Effects of Zataria multiflora boiss essential oil,ultraviolet radiation and their combination on Listeria monocytogenes biofilm in a simulated industrial model

The objective of this study was to investigate the inhibitory effect of Zataria multiflora boiss essential oils (ZEOs), ultraviolet (UV) radiation and their combination against Listeria monocytogenes biofilm in a simulated industrial model (SIM). The effect of minimal inhibitory concentration (MIC) and sub‐MIC concentration of ZEOs, different contact time of UV and their combination was evaluated in a SIM on 6‐ and 12‐day‐old L. monocytogenes biofilm. In a SIM, 0.3% ZEOs were adequate to completely eliminate 6‐ and 12‐day‐old biofilm grown on stainless steel coupons. The population of viable L. monocytogenes biofilm cells under a 15‐ to 45‐min contact time of UV treatment declined significantly at 6‐ and 12‐day‐old biofilm. The combined effect of ZEO and UV showed antagonist effects. These findings indicated that in the single use, ZEO and UV revealed a suitable antilisteria biofilm activity, while combining them is not a promising method to remove listeria biofilms from stainless steel surfaces.     

New route for bromination of multiwalled carbon nanotubes under mild and efficient conditions

A short study on bromination of multiwalled carbon nanotubes (MWCNTs) through new and convenient methods was reported. Bromine (Br) is chemically attached on MWCNTs surfaces through electrophilic addition and radical reactions using N-Bromosuccinimide (NBS), NH₄NO₃/NBS and Br₂ under thermal and UV conditions. Functionalized CNTs with Bromine groups, were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), scanning electron microscopy and X-ray diffraction (XRD) methods.     

Design,Simulation and Construction of a Low-Density Fixed-Frequency Refleloctometer

Since some tokamaks such as Taban are currently working with low density plasma, a fixed frequency reflectometer system was designed and constructed to monitor plasma production within the vacuum vessel. In this paper, the detail of design, simulation and construction of the system is presented. Moreover, some experiments which have been made for the evaluation of the system performance is reported. The system consists of a circular waveguide-antenna to both transmit and receive the microwave as well as a fully integrated system for measuring the phase difference between transmitted and received signals. To make sure of the perfect performance of the constructed system, some experiments were conducted to individually evaluate system operation. In order to verify the obtained results, all the mentioned experiments were simulated using CST software and the simulation results were compared with those obtained from the experiments. Good agreements were observed between simulation and experimental results, implying the high reliability of the system operation. After approval of the system performance, the system was implemented in Taban Tokamak to monitor the plasma production. Using the reflectometer outputs, the plasma density was estimated.     

Six common errors cause dangerous mistakes in interpretation of electron micrographs

The highly complex techniques of electron microscopy made it bound to the sensitive and critical micrograph analysis. The accurately interpreted micrographs are of paramount values in basic investigations. Interpretation skills and quality of the micrographs are the two fundamental keys in accomplishment of these goals but there are many mistakes and errors that can happen during the sample preparation, sectioning, EM operation, and photo publishing. The mentioned mistakes and errors effect directly in the final result which is a micrograph and can lead the analyzer who can be a pathologist to an interpretation followed by serious danger for patient. Artifacts caused by any given stimuli expected to be bothersome for investigators. Even best qualified equipments can be regarded as source of artifact generation. In this article, seven serious errors in electron micrographs which usually occur in transmission electron microscopy are addressed.     

FePt/reduced graphene oxide composites for high capacity hydrogen storage

Here, reduced graphene oxide (rGO) was modified with iron and platinum nanoparticles by solvothermal method. The structural order and textural properties of the graphene based materials were studied by BET, TEM, XRD, TGA and XPS techniques. Hydrogen storage properties of GO, platinum loaded reduced graphene oxide (Pt-rGO), iron loaded reduced graphene oxide (Fe-rGO), and iron platinum loaded reduced graphene oxide (FePt-rGO) have been investigated in the pressure range of 0.05 to atmospheric pressure and at 77 and 87 K. This gives hydrogen adsorption capacities of about 1.2, 2.1, 1.9, and 2.7 wt% at 77 K for GO, Pt-rGO, Fe-rGO, and FePt-rGO, respectively. The isosteric heat of adsorption (Q_st) was investigated as a function of hydrogen uptake at 77 and 87 K over the pressure range of 0.05 to atmospheric pressure. The isosteric heat of adsorption for FePt-rGO (9.2 kJ/mol) was found to be higher than the isosteric heat of adsorption for GO (6.1 kJ/mol) indicating a favorable interaction between hydrogen and surface of the reduced graphene oxide.     

Optimization of Zn(O,S)/(Zn,Mg)O buffer layer in Cu(In,Ga)Se<Subscript>2</Subscript> based photovoltaic cells

Device modeling of CIGS based thin film solar cell with Zn(O,S)/(Zn,Mg)O buffer layer was simulated in order to find the optimum ratios of magnesium in (Zn_1?x,Mg_x)O and oxygen in Zn(O_y,S_1?y) which led to the optimized values of x = 0.1?0.25 and y = 0.5?0.6. When the oxygen content of Zn(O,S) was lower than 30 %, the recombination at Zn(O,S)/CIGS interface became prominent and J_SC was severely limited. It was found that the V_OC is approximately independent of magnesium content in (Zn,Mg)O and oxygen content in Zn(O,S) layers, and the efficiency is highly affected by the fill factor. Also studied were the effect of thicknesses of (Zn,Mg)O and Zn(O,S) layers while the x and y were set at x = 0.2 and y = 0.6. Our simulations show that the optimum range for thickness of the (Zn,Mg)O layer is from 70 to 100 nm, while it is 20–30 nm for the Zn(O,S) layer.