Solid-state high-resolution 29Si NMR spectroscopy of synthetic 14 Å, 11 Å and 9 Å tobermorites

A new method for the investigation of the structure of silicates - solid-state high-resolution ²⁹Si NMR spectroscopy - was used for the investigation of 14 Å, 11 Å and 9 Å tobermorites prepared under different conditions. It is possible to determine selectively the individual SiO₄ structural units in tobermorites (end groups, chain middle groups, branching sites, etc.) and to draw conclusions about the type and structure of the silicate anions in the lattice. Synthetic 14 Å tobermorite consists predominantly of single chains, the 11 Å and 9 Å tobermorites contain, depending on the method of preparation, double chains and/or single chains.     

Assessment of regional myocardial uptake and metabolism of omega-(p-123I-phenyl) pentadecanoic acid with serial single-photon emission tomography

The utility of myocardial imaging and assessment of regional myocardial metabolism of omega-(123I-paraphenyl-)pentadecanoic acid (I-PPA) by means of serial single-photon tomography is demonstrated in animal experiments. High quality cross sectional images of dog hearts with clear delineation of left ventricular walls are obtained. Myocardial infarcts are visualized as areas of deficient radioactivity uptake. I-PPA elimination from non-infarcted myocardial regions is significantly (p less than 0.001) prolonged when compared with unaffected controls. Hence, not only localized absence of uptake of free fatty acid by infarcted myocardium can be demonstrated with serial single-photon tomography but also general impairment of cardiac FFA-metabolism.     

Analysis of protein adsorption and binding at biosensor polymer interfaces using X-ray photon spectroscopy and scanning electrochemical microscopy

We describe a method, based on X-ray photoelectron spectroscopy (XPS) measurements, to assess the extent of protein adsorption or binding on a variety of different muTAS and biosensor interfaces. Underpinning this method is the labeling of protein molecules with either iodine- or bromine-containing motifs by using protocols previously developed for radiotracer studies. Using this method, we have examined the adsorption and binding properties of a variety of modified electrodeposited polymer interfaces as well as other materials used in muTAS device fabrication. Using polymer interfaces modified with poly(propylene glycol) (PPG) chains, our results indicate that a chain of at least approximately 30 monomer units is required to inhibit nonspecific adsorption from concentrated protein solutions. The XPS methodology was also used to probe specific binding of avidins and enzyme conjugates thereof to biotinylated and mixed biotin/PPG-modified polymer interfaces. In one example, using competitive binding, it was established that the mode of binding of a peroxidase-streptavidin conjugate to a biotinylated modified polymer interface was primarily via the streptavidin moiety (as opposed to nonspecific binding via the enzyme conjugate). XPS evaluation of nonspecific and specific peroxidase-streptavidin immobilization on various functionalized polymers has guided the design and fabrication of functionalized interdigitated electrodes in a biosensing muTAS device. Subsequent characterization of this device using scanning electrochemical microscopy (SECM) corroborated the adsorption and binding previously inferred from XPS measurements on macroscale electrodes.     

Is there theoretical evidence for a metallic carbon polymorph with space group symmetry at ambient conditions?

Quantum mechanical calculations based on density functional theory and the generalised gradient approximation show that the equilibrium lattice parameter of a carbon polymorph with space group symmetry would be 3.08 Å, and hence very different from that of diamond. No local minimum in the dependence of the total energy on the lattice parameter has been found. Such a polymorph would be approximately 5 eV atom⁻¹ less stable than diamond, suggesting that its synthesis is very unlikely. This finding is consistent with older density functional calculations and contradicts recent results of LCAO calculations, which have been used to support the interpretation of experimental data as showing the existence of a metallic carbon polymorph with space group symmetry .     

Psychological assessment of candidates for solid organ transplantation.

The role of psychologists, who can assist in preparing clients for transplant surgery and support them postsurgery to sustain the complex maintenance protocol, is outlined. An overview of specific procedures used in the psychological evaluation and treatment of solid organ transplant patients, a discussion of general issues involved in treating these patients, and case vignettes are provided. As transplants become more common, the need for additional psychologists as part of multidisciplinary treatment teams increases. Because many patients live great distances from the transplant center, community psychologists may be enlisted to treat organ transplant patients and to collaborate with psychologists on transplant teams. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calibration of an Absolute Radiation Thermometer for Accurate Determination of Fixed-Point Temperatures

For accurate determinations of thermodynamic temperature, NPL has developed its absolute radiation thermometer (ART), which is calibrated traceably against a cryogenic radiometer. This article reviews some of the potential sources of systematic uncertainty present in the calibration and use of ART. In particular, this article is concerned with the evaluation of the size-of-source effect and the lens transmittance, as well as potential differences in the responsivity of a transfer trap detector when calibrated in terms of radiant power and used in irradiance mode.     

Charge accumulation in the dielectric of the nanocluster NVM MOS structures under anti- and unipolar W/E window formation

This paper focuses on the detailed study of the unipolar recharging phenomenon of the nanocluster NVM cells based upon the electron emission from the nanodots and their subsequent neutralization. It is shown that electron emission from nanodots is a very fast and effective process with a time constant <5 ms, but the subsequent neutralization of the positive accumulated charge is strongly dependent on the excess of Si atoms stored in the nanodots.