In vitro evaluation of anti-pathogenic surface coating nanofluid,obtained by combining Fe3O4/C12 nanostructures and 2-((4-ethylphenoxy)methyl)-N-(substituted-phenylcarbamothioyl)-benzamides

In this paper, we report the design of a new nanofluid for anti-pathogenic surface coating. For this purpose, new 2-((4-ethylphenoxy)methyl)-N-(substituted-phenylcarbamothioyl)-benzamides were synthesized and used as an adsorption shell for Fe₃O₄/C₁₂ core/shell nanosized material. The functionalized specimens were tested by in vitro assays for their anti-biofilm properties and biocompatibility. The optimized catheter sections showed an improved resistance to Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 in vitro biofilm development, as demonstrated by the viable cell counts of biofilm-embedded bacterial cells and by scanning electron microscopy examination of the colonized surfaces. The nanofluid proved to be not cytotoxic and did not influence the eukaryotic cell cycle. These results could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with improved anti-biofilm properties.     

The effect of temperature and annealing on the phase composition, molecular mobility and the thickness of domains in high-density polyethylene

Molecular mobility, the thickness of domains and the amount of rigid, semi-rigid, and soft fractions of high-density polyethylene (HDPE) were characterized as a function of temperature and annealing time using time- and frequency-domains proton solid-state NMR. These experiments established the temperature range for which the largest differences are observed in molecular mobility in crystalline phase, semi-rigid crystal-amorphous interface, and soft fraction of the amorphous phase allowing accurate determination of the phase composition and the thickness of these domains. The domain thickness, which was determined by NMR, is in good agreement to those measured by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) on the same sample. Changes in molecular mobility in the amorphous phase upon increasing temperature and annealing are discussed. It is shown that annealing is accompanied by structural reorganizations in the amorphous layer adjacent to the lamella surface causing a continuous shift of the interface towards the inner part of the amorphous regions and thus reducing the thickness of the amorphous layer. A recently introduced method was used for measuring the thickness of domains by a spin-diffusion NMR experiment with a double-quantum dipolar filter. The temperature dependence of the spin diffusivities is reported for the three phases of HDPE. For the first time results of spin-diffusion experiment performed by time-domain low-field NMR and frequency-domain high-field NMR are compared.     

Theoretical Analysis of Pulsed Photoacoustic Effect in Solids

This article presents a one-dimensional theory of a photoacoustic cell, working in the pulse regime. A four-layer system with elements of finite thickness has been assumed to represent consecutive parts of the photoacoustic cell. A parabolic heat equation with an instantaneous, bulk heat source has been solved using the Fourier transform of spatial coordinates. The theory allows one to assume that a heat source is existing in every part of the system and that an arbitrary time profile of the initial pulse is applied. Consequently, the system can be treated as an arbitrary photothermic or photoacoustic one-dimensional system. As a result, one obtains temperature profiles in the entire system at any time instant after its excitation with a light pulse. The gas-pressure evolution is dependent on the thermal and optical properties of the sample, the cell geometry, and duration and shape of the initial pulse.     

Acinetobacter baumannii K106 and K112: Two Structurally and Genetically Related 6-Deoxy-l-talose-Containing Capsular Polysaccharides

Whole genome sequences of two Acinetobacter baumannii clinical isolates, 48-1789 and MAR24, revealed that they carry the KL106 and KL112 capsular polysaccharide (CPS) biosynthesis gene clusters, respectively, at the chromosomal K locus. The KL106 and KL112 gene clusters are related to the previously described KL11 and KL83 gene clusters, sharing genes for the synthesis of l-rhamnose (l-Rhap) and 6-deoxy-l-talose (l-6dTalp). CPS material isolated from 48-1789 and MAR24 was studied by sugar analysis and Smith degradation along with one- and two-dimensional 1H and 13C NMR spectroscopy. The structures of K106 and K112 oligosaccharide repeats (K units) l-6dTalp-(1→3)-D-GlcpNAc tetrasaccharide fragment share the responsible genes in the respective gene clusters. The K106 and K83 CPSs also have the same linkage between K units. The KL112 cluster includes an additional glycosyltransferase gene, Gtr183, and the K112 unit includes α l-Rhap side chain that is not found in the K106 structure. K112 further differs in the linkage between K units formed by the Wzy polymerase, and a different wzy gene is found in KL112. However, though both KL106 and KL112 share the atr8 acetyltransferase gene with KL83, only K83 is acetylated.     

Chemical applications of near-field scanning optical microscopy: Surface and near-surface chemical imaging with conventional near-field optical probes and externally illuminated chemically active ion sensors

Near-field optics using force sensing cantilevered optical fibers and micropipettes is used to investigate the chemical distribution of protein complexing dyes in chromosomes and the sensing and chemical imaging of surfaces and nearsurface regions. These results are put in the context of what presently can be considered as a broad picture of near-field optical chemical applications.     

Hydrothermal synthesis and characterization of some polycrystalline α-iron oxides

Hematite powders with distinct particle morphology were obtained by hydrothermal synthesis, in the temperature range of 160–300°C. Goethite and ferric hydroxide precursors prepared by precipitation and oxidation under different reaction conditions were used. The hydrothermal reactions were developed in aqueous neutral or alkaline suspensions. In some cases additives were used as growth shape agents. By changing and controlling the reaction parameters, oxide powders with desired particle shapes (acicular, polyhedral, platelike, spherical, hexagonal) and dimensions (0.1–30 μm) were obtained. The characteristics of hematite powders, green bodies and sintered compacts were investigated by X-ray diffraction, electron microscopy, transmission and electron conversion Mössbauer spectroscopy. The correlation between the preparation conditions and the properties of the obtained iron oxides is discussed together with their potential applications. ©     

The Politics of Textiles in the Romanian Contemporary Art Scene

This paper explores the means and ends to which textiles are employed by contemporary Romanian artists in their intermedial practices. The history of textile arts in Romania’s cultural-political sphere has received little academic attention in studies dedicated to recent history. The argument put forth is that tapestry, rugs, and other textiles associated in the past with undervalued housework or folk art—and ranked as a lower form of artistry in the artistic hierarchy—are reinvested with political, critical, and mnemonic meanings. The first section addresses the convoluted relationship between textile arts and Romania’s communist era during Nicolae Ceau?escu’s regime by highlighting the ways in which the authoritarian state supervised and controlled the production of so-called folk textile art to political ends. The next sections elaborate on the artistic production of Geta Br?tescu, Ana Lupa?, and Ion Grigorescu, all of whom produced contemporary textile art—often derogatively called “applied art”—whose meanings and purposes eluded the official requirements of national folk art. In the last section the paper scrutinizes the political, critical, and artistic comeback of textile arts as cultural memory since the fall of the communist regime in 1989.     

Uncertainty quantification models for micro‐scale squeeze‐film damping

Two squeeze‐film gas damping models are proposed to quantify uncertainties associated with the gap size and the ambient pressure. Modeling of gas damping has become a subject of increased interest in recent years due to its importance in micro‐electro‐mechanical systems (MEMS). In addition to the need for gas damping models for design of MEMS with movable micro‐structures, knowledge of parameter dependence in gas damping contributes to the understanding of device‐level reliability. In this work, two damping models quantifying the uncertainty in parameters are generated based on rarefied flow simulations. One is a generalized polynomial chaos (gPC) model, which is a general strategy for uncertainty quantification, and the other is a compact model developed specifically for this problem in an early work. Convergence and statistical analysis have been conducted to verify both models. By taking the gap size and ambient pressure as random fields with known probability distribution functions (PDF), the output PDF for the damping coefficient can be obtained. The first four central moments are used in comparisons of the resulting non‐parametric distributions. A good agreement has been found, within 1%, for the relative difference for damping coefficient mean values. In study of geometric uncertainty, it is found that the average damping coefficient can deviate up to 13% from the damping coefficient corresponding to the average gap size. The difference is significant at the nonlinear region where the flow is in slip or transitional rarefied regimes. Copyright © 2010 John Wiley & Sons, Ltd.     

Hydrothermal-Freeze-Casting of Poly(amidoamine)-Modified Graphene Aerogels towards CO2 Adsorption

This article presents novel poly(amidoamine) (PAMAM) dendrimer-modified with partially-reduced graphene oxide (rGO) aerogels, obtained using the combined solvothermal synthesis-freeze-casting approach. The properties of modified aerogels are investigated with varying synthesis conditions, such as dendrimer generation (G), GO:PAMAM wt. ratio, solvothermal temperature, and freeze-casting rate. Scanning electron microscopy, Fourier Transform Infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy are employed to characterize the aerogels. The results indicate a strong correlation of the synthesis conditions with N content, N/C ratio, and nitrogen contributions in the modified aerogels. Our results show that the best CO₂ adsorption performance was exhibited by the aerogels modified with higher generation (G7) dendrimer at low GO:PAMAM ratio as 2:0.1 mg mL⁻¹ and obtained at higher solvothermal temperature and freeze-casting in liquid nitrogen. The enclosed results are indicative of a viable approach to modify graphene aerogels towards improving the CO₂ capture.