Comparison of cellular and molecular cytotoxic mechanisms of Cochlodinium polykrikoides in isolated trout and rat hepatocytes

Harmful algal blooms produced by the marine ichthyotoxic dinoflagellate Cochlodinium polykrikoides are responsible for mass mortalities of wild and farmed fish globally. This study compared the cytotoxic mechanisms of C. polykrikoides total extract on both trout and rat liver hepatocytes. Trout hepatocytes were more sensitive than rat hepatocytes against C. polykrikoides extract. The effective concentration 50 after 3 hour incubation (EC50_3hr) concentrations found for C. polykrikoides extract in trout and rat hepatocytes (i.e., 50% membrane lysis in 3 hr) were Eq. 1 cell/ml and Eq. 240 cell/ml, respectively. C. polykrikoides extract exposure in both isolated trout and rat hepatocytes resulted in membrane lysis, reactive oxygen species formation, glutathione depletion, collapse of mitochondrial membrane potential, ATP depletion, increase in adenosine diphosphate (ADP)/adenosine triphosphate (ATP) ratio, cytochrome c release into the hepatocyte cytosol, and activation of caspases cascade. Trout hepatocyte toxicity was also associated with lysosomal membrane injury. Mitochondrial permeability transition in both trout and rat hepatocytes produced cytochrome c release from the mitochondrial intramembrane space into the cytosol. Thus, the cytochrome c release triggered activation of caspase-3 and apoptosis. Finally, data demonstrated that C. polykrikoides extract may induce more apoptotic phenotype in rat than trout hepatocytes, which in the latter favored predominantly necrotic mode of cell death.     

Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater

In this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H₂O₂ residual in the effluent of the combined UV-C/H₂O₂-VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOC_o) and hydrogen peroxide (H₂O_2o) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum conditions to achieve the maximum percentage TOC removal of 46.19% and minimum H₂O₂ residual of 1.05% were TOC_o of 213 mg L^?1, H₂O_2o of 450 mg L^?1, and irradiation time of 9 min. The attained optimal operating conditions were validated with a complementary test. Consequently, the TOC removal of 45.68% and H₂O₂ residual of 1.03% were achieved experimentally, confirming the statistical model reliability. Three individual processes, VUV alone, VUV/H₂O₂, and UV-C/H₂O₂, were also evaluated to compare their performance for the treatment of the actual SWW using the optimum parameters obtained in combined UV-C/H₂O₂-VUV processes. Results confirmed that an adequate combination of the UV-C/H₂O₂-VUV processes is essential for an optimized TOC removal and H₂O₂ residual. Finally, respirometry analyses were also performed to evaluate the biodegradability of the SWW and the BOD removal efficiency of the combined UV-C/H₂O₂-VUV processes.     

Factors affecting incentive dependency of residents to participate in e-waste recycling: a case study on adoption of e-waste reverse supply chain in Iran

Modern societies face a dilemma called electronic waste (e-waste). This waste, which may contaminate the soil or cause unwanted impacts on human health when treated improperly, is one of the fastest growing waste streams in developed as well as developing countries and has brought great environmental impacts. Developing countries like Iran also face this modern waste management challenge. In order for more appropriate disposal or, if possible, recycling of this waste, more attention has been paid to reverse logistics as the most appropriate way to manage them. The first and most important action to address e-waste and implementation of reverse logistics is to persuade residents to bring back their obsolete electronic products. This paper attempts to understand significant factors affecting residents’ incentive dependency to participate in e-waste recycling program. Socioeconomic and demographic information of different residents is discussed by means of logistic regression for the first time in Iran. The results show that about 58.7 % of residents will participate even if no incentive is given. Household income, household size, education, e-waste concern level, and marital status are the significant factors affecting the incentive dependency of respondents.     

A new method for calculating saddle seat height with an emphasis on optimal posture based on trigonometric relations

Introduction. Based on the literature, the ergonomic saddle chair provides the most appropriate posture for users. Determination of the seat height is critical to establish the proper posture, carried out using various methods of anthropometry. This study aimed to develop a simple and applied method for determining the saddle seat height with an emphasis on appropriate posture. Methods. In this study, anthropometric dimensions including weight, body height, popliteal height and seat height at 135° knee angle in 150 male and female dentists were measured. In the laboratory, to determine the ‘acetabuloischial number’, 25 male and female natural hip bones were measured. The mean saddle-chair height with knee angle of 135° was then compared by two different methods, field measurement and the new calculation method. Results. The results showed a strong correlation between data gathered from the two different methods, the field measurement and the new calculation method (98%), and Cronbach’s α from the intraclass correlation was equal to 0.994 (p?<?0.05). This indicated that the two methods produced similar results. Conclusion. The new method can be applied to calculate the optimal height of the saddle seat based on body height and popliteal height.     

Effect of pH values on the solubility of some elements in different soil samples

The purpose of this study is to know the concentrations of some heavy-metal elements (Zn, Pb and Cd) in different types of soil and the effect of pH values on their solubility. Two types of soil were selected from area adjacent to the sewage treatment plant, as well as from an agricultural area in the city of Al-Rass, Qassim, KSA for this purpose. The results showed high concentrations of elements in the acidic medium at pH 2, while concentrations decreased as the pH increased to reach the neutral medium. The decrease in concentrations was very clear in the alkaline medium and reached the lowest values at pH10. On the other hand, the highest concentrations were detected in soil adjacent to the sewage treatment specially for Pb and Cd in comparison with agricultural soil. The previous results show the urgent need for wastewater treatment and checking for pH values at standard limits before use in irrigation or discharge it on soil surface, as well as soil analysis prior to the planting and selection of appropriate plants by specialists for the health of citizens, where each plant characterise by its absorption for specific elements.     

An Experimental Study on Productivity and Quality Improvement of Horizontal Continuous Casting Process

The aim of the current work is to provide information on how to improve the productivity and quality in the Horizontal Continuous Casting process (HCC). After a first numerical 2D/3D survey about the solidification in the HCC, an experimental investigation has been carried out to validate numerical results. Some casting parameters have been measured and collected: inlet and outlet temperatures, flow rate, heat flux and casting temperature. The study results lead to a correlation between these casting parameters and the casting quality. To obtain the best quality for each alloy, a set of operating parameters has been proposed. There is a very good agreement between the current results and earlier numerical results. Also based on the results, one can gain an insight on the productions of each casting machine and the grades of its quality.     

Evaluation of dilute hydrochloric acid and acid ammonium oxalate as extractants for some heavy metals from Nile River sediments

The suitability of a 0.5 M HCl solution for extraction of Fe, Mn, Cd, Co, Cu, Pb, and Zn from Nile River sediments was evaluated by comparing its effectiveness with that of conventional acid ammonium oxalate (Tamm's solution) and aqua regia extraction solutions. The present study has shown that although the extraction data indicate that both 0.5 M HCl and acid ammonium oxalate solutions are able to extract heavy metals simultaneously from the adsorbed, organic, and precipitated phases of Nile sediments, the 0.5 M HCl solution is preferred. It provides a rapid, reliable, and inexpensive method of measuring environmentally mobile metal concentrations in the aquatic sediments. From an analytical chemistry point of view, the 0.5 M HCl extracts do not clog the atomizer of the spectrophotometer. Extraction with dilute HCl solution obviates the need to use chemicals, some of which are toxic or not available readily as a high-purity grade. A standard extraction method should be relatively simple, to conduct a routine analysis of large numbers of sediment samples, yet at the same time it should provide sufficient information for assessment of the environmental impact of particulate metals. Therefore, extraction with 0.5 M HCl solution is very suitable for heavy-metal pollution monitoring in the Nile River     

Assessment of metals in soil extracts and their uptake and movement within Tamarix nilotica at Lake Nasser banks,Egypt

This study aims to determine heavy-metal levels in soil from the banks of Lake Nasser, the ability of Tamarix nilotica to accumulate such metals from soil and hence its potential for phytoextraction. Soil and Tamarix samples were collected from the banks of four bights around Lake Nasser and analysed for Fe, Mn, Ca, Mg, Cr, Cu, Ni, Zn, Cd and Pb by atomic absorption spectrometry, whereas Na and K were measured by atomic emission spectrophotometry. Three different methods of extraction were used for the soil samples. Lead, copper and zinc were equally distributed between the exchangeable phase and Fe/Mn oxide-bound form, while other measured metals were mainly present in the Fe/Mn oxide fraction. With the exception of iron, all metals studied showed total concentrations within the geochemical background values. T. nilotica exhibited elevated concentrations of Na (36.2–48.5?mg?g^?1) and K (2.74–4.33?mg?g^?1) in stems, and relatively high concentrations of Pb, Cd and Co (0.39–1.03?µg?g^?1, 0.24–1.3?µg?g^?1 and 1.94–5.3?µg?g^?1, respectively) are found in plant leaves. Bioaccumulation factors of Na and K (9.3 and 12.63, respectively) were high in T. nilotica stems. While the bioaccumulation of Pb, Cd, Co and Ni (2870.1, 2035.4, 10.5 and 5313.2, respectively) was high in plant leaves, Fe, Mn, Ca and Mg were accumulated relatively equally in plant stems and leaves. T. nilotica was found to secrete high amounts of Na, Ca and K, in addition to small amounts of all accumulated metals except Cd and Cu. These secreted metals appeared as salt crystals (67.5% Na; 25.8% Ca; 5% Mg; 1.5% K and 0.16% trace and minor elements) on the plant surface. The concentrations of all the metals studied in T. nilotica were higher than in the salt crystals. Statistical analysis of the database suggests bioaccumulation of these metals from soil to T. nilotica. This reflects the importance of using T. nilotica as a model in the phytoremediation process as an established environmental clean-up technology.     

Remobilization of selected metal ions from Nile sediment (Egypt) according to sequential extraction and metal–EDTA complex

River sediments are basic components of our environment, providing nutrients for living organisms and serving as sinks for deleterious chemical species. The metal contents may be remobilized and released back into waters with changes in environmental conditions, thus affecting living organisms and human activities. This paper aims to determine the effect of a synthetic anthropogenic chelating agent (EDTA) as industrial discharges on the remobilization of several metals (Cu, Zn, Cd, and Pb) in River Nile sediments (at Aswan and Mansoura cities) under different concentrations and pH values, and to investigate the influence of metal–EDTA complexes on this remobilization. For these purposes, sequential extraction and experiments on the effect of pH and metal EDTA complex were carried out on the two representative sediment samples south and north of the River Nile in Egypt. The results of sequential extraction show that most of metal contents present in the residual form (Cu, 11.36–72.34%; Pb, 29.64–66.67%; and Zn, 43.76–50.09% at Aswan and Mansoura, respectively). Non-residual fractions which may be available for the remobilization by EDTA represented anthropogenic (industrial, agriculture, and domestic discharges) and lithiopogenic (metals bound to Fe and Mn oxides) sources. A clear increase was detected for Cu and Zn remobilization from the increase in EDTA concentrations, in contrast, Cd independent of the EDTA concentration and slight influence on Pb content. The remobilization of metals as a function of pH exhibited. The metals were greatly remobilized under the complexing action of EDTA, showing that some of these elements were adsorbed on the sediments. The remobilization rate of metals was dependent upon the added metal–EDTA complex (with the exchange rate being in the order Ca–EDTA>Zn–EDTA>Cd–EDTA>Cu–EDTA>Pb–EDTA), due to the stability constant of the metal–EDTA complex. The results of these experiments showed that heavy metals are greatly remobilized under the complexing action of EDTA when it is present in excess, so all precautions should be taken to prevent any wastewater containing EDTA or any chelating agents discharging directly or indirectly via the River Nile stream because most EDTA remains in the aquatic phase. The ability of this portion to remobilize metals from sediments should be taken into account.     

Health effects associated with long-term occupational exposure of employees of a chlor-alkali plant to mercury

This study aimed to evaluate possible health effects associated with long-term occupational exposure to low levels of mercury vapors. Forty-six subjects exposed to mercury and 65 healthy unexposed employees were studied. The subjects were administered a questionnaire on experienced symptoms and underwent clinical examinations as well as routine biochemical tests. Atmospheric and urinary concentrations of mercury were measured, too. Environmental concentrations of mercury were estimated to be 3.97 ± 6.28 μg/m(3) and urinary concentrations of mercury in exposed and referent groups were 34.30 ± 26.77 and 10.15 ± 3.82 μg/dm(3), respectively. Additionally, symptoms such as somatic fatigue, anorexia, loss of memory, erethism, blurred vision and teeth problems were significantly more common among exposed individuals. These observations indicate that occupational exposure to mercury vapors, even at low levels, is likely to be associated with neurological and psychological symptoms.