Biopreservation of hamburgers by essential oil of Zataria multiflora

Hamburgers with high nutrient supply and a loosely-packed structure present favourable conditions for microbial growth. In this study, the chemical composition and antimicrobial activity of the essential oil of Zataria multiflora and its potential application as a natural preservative in reducing the indigenous microbial population of hamburgers were investigated. Carvacrol, thymol and linalool were found to be the most abundant constituents of the essential oil using GC-MS analysis. The essential oil exhibited strong antibacterial activity against Gram-positive and Gram-negative bacteria. Addition of Z. multiflora essential oil in concentrations higher than MIC values influenced the microbial population of hamburgers stored at 25°C, 4°C and -12°C. The significant results of this study are our observations that the use of Z. multiflora essential oil at 0.05% v/w increases the time needed for the natural microflora of hamburgers to reach concentrations able to produce a perceivable spoilage at refrigerator and room temperatures without any inverse effect on their sensory attributes. Freezing of essential oil-treated hamburgers may also reduce the risk of diseases associated with consumption of under-cooked hamburgers through significant microbial reduction by more than 3 log.     

Breakdown voltage improvement of LDMOSs by charge balancing: An inserted P-layer in trench oxide (IPT-LDMOS)

For the first time, the novel inserted P-layer in trench oxide of LDMOS structure (IPT-LDMOS) is proposed in which a trench oxide with inserted P-layer is considered in the drift region to improve the breakdown voltage. Our simulation with two dimensional ALTAS simulator shows that by determining the optimum doping concentration of the P-layer, the charges of the N-drift and P-layer regions would be balanced. Therefore, complete depletion at the breakdown voltage in the drift region happens. Also, electric field in the IPT-LDMOS is modified by producing additional peaks which decrease the common peaks near the drain and source junctions.     

A method based on meshless approach for the numerical solution of the two‐space dimensional hyperbolic telegraph equation

In the current article, we investigate the RBF solution of second‐order two‐space dimensional linear hyperbolic telegraph equation. For this purpose, we use a combination of boundary knot method (BKM) and analog equation method (AEM). The BKM is a meshfree, boundary‐only and integration‐free technique. The BKM is an alternative to the method of fundamental solution to avoid the fictitious boundary and to deal with low accuracy, singular integration and mesh generation. Also, on the basis of the AEM, the governing operator is substituted by an equivalent nonhomogeneous linear one with known fundamental solution under the same boundary conditions. Finally, several numerical results and discussions are demonstrated to show the accuracy and efficiency of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.     

A meshless based numerical technique for traveling solitary wave solution of Boussinesq equation

In this paper, we employ the boundary-only meshfree method to find out numerical solution of the classical Boussinesq equation in one dimension. The proposed method in the current paper is a combination of boundary knot method and meshless analog equation method. The boundary knot technique is an integration free, boundary-only, meshless method which is used to avoid the known disadvantages of the method of fundamental solution. Also, we use the meshless analog equation method to replace the nonlinear governing equation with an equivalent nonhomogeneous linear equation. A predictor-corrector scheme is proposed to solve the resulted differential equation of the collocation. The numerical results and conclusions are obtained for both the ‘good’ and the ‘bad’ Boussinesq equations.     

Minimum flow problem on network flows with time-varying bounds

In this paper, we consider the minimum flow problem on network flows in which the lower arc capacities vary with time. We will show that this problem for set {0, 1, … , T} of time points can be solved by at most n minimum flow computations, by combining of preflow-pull algorithm and reoptimization techniques (no matter how many values of T are given). Running time of the presented algorithm is O(n²m).     

Essential normality for certain finite linear combinations of linear-fractional composition operators on the Hardy space H 2

In 1999 Nina Zorboska and in 2003 P. S.Bourdon, D. Levi, S.K.Narayan and J.H. Shapiro investigated the essentially normal composition operator ${C_\varphi }$ , when φ is a linear-fractional self-map of D. In this paper first, we investigate the essential normality problem for the operator T _w ${C_\varphi }$ on the Hardy space H ², where w is a bounded measurable function on ?D which is continuous at each point of F(φ), φ ∈ S(2), and T _w is the Toeplitz operator with symbol w. Then we use these results and characterize the essentially normal finite linear combinations of certain linear-fractional composition operators on H ².     

The numerical solution of the non-linear integro-differential equations based on the meshless method

This article investigates the numerical solution of the nonlinear integro-differential equations. The numerical scheme developed in the current paper is based on the moving least square method. The moving least square methodology is an effective technique for the approximation of an unknown function by using a set of disordered data. It consists of a local weighted least square fitting, valid on a small neighborhood of a point and only based on the information provided by its n closet points. Hence the method is a meshless method and does not need any background mesh or cell structures. The error analysis of the proposed method is provided. The validity and efficiency of the new method are demonstrated through several tests.     

An efficient one‐pot synthesis of a new heterocyclic system with high‐fluorescent properties

Nucleophilic substitution of hydrogen in nitro derivative of imidazo[1,2‐a]pyridine has been used as a key step in the one‐pot synthesis of a new highly fluorescent heterocyclic system pyrido [1″,2″:1′,2′]imidazo[4′,5′:5,6]pyrido[2,3‐b]indole. J. Heterocyclic Chem., (2012).     

Fabrication of Ti2SnC-MAX Phase Blended PES Membranes with Improved Hydrophilicity and Antifouling Properties for Oil/Water Separation

In this research work, the Ti₂SnC MAX phase (MP) was synthesized via the reactive sintering procedure. The layered and crystalline structure of this MP was verified by SEM, HRTEM, and XRD analyses. This nano-additive was used for improvement of different features of the polyethersulfone (PES) polymeric membranes. The blended membranes containing diverse quantities of the MP (0–1 wt%) were fabricated by a non-solvent-induced phase inversion method. The asymmetric structure of the membranes with small holes in the top layer and coarse finger-like holes and macro-voids in the sublayer was observed by applying SEM analysis. The improvement of the membrane’s hydrophilicity was verified via reducing the contact angle of the membranes from 63.38° to 49.77° (for bare and optimum membranes, respectively). Additionally, in the presence of 0.5 wt% MP, the pure water flux increased from 286 h to 355 L/m² h. The average roughness of this membrane increased in comparison with the bare membrane, which shows the increase in the filtration-available area. The high separation efficiency of the oil/water emulsion (80%) with an improved flux recovery ratio of 65% was illustrated by the optimum blended membrane.