Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Recent multi-photon ionization (MPI) experiments on uracil revealed a fragment ion at m/z 84 that was proposed as a potential marker for ring opening in the electronically excited neutral molecule. The present MPI measurements on deuterated uracil identify the fragment as C3H4N2O+ (uracil+ less CO), a plausible dissociative ionization product from the theoretically predicted open-ring isomer. Equivalent measurements on thymine do not reveal an analogous CO loss channel, suggesting greater stability of the excited DNA base. MPI and electron impact ionization experiments have been carried out on uracil-adenine clusters in order to better understand the radiation response of uracil within RNA. Evidence for C3H4N2O+ production from multi-photon-ionized uracil-adenine clusters is tentatively attributed to a significant population of π-stacked configurations in the neutral beam

Comparative Morphological Studies on Lyssa in Carnivores and Camels with Special Reference to Its Surgical Resection

The lyssa is a morphologically supporting structure situated along the median plan on the ventral surface of the apex of the tongue in some animals. The present study aimed to describe the morphological differences of the lyssa in carnivores (dog and cat) and camel using conformist macroscopic and microscopic methods as well as evaluation of its surgical resection in the dog and cat. The lyssa is a rod-shaped in dog, strip like structure in cat and ridge-like structure in camel. It showed straight course in dog and helical appearance in cat. In the studied species, the lyssa was formed from adipose tissue intermingled with irregular connective tissue. However, dense striated muscles fibers were seen in the caudal half of the lyssa in dog. Besides, few bundles of longitudinally running muscle fibers were observed in cat and camel. In dog, the lyssa was defined by a coarse sheath of connective tissue, this capsule was ill-defined in cat and absent in camel. In cat, a pyramidal extension of the adipose tissue of the lyssa was attached to intrinsic striated muscle of the tongue. Full function of the tongue could be achieved after surgical resection of lyssa in dogs and cats

Analysis of Tangential Slot Blowing on F/A-18 Isolated Forebody

The generation of significant side forces and yawing moments on an F/A-18 fuselage through tangential slot blowing is analyzed using computational fluid dynamics. The effects of freestream Mach number, jet exit conditions, jet length, and jet location are studied. The effects of over- and underblowing on force and moment production are analyzed. Non-time-accurate solutions are obtained to determine the steady-state side forces, yawing moments, and surface pressure distributions generated by tangential slot blowing. Time-accurate solutions are obtained to study the force onset time lag of tangential slot blowing. Comparison with available experimental data from full-scale wind-tunnel and subscale wind-tunnel tests are made. This computational analysis complements the experimental results and provides a detailed understanding of the effects of tangential slot blowing on the flowfield about the isolated F/A-18 forebody. Additionally, it extends the slot-blowing database to transonic maneuvering Mach numbers

Development of two reference materials for all trans-retinol, retinyl palmitate, α- and γ-tocopherol in milk powder and infant formula

AbstractVitamins are important food constituents that can be present in almost every foodstuff. Food quality and safety depends on food surveillance by reliable quantitative analysis enabled by appropriate quality control. Certified matrix reference materials are versatile tools to support quality assurance and control. However, in the case of vitamins, which are important in various foods, there is a lack of matrix reference materials. Two certified reference materials for the determination of all–trans-retinol, retinyl palmitate, and α- and γ-tocopherol in milk powder and infant formula have been developed by the National Institute of Standards, Egypt. This article presents the preparation, characterization, homogeneity, and stability testing as well as statistical treatment of data and certified value assignment. The assignment of the certified values and associated uncertainties in the prepared natural-matrix reference materials were based on the widely used approach of combining data from independent and reliable analytical methods

Thin-film ZnO charge-trapping memory cell grown in a single ALD step

Cataloged from PDF version of article.A thin-film ZnO-based single-transistor memory cell with a gate stack deposited in a single atomic layer deposition step is demonstrated. Thin-film ZnO is used as channel material and charge-trapping layer for the first time. The extracted mobility and subthreshold slope of the thin-film device are 23 cm2/V · s and 720 mV/dec, respectively. The memory effect is verified by a 2.35-V hysteresis in the Idrain–Vgate curve. Physics-based TCAD simulations show very good agreement with the experimental results providing insight to the charge-trapping physics

Toroidal MHD equilibria and classical diffusion in complex magnetic configurations

Ideal MHD equilibrium for toroidal plasma situated in a magnetic field with single non-planar magnetic axis with variable torsion and curvature is investigated. The plasma is taken to have a non-circular cross section (elliptically or triangularly deformed) through which a longitudinal current with a flat profile flows. Equilibria of the Tokamak or French Harmonica types are examined as special cases of the general class and it is shown that for a given longitudinal current and torsion of the magnetic axis the effect of triangular deformation on the limiting value of beta (the ratio of kinetic to magnetic pressure) is weak and can be neglected. Vertically elongated elliptical deformation of the plasma cross section is shown to lead to an increase in the limiting value of beta relative to that of a circular cross section. Moreover, classical diffusion of non-axisymmetric toroidal plasma is examined with the result that vertical elongation tends to decrease diffusion while triangular deformation appears to show an effect only at high beta .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48947/2/ppv17i12p1049.pd

Toroidal MHD stability in complex magnetic configurations

Mercier's localized perturbation criterion near the magnetic axis is examined for a particular type of toroidal configuration of non-planar magnetic axis of variable curvature and torsion with non-circular (elliptically and triangularly deformed) plasma cross section for the 'resonance case'. As an application, a numerical calculation is carried out for a class of equilibria that belongs to the above configuration with constant torsion. In the absence of longitudinal current, it is possible to have a domain of stability in a system with a horizontally elliptical (and triangular) deformation with an ellipticity corresponding to (a=2b) i.e. the minor axis is twice the major axis. In the presence of a longitudinal current, a domain of stability is also possible and it depends on the direction of the current. Horizontally elliptical and triangular deformations are favourable for stability.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48949/2/ppv19i10p969.pd

Electroluminescence efficiencies of erbium in silicon-based hosts

International audienceWe report on room-temperature 1.5 lm electroluminescence from trivalent erbium (Er3þ) ionsembedded in three different CMOS-compatible silicon-based hosts: SiO2, Si3N4, and SiNx. We showthat although the insertion of either nitrogen or excess silicon helps enhance electrical conductionand reduce the onset voltage for electroluminescence, it drastically decreases the external quantumefficiency of Er3þ ions from 2% in SiO2 to 0.001% and 0.0004% in SiNx and Si3N4, respectively.Furthermore, we present strong evidence that hot carrier injection is significantly more efficient thandefect-assisted conduction for the electrical excitation of Er3þ ions. These results suggest strategiesto optimize the engineering of on-chip electrically excited silicon-based nanophotonic light sources

OSIRIS-Rex OCAMS Detector Assembly Characterization

The OSIRIS-REx asteroid sample return mission carries a suite of three cameras referred to as OCAMS. The Space Dynamics Laboratory (SDL) at Utah State University is providing the CCD-based detector assemblies for OCAMS to the Lunar Planetary Lab (LPL) at the University of Arizona. Working with the LPL, SDL has designed the electronics to operate a 1K by 1K frame transfer Teledyne DALSA Multi-Pinned Phase (MPP) CCD. The detector assembly electronics provides the CCD clocking, biasing, and digital interface with the OCAMS payload Command Control Module (CCM). A prototype system was built to verify the functionality of the detector assembly design and to characterize the detector system performance at the intended operating temperatures. The characterization results are described in this paper