Atmospheric pressure ionization and liquid chromatography/mass spectrometry—together at last

The evolution of atmospheric pressure ionization techniques which are now routinely applied as liquid chromatograph/mass spectrometer (LC/MS) interfaces is described. Electrospray and related methods, as well as atmospheric pressure chemical ionization combined with the heated nebulizer interface, both began as specialized ionization techniques which became much more widely accepted when combined with tandem mass spectrometry. Today, both are widely used for quantitative and qualitative LC/MS and LC/MS/MS analyses. Important events in the development of these methods are described, along with key elements in the evolution of the ion source-to-vacuum interface techniques that contributed to their success

CLIMATE CHANGE IMPACTS ON US AGRICULTURE

There is general consensus in the scientific literature that human-induced climate change has taken place and will continue to do so over the next century. The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change concludes with “very high confidence” that anthropogenic activities such as fossil fuel burning and deforestation have affected the global climate. The AR4 also indicates that global average temperatures are expected to increase by another 1.1°C to 5.4°C by 2100, depending on the increase in atmospheric concentrations of greenhouse gases that takes place during this time. Increasing atmospheric carbon dioxide levels, temperature increases, altered precipitation patterns and other factors influenced by climate have already begun to impact U.S. agriculture. Climate change will continue to have significant effects on U.S. agriculture, water resources, land resources, and biodiversity in the future as temperature extremes begin exceeding thresholds that harm crop growth more frequently and precipitation and runoff patterns continue to change. In this study, we provide an assessment of the potential long-term implications of climate change on landowner decisions regarding land use, crop mix, and production practices in the U.S., combining a crop process model (Environmental Policy Integrated Climate model) and an economic model of the U.S. forestry and agricultural sector (Forest and Agricultural Sector Optimization Model). Agricultural producers have always faced numerous production and price risks, but forecasts of more rapid changes in climatic conditions in the future have raised concerns that these risks will increase in the future relative to historical conditions.climate change, crop yields, EPIC, FASOM, Crop Production/Industries, Environmental Economics and Policy, International Relations/Trade, Land Economics/Use, Resource /Energy Economics and Policy, C61, Q18, Q54,

Tandem Mobility Mass Spectrometry Study of Electrosprayed Tetraheptyl Ammonium Bromide Clusters

Multiply charged electrospray ions from concentrated solutions of Heptyl4N+Br− (designated A+B− hereafter) in formamide are analyzed mass spectrometrically (MS) following mobility selection in ambient air in a differential mobility analyzer (DMA). Most of the sharp mobility peaks seen are identified as (AB)nA+ clusters, with 0 ≤ n ≤ 5. One anomalously abundant and mobile ion is identified as NH4+(AB)4. Six ions in the (AB)n(A+)2 series are also identified, completing and correcting earlier mobility data for singly and doubly charged ions up to masses of almost 9000 Da. The more mobile of two broad humps seen in the mobility spectrum includes m/z values approximately from 2500 up to 12,000 Da. It is formed primarily by multiply charged (AB)n(A+)z clusters with multiple ammonium bromide adducts. Because of overlapping of many peaks of different m/z and charge state z, only a few individual species can be identified by MS alone in this highly congested region. However, the spectral simplification brought about by mobility selection upstream of the MS reveals a series of broad modulations in m/z space, with all ions resolved in the second, third, …sixth modulation being in charge states z = 2, 3, …6, respectively. Extrapolation of this trend beyond the sixth wave fixes the ion charge state (in some cases up to z = 15) and mass (beyond m = 175,000 u). This wavy structure had been previously observed and explained in terms of ion evaporation kinetics from volatile drops, though without mass identification. All observations indicate that the clusters are formed as charged residues, but their charge state is fixed by the Iribarne-Thomson ion evaporation mechanism. Consequently, the measured curve of cluster diameter versus z yields the two parameters governing ion evaporation kinetics. Clusters with z > 1 and electrical mobility Z > 0.495 cm2/V/s are metastable and evaporate a singly charged cluster, probably (AB)2A+, between the DMA and the MS. Plotting the electrical mobilities Z of the clusters in the form (z/Z)1/2 versus m1/3 (both proportional to cluster diameter) collapse the data for all cluster sizes and charge states into one single straight line for Z below 0.495 cm2/V/s. This linear relation reveals a uniform apparent cluster density of 0.935 g/cm3 and an effective hard-sphere diameter of the air molecules of 0.44 nm. An anomalous mobility increase is observed at diameters below 3 nm

Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids : Implications for understanding soil carbon cycling

Acknowledgments We thank Agnes Fastnacht, Karl Kuebler, Steffen Ruehlow, Iris Kuhlmann, Heike Geilmann, Petra Linke, and Willi Brand for technical support in establishing the experimental setup and/or with stable isotope analyses. We also thank Bernhard Ahrens and Daniel Read for helpful discussions. This project was funded by the Max-Planck-Gesellschaft. We acknowledge Deutsche Forschungsgemeinschaft (DFG) for the fellowship to AAM in the research training group 1257 ‘Alteration and element mobility at microbe-mineral interface’ that is part of the Jena School for Microbial Communication (JSMC). AAM was also supported by the International Max Planck Research School for Global Biogeochemical Cycles (IMPRS-gBGC).Peer reviewedPublisher PD

Bacterial physiological adaptations to contrasting edaphic conditions identified using landscape scale metagenomics

This project was funded by the UK Natural Environment Research Council (standard grant NE/E006353/1 to R.I.G., A.S.W., and M.B. and Soil Security grant NE/M017125/1 to R.I.G.). A.A.M. has received funding from the European Union’s Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie grant no. 655240. We wish to further acknowledge the lab assistance of Phillip James and the staff at the NERC Biomolecular Analysis Facility, University of Liverpool, United Kingdom.Peer reviewedPublisher PD

Environmental Exposure Conditions for Teflon FEP on the Hubble Space Telescope Investigated

The Hubble Space Telescope (HST) was launched into low Earth orbit on April 24,1990. During the first servicing mission in December 1993 (3.6 years after launch), multilayer insulation (MLI) blankets were retrieved from the two magnetic sensing systems located on the light shield. Retrieval of one of the solar arrays during this mission also provided MLI blanket material from the solar array drive arm. These MLI materials were analyzed in ground-based facilities, and results indicate that the space-facing outer layer of the MLI, aluminized Teflon FEP (DuPont; fluorinated ethylene propylene), was beginning to degrade. Close inspection of the FEP revealed through-the-thickness cracks in areas with the highest solar exposure and stress concentration. During the second servicing mission in February 1997 (6.8 years after launch), astronauts observed and documented severe cracking in the outer layer of the MLI blankets on both the solar-facing and anti-solar-facing surfaces. During this second mission, some material from the outer layer of the light shield MLI was retrieved and subsequently analyzed in ground-based facilities. After the second servicing mission, a Failure Review Board was convened by NASA Goddard Space Flight Center to address the MLI degradation problem on HST. Members of the Electro-Physics Branch of the NASA Glenn Research Center at Lewis Field participated on this board. To determine possible degradation mechanisms, board researchers needed to consider all environmental constituents to which the FEP MLI surfaces were exposed. On the basis of measurements, models, and predictions, environmental exposure conditions for FEP surfaces on HST were estimated for various time periods from launch in 1990 through 2010, the planned end-of-life for HST. The table summarizes these data including the number and temperature ranges of thermal cycles; equivalent Sun hours; fluence and absorbed radiation dose from solar event x rays; fluence and absorbed dose from solar wind protons and electrons trapped in Earth s magnetic field; fluence of plasma electrons and protons; and atomic oxygen fluence

Age-dependent elastin degradation is enhanced in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is primarily a lung condition characterised by the presence of persistent airflow limitation resulting from inflammation, remodelling of small airways, and emphysema. It is well-recognised that the impacts of COPD extend beyond the lung with many patients suffering systemic manifestations such as cardiovascular diseases that affect morbidity and mortality [1]. “Accelerated ageing” has been proposed as a mechanism that underlies many of the pulmonary and extrapulmonary consequences of COPD [2, 3]. It is thought that a decline in organ function is a feature of ageing in response to the accumulation of cell and molecular damage, and in the case of COPD, noxious inhalants such as tobacco smoke increase this damage, thus accelerating the ageing process, leading to the development of COPD. With the exception of lung function decline, however, evidence indicating that tobacco smoking or COPD accelerates age-associated deterioration remains scarce

Detecting a stochastic background of gravitational radiation: Signal processing strategies and sensitivities

We analyze the signal processing required for the optimal detection of a stochastic background of gravitational radiation using laser interferometric detectors. Starting with basic assumptions about the statistical properties of a stochastic gravity-wave background, we derive expressions for the optimal filter function and signal-to-noise ratio for the cross-correlation of the outputs of two gravity-wave detectors. Sensitivity levels required for detection are then calculated. Issues related to: (i) calculating the signal-to-noise ratio for arbitrarily large stochastic backgrounds, (ii) performing the data analysis in the presence of nonstationary detector noise, (iii) combining data from multiple detector pairs to increase the sensitivity of a stochastic background search, (iv) correlating the outputs of 4 or more detectors, and (v) allowing for the possibility of correlated noise in the outputs of two detectors are discussed. We briefly describe a computer simulation which mimics the generation and detection of a simulated stochastic gravity-wave signal in the presence of simulated detector noise. Numerous graphs and tables of numerical data for the five major interferometers (LIGO-WA, LIGO-LA, VIRGO, GEO-600, and TAMA-300) are also given. The treatment given in this paper should be accessible to both theorists involved in data analysis and experimentalists involved in detector design and data acquisition.Comment: 81 pages, 30 postscript figures, REVTE

Advances in the Development of Mid-Infrared Integrated Devices for Interferometric Arrays

This article reports the advances on the development of mid-infrared integrated optics for stellar interferometry. The devices are fabricated by laser writing techniques on chalcogenide glasses. Laboratory characterizaton is reported and analyzed.Comment: 12 pages, 9 figures, SPIE Astronomical Telescopes and Instrumentatio