2,901 research outputs found
Biologische producten natuurlijk verpakt
Hoe milieuvriendelijk zijn hernieuwbare en biologisch afbreekbare kunststofverpakkingen eigenlijk? Voor het verpakkend bedrijfsleven is het lastig om daarachter te komen en dus weloverwogen keuzes te maken. In het onderzoek ‘Natuurlijk verpakt’ – uitgevoerd door Wageningen UR Food & Biobased Research – is zoveel mogelijk informatie verzameld en samengevat
Microscopic thickness determination of thin graphite films formed on SiC from quantized oscillation in reflectivity of low-energy electrons
Low-energy electron microscopy (LEEM) was used to measure the reflectivity of
low-energy electrons from graphitized SiC(0001). The reflectivity shows
distinct quantized oscillations as a function of the electron energy and
graphite thickness. Conduction bands in thin graphite films form discrete
energy levels whose wave vectors are normal to the surface. Resonance of the
incident electrons with these quantized conduction band states enhances
electrons to transmit through the film into the SiC substrate, resulting in
dips in the reflectivity. The dip positions are well explained using
tight-binding and first-principles calculations. The graphite thickness
distribution can be determined microscopically from LEEM reflectivity
measurements.Comment: 7 pages, 3 figure
Reactive-site mutants of N-TIMP-3 that selectively inhibit ADAMTS-4 and ADAMTS-5: biological and structural implications.
Published versio
Resistively detected nuclear magnetic resonance via a single InSb two-dimensional electron gas at high temperature
We report on the demonstration of the resistively detected nuclear magnetic
resonance (RDNMR) of a single InSb two-dimensional electron gas (2DEG) at
elevated temperatures up to 4 K. The RDNMR signal of 115In in the simplest
pseudospin quantum Hall ferromagnet triggered by a large direct current shows a
peak-dip line shape, where the nuclear relaxation time T1 at the peak and the
dip is different but almost temperature independent. The large Zeeman,
cyclotron, and exchange energy scales of the InSb 2DEG contribute to the
persistence of the RDNMR signal at high temperatures.Comment: 11pages,3figure
Spectral properties of the X-ray binary pulsar LMC X-4 during different intensity states
We present spectral variations of the binary X-ray pulsar LMC X-4 observed
with the RXTE/PCA during different phases of its 30.5 day long third period.
Only out of eclipse data were used for this study. The 3-25 keV spectrum,
modeled with high energy cut-off power-law and iron line emission is found to
show strong dependence on the intensity state. Correlations between the Fe line
emission flux and different parameters of the continuum are presented here.Comment: 4 pages, 4 figure
Chemokine-induced secretion of gelatinase B in primary human monocytes
Chemokines help control normal leukocyte trafficking as well as their infiltration into tissues during acute and chronic inflammation. Matrix metalloproteinases (MMPs) help support the extravasation and infiltration of leukocytes through limited proteolysis of basement membranes and matrix material. The effect of the chemokines RANTES/CCL5, MCP-1/CCL and SDF-1 /CXCL12 on secretion of the matrix metalloproteinase B and its endogenous inhibitor TIMP-1 was studied. RANTES/CCL5 and SDF-1/CXCL12 were found to induce MMP-9 secretion in primary human monocytes while TIMP-1 secretion was not affected. RANTES/CCL5 effects were mediated through CCR1 because the CCR1 antagonist BX471 was found to effectively block RANTES/CCL5-induced MMP-9 secretion
Neutron Star Masses and Radii as Inferred from kilo-Hertz QPOs
Kilo-Hertz (kHz) Quasi-periodic oscillations (QPOs) have been discovered in
the X-ray fluxes of 8 low-mass X-ray binaries (LMXBs) with the Rossi X-ray
Timing Explorer (RXTE). The characteristics of these QPOs are remarkably
similar from one source to another. In particular, the highest observed QPO
frequencies for 6 of the 8 sources fall in a very narrow range: 1,066 to 1,171
Hz. This is the more remarkable when one considers that these sources are
thought to have very different luminosities and magnetic fields, and produce
very different count rates in the RXTE detectors. Therefore it is highly
unlikely that this near constancy of the highest observed frequencies is due to
some unknown selection effect or instrumental bias. In this letter we propose
that the highest observed QPO frequency can be taken as the orbital frequency
of the marginally stable orbit. This leads to the conclusions that the neutron
stars in these LMXBs are inside their marginally stable orbits and have masses
in the vicinity of 2.0 solar masses. This mass is consistent with the
hypothesis that these neutron stars were born with about 1.4 solar masses and
have been accreting matter at a fraction of the Eddington limit for 100 million
years.Comment: 7 pages, uses aas2pp4.sty, Accepted by ApJ
A search for cyclotron resonance features with INTEGRAL
We present an INTEGRAL observation of the Cen-Crux region in order to search
the electron cyclotron resonance scattering features from the X-ray binary
pulsars. During the AO1 200ks observation, we clearly detected 4 bright X-ray
binaries, 1 Seyfert Galaxy, and 4 new sources in the field of view. Especially
from GX301-2, the cyclotron resonance feature is detected at about 37 keV, and
width of 3--4 keV. In addition, the depth of the resonance feature strongly
depends on the X-ray luminosity. This is the first detection of luminosity
dependence of the resonance depth. The cyclotron resonance feature is
marginally detected from 1E1145.1-6141. Cen X-3 was very dim during the
observation and poor statistics disable us to detect the resonance
features.These are first INTEGRAL results of searching for the cyclotron
resonance feature.Comment: 4pages, 8figures, To be published in the Proceedings of the 5th
INTEGRAL Workshop: "The INTEGRAL Universe", February 16-20, 2004, Munic
Resistively-detected NMR lineshapes in a quasi-one dimensional electron system
We observe variation in the resistively-detected nuclear magnetic resonance
(RDNMR) lineshapes in quantum Hall breakdown. The breakdown is locally occurred
in a gate-defined quantum point contact (QPC) region. Of particular interest is
the observation of a dispersive lineshape occured when the bulk 2D electron gas
(2DEG) is set to and the QPC filling factor to the vicinity
of , strikingly resemble the dispersive lineshape observed
on a 2D quantum Hall state. This previously unobserved lineshape in a QPC
points to simultaneous occurrence of two hyperfine-mediated spin flip-flop
processes within the QPC. Those events give rise to two different sets of
nuclei polarized in the opposite direction and positioned at a separate region
with different degree of electronic polarizations.Comment: Accepted as a rapid communication in PR
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