Properties of silver nanostructure-coated PTFE and its biocompatibility

Silver nanolayers were sputtered on polytetrafluoroethylene (PTFE) and subsequently transformed into discrete nanoislands by thermal annealing. The Ag/PTFE composites prepared under different conditions were characterized by several complementary methods (goniometry, UV-visible spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy), and new data on the mechanism of Ag layer growth and Ag atom clustering under annealing were obtained. Biocompatibility of selected Ag/PTFE composites was studied in vitro using vascular smooth muscle cell (VSMC) cultures. Despite of the well-known inhibitory properties of silver nanostructures towards broad spectrum of bacterial strains and cells, it was found that very thin silver coating stimulates both adhesion and proliferation of VSMCs.     

Grafting of bovine serum albumin proteins on plasma-modified polymers for potential application in tissue engineering

In this work, an influence of bovine serum albumin proteins grafting on the surface properties of plasma-treated polyethylene and poly-l-lactic acid was studied. The interaction of the vascular smooth muscle cells with the modified polymer surface was determined. The surface properties were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, nano-LC-ESI-Q-TOF mass spectrometry, electrokinetic analysis, and goniometry. One of the motivations for this work is the idea that by the interaction of the cell with substrate surface, the proteins will form an interlayer between the cell and the substrate. It was proven that when interacting with the plasma-treated high-density polyethylene and poly-l-lactic acid, the bovine serum albumin protein is grafted on the polymer surface. Since the proteins are bonded to the substrate surface, they can stimulate cell adhesion and proliferation.     

Plasma-modified and polyethylene glycol-grafted polymers for potential tissue engineering applications

Modified and grafted polymers may serve as building blocks for creating artificial bioinspired nanostructured surfaces for tissue engineering. Polyethylene (PE) and polystyrene (PS) were modified by Ar plasma and the surface of the plasma activated polymers was grafted with polyethylene glycol (PEG). The changes in the surface wettability (contact angle) of the modified polymers were examined by goniometry. Atomic Force Microscopy (AFM) was used to determine the surface roughness and morphology and electrokinetical analysis (Zeta potential) characterized surface chemistry of the modified polymers. Plasma treatment and subsequent PEG grafting lead to dramatic changes in the polymer surface morphology, roughness and wettability. The plasma treated and PEG grafted polymers were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation were studied. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with PEG increases cell proliferation, especially on PS. The cell proliferation was shown to be an increasing function of PEG molecular weight.     

Average absorption coefficients and mean free paths of radiation of the continuous spectrum in the region of multiple and total ionization

Consideration is given to problems of averaging absorption coefficients of atoms and multiply charged ions with passage to the region of total ionization. It is shown that correct allowance for ionization of hydrogen-like ions makes it possible to pass automatically to coefficients of absorption in the continuous spectrum. A comparison is made with detailed calculations of mean free paths for a number of elements.     

Ion-Beam Deposition of Thin AlN Films on Al2O3 Substrate

Technical Physics Letters - Thin aluminum nitride (AlN) films on sapphire (Al2O3) substrates were grown by means of ion-beam deposition (IBD) and studied by methods of scanning electron microscopy,...     

Chemical processes in the earth’s atmosphere disturbed by volcanic ejection

The dynamics of formation of a stratospheric aerosol is traced on the basis of a one-dimensional photochemical model of a horizontally homogeneous atmosphere allowing for only vertical transfer of impurities. Calculations show that below 30 km sulfur is mainly in the form of CSO, whereas at higher altitudes it is in the form of sulfuric acid.     

Integration of direct carbon fuel cells with concentrated solar power

In this paper, we will report on a study on the thermodynamic feasibility of a concept that realizes the cracking of methane with a concentrated solar power (CSP) reactor and electricity production with a direct carbon fuel cell (DCFC) and its possible contribution to a clean energy supply for Europe in the long-term future. The natural gas (methane) is decomposed in an endothermic reaction into hydrogen and carbon. The separated carbon is fed to a direct carbon fuel cell (DCFC) and converted with high efficiency to electric power. A model of the proposed concept is carried out in the flow sheet program Cycle-Tempo and the results of the simulations and the corresponding analysis are presented in this paper. Finally the location factors influencing the implementation of this concept in the north of Africa are evaluated.     

Toward clinical proteomics on a next-generation sequencing platform

We report the first next generation sequencing (NGS) application to identify and quantify proteins. Customization of protein specific aptamers enabled direct conversion of serum protein information into NGS read outs. The intrinsic ability of aptamer sequencing to highly multiplex protein detection and quantification, together with the prospect of DNA sequencing further evolving into a commodity technology, could constitute the core of a novel, universal diagnostics paradigm.     

Electrical Properties of Beryllium-Doped Gd2Zr2O7

Inorganic Materials - Dense Gd2Zr2O7-based ceramics with the composition Gd2Zr1.9Be0.1O6.9, containing heterovalently substituted beryllium on the zirconium site, have been prepared for the first...     

Internal clock and memory processes in animal timing.

Two experiments, involving a total of 6 male pigeons, investigated temporal control of behavior within the framework of an internal clock model. Ss were exposed to signaled fixed interval (FI) 30-sec trials mixed with extended unreinforced (baseline) trials. On unreinforced break trials, the signal was interrupted for a period of time after trial onset. In Exp 1, comparisons between the peak time obtained on baseline and on break trials produced peak time shifts that were longer than those expected if the clock had stopped during the break but shorter than if the clock had reset. In Exp 2, systematic manipulations of duration and location of breaks produced peak time shifts that were nonlinear functions of break duration and that varied linearly with break location. The obtained peak times were more consistent with a continuous memory decay model than with the stop-retain or the reset hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)