Identification of the ns and nd Rydberg states of O2 for n=3–5

The 4s‐3d and 5s‐4dRydberg complexes of diatomic oxygen have been studied by (2+1) resonance‐enhanced multiphoton ionization of the X  3∑ g − ground state of O2. We have located and identified at least two vibrational levels of each of the following states: Three of four expected 4sσ Π states; all four expected 5sσ Π states; 18 of 22 expected 3d states (with only the states of the 3dσ orbital remaining unobserved); and 5 of the 10 predicted 4dπ 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 Δv≠0 interactions which perturb the rotational structure of the 3dπ∑ and Δ states. The relative intensities of the states detected are found to span a range in excess of 104 with the nsσ Π states being the weakest and the ndπ ∑ states being the strongest. Photoionization of the ndπ ∑ 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*)−3

Identification of the nd Δ and Σ States and the 1,3Φ←←X 3Σ− g Transition of O2 by Resonant Multiphoton Ionization

Spectra of the 3dRydberg state region of O2 have been obtained by two‐photon 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 Σ, Δ, and Φ states. Earlier assignments were corrected. The Δ and Φ assignments are complete while the Σ assignments are so far incomplete

System and method for detecting cells or components thereof

A system and method for detecting a detectably labeled cell or componentthereof in a sample comprising one or more cells or components thereof, at least one cell or component thereof of which is detectably labeled with at least two detectable labels. In one embodiment, the method comprises: (i) introducing the sample into one or more flow cells of a flow cytometer, (ii) irradiating the sample with one or more light sources that are absorbed by the at least two detectable labels, the absorption of which is to be detected, and (iii) detectingsimultaneously the absorption of light by the at least two detectable labels on the detectably labeled cell or component thereof with an array of photomultiplier tubes, which are operably linked to two or more filters that selectively transmit detectable emissions from the at least two detectable labels

Method and apparatus for magnetoresistive monitoring of analytes in flow streams

Method and apparatus for manipulating and monitoring analyte flowing in fluid streams. A giant magnetoresistive sensor has an array of sensing elements that produce electrical output signals which vary in dependence on changes in the magnetic field proximate the sensing elements. The analyte is included in a stream, such that the stream has a magnetic property which is dependent on the concentration and distribution on the analyte therein. The stream is flowed past the giant magnetoresistive sensor and in sufficiently close proximity to cause the magnetic properties of the stream to produce electrical output signals. The electrical output signals are monitored as an indicator of analyte concentration or distribution in the stream flowing past the GMR sensor. Changes in the magnetic field produced by the background stream are introduced by analyte molecules, whose presence in the flow past the GMR will effect the output reading

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

Detection of Mycobacterium avium subsp. paratuberculosis by a Sonicate Immunoassay Based on Surface-Enhanced Raman Scattering▿

A sandwich immunoassay for the rapid, low-level detection of Mycobacterium avium subsp. paratuberculosis has been developed. M. avium subsp. paratuberculosis is the causative agent of Johne's disease in cattle, and one of the major obstacles in controlling the spread of this disease is the inability to rapidly detect small amounts of bacteria or other diagnostic markers shed during the subclinical stage of infection. This paper details the development and performance of an assay for sonicated M. avium subsp. paratuberculosis lysate that is based on surface-enhanced Raman scattering (SERS). There are two key components of the assay: (i) an immobilized layer of monoclonal antibodies that target a surface protein on the microorganism; and (ii) extrinsic Raman labels (ERLs) that are designed to selectively bind to captured proteins and produce large SERS signals. By correlating the number of M. avium subsp. paratuberculosis bacilli present prior to sonication to the amount of total protein in the resulting sonicate, the detection limit determined for total protein can be translated to the microorganism concentration. These findings yield detection limits of 100 and 200 ng/ml (estimated to be 500 and 1,000 M. avium subsp. paratuberculosis bacilli/ml) for sonicate spiked in phosphate buffer and sonicate spiked in whole milk, respectively. Moreover, the time required to complete the assay, which includes sample preparation, antigen extraction, ERL incubation, and readout, is less than 24 h. The potential for incorporation of this novel assay into diagnostic laboratories is also briefly discussed

Impact of Protein Shedding on Detection of Mycobacterium avium subsp. paratuberculosis by a Whole-Cell Immunoassay Incorporating Surface-Enhanced Raman Scattering▿

The etiological agent of Johne's disease is Mycobacterium avium subsp. paratuberculosis. Controlling the spread of this disease is hindered by the lack of sensitive, selective, and rapid detection methods for M. avium subsp. paratuberculosis. By using a recently optimized sandwich immunoassay (B. J. Yakes, R. J. Lipert, J. P. Bannantine, and M. D. Porter, Clin. Vaccine Immunol. 15:227-234, 2008), which incorporates a new monoclonal antibody for the selective capture and labeling of M. avium subsp. paratuberculosis and surface-enhanced Raman scattering for sensitive readout, detection limits of ∼630 and ∼740 M. avium subsp. paratuberculosis cells/ml are achieved in phosphate-buffered saline and whole milk samples, respectively, after spiking with heat-treated M. avium subsp. paratuberculosis. Surprisingly, these detection limits are 3 orders of magnitude lower than expected based on theoretical predictions. Experiments designed to determine the origin of the improvement revealed that the major membrane protein targeted by the monoclonal antibody was present in the sample suspensions as shed protein. This finding indicates that the capture and labeling of shed protein function as a facile amplification strategy for lowering the limit of detection for M. avium subsp. paratuberculosis that may also be applicable to the design of a wide range of highly sensitive assays for other cells and viruses