The lattice site occupation of 3d-type impurities in Cr
3Si doped with Fe, Co and Ni were studied using the Extended X-ray Absorption Fine Structure (EXAFS) technique, X-rays and magnetic ...susceptibility measurements. The EXAFS measurements were performed particularly carefully on the K-edge of chromium and cobalt. EXAFS data strengthened by simulations of the spectra show unambiguously that the impurities are occupying mostly Cr-sites. The magnetic state of the alloys has been studied theoretically using the Wien2k code. It is observed that if calculations are not carried out on an appropriately fine mesh of points in
k-space, one can get the result indicating ferromagnetism although the overall magnetic moment per formula unit is weak.
Viral infections induce extensive T cell proliferation in vivo. However, only a small fraction (1-5%) of the activated T cells have been shown to be virus specific leading to the prevailing notion ...that most of the T cell expansion represents cytokine-mediated by-stander activation and/or cross reactive stimulation of non specific cells. To re-examine this issue we quantitated antigen specific CD8 T cells during acute LCMV infection of mice using three sensitive techniques: (i) intracellular cytokine production, (ii) single cell ELISPOT and (iii) direct visualization of antigen specific CD8 T cells by staining with MHC class I tetramers + peptide. In contrast to previous estimates, we found that 50-70% of the activated CD8 T cells were LCMV specific. This represented > or = 10,000-fold increase (approximately 2 x 10(7) virus specific cells/spleen) in 8 days with the peak expansion occurring between day 3 and 5 during which period virus specific CD8 T cells had an estimated division time of approximately 8 hours. Following viral clearance, the number of antigen specific CD8 T cells dropped to 1 x 10(6) per spleen and were maintained at this level for the life of the mouse. Upon rechallenge with LCMV, memory CD8 T cells rapidly proliferated and again comprised > 50% of the total CD8 T cells. In contrast, upon challenge with a heterologous virus such as vaccinia, there was no change in the number of LCMV specific memory CTL, despite a substantial increase in the number of activated CD8 T cells. Taken together, these results show that much of the CD8 T cell expansion seen during viral infection represents antigen specific cells.
The decades surrounding the turn of the millennium will be remembered as a time of extraordinary opportunity in cancer communication. In 1990, the number of age-adjusted deaths due to cancer in the ...U.S. population began a slow steady decline after a century of disparaging increase. Reasons for this decline have been attributed to long-awaited successes in primary prevention, especially related to tobacco, and early detection for cervical, breast, prostate, and colorectal cancers, as well as advances in treatment. This was also a time of unparalleled change in the cancer communication environment. Scientific health discoveries escalated with the completion of the Human Genome project in 2003, and penetration of the Internet made health information available directly to consumers. To seize the opportunity afforded by these changes, the National Cancer Institute (NCI) launched the Health Information National Trends Survey (HINTS). Fielded for the first time in 2003, the HINTS is a nationally representative, general population survey of noninstitutionalized adults in the United States 18 years and older. This supplement contains a compilation of original research conducted using the data generated by the first administration of the HINTS telephone interviews. Covering topics in cancer knowledge, cancer cognition, risk perception, and information seeking, the articles represent an interdisciplinary view of cancer communication at the turn of the millennium and offer insight into the road ahead.
Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of
x and
Q
2 using the ZEUS detector. The evolution of the scaled momentum,
x
p
, with
Q
2, ...in the range 10 to 1280 GeV
2, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of
Q
2.
Influence of chromium incorporation on structural and optical properties of titanium dioxide nanopowders obtained by flame spray synthesis, FSS is studied by means of: X-ray diffraction, XRD; Raman ...spectroscopy; transmission electron spectroscopy, TEM; photoelectron spectroscopy, XPS and optical spectrophotometry over the ultraviolet, UV and visible range of the light spectrum from 250
nm to 2200
nm. The specific surface area, SSA, of the powders has been adjusted from 48
m
2/g for TiO
2
+
0.1at.% Cr to 177
m
2/g for TiO
2
+
15 at.% Cr which is accompanied by a decrease in the anatase grain size from 21
nm to 5
nm. The anatase-to-rutile ratio changes with Cr
3+ concentration but there is no evidence of precipitation of chromium oxides or chromium titanates. Incorporation of Cr
3+ into TiO
2 lattice, as proved by XPS, is found to affect the electronic structure of TiO
2, as indicated by the optical spectrophotometry. The impurity band is formed within the forbidden band gap of titanium dioxide which results in the additional absorption within the visible range of the light spectrum. The general aim of this work is to improve the visible light absorption and hence the efficiency of photocatalytic decomposition of organic contaminants.
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