23,768 research outputs found
Method for the production of strongly adhesive films on titanium and titanium alloys with a metallization process
A process for the spray-application of a strongly adhesive, thick antifriction layer on titanium and titanium alloys is proposed. The titanium/titanium alloy component to be coated is first subjected to cleaning in a pickling bath with reducing additives and sand-blasting, then coated with an intermediate layer of nickel, after which the final layer is applied. The formation of TiNi at the interface ensures strong bonding of the antifriction layer
Determination of Strong-Interaction Widths and Shifts of Pionic X-Rays with a Crystal Spectrometer
Pionic 3d-2p atomic transitions in F, Na, and Mg have been studied using a bent crystal spectrometer. The pionic atoms were formed in the production target placed in the external proton beam of the Space Radiation Effects Laboratory synchrocyclotron. The observed energies and widths of the transitions are E=41679(3) eV and Γ=21(8) eV, E=62434(18) eV and Γ=22(80) eV, E=74389(9) eV and Γ=67(35) eV, in F, Na, and Mg, respectively. The results are compared with calculations based on a pion-nucleus optical potential
EDGE: a code to calculate diffusion of cosmic-ray electrons and their gamma-ray emission
The positron excess measured by PAMELA and AMS can only be explained if there
is one or several sources injecting them. Moreover, at the highest energies, it
requires the presence of nearby (hundreds of parsecs) and middle age
(maximum of hundreds of kyr) source. Pulsars, as factories of electrons
and positrons, are one of the proposed candidates to explain the origin of this
excess. To calculate the contribution of these sources to the electron and
positron flux at the Earth, we developed EDGE (Electron Diffusion and Gamma
rays to the Earth), a code to treat diffusion of electrons and compute their
diffusion from a central source with a flexible injection spectrum. We can
derive the source's gamma-ray spectrum, spatial extension, the all-electron
density in space and the electron and positron flux reaching the Earth. We
present in this contribution the fundamentals of the code and study how
different parameters affect the gamma-ray spectrum of a source and the electron
flux measured at the Earth.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017),
Bexco, Busan, Kore
Permeability measurements of two low-density phenolic-nylon chars Final report
Permeability measurements of low-density phenolic-nylon chars in gaseous nitrogen and heliu
A water-soluble tetraazaperopyrene dye as strong G-quadruplex DNA binder
The interactions of the water-soluble tetraazaperopyrene dye 1 with ct-DNA, duplex-[(dAdT)12⋅(dAdT)12], duplex-[(dGdC)12⋅(dGdC)12] as well as with two G-quadruplex-forming sequences, namely the human telomeric 22AG and the promotor sequence c-myc, were investigated by means of UV/visible and fluorescence spectroscopy, isothermal titration calorimetry (ITC) and molecular docking studies. Dye 1 exhibits a high affinity for G-quadruplex structures over duplex DNA structures. Furthermore, the ligand shows promising G-quadruplex discrimination, with an affinity towards c-myc of 2×107 m−1 (i.e., Kd=50 nm), which is higher than for 22AG (4×106 m−1). The ITC data reveal that compound 1 interacts with c-myc in a stoichiometric ratio of 1:1 but also indicate the presence of two identical lower affinity secondary binding sites per quadruplex. In 22AG, there are two high affinity binding sites per quadruplex, that is, one on each side, with a further four weaker binding sites. For both quadruplex structures, the high affinity interactions between compound 1 and the quadruplex-forming nucleic acid structures are weakly endothermic. Molecular docking studies suggest an end-stacking binding mode for compound 1 interacting with quadruplex structures, and a higher affinity for the parallel conformation of c-myc than for the mixed-hybrid conformation of 22AG. In addition, docking studies also suggest that the reduced affinity for duplex DNA structures is due to the non-viability of an intercalative binding mode
Light-Trap: A SiPM Upgrade for Very High Energy Astronomy and Beyond
With the development of the Imaging Atmospheric Cherenkov Technique (IACT),
Gamma-ray astronomy has become one of the most interesting and productive
fields of astrophysics. Current IACT telescope arrays (MAGIC, H.E.S.S, VERITAS)
use photomultiplier tubes (PMTs) to detect the optical/near-UV Cherenkov
radiation emitted due to the interaction of gamma rays with the atmosphere. For
the next generation of IACT experiments, the possibility of replacing the PMTs
with Silicon photomultipliers (SiPMs) is being studied. Among the main
drawbacks of SiPMs are their limited active area (leading to an increase in the
cost and complexity of the camera readout) and their sensitivity to unwanted
wavelengths. Here we propose a novel method to build a relatively low-cost
pixel consisting of a SiPM attached to a PMMA disc doped with a wavelength
shifter. This pixel collects light over a much larger area than a single
standard SiPM and improves sensitivity to near-UV light while simultaneously
rejecting background. We describe the design of a detector that could also have
applications in other fields where detection area and cost are crucial. We
present results of simulations and laboratory measurements of a pixel prototype
and from field tests performed with a 7-pixel cluster installed in a MAGIC
telescope camera.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC
2017), Bexco, Busan, Korea. Id:81
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