Isolation and characterization of bacterial strains capable of growing on malathion and fenitrothion and the use of date syrup as an additional substrate

Four bacterial strains capable of growing on two organophosphorus pesticides (malathion and fenitrothion) were isolated from activated sludge. Among these isolates, the species Stenotrophomonas maltophilia was found to be capable of using fenitrothion as the sole carbon and nitrogen source, and malathion as the sole carbon source. There appear to be no similar reported findings. A crude juice of dates was tested as an additional carbon source for malathion degradation. The biodegradability was significantly enhanced with the supplementation of date juice. The degradation efficiency of the pesticide tested at a concentration of 60 mg/L reached the maximum value of 89% in the presence of date juice at 30 g/L reducing sugar. Statistical screening of four operating parameters (initial biomass concentration, aeration rate, agitation and temperature) for biomass growth and for malathion degradation by acclimated indigenous activated sludge was carried out using a fractional factorial design.     

Tunneling of Graphene Massive Dirac Fermions Through a Double Barrier

We study the tunneling of Dirac fermions in graphene through a double barrier potential. This is allowing the carriers to have an effective mass inside the barrier as generated by a lattice miss-match with the boron nitride substrate. The consequences of this gap opening on the transmission are investigated and the realization of resonant tunneling conditions is analyzed.     

Selective oxidation of propane over PMoV?M/α‐Al2O3 (M: Co,Fe, or Ni)

Alumina supported phosphovanodomolybdic acid and alumina supported phosphovanodomolybdic acid‐transition metal ions (M: Fe³⁺, Co²⁺, or Ni²⁺) were prepared by impregnation. The thermal decomposition, in situ at 400°C, of supported catalysts showed the formation of V₂O₅, P₂O₅, MoO₃ and MoO₃, CoMoO₄, (Mo_0.3V_0.7)₂O₅ phases, on the alumina surface, in the presence of H₄PMo₁₁VO₄₀/α‐Al₂O₃ and H₄PMo₁₁VO₄₀? Co/α‐Al₂O₃, respectively. The catalytic activity of alumina‐supported catalysts was evaluated in the reaction of propane oxidation at 380 and 400°C. The addition of transition metal increases the conversion and changes the reaction products distribution. The reaction conditions (temperature and propane/oxygen ratio) have also modified the behaviour of the studied catalysts.     

The methodology of self-controlled case series studies

The self-controlled case series method is increasingly being used in pharmacoepidemiology, particularly in vaccine safety studies. This method is typically used to evaluate the association between a transient exposure and an acute event, using only cases. We present both parametric and semiparametric models using a motivating example on MMR vaccine and bleeding disorders. We briefly describe approaches for interferent events and a sequential version of the method for prospective surveillance of drug safety. The efficiency of the self-controlled case series method is compared to the that of cohort and case control studies. Some further extensions, to long or indefinite exposures and to bivariate counts, are described.     

TLM method for thermal investigation of IGBT modules in PWM mode

The insulated gate bipolar transistor (IGBT) is popularly used in high power, high frequency power-electronic applications such as motor control and inverters. These applications require well designed thermal management system to ensure the protection of IGBTs. Choice simulation tools for accurate prediction of device power dissipation and junction temperature become important in achieving optimised designs.In this paper, thermal analysis of a 1200 A, 3.3 kV IGBT module was investigated and analysed using the three-dimensional transmission line matrix (3D-TLM) method. The results show a three-dimensional visualisation of self-heating phenomena in the device. Since the comparison TLM results with the analytical solutions do not exist for this IGBT module, we use the MSC.NASTRAN tool to find the similar range of the temperatures. Results are compared.Typically, IGBT is used in a three-phase inverter leg where the control signals are generated via PWM scheme so, the prediction of the temperature rise is important in the pulse operation conditions for the IGBT device. A view of the dynamic thermal temperature rise is obtained with 100 W-step pulse dissipation applied at IGBT chips. The temperature rises are calculated using TLM method during the PWM load cycles. Simulations give clear indications of the importance of the spreader material and are helpful in selecting the proper one.TLM has been successful in modelling heat diffusion problems and has proven to be efficient in terms of stability and complex geometry. The three-dimensional results show that method has a considerable potential in power devices thermal analysis and design.     

Unsteady three-dimensional numerical study of mass transfer in PEM fuel cell with spiral flow field

Bipolar plate design and its flow field shape have an important effect on the fuel cell performance. In this work, a FORTRAN program has been developed to investigate the effects of the channel width, the number of turns of the spiral channel and the flow direction on the reactants consumption in a proton exchange membrane fuel cell (PEMFC) with a spiral flow field design. The governing equations are discretized using the finite volume method in cylindrical coordinates. The results show that the channel-rib width ratio influences the cell performance; the higher ratio, the more important contact area between the channel and the GDL, the more reactants quantity seeped to the GDL and more uniform reactants distribution is. The increasing the spiral channel turns number improves the reactants distribution uniformity. The channel spiral shape engenders a centrifugal force which enhances the cell performances in the case when the reactants are injected from the external side of the spiral channel and ejected from its internal one.     

Reduced reference image quality assessment based on statistics in empirical mode decomposition domain

This paper deals with the image quality assessment (IQA) task using a natural image statistics approach. A reduced reference (RRIQA) measure based on the bidimensional empirical mode decomposition is introduced. First, we decompose both, reference and distorted images, into intrinsic mode functions (IMF) and then we use the generalized Gaussian density (GGD) to model IMF coefficients of the reference image. Finally, we measure the impairment of a distorted image by fitting error between the IMF coefficients histogram of the distorted image and the estimated IMF coefficients distribution of the reference image, using the Kullback–Leibler divergence (KLD). Furthermore, to predict the quality, we propose a new support vector machine-based (SVM) classification approach as an alternative to logistic function-based regression. In order to validate the proposed measure, three benchmark datasets are involved in our experiments. Results demonstrate that the proposed metric compare favorably with alternative solutions for a wide range of degradation encountered in practical situations.     

The feasibility of new design of hybrid photovoltaic-thermal system – a theoretical approach

Hybrid photovoltaic thermal (PVT) collectors have been evaluated according to the physical features of commercial photovoltaic (PV) cells; therefore, their commercial application is limited. The Tedlar collector has good electrical insulating properties, resulting in reduction in electrical efficiency. A researcher found that a glazed PVT system without Tedlar was the best among others, showing a significant increase in the overall efficiency. Inspired by this finding, we thought to study, for the first time, the feasibility of a new PVT that has been built by modifying a commercial PV panel and retrofitting it with the integration of two tubes in glass above the PV cell pasted on a thin metal ribbon before PV encapsulation. A heat transfer modelling/simulation in 3D was performed using COMSOL Multiphysics software.

The results show that under the no-cooling situation, the PV cell temperature reaches 74.87°C and the electrical power dropped significantly to 0.113 for electrical efficiency of 0.15 at the reference conditions. The water flow velocity is determined so that the cell can be effectively cooled. The cell temperature variation reaches to 45.9°C for a flow velocity of 0.5m/s, an irradiation of 1000W/m² and ambient temperature equal to 20.15°C.