67 research outputs found
Identification of the ns and nd Rydberg states of O2 for n=3â5
The 4sâ3d and 5sâ4dRydberg complexes of diatomic oxygen have been studied by (2+1) resonanceâenhanced multiphoton ionization of the Xâ 3â g â ground state of O2. We have located and identified at least two vibrational levels of each of the following states: Three of four expected 4sĎ Î states; all four expected 5sĎ Î states; 18 of 22 expected 3d states (with only the states of the 3dĎ orbital remaining unobserved); and 5 of the 10 predicted 4dĎ states. State assignments were assisted by the following: the results of rotational cooling and laser polarization experiments which facilitated the rotational analysis, band positions, band intensities, and parameterized calculations. The experimentally determined state locations are compared with the state locations obtained from ab initio calculations. We have carried out isotope experiments and rotational linewidth analysis to study in some detail the mixing between the Rydberg states and the repulsive valence states as well as the mixing between the Rydberg states themselves. We conclude that direct predissociation dominates indirect predissociation as a dissociative mechanism, but there is evidence of Îvâ 0 interactions which perturb the rotational structure of the 3dĎâ and Î states. The relative intensities of the states detected are found to span a range in excess of 104 with the nsĎ Î states being the weakest and the ndĎ â states being the strongest. Photoionization of the ndĎ â states appears to be most affected by the shape resonance in the continuum. Our measurements confirm the expectation that many of the properties of the Rydberg states in the same series scale as (n*)â3
Identification of the nd Î and ÎŁ States and the 1,3ÎŚââXâ 3ÎŁâ g Transition of O2 by Resonant Multiphoton Ionization
Spectra of the 3dRydberg state region of O2 have been obtained by twoâphoton resonant ionization of the ground electronic state. By varying the rotational distribution and radiation polarization, all observed bands were identified and attributed to excitation of ÎŁ, Î, and ÎŚ states. Earlier assignments were corrected. The Î and ÎŚ assignments are complete while the ÎŁ assignments are so far incomplete
In-Flight Water Quality Monitoring on the International Space Station (ISS): Measuring Biocide Concentrations with Colorimetric Solid Phase Extraction (CSPE)
The colorimetric water quality monitoring kit (CWQMK) was delivered to the International Space Station (ISS) on STS-128/17A and was initially deployed in September 2009. The kit was flown as a station development test objective (SDTO) experiment to evaluate the acceptability of colorimetric solid phase extraction (CSPE) technology for routine water quality monitoring on the ISS. During the SDTO experiment, water samples from the U.S. water processor assembly (WPA), the U.S. potable water dispenser (PWD), and the Russian system for dispensing ground-supplied water (SVO-ZV) were collected and analyzed with the CWQMK. Samples from the U.S. segment of the ISS were analyzed for molecular iodine, which is the biocide added to water in the WPA. Samples from the SVOZV system were analyzed for ionic silver, the biocide used on the Russian segment of the ISS. In all, thirteen in-flight analysis sessions were completed as part of the SDTO experiment. This paper provides an overview of the experiment and reports the results obtained with the CWQMK. The forward plan for certifying the CWQMK as operational hardware and expanding the capabilities of the kit are also discussed
Continuum Extrapolation of Moments of Nucleon Quark Distributions in Full QCD
Moments of light cone quark density, helicity, and transversity distributions are calculated in unquenched lattice QCD at and using Wilson fermions on lattices. These results are combined with earlier calculations at using SESAM configurations to study the continuum limit
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Optical assay technology for safeguards
Research conducted in the Ames Laboratory Nuclear Safeguards and Security Program during the period July 1, 1990 to September 30, 1990 is reviewed; included are reprints and preprints of papers written during this quarter. The first demonstration of isotopic selectivity in Inductively Coupled Plasma -- Laser Excited Atomic Fluorescence Spectroscopy (ICP-LEAFS) is reported and the application of ICP-LEAFS to U isotopic analysis is discussed. Current work in applying optical spectroscopy to the analytical determination of gas phase metal atoms is reviewed. Program administration topics are included in a separately bound Management Supplement to this report
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Continuum Extrapolation of Moments Nucleon Quark Distributions in Full QCD
Moments of light cone quark density, helicity, and transversity distributions are calculated in unquenched lattice QCD at {beta} = 5.5 and {beta} = 5.3 using Wilson fermions on 16{sup 3} x 32 lattices. These results are combined with earlier calculations at {beta} = 5.6 using SESAM configurations to study the continuum limit
Continuum extrapolation of moments of nucleon quark distributions in full QCD
Moments of light cone quark density, helicity, and transversity distributions
are calculated in unquenched lattice QCD at and
using Wilson fermions on lattices. These results are
combined with earlier calculations at using SESAM configurations
to study the continuum limit.Comment: Lattice 2002 (hadronic matrix elements) 3 pages, 1 figur
Effect of silver nanoparticles on human primary keratinocytes
Abstract
Silver nanoparticles (AgNPs) have many biological applications in biomedicine, biotechnology and other life sciences. Depending on the size, shape and the type of carrier, AgNPs demonstrate different physical and chemical properties. AgNPs have strong antimicrobial, antiviral and antifungal activity, thus they are used extensively in a range of medical settings, particularly in wound dressings but also in cosmetics. This study was undertaken to examine the potential toxic effects of 15 nm polyvinylpyrrolidone-coated AgNPs on primary normal human epidermal keratinocytes (NHEK). Cells were treated with different concentrations of AgNPs and then cell viability, metabolic activity and other biological and biochemical aspects of keratinocytes functioning were studied. We observed that AgNPs decrease keratinocyte viability, metabolism and also proliferatory and migratory potential of these cells. Moreover, longer exposure resulted in activation of caspase 3/7 and DNA damage. Our studies show for the first time, that AgNPs may present possible danger for primary keratinocytes, concerning activation of genotoxic and cytotoxic processes depending on the concentration.</jats:p
Design, Certification, and Deployment of the Colorimetric Water Quality Monitoring Kit (CWQMK)
In August 2009, an experimental water quality monitoring kit based on Colorimetric Solid Phase Extraction (CSPE) technology was delivered to the International Space Station (ISS) aboard STS-128/17A. The kit, called the Colorimetric Water Quality Monitoring Kit (CWQMK), was developed by a team of scientists and engineers from NASA s Habitability and Environmental Factors Division in the Space Life Sciences Directorate at Johnson Space Center, the Wyle Integrated Science and Engineering Group in Houston, Texas, the University of Utah, and Iowa State University. The CWQMK was flown and deployed as a Station Development Test Objective (SDTO) experiment on ISS. The goal of the SDTO experiment was to evaluate the acceptability of CSPE technology for routine water quality monitoring on ISS. This paper provides an overview of the SDTO experiment, as well as a detailed description of the CWQMK hardware and a summary of the testing and analysis conducted to certify the CWQMK for use on ISS. The results obtained from the SDTO experiment are also reported and discussed in detail
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