A Shape‐Adaptive,Antibacterial‐Coating of Immobilized Quaternary‐Ammonium Compounds Tethered on Hyperbranched Polyurea and its Mechanism of Action

Quaternary‐ammonium‐compounds are potent cationic antimicrobials used in everyday consumer products. Surface‐immobilized, quaternary‐ammonium‐compounds create an antimicrobial contact‐killing coating. We describe the preparation of a shape‐adaptive, contact‐killing coating by tethering quaternary‐ammonium‐compounds onto hyperbranched polyurea coatings, able to kill adhering bacteria by partially enveloping them. Even after extensive washing, coatings caused high contact‐killing of Staphylococcus epidermidis, both in culture‐based assays and through confocal‐laser‐scanning‐microscopic examination of the membrane‐damage of adhering bacteria. In culture‐based assays, at a challenge of 1600 CFU/cm², contact‐killing was >99.99%. The working‐mechanism of dissolved quaternary‐ammonium‐compounds is based on their interdigitation in bacterial membranes, but it is difficult to envisage how immobilized quaternary‐ammonium‐molecules can exert such a mechanism of action. Staphylococcal adhesion forces to hyperbranched quaternary‐ammonium coatings were extremely high, indicating that quaternary‐ammonium‐molecules on hyperbranched polyurea partially envelope adhering bacteria upon contact. These lethally strong adhesion forces upon adhering bacteria then cause removal of membrane lipids and eventually lead to bacterial death.     

Preparation of hard coatings by ion beam methods

The activated growth of surface coatings under the influence of impinging ionized species has been investigated by beam techniques operating in high vacuum. A brief survey of the operating parameters using one or several beam bundles of ions or neutrals is given. Some results and problems are discussed in connection with the following processes: (1) nitriding of iron by low energy ion bombardment; (2) dual beam synthesis of silicon nitride and of hard carbon; (3) preparation of chromium-carbon and of hard carbon layers by ion beam plating from organic vapours. It is concluded that beam techniques can contribute to a better understanding of activated film growth at high rates of deposition. Moreover, ion beam methods offer interesting prospects for the preparation of special layer structures, particularly unusual film phases such as the hard i-carbon.     

The optimisation of extraction of antioxidants from potato peel by pressurised liquids

Response Surface Methodology was used to optimise the solid–liquid extraction and Pressurised Liquid Extraction of polyphenols from industrially generated potato peel. Efficiency of extraction was optimised by measuring antioxidant activity, phenol content and the level of caffeic acid. Conditions for optimal antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay were 75% ethanol, 80 °C and 22 min with solid–liquid extraction, resulting in an optimum activity of 352 mg Trolox Equivalents/100 g DW potato peel. In comparison, the use of Pressurised Liquid Extraction resulted in an optimum activity of 339 mg Trolox Equivalents/100 g DW potato peel at 70% ethanol and 125 °C. Therefore the use of Pressurised Liquid Extraction did not enhance extraction in comparison to solid–liquid extracts, but using aqueous ethanol as extraction solvent recovered a higher level of polyphenols than when using 100% methanol.     

Review of Pathological anxiety: Emotional processing in etiology and treatment.

Reviews the book, Pathological anxiety: Emotional processing in etiology and treatment edited by Barbara Olasov Rothbaum (see record 2005-16244-000). This book is a tribute to the work of Edna B. Foa whose model of emotional processing has had a profound impact on the understanding and treatment of individuals with pathological anxiety. The first section of the book provides a series of chapters on theoretical conceptualizations of various anxiety disorders stemming from emotional processing theory. The second section of the book overviews assessment and treatment strategies stemming from emotional processing theory, across a spectrum of specific anxiety disorders. This book also contains chapters on unique clinical applications of emotional processing theory. Through its foundational focus on defining and explicating the importance of principles as outlined in emotional processing theory, this book's significance to the future of psychological treatments of anxiety is clear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constitution and Crystallography of Thin Thermal-Oxide Layers on varepsilon -Fe2N1-x: A HREM Investigation

Oxide layers formed on varepsilon -Fe₂N_1-x wereinvestigated with X-ray photoelectron spectroscopy, X-ray diffraction, andin particular with high-resolution transmission electron microscopy. Priorto oxidation, the varepsilon -Fe₂N_1-x substrates wereeither exposed to air at room temperature, or subjected to asputter-cleaning pretreatment, or to a sputter cleaning with an additionalannealing pretreatment. The samples were oxidized at 400 or 573 K in pureO₂ at 8.0x10^-2 Pa or at 10⁵Pa. All oxide films contained magnetite ( -Fe₂N_1-x)as a major constituent. On samples that were sputter-cleaned and annealedprior to oxidation as well as on the air-exposed sample, wüstite,(Fe₁-O) was observed between the Fe₃O₄and -Fe₂N_1-x. On the basis of HREM, thiswüstite phase, which on -Fe does not develop at temperaturesbelow 843 K, was concluded to have a preferred crystallographic orientationwith respect to the supporting -Fe₂N_1-x grains. Nospecific orientation relation was found between Fe₃O₄ and -Fe₂N_1-x. The implications of the developmentof Fe_1-O for the evolution of the oxide film arediscussed.     

Multi-component lattice gas diffusion

In this paper, diffusional transport of multi-component mixtures within the framework of a three-dimensional lattice gas is studied using dynamic Monte Carlo simulations. The mobile species, instantaneously hopping from one site to another, are assumed to have no mutual interactions, other than the usual ‘hard core’ interactions. Most strikingly, percolation phenomena occur for multi-component mixtures with significant differences in mobility. These greatly reduce the flux of the mobile component and cause failure of the standard macroscopic theories, including, e.g., the Maxwell-Stefan theory. Furthermore, we demonstrate that the well-known correlation effect disappears for systems in which gradients in the vacancy concentration are present. For systems in which co-operative displacements of two or more molecules are allowed to occur the effect of correlation between successive jumps vanishes, while the plot of the mobility versus occupancy shows a maximum. This intricate relation between mobility and occupancy again complicates the use of standard theories for describing mass transport.     

Novel ultrafine Fe(C) precipitates strengthen transformation-induced-plasticity steel

A transmission electron microscopy study was conducted on nanoprecipitates formed in Ti microalloyed transformation-induced-plasticity-assisted steels, revealing the presence of Ti(N), Ti₂CS and a novel type of ultra-fine Fe(C) precipitate. The matrix/precipitate orientation relationships, sizes and shapes were investigated in detail. The ultrafine, disc-shaped Fe(C) precipitates have sizes of 2–5 nm and possess a hexagonal close packed crystal structure with lattice parameters a = 5.73 ± 0.05 Å, c = 12.06 ± 0.05 Å. They are in a well-defined Pitsch–Schrader orientation relationship with the basal plane of the precipitate parallel to the [1 1 0] habit plane of the surrounding body-centred-cubic ferritic matrix. Detailed analysis of precipitate distribution, orientation relationship, lattice mismatch and inter-particle spacing suggests that these ultrafine precipitates contribute considerably to the strengthening of these steels.     

Economics of the oxidative coupling of methane as an add-on unit for naphtha cracking

The feasibility of methane coupling as an add-on unit to a naphtha cracker was studied. The existing cold box was used for separation of ethylene and unconverted methane, but arrangements were made for separation of the coupling by-products. The cracker's methane was used as a feedstock. The concept is technically and economically feasible at spring 1992 prices, provided the catalyst meets the assumed 30% conversion and 80% C₂ selectivity.     

An application of theN-strip method of integral relations for analyzing the flow around a circular cone

Summary The solution of sets of non-linear partial differential equations using the method of integral relations is considered. Emphasis is laid on the derivation of a generalN-strip approximation algorithm. In order to check the applicability of this algorithm a program has been written to obtain the solution of the flow field around a circular cone at incidence in supersonic flow. Using the method of Stone, the angle of attack has been taken into account up to the second order. Thus a comparison can be made with the results given by Kopal.The results show that theN-strip algorithm in the case studied is a very attractive method which leads straight-forward to results of high accuracy.Formerly National Aerospace Laboratory (NLR).     

Ion beam nitriding of high purity iron surfaces

Ion beam nitriding of iron by N₂⁺ ions of medium energy (1–10 keV) was investigated. This nitriding technique leads to the formation of layer structures quite similar to those obtained by other methods but compared with these the nitride layers obtained are pore free. Results consisting of the surface topography of the samples, the stages of nitride coverage, the formation of different nitrides and their precipitation depth as well as microhardness and electrochemical corrosive behaviour are presented and discussed.