157 research outputs found
Modelling the Deformation Behaviour of W/Cu Composites by a Self-Consistent Matricity Model
 
The prototypical organic-oxide interface: intra-molecular resolution of sexiphenyl on InO(111)
The performance of an organic-semiconductor device is critically determined
by the geometric alignment, orientation, and ordering of the organic molecules.
While an organic multilayer eventually adopts the crystal structure of the
organic material, the alignment and configuration at the interface with the
substrate/electrode material is essential for charge injection into the organic
layer. This work focuses on the prototypical organic semiconductor
para-sexiphenyl (6P) adsorbed on InO(111), the thermodynamically most
stable surface of the material that the most common transparent conducting
oxide, indium tin oxide (ITO) is based on. The onset of nucleation and
formation of the first monolayer are followed with atomically-resolved scanning
tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM).
Annealing to 200C provides sufficient thermal energy for the molecules
to orient themselves along the high-symmetry directions of the surface, leading
to a single adsorption site. The AFM data suggests a twisted adsorption
geometry. With increasing coverage, the 6P molecules first form a loose network
with poor long-range order. Eventually the molecules re-orient and form an
ordered monolayer. This first monolayer has a densely packed, well-ordered
(21) structure with one 6P per InO(111) substrate unit cell,
i.e., a molecular density of 5.6410 cm
Regularization of statistical inverse problems and the Bakushinskii veto
In the deterministic context Bakushinskii's theorem excludes the existence of
purely data driven convergent regularization for ill-posed problems. We will
prove in the present work that in the statistical setting we can either
construct a counter example or develop an equivalent formulation depending on
the considered class of probability distributions. Hence, Bakushinskii's
theorem does not generalize to the statistical context, although this has often
been assumed in the past. To arrive at this conclusion, we will deduce from the
classic theory new concepts for a general study of statistical inverse problems
and perform a systematic clarification of the key ideas of statistical
regularization.Comment: 20 page
Low-Cost Methods for Molecular Characterization of Mutant Plants: Tissue Desiccation, DNA Extraction and Mutation Discovery: Protocols
Plant Breeding/Biotechnology; Biological Techniques; Nucleic Acid Chemistr
Low-Cost Methods for Molecular Characterization of Mutant Plants: Tissue Desiccation, DNA Extraction and Mutation Discovery: Protocols
Plant Breeding/Biotechnology; Biological Techniques; Nucleic Acid Chemistr
Fragmentation of pooled PCR products for highly multiplexed TILLING
Improvements to massively parallel sequencing have allowed the routine recovery of natural
and induced sequence variants. A broad range of biological disciplines have benefited from this, ranging
from plant breeding to cancer research. The need for high sequence coverage to accurately recover single
nucleotide variants and small insertions and deletions limits the applicability of whole genome approaches.
This is especially true in organisms with a large genome size or for applications requiring the screening of
thousands of individuals, such as the reverse-genetic technique known as TILLING. Using PCR to target and
sequence chosen genomic regions provides an attractive alternative as the vast reduction in interrogated
bases means that sample size can be dramatically increased through amplicon multiplexing and multidimensional
sample pooling while maintaining suitable coverage for recovery of small mutations. Direct
sequencing of PCR products is limited, however, due to limitations in read lengths of many next generation
sequencers. In the present study we show the optimization and use of ultrasonication for the simultaneous
fragmentation of multiplexed PCR amplicons for TILLING highly pooled samples. Sequencing performance
was evaluated in a total of 32 pooled PCR products produced from 4096 chemically mutagenized Hordeum
vulgare DNAs pooled in three dimensions. Evaluation of read coverage and base quality across amplicons
suggests this approach is suitable for high-throughput TILLING and other applications employing highly
pooled complex sampling schemes. Induced mutations previously identified in a traditional TILLING screen
were recovered in this dataset further supporting the efficacy of the approach
Measurement of neutron capture on Ca at thermal and thermonuclear energies
At the Karlsruhe pulsed 3.75\,MV Van de Graaff accelerator the thermonuclear
Ca(n,)Ca(8.72\,min) cross section was measured by the
fast cyclic activation technique via the 3084.5\,keV -ray line of the
Ca-decay. Samples of CaCO enriched in Ca by 77.87\,\% were
irradiated between two gold foils which served as capture standards. The
capture cross-section was measured at the neutron energies 25, 151, 176, and
218\,keV, respectively. Additionally, the thermal capture cross-section was
measured at the reactor BR1 in Mol, Belgium, via the prompt and decay
-ray lines using the same target material. The
Ca(n,)Ca cross-section in the thermonuclear and thermal
energy range has been calculated using the direct-capture model combined with
folding potentials. The potential strengths are adjusted to the scattering
length and the binding energies of the final states in Ca. The small
coherent elastic cross section of Ca+n is explained through the nuclear
Ramsauer effect. Spectroscopic factors of Ca have been extracted from
the thermal capture cross-section with better accuracy than from a recent (d,p)
experiment. Within the uncertainties both results are in agreement. The
non-resonant thermal and thermonuclear experimental data for this reaction can
be reproduced using the direct-capture model. A possible interference with a
resonant contribution is discussed. The neutron spectroscopic factors of
Ca determined from shell-model calculations are compared with the values
extracted from the experimental cross sections for Ca(d,p)Ca and
Ca(n,)Ca.Comment: 15 pages (uses Revtex), 7 postscript figures (uses psfig), accepted
for publication in PRC, uuencoded tex-files and postscript-files also
available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Ca.u
Reaction rates for Neutron Capture Reactions to C-, N- and O-isotopes to the neutron rich side of stability
The reaction rates of neutron capture reactions on light nuclei are important
for reliably simulating nucleosynthesis in a variety of stellar scenarios.
Neutron capture reaction rates on neutron-rich C-, N-, and O-isotopes are
calculated in the framework of a hybrid compound and direct capture model. The
results are tabulated and compared with the results of previous calculations as
well as with experimental results.Comment: 33 pages (uses revtex) and 9 postscript figures, accepted for
publication in Phys. Rev.
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