Phosphopeptide/phosphoprotein mapping by electron capture dissociation mass spectrometry

Of methods for dissociation of multiply charged peptide and protein ions, electron capture dissociation (ECD) has the advantages of cleaving between a high proportion of amino acids, without loss of such posttranslational modifications as glycosylation and carboxylation. Here this capability is successfully extended to phosphorylation, for which collisionally activated dissociation (CAD) can cause extensive loss of H3PO4 and HPO3. As shown here, these losses are minimal in ECD spectra, an advantage for measuring the degree of phosphorylation. For phosphorylated peptides, ECD and CAD spectra give complementary backbone cleavages for identifying modification sites. For a 24-kDa heterogeneous phosphoprotein, bovine beta-casein, activated ion ECD cleaved 87 of 208 backbone bonds that identified a phosphorylation site at Ser-15, and localized three more among Ser-17,-18, -19, and -22 and Thr-24, and the last among four other sites. This is the first direct site-specific characterization of this key post-translational modification on a protein without its prior degradation, such as proteolysis.     

Application of Balanced Detection to Absorption Measurements of Trace Gases with Room-Temperature, Quasi-cw Quantum-Cascade Lasers

Distributed-feedback quantum-cascade (QC) lasers are expected to form the heart of the next-generation mid-IR laser absorption spectrometers, especially as they are applied to measurements of trace gases in a variety of environments. The incorporation of room-temperature-operable, single-mode QC lasers should result in highly compact and rugged sensors for real-world applications. We report preliminary results on the performance of a laser absorption spectrometer that uses a QC laser operating at room temperature in a quasi-cw mode in conjunction with balanced ratiometric detection. We have demonstrated sensitivities for N(2)O [10 parts in 10(6) volume-mixing ratio for a 1-m path (ppmv-m)] and NO [520 parts in 10(9) volume-mixing ratio for a 1-m path (ppbv-m)] at 5.4 mum. System improvements are described that are expected to result in a 2 orders of magnitude increase in sensitivity.     

Natural radionuclides contents and radon exhalation rates in building materials used in South Korea

The natural radionuclide (226Ra, 232Th and 40K) contents of building materials commonly used in South Korea have been determined by a gamma ray spectroscopy system using a high purity germanium detector. The radon exhalation rates and emanation coefficients of building materials have also been studied. The average concentrations of 226Ra, 232Th and 40K in building materials were in the range of 6.47-271 Bq.kg-1, N.D.-89.9 Bq.kg-1 and 16.8-1081 Bq.kg-1, respectively. The average radon exhalation rates and emanation coefficients were in the range of 0.0061-0.2404 Bq.kg-1.h-1 and 2.39-11.5%, respectively.     

Mitigation of dense gas releases within buildings: validation of CFD modelling

When an accidental release of a hazardous material is considered within a safety case or risk assessment, its off-site effects are generally assessed by calculating the dispersion of vapour from the site. Although most installations handling flammable materials will be in the open air, many types of plant, particularly those handling toxics, are enclosed, partly to provide some form of containment and hence, to mitigate the effects of any release. When such a release occurs within a building, the gas or vapour will undergo some mixing before emerging from any opening. The degree of mixing will depend upon the building geometry and the nature of the ventilation, which in turn may be modified by the leak. This situation is considered in this paper, with specific application to calculating the rate of release of a dense vapour from a building. The paper describes the application of computational fluid dynamics (CFD) techniques to modelling the release and mixing processes within buildings. Examples of validation calculations for simple geometric arrangements, as well as more complex geometries representative of an industrial site, are described. The results demonstrate the capabilities of CFD for this application but highlight the need for careful modelling of the near-wall flows and heat transfer, and need for an accurate fluid dynamics and thermodynamic representation of the release source.     

Perceptual processes used by drivers during overtaking in a driving simulator

This study investigated the control strategies and decision making of drivers who were executing overtaking maneuvers in a fixed-base driving simulator. It was found that drivers were frequently inaccurate in deciding whether it was safe to overtake in front of an oncoming vehicle. One source of error in this situation was the control strategy adopted by the driver; in several instances our drivers initiated an overtaking maneuver when the oncoming car's distance was above a critical value, even though there was not sufficient time to complete a safe maneuver. Adaptation to closing speed (produced by driving on a straight open road) also had large effects on overtaking behavior. For all participants, closing speed adaptation resulted in decisions that were delayed, of higher risk, and more variable. Actual or potential applications of this research include improved training for younger drivers and the development of in-car interfaces that reduce closing speed adaptation.     

Multi-layered PZT/polymer composites to increase signal-to-noise ratio and resolution for medical ultrasound transducers part II: thick film technology

For pt.I, see ibid., vol.46, no.4, p.961-71 (1999). Increasing transducer bandwidth and signal-to-noise ratio (SNR) is fundamental to improving the quality of medical ultrasound images. In previous work, we have proposed the use of multi-layer 1-3 PZT/polymer composites to increase both, but have encountered significant fabrication challenges. Thus, we have developed a multi-layer composite hybrid array that will not require post alignment. Starting from a 2-MHz, three-layer PZT-5H, thick film transducer designed for 1.5-D arrays, cuts are made only through the top layer and back-filled with epoxy, forming a composite layer on top of two ceramic layers. Finite element (PZFlex) simulations show that for a 2-MHz phased-array element with a single matching layer, the three-layer hybrid structure increases the pulse echo SNR by 11 dB versus a single layer PZT element and improves -6 dB pulse echo fractional bandwidth by a factor of 1.4. Composite hybrid arrays fabricated in our laboratory showed an improvement in SNR of 6 to 11 dB over a PZT control and an increase in -6 dB bandwidth by a factor of 1.1. Images from a phased-array scanner confirmed these improvements     

(11<Emphasis Type="Italic">Z</Emphasis>,13<Emphasis Type="Italic">E</Emphasis>)-Hexadecadien-1-yl Acetate: Sex Pheromone of the Grass Webworm <Emphasis Type="Italic">Herpetogramma licarsisalis</Emphasis>—Identification,Synthesis, and Field Bioassays

The grass webworm Herpetogramma licarsisalis (Lepidoptera: Crambidae), which has recently established in pasture in Northland, New Zealand, is an important pest of many tropical and subtropical grasses. Two pheromone components, (Z)-11-hexadecen-1-yl acetate (Z11–16:Ac) and (11Z,13E)-hexadecadien-1-yl acetate (Z11,E13–16:Ac), were identified in pheromone gland extracts of female moths by gas chromatography (GC), GC-electroantennographic detection, and GC-mass spectrometry in conjunction with microchemical tests (dimethyldisulfide and 4-methyl-1,2,4-triazoline-3,5-dione derivatizations). Z11,E13–16:Ac and its geometric isomer (11E,13Z)-hexadecadien-1-yl acetate (E11,Z13–16:Ac) were synthesized via stereoselective Wittig reactions, and the identity of the diene present in the pheromone glands was confirmed to be Z11,E13–16:Ac. Field bioassays at Indooroopilly in Brisbane, Australia, established that Z11,E13–16:Ac was necessary and sufficient for attraction of male grass webworm moths and that the corresponding alcohol, (11Z,13E)-hexadecadien-1-ol (Z11,E13–16:OH), had a strong inhibitory effect on trap catches at the ratios tested. When mixed with Z11,E13–16:Ac in various ratios, Z11–16:Ac had no effect on the attractiveness of lures. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.