Constraint structure in modified Faddeev-Jackiw method

We show that in modified Faddeev-Jackiw formalism, first and second class constraints appear at each level, and the whole constraint structure is in exact correspondence with level by level method of Dirac formalism.Comment: 11 pages, No figure

Spectral beam splitting for solar collectors : a photovoltaic-thermal receiver for linear concentrators

There is an unprecedented need to transform energy production methods from fossil fuel based to renewable sources. Among these sources, wind and solar energy have gained significant momentum by cost reduction and system efficiency improvement. The cost of silicon PV cells has dropped from 76 dollars per watt in 1977 to below 30 cents per watt in 2015. Photovoltaic electricity has already reached grid parity in some countries including parts of the US and Australia. Solar energy is anticipated to be the world's largest power production method by 2050. However the transition won't be smooth and some challenges are perceived. Utility scale PV fields can generate cheap electricity but their penetration can be curtailed once they reach 10% of total electricity supply. This is due to the lack of cost effective electrical energy storage. Even ambitious battery cost reduction in the next few years doesn't seem to be able to tackle this issue in short term. Hence, there is a significant need for innovative solar thermal power generators to be combined with PV converters to take advantage of cheap PV electricity and cost effective thermal energy and storage concurrently. The stored thermal energy can be converted into electricity cost effectively when there is no PV output due to absence of solar radiation. Collectors that simultaneously capture sunlight with PV cells and a thermal collector are called PV-T collectors. Traditional PV-T collectors are made of a PV receiver coupled to a thermal fluid. Since commercial PV cells convert about 15-20% of the sunlight to electricity, the remainder of the light energy dissipates as heat in them. The dissipated heat can be collected by the thermal fluid and delivered as useful energy. For low temperature applications this can be a suitable method. For high temperature cases such as thermal power plants or industrial heat generators, the PV cells should be thermally decoupled from the thermal absorber because their efficiency and durability deteriorate at high temperatures. This can be achieved by employing spectral beam splitting between the PV cells and the thermal absorber. In this thesis, a new method for effective spectral beam splitting for high temperature, greater than 120 C, hybrid PV-T receivers for linear solar concentrators is introduced. For this purpose, direct absorption and spectral light filtering using selective thermal fluids and semiconductor doped glass have been employed to achieve a relatively cost effective design for such receivers. The receiver was built and tested on a parabolic trough which is the first scalable experimental spectral splitting PV-T receiver built and tested in the literature. The system achieved a 4% electrical conversion efficiency at about 120 degree C thermal output using silicon solar cells while keeping the cells operating at temperature below 60 degree C. A high level of thermal decoupling between the cells and the thermal absorber as well as an optical efficiency of over 60% was observed in the proposed system. Some recommendation for improving the systems' efficiency is also provided at the end of this work

Comparison of antibacterial activity of essential oils of Foeniculum vulgare Mill, Mentha arvensis and Mentha piperita against Streptococcus mutans

Background and aims: Tooth decay is one of the most common chronic diseases around the world and this problem is the result of variety of different bacteria. Streptococcus mutants is one of the most important bacteria which is related to this disease. Finding new effective antibacterial agents is an important area in bioscience for fighting and controlling bacterial infections. Essential oils are most important natural sources of antibacterial agents, particularly against drug-resistant bacteria. Methods: The aim of this study was to evaluate and compare the antibacterial activity of three essential oils Mentha arvensis, Mentha piperita and Foeniculum vulgare Mill against Streptococcus mutants. Disk diffusion method was carried out and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. Results: The results showed that all three essential oils have antibacterial activity against S. mutants. With a constant concentration of 100 µg/µl, the efficiency of Mentha piperita and then Foeniculum vulgare Mill was higher than the efficiency of Mentha arvensis at all 3 given time points (24, 48 and 72 hours). The most effective MIC and MBC were related to Streptococcus mutants using Foeniculum vulgare essential oil which were equal to 8.4 and 14.9 µg/ml, respectively. MIC and MBC for Mentha piperita essential oil were measured 10.5 and 16.3 µg/ml, respectively. Conclusion: The Essential oils used in present study with different components showed antibacterial activity and therefore they can be used as new antibacterial substances

Anaerobic Membrane Bioreactor (AnMBR) for the Removal of Dyes from Water and Wastewater: Progress, Challenges, and Future Perspectives

The presence of dyes in aquatic environments can have harmful effects on aquatic life, including inhibiting photosynthesis, decreasing dissolved oxygen levels, and altering the behavior and reproductive patterns of aquatic organisms. In the initial phase of this review study, our aim was to examine the categories and properties of dyes as well as the impact of their toxicity on aquatic environments. Azo, phthalocyanine, and xanthene are among the most frequently utilized dyes, almost 70–80% of used dyes, in industrial processes and have been identified as some of the most commonly occurring dyes in water bodies. Apart from that, the toxicity effects of dyes on aquatic ecosystems were discussed. Toxicity testing relies heavily on two key measures: the LC50 (half-lethal concentration) and EC50 (half-maximal effective concentration). In a recent study, microalgae exposed to Congo Red displayed a minimum EC50 of 4.8 mg/L, while fish exposed to Disperse Yellow 7 exhibited a minimum LC50 of 0.01 mg/L. Anaerobic membrane bioreactors (AnMBRs) are a promising method for removing dyes from water bodies. In the second stage of the study, the effectiveness of different AnMBRs in removing dyes was evaluated. Hybrid AnMBRs and AnMBRs with innovative designs have shown the capacity to eliminate dyes completely, reaching up to 100%. Proteobacteria, Firmicutes, and Bacteroidetes were found to be the dominant bacterial phyla in AnMBRs applied for dye treatment. However, fouling has been identified as a significant drawback of AnMBRs, and innovative designs and techniques are required to address this issue in the future.</jats:p

Treatment of landfill leachate with different techniques: An overview

Landfill leachate is characterised by high chemical and biological oxygen demand and generally consists of undesirable substances such as organic and inorganic contaminants. Landfill leachate may differ depending on the content and age of landfill contents, the degradation procedure, climate and hydrological conditions. We aimed to explain the characteristics of landfill leachate and define the practicality of using different techniques for treating landfill leachate. Different treatments comprising biological methods (e.g. bioreactors, bioremediation and phytoremediation) and physicochemical approaches (e.g. advanced oxidation processes, adsorption, coagulation/ flocculation and membrane filtration) were investigated in this study. Membrane bioreactors and integrated biological techniques, including integrated anaerobic ammonium oxidation and nitrification/denitrification processes, have demonstrated high performance in ammonia and nitrogen elimination, with a removal effectiveness of more than 90%. Moreover, improved elimination efficiency for suspended solids and turbidity has been achieved by coagulation/ flocculation techniques. In addition, improved elimination of metals can be attained by combining different treatment techniques, with a removal effectiveness of 40–100%. Furthermore, combined treatment techniques for treating landfill leachate, owing to its high chemical oxygen demand and concentrations of ammonia and low biodegradability, have been reported with good performance. However, further study is necessary to enhance treatment methods to achieve maximum removal efficiency

Hepatitis B Virus Genotyping Among Chronic Hepatitis B Individuals With Resistance to Lamivudine in Shahrekord, Iran

Background: Hepatitis B infection, caused by hepatitis B Virus (HBV), is one of the major global public health problems. Hepatitis B Virus genotypes appear to show varying geographic distribution with possible pathogenic and therapeutic differences. Knowledge of HBV genotypes is very important for clinical treatment. Lamivudine is a nucleoside analogue that is clinically used to treat chronic hepatitis B infection. However, the main problem with the application of lamivudine is the development of viral resistance to the treatment with this anti viral drug. Besides, it has been suggested that lamivudine-resistant HBV may be genotype dependent. However, HBV genotype distribution and the biological relevance in this region are poorly understood. Objectives: The current study aimed to determine hepatitis B genotypes and their correlation with lamivudine-resistant HBV frequency among patients with chronic hepatitis B from Shahrekord, Iran. Methods and Materials: Hepatitis B virus DNA was detected by conventional PCR in some of the serum samples obtained from HBsAg-positive Chronic Hepatitis B (CHB) patients who were referred to Health Centers of Shahrekord for routine monitoring of the disease. Subsequently, using real-time PCR, the DNA samples were used for genotyping and analysis of resistance to lamivudine. Results: The DNA was detected in 23 out of 116 (19.82%) of the studied samples. Genotypes D and C were found in 17 out of 23 (73.9%), and in 6 out of 23 (26.1%) of the samples, respectively. To the authors' best knowledge, the current study is the first report on isolation of Genotype C from Iran. Two out of 17 (11.76%), and 6 out of 6 (100%) of genotypes D and C were resistant to lamivudine, respectively. Resistance to this drug was significantly different between genotypes C and D (P < 0.001). Conclusions: In addition to genotype D, other lamivudine resistant hepatitis B genotypes might be distributed in Iran

Contaminant Removal from Wastewater by Microalgal Photobioreactors and Modeling by Artificial Neural Network

The potential of microalgal photobioreactors in removing total ammonia nitrogen (TAN), chemical oxygen demand (COD), caffeine (CAF), and N,N-diethyl-m-toluamide (DEET) from synthetic wastewater was studied. Chlorella vulgaris achieved maximum removal of 62.2% TAN, 52.8% COD, 62.7% CAF, and 51.8% DEET. By mixing C. vulgaris with activated sludge, the photobioreactor showed better performance, removing 82.3% TAN, 67.7% COD, 85.7% CAF, and 73.3% DEET. Proteobacteria, Bacteroidetes, and Chloroflexi were identified as the dominant phyla in the activated sludge. The processes were then optimized by the artificial neural network (ANN). High R2 values (>0.99) and low mean squared errors demonstrated that ANN could optimize the reactors’ performance. The toxicity testing showed that high concentrations of contaminants (>10 mg/L) and long contact time (>48 h) reduced the chlorophyll and protein contents in microalgae. Overall, a green technology for wastewater treatment using microalgae and bacteria consortium has demonstrated its high potentials in sustainable management of water resources.</jats:p