Activity of a dry mist-generated hydrogen peroxide disinfection system against methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii

Background: The aim of this study was to evaluate the activity of a dry mist-generated hydrogen peroxide (DMHP) system (Sterinis; Gloster Sante Europe, Labege cedex, France) against methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii. Methods: McFarland 0.5 suspensions of 2 test bacteria, either pure or containing 5% sterile serum, were prepared and inoculated onto sterile stainless steel disks. Each disk in a Petri dish - with the Petri dish cover either closed or open - was placed in different locations in an intensive care unit room. Quantitative cultures were performed after the cycle. Results: No growth occurred on the disks in the absence of a barrier, except 1 disk containing serum. Existence of a barrier, as a drawer or a covered Petri dish, caused failure in the disinfection activity. The mean reduction in initial log 10 bacterial count was lower for both of the test bacteria in presence of a barrier: 4.44- to 4.70-log 10 colony-forming units (cfu) decrease was observed in absence of a barrier, whereas 1.49- to 3.79-log 10 cfu decrease was observed in presence of a barrier. When the culture results were compared according to organic load content, the mean (±standard deviation) reduction of initial contamination in pure and in serum containing MRSA suspensions was 4.25 ± 1.20- and 3.34 ± 1.89-log 10 cfu, respectively. The mean (±standard deviation) reduction in pure and in serum containing A baumannii suspensions was 4.34 ± 0.89- and 3.87 ± 1.26-log 10 cfu, respectively. The differences were statistically significant (P <.001). Conclusion: Sterinis was capable of killing MRSA and A baumannii on open surfaces; however, it was not effective in closed or semiclosed areas. Presence of serum also caused failure in the disinfection activity of the system. Copyright © 2011 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved

Lignin: a biobased dielectric polymer for Organic Field Effect Transistors (OFETs)

Lignin is a biopolymer, recovered as a waste product of industrial pulping processes of lignocellulosic biomass. Lignin displays a complex structure, poor solubility in common solvents, broad distribution of molecular weight, and properties that depend on natural origin and isolation procedure [1]. This makes the lignin valorization a challenging point for chemists and materials scientists, especially in device fabrication where materials with regular and definite molecular structures are required [2]. In this communication, we present the structural and chemical-physical characterization of two kraft lignins, named L1 and L2, and we describe which structural characteristics will affect lignin efficiency in serving as an excellent gate dielectric polymer for OFET devices. Our promising results demonstrate the effectiveness of L1 and L2 as gate dielectric layers in pentacene or C60-based bottom gate top contacts OFET devices [3]. In addition, we present the solvent fractionation of L1 and L2 by Soxhlet or Kumagawa methods, supporting a deeper characterization of their chemical structure

Lignin: a potential renewable material candidate for organic devices

Lignin is one of the main constituents of lignocellulosic biomass. Lignin is recovered as a waste product of the cellulose industry, and it is an attractive feedstock for renewable chemicals and materials production. Nowadays, attention to lignin valorization into new chemicals and materials has increased.1 However, lignin possesses a complex chemical structure and variable properties depending on its natural origin and isolation procedure.2 Furthermore, lignin’s poor solubility in common solvents and broad distribution of molecular weight limit the use of lignin in devices. Indeed, devices fabrication requires materials with a highly regular and definite molecular structure.3 In this communication, we describe the structural and chemical-physical characterization of two kraft lignins, L1 and L2, and their thin film deposition to apply them as dielectric layers in organic field-effect transistor (OFETs) devices. Thanks to deposition from hydroalcoholic ammonia, we could achieve successfully smooth and semi-transparent lignin thin films. This enabled the use of L1 and L2 in pentacene or C60-based bottom gate top contacts OFET devices.4 In addition, we present the solvent fractionation of L1 and L2 by Soxhlet or Kumagawa methods, supporting a deeper characterization of their chemical structures

Lignin structural, chemical and physical characterization and dielectric performance in organic field-effect transistors

An organic field-effect transistor (OFET) is a field-effect transistor that uses semiconductive properties of organic materials. Dielectrics and semiconductors are the inner constituents of OFETs, mostly responsible for the success of the technology. The emerging necessity for safe, non-toxic, and ecologically sustainable organic electronics and bioelectronics, in opposition to the less sustainable inorganic counterparts, requires the use of green functional materials1 . In this perspective, we studied the use of lignin as dielectric layer in OFETs. Lignin is an abundant biopolymer synthesized by plants and a waste of diverse pulping processes. Lignin is rich in aromatic ring content. Its use in materials science is limited by the scarce knowledge on its structure, which depends also on its isolation method. In this work, we analyse the structural and chemical-physical characteristics of two commercially available kraft lignins, named L1 and L2, deriving from softwood by the kraft process, differing for the isolation process (acid or alkaline). First, we apply several molecular characterization techniques, such as ATR-FTIR, elemental analyses, GPC-HPLC, EGA MS, UV-Vis, 31P- and 13C-NMR spectroscopies to get insights into their different structures and their degree of molecular degradation, then we fractionate the two lignins to investigate the effects of solvent fractionation on the chemical structures and the impact of two different methods such as Soxhlet and Kumagawa extraction2 . Finally, we demonstrate their efficient application as gate dielectric in bottom-gate top-contacts organic field effect transistor (OFET) devices and how structural characteristics will affect their efficiency as gate dielectric polyme

Analysis and Design Optimization of Blunt Bodies In Hypersonic Flow

The purpose of this study is to model hypersonic flow around blunt body especially in atmospheric reentry of Earth. The more detailed model contains each energy transformation between each energy modes and all reactions. To simulate flow field region, thermal and chemical nonequilibrium must be considered all together. For the chemical nonequilibrium, species masses production of reactions must be characterized with suitable model. In this study, flow analysis based on the finite rate chemical reaction equations. Flow field region is assumed as continuum. Also flow is considered as inviscid and there is no diffusion. Computation of flow field is based on the axisymmetric Euler code. Coupled equations, chemical and thermal nonequilibrium equations are solved by using Newton's method. Jacobian matrices are calculated analytically. In the design part, aim is to obtain reduced pressure drag while keeping the body as blunt. Optimization results for various situations are represented

Analysis and Adjoint Design Optimization of Hypersonic Blunt Bodies

© 2014 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.The main purpose of this study is to analyze hypersonic flow field around the blunt bodies and to design of that bodies in order to obtain minimum pressure drag. Modeling of non-equilibrium must be done properly. In this study, non-equilibriums of thermal and chemical modes are considered. Translational and rotational energy modes are assumed that energy exchange between these modes is so fast. Vibrational and electronic energy terms are neglected. Therefore, one temperature is used to model thermo-chemical non-equilibrium. Flow field is assumed as inviscid and continuum region. Moreover, there is not diffusion. Thus, to model chemical non-equilibrium, finite rate chemistry can be used. For the thermal- nonequilibrium, enthalpy, entropy and specific heat constants are obtained from curve fitting methods. The coupled flow field equations are solved by using Newton’s methods. To solve Newton’s method, Jacobian matrices evaluation is required. In terms of convergence, Jacobian matrices are obtained by using analytical methods. At the design part, sensitivities are obtained by using adjoint design methods. The aim of design part is finding a hypersonic blunt geometry with minimum pressure drag while keeping the maximum temperature smaller than the baseline value

Aerothermodynamic Design Optimization in Hypersonic Flows

© 2013, American Institute of Aeronautics and Astronautics Inc. All rights reserved.The objective of this study is to develop a reliable and efficient design tool that can be used in hypersonic flows. The flow analysis is based on the axisymmetric Euler and the finite rate chemical reaction equations. These coupled equations are solved by using Newton’s method. The analytical and numerical methods are used to calculate Jacobian matrices. The effects of error in numerical Jacobians on the performance of flow and sensitivity analyses are studied. A gradient based numerical optimization is used. Sensitivities are calculated by using finite-difference, direct differentiation and adjoint methods. The objective of the design is to generate a hypersonic blunt geometry that produces the minimum pressure drag while keeping the maximum temperature smaller than the initial value. Bezier curves are used for geometry modification. The performance of the optimization method is demonstrated for different hypersonic flow conditions