4,376 research outputs found
Extended x-ray absorption fine structure study of porous GaSb formed by ion implantation
Porous GaSb has been formed by Ga ion implantation into crystalline GaSb substrates at either room temperature or â180 °C. The morphology has been characterized using scanning electron microscopy and the atomic structure was determined using extended x-ray absorption fine structure spectroscopy. Room-temperature implantation at low fluences leads to the formation of âŒ20-nm voids though the material remains crystalline. Higher fluences cause the microstructure to evolve into a network of amorphous GaSb rods âŒ15 nm in diameter. In contrast, implantation at â180 °C generates large, elongated voids but no rods. Upon exposure to air, the surface of the porous material is readily oxidized yielding GaâOâ and metallic Sb precipitates, the latter resulting from the reduction of unstable SbâOâ. We consider and discuss the atomic-scale mechanisms potentially operative during the concurrent crystalline-to-amorphous and continuous-to-porous transformations
The in silico macrophage: toward a better understanding of inflammatory disease
Macrophages function as sentinel, cell-regulatory hubs capable of initiating,
perpetuating and contributing to the resolution of an inflammatory response,
following their activation from a resting state. Highly complex and varied gene
expression programs within the macrophage enable such functional diversity. To
investigate how programs of gene expression relate to the phenotypic attributes
of the macrophage, the development of in silico modeling methods is needed.
Such models need to cover multiple scales, from molecular pathways in
cell-autonomous immunity and intercellular communication pathways in tissue
inflammation to whole organism response pathways in systemic disease. Here, we
highlight the potential of in silico macrophage modeling as an amenable and
important yet under-exploited tool in aiding in our understanding of the immune
inflammatory response. We also discuss how in silico macrophage modeling can
help in future therapeutic strategies for modulating both the acute protective
effects of inflammation (such as host defense and tissue repair) and the
harmful chronic effects (such as autoimmune diseases).Comment: 7 pages plus 1 figur
TWEAK: a novel biomarker for lupus nephritis?
Renal involvement is common in systemic lupus erythematosus. Early diagnosis of lupus nephritis (LN), allowing the instigation of appropriate therapy, remains an important clinical challenge. Current biomarkers in clinical practice are less than ideal, lacking both sensitivity and specificity. In the previous issue of Arthritis Research & Therapy, Schwartz and colleagues demonstrated the potential value of urinary TNF-like weak inducer of apoptosis (uTWEAK) as a biomarker for LN. They showed that uTWEAK is elevated in subjects with LN at diagnosis compared with those with systemic lupus erythematosus but no renal disease, and correlates with the degree of clinical disease activity. These data are thought-provoking and provide the platform for future longer-term studies
Study of moments of event shapes in e+e- annihilation using JADE data
Data from e+e- annihilation into hadrons collected by the JADE experiment at
centre-of-mass energies between 14 GeV and 44 GeV were used to study moments of
event shape distributions. The data were compared with Monte Carlo models and
with predictions from QCD NLO order calculations. The strong coupling constant
measured from the moments is alpha_S(M_Z) = 0.1286 +/- 0.0007 (stat) +/- 0.0011
(expt) +/- 0.0022 (had) +/- 0.0068 (theo), alpha_S(M_Z) = 0.1286 +/- 0.0072
(total error), consistent with the world average. However, systematic
deficiencies in the QCD NLO order predictions are visible for some of the
higher moments.Comment: JADE note 147 submitted as contributed paper to ICHEP 2004, corrected
statistical error of 6 observable average and several typo
Untersuchungen zum Gehalt an ME und praecaecal verdaulichen AminosÀuren aus einem Gemisch thermisch behandelter Körnerleguminosen (LEGUMI-thermŸ) beim Broiler
The objective of this study was to assess the effect of heating a mixture of grain legumes based on sweet lupins, faba beans, and peas (1:1:1, toasted âLEGUMItherm Âźâ; untreated: âLEGUMI-mixâ) on the content of metabolisable energy (ME) and precaecal digestible (pc) amino acids for broilers. The mean of amino acid digestibility of LEGUMI-mix and LEGUMI-therm was 88 and 87 %. The ME content of the mixture ranged between 11.9 (LEGUMI-therm) and 12.1 MJ/kg DM (LEGUMI-mix). Both parameters were unaffected by heating
Measurement of the Strong Coupling Constant alpha_S from the Four-Jet Rate in e+e- Annihilation using JADE data
Data from e+e- annihilation into hadrons collected by the JADE experiment at
centre-of-mass energies between 14 GeV and 44 GeV were used to study the
four-jet rate as a function of the Durham algorithm's resolution parameter
y_cut. The four-jet rate was compared to a QCD NLO order calculations including
NLLA resummation of large logarithms. The strong coupling constant measured
from the four-jet rate is alpha_S(M_Z) = 0.1169 +/- 0.0004 (stat) +/- 0.0012
(expt) +/- 0.0021 (had) +/- 0.0007 (theo), alpha_S(M_Z) = 0.1169 +/- 0.0026
(total error) in agreement with the world average.Comment: JADE note 146 submitted as contributed paper to ICHEP 200
Nanoscale density fluctuations in swift heavy ion irradiated amorphous SiO2
We report on the observation of nanoscale density fluctuations in 2 ÎŒm thick amorphous SiOâ layers irradiated with 185 MeV Au ions. At high fluences, in excess of approximately 5âĂâ10ÂčÂČ ions/cmÂČ, where the surface is completely covered by ion tracks, synchrotron small angle x-ray scattering measurements reveal the existence of a steady state of density fluctuations. In agreement with molecular dynamics simulations, this steady state is consistent with an ion track âannihilationâ process, where high-density regions generated in the periphery of new tracks fill in low-density regions located at the center of existing tracks.The authors acknowledge the Australian Research
Council and the Australian Synchrotron Research Program
for financial support and thank the staff at the ANU Heavy
Ion facility for their continued technical assistance. O.P.,
F.D., and K.N. acknowledge financial support from the
Academy of Finland under its Centre of Excellence program
as well as the OPNA project, and grants of computer
capacity from CSC
Formation and structural characterization of Ni nanoparticles embedded in SiOâ
Face-centered cubic Ni nanoparticles were formed in SiOâ by ion implantation and thermal annealing. Small-angle x-ray scattering in conjunction with transmission electron microscopy was used to determine the nanoparticle size as a function of annealing temperature, whereas the local atomic structure was measured with x-ray absorption spectroscopy. The influence of finite-size effects on the nanoparticle structural properties was readily apparent and included a decrease in coordination number and bond length and an increase in structural disorder for decreasing nanoparticle size. Such results are consistent with the non-negligible surface-to-volume ratio characteristic of nanoparticles. In addition, temperature-dependent x-ray absorption spectroscopy measurements showed the mean vibrational frequency (as obtained from the Einstein temperature) decreased with decreasing nanoparticle size. This reduction was attributed to the greater influence of the loosely bound, under-coordinated surface atoms prevailing over the effects of capillary pressure, the former enhancing the low frequency modes of the vibrational density of statesThis work was financially supported by the Australian
Synchrotron and the Australian Research Council with access to equipment provided by the Australian Nanofabrication
Facility
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