Aging effects of anatase TiO2 nanoparticles in Li-ion batteries.

Anatase TiO2 nanoparticles with a diameter of 5 nm have been investigated as a negative intercalation electrode material for Li-ion batteries. The focus was on the stability upon cycling within four different potential ranges, namely from 1.5, 1.2, 1.0 and 0.7 V vs. Li/Li(+) as the lower potential limit to 3.0 V vs. Li/Li(+) as the upper potential limit. While a lower cut-off potential allows for a higher amount of charge stored, the irreversible processes induce a faster fading of the specific charge. Galvanostatic cycling (GC), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) experiments suggest that SEI formation has a negligible contribution to the irreversible processes. It appears more plausible that an irreversible degradation of the bulk phase occurs, leading to a decrease in the amount of active sites. Moreover, it has been observed that this degradation appears as an anodic shift of the thermodynamic potential of (de-)intercalation of Li-ions in the TiO2 structure. The shift is caused by a change in the activity of Li-ions in the solid phase, which is driven by changes in the ionic atmosphere of the crystal.

Confocal Raman microscopy of liquid-crystal-filled polymer capsules made by photo-enforced stratification.

The applicability of confocal Raman microscopy for characterizing thin liquid-crystal (LC) filled polymer capsules obtained by photo-enforced stratification is demonstrated. The investigated structure consists of an array of polymer capsules (typical size 500 x 500 x 20 microm) filled with LC material and is made by photopolymerization of a mixture of monomers and LC. Such an array can be used as the electro-optical component in liquid crystal displays. Confocal Raman microscopy does not require complex sample preparation, is non-invasive, and is shown to have adequate spatial and depth resolution. Although Raman spectroscopy is inherently insensitive, the use of data preprocessing and computational modeling makes it possible to quantify both the conversion of monomer to polymer and the compositions of both the polymer-rich and the LC-rich phase.

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7.

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the potential for large-scale outbreaks from contaminated food supplies have propelled intensive research on the pathogenesis and detection of E. coli O157:H7 (ref. 4). Here we have sequenced the genome of E. coli O157:H7 to identify candidate genes responsible for pathogenesis, to develop better methods of strain detection and to advance our understanding of the evolution of E. coli, through comparison with the genome of the non-pathogenic laboratory strain E. coli K-12 (ref. 5). We find that lateral gene transfer is far more extensive than previously anticipated. In fact, 1,387 new genes encoded in strain-specific clusters of diverse sizes were found in O157:H7. These include candidate virulence factors, alternative metabolic capacities, several prophages and other new functions--all of which could be targets for surveillance.

Expression of tissue-type transglutaminase correlates positively with metastatic properties of human melanoma cell lines.

In this study the relationship between tissue-type transglutaminase (TGase2) activity and the propensity to metastasize was investigated in human melanoma cell lines with different metastatic behavior. TGase2 catalyzes an acyl-transfer reaction between peptide-bound glutamine residues and primary amines, including the epsilon-amino group of lysine residues. Northern-blot analysis demonstrated that TGase2 RNA-expression (3.7 kb) was elevated in highly metastatic cell lines (MV3 and BLM) as compared to weakly metastatic ones (IF6 and 530). Immunoprecipitation and enzyme assays of TGase2 showed that the differential expression at the mRNA level was also reflected at the protein level. These findings reveal a positive relation between the expression of TGase2 and the metastatic properties of the human melanoma cell lines.

Monoclonal antibodies to cytoplasmic domains of the acetylcholine receptor.

Fourteen clonal hybridoma lines that secrete monoclonal antibodies (mabs) to the Torpedo acetylcholine receptor (AChR) have been isolated. When analyzed by an immunoreplica technique, two mabs recognized the alpha subunit, three reacted with the beta subunit, one reacted with the gamma chain, and five recognized the delta subunit. One mab failed to react with any of the subunits using this assay and two mabs recognized determinants found on both the gamma and the delta subunits. These were classified according to their reactivities with the membrane-bound Torpedo AChR. One category is comprised of mabs (including both anti-alpha mabs) that recognize extracellular epitopes. A second classification included mabs that are unable to bind the membrane-associated AChR. The third category is comprised of mabs directed against cytoplasmic epitopes of the AChR. The latter mabs, all of which recognize the gamma or delta subunits or both, bind only slightly to sealed, outside-out Torpedo vesicles. The binding is increased 10-20-fold by either alkaline extraction or treatment of the vesicles with 10 mM lithium diiodosalicylate but not by permeabilization of the vesicles with saponin. Three of the six mabs in this category react with frog muscle endplates but only if the cytoplasmic surface of the membrane is accessible.