benzamide 5a is formed exclusively. On the other hand, the reaction of 3-acetoxy-3-phenylphthalide 2 with secondary amines afforded o-benzoylbenzamide derivatives 5b–c, 6 in a high yield. The structure of the reaction products was established from their spectral data. These products were screened for antifungal, antibacterial and genotoxic effect. It was found that all tested compounds have antifungal activity. Compounds 1, 2, 3d and 5b were found to be active against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Genotoxic effects using Ames test showed that Compounds 1 and 2 have a weak base-pair substitution mutagenicity while a clear base-pair substitution mutagenic activity was shown by 3a using TA100-strain of Salmonella typhimurium. Compound 4 showed a frameshift mutgenicity while a weak oxidative mutagenic action was revealed by 6. No change on the mutagenicity of the tested chemicals was observed after using the S9 metabolic activation system. 相似文献
The physiological role of aluminum (Al) is not yet known. Exposure to Al may cause many human disorders. The aim of this study was to explore how occupational human exposure to Al might affect the body oxidative stress. The relation between Al toxicity and oxidative stress was studied in blood samples obtained from 45 primary Al production workers, with a minimum work history of three years in the age range of 29–52 years. They were evaluated for oxidative stress biomarkers including thiobarbituric acid reactive substances (TBARS) indicator of lipid peroxidation, ferric reducing ability of plasma (FRAP) indicator of total antioxidant capacity, total thiol molecules and Al level in blood. The results showed that workers have significantly higher blood Al levels and concomitant lower blood FRAP and total thiol molecules in comparison to controls. Smokers had lower total thiol molecules than non-smokers. The subjects who had a previous history of disease had lower FRAP levels. It is concluded that Al induces oxidative stress in primary Al production workers. Supplementation of workers with antioxidants may have beneficial effects. 相似文献
