26 research outputs found
How to pin down the CP quantum numbers of a Higgs boson in its tau decays at the LHC
We investigate how the CP quantum numbers of a neutral Higgs boson or
spin-zero resonance, produced at the CERN Large Hadron Collider, can be
determined in its tau-pair decay mode. We use a method developed in an earlier
paper based on the distributions of two angles and apply it to the major
1-prong tau decays. We show for the resulting dilepton, lepton-pion, and
two-pion final states that appropriate selection cuts significantly enhance the
discriminating power of these observables. From our analysis we conclude that,
provided a Higgs boson will be found at the LHC, it appears feasible to collect
the event numbers needed to discriminate between a CP-even and -odd Higgs boson
and/or between Higgs boson(s) with CP-conserving and CP-violating couplings
after several years of high-luminosity runs.Comment: 23 pages, 12 figures; Several sentences and references adde
Biofunctionalization of zinc oxide nanowires for DNA sensory applications
We report on the biofunctionalization of zinc oxide nanowires for the attachment of DNA target molecules on the nanowire surface. With the organosilane glycidyloxypropyltrimethoxysilane acting as a bifunctional linker, amino-modified capture molecule oligonucleotides have been immobilized on the nanowire surface. The dye-marked DNA molecules were detected via fluorescence microscopy, and our results reveal a successful attachment of DNA capture molecules onto the nanowire surface. The electrical field effect induced by the negatively charged attached DNA molecules should be able to control the electrical properties of the nanowires and gives way to a ZnO nanowire-based biosensing device
Nachtr\ue4ge zu Lepidoptera Niepeltiana
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DNA hybridization assay at individual, biofunctionalized zinc oxide nanowires
Reliable and efficient identification of DNA is a major goal in on-site diagnostics. One dimensional nanostructures like nanowires (NW) represent potential sensor structures due to their extreme surface-to-bulk ratio, enabling enhanced biomolecule binding which results in optimal signals. While silicon NW are already well studied, NW made from other materials with promising properties like ZnO are not yet established as NW sensor material for bioanalytics. Here we demonstrate the DNA functionalization of ZnO NW even at the single NW level and their successful application in a DNA hybridization assay. ((c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Effects of hydroxylation and silanization on the surface properties of ZnO nanowires
Silanization is commonly used to form bonds between inorganic materials and biomolecules as a step in the surface preparation of solid-state biosensors. This work investigates the effects of silanization with amino-propyldiethoxymethylsilane on hydroxylated sidewalls of zinc oxide (ZnO) nanowires (NWs). The surface properties and electrical characteristics of NWs are analyzed by different techniques after their hydroxylation and later silanization. Contact angle measurements reveal a stronger hydrophobic behavior after silanization, and X-ray photoelectron spectroscopy (XPS) results show a reduction of the surface dipole induced by the replacement of the hydroxyl group with the amine terminal group. The lower work function obtained after silanization in contact potential measurements corroborates the attenuation of the surface dipole observed in XPS. Furthermore, the surface band bending of NWs is determined from surface photovoltage measurements upon irradiation with UV light, yielding a 0.5 eV energy in hydroxylated NWs, and 0.18 eV, after silanization. From those results, a reduction in the surface state density of 3.1 Ă 1011 cmâ2 is estimated after silanization. The currentâvoltage (IâV) characteristics measured in a silanized single NW device show a reduction of the resistance, due to the enhancement of the conductive volume inside the NW, which also improves the linearity of the IâV characteristic