Surface film formation by chemical vapor deposition of di-p-xylylene : ellipsometrical, atomic force microscopy, and x-ray studies

Thin and transparent poly(p-xylylene) (PPX) layers in the range 2-1550 nm have been prepared by means of chemical vapor deposition (CVD) via vapor-phase pyrolysis of the cyclic di-p-xylylene dimer. Ellipsometrical measurements are employed on those materials to study in detail the dependence of layer formation on sublimation temperature (80-140 °C) and deposition time (5-360 min). The layer growth rate on silicon wafers is found to be 0.3, 1.0, 6.3, and 11.8 mm/min at sublimation temperatures of 80, 100, 120, and 140 °C, respectively. The PPX layers are optically transparent in the investigated range of wavelengths from 190 to 1700 nm. Atomic force microscopy (AFM) studies show a surface roughness of 2-4 nm and larger values, 5-9 nm, at a high sublimation temperature of 140 °C or large deposition times tdc > 120 min. Wide angle X-ray diffraction (WAXD) experiments describe a monoclinic crystalline a-form with reflections (020) and (110) at 2¿Cu = 17.7 and 22.8°, respectively. Small angle X-ray scattering (SAXS) studies reveal a lamellar structure with a long period of 8.3 nm

Globally Abundant “ Candidatus Udaeobacter” Benefits from Release of Antibiotics in Soil and Potentially Performs Trace Gas Scavenging

Verrucomicrobia affiliated with “Candidatus Udaeobacter” belong to the most abundant soil bacteria worldwide. Although the synthesis of antibiotics presumably evolved in soil, and environmental pollution with antimicrobials increases, the impact of these complex molecules on “Ca. Udaeobacter” remains to be elucidated. In this study, we demonstrate that “Ca. Udaeobacter” representatives residing in grassland as well as forest soil ecosystems show multidrug resistance and even take advantage of antibiotics release. Soils treated with up to six different antibiotics exhibited a higher “Ca. Udaeobacter” abundance than corresponding controls after 3, 8, and 20 days of incubation. In this context, we provide evidence that “Ca. Udaeobacter” representatives may utilize nutrients which are released due to antibiotic-driven lysis of other soil microbes and thereby reduce energetically expensive synthesis of required biomolecules. Moreover, genomic analysis revealed the presence of genes conferring resistance to multiple classes of antibiotics and indicated that “Ca. Udaeobacter” representatives most likely oxidize the trace gas H2 to generate energy. This energy might be required for long-term persistence in terrestrial habitats, as already suggested for other dominant soil bacteria. Our study illustrates, for the first time, that globally abundant “Ca. Udaeobacter” benefits from release of antibiotics, which confers advantages over other soil bacteria and represents a so-far overlooked fundamental lifestyle feature of this poorly characterized verrucomicrobial genus. Furthermore, our study suggests that “Ca. Udaeobacter” representatives can utilize H2 as an alternative electron donor

Simulation of the stretch blow moulding process: from the modelling of the microstructure evolution to the end-use elastic properties of polyethylene terephthalate bottles

The original publication is available at www.springerlink.comThe whole stretch blow-moulding process of PET bottles is simulated at the usual process temperature in order to predict the elastic end-use properties of the bottles. An anisotropic viscoplastic constitutive law, coupled with microscopic variables, is dentified from uniaxial tensile tests performed at different strain rates and temperatures. The microstructure evolution is characterised by crystallinity measurements from interrupted tests and frozen samples. For each specimen tested, the Young modulus is measured at room temperature. Numerical simulations of the blow moulding process are run using the C-NEM method. A micromechanical modelling is post-processed after the simulation to predict the elastic properties. Predictions of Young modulus distributions in bottles are in agreement with the ones measured on blow-moulded bottles