Effect of Cr additions on the electrical properties of Ni–BaTiO3 ultra-thin multilayer capacitors

Multilayer ceramic capacitors based on BaTiO₃ dielectric compositions and Ni inner electrodes have complex interfacial reactions that impact the continuity of the inner electrode microstructure. Previously we demonstrated that through the addition of Cr to Ni, a significant improvement in the continuity of ultra-thin Ni electrodes in Ni–BaTiO₃ multilayer capacitors could be achieved. Here, the effect of the Cr addition to the nickel electrode pastes is studied with regard to the electrical properties. Low-field electrical measurements demonstrate no major differences between Cr doped Ni and undoped Ni. However, high-field measurements show a significant decrease to the total capacitor resistance. Under a critical electrical bias the conductivity significantly increases due to a Fowler–Nordheim tunneling conduction though the interfacial Schottky barrier at the dielectric–electrode interface; the onset voltage of this conduction is much lower than with the undoped nickel. Based on these results, we evaluate criteria for the selection of an appropriate refractory metal in order to improve the Ni electrode continuity.     

Plant sources of vitamin A and human nutrition: red palm oil does the job

Studies in India demonstrate that the beta-carotene in red palm oil is as effective as high-dose retinyl palmitate as a supplement to restore and preserve vitamin A nutriture in schoolchildren and may be an effective food-based strategy to combat hypovitaminosis A.     

Dental pain and suffering prior to the advent of modern dentistry

In Prehistoric and Mediaeval times few dentitions in this country remained intact much after the age of 40-45 years. The point is made that dental caries and periodontal disease played little part in this early disintegration and it is unlikely that the population of this time suffered severely with their teeth. A change in dietary habits in the late seventeenth and early eighteenth century measurably increased the lifespan of the dentition, but also radically altered the prevalence of caries. This change is likely to have been responsible for a vast increase in dentally-related pain and suffering which was only capable of being tackled as a social problem by the advent of modern dentistry.     

Apoprotein structure in the LH2 complex from Rhodopseudomonas acidophila strain 10050: modular assembly and protein pigment interactions

The refined structure of the peripheral light-harvesting complex from Rhodopseudomonas acidophila strain 10050 reveals a membrane protein with protein-protein interactions in the trans-membrane region exclusively of a van der Waals nature. The dominant factors in the formation of the complex appear to be extramembranous hydrogen bonds (suggesting that each apoprotein must achieve a fold close to its final structure in order to oligomerize), protein-pigment and pigment-pigment interactions within the membrane-spanning region. The pigment molecules are known to play an important role in the formation of bacterial light-harvesters, and their extensive mediation of structural contacts within the membrane bears this out. Amino acid residues determining the secondary structure of the apoproteins influence the oligomeric state of the complex. The assembly of the pigment array is governed by the apoproteins of LH2. The particular environment of each of the pigment molecules is, however, influenced directly by few protein contacts. These contacts produce functional effects that are not attributable to a single cause, e.g. the arrangement of an overlapping cycle of chromophores not only provides energy delocalisation and storage properties, but also has consequences for oligomer size, pigment distortion modes and pigment chemical environment, all of which modify the precise function of the complex. The evaluation of site energies for the pigment array requires the consideration of a number of effects, including heterogeneous pigment distortions, charge distributions in the local environment and mechanical interactions.     

Fas (APO-1, CD95)-mediated apoptosis in thyroid cells is regulated by a labile protein inhibitor

To determine whether thyroid cell apoptosis observed in autoimmune thyroid disease could be related to activation of the Fas pathway, we examined the expression and function of Fas on thyroid follicular cells in vitro. Fas messenger RNA was found to be present using two different techniques and was expressed at equal levels in thyrocytes cultured either in the presence or absence of TSH. Fas antigen protein expression was demonstrated by Western blot of thyroid cell lysates and by immunohistochemical staining of thyrocytes, and the amount of Fas protein present did not appear to vary regardless of culture conditions. Despite expressing substantial amounts of Fas protein, thyrocytes treated with anti-Fas monoclonal antibody failed to undergo apoptosis. The addition of either interferon-gamma or interleukin-1beta to the anti-Fas-treated cell cultures also did not promote apoptotic signaling through this pathway. In contrast, the concomitant administration of cycloheximide allowed the induction of apoptosis through the activation of Fas in thyrocytes. These results suggest that Fas is constitutively expressed in thyrocytes, but that the induction of apoptosis through the Fas pathway is blocked by a labile protein inhibitor.