Publications by authors named "John T Kelly"

21 Publications

  • Page 1 of 1

Improving Quantification of tabun, sarin, soman, cyclosarin, and sulfur mustard by focusing agents: A field portable gas chromatography-mass spectrometry study.

J Chromatogr A 2021 Jan 13;1636:461784. Epub 2020 Dec 13.

Hazardous Materials Research Center (HMRC), Battelle Columbus Laboratories, Battelle Memorial Institute, Columbus, OH, USA.

Commercial gas chromatograph-mass spectrometers, one of which being Inficon's HAPSITE® ER, have demonstrated chemical detection and identification of nerve agents (G-series) and blistering agents (mustard gas) in the field; however most analyses relies on self-contained or external calibration that inherently drifts over time. We describe an analytical approach that uses target-based thermal desorption standards, called focusing agents, to accurately calculate concentrations of chemical warfare agents that are analyzed by gas chromatograph-mass spectrometry. Here, we provide relative response factors of focusing agents (2-chloroethyl ethyl sulfide, diisopropyl fluorophosphate, diethyl methylphosphonate, diethyl malonate, methyl salicylate, and dichlorvos) that are used to quantify concentrations of tabun, sarin, soman, cyclosarin and sulfur mustard loaded on thermal desorption tubes (Tenax® TA). Aging effects of focusing agents are evaluated by monitoring deviations in quantification as thermal desorption tubes age in storage at room temperature and relative humidity. The addition of focusing agents improves the quantification of tabun, sarin, soman, cyclosarin and sulfur mustard that is analyzed within the same day as well as a 14-day period. Among the six focusing agents studied here, diisopropyl fluorophosphate has the best performance for nerve agents (G-series) and blistering agents (mustard gas) compared to other focusing agents in this work and is recommended for field use for quantification. The use of focusing agent in the field leads to more accurate and reliable quantification of Tabun (GA), Sarin (GB), Soman (GD), Cyclosarin (GF) and Sulfur Mustard (HD) than the traditional internal standard. Future improvements on the detection of chemical, biological, radiological, nuclear, and explosive materials (CBRNE) can be safely demonstrated with standards calibrated for harmful agents.
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http://dx.doi.org/10.1016/j.chroma.2020.461784DOI Listing
January 2021

Integrating physiological data with the conservation and management of fishes: a meta-analytical review using the threatened green sturgeon ().

Conserv Physiol 2019 28;7(1):coz035. Epub 2019 Jun 28.

Wildlife, Fish and Conservation Biology, University of California Davis, One Shields Ave., Davis, CA, USA.

Reversing global declines in the abundance and diversity of fishes is dependent on science-based conservation solutions. A wealth of data exist on the ecophysiological constraints of many fishes, but much of this information is underutilized in recovery plans due to a lack of synthesis. Here, we used the imperiled green sturgeon () as an example of how a quantitative synthesis of physiological data can inform conservation plans, identify knowledge gaps and direct future research actions. We reviewed and extracted metadata from peer-reviewed papers on green sturgeon. A total of 105 publications were identified, spanning multiple disciplines, with the primary focus being conservation physiology (23.8%). A meta-analytical approach was chosen to summarize the mean effects of prominent stressors (elevated temperatures, salinity, low food availability and contaminants) on several physiological traits (growth, thermal tolerance, swimming performance and heat shock protein expression). All examined stressors significantly impaired green sturgeon growth, and additional stressor-specific costs were documented. These findings were then used to suggest several management actions, such as mitigating salt intrusion in nursery habitats and maintaining water temperatures within optimal ranges during peak spawning periods. Key data gaps were also identified; research efforts have been biased towards juvenile (38.1%) and adult (35.2%) life-history stages, and less data are available for early life-history stages (embryonic, 11.4%; yolk-sac larvae, 12.4%; and post yolk-sac larvae, 16.2%). Similarly, most data were collected from single-stressor studies (91.4%) and there is an urgent need to understand interactions among stressors as anthropogenic change is multi-variate and dynamic. Collectively, these findings provide an example of how meta-analytic reviews are a powerful tool to inform management actions, with the end goal of maximizing conservation gains from research efforts.
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http://dx.doi.org/10.1093/conphys/coz035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6601218PMC
June 2019

Communication: Gas phase vibrational spectroscopy of the azide-water complex.

J Chem Phys 2018 Nov;149(19):191101

Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universitat Leipzig, Linnéstraße 2, D-04103 Leipzig, Germany.

The vibrational spectra of the azide-water complex, N(HO), and its fully deuterated isotopologue are studied using infrared photodissociation (IRPD) spectroscopy (800-3800 cm) and high-level computations. The IRPD spectrum of the H-tagged complex exhibits four fundamental transitions at 3705, 3084, 2003, and 1660 cm, which are assigned to the free OH stretching, the hydrogen-bonded O-H stretching, the antisymmetric N stretching, and the water bending mode, respectively. The IRPD spectrum is consistent with a planar, singly hydrogen-bonded structure according to an MP2 and CCSD(T) anharmonic analysis via generalized second-order vibrational perturbation theory. The red-shift of the hydrogen-bonded OH stretching fundamental of 623 cm associated with this structure is computed within 6 cm (or 1%) and is used to estimate the proton affinity of azide (1410 kJ mol). Born-Oppenheimer molecular dynamics simulations show that large amplitude motions are responsible for the observed band broadening at cryogenic temperature. Temperature-dependent (6-300 K) IR multiphoton dissociation spectra of the untagged complex are also presented and discussed in the context of spectral diffusion observed in the condensed phase.
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http://dx.doi.org/10.1063/1.5053671DOI Listing
November 2018

Structure and Reactivity of Al-O(H)-Al Moieties in Siloxide Frameworks: Solution and Gas-Phase Model Studies.

Angew Chem Int Ed Engl 2019 Jan 17;58(3):902-906. Epub 2018 Dec 17.

Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany.

Even though aluminas and aluminosilicates have found widespread application, a consistent molecular understanding of their surface heterogeneity and the behavior of defects resulting from hydroxylation/dehydroxylation remains unclear. Here, we study the well-defined molecular model compound, [Al (μ -OH) (THF) (PhSi(OSiPh O) ) ], 1, to gain insight into the acid-base reactivity of cyclic trinuclear Al (μ -OH) moieties at the atomic level. We find that, like zeolites, they are sufficiently acidic to catalyze the isomerization of olefins. DFT and gas phase vibrational spectroscopy on solvent-free and deprotonated 1 show that the six-membered ring structure of its Al (μ -OH) core is unstable with respect to deprotonation of one of its hydroxy groups and rearranges into two edge-sharing four-membered rings. This renders Al -O(H)-Al units strong acid sites, and all results together suggest that their acidity is similar to that of zeolitic Si -O(H)-Al groups.
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http://dx.doi.org/10.1002/anie.201810130DOI Listing
January 2019

Dynamics of Gene Expression Responses for Ion Transport Proteins and Aquaporins in the Gill of a Euryhaline Pupfish during Freshwater and High-Salinity Acclimation.

Physiol Biochem Zool 2018 Nov/Dec;91(6):1148-1171

Pupfishes (genus Cyprinodon) evolved some of the broadest salinity tolerances of teleost fishes, with some taxa surviving in conditions from freshwater to nearly 160 ppt. In this study, we examined transcriptional dynamics of ion transporters and aquaporins in the gill of the desert Amargosa pupfish (Cyprinodon nevadensis amargosae) during rapid salinity change. Pupfish acclimated to 7.5 ppt were exposed to freshwater (0.3 ppt), seawater (35 ppt), or hypersaline (55 ppt) conditions over 4 h and sampled at these salinities over 14 d. Plasma osmolality and Cl concentration became elevated 8 h after the start of exposure to 35 or 55 ppt but returned to baseline levels after 14 d. Osmolality recovery was paralleled by increased gill Na/K-ATPase activity and higher relative levels of messenger RNAs (mRNAs) encoding cystic fibrosis transmembrane conductance regulator (cftr) and Na/K/2Cl cotransporter-1 (nkcc1). Transcripts encoding one Na-HCO cotransporter-1 isoform (nbce1.1) also increased in the gills at higher salinities, while a second isoform (nbce1.2) increased expression in freshwater. Pupfish in freshwater also had lower osmolality and elevated gill mRNAs for Na/H exchanger isoform-2a (nhe2a) and V-type H-ATPase within 8 h, followed by increases in Na/H exchanger-3 (nhe3), carbonic anhydrase 2 (ca2), and aquaporin-3 (aqp3) within 1 d. Gill mRNAs for Na/Cl cotransporter-2 (ncc2) also were elevated 14 d after exposure to 0.3 ppt. These results offer insights into how coordinated transcriptional responses for ion transporters in the gill facilitate reestablishment of osmotic homeostasis after changes in environmental salinity and provide evidence that the teleost gill expresses two Na-HCO cotransporter-1 isoforms with different roles in freshwater and seawater acclimation.
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http://dx.doi.org/10.1086/700432DOI Listing
January 2019

Probing the propensity of perchlorate anions for surface solvation by infrared photodissociation spectroscopy.

J Chem Phys 2018 Jun;148(22):222840

Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, D-04103 Leipzig, Germany.

We investigate the perchlorate anion, ClO, microhydrated with up to eight water molecules using infrared photodissociation (IRPD) spectroscopy aided by density functional theory computations. The features observed in the IRPD spectra of D-tagged ClO(HO) with n = 0-8 in the O-H stretching (2800-3800 cm) and fingerprint (800-1800 cm) spectral ranges are assigned to vibrational modes of the solvent, i.e., free and hydrogen-bonded O-H stretching and HO bending modes, and of the solute, i.e., perchlorate stretching modes. The splitting of the triply degenerate antisymmetric stretching mode in the bare ClO (1102 cm) upon microhydration directly reports on the symmetry of the local solvation network, while the red-shift of the hydrogen-bonded O-H stretching bands in comparison to those of free O-H oscillators (>3700 cm) reflects the strength of the anion-water (3550-3650 cm) and water-water (3240-3540 cm) hydrogen bonds. The stronger water-water interaction leads to an early onset of water-water hydrogen bond formation (n = 2) and eventually asymmetric solvation of ClO, evidenced by the population of the second and third hydration shells at n = 5 and n = 8, respectively, before the first hydration shell is completed. The present study provides a bottom-up view of the initial stages of hydrogen-bond network formation around a high surface propensity anion, and these insights are discussed in the context of recent results obtained for the water-vapor interface of perchlorate solutions.
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http://dx.doi.org/10.1063/1.5028416DOI Listing
June 2018

Isolating the Isomeric Hydrogen Bonding Signatures of the Cyanide-Water Complex by Cryogenic Ion Trap Vibrational Spectroscopy.

J Phys Chem Lett 2017 Nov 20;8(21):5349-5354. Epub 2017 Oct 20.

Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig , Linnéstraße 2, D-04103 Leipzig, Germany.

The vibrational spectroscopy of the cyanide-water complex and its fully deuterated isotopologue is studied in the spectral range from 800 to 3800 cm. Infrared/infrared double-resonance population labeling spectroscopy of the cryogenically cooled, messenger-tagged complexes isolates the spectral signature of the two quasi-isoenergetic, singly hydrogen-bonded isomers HOH···NC and HOH···CN. The infrared photodissociation spectra are assigned based on a comparison to simulated anharmonic spectra. Infrared multiple photon dissociation spectra in the temperature range from 6 to 300 K confirm the stability of the two isomers at lower temperatures and provide evidence for a considerably more dynamic structure, also involving doubly hydrogen-bonded configurations, at higher internal energies. The observed red shifts Δν of the hydrogen-bonded O-H stretches, 671 cm (HOH···NC) and 812 cm (HOH···CN), confirm the universal correlation of Δν with the corresponding proton affinities.
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http://dx.doi.org/10.1021/acs.jpclett.7b02263DOI Listing
November 2017

Probing Dative and Dihydrogen Bonding in Ammonia Borane with Electronic Structure Computations and Raman under Nitrogen Spectroscopy.

J Phys Chem A 2017 Aug 11;121(31):5884-5893. Epub 2017 Jul 11.

Department of Chemistry and Biochemistry, University of Mississippi, University , Mississippi 38677-1848, United States.

Although ammonia borane is isoelectronic with ethane and they have similar structures, BHNH exhibits rather atypical bonding compared to that in CHCH. The central bond in ammonia borane is actually a coordinate covalent or dative bond rather than the conventional covalent C-C bond in ethane where each atom donates one electron. In addition, strong intermolecular dihydrogen bonds can form between two or more ammonia borane molecules compared to the relatively weak dispersion forces between ethane molecules. As a result, ammonia borane's physical properties are very sensitive to the environment. For example, gas-phase and solid-state ammonia borane have very different BN bond lengths and BN stretching frequencies, which led to much debate in the literature. It has been demonstrated that the use of cluster models based on experimental crystal structures led to better agreement between theory and experiment. Here, we employ a variety of cluster models to track how the interaction energies, bond lengths, and vibrational normal modes evolve with the size and structural characteristics of the clusters. The M06-2X/6-311++G(2df,2pd) level of theory was selected for this analysis on the basis of favorable comparison with CCSD(T)/aug-cc-pVTZ data for the ammonia borane monomer and dimer. Fourteen unique fully optimized molecular cluster geometries, (BHNH), and nine crystal models, (BHNH), were used to elucidate how the local environment impacts ammonia borane's physical properties. Computational results for the BN stretching frequencies are also compared directly to the Raman spectrum of solid ammonia borane at 77 K using Raman under liquid nitrogen spectroscopy (RUNS). A strong linear correlation was found to exist between the BN bond length and stretching frequency, from an isolated monomer to the most distorted BHNH unit in a cluster or crystal structure model. Excellent agreement was seen between the frequencies computed for the largest crystal model and the RUNS experimental spectra (typically within a few wavenumbers).
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http://dx.doi.org/10.1021/acs.jpca.7b03509DOI Listing
August 2017

A Facile Electrochemical Reduction Method for Improving Photocatalytic Performance of α-FeO Photoanode for Solar Water Splitting.

ACS Appl Mater Interfaces 2017 Jan 5;9(1):381-390. Epub 2017 Jan 5.

Department of Chemistry, Tulane University , New Orleans, Louisiana 70118, United States.

Electrochemical reduction method is used for the first time to significantly improve the photo-electrochemical performance of α-FeO photoanode prepared on fluorine-doped tin oxide substrates by spin-coating aqueous solution of Fe(NO) followed by thermal annealing in air. Photocurrent density of α-FeO thin film photoanode can be enhanced 25 times by partially reducing the oxide film to form more conductive FeO (magnetite). FeO helps facilitate efficient charge transport and collection from the top α-FeO layer upon light absorption and charge separation to yield enhanced photocurrent density. The optimal enhancement can be obtained for <50 nm films because of the short charge transport distance for the α-FeO layer. Thick α-FeO films require more charge and overpotential than thinner films to achieve limited enhancement because of the sluggish charge transport over a longer distance to oxidize water. Electrochemical reduction of α-FeO in unbuffered pH-neutral solution yields much higher but unstable photocurrent enhancement because of the increase in local pH value accompanied by proton reduction at a hematite surface.
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http://dx.doi.org/10.1021/acsami.6b11057DOI Listing
January 2017

Competition between Hydrophilic and Argyrophilic Interactions in Surface Enhanced Raman Spectroscopy.

Chemphyschem 2016 Sep 7;17(18):2782-6. Epub 2016 Jul 7.

Department of Chemistry and Biochemistry, University of Mississippi, P.O. Box 1848, University, Mississippi, 38677, United States.

The competition for binding and charge-transfer (CT) from the nitrogen containing heterocycle pyrimidine to either silver or to water in surface enhanced Raman spectroscopy (SERS) is discussed. The correlation between the shifting observed for vibrational normal modes and CT is analyzed both experimentally using Raman spectroscopy and theoretically using electronic structure theory. Discrete features in the Raman spectrum correspond to the binding of either water or silver to each of pyrimidine's nitrogen atoms with comparable frequency shifts. Natural bond orbital (NBO) calculations in each chemical environment reveal that the magnitude of charge transfer from pyrimidine to adjacent silver atoms is only about twice that for water alone. These results suggest that the choice of solvent plays a role in determining the vibrational frequencies of nitrogen containing molecules in SERS experiments.
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http://dx.doi.org/10.1002/cphc.201600678DOI Listing
September 2016

Recent Advancements in Chemical Physics.

J Phys Chem A 2015 Dec;119(52):12909-10

Department of Chemistry and Biochemistry, University of Mississippi, University , Oxford, Mississippi 38677, United States.

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http://dx.doi.org/10.1021/acs.jpca.5b12096DOI Listing
December 2015

Water network-mediated, electron-induced proton transfer in [C5H5N ⋅ (H2O)n](-) clusters.

J Chem Phys 2015 Oct;143(14):144305

Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, USA.

The role of proton-assisted charge accommodation in electron capture by a heterocyclic electron scavenger is investigated through theoretical analysis of the vibrational spectra of cold, gas phase [Py ⋅ (H2O)n=3-5](-) clusters. These radical anions are formed when an excess electron is attached to water clusters containing a single pyridine (Py) molecule in a supersonic jet ion source. Under these conditions, the cluster ion distribution starts promptly at n = 3, and the photoelectron spectra, combined with vibrational predissociation spectra of the Ar-tagged anions, establish that for n > 3, these species are best described as hydrated hydroxide ions with the neutral pyridinium radical, PyH((0)), occupying one of the primary solvation sites of the OH(-). The n = 3 cluster appears to be a special case where charge localization on Py and hydroxide is nearly isoenergetic, and the nature of this species is explored with ab initio molecular dynamics calculations of the trajectories that start from metastable arrangements of the anion based on a diffuse, essentially dipole-bound electron. These calculations indicate that the reaction proceeds via a relatively slow rearrangement of the water network to create a favorable hydration configuration around the water molecule that eventually donates a proton to the Py nitrogen atom to yield the product hydroxide ion. The correlation between the degree of excess charge localization and the evolving shape of the water network revealed by this approach thus provides a microscopic picture of the "solvent coordinate" at the heart of a prototypical proton-coupled electron transfer reaction.
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http://dx.doi.org/10.1063/1.4931928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4605626PMC
October 2015

The onset of electron-induced proton-transfer in hydrated azabenzene cluster anions.

Phys Chem Chem Phys 2016 Jan;18(2):704-12

Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677, USA.

The prospect that protons from water may be transferred to N-heterocyclic molecules due to the presence of an excess electron is studied in hydrated azabenzene cluster anions using anion photoelectron spectroscopy and computational chemistry. In the case of s-triazine (C3H3N3), which has a positive adiabatic electron affinity, proton transfer is not energetically favored nor observed experimentally. Heterocyclic rings with only 1 or 2 nitrogen atoms have negative electron affinities, but the addition of solvating water molecules can yield stable negative ions. In the case of the diazines (C4H4N2: pyrazine, pyrimidine, and pyridazine) the addition of one water molecule is enough to stabilize the negative ion, with the majority of the excess electron density in a π* orbital of the heterocycle but not significantly extended over the hydrogen bonded water network. Pyridine (C5H5N), with the most negative electron affinity, requires three water molecules to stabilize its negative ion. Although our computations suggest proton transfer to be energetically viable in all five N-heterocyclic systems studied here when three or more water molecules are present, proton transfer is not observed experimentally in the triazine nor in the diazine series. In pyridine, however, proton transfer competes energetically with hydrogen bonding (solvation), when three water molecules are present, i.e., both motifs are observed. Pyridine clusters containing four or more water molecules almost exclusively exhibit proton transfer along with solvated [C(6-x)H(6-x+1)N(x)·OH](-) ions.
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http://dx.doi.org/10.1039/c5cp02746bDOI Listing
January 2016

Synthesis, characterization, photophysical properties, and catalytic activity of an SCS bis(N-heterocyclic thione) (SCS-NHT) Pd pincer complex.

Dalton Trans 2015 Aug;44(32):14475-82

Department of Chemistry, Mississippi State University, Mississippi State. and MS 39762 and Department of Chemistry and Biochemistry, The University of Mississippi, University, MS 38677, USA.

Treatment of 1,3-bis(3'-butylimidazolyl-1'-yl)benzene diiodide with elemental sulfur in the presence of a base produced a bis(N-heterocyclic thione) (NHT) pincer ligand precursor. Its reaction with PdCl2(CH3CN)2 produced chloro[1,3-bis(3'-butylimidazole-2'-thione-κ-S)benzene-κ-C]palladium(ii), a 6,6-fused ring SCS-NHT palladium pincer complex. This air stable compound is, to our knowledge, the first SCS pincer complex that utilizes N-heterocyclic thione (NHT) donor groups. The molecular structures of the ligand precursor and the palladium complex were determined by X-ray crystallography and computational studies provided insight into the interconversion between its rac and meso conformations. The photophysical properties of the complex were established, and its catalytic activity in Suzuki, Heck, and Sonogashira cross-coupling reactions was evaluated.
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http://dx.doi.org/10.1039/c4dt03324hDOI Listing
August 2015

Photoelectron spectroscopic and computational study of hydrated pyrimidine anions.

J Phys Chem A 2014 Dec 30;118(51):11901-7. Epub 2014 Jun 30.

Department of Chemistry and Biochemistry, University of Mississippi , P.O. Box 1848, University, Mississippi 38677, United States.

The stabilization of the pyrimidine anion by the addition of water molecules is studied experimentally using photoelectron spectroscopy of mass-selected hydrated pyrimidine clusters and computationally using quantum-mechanical electronic structure theory. Although the pyrimidine molecular anion is not observed experimentally, the addition of a single water molecule is sufficient to impart a positive electron affinity. The sequential hydration data have been used to extrapolate to -0.22 eV for the electron affinity of neutral pyrimidine, which agrees very well with previous observations. These results for pyrimidine are consistent with previous studies of the hydrated cluster anions of uridine, cytidine, thymine, adenine, uracil, and naphthalene. This commonality suggests a universal effect of sequential hydration on the electron affinity of similar molecules.
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http://dx.doi.org/10.1021/jp504724vDOI Listing
December 2014

Interaction between allergy and innate immunity: model for eosinophil regulation of epithelial cell interferon expression.

Ann Allergy Asthma Immunol 2013 Jul;111(1):25-31

Division of Allergy, Pulmonary and Critical Care, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA.

Background: Eosinophils in asthmatic airways are associated with risk of exacerbations. The most common cause of asthma exacerbations is viral respiratory infections, particularly human rhinovirus (HRV).

Objective: To determine the mechanism by which eosinophils may influence virus-induced responses.

Methods: We used an in vitro coculture model of primary human eosinophils and the BEAS-2B epithelial cell line either stimulated with HRV1A infection or polyinosinic-polycytidylic acid (poly[I:C]). The messenger RNA (mRNA) expression of interferon (IFN) β1 and IFN-λ1 was assessed by quantitative reverse-transcriptase polymerase chain reaction and the protein level of IFN- λ1 by enzyme-linked immunosorbent assay.

Results: Both poly(I:C) and HRV1A infection induced BEAS-2B expression of IFN-β1 and IFN-λ1 mRNA. Coculture of eosinophils resulted in suppression of poly(I:C)-stimulated IFN-β1 and IFN-λ1 mRNA expression (2.5-fold and 3.6-fold less, respectively). Separation of cells did not block eosinophil regulatory activity. Coculture of eosinophils with HRV1A-infected BEAS-2B cells also suppressed IFN-β1 and IFN-λ1 mRNA (5.7-fold and 5.0-fold less, respectively) and reduced IFN-λ1 protein secretion (1.6-fold decrease). This corresponded to a 34% increase in the quantity of HRV1A virus RNA on coculture with eosinophils. Recombinant transforming growth factor β suppressed IFN-λ1 from HRV1A-infected BEAS-2B cells. Coculture of eosinophils and BEAS-2B cells induced transforming growth factor β secretion, which may mediate suppression of HRV-induced interferon expression.

Conclusion: Eosinophils suppressed HRV-induced expression of interferons from epithelial cells, resulting in increased quantity of HRV. This represents one mechanism for interaction between allergic inflammation and innate immunity.
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http://dx.doi.org/10.1016/j.anai.2013.05.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3708694PMC
July 2013

Platinum CCC-NHC benzimidazolyl pincer complexes: synthesis, characterization, photostability, and theoretical investigation of a blue-green emitter.

Dalton Trans 2013 Jun 3;42(24):8820-6. Epub 2013 May 3.

Department of Chemistry and Biochemistry, The University of Mississippi, University, Mississippi 38677, USA.

The recently reported metallation/transmetallation route for the synthesis of CCC-bis(NHC) pincer ligand architectures was extended to 1,3-bis(3'-(trimethylsilylmethyl)-benzimidizol-1'-yl)benzene. The precursor was metallated with Zr(NMe2)4 and transmetallated to Pt using [Pt(COD)Cl2]. This Pt complex was found to resist photobleaching under UV irradiation in ambient conditions. Density functional theory (DFT) computations were used to generate the emission spectrum of the complex and reveal that this spectrum is the result of a transition from the triplet excited state (T1) to the ground state (S0). The Pt complex's molecular structure was determined by X-ray crystallography. The UV-vis absorption and emission spectra in solution and the solid-state emission spectra are reported. The solid-state photostability data and the radiative lifetime is also reported.
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http://dx.doi.org/10.1039/c3dt50438gDOI Listing
June 2013

Evaluating employee health risks due to hypertension and obesity: self-testing workplace health stations.

Authors:
John T Kelly

Postgrad Med 2009 Jan;121(1):152-8

Chief Medical Officer, Lifeclinic International, Inc., Burtonsville, MD, USA.

Background: We evaluated employee health risks due to hypertension, pre-hypertension, overweight, and obesity through the use of self-testing workplace health stations that measure blood pressure (BP) and weight.

Methods: We analyzed BP and weight data from the first 18 months after the installation of health stations in the offices of a financial services company with approximately 20,000 employees in 13 US workplace locations.

Results: Data showed that 21.7% of the employees voluntarily used a health station at least once to measure BP or weight during the first 18 months. Health station usage ranged from a high of 51.8% to a low of 5.3% at the 13 workplace locations. Among health station users, 52.5% used a health station more than once. Health station users used the health stations an average of 4.2 times (median, 2 times). Among health station users, 95.6% measured BP, 92.2% measured weight, and 87.8% measured both BP and weight. Initial BP results were: hypertension 26.7%, prehypertension 40.3%, and normal BP 32.9%. The initial body mass index (BMI) results were: obese 38%, overweight 34.7%, normal weight 25.3%, and underweight 2%. Employees with hypertension on the initial reading used the health stations more frequently than employees with pre-hypertension or normal BP. Employees with an obese BMI result on the initial reading used the health stations more frequently than employees with an overweight or normal BMI result. Many employees reduced their health risks due to hypertension, pre-hypertension, overweight, or obesity, although the health risks of many other employees were unchanged or increased.

Conclusions: Self-testing workplace health stations that measure BP and weight provide employees with information about their health risks due to hypertension, pre-hypertension, overweight, and obesity. Self-testing workplace health stations can also be used to identify at-risk employees who may benefit from health and wellness programs.
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http://dx.doi.org/10.3810/pgm.2009.01.1964DOI Listing
January 2009

Host immune responses to rhinovirus: mechanisms in asthma.

J Allergy Clin Immunol 2008 Oct;122(4):671-682

Section of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wis. Electronic address:

Viral respiratory infections can have a profound effect on many aspects of asthma including its inception, exacerbations, and, possibly, severity. Of the many viral respiratory infections that influence asthma, the common cold virus, rhinovirus, has emerged as the most frequent illness associated with exacerbations and other aspects of asthma. The mechanisms by which rhinovirus influences asthma are not fully established, but current evidence indicates that the immune response to this virus is critical in this process. Many airway cell types are involved in the immune response to rhinovirus, but most important are respiratory epithelial cells and possibly macrophages. Infection of epithelial cells generates a variety of proinflammatory mediators to attract inflammatory cells to the airway with a subsequent worsening of underlying disease. Furthermore, there is evidence that the epithelial airway antiviral response to rhinovirus may be defective in asthma. Therefore, understanding the immune response to rhinovirus is a key step in defining mechanisms of asthma, exacerbations, and, perhaps most importantly, improved treatment.
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http://dx.doi.org/10.1016/j.jaci.2008.08.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3927944PMC
October 2008

The production of communication signals at the air-water and water-substrate boundaries.

J Comp Psychol 2002 Jun;116(2):145-50

Center for Animal Behavior and Section of Neurobiology, Physiology, and Behavior, University of California, Davis, USA.

The 2 interfaces of the aquatic environment, the boundary between air-water and water-substrate, have distinctive physical characteristics that facilitate the production of communication signals. Recent evidence suggests that animals living on or near these boundaries use the interface to generate signals in 2 ways: (a) by producing a signal that propagates along the interface or (b) by producing a signal at the interface that is transmitted and detected within 1 of the component media. By examining the diversity of behaviors used to produce signals at these boundaries, the authors illustrate how human perception of these environments may cause researchers to incorrectly assume the environmental context of signal-generating behaviors and overlook modalities of communication pertinent to the animal.
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http://dx.doi.org/10.1037/0735-7036.116.2.145DOI Listing
June 2002