Operation of low-noise single-gap RPC modules exposed to ionisation rates up to 1 kHz /cm2

NASA Astrophysics Data System (ADS)

Ćwiok, M.; Dominik, W.; Górski, M.; Królikowski, J.

2004-11-01

Two single gap medium-size RPC modules, made of bakelite plates of very good mechanical quality of the surface and having initial volume resistivity of 1 ×1010 Ω cm, were tested in the Gamma Irradiation Facility at CERN at ionisation rates up to 1 kHz /cm2. The internal surfaces facing the gas volume of one RPC module were cladded with a thin layer of linseed oil varnish for comparison of oiled and non-oiled RPC operation. The results refer to the gas mixture of C2H2F4/isobutane (97:3) with SF6 addition below 1%. The single gap modules exhibited full detection efficiency plateau for the high voltage range of about 1 kV at full intensity of gamma rays. Good timing characteristics allowed to reach 95% efficiency at fully opened irradiation source with time window of 20 ns. The intrinsic noise rate for a non-oiled and an oiled RPC gap was, respectively, below 5 and 1 Hz /cm2 at full efficiency over 1 kV voltage range.

Metabolite signal identification in accurate mass metabolomics data with MZedDB, an interactive m/z annotation tool utilising predicted ionisation behaviour 'rules'

PubMed Central

Draper, John; Enot, David P; Parker, David; Beckmann, Manfred; Snowdon, Stuart; Lin, Wanchang; Zubair, Hassan

2009-01-01

Background Metabolomics experiments using Mass Spectrometry (MS) technology measure the mass to charge ratio (m/z) and intensity of ionised molecules in crude extracts of complex biological samples to generate high dimensional metabolite 'fingerprint' or metabolite 'profile' data. High resolution MS instruments perform routinely with a mass accuracy of < 5 ppm (parts per million) thus providing potentially a direct method for signal putative annotation using databases containing metabolite mass information. Most database interfaces support only simple queries with the default assumption that molecules either gain or lose a single proton when ionised. In reality the annotation process is confounded by the fact that many ionisation products will be not only molecular isotopes but also salt/solvent adducts and neutral loss fragments of original metabolites. This report describes an annotation strategy that will allow searching based on all potential ionisation products predicted to form during electrospray ionisation (ESI). Results Metabolite 'structures' harvested from publicly accessible databases were converted into a common format to generate a comprehensive archive in MZedDB. 'Rules' were derived from chemical information that allowed MZedDB to generate a list of adducts and neutral loss fragments putatively able to form for each structure and calculate, on the fly, the exact molecular weight of every potential ionisation product to provide targets for annotation searches based on accurate mass. We demonstrate that data matrices representing populations of ionisation products generated from different biological matrices contain a large proportion (sometimes > 50%) of molecular isotopes, salt adducts and neutral loss fragments. Correlation analysis of ESI-MS data features confirmed the predicted relationships of m/z signals. An integrated isotope enumerator in MZedDB allowed verification of exact isotopic pattern distributions to corroborate experimental data. Conclusion We conclude that although ultra-high accurate mass instruments provide major insight into the chemical diversity of biological extracts, the facile annotation of a large proportion of signals is not possible by simple, automated query of current databases using computed molecular formulae. Parameterising MZedDB to take into account predicted ionisation behaviour and the biological source of any sample improves greatly both the frequency and accuracy of potential annotation 'hits' in ESI-MS data. PMID:19622150

Pterodon pubescens oil: characterisation, certification of origin and quality control via mass spectrometry fingerprinting analysis.

PubMed

Cabral, E C; Sevart, L; Spindola, H M; Coelho, M B; Sousa, I M O; Queiroz, N C A; Foglio, M A; Eberlin, M N; Riveros, J M

2013-02-01

The oil obtained from Pterodon pubescens (Leguminosae) seeds are known to display anti-cancer, anti-dermatogenic and anti-nociceptive activitiy. Phytochemical studies have demonstrated that its main constituents are diterpenoids with voucapan skeletons. Considering the potential biological activities of the oil, rapid and efficient methods for assessing its quality would facilitate certification and quality control. To develop a direct mass spectrometric fingerprinting method for the P. pubescens seed oil that would focus on the major diterpenoids constituents, enabling quality control, origin certification and recognition of marker species in commercially available products. Two techniques were used: (i) direct infusion electrospray ionisation (ESI) mass spectrometry after solvent extraction and dilution and (ii) ambient desorption/ionisation via easy ambient sonic-spray ionisation, EASI(+)-MS, performed directly on the seed surface or at a paper surface imprinted with the oil. From a combination of ESI-MS, HRESI-MS and ESI-MS/MS data, 12 diterpenes were characterised, and typical profiles were obtained for the oil extract or the crude oil via both ESI-MS and EASI-MS. These techniques require no or very simple sample preparation protocols and the whole analytical processes with spectra acquisition take just a few minutes. Both techniques, but particularly EASI-MS, provide simple, fast and efficient MS fingerprinting methodologies to characterise the P. pubescens oil with typical (di)terpene profiles being applicable to quality control and certification of authenticity and origin. Copyright © 2012 John Wiley & Sons, Ltd.

Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

NASA Astrophysics Data System (ADS)

Zvorykin, V. D.; Ionin, Andrei A.; Levchenko, A. O.; Mesyats, Gennadii A.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, Igor V.; Sunchugasheva, E. S.; Ustinovskii, N. N.; Shutov, A. V.

2013-04-01

The problem of the production of extended (~1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (~100 ns), maintains the electron density at a level ne = (3-5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (~0.5 eV) and a long lifetime (~1 ms), which are produced upon cessation of the laser pulse.

EURADOS strategic research agenda: vision for dosimetry of ionising radiation

PubMed Central

Rühm, W.; Fantuzzi, E.; Harrison, R.; Schuhmacher, H.; Vanhavere, F.; Alves, J.; Bottollier Depois, J. F.; Fattibene, P.; Knežević, Ž.; Lopez, M. A.; Mayer, S.; Miljanić, S.; Neumaier, S.; Olko, P.; Stadtmann, H.; Tanner, R.; Woda, C.

2016-01-01

Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises—based on input from EURADOS Working Groups (WGs) and Voting Members—five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org). PMID:25752758

Improved communication, understanding of risk perception and ethics related to ionising radiation.

PubMed

Perko, Tanja; Raskob, Wolfgang; Jourdain, Jean-Rene

2016-06-06

In Europe today, institutions, media and the general public exchange information about ionizing radiation and associated risks. However, communication about ionising radiation with the general public has to be further improved, as has been previously highlighted by international responses to the 2011 accident in Japan. This article reports the main activities and findings in this field from the following three FP7 projects: EAGLE, PREPARE and OPERRA and discussed by a broad spectrum of stakeholders at the conference RICOMET 2015. These projects, among other aims, also investigate how communication about ionising radiation in different fields could be improved and harmonised, how radiological risks are perceived, how to encourage ethical considerations in all fields of nuclear applications and what kind of transdisciplinary research is needed. The projects relate to several domains; the first relates to education, training and communication, the second to nuclear emergency preparedness and response, and the third to research and development in the radiation protection field. Incorporation of stakeholder engagement activities such as the RICOMET conference broadens social and ethical aspects and takes them into account during coordination activities as well as during core scientific and nuclear research and development performed in the projects. These activities offered opportunities for moving closer to a citizen-centred ideal of risk communication in particular and nuclear research and development in general.

RF System for the MICE Demonstration of Ionisation Cooling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ronald, K.; et al.

2017-04-01

Muon accelerators offer an attractive option for a range of future particle physics experiments. They can enable high energy (TeV+) high energy lepton colliders whilst mitigating the difficulty of synchrotron losses, and can provide intense beams of neutrinos for fundamental physics experiments investigating the physics of flavor. The method of production of muon beams results in high beam emittance which must be reduced for efficient acceleration. Conventional emittance control schemes take too long, given the very short (2.2 microsecond) rest lifetime of the muon. Ionisation cooling offers a much faster approach to reducing particle emittance, and the international MICE collaborationmore » aims to demonstrate this technique for the first time. This paper will present the MICE RF system and its role in the context of the overall experiment.« less

Determination of acrylamide in coffee and chocolate by pressurised fluid extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Pardo, O; Yusà, V; Coscollà, C; León, N; Pastor, A

2007-07-01

A selective and sensitive procedure has been developed and validated for the determination of acrylamide in difficult matrices, such as coffee and chocolate. The proposed method includes pressurised fluid extraction (PFE) with acetonitrile, florisil clean-up purification inside the PFE extraction cell and detection by liquid chromatography (LC) coupled to atmospheric pressure ionisation in positive mode tandem mass spectrometry (APCI-MS-MS). Comparison of ionisation sources (atmospheric pressure chemical ionisation (APCI), atmospheric pressure photoionization (APPI) and the combined APCI/APPI) and clean-up procedures were carried out to improve the analytical signal. The main parameters affecting the performance of the different ionisation sources were previously optimised using statistical design of experiments (DOE). PFE parameters were also optimised by DOE. For quantitation, an isotope dilution approach was used. The limit of quantification (LOQ) of the method was 1 microg kg(-1) for coffee and 0.6 microg kg(-1) for chocolate. Recoveries ranged between 81-105% in coffee and 87-102% in chocolate. The accuracy was evaluated using a coffee reference test material FAPAS T3008. Using the optimised method, 20 coffee and 15 chocolate samples collected from Valencian (Spain) supermarkets, were investigated for acrylamide, yielding median levels of 146 microg kg(-1) in coffee and 102 microg kg(-1) in chocolate.

Ionisation Feedback in Star and Cluster Formation Simulations

NASA Astrophysics Data System (ADS)

Ercolano, Barbara; Gritschneder, Matthias

2011-04-01

Feedback from photoionisation may dominate on parsec scales in massive star-forming regions. Such feedback may inhibit or enhance the star formation efficiency and sustain or even drive turbulence in the parent molecular cloud. Photoionisation feedback may also provide a mechanism for the rapid expulsion of gas from young clusters' potentials, often invoked as the main cause of `infant mortality'. There is currently no agreement, however, with regards to the efficiency of this process and how environment may affect the direction (positive or negative) in which it proceeds. The study of the photoionisation process as part of hydrodynamical simulations is key to understanding these issues, however, due to the computational demand of the problem, crude approximations for the radiation transfer are often employed. We will briefly review some of the most commonly used approximations and discuss their major drawbacks. We will then present the results of detailed tests carried out using the detailed photoionisation code mocassin and the SPH+ionisation code iVINE code, aimed at understanding the error introduced by the simplified photoionisation algorithms. This is particularly relevant as a number of new codes have recently been developed along those lines. We will finally propose a new approach that should allow to efficiently and self-consistently treat the photoionisation problem for complex radiation and density fields.

[Statistical process control applied to intensity modulated radiotherapy pretreatment controls with portal dosimetry].

PubMed

Villani, N; Gérard, K; Marchesi, V; Huger, S; François, P; Noël, A

2010-06-01

The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (IMRT) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. At Alexis-Vautrin center, pretreatment quality controls in IMRT for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multileaf collimator). Correlation between dose measured at one point, given with the EPID and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. The study allowed to demonstrate the feasibility to reduce the time devoted to pretreatment controls, by substituting the ionisation chamber's measurements with those performed with EPID, and also that a statistical process control monitoring of data brought security guarantee. 2010 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Thermally annealed gold nanoparticles for surface-assisted laser desorption ionisation-mass spectrometry of low molecular weight analytes.

PubMed

Pilolli, Rosa; Ditaranto, Nicoletta; Di Franco, Cinzia; Palmisano, Francesco; Cioffi, Nicola

2012-10-01

Metal nanomaterials have an emerging role in surface-assisted laser desorption ionisation-mass spectrometry (SALDI-MS) providing a useful tool to overcome some limitations intrinsically related to the use of conventional organic matrices in matrix-assisted LDI-MS. In this contribution, the possibility to use a stainless-steel-supported gold nanoparticle (AuNP) film as a versatile platform for SALDI-MS was assessed. A sacrificial anode electrosynthetic route was chosen in order to obtain morphologically controlled core-shell AuNPs; the colloidal AuNPs were, thereafter, drop cast onto a stainless-steel sample plate and the resulting AuNP film was thermally annealed in order to improve its effectiveness as LDI-MS promoter. Spectroscopic characterization of the nanostructured film by X-ray photoelectron spectroscopy was crucial for understanding how annealing induced changes in the surface chemistry and influenced the performance of AuNPs as desorption/ionisation promoter. In particular, it was demonstrated that the post-deposition treatments were essential to enhance the AuNP core/analyte interaction, thus resulting in SALDI-MS spectra of significantly improved quality. The AuNP films were applied to the detection of three different classes of low molecular weight (LMW) analytes, i.e. amino acids, peptides and LMW polymers, in order to demonstrate the versatility of this nanostructured material.

A Discussion about Ionising and Non-Ionising Radiation and the Critical Issue of Mobile Phones

ERIC Educational Resources Information Center

Kontomaris, Stylianos-Vasileios; Malamou, Anna

2018-01-01

Electromagnetic radiation is one of the most important issues affecting peoples' lives today. The misunderstanding of students and the general population of the effects of electromagnetic radiation is a problem which must be eliminated. Thus, a discussion about ionising and non-ionising radiation focusing on the crucial issue of radiation emitted…

Cooking strongly coupled plasmas

NASA Astrophysics Data System (ADS)

Clérouin, Jean

2015-09-01

We present the orbital-free method for dense plasmas which allows for efficient variable ionisation molecular dynamics. This approach is a literal application of density functional theory where the use of orbitals is bypassed by a semi-classical estimation of the electron kinetic energy through the Thomas-Fermi theory. Thanks to a coherent definition of ionisation, we evidence a particular regime in which the static structure no longer depends on the temperature: the Γ-plateau. With the help of the well-known Thomas-Fermi scaling laws, we derive the conditions required to obtain a plasma at a given value of the coupling parameter and deduce useful fits. Static and dynamical properties are predicted as well as a a simple equation of state valid on the Γ-plateau. We show that the one component plasma model can be helpful to describe the correlations in real systems.

Ionising sources in the coma of 67P probed by Rosetta

NASA Astrophysics Data System (ADS)

Heritier, Kevin; Galand, Marina; Henri, Pierre; Eriksson, Anders; Odelstad, Elias; Altwegg, Kathrin; Beth, Arnaud; Broiles, Thomas; Burch, Jim; Carr, Christopher; Cupido, Emanuele; Glassmeier, Karl-Heinz; Nilsson, Hans; Richter, Ingo; Rubin, Martin; Vallieres, Xavier; Vigren, Erik

2017-04-01

An ionospheric model has been developed in order to quantify the ion number density in the coma of 67P/Churyumov-Gerasimenko. The model is driven by Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Cometary Pressure Sensor (COPS) neutral density and assumes isentropic expansion for the neutral density profile. The two ionisation sources considered are photo-ionisation by solar extreme ultraviolet (EUV) radiation and electron-impact ionisation. The EUV radiation is estimated from fluxes measured by the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED)/ Solar EUV Experiment (SEE), taking into account the phase shift and the heliocentric distance ratio; between Earth and comet 67P. The electron-impact ionisation production rates are derived from Rosetta Plasma Consortium (RPC)-Ion and Electron Sensor (IES) integrated electron fluxes and corrected for the S/C potential from RPC/LAngmuir Probe (LAP) measurements. Our results are compared with in situ measurements of the plasma density from RPC-Mutual Impedance Probe (MIP) and RPC-LAP. There is a good agreement between the modelled and RPC observed electron densities. The ionospheric model enables to distinguish the relative contributions of the different sources to the total cometary plasma. At high heliocentric distances, electron-impact ionisation becomes the dominant ionisation source and is enhanced over the winter hemisphere. As the solar activity has decreased since the beginning of the mission in 2014, the relative importance of photo-ionisation has decreased as well. However, at low heliocentric distances, photo-ionisation seems to be the most dominant ionising source, in particular through the perihelion period in summer 2015.

A discussion about ionising and non-ionising radiation and the critical issue of mobile phones

NASA Astrophysics Data System (ADS)

Kontomaris, Stylianos-Vasileios; Malamou, Anna

2018-01-01

Electromagnetic radiation is one of the most important issues affecting peoples’ lives today. The misunderstanding of students and the general population of the effects of electromagnetic radiation is a problem which must be eliminated. Thus, a discussion about ionising and non-ionising radiation focusing on the crucial issue of radiation emitted by mobile phones is presented.

Electron Impact Ionization Cross Sections in Rb and Cs.

NASA Astrophysics Data System (ADS)

Reddish, T. J.; Lukomski, M.; Sutton, S.; Kedzierski, W.; McConkey, J. W.; Bartschat, K.; Bartlett, P. L.; Stelbovics, A. T.; Bray, I.

2006-05-01

We present a new atom trapping technique for determining absolute, total ionisation cross sections (TICS) out of an excited atom. The novel feature of this method is in utilizing Doppler cooling of neutral atoms to determine ionisation cross sections. This fluorescence-monitoring experiment, which is a variant of the `trap loss' technique, has enabled us to obtain the experimental electron impact ionisation cross sections out of the Cs 6^2P3/2 excited state between 7 - 400 eV. New CCC, R-Matrix with Pseudo-States (RMPS), and Born approximation single ionisation cross sections (SICS) are also presented for both the ground and excited states of Cs and Rb, and compared with the available experimental data. The comparison of the results reveals the importance of the autoionisation and multiple ionisation contributions to the TICS. The autoionisation contribution appears to be substantial for ionisation out of the Cs 6^2P and Rb 5^2P excited states; ˜ 3-4 larger than the direct ionisation contribution predicted by CCC at ˜ 30-50 eV. This surprising result shows the importance of multi-electron processes in determining the ionisation cross sections of heavy alkali atoms.

Direct identification of bacteria in positive blood culture bottles by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry.

PubMed

La Scola, Bernard; Raoult, Didier

2009-11-25

With long delays observed between sampling and availability of results, the usefulness of blood cultures in the context of emergency infectious diseases has recently been questioned. Among methods that allow quicker bacterial identification from growing colonies, matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry was demonstrated to accurately identify bacteria routinely isolated in a clinical biology laboratory. In order to speed up the identification process, in the present work we attempted bacterial identification directly from blood culture bottles detected positive by the automate. We prospectively analysed routine MALDI-TOF identification of bacteria detected in blood culture by two different protocols involving successive centrifugations and then lysis by trifluoroacetic acid or formic acid. Of the 562 blood culture broths detected as positive by the automate and containing one bacterial species, 370 (66%) were correctly identified. Changing the protocol from trifluoroacetic acid to formic acid improved identification of Staphylococci, and overall correct identification increased from 59% to 76%. Lack of identification was observed mostly with viridans streptococci, and only one false positive was observed. In the 22 positive blood culture broths that contained two or more different species, only one of the species was identified in 18 samples, no species were identified in two samples and false species identifications were obtained in two cases. The positive predictive value of bacterial identification using this procedure was 99.2%. MALDI-TOF MS is an efficient method for direct routine identification of bacterial isolates in blood culture, with the exception of polymicrobial samples and viridans streptococci. It may replace routine identification performed on colonies, provided improvement for the specificity of blood culture broths growing viridans streptococci is obtained in the near future.

How do air ions reflect variations in ionising radiation in the lower atmosphere in a boreal forest?

NASA Astrophysics Data System (ADS)

Chen, Xuemeng; Kerminen, Veli-Matti; Paatero, Jussi; Paasonen, Pauli; Manninen, Hanna E.; Nieminen, Tuomo; Petäjä, Tuukka; Kulmala, Markku

2016-11-01

Most of the ion production in the atmosphere is attributed to ionising radiation. In the lower atmosphere, ionising radiation consists mainly of the decay emissions of radon and its progeny, gamma radiation of the terrestrial origin as well as photons and elementary particles of cosmic radiation. These types of radiation produce ion pairs via the ionisation of nitrogen and oxygen as well as trace species in the atmosphere, the rate of which is defined as the ionising capacity. Larger air ions are produced out of the initial charge carriers by processes such as clustering or attachment to pre-existing aerosol particles. This study aimed (1) to identify the key factors responsible for the variability in ionising radiation and in the observed air ion concentrations, (2) to reveal the linkage between them and (3) to provide an in-depth analysis into the effects of ionising radiation on air ion formation, based on measurement data collected during 2003-2006 from a boreal forest site in southern Finland. In general, gamma radiation dominated the ion production in the lower atmosphere. Variations in the ionising capacity came from mixing layer dynamics, soil type and moisture content, meteorological conditions, long-distance transportation, snow cover attenuation and precipitation. Slightly similar diurnal patterns to variations in the ionising capacity were observed in air ion concentrations of the cluster size (0.8-1.7 nm in mobility diameters). However, features observed in the 0.8-1 nm ion concentration were in good connection to variations of the ionising capacity. Further, by carefully constraining perturbing variables, a strong dependency of the cluster ion concentration on the ionising capacity was identified, proving the functionality of ionising radiation in air ion production in the lower atmosphere. This relationship, however, was only clearly observed on new particle formation (NPF) days, possibly indicating that charges after being born underwent different processes on NPF days and non-event days and also that the transformation of newly formed charges to cluster ions occurred in a shorter timescale on NPF days than on non-event days.

Test beam results of micro channel plates in 'ionisation mode' for the detection of single charged particle and electromagnetic showers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnyakov, A.; Barnyakov, M.; Novosibirsk State University, str. Pirogova 2, Novosibirsk,

2015-07-01

IMCP is an R and D project aimed at the exploitation of secondary emission of electrons from the surface of microchannel plates (MCP) for fast timing of showers in high rate environments. The usage of MCPs in 'ionisation' mode has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The fast time resolution of MCPs exceeds anything that has been previously used in calorimeters, and, if exploited effectively, could aid in the event reconstruction at high luminosities. Results from testsmore » with electrons with energies up to 150 GeV of MCP devices with different characteristics will be presented, in particular detection efficiency and time resolution. (authors)« less

The WISSH quasars project. I. Powerful ionised outflows in hyper-luminous quasars

NASA Astrophysics Data System (ADS)

Bischetti, M.; Piconcelli, E.; Vietri, G.; Bongiorno, A.; Fiore, F.; Sani, E.; Marconi, A.; Duras, F.; Zappacosta, L.; Brusa, M.; Comastri, A.; Cresci, G.; Feruglio, C.; Giallongo, E.; La Franca, F.; Mainieri, V.; Mannucci, F.; Martocchia, S.; Ricci, F.; Schneider, R.; Testa, V.; Vignali, C.

2017-02-01

Models and observations suggest that both the power and effects of AGN feedback should be maximised in hyper-luminous (LBol > 1047 erg s-1) quasars, I.e. objects at the brightest end of the AGN luminosity function. In this paper, we present the first results of a multiwavelength observing programme, focusing on a sample of WISE/SDSS selected hyper-luminous (WISSH) broad-line quasars at z ≈ 1.5-5. The WISSH quasars project has been designed to reveal the most energetic AGN-driven outflows, estimate their occurrence at the peak of quasar activity, and extend the study of correlations between outflows and nuclear properties up to poorly investigated, extreme AGN luminosities, I.e. LBol 1047 - 1048 erg s-1. We present near-infrared, long-slit LBT/LUCI1 spectroscopy of five WISSH quasars at z ≈ 2.3 - 3.5, showing prominent [OIII] emission lines with broad (FWHM 1200-2200 km s-1) and skewed profiles. The luminosities of these broad [OIII] wings are the highest measured so far, with L[OIII]broad ≳ 5 × 1044 erg s-1, and reveal the presence of powerful ionised outflows with associated mass outflow rates Ṁ ≳ 1700M⊙ yr-1 and kinetic powers Ėkin ≳ 1045 erg s-1. Although these estimates are affected by large uncertainties because of the use of [OIII] as a tracer of ionised outflows and the very basic outflow model adopted here, these results suggest that in our hyper-luminous targets the AGN is highly efficient at pushing large amounts of ionised gas outwards. Furthermore, the mechanical outflow luminosities measured for WISSH quasars correspond to higher percentages ( 1-3%) of LBol than those derived for AGN with lower LBol. Our targets host very massive (MBH ≳ 2 × 109M⊙) black holes that are still accreting at a high rate (I.e. a factor of 0.4-3 of the Eddington limit). These findings clearly demonstrate that WISSH quasars offer the opportunity to probe the extreme end of both luminosity and supermassive black holes (SMBH) mass functions and revealing powerful ionised outflows that are able to affect the evolution of their host galaxies.

Occupational external exposure to ionising radiation in France (2005-2011).

PubMed

Feuardent, J; Scanff, P; Crescini, D; Rannou, A

2013-12-01

The Institute for Radiological Protection and Nuclear Safety (IRSN) produces the French annual report on occupational exposure to ionising radiation, collecting all national data and aggregating the results according to a unique activity classification expected to be shared by all involved in personal dosimetric monitoring (employers, external dosimetry services and IRSN). Nearly 344,000 monitored workers were counted in France in 2011, with a collective dose of 64.24 man.Sv. The average annual dose (as calculated over the number of measurably exposed workers) differed among the main activity fields: 0.54 mSv in medical and veterinary activities, 1.18 mSv in the nuclear field, 1.60 mSv in non-nuclear industry and 0.47 mSv in research activities. Because of improved knowledge about worker activities, the results for year 2011 are detailed per activity sectors in each field. Lasting limitations prevent from having complete and reliable worker activity information. Solutions are considered to reduce the inaccuracy in the annually published statistics. The evolution of occupational external exposure to ionising radiation from 2005 to 2011 in France is then presented for the main activity fields.

Metabolic profiling using direct infusion electrospray ionisation mass spectrometry for the characterisation of olive oils.

PubMed

Goodacre, Royston; Vaidyanathan, Seetharaman; Bianchi, Giorgio; Kell, Douglas B

2002-11-01

There is a continuing need for improved methods for assessing the adulteration of foodstuffs. We report some highly encouraging data, where we have developed direct infusion electrospray ionisation mass spectrometry (ESI-MS) together with chemometrics as a novel, rapid (1 min per sample) and powerful technique to elucidate key metabolite differences in vegetable and nut oils. Principal components analysis of these ESI-MS spectra show that the reproducibility of this approach is high and that olive oil can be discriminated from oils which are commonly used as adulterants. These adulterants include refined hazelnut oil, which is particularly challenging given its chemical similarity to olive oils.

Capillary electrophoresis with electrospray ionisation-mass spectrometry for the characterisation of degradation products in aged papers.

PubMed

Dupont, Anne-Laurence; Seemann, Agathe; Lavédrine, Bertrand

2012-01-30

A methodology for capillary electrophoresis/electrospray ionisation mass spectrometry (CE/ESI-MS) was developed for the simultaneous analysis of degradation products from paper among two families of compounds: low molar mass aliphatic organic acids, and aromatic (phenolic and furanic) compounds. The work comprises the optimisation of the CE separation and the ESI-MS parameters for improved sensitivity with model compounds using two successive designs of experiments. The method was applied to the analysis of lignocellulosic paper at different stages of accelerated hygrothermal ageing. The compounds of interest were identified. Most of them could be quantified and several additional analytes were separated. Copyright © 2011 Elsevier B.V. All rights reserved.

EURADOS strategic research agenda: vision for dosimetry of ionising radiation.

PubMed

Rühm, W; Fantuzzi, E; Harrison, R; Schuhmacher, H; Vanhavere, F; Alves, J; Bottollier Depois, J F; Fattibene, P; Knežević, Ž; Lopez, M A; Mayer, S; Miljanić, S; Neumaier, S; Olko, P; Stadtmann, H; Tanner, R; Woda, C

2016-02-01

Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises-based on input from EURADOS Working Groups (WGs) and Voting Members-five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org). © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Reliability in individual monitoring service.

PubMed

Mod Ali, N

2011-03-01

As a laboratory certified to ISO 9001:2008 and accredited to ISO/IEC 17025, the Secondary Standard Dosimetry Laboratory (SSDL)-Nuclear Malaysia has incorporated an overall comprehensive system for technical and quality management in promoting a reliable individual monitoring service (IMS). Faster identification and resolution of issues regarding dosemeter preparation and issuing of reports, personnel enhancement, improved customer satisfaction and overall efficiency of laboratory activities are all results of the implementation of an effective quality system. Review of these measures and responses to observed trends provide continuous improvement of the system. By having these mechanisms, reliability of the IMS can be assured in the promotion of safe behaviour at all levels of the workforce utilising ionising radiation facilities. Upgradation of in the reporting program through a web-based e-SSDL marks a major improvement in Nuclear Malaysia's IMS reliability on the whole. The system is a vital step in providing a user friendly and effective occupational exposure evaluation program in the country. It provides a higher level of confidence in the results generated for occupational dose monitoring of the IMS, thus, enhances the status of the radiation protection framework of the country.

Multidisciplinary approach to assess the sensitivity of dwarf tomato plants to low-LET ionising radiation

NASA Astrophysics Data System (ADS)

De Micco, Veronica; De Pascale, Stefania; Aronne, Giovanna; Paradiso, Roberta; Vitaglione, Paola; Turano, Mimmo; Arena, Carmen

Ionising radiation, acting alone or in interaction with microgravity and other environmental constraints, may affect plant at molecular, morpho-structural and physiological level. The intensity of the plant’s response depends on the properties of radiation and on the features of the plant itself. Indeed, different species are characterised by different susceptibility to radiation which may change during the life course. The aim of this research was to study the radiosensitivity to low-LET ionising radiation of plants of dwarf tomato (Solanum lycopersicum L. ‘Microtom’) at two phenological phases (vegetative and reproductive), within the purpose of analysing plants for consideration as candidates for Bioregenerative Life Support Systems (BLSS) in Space. To pursue this objective, plants of the cultivar Microtom were irradiated with different doses of X-rays either at the stage of the second true leaf (VP - vegetative phase) or when at least one flower was blossomed (RP - reproductive phase). Plant’s response to ionising radiation was assessed through a multidisciplinary approach combining genetic analyses, ecophysiological measurements, morpho-anatomical characterisation of leaves and fruits, nutritional analyses of fruits. Growth, molecular and morpho-functional traits were measured during plant development up to fruiting in both VP and RP plant groups, and compared with non-irradiated control plants. Plant growth was monitored weekly recording parameters such as plant height, number of leaves, leaf area, flowering and fruiting rate. Potential DNA alterations were explored through Random Amplified Polymorphic DNA (RAPD) technique. The efficiency of the photosynthetic apparatus was evaluated by determining photosynthetic pigment composition, photochemistry and leaf gas exchanges. Leaf and fruit structure were analysed through light and epi-fluorescence microscopy. Leaf anatomical traits related to photosynthetic efficiency, and to structural radioprotection, were quantified through digital image analysis. Antioxidant content was analysed in fruits, with specific reference to different carotenoids. Results showed that different doses of X-rays determine differential responses depending on the plant phenological phase at the time of exposure. Irradiation at very high doses at specific stages causes detrimental outcomes leading to plant sterility and death. However, at irradiation doses closer to those likely occurring in Space, positive effects, such as an increase in the content of antioxidant compounds, was found. Given that such molecules play an important role in radioprotection and considering altogether the obtained results, tomato Microtom can be considered a valuable candidate for BLSS in Space.

The ionisation parameter of star-forming galaxies evolves with the specific star formation rate

NASA Astrophysics Data System (ADS)

Kaasinen, Melanie; Kewley, Lisa; Bian, Fuyan; Groves, Brent; Kashino, Daichi; Silverman, John; Kartaltepe, Jeyhan

2018-04-01

We investigate the evolution of the ionisation parameter of star-forming galaxies using a high-redshift (z ˜ 1.5) sample from the FMOS-COSMOS survey and matched low-redshift samples from the Sloan Digital Sky Survey. By constructing samples of low-redshift galaxies for which the stellar mass (M*), star formation rate (SFR) and specific star formation rate (sSFR) are matched to the high-redshift sample we remove the effects of an evolution in these properties. We also account for the effect of metallicity by jointly constraining the metallicity and ionisation parameter of each sample. We find an evolution in the ionisation parameter for main-sequence, star-forming galaxies and show that this evolution is driven by the evolution of sSFR. By analysing the matched samples as well as a larger sample of z < 0.3, star-forming galaxies we show that high ionisation parameters are directly linked to high sSFRs and are not simply the byproduct of an evolution in metallicity. Our results are physically consistent with the definition of the ionisation parameter, a measure of the hydrogen ionising photon flux relative to the number density of hydrogen atoms.

Comprehensive chemical comparison of fuel composition and aerosol particles emitted from a ship diesel engine by gas chromatography atmospheric pressure chemical ionisation ultra-high resolution mass spectrometry with improved data processing routines.

PubMed

Rüger, Christopher P; Schwemer, Theo; Sklorz, Martin; O'Connor, Peter B; Barrow, Mark P; Zimmermann, Ralf

2017-02-01

The analysis of petrochemical materials and particulate matter originating from combustion sources remains a challenging task for instrumental analytical techniques. A detailed chemical characterisation is essential for addressing health and environmental effects. Sophisticated instrumentation, such as mass spectrometry coupled with chromatographic separation, is capable of a comprehensive characterisation, but needs advanced data processing methods. In this study, we present an improved data processing routine for the mass chromatogram obtained from gas chromatography hyphenated to atmospheric pressure chemical ionisation and ultra high resolution mass spectrometry. The focus of the investigation was the primary combustion aerosol samples, i.e. particulate matter extracts, as well as the corresponding fossil fuels fed to the engine. We demonstrate that utilisation of the entire transient and chromatographic information results in advantages including minimisation of ionisation artefacts and a reliable peak assignment. A comprehensive comparison of the aerosol and the feed fuel was performed by applying intensity weighted average values, compound class distribution and principle component analysis. Certain differences between the aerosol generated with the two feed fuels, diesel fuel and heavy fuel oil, as well as between the aerosol and the feed were revealed. For the aerosol from heavy fuel oil, oxidised species from the CHN and CHS class precursors of the feed were predominant, whereas the CHO x class is predominant in the combustion aerosol from light fuel oil. Furthermore, the complexity of the aerosol increases significantly compared to the feed and incorporating a higher chemical space. Coupling of atmospheric pressure chemical ionisation to gas chromatography was found to be a useful additional approach for characterisation of a combustion aerosol, especially with an automated utilisation of the information from the ultra-high resolution mass spectrometer and the chromatographic separation.

[Morphology determination of multi-needle bipolar corona discharge by OES].

PubMed

Chen, Hai-Feng; Su, Peng-Hao; Zhu, Yi-Min

2009-01-01

Using the method of OES (optical emission spectrum) for measuring N2 emission spectrum, the spacial distribution of energetic electrons in multi-needle bipolar corona discharge at atmospheric pressure was investigated. According to the distribution of N2 second positive band's intensity ISPB, the outline of ionisation region was drawn accurately. The relationship between ISPB and discharge current I was obtained through the sum of ISPB. There are two ionisation regions in the multi-needle bipolar corona discharge. One is near the HV electrode and the other is near the grounded electrode. The ionisation region exists around the needlepoint within 2-3 mm. The volume of ionisation region becomes big with the applied voltage U increasing. The ionisation region of negative corona is bigger than that of positive corona. Near the HV discharge electrode, the outline of electron avalanche is similar to the configuration of electric field lines in the ionisation region, so the electron avalanche along the axis direction of needle develops farther than that along the radial direction. The electric field in the migration area is weak, and the distribution of space charges is large along the radial direction. The sum of ISPB in each ionisation region is second order linear with I, but the quadratic coefficient is very small. So the sum of ISPB is nearly linear with I, the distribution of ISPB is corresponding to the density distribution of energetic electrons. So the charged particles forming the discharge current in ionisation region are electrons. No emission spectrum of N2 can be measured in migration area, so there is no energetic electron. The energetic electrons only exist in ionisation region and the charged particles in migration area are ions.

Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

NASA Astrophysics Data System (ADS)

Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

2012-06-01

The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

Spectrometre de masse a ionisation Penning selective: Elimination des corrections necessaires a la determination du rapport isotopique de l'hydrogene

NASA Astrophysics Data System (ADS)

Letarte, Sylvain

Dans le but d'ameliorer la precision avec laquelle le rapport isotopique de l'hydrogene peut etre determine, un spectrometre de masse a ionisation Penning a ete construit pour provoquer l'ionisation selective de l'hydrogene moleculaire et de l'hydrure de deuterium a partir d'un melange gazeux. L'utilisation d'atomes dans des etats d'excitation metastable s'est averee une solution adequate pour reponde a cette attente. L'emploi de l'helium, a l'interieur d'une source d'atomes metastables construit specifiquement pour ce travail, ne permet pas d'obtenir un spectre de masse compose uniquement des deux molecules d'interet. L'ionisation de ces dernieres provient de deux processus distincts, soient l'ionisation Penning et l'ionisation par bombardement electronique. Contrairement a l'helium, il a ete demontre que le neon metastable est un candidat ideal pour produire l'ionisation selective de type Penning. Le nombre d'ions produits est directement proportionnel au courant de la decharge electrique et de la pression d'operation de la source d'atomes metastables. Ces resultats demontrent le potentiel d'un tel spectrometre de masse pour ameliorer la precision a laquelle le rapport isotopique peut etre determine comparativement aux autres techniques existantes.

Nurses', physicians' and radiographers' perceptions of the safety of a nurse prescribing of ionising radiation initiative: A cross-sectional survey.

PubMed

Hyde, Abbey; Coughlan, Barbara; Naughton, Corina; Hegarty, Josephine; Savage, Eileen; Grehan, Jennifer; Kavanagh, Eoin; Moughty, Adrian; Drennan, Jonathan

2016-06-01

A new initiative was introduced in Ireland following legislative changes that allowed nurses with special training to prescribe ionising radiation (X-ray) for the first time. A small number of studies on nurse prescribing of ionising radiation in other contexts have found it to be broadly as safe as ionising radiation prescribing by physicians. Sociological literature on perceptions of safety indicates that these tend to be shaped by the ideological position of the professional rather than based on objective evidence. To describe, compare and analyse perceptions of the safety of a nurse prescribing of ionising radiation initiative across three occupational groups: nursing, radiography and medicine. A cross-sectional survey design. Participants were drawn from a range of clinical settings in Ireland. Respondents were 167 health professionals comprised of 49 nurses, 91 radiographers, and 27 physicians out of a total of 300 who were invited to participate. Non-probability sampling was employed and the survey was targeted specifically at health professionals with a specific interest in, or involvement with, the development of the nurse prescribing of ionising radiation initiative in Ireland. Comparisons of perspectives on the safety of nurse prescribing of ionising radiation across the three occupational groups captured by questionnaire were analysed using the Kruskal-Wallis H test. Pairwise post hoc tests were conducted using the Mann-Whitney U test. While the majority of respondents from all three groups perceived nurse prescribing of ionising radiation to be safe, the extent to which this view was held varied. A higher proportion of nurses was found to display confidence in the safety of nurse prescribing of ionising radiation compared to physicians and radiographers with differences between nurses' perceptions and those of the other two groups being statistically significant. That an occupational patterning emerged suggests that perceptions about safety and risk of nurse prescribing of ionising radiation are socially constructed according to the vantage point of the professional and may not reflect objective measures of safety. These findings need to be considered more broadly in the context of ideological barriers to expanding the role of nurses. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cosmic-ray ionisation of dense molecular clouds

NASA Astrophysics Data System (ADS)

Vaupre, Solenn

2015-07-01

Cosmic rays (CR) are of tremendous importance in the dynamical and chemical evolution of interstellar molecular clouds, where stars and planets form. CRs are likely accelerated in the shells of supernova remnants (SNR), thus molecular clouds nearby can be irradiated by intense fluxes of CRs. CR protons have two major effects on dense molecular clouds: 1) when they encounter the dense medium, high-energy protons (>280 MeV) create pions that decay into gamma-rays. This process makes SNR-molecular cloud associations intense GeV and/or TeV sources whose spectra mimic the CR spectrum. 2) at lower energies, CRs penetrate the cloud and ionise the gas, leading to the formation of molecular species characteristic of the presence of CRs, called tracers of the ionisation. Studying these tracers gives information on low-energy CRs that are unaccessible to any other observations. I studied the CR ionisation of molecular clouds next to three SNRs: W28, W51C and W44. These SNRs are known to be interacting with the nearby clouds, from the presence of shocked gas, OH masers and pion-decay induced gamma-ray emission. My work includes millimeter observations and chemical modeling of tracers of the ionisation in these dense molecular clouds. In these three regions, we determined an enhanced CR ionisation rate, supporting the hypothesis of an origin of the CRs in the SNR nearby. The evolution of the CR ionisation rate with the distance to the SNR brings valuable constraints on the propagation properties of low-energy CRs. The method used relies on observations of the molecular ions HCO+ and DCO+, which shows crucial limitations at high ionisation. Therefore, I investigated, both through modeling and observations, the chemical abundances of several other species to try and identity alternative tracers of the ionisation. In particular, in the W44 region, observations of N2H+ bring additional constraints on the physical conditions, volatile abundances in the cloud, and the ionisation state. This research brought valuable insight in to the CR induced chemistry in the interstellar medium. It also brought new perspectives of interdisciplinary research towards the understanding of CRs, from millimeter to gamma-ray observations.

European Code against Cancer 4th Edition: Ionising and non-ionising radiation and cancer.

PubMed

McColl, Neil; Auvinen, Anssi; Kesminiene, Ausrele; Espina, Carolina; Erdmann, Friederike; de Vries, Esther; Greinert, Rüdiger; Harrison, John; Schüz, Joachim

2015-12-01

Ionising radiation can transfer sufficient energy to ionise molecules, and this can lead to chemical changes, including DNA damage in cells. Key evidence for the carcinogenicity of ionising radiation comes from: follow-up studies of the survivors of the atomic bombings in Japan; other epidemiological studies of groups that have been exposed to radiation from medical, occupational or environmental sources; experimental animal studies; and studies of cellular responses to radiation. Considering exposure to environmental ionising radiation, inhalation of naturally occurring radon is the major source of radiation in the population - in doses orders of magnitude higher than those from nuclear power production or nuclear fallout. Indoor exposure to radon and its decay products is an important cause of lung cancer; radon may cause approximately one in ten lung cancers in Europe. Exposures to radon in buildings can be reduced via a three-step process of identifying those with potentially elevated radon levels, measuring radon levels, and reducing exposure by installation of remediation systems. In the 4th Edition of the European Code against Cancer it is therefore recommended to: "Find out if you are exposed to radiation from naturally high radon levels in your home. Take action to reduce high radon levels". Non-ionising types of radiation (those with insufficient energy to ionise molecules) - including extremely low-frequency electric and magnetic fields as well as radiofrequency electromagnetic fields - are not an established cause of cancer and are therefore not addressed in the recommendations to reduce cancer risk. Copyright © 2015 International Agency for Research on Cancer. Published by Elsevier Ltd. All rights reserved.

Matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry-based blood group genotyping--the alternative approach.

PubMed

Gassner, Christoph; Meyer, Stefan; Frey, Beat M; Vollmert, Caren

2013-01-01

Although matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry (MALDI-TOF MS) has previously been reported for high throughput blood group genotyping, those reports are limited to only a few blood group systems. This review describes the development of a large cooperative Swiss-German project, aiming to employ MALDI-TOF MS for the molecular detection of the blood groups Rh, Kell, Kidd, Duffy, MNSs, a comprehensive collection of low incidence antigens, as well as the platelet and granulocyte antigens HPA and HNA, representing a total of 101 blood group antigens, encoded by 170 alleles, respectively. Recent reports describe MALDI-TOF MS as a technology with short time-to-resolution, ability for high throughput, and cost-efficiency when used in genetic analysis, including forensics, pharmacogenetics, oncology and hematology. Furthermore, Kell and RhD genotyping have been performed on fetal DNA from maternal plasma with excellent results. In summary, this article introduces a new technological approach for high throughput blood group genotyping by means of MALDI-TOF MS. Although all data presented are preliminary, the observed success rates, data quality and concordance with known blood group types are highly impressive, underlining the accuracy and reliability of this cost-efficient high throughput method. Copyright © 2013 Elsevier Inc. All rights reserved.

Electron impact ionisation cross section for organoplatinum compounds

NASA Astrophysics Data System (ADS)

Mahato, Dibyendu; Naghma, Rahla; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2016-11-01

This article reports electron impact ionisation cross sections for platinum-based drugs viz., cisplatin (H6N2Cl2Pt), carboplatin (C6H12N2O4Pt), oxaliplatin (C8H14N2O4Pt), nedaplatin (C2H8N2O3Pt) and satraplatin (C10H22ClN2O4Pt) complexes used in the cancer chemotherapy. The multi-scattering centre spherical complex optical potential formalism is used to obtain the inelastic cross section for these large molecules upon electron impact. The ionisation cross section is derived from the inelastic cross section employing complex scattering potential-ionisation contribution method. Comparison is made with previous results, where ever available and overall a reasonable agreement is observed. This is the first attempt to report total ionisation cross sections for nedaplatin and satraplatin complexes.

An improved dispersive solid-phase extraction clean-up method for the gas chromatography-negative chemical ionisation tandem mass spectrometric determination of multiclass pesticide residues in edible oils.

PubMed

Deme, Pragney; Azmeera, Tirupathi; Prabhavathi Devi, B L A; Jonnalagadda, Padmaja R; Prasad, R B N; Vijaya Sarathi, U V R

2014-01-01

An improved sample preparation using dispersive solid-phase extraction clean-up was proposed for the trace level determination of 35 multiclass pesticide residues (organochlorine, organophosphorus and synthetic pyrethroids) in edible oils. Quantification of the analytes was carried out by gas chromatography-mass spectrometry in negative chemical ionisation mode (GC-NCI-MS/MS). The limit of detection and limit of quantification of residues were in the range of 0.01-1ng/g and 0.05-2ng/g, respectively. The analytes showed recoveries between 62% and 110%, and the matrix effect was observed to be less than 25% for most of the pesticides. Crude edible oil samples showed endosulfan isomers, p,p'-DDD, α-cypermethrin, chlorpyrifos, and diazinon residues in the range of 0.56-2.14ng/g. However, no pesticide residues in the detection range of the method were observed in refined oils. Copyright © 2013 Elsevier Ltd. All rights reserved.

Selective laser ionisation of radionuclide 63Ni

NASA Astrophysics Data System (ADS)

Tsvetkov, G. O.; D'yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Firsov, V. A.; Panchenko, V. Ya.

2017-02-01

We report a search for a scheme of selective laser stepwise ionisation of radionuclide 63Ni by radiation of a dye laser pumped by a copper vapour laser. A three-stage scheme is found with ionisation through an autoionising state (AIS): 3d 84s2 3F4(E = 0) → 3d 94p 1Fo3(31030.99 cm-1) → 3d 94d 2[7/2]4(49322.56 cm-1) → AIS(67707.61 cm-1) which, by employing saturated radiation intensities provides the ionisation selectivity of above 1200 for 63Ni.

The Significance of Acid/Base Properties in Drug Discovery

PubMed Central

Manallack, David T.; Prankerd, Richard J.; Yuriev, Elizabeth; Oprea, Tudor I.; Chalmers, David K.

2013-01-01

While drug discovery scientists take heed of various guidelines concerning drug-like character, the influence of acid/base properties often remains under-scrutinised. Ionisation constants (pKa values) are fundamental to the variability of the biopharmaceutical characteristics of drugs and to underlying parameters such as logD and solubility. pKa values affect physicochemical properties such as aqueous solubility, which in turn influences drug formulation approaches. More importantly, absorption, distribution, metabolism, excretion and toxicity (ADMET) are profoundly affected by the charge state of compounds under varying pH conditions. Consideration of pKa values in conjunction with other molecular properties is of great significance and has the potential to be used to further improve the efficiency of drug discovery. Given the recent low annual output of new drugs from pharmaceutical companies, this review will provide a timely reminder of an important molecular property that influences clinical success. PMID:23099561

Peter J Derrick and the Grand Scale 'Magnificent Mass Machine' mass spectrometer at Warwick.

PubMed

Colburn, A W; Derrick, Peter J; Bowen, Richard D

2017-12-01

The value of the Grand Scale 'Magnificent Mass Machine' mass spectrometer in investigating the reactivity of ions in the gas phase is illustrated by a brief analysis of previously unpublished work on metastable ionised n-pentyl methyl ether, which loses predominantly methanol and an ethyl radical, with very minor contributions for elimination of ethane and water. Expulsion of an ethyl radical is interpreted in terms of isomerisation to ionised 3-pentyl methyl ether, via distonic ions and, possibly, an ion-neutral complex comprising ionised ethylcyclopropane and methanol. This explanation is consistent with the closely similar behaviour of the labelled analogues, C 3 H 7 CH 2 CD 2 OCH 3 +. and C 3 H 7 CD 2 CH 2 OCH 3 +. , and is supported by the greater kinetic energy release associated with loss of ethane from ionised n-propyl methyl ether compared to that starting from directly generated ionised 3-pentyl methyl ether.

Mass spectral analysis and imaging of tissue by ToF-SIMS--The role of buckminsterfullerene, C60+, primary ions

NASA Astrophysics Data System (ADS)

Jones, Emrys A.; Lockyer, Nicholas P.; Vickerman, John C.

2007-02-01

Recent developments in desorption/ionisation mass spectrometry techniques have made their application to biological analysis a realistic and successful proposition. Developments in primary ion source technology, mainly through the advent of polyatomic ion beams, have meant that the technique of secondary ion mass spectrometry (SIMS) can now access the depths of information required to allow biological imaging to be a viable option. Here the role of the primary ion C60+ is assessed with regard to molecular imaging of lipids and pharmaceuticals within tissue sections. High secondary ion yields and low surface damage accumulation are demonstrated on both model and real biological samples, indicating the high secondary ion efficiency afforded to the analyst by this primary ion when compared to other cluster ion beams used in imaging. The newly developed 40 keV C60+ ion source allows the beam to be focused such that high resolution imaging is demonstrated on a tissue sample, and the greater yields allow the molecular signal from the drug raclopride to be imaged within tissue section following in vivo dosing. The localisation shown for this drug alludes to issues regarding the chemical environment affecting the ionisation probability of the molecule; the importance of this effect is demonstrated with model systems and the possibility of using laser post-ionisation as a method for reducing this consequence of bio-sample complexity is demonstrated and discussed.

Strong optical field ionisation of solids

NASA Astrophysics Data System (ADS)

McDonald, C. R.; Ben Taher, A.; Brabec, T.

2017-11-01

Population transfer from the valence to conduction band in the presence of an intense laser field is explored theoretically in semiconductors and dielectrics. Experiments performed on dielectrics exposed to an intense laser field have divulged a population dynamics between valence and conduction band that differs from that observed in semiconductors. Our paper explores two aspects of ionisation in solids. (i) Contemporary ionisation theories do not take account of the coupling between the valence and conduction bands resulting in the absence the dynamic Stark shift. Our single-particle analysis identifies the absence of the dynamic Stark shift as a possible cause for the contrasting ionisation behaviours observed in dielectric and semiconductor materials. The dynamic Stark shift results in an increased bandgap as the laser intensity is increased. This suppresses ionisation to an extent where the main population dynamics results from virtual oscillations in the conduction band population. The dynamic Stark shift mainly affects larger bandgap materials which can be exposed to decidedly higher laser intensities. (ii) In the presence of laser dressed virtual population of the conduction band, elastic collisions potentially transmute virtual into real population resulting in ionisation. This process is explored in the context of the relaxation time approximation.

Reactions of the ionized enol tautomer of acetanilide: elimination of HNCO via a novel rearrangement.

PubMed

Heydorn, Lisa N; Carter, Lynn M; Bowen, Richard D; Terlouw, Johan K

2003-01-01

The reactions of ionised acetanilide, C(6)H(5)NH(=O)CH(3)(.+), and its enol, C(6)H(5)NH(OH)=CH(2)(.+), have been studied by a combination of tandem mass spectrometric and computational methods. These two isomeric radical cations have distinct chemistries at low internal energies. The keto tautomer eliminates exclusively CH(2)=C=O to give ionised aniline. In contrast, the enol tautomer loses H-N=C=O, via an unusual skeletal rearrangement, to form predominantly ionised methylene cyclohexadiene. Hydrogen atom loss also occurs from the enol tautomer, with the formation of protonated oxindole. The mechanisms for H-N=C=O and hydrogen atom loss both involve cyclisation; the former proceeds via a spiro transition state formed by attachment of the methylene group to the ipso position, whereas the latter entails the formation of a five-membered ring by attachment to the ortho position. The behaviour of labelled analogues reveals that these two processes have different site selectivities. Hydrogen atom loss involves a reverse critical energy and is subject to an isotope effect. Surprisingly, attempts to promote the enolisation of ionised acetanilide by proton-transport catalysis were unsuccessful. In a reversal of the usual situation for ionised carbonyl compounds, ionised acetanilide is actually more stable than its enol tautomer. The enol tautomer was resistant to proton-transport catalysed ketonisation to ionised acetanilide, possibly because the favoured geometry of the encounter complex with the base molecule is inappropriate for facilitating tautomerisation.

Efficient ionisation of calcium, strontium and barium by resonant laser pumping

NASA Technical Reports Server (NTRS)

Skinner, C. H.

1980-01-01

Efficient ionization has been observed when an atomic vapor of strontium, barium or calcium was illuminated with a long pulse tunable laser at the frequency of the atomic resonance line. The variation in the degree of ionization with neutral density and laser intensity has been measured using the 'hook' method. The maximum ionization observed was 94%. Excited state populations were measured yielding an excitation temperature (depending on exact experimental conditions) in the region of 0.4 eV. The decay of ion density after the laser pulse was monitored and the recombination coefficients determined. The results are interpreted in terms of an electron heating model.

Use of radionuclides in cancer research and treatment.

PubMed

Macías, M T

2009-03-01

Cancer occurs as a result of misregulation of cell growth, which appears to be a consequence of alteration in the function of oncogenes and tumour suppressor genes. Ionising radiation has been used, since the discovery of X-rays in 1896 by Roentgen, both in cancer research and treatment of the disease. The main purpose of cancer research is to understand the molecular alterations involved in the development and progression of the disease in order to improve diagnosis and develop personalised therapies, by focusing on the features of the tumoral cell and the biological events associated to carcinogenesis. Radioisotopic techniques have been used routinely for in vitro research in the molecular and cellular biology of cancer for more than 20 years and are in the process of being substituted by alternative non-radioactive techniques. However in vivo techniques such as irradiation of cells in culture and/or experimental animal models and radioactive labelling are in development, due in part to advances in molecular imaging technologies. The objective of this review is to analyse in an integrative way the applications of ionising radiation in cancer research and therapy. It had been divided into two parts. The first one will approach the techniques applied to cancer research and the second will summarise how ionising radiation is applied to the treatment of neoplastic disease.

Quantifying variability in removal efficiencies of chemicals in activated sludge wastewater treatment plants - a meta-analytical approach.

PubMed

Douziech, Mélanie; Conesa, Irene Rosique; Benítez-López, Ana; Franco, Antonio; Huijbregts, Mark; van Zelm, Rosalie

2018-01-24

Large variations in removal efficiencies (REs) of chemicals have been reported for monitoring studies of activated sludge wastewater treatment plants (WWTPs). In this work, we conducted a meta-analysis on REs (1539 data points) for a set of 209 chemicals consisting of fragrances, surfactants, and pharmaceuticals in order to assess the drivers of the variability relating to inherent properties of the chemicals and operational parameters of activated sludge WWTPs. For a reduced dataset (n = 542), we developed a mixed-effect model (meta-regression) to explore the observed variability in REs for the chemicals using three chemical specific factors and four WWTP-related parameters. The overall removal efficiency of the set of chemicals was 82.1% (95% CI 75.2-87.1%, N = 1539). Our model accounted for 17% of the total variability in REs, while the process-based model SimpleTreat did not perform better than the average of the measured REs. We identified that, after accounting for other factors potentially influencing RE, readily biodegradable compounds were better removed than non-readily biodegradable ones. Further, we showed that REs increased with increasing sludge retention times (SRTs), especially for non-readily biodegradable compounds. Finally, our model highlighted a decrease in RE with increasing K OC . The counterintuitive relationship to K OC stresses the need for a better understanding of electrochemical interactions influencing the RE of ionisable chemicals. In addition, we highlighted the need to improve the modelling of chemicals that undergo deconjugation when predicting RE. Our meta-analysis represents a first step in better explaining the observed variability in measured REs of chemicals. It can be of particular help to prioritize the improvements required in existing process-based models to predict removal efficiencies of chemicals in WWTPs.

Radiation safety.

PubMed

Skinner, Sarah

2013-06-01

Diagnostic radiology procedures, such as computed tomography (CT) and X-ray, are an increasing source of ionising radiation exposure to our community. Exposure to ionising radiation is associated with increased risk of malignancy, proportional to the level of exposure. Every diagnostic test using ionising radiation needs to be justified by clinical need. General practitioners need a working knowledge of radiation safety so they can adequately inform their patients of the risks and benefits of diagnostic imaging procedures.

Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate.

PubMed

Kowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro

2014-12-01

The 6- to 7-MeV high-energy gamma-ray calibration field by the (19)F(p, αγ)(16)O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma-ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Qualitative and quantitative determination of yohimbine in authentic yohimbe bark and in commercial aphrodisiacs by HPLC-UV-API/ MS methods.

PubMed

Zanolari, Boris; Ndjoko, Karine; Ioset, Jean-Robert; Marston, Andrew; Hostettmann, Kurt

2003-01-01

The development and validation of a rapid qualitative and quantitative method based on an HPLC-UV-MS technique with atmospheric pressure chemical ionisation and electrospray ionisation for the analysis of yohimbine in a number of commercial aphrodisiac products is reported. HPLC with multiple-stage mass spectrometry experiments allowed the identification of the target compound and increased the selectivity of complex analyses such as those involved with multi-botanical preparations. The precision and the robustness of the method were improved by the use of two internal standards: codeine for UV detection and deuterium-labelled yohimbine for MS detection. Twenty commercial aphrodisiac preparations were analysed and the amount of yohimbine measured and expressed as the maximal dose per day suggested on product labels ranged from 1.32 to 23.16 mg.

Improved radiation tolerance of MAPS using a depleted epitaxial layer

NASA Astrophysics Data System (ADS)

Dorokhov, A.; Bertolone, G.; Baudot, J.; Brogna, A. S.; Colledani, C.; Claus, G.; De Masi, R.; Deveaux, M.; Dozière, G.; Dulinski, W.; Fontaine, J.-C.; Goffe, M.; Himmi, A.; Hu-Guo, Ch.; Jaaskelainen, K.; Koziel, M.; Morel, F.; Santos, C.; Specht, M.; Valin, I.; Voutsinas, G.; Wagner, F. M.; Winter, M.

2010-12-01

Tracking performance of Monolithic Active Pixel Sensors (MAPS) developed at IPHC (Turchetta, et al., 2001) [1] have been extensively studied (Winter, et al., 2001; Gornushkin, et al., 2002) [2,3]. Numerous sensor prototypes, called MIMOSA, were fabricated and tested since 1999 in order to optimise the charge collection efficiency and power dissipation, to minimise the noise and to increase the readout speed. The radiation tolerance was also investigated. The highest fluence tolerable for a 10 μm pitch device was found to be ˜1013 neq/cm2, while it was only 2×1012 neq/cm2 for a 20 μm pitch device. The purpose of this paper is to show that the tolerance to non-ionising radiation may be extended up to O(10 14) n eq/cm 2. This goal relies on a fabrication process featuring a 15 μm thin, high resistivity ( ˜1 kΩ cm) epitaxial layer. A sensor prototype (MIMOSA-25) was fabricated in this process to explore its detection performance. The depletion depth of the epitaxial layer at standard CMOS voltages ( <5 V) is similar to the layer thickness. Measurements with m.i.p.s show that the charge collected in the seed pixel is at least twice larger for the depleted epitaxial layer than for the undepleted one, translating into a signal-to-noise ratio (SNR) of ˜50. Tests after irradiation have shown that this excellent performance is maintained up to the highest fluence considered ( 3×1013 neq/cm2), making evidence of a significant extension of the radiation tolerance limits of MAPS. Standing for minimum ionising particle.

Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z 0.7

NASA Astrophysics Data System (ADS)

Epinat, B.; Contini, T.; Finley, H.; Boogaard, L. A.; Guérou, A.; Brinchmann, J.; Carton, D.; Michel-Dansac, L.; Bacon, R.; Cantalupo, S.; Carollo, M.; Hamer, S.; Kollatschny, W.; Krajnović, D.; Marino, R. A.; Richard, J.; Soucail, G.; Weilbacher, P. M.; Wisotzki, L.

2018-01-01

We report the discovery of a 104 kpc2 gaseous structure detected in [O II]λλ3727, 3729 in an over-dense region of the COSMOS-Gr30 galaxy group at z 0.725 with deep MUSE Guaranteed Time Observations. We estimate the total amount of diffuse ionised gas to be of the order of ( 5 ± 3) × 1010 M⊙ and explore its physical properties to understand its origin and the source(s) of the ionisation. The MUSE data allow the identification of a dozen group members that are embedded in this structure through emission and absorption lines. We extracted spectra from small apertures defined for both the diffuse ionised gas and the galaxies. We investigated the kinematics and ionisation properties of the various galaxies and extended gas regions through line diagnostics (R23, O32, and [O III]/Hβ) that are available within the MUSE wavelength range. We compared these diagnostics to photo-ionisation models and shock models. The structure is divided into two kinematically distinct sub-structures. The most extended sub-structure of ionised gas is likely rotating around a massive galaxy and displays filamentary patterns that link some galaxies. The second sub-structure links another massive galaxy that hosts an active galactic nucleus (AGN) to a low-mass galaxy, but it also extends orthogonally to the AGN host disc over 35 kpc. This extent is likely ionised by the AGN itself. The location of small diffuse regions in the R23 vs. O32 diagram is compatible with photo-ionisation. However, the location of three of these regions in this diagram (low O32, high R23) can also be explained by shocks, which is supported by their high velocity dispersions. One edge-on galaxy shares the same properties and may be a source of shocks. Regardless of the hypothesis, the extended gas seems to be non-primordial. We favour a scenario where the gas has been extracted from galaxies by tidal forces and AGN triggered by interactions between at least the two sub-structures. Based on observations made with ESO telescopes at the Paranal Observatory under programs 094.A-0247 and 095.A-0118.

The effectiveness of photocatalytic ionisation disinfection of filter materials.

PubMed

Pietrzak, Katarzyna; Gutarowska, Beata

2013-01-01

The purpose of this study was to determine the effectiveness of photocatalytic ionisation as a disinfection method for filter materials contaminated by microorganisms, and to assess how air relative humidity (RH), time and microbe type influence the effectiveness of this disinfection. In the quantitative analysis of a used car air filter, bacterial contamination equalled 1.2 x 10(5) cfu/cm2, fungal contamination was 3.8 x 10(6) cfu/cm2, and the isolated microorganisms were Aspergillus niger, Bacillus megaterium, Cladosporium herbarum, Cryptococcus laurenti, Micrococcus sp., Rhodotorula glutinis and Staphylococcus cohnii. In the model experiment, three isolates (C. herbarum, R. glutinis, S. cohnii) and 3 ATCC species (A. niger, E. coli, S. aureus) were used for photocatalytic ionisation disinfection. The conditions of effective photocatalytic ionisation disinfection (R > or = 99.9%) were established as 2-3 h at RH = 77% (bacteria) and 6-24 h at RH = 53% (fungi). RH has an influence on the effectiveness of the photocatalytic disinfection process; the highest effectiveness was obtained for bacteria at RH = 77%, with results 5% higher than for RH = 49%. The studies show that the sensitivity of microorganisms to photocatalytic ionisation disinfection is ordered as follows: Gram-positive bacteria (S. cohnii, S. aureus), Gram-negative bacteria (E. coli), yeasts (R. glutinis), and moulds (C. herbarum, A. niger). Of all the mathematical models used for the description of death dynamics after photocatalytic ionisation disinfection, the Chick-Watson model is the most useful, but for more resistant microorganisms, the delayed Chick-Watson model is highly recommended. It therefore seems, that the presented disinfection method of photocatalytic ionisation can be successfully used to clean filtration materials.

A special ionisation chamber for quality control of diagnostic and mammography X ray equipment.

PubMed

Costa, A M; Caldas, L V E

2003-01-01

A quality control program for X ray equipment used for conventional radiography and mammography requires the constancy check of the beam qualities in terms of the half-value layers. In this work, a special double-faced parallel-plate ionisation chamber was developed with inner electrodes of different materials, in a tandem system. Its application will be in quality control programs of diagnostic and mammography X ray equipment for confirmation of half-value layers previously determined by the conventional method. Moreover, the chamber also may be utilised for measurements of air kerma values (and air kerma rates) in X radiation fields used for conventional radiography and mammography. The chamber was studied in relation to the characteristics of saturation, ion collection efficiency, polarity effects, leakage current, and short-term stability. The energy dependence in response of each of the two faces of the chamber was determined over the conventional radiography and mammography X ray ranges (unattenuated beams). The different energy response of the two faces of the chamber allowed the formation of a tandem system useful for the constancy check of beam qualities.

Ultra-high-performance supercritical fluid chromatography with quadrupole-time-of-flight mass spectrometry (UHPSFC/QTOF-MS) for analysis of lignin-derived monomeric compounds in processed lignin samples.

PubMed

Prothmann, Jens; Sun, Mingzhe; Spégel, Peter; Sandahl, Margareta; Turner, Charlotta

2017-12-01

The conversion of lignin to potentially high-value low molecular weight compounds often results in complex mixtures of monomeric and oligomeric compounds. In this study, a method for the quantitative and qualitative analysis of 40 lignin-derived compounds using ultra-high-performance supercritical fluid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPSFC/QTOF-MS) has been developed. Seven different columns were explored for maximum selectivity. Makeup solvent composition and ion source settings were optimised using a D-optimal design of experiment (DoE). Differently processed lignin samples were analysed and used for the method validation. The new UHPSFC/QTOF-MS method showed good separation of the 40 compounds within only 6-min retention time, and out of these, 36 showed high ionisation efficiency in negative electrospray ionisation mode. Graphical abstract A rapid and selective method for the quantitative and qualitative analysis of 40 lignin-derived compounds using ultra-high-performance supercritical fluid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPSFC/QTOF-MS).

Medical exposure to ionising radiation and the risk of brain tumours: Interphone study group, Germany.

PubMed

Blettner, Maria; Schlehofer, Brigitte; Samkange-Zeeb, Florence; Berg, Gabriele; Schlaefer, Klaus; Schüz, Joachim

2007-09-01

The role of exposure to low doses of ionising radiation in the aetiology of brain tumours has yet to be clarified. The objective of this study was to investigate the association between medically or occupationally related exposure to ionising radiation and brain tumours. We used self-reported medical and occupational data collected during the German part of a multinational case-control study on mobile phone use and the risk of brain tumours (Interphone study) for the analyses. For any exposure to medical ionising radiation we found odds ratios (ORs) of 0.63 (95% confidence interval (CI)=0.48-0.83), 1.08 (95% CI=0.80-1.45) and 0.97 (95% CI=0.54-1.75) for glioma, meningioma and acoustic neuroma, respectively. Elevated ORs were found for meningioma (OR 2.32, 95% CI: 0.90-5.96) and acoustic neuroma (OR 6.45, 95% CI: 0.62-67.16) for radiotherapy to the head and neck regions. We did not find any significant increased risk of brain tumours for exposure to medical ionising radiation.

Investigation of colloidal graphite as a matrix for matrix-assisted laser desorption/ionisation mass spectrometry of low molecular weight analytes.

PubMed

Warren, Alexander D; Conway, Ulric; Arthur, Christopher J; Gates, Paul J

2016-07-01

The analysis of low molecular weight compounds by matrix-assisted laser desorption/ionisation mass spectrometry is problematic due to the interference and suppression of analyte ionisation by the matrices typically employed - which are themselves low molecular weight compounds. The application of colloidal graphite is demonstrated here as an easy to use matrix that can promote the ionisation of a wide range of analytes including low molecular weight organic compounds, complex natural products and inorganic complexes. Analyte ionisation with colloidal graphite is compared with traditional organic matrices along with various other sources of graphite (e.g. graphite rods and charcoal pencils). Factors such as ease of application, spectra reproducibility, spot longevity, spot-to-spot reproducibility and spot homogeneity (through single spot imaging) are explored. For some analytes, considerable matrix suppression effects are observed resulting in spectra completely devoid of matrix ions. We also report the observation of radical molecular ions [M(-●) ] in the negative ion mode, particularly with some aromatic analytes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.

PubMed

Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

2007-01-01

Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material. Copyright (c) 2007 John Wiley & Sons, Ltd.

Improving Preservice Chemistry Teachers' Content Knowledge through Intervention Activities

ERIC Educational Resources Information Center

Wheeldon, Ruth

2017-01-01

The effect of intervention activities on the chemistry content knowledge of 92 preservice chemistry teachers (PSCT) was examined via a pre and post true/false with confidence level test focusing on ionisation energy values and the use of a common alternative conception (AC). Data were collected from three cohorts of PSCT each engaged in a one year…

Preparation of 'near' homogeneous samples for the analysis of matrix-assisted laser desorption/ionisation processes

NASA Astrophysics Data System (ADS)

Allwood, D. A.; Perera, I. K.; Perkins, J.; Dyer, P. E.; Oldershaw, G. A.

1996-11-01

Highly uniform thin films of samples for matrix-assisted laser desorption/ionisation (MALDI) have been fabricated by depositing a saturated solution of ferulic acid onto a soda lime glass disc and crushing with polished aluminium, the films covering large areas of the substrate and having a thickness between 45-60 μm. The effects that different substrates and crushing materials as well as sample concentration and sample recrystallisation have on these films has been examined by scanning electron microscopy. Such films have been shown to have a lower threshold fluence for matrix ion detection than standard dried-droplet samples, the reduction being approximately 15% for three of the five matrices analysed. An explanation for this is proposed in terms of crushed samples possessing a greater average energy per unit volume coupled to them by the laser due to their improved surface uniformity. Furthermore, samples that are dried at refrigerated temperatures (˜ 2.25°C) are shown to have a much improved macroscopic uniformity over samples dried at room temperature. Refrigerated and crushed MALDI samples yield analyte ions with good spot-to-spot and pulse-to-pulse reproducibility and both preparation steps appear to improve the resolution of spectra obtained with a time-of-flight mass spectrometer.

Gastrointestinal radiation injury: prevention and treatment.

PubMed

Shadad, Abobakr K; Sullivan, Frank J; Martin, Joseph D; Egan, Laurence J

2013-01-14

With the recent advances in detection and treatment of cancer, there is an increasing emphasis on the efficacy and safety aspects of cancer therapy. Radiation therapy is a common treatment for a wide variety of cancers, either alone or in combination with other treatments. Ionising radiation injury to the gastrointestinal tract is a frequent side effect of radiation therapy and a considerable proportion of patients suffer acute or chronic gastrointestinal symptoms as a result. These side effects often cause morbidity and may in some cases lower the efficacy of radiotherapy treatment. Radiation injury to the gastrointestinal tract can be minimised by either of two strategies: technical strategies which aim to physically shift radiation dose away from the normal intestinal tissues, and biological strategies which aim to modulate the normal tissue response to ionising radiation or to increase its resistance to it. Although considerable improvement in the safety of radiotherapy treatment has been achieved through the use of modern optimised planning and delivery techniques, biological techniques may offer additional further promise. Different agents have been used to prevent or minimize the severity of gastrointestinal injury induced by ionising radiation exposure, including biological, chemical and pharmacological agents. In this review we aim to discuss various technical strategies to prevent gastrointestinal injury during cancer radiotherapy, examine the different therapeutic options for acute and chronic gastrointestinal radiation injury and outline some examples of research directions and considerations for prevention at a pre-clinical level.

Ionisation in turbulent magnetic molecular clouds. I. Effect on density and mass-to-flux ratio structures

NASA Astrophysics Data System (ADS)

Bailey, Nicole D.; Basu, Shantanu; Caselli, Paola

2017-05-01

Context. Previous studies show that the physical structures and kinematics of a region depend significantly on the ionisation fraction. These studies have only considered these effects in non-ideal magnetohydrodynamic simulations with microturbulence. The next logical step is to explore the effects of turbulence on ionised magnetic molecular clouds and then compare model predictions with observations to assess the importance of turbulence in the dynamical evolution of molecular clouds. Aims: In this paper, we extend our previous studies of the effect of ionisation fractions on star formation to clouds that include both non-ideal magnetohydrodynamics and turbulence. We aim to quantify the importance of a treatment of the ionisation fraction in turbulent magnetised media and investigate the effect of the turbulence on shaping the clouds and filaments before star formation sets in. In particular, here we investigate how the structure, mass and width of filamentary structures depend on the amount of turbulence in ionised media and the initial mass-to-flux ratio. Methods: To determine the effects of turbulence and mass-to-flux ratio on the evolution of non-ideal magnetised clouds with varying ionisation profiles, we have run two sets of simulations. The first set assumes different initial turbulent Mach values for a fixed initial mass-to-flux ratio. The second set assumes different initial mass-to-flux ratio values for a fixed initial turbulent Mach number. Both sets explore the effect of using one of two ionisation profiles: step-like (SL) or cosmic ray only (CR-only). We compare the resulting density and mass-to-flux ratio structures both qualitatively and quantitatively via filament and core masses and filament fitting techniques (Gaussian and Plummer profiles). Results: We find that even with almost no turbulence, filamentary structure still exists although at lower density contours. Comparison of simulations shows that for turbulent Mach numbers above 2, there is little structural difference between the SL and CR-only models, while below this threshold the ionisation structure significantly affects the formation of filaments. This holds true for both sets of models. Analysis of the mass within cores and filaments shows that the mass decreases as the degree of turbulence increases. Finally, observed filaments within the Taurus L1495/B213 complex are best reproduced by models with supercritical mass-to-flux ratios and/or at least mildly supersonic turbulence, however, our models show that the sterile fibres observed within Taurus may occur in highly ionised, subcritical environments. Conclusions: From the analysis of the simulations, we conclude that in the presence of low turbulent velocities, the ionisation structure of the medium still plays a role in shaping the structure of the cloud, however, above Mach 2, the differences between the two profiles become indistinguishable. However, differences may be present in the underlying velocity structure. Kinematics studies will be the focus of the next paper in this series. Regions with fertile fibres likely indicate a trans- or supercritical mass-to-flux ratio within the region while sterile fibres are likely subcritical and transient.

Determination of Energy of a Clinical Electron Beam as Part of a Routine Quality Assurance and Audit System

NASA Astrophysics Data System (ADS)

Hernández-Bello, Jimmy; D'Souza, Derek; Rossenberg, Ivan

2002-08-01

A method to determine the electron beam energy and an electron audit based on the current IPEM electron Code of Practice has been devised. During the commissioning on the new Varian 2100CD linear accelerator in The Middlesex Hospital, two methods were devised for the determination of electron energy. The first method involves the use of a two-depth method, whereby the ratio of ionisation (presented as a percentage) measured by an ion chamber at two depths in solid water is used to compare against the baseline ionisation depth value for that energy. The second method involves the irradiation of an X-ray film in solid water to obtain a depth dose curve and, hence determine the half value depth and practical range of the electrons. The results showed that the two-depth method has a better accuracy, repeatability, reliability and consistency than the X-ray method. The results for the electron audit showed that electron absolute outputs are obtained from ionisation measurements in solid water, where the energy-range parameters such as practical range and the depth at which ionisation is 50% of that at the maximum for the depth-ionisation curve are determined.

Ionisation in ultra-cool, cloud forming extrasolar planetary atmospheres

NASA Astrophysics Data System (ADS)

Helling, Christiane; the LEAP Team

2015-04-01

Transit spectroscopy provides evidence that extrasolare planets are covered in clouds, a finding that has been forecast by cloud model simulations 15 years ago. Atmospheres are strongly affected by clouds through their large opacity and their chemical activity. Cloud formation models allow to predict cloud particle sizes, their chemical composition and the composition of the remaining atmospheric gas (Woitke & Helling 2004, A&A 414; Helling & Woitke 2006, A&A 455), for example, as input for radiative transfer codes like Drift-Phoenix (Witte et al. 2009; A&A 506). These cloud particles are charged and can discharge, for example in form of lighting (Helling et al. 2013, ApJ 767; Bailey et al. 2014, ApJ 784). Earth observations demonstrate that lighting effects not only the local chemistry but also the electron budget of the atmosphere. This talk will present our work on cloud formation modelling and ionisation processes in cloud forming atmospheres. An hierarchy of ionisation processes leads to a vertically inhomogenously ionised atmosphere which has implications for planetary mass loss and global circulation pattern of planetary atmospheres. Processes involved, like Cosmic Ray ionisation, do also activate the local chemistry such that large hydrocarbon molecules form (Rimmer et al. 2014, IJAsB 13).

Concentration-dependent effect of hypocalcaemia on in vitro clot strength in patients at risk of bleeding: a retrospective cohort study.

PubMed

Ho, K M; Yip, C B

2016-02-01

It is uncertain whether hypocalcaemia is associated with an increased risk of bleeding. This study assessed the dose-related relationship between ionised calcium concentrations and in vitro clot strength measured by maximum amplitude (MA) on the thromboelastograph (TEG). A total of 610 patients who were at risk of bleeding or had active bleeding between 2010 and 2014 were considered in this retrospective cohort study. A scatter plot with Pearson correlation coefficient (r) and multiple linear regression was used to assess the dose-related relationship between ionised calcium concentrations and MA on the TEG. The mean ionised calcium of the patients was 1·10 mmol L(-1) (interquartile range: 1·04-1·17) and 235 (38·5%) of them had hypocalcaemia (<1·1 mmol L(-1) ). Hypocalcaemia was more common in patients with significant coexisting coagulopathy. Ionised calcium concentrations (r = 0·285, 95% confidence interval (CI) 0·211-0·356, P = 0·001), as well as fibrinogen concentrations, platelet counts, international normalised ratio (INR) and activated Partial Thromboplastin Time (aPTT), had a significant linear correlation with the MA on the TEG. Ionised calcium concentrations and its interaction term with platelet count were both significantly associated with the MA on the TEG (slope of the regression line 1·1 per 0·1 mmol L(-1) increment, 95%CI 0·3 to 1·9, P = 0·011), after adjusting for fibrinogen concentrations, platelet counts, INR and aPTT. Ionised calcium concentrations had a concentration-dependent association with in vitro clot strength after adjusting for other coagulation abnormalities in patients with coexisting coagulopathy. Maintaining a normal ionised calcium concentration, >1 mmol L(-1) , during critical bleeding is recommended. © 2016 British Blood Transfusion Society.

Developing an in silico model of the modulation of base excision repair using methoxyamine for more targeted cancer therapeutics.

PubMed

Gurkan-Cavusoglu, Evren; Avadhani, Sriya; Liu, Lili; Kinsella, Timothy J; Loparo, Kenneth A

2013-04-01

Base excision repair (BER) is a major DNA repair pathway involved in the processing of exogenous non-bulky base damages from certain classes of cancer chemotherapy drugs as well as ionising radiation (IR). Methoxyamine (MX) is a small molecule chemical inhibitor of BER that is shown to enhance chemotherapy and/or IR cytotoxicity in human cancers. In this study, the authors have analysed the inhibitory effect of MX on the BER pathway kinetics using a computational model of the repair pathway. The inhibitory effect of MX depends on the BER efficiency. The authors have generated variable efficiency groups using different sets of protein concentrations generated by Latin hypercube sampling, and they have clustered simulation results into high, medium and low efficiency repair groups. From analysis of the inhibitory effect of MX on each of the three groups, it is found that the inhibition is most effective for high efficiency BER, and least effective for low efficiency repair.

Electron-induced scattering dynamics of Boron, Aluminium and Gallium trihalides in the intermediate energy domain

NASA Astrophysics Data System (ADS)

Verma, Pankaj; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2018-05-01

This article is focused on the calculation of electron-induced ionisation and total scattering cross sections by Boron, Aluminium and Gallium trihalide molecules in the intermediate energy domain. The computational formalism, spherical complex optical potential has been employed for the study of these two scattering cross sections. The ionisation cross section has been derived from the inelastic cross section using a semi-empirical method called complex scattering potential-ionisation contribution (CSP-ic) method. We have also calculated the ionisation cross section using the BEB theory with Hartree-Fock and density functional theory (DFT- ωB97XD) orbitals so that a comparison can be made with the cross sections predicted by CSP-ic method. For this theoretical study, we have also calculated polarisability and bond length of some targets which were not found in literature using DFT/B3LYP in Gaussian 09 software.

Ionising radiation risk disclosure: When should radiographers assume a duty to inform?

PubMed

Younger, C W E; Douglas, C; Warren-Forward, H

2018-05-01

Autonomy is a fundamental patient right for ethical practice, and informed consent is the mechanism by which health care professionals ensure this right has been respected. The ethical notion of informed consent has evolved alongside legal developments. Under Australian law, a provider who fails to disclose risk may be found to be in breach of a duty of disclosure, potentially facing legal consequences if the patient experiences harm that is attributable to an undisclosed risk. These consequences may include the common law tort of negligence. Ionising radiation, in the form of a medical imaging examination, has the potential to cause harm. However, stochastic effects cannot be attributable to a specific ionising radiation event. What then is the role of the Australian medical imaging service provider in disclosing ionising radiation risk? The ethical and legal principles of informed consent, and the duty of information provision to the patient are investigated. These general principles are then applied to the specific and unusual case of ionising radiation, and what responsibilities apply to the medical imaging provider. Finally, the legal, professional and ethical duties of the radiographer to disclose information to their patients are investigated. Australian law is unclear as to whether a radiographer has a common law responsibility to disclose radiation risk. There is ambiguity as to whether stochastic ionising radiation risk could be considered a legal disclosure responsibility. While it is unlikely that not disclosing risk will have medicolegal consequences, doing so represents sound ethical practice. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Correlation of the ionisation response at selected points of IC sensitive regions with SEE sensitivity parameters under pulsed laser irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordienko, A V; Mavritskii, O B; Egorov, A N

2014-12-31

The statistics of the ionisation response amplitude measured at selected points and their surroundings within sensitive regions of integrated circuits (ICs) under focused femtosecond laser irradiation is obtained for samples chosen from large batches of two types of ICs. A correlation between these data and the results of full-chip scanning is found for each type. The criteria for express validation of IC single-event effect (SEE) hardness based on ionisation response measurements at selected points are discussed. (laser applications and other topics in quantum electronics)

The influence of non-ionisable excipients on precipitation parameters measured using the CheqSol method.

PubMed

Etherson, Kelly; Halbert, Gavin; Elliott, Moira

2016-09-01

The aim of this study was to determine the influence of non-ionisable excipients hydroxypropyl-β-cyclodextrin (HPβCD) and poloxamers 407 and 188 on the supersaturation and precipitation kinetics of ibuprofen, gliclazide, propranolol and atenolol induced through solution pH shifts using the CheqSol method. The drug's kinetic and intrinsic aqueous solubilities were measured in the presence of increasing excipient concentrations using the CheqSol method. Experimental data rate of change of pH with time was also examined to determine excipient-induced parachute effects and influence on precipitation rates. The measured kinetic and intrinsic solubilities provide a determination of the influence of each excipient on supersaturation index, and the area under the CheqSol curve can measure the parachute capability of excipients. The excipients influence on precipitation kinetics can be measured with novel parameters; for example, the precipitation pH or percentage ionised drug at the precipitation point, which provide further information on the excipient-induced changes in precipitation performance. This method can therefore be employed to measure the influence of non-ionisable excipients on the kinetic solubility behaviour of supersaturated solutions of ionisable drugs and to provide data, which discriminates between excipient systems during precipitation. © 2016 Royal Pharmaceutical Society.

COSPAR/PRBEM international working group activities report

NASA Astrophysics Data System (ADS)

Bourdarie, S.; Blake, B.; Cao, J. B.; Friedel, R.; Miyoshi, Y.; Panasyuk, M.; Underwood, C.

It is now clear to everybody that the current standard AE8 AP8 model for ionising particle specification in the radiation belts must be updated But such an objective is quite difficult to reach just as a reminder to develop AE8 AP8 model in the seventies was 10 persons full time for ten years It is clear that world-wide efforts must be combined because not any individual group has the human resource to perform these new models by themselves Under COSPAR umbrella an international group of expert well distributed around the world has been created to set up a common framework for everybody involved in this field Planned activities of the international group of experts are to - Define users needs - Provide guidelines for standard file format for ionising measurements - Set up guidelines to process in-situ data on a common basis - Decide in which form the new models will have to be - Centralise all progress done world-wide to advise the community - Try to organise world-wide activities as a project to ensure complementarities and more efficiencies between all efforts done Activities of this working group since its creation will be reported as well as future plans

An efficient method for the simultaneous determination of furan, 2-methylfuran and 2-pentylfuran in fruit juices by headspace solid phase microextraction and gas chromatography-flame ionisation detector.

PubMed

Hu, Gaofei; Zhu, Yan; Hernandez, Marta; Koutchma, Tatiana; Shao, Suqin

2016-02-01

A headspace solid phase microextraction (HS-SPME) procedure followed by gas chromatography-flame ionisation detector (GC-FID) analysis was developed and validated for the simultaneous analysis of furan, 2-methylfuran and 2-pentylfuran from juice samples. Extraction at 32 °C for 20 min with stirring at 600 rpm and NaCl concentration 15% (W/V) was the optimal HS-SPME condition for all the three compounds by using a carboxen/polydimethylsiloxane fused silica fibre (75 μm). The extracted compounds were base line separated on a SPB-1 GC column within 12 min. The relative standard deviations of all analytes were less than 6.7%. The recovery rates were between 90.2% and 110.1%. The limits of detection and limits of quantification were 0.056-0.23 ng/mL and 0.14-0.76 ng/mL, respectively. The results showed that the developed method was sensitive, precise, accurate and robust for the determination of furan, 2-methylfuran and 2-pentylfuran in complex matrices without interferences from other components. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Use of high-performance liquid chromatography with diode array detection coupled to electrospray-Qq-time-of-flight mass spectrometry for the direct characterization of the phenolic fraction in organic commercial juices.

PubMed

Rodríguez-Medina, I C; Segura-Carretero, A; Fernández-Gutiérrez, A

2009-06-05

We have developed a direct method for the qualitative analysis of polyphenols in commercial organic fruit juices. The juices were diluted with water (50/50), filtered and directly injected. The analysis of phenolic compounds was carried out by reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to photodiode array detection (DAD) and electrospray ionisation-Qq-time-of-flight mass spectrometry (ESI-Qq-TOF-MS). A unique gradient program has been optimized for the separation of several phenolic classes and the analysis time was only 5 min. The fruit juice samples were successfully analysed in positive and negative ionisation modes. In positive mode the anthocyanins were identified whereas the vast majority of polyphenols were identified using the negative ionisation mode. The sensitivity, together with mass accuracy and true isotopic pattern of the Qq-TOF-MS, allowed the identification of the phenolic compounds. Moreover, the advantage of the proposed method is the combined search of MS and MS/MS spectra, which improves the identification of compounds considerably, reducing ambiguities and false positive hits. Therefore the total fragmentation of the compound ion leading to the aglycone ion or other fragments was corroborated by MS-MS. The method was successfully employed to characterize diverse phenolic families in commercially available organic juices from four different fruits and consequently could be used in the future for the quantification purposes to compare different content of polyphenols in juices.

Rapid detection of nicotine from breath using desorption ionisation on porous silicon.

PubMed

Guinan, T M; Abdelmaksoud, H; Voelcker, N H

2017-05-04

Desorption ionisation on porous silicon (DIOS) was used for the detection of nicotine from exhaled breath. This result represents proof-of-principle of the ability of DIOS to detect small molecular analytes in breath including biomarkers and illicit drugs.

Phenomenological study of the ionisation density-dependence of TLD-100 peak 5a.

PubMed

Brandan, Maria-Ester; Angeles, Oscar; Mercado-Uribe, Hilda

2006-01-01

Horowitz and collaborators have reported evidence on the structure of TLD-100 peak 5. A satellite peak, called 5a, has been singled out as arising from localised electron-hole recombination in a trap/luminescent centre, its emission mechanism would be geminate recombination and, therefore, its population would depend on incident radiation ionisation density. We report a phenomenological study of peak 4, 5a and 5 strengths for glow curves previously measured at UNAM for gammas, electrons and low-energy ions. The deconvolution procedure has followed strict rules to assure that the glow curve, where the presence of peak 5a is not visually noticeable, is decomposed in a consistent fashion, maintaining fixed widths and relative temperature difference between all the peaks. We find no improvement in the quality of the fit after inclusion of peak 5a. The relative contribution of peak 5a with respect to peak 5 does not seem to correlate with the radiation linear energy transfer.

Characterisation of organometallic and coordination compounds by solvent-free matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.

PubMed

Wyatt, Mark F; Stein, Bridget K; Brenton, A Gareth

2008-01-01

Insoluble or low solubility organometallic and coordination compounds have been characterised by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, with solvent-free sample preparation being the key step toward successful analysis.

Matrix-free mass spectrometric imaging using laser desorption ionisation Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Goodwin, Richard J A; Pitt, Andrew R; Harrison, David; Weidt, Stefan K; Langridge-Smith, Pat R R; Barrett, Michael P; Logan Mackay, C

2011-04-15

Mass spectrometry imaging (MSI) is a powerful tool in metabolomics and proteomics for the spatial localization and identification of pharmaceuticals, metabolites, lipids, peptides and proteins in biological tissues. However, sample preparation remains a crucial variable in obtaining the most accurate distributions. Common washing steps used to remove salts, and solvent-based matrix application, allow analyte spreading to occur. Solvent-free matrix applications can reduce this risk, but increase the possibility of ionisation bias due to matrix adhesion to tissue sections. We report here the use of matrix-free MSI using laser desorption ionisation performed on a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. We used unprocessed tissue with no post-processing following thaw-mounting on matrix-assisted laser desorption ionisation (MALDI) indium-tin oxide (ITO) target plates. The identification and distribution of a range of phospholipids in mouse brain and kidney sections are presented and compared with previously published MALDI time-of-flight (TOF) MSI distributions. Copyright © 2011 John Wiley & Sons, Ltd.

Ionised outflows in z ~ 2.4 quasar host galaxies

NASA Astrophysics Data System (ADS)

Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

2015-08-01

Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, P.ID: 086.B-0579(A).

Secondary ionisations in a wall-less ion-counting nanodosimeter: quantitative analysis and the effect on the comparison of measured and simulated track structure parameters in nanometric volumes

NASA Astrophysics Data System (ADS)

Hilgers, Gerhard; Bug, Marion U.; Gargioni, Elisabetta; Rabus, Hans

2015-10-01

The object of investigation in nanodosimetry is the physical characteristics of the microscopic structure of ionising particle tracks, i.e. the sequence of the interaction types and interaction sites of a primary particle and all its secondaries, which reflects the stochastic nature of the radiation interaction. In view of the upcoming radiation therapy with protons and carbon ions, the ionisation structure of the ion track is of particular interest. Owing to limitations in current detector technology, the only way to determine the ionisation cluster size distribution in a DNA segment is to simulate the particle track structure in condensed matter. This is done using dedicated computer programs based on Monte Carlo procedures simulating the interaction of the primary ions with the target. Hence, there is a need to benchmark these computer codes using suitable experimental data. Ionisation cluster size distributions produced in the nanodosimeter's sensitive volume by monoenergetic protons and alpha particles (with energies between 0.1 MeV and 20 MeV) were measured at the PTB ion accelerator facilities. C3H8 and N2 were alternately used as the working gas. The measured data were compared with the simulation results obtained with the PTB Monte-Carlo code PTra [B. Grosswendt, Radiat. Environ. Biophys. 41, 103 (2002); M.U. Bug, E. Gargioni, H. Nettelbeck, W.Y. Baek, G. Hilgers, A.B. Rosenfeld, H. Rabus, Phys. Rev. E 88, 043308 (2013)]. Measured and simulated characteristics of the particle track structure are generally in good agreement for protons over the entire energy range investigated. For alpha particles with energies higher than the Bragg peak energy, a good agreement can also be seen, whereas for energies lower than the Bragg peak energy differences of as much as 25% occur. Significant deviations are only observed for large ionisation cluster sizes. These deviations can be explained by a background consisting of secondary ions. These ions are produced in the region downstream of the extraction aperture by electrons with a kinetic energy of about 2.5 keV, which are themselves released by ions of the "primary" ionisation cluster hitting an electrode in the ion transport system. Including this background of secondary ions in the simulated cluster size distributions leads to a significantly better agreement between measured and simulated data, especially for large ionisation clusters.

The vapour of imidazolium-based ionic liquids: a mass spectrometry study.

PubMed

Deyko, A; Lovelock, K R J; Licence, P; Jones, R G

2011-10-06

Eight common dialkylimidazolium-based ionic liquids have been successfully evaporated in ultra-high vacuum and their vapours analysed by line of sight mass spectrometry using electron ionisation. The ionic liquids investigated were 1-alkyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide, [C(n)C(1)Im][Tf(2)N] (where n = 2, 4, 6, 8), 1-alkyl-3-methylimidazolium tetrafluoroborate, [C(n)C(1)Im][BF(4)] (where n = 4, 8), 1-butyl-3-methylimidazolium octylsulfate, [C(4)C(1)Im][C(8)OSO(3)] and 1-butyl-3-methylimidazolium tetrachloroferrate, [C(4)C(1)Im][FeCl(4)]. All ionic liquids studied here evaporated as neutral ion pairs; no evidence of decomposition products in the vapour phase were observed. Key fragment cations of the ionised vapour of the ionic liquids are identified. The appearance energies, E(app), of the parent cation were measured and used to estimate the ionisation energies, E(i), for the vapour phase neutral ion pairs. Measured ionisation energies ranged from 10.5 eV to 13.0 eV. Using both the identity and E(app) values, the fragmentation pathways for a number of fragment cations are postulated. It will be shown that the enthalpy of vaporisation, Δ(vap)H, can successfully be measured using more than one fragment cation, although caution is required as many fragment cations can also be formed by ionisation of decomposition products.

The vacuum-ultraviolet photoelectron spectra of CH2F2 and CH2Cl2 revisited

NASA Astrophysics Data System (ADS)

Tuckett, Richard; Harvey, Jonelle; Hemberger, Patrick; Bodi, Andras

2015-09-01

The threshold photoelectron spectrum (TPES) of difluoromethane and dichloromethane has been recorded at the Swiss Light Source with a resolution of 2 meV or 16 cm-1. Electronic and vibronic transitions are simulated and assigned with the help of Franck-Condon (FC) calculations based on coupled cluster electronic structure calculations for the equilibrium geometries and harmonic vibrational frequencies of the neutrals, and of the ground and excited electronic states of the cations. Notwithstanding a high-resolution pulsed-field ionisation study on CH2F2 (Forysinski et al., 2010) in which a number of transitions to the X∼+ state have been recorded with unprecedented accuracy, we report the first complete vibrationally resolved overview of the low-lying electronic states of CH2X2+, X = F or Cl. Hydrogen atom loss from CH2F2+ occurs at low energy, making the ground state rather anharmonic and interpretation of the X∼+ band challenging in the harmonic approximation. By Franck-Condon fits, the adiabatic ionisation energies to the A∼+ 2B2, C∼+ 2A2 and D∼+ 2B2 states have been determined as 14.3 ± 0.1, 15.57 ± 0.01 and 18.0 ± 0.1 eV, respectively. The first band in the CH2Cl2 TPES is complex for a different reason, as it is the result of two overlapping ionic states, X∼+ 2B2 and A∼+ 2B1, with derived ionisation energies of 11.0 ± 0.2 and 11.317 ± 0.006 eV, and dominated by an extended progression in the CCl2 bend (in X∼+) and a short progression in the CCl2 symmetric stretch (in A∼+), respectively. Furthermore, even though Koopmans' approximation holds for the vertical ionisations, the X∼+ state of CH2Cl2+ is stabilized by geometry relaxation and corresponds to ionisation from the (HOMO-1) orbital. That is, the first two vertical ionisation energies are in the same order as the negative of the orbital energies of the highest occupied orbitals, but the adiabatic ionisation energy corresponding to electron removal from the (HOMO-1) is lower than the adiabatic ionisation energy corresponding to electron removal from the HOMO. The second band in the spectrum could be analysed to identify the vibrational progressions and determine adiabatic ionisation energies of 12.15 and 12.25 eV for the B∼+ 2A1 and C∼+ 2A2 states. A comparison of the assignment of electronic states with the literature is made difficult by the fact that the B1 and B2 irreducible representations in C2v symmetry depend on the principal plane, i.e. whether the CX2 moiety is in the xz or the yz plane, which is often undefined in older papers.

The interaction of excited atoms and few-cycle laser pulses

PubMed Central

Calvert, J. E.; Xu, Han; Palmer, A. J.; Glover, R. D.; Laban, D. E.; Tong, X. M.; Kheifets, A. S.; Bartschat, K.; Litvinyuk, I. V.; Kielpinski, D.; Sang, R. T.

2016-01-01

This work describes the first observations of the ionisation of neon in a metastable atomic state utilising a strong-field, few-cycle light pulse. We compare the observations to theoretical predictions based on the Ammosov-Delone-Krainov (ADK) theory and a solution to the time-dependent Schrödinger equation (TDSE). The TDSE provides better agreement with the experimental data than the ADK theory. We optically pump the target atomic species and measure the ionisation rate as the a function of different steady-state populations in the fine structure of the target state which shows significant ionisation rate dependence on populations of spin-polarised states. The physical mechanism for this effect is unknown. PMID:27666403

Exploring the Powerful Ionised Wind in the Seyfert Galaxy PG1211+143

NASA Astrophysics Data System (ADS)

Pounds, Ken

2013-10-01

Highly-ionised high-speed winds in AGN (UFOs) were first detected with XMM-Newton a decade ago, and are now established as a key factor in the study of SMBH accretion, and in the growth and metal enrichment of their host galaxies. However, information on the ionisation and dynamical structure, and the ultimate fate of UFOs remains very limited. We request a 600ks extended XMM-Newton study of the prototype UFO PG1211+143 in AO-13, to obtain high quality EPIC and RGS spectra, to map the flow structure and variability, while seeking evidence for the anticipated interaction with the ISM and possible conversion of the energetic wind to a momentum-driven flow.

The interaction of excited atoms and few-cycle laser pulses.

PubMed

Calvert, J E; Xu, Han; Palmer, A J; Glover, R D; Laban, D E; Tong, X M; Kheifets, A S; Bartschat, K; Litvinyuk, I V; Kielpinski, D; Sang, R T

2016-09-26

This work describes the first observations of the ionisation of neon in a metastable atomic state utilising a strong-field, few-cycle light pulse. We compare the observations to theoretical predictions based on the Ammosov-Delone-Krainov (ADK) theory and a solution to the time-dependent Schrödinger equation (TDSE). The TDSE provides better agreement with the experimental data than the ADK theory. We optically pump the target atomic species and measure the ionisation rate as the a function of different steady-state populations in the fine structure of the target state which shows significant ionisation rate dependence on populations of spin-polarised states. The physical mechanism for this effect is unknown.

Electro-optic and radiation damage performance of the CIS115, an imaging sensor for the JANUS optical camera onboard JUICE

NASA Astrophysics Data System (ADS)

Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Stefanov, K.; Pratlong, J.; Leese, M.; Gow, J. P. D.; Smith, D. R.

2016-08-01

The Jupiter Icy Moon Explorer (JUICE) has been officially adopted as the next Large class mission by the European Space Agency, with a launch date of 2022. The science payload includes an optical camera, JANUS, which will perform imaging and mapping observations of Jupiter, its moons and icy rings. A 13 slot filter wheel will be used to provide spectral information in order for the JANUS experiment to study the geology and physical properties of Ganymede, Europa and Io, and to investigate processes and structures in the atmosphere of Jupiter. The sensor selected for JANUS is the back-thinned CIS115, a 3 MPixel CMOS Image Sensor from e2v technologies. The CIS115 has a 4-Transistor pixel design with a pinned photodiode to improve signal to noise performance by reducing dark current and allowing for reset level subtraction. The JUICE mission will consist of an 8 year cruise phase followed by a 3 year science phase in the Jovian system. Models of the radiation environment throughout the JUICE mission predict that the End of Life (EOL) non-ionising damage will be equivalent to 1010 protons cm-2 (10 MeV) and the EOL ionising dose will be 100 krad(Si), once the shielding from the spacecraft and instrument design is taken into account. An extensive radiation campaign is therefore being carried out to qualify and characterise the CIS115 for JANUS, as well as other space and terrestrial applications. Radiation testing to take the CIS115 to twice the ionising dose and displacement damage levels was completed in 2015 and the change in sensor performance has been characterised. Good sensor performance has been observed following irradiation and a summary of the key results from the campaign using gamma irradiation (ionising dose) will be presented here, including its soft X-ray detection capabilities, flat-band voltage shift and readout noise. In 2016, further radiation campaigns on flight-representative CIS115s will be undertaken and their results will be disseminated in future publications.

The Influence of the Solar Coronal Radiation on Coronal Plasma Structures, I: Determination of the Incident Coronal Radiation

NASA Astrophysics Data System (ADS)

Brown, Gerrard M.; Labrosse, Nicolas

2018-02-01

Coronal structures receive radiation not only from the solar disc, but also from the corona. This height-dependent incident radiation plays a crucial role in the excitation and the ionisation of the illuminated plasma. The aim of this article is to present a method for computing the detailed incident radiation coming from the solar corona, which is perceived at a point located at an arbitrary height. The coronal radiation is calculated by integrating the radiation received at a point in the corona over all of the corona visible from this point. The emission from the corona at all wavelengths of interest is computed using atomic data provided by CHIANTI. We obtain the spectrum illuminating points located at varying heights in the corona at wavelengths between 100 and 912 Å when photons can ionise H or He atoms and ions in their ground states. As expected, individual spectral lines will contribute most at the height within the corona where the local temperature is closest to their formation temperature. As there are many spectral lines produced by many ions, the coronal intensity cannot be assumed to vary in the same way at all wavelengths and so must be calculated for each separate height that is to be considered. This code can be used to compute the spectrum from the corona illuminating a point at any given height above the solar surface. This brings a necessary improvement to models where an accurate determination of the excitation and ionisation states of coronal plasma structures is crucial.

Ambient ionisation mass spectrometry for in situ analysis of intact proteins

PubMed Central

Kocurek, Klaudia I.; Griffiths, Rian L.

2018-01-01

Abstract Ambient surface mass spectrometry is an emerging field which shows great promise for the analysis of biomolecules directly from their biological substrate. In this article, we describe ambient ionisation mass spectrometry techniques for the in situ analysis of intact proteins. As a broad approach, the analysis of intact proteins offers unique advantages for the determination of primary sequence variations and posttranslational modifications, as well as interrogation of tertiary and quaternary structure and protein‐protein/ligand interactions. In situ analysis of intact proteins offers the potential to couple these advantages with information relating to their biological environment, for example, their spatial distributions within healthy and diseased tissues. Here, we describe the techniques most commonly applied to in situ protein analysis (liquid extraction surface analysis, continuous flow liquid microjunction surface sampling, nano desorption electrospray ionisation, and desorption electrospray ionisation), their advantages, and limitations and describe their applications to date. We also discuss the incorporation of ion mobility spectrometry techniques (high field asymmetric waveform ion mobility spectrometry and travelling wave ion mobility spectrometry) into ambient workflows. Finally, future directions for the field are discussed. PMID:29607564

Matrix-free mass spectrometric imaging using laser desorption ionisation Fourier transform ion cyclotron resonance mass spectrometry

PubMed Central

Goodwin, Richard J A; Pitt, Andrew R; Harrison, David; Weidt, Stefan K; Langridge-Smith, Pat R R; Barrett, Michael P; Logan Mackay, C

2011-01-01

Mass spectrometry imaging (MSI) is a powerful tool in metabolomics and proteomics for the spatial localization and identification of pharmaceuticals, metabolites, lipids, peptides and proteins in biological tissues. However, sample preparation remains a crucial variable in obtaining the most accurate distributions. Common washing steps used to remove salts, and solvent-based matrix application, allow analyte spreading to occur. Solvent-free matrix applications can reduce this risk, but increase the possibility of ionisation bias due to matrix adhesion to tissue sections. We report here the use of matrix-free MSI using laser desorption ionisation performed on a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. We used unprocessed tissue with no post-processing following thaw-mounting on matrix-assisted laser desorption ionisation (MALDI) indium-tin oxide (ITO) target plates. The identification and distribution of a range of phospholipids in mouse brain and kidney sections are presented and compared with previously published MALDI time-of-flight (TOF) MSI distributions. Copyright © 2011 John Wiley & Sons, Ltd. PMID:21416534

Ambient ionisation mass spectrometry for the characterisation of polymers and polymer additives: a review.

PubMed

Paine, Martin R L; Barker, Philip J; Blanksby, Stephen J

2014-01-15

The purpose of this review is to showcase the present capabilities of ambient sampling and ionisation technologies for the analysis of polymers and polymer additives by mass spectrometry (MS) while simultaneously highlighting their advantages and limitations in a critical fashion. To qualify as an ambient ionisation technique, the method must be able to probe the surface of solid or liquid samples while operating in an open environment, allowing a variety of sample sizes, shapes, and substrate materials to be analysed. The main sections of this review will be guided by the underlying principle governing the desorption/extraction step of the analysis; liquid extraction, laser ablation, or thermal desorption, and the major component investigated, either the polymer itself or exogenous compounds (additives and contaminants) present within or on the polymer substrate. The review will conclude by summarising some of the challenges these technologies still face and possible directions that would further enhance the utility of ambient ionisation mass spectrometry as a tool for polymer analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

Medical student knowledge regarding radiology before and after a radiological anatomy module: implications for vertical integration and self-directed learning.

PubMed

Murphy, Kevin P; Crush, Lee; O'Malley, Eoin; Daly, Fergus E; O'Tuathaigh, Colm M P; O'Connor, Owen J; Cryan, John F; Maher, Michael M

2014-10-01

To examine the impact that anatomy-focused radiology teaching has on non-examined knowledge regarding radiation safety and radiology as a specialty. First-year undergraduate medical students completed surveys prior to and after undertaking the first-year anatomy programme that incorporates radiological anatomy. Students were asked opinions on preferred learning methodology and tested on understanding of radiology as a specialty and radiation safety. Pre-module and post-module response rates were 93 % (157/168) and 85 % (136/160), respectively. Pre-module and post-module, self-directed learning (SDL) ranked eighth (of 11) for preferred gross-anatomy teaching formats. Correct responses regarding radiologist/radiographer roles varied from 28-94 % on 16 questions with 4/16 significantly improving post-module. Identification of modalities that utilise radiation significantly improved for five of eight modalities post-module but knowledge regarding relative amount of modality-specific radiation use was variable pre-module and post-module. SDL is not favoured as an anatomy teaching method. Exposure of students to a radiological anatomy module delivered by senior clinical radiologists improved basic knowledge regarding ionising radiation use, but there was no improvement in knowledge regarding radiation exposure relative per modality. A possible explanation is that students recall knowledge imparted in didactic lectures but do little reading around the subject when the content is not examined. • Self-directed learning is not favoured as a gross anatomy teaching format amongst medical students. • An imaging anatomy-focused module improved basic knowledge regarding ionising radiation use. • Detailed knowledge of modality-specific radiation exposure remained suboptimal post-module. • Knowledge of roles within a clinical radiology department showed little change post-module.

Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

PubMed

Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

2017-04-01

Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

A miniaturised laser ablation/ionisation analyser for investigation of elemental/isotopic composition with the sub-ppm detection sensitivity

NASA Astrophysics Data System (ADS)

Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

2012-04-01

Detailed knowledge of the elemental and isotopic composition of solar system objects imposes critical constraints on models describing the origin of our solar system and can provide insight to chemical and physical processes taking place during the planetary evolution. So far, the investigation of chemical composition of planetary surfaces could be conducted almost exclusively by remotely controlled spectroscopic instruments from orbiting spacecraft, landers or rovers. With some exceptions, the sensitivity of these techniques is, however, limited and often only abundant elements can be investigated. Nevertheless, the spectroscopic techniques proved to be successful for global chemical mapping of entire planetary objects such as the Moon, Mars and asteroids. A combined afford of the measurements from orbit, landers and rovers can also yield the determination of local mineralogy. New instruments including Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation/Ionisation Mass Spectrometer (LIMS), have been recently included for several landed missions. LIBS is thought to improve flexibility of the investigations and offers a well localised chemical probing from distances up to 10-13 m. Since LIMS is a mass spectrometric technique it allows for very sensitive measurements of elements and isotopes. We will demonstrate the results of the current performance tests obtained by application of a miniaturised laser ablation/ionisation mass spectrometer, a LIMS instrument, developed in Bern for the chemical analysis of solids. So far, the only LIMS instrument on a spacecraft is the LAZMA instrument. This spectrometer was a part of the payload for PHOBOS-GRUNT mission and is also currently selected for LUNA-RESURCE and LUNA-GLOB missions to the lunar south poles (Managadze et al., 2011). Our LIMS instrument has the dimensions of 120 x Ø60 mm and with a weight of about 1.5 kg (all electronics included), it is the lightest mass analyser designed for in situ chemical analysis of solid materials on the planetary surfaces (Rohner et al., 2003). Initial laboratory tests that were conducted with an IR laser radiation for the ablation, atomisation and ionisation of the material, indicated a high performance of the instrument in terms of sensitivity, dynamic range and mass resolution (Tulej et al., 2011). After some technical improvements and implementation of a computer-controlled performance optimiser we have achieved further improvements of both, the instrumental sensitivity down to sub-ppm level and reproducibility of the measurements. We will demonstrate the potential of the mass analyser to perform the quantitative elemental analysis of solids with a spatial (vertical, lateral) resolution commensurate with typical grain sizes, and its capabilities for investigation of isotopic patterns with accuracy and precision comparable to that of large analytical laboratory instruments, e.g., TIMS, SIMS, LA-ICP-MS. The results can be of considerable interest for in situ dating or investigation of other fine isotopic fractionation effects including studies of bio-markers.

The potential of organic (electrospray- and atmospheric pressure chemical ionisation) mass spectrometric techniques coupled to liquid-phase separation for speciation analysis.

PubMed

Rosenberg, Erwin

2003-06-06

The use of mass spectrometry based on atmospheric pressure ionisation techniques (atmospheric pressure chemical ionisation, APCI, and electrospray ionisation, ESI) for speciation analysis is reviewed with emphasis on the literature published in and after 1999. This report accounts for the increasing interest that atmospheric pressure ionisation techniques, and in particular ESI, have found in the past years for qualitative and quantitative speciation analysis. In contrast to element-selective detectors, organic mass spectrometric techniques provide information on the intact metal species which can be used for the identification of unknown species (particularly with MS-MS detection) or the confirmation of the actual presence of species in a given sample. Due to the complexity of real samples, it is inevitable in all but the simplest cases to couple atmospheric pressure MS detection to a separation technique. Separation in the liquid phase (capillary electrophoresis or liquid chromatography in reversed phase, ion chromatographic or size-exclusion mode) is particularly suitable since the available techniques cover a very wide range of analyte polarities and molecular mass. Moreover, derivatisation can normally be avoided in liquid-phase separation. Particularly in complex environmental or biological samples, separation in one dimension is not sufficient for obtaining adequate resolution for all relevant species. In this case, multi-dimensional separation, based on orthogonal separation techniques, has proven successful. ESI-MS is also often used in parallel with inductively coupled plasma MS detection. This review is structured in two parts. In the first, the fundamentals of atmospheric pressure ionisation techniques are briefly reviewed. The second part of the review discusses recent applications including redox species, use of ESI-MS for structural elucidation of metal complexes, characterisation and quantification of small organometallic species with relevance to environment, health and food. Particular attention is given to the characterisation of biomolecules and metalloproteins (metallothioneins and phytochelatins) and to the investigation of the interaction of metals and biomolecules. Particularly in the latter field, ESI-MS is the ideal technique due to the softness of the ionisation process which allows to assume that the detected gas-phase ions are a true representation of the ions or ion-biomolecule complexes prevalent in solution. It is particularly this field, important to biochemistry, physiology and medical chemistry, where we can expect significant developments also in the future.

Simulation of the radiolysis of water using Green's functions of the diffusion equation.

PubMed

Plante, I; Cucinotta, F A

2015-09-01

Radiation chemistry is of fundamental importance in the understanding of the effects of ionising radiation, notably with regard to DNA damage by indirect effect (e.g. damage by ·OH radicals created by the radiolysis of water). In the recent years, Green's functions of the diffusion equation (GFDEs) have been used extensively in biochemistry, notably to simulate biochemical networks in time and space. In the present work, an approach based on the GFDE will be used to refine existing models on the indirect effect of ionising radiation on DNA. As a starting point, the code RITRACKS (relativistic ion tracks) will be used to simulate the radiation track structure and calculate the position of all radiolytic species formed during irradiation. The chemical reactions between these radiolytic species and with DNA will be done by using an efficient Monte Carlo sampling algorithm for the GFDE of reversible reactions with an intermediate state that has been developed recently. These simulations should help the understanding of the contribution of the indirect effect in the formation of DNA damage, particularly with regards to the formation of double-strand breaks. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Examining Pre-Service Teachers' Use of Atomic Models in Explaining Subsequent Ionisation Energy Values

ERIC Educational Resources Information Center

Wheeldon, Ruth

2012-01-01

Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in "J Chem Educ" 86(5):623-629, 2009). This research extends this work by…

Search for ionisation density effects in the radiation absorption stage in LiF:Mg,Ti.

PubMed

Nail, I; Horowitz, Y S; Oster, L; Brandan, M E; Rodríguez-Villafuerte, M; Buenfil, A E; Ruiz-Trejo, C; Gamboa-Debuen, I; Avila, O; Tovar, V M; Olko, P; Ipe, N

2006-01-01

Optical absorption (OA) dose-response of LiF:Mg,Ti (TLD-100) is studied as a function of electron energy (ionisation density) and irradiation dose. Contrary to the situation in thermoluminescence dose-response where the supralinearity is strongly energy-dependent, no dependence of the OA dose filling constants on energy is observed. This result is interpreted as indicating a lack of competitive process in the radiation absorption stage. The lack of an energy dependence of the dose filling constant also suggests that the charge carrier migration distances are sufficiently large to smear out the differences in the non-uniform distribution of ionisation events created by the impinging gamma/electron radiation of various energies.

Further investigations of the effect of pressure on retention in ultra-high-pressure liquid chromatography.

PubMed

Fallas, Morgane M; Neue, Uwe D; Hadley, Mark R; McCalley, David V

2010-01-15

In this study, we investigated further the large increases in retention with pressure that we observed previously in RP-LC especially for ionised solutes. These findings were initially confirmed on a conventional silica C(18) column, which gave extremely similar results to the hybrid C(18) phase originally used. Large increases in retention factor of approximately 50% for a pressure increase of 500 bar were also shown for high MW polar but neutral solutes. However, experiments with the same bases in ionised and non-ionised forms suggest that somewhat greater pressure-induced retention increases are found for ionised solutes. Retention increases with pressure were found to be considerably smaller for a C(1) column compared with a C(18) column; decreases in retention with increasing pressure were noted for ionised bases when using a bare silica column in the hydrophilic interaction chromatography (HILIC) mode. These observations are consistent with the partial loss of the solvation layer in RP-LC as the solute is forced into the hydrophobic environment of the stationary phase, and consequent reduction in the solute molar volume, while the water layer on the surface of a HILIC packing increases the hydration of a basic analyte. Finally, retention changes with pressure in RP-LC can also be observed at a mobile phase pH close to the solute pK(a), due to changes in pK(a) with pressure. However, this effect has no influence on the results of most of our studies. 2009 Elsevier B.V. All rights reserved.

Radiation Effects on LWS Detectors and Deglitching of LWS Data

NASA Astrophysics Data System (ADS)

Burgdorf, M.; Harwood, A.; Sidher, S. D.

Glitches are caused by the effects of ionising particles (either a primary cosmic ray, interplanetary or belt electron, or a secondary generated in the spacecraft structure) on the detectors. There was roughly one glitch per ten seconds per detector during the normal period of LWS operation. These energetic particles cause a sudden jump in the ramp voltage, due to a quantity of charge being dumped on the integrating amplifier. They also cause a change in the detector responsivity which affects the following ramps. Glitches were detected in the automatic pipeline processing for each observation with the LWS that was performed with a standard Astronomical Observation Template. We describe the method with which this deglitching was carried out. Based on the findings from the deglitching algorithms we compare proton and electron fluences with average glitch rates and look for correlations. >From the glitch statistics one can also derive the energy distribution of the ionising radiation that hit the detectors. This energy spectrum agrees roughly with model predictions and therefore shows that it is in principle possible to predict the properties of the ionising radiation to which the detectors of future missions will be exposed. This is important, because for the LWS we found that the effect of an ionising radiation hit on the detectors was rather different, and more severe, than had been predicted before launch: An ionising particle could cause the detector to become unstable and spike spontaneously for some seconds following a hit, resulting in a strongly increased noise and requiring a re-adjustment of the bias levels.

Exploring Learners' Conceptual Resources: Singapore a Level Students' Explanations in the Topic of Ionisation Energy

ERIC Educational Resources Information Center

Taber, Keith S.; Tan, Kim Chwee Daniel

2007-01-01

This paper describes findings from a study to explore Singapore A-level (Grades 11 and 12, 16-19 yr old) students' understanding of ionisation energy, an abstract and complex topic that is featured in school chemistry courses. Previous research had reported that students in the United Kingdom commonly use alternative notions based on the perceived…

Characterisation of semi-insulating GaAs

NASA Technical Reports Server (NTRS)

Walukiewicz, W.; Pawlowicz, L.; Lagowski, J.; Gatos, H. C.

1982-01-01

Hole and electron mobilities as functions of temperature and ionised impurity concentration are calculated for GaAs. It is shown that these calculations, when used to analyse electrical properties of semi-insulating GaAs, enable an assessment of the Fermi energy position and ionised impurity concentration to be made. In contrast to previous work, the analysis does not require any phenomenological assumptions.

An improved experimental scheme for simultaneous measurement of high-resolution zero electron kinetic energy (ZEKE) photoelectron and threshold photoion (MATI) spectra

NASA Astrophysics Data System (ADS)

Michels, François; Mazzoni, Federico; Becucci, Maurizio; Müller-Dethlefs, Klaus

2017-10-01

An improved detection scheme is presented for threshold ionization spectroscopy with simultaneous recording of the Zero Electron Kinetic Energy (ZEKE) and Mass Analysed Threshold Ionisation (MATI) signals. The objective is to obtain accurate dissociation energies for larger molecular clusters by simultaneously detecting the fragment and parent ion MATI signals with identical transmission. The scheme preserves an optimal ZEKE spectral resolution together with excellent separation of the spontaneous ion and MATI signals in the time-of-flight mass spectrum. The resulting improvement in sensitivity will allow for the determination of dissociation energies in clusters with substantial mass difference between parent and daughter ions.

Airborne laser-spark for ambient desorption/ionisation.

PubMed

Bierstedt, Andreas; Riedel, Jens

A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die Desorption als auch die Ionisation erfolgen hierbei durch ein laserbetriebenes Luftplasma. Die Abwesenheit fester oder flüssiger Elektroden hat zur Folge, dass die Methode weder unter chemischen Interferenzen noch unter Verschleiß durch Korrosionsbrand oder abgetragenes Elektrodenmaterial leidet. Insgesamt betrachtet herrscht in dem Plasma Elektroneutralität, wodurch Aufladungseffekte minimiert werden, die andernfalls zu einer langfristigenÄderung der Flugbahnen von Ionen während der Experimente führen kann. In dem Ansatz eine freischwebende Luftentladung bei Atmosphärendruck zu verwenden agiert die Luft nicht nur als Plasmamedium sondert dient zusätzlich als Badgas für die stoßinduzierte Kühlung der entstehenden Ionen. Die Ionisierung der Analytmoleküle erfolgt nicht unmittelbar im Plasma sondern in dessen direkter Umgebung durch Wechselwirkung mit freigesetzten ionischen Luftspezies, freien Elektronen oder Photonen im kurzwelligen ultravioletten Bereich. Jede Laserentladung erzeugt eine hörbare Stoßwelle, in welcher neu produzierte reaktive Spezies freigesetzt werden, welche sich konzentrisch ausbreiten, so dass eine Diffusion der Analytmoleküle ins heiße Innere des Plasmas verhindert wird. Daraus folgt, dass im Interaktionsvolumen zwischen Plasma und Analyt der Temperaturgrenzwert für eine thermische Dissoziation oder Fragmentierung der Moleküle nicht überschritten wird. Experimentell konnte belegt werden, dass das vorgestellte Ionisierungsschema sehr unselektiv bezüglich der chemischen Analytklasse ist und kaum Fragmentierungsprodukte beobachtet werden können. Messungen einer breitgefächerten Auswahl unterschiedlicher Testsubstanzen, wie beispielsweise polarer und unpolarer Kohlenwasserstoffe, Zuckern, niedermolekularer pharmazeutischer Wirkstoffe, sowie natürlicher Biomoleküle in Lebensmittelproben unmittelbar aus ihren komplexen Matrizes, führten zu aussagekräftigen Massenspektren. Zumal das Lasermedium feuchte Luft ist, scheint der Reaktionsmechanismus dem anderer Atmosphärendruckionisierungsmethoden zuähneln.

An X-Ray/SDSS Sample: Observational Characterization of The Outflowing Gas

NASA Astrophysics Data System (ADS)

Perna, Michele; Brusa, M.; Lanzuisi, G.; Mignoli, M.

2016-10-01

Powerful ionised AGN-driven outflows, commonly detected both locally and at high redshift, are invoked to contribute to the co-evolution of SMBH and galaxies through feedback phenomena. Our recent works (Brusa+2015; 2016; Perna+2015a,b) have shown that the XMM-COSMOS targets with evidence of outflows collected so far ( 10 sources) appear to be associated with low X-ray kbol corrections (Lbol /LX ˜ 18), in spite of their spread in obscuration, in the locations on the SFR-Mstar diagram, in their radio emission. A higher statistical significance is required to validate a connection between outflow phenomena and a X-ray loudness. Moreover, in order to validate their binding nature to the galaxy fate, it is crucial to correctly determine the outflow energetics. This requires time consuming integral field spectroscopic (IFS) observations, which are, at present, mostly limited to high luminosity objectsThe study of SDSS data offers a complementary strategy to IFS efforts. I will present physical and demographic characterization of the AGN-galaxy system during the feedback phase obtained studying a sample of 500 X-ray/SDSS AGNs, at z<0.8. Outflow velocity inferred from [OIII]5007 emission line profile has been related to optical (e.g., [OIII] and bolometric luminosities, Eddington ratio, stellar velocity dispersion) and X-ray properties (intrinsic X-ray luminosity, obscuration and X-ray kbol correction), to determine what drives ionised winds. Several diagnostic line ratios have been used to infer the physical properties of the ionised outflowing gas. The knowledge of these properties can reduce the actual uncertainties in the outflow energetics by a factor of ten, pointing to improve our understanding of the AGN outflow phenomenon and its impact on galaxy evolution.

Ullage Tank Fuel-Air Mixture Characterisation

DTIC Science & Technology

2011-12-01

247-252 Woodrow, J.E., Seiber, J.N., 1988, ‘Vapor-pressure measurement of complex mixtures by headspace gas chromatography ’, Journal of...Electron Ionisation FAR Fuel to Air Mass Ratio FID Flame Ionisation Detector GC Gas Chromatography HS Headspace MS Mass Spectrometry NIST...Determination of volatile substances in biological headspace gas chromatography ’, Journal of Chromatography A, vol. 674, pp. 25-62 Shepherd, J.E, Krok, J.C

Temporally separating Cherenkov radiation in a scintillator probe exposed to a pulsed X-ray beam.

PubMed

Archer, James; Madden, Levi; Li, Enbang; Carolan, Martin; Petasecca, Marco; Metcalfe, Peter; Rosenfeld, Anatoly

2017-10-01

Cherenkov radiation is generated in optical systems exposed to ionising radiation. In water or plastic devices, if the incident radiation has components with high enough energy (for example, electrons or positrons with energy greater than 175keV), Cherenkov radiation will be generated. A scintillator dosimeter that collects optical light, guided by optical fibre, will have Cherenkov radiation generated throughout the length of fibre exposed to the radiation field and compromise the signal. We present a novel algorithm to separate Cherenkov radiation signal that requires only a single probe, provided the radiation source is pulsed, such as a linear accelerator in external beam radiation therapy. We use a slow scintillator (BC-444) that, in a constant beam of radiation, reaches peak light output after 1 microsecond, while the Cherenkov signal is detected nearly instantly. This allows our algorithm to separate the scintillator signal from the Cherenkov signal. The relative beam profile and depth dose of a linear accelerator 6MV X-ray field were reconstructed using the algorithm. The optimisation method improved the fit to the ionisation chamber data and improved the reliability of the measurements. The algorithm was able to remove 74% of the Cherenkov light, at the expense of only 1.5% scintillation light. Further characterisation of the Cherenkov radiation signal has the potential to improve the results and allow this method to be used as a simpler optical fibre dosimeter for quality assurance in external beam therapy. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Potential errors in relative dose measurements in kilovoltage photon beams due to polarity effects in plane-parallel ionisation chambers

NASA Astrophysics Data System (ADS)

Dowdell, S.; Tyler, M.; McNamara, J.; Sloan, K.; Ceylan, A.; Rinks, A.

2016-12-01

Plane-parallel ionisation chambers are regularly used to conduct relative dosimetry measurements for therapeutic kilovoltage beams during commissioning and routine quality assurance. This paper presents the first quantification of the polarity effect in kilovoltage photon beams for two types of commercially available plane-parallel ionisation chambers used for such measurements. Measurements were performed at various depths along the central axis in a solid water phantom and for different field sizes at 2 cm depth to determine the polarity effect for PTW Advanced Markus and Roos ionisation chambers (PTW-Freiburg, Germany). Data was acquired for kilovoltage beams between 100 kVp (half-value layer (HVL)  =  2.88 mm Al) and 250 kVp (HVL  =  2.12 mm Cu) and field sizes of 3-15 cm diameter for 30 cm focus-source distance (FSD) and 4  ×  4 cm2-20  ×  20 cm2 for 50 cm FSD. Substantial polarity effects, up to 9.6%, were observed for the Advanced Markus chamber compared to a maximum 0.5% for the Roos chamber. The magnitude of the polarity effect was observed to increase with field size and beam energy but was consistent with depth. The polarity effect is directly influenced by chamber design, with potentially large polarity effects for some plane-parallel ionisation chambers. Depending on the specific chamber used, polarity corrections may be required for output factor measurements of kilovoltage photon beams. Failure to account for polarity effects could lead to an incorrect dose being delivered to the patient.

Do nuisance alarms decrease functionality of smoke alarms near the kitchen? Findings from a randomised controlled trial.

PubMed

Yang, Jingzhen; Jones, Michael P; Cheng, Gang; Ramirez, Marizen; Taylor, Craig; Peek-Asa, Corinne

2011-06-01

Many home fires begin in the kitchen. Kitchen smoke alarms are more likely to produce nuisance alarms, but few previous studies have examined the role of alarm sensor and battery types on the functionality of smoke alarms located nearest to the kitchen. Data were analysed from a 2×2 factorial randomised controlled trial conducted in rural Iowa homes (n=628). Enrolled households were randomly assigned into one of four smoke alarm/battery combinations: ionisation/zinc, ionisation/lithium, photoelectric/zinc and photoelectric/lithium. Alarm functionality was determined using a smoke test. Alarm type and battery type were compared using an intent-to-treat analysis. Logistic regression was used to identify factors that might impact the functionality of smoke alarms located nearest to the kitchen 42 months after installation. Photoelectric alarms with lithium batteries had the highest rate of functionality (90.2%), whereas ionisation alarms with carbon/zinc batteries had the lowest (76.5%). Forty-two months following installation, 6.4% more of photoelectric alarms were functional than ionisation alarms, and 7.9% more of alarms with lithium batteries were functional than those with carbon/zinc batteries. Logistic regression revealed that when the indicator of nuisance alarms was included, the effect of alarm type became statistically insignificant and ionisation alarms were less likely to be functional at 42 months, partly due to increased nuisance alarms. Alarm type is an important consideration for certain locations. Photoelectric alarms may be more appropriate for installation nearest to the kitchen despite their increased cost. These findings can help guide consumer choices to increase protection against home fire-related injuries and deaths.

Full Ionisation In Binary-Binary Encounters With Small Positive Energies

NASA Astrophysics Data System (ADS)

Sweatman, W. L.

2006-08-01

Interactions between binary stars and single stars and binary stars and other binary stars play a key role in the dynamics of a dense stellar system. Energy can be transferred between the internal dynamics of a binary and the larger scale dynamics of the interacting objects. Binaries can be destroyed and created by the interaction. In a binary-binary encounter, full ionisation occurs when both of the binary stars are destroyed in the interaction to create four single stars. This is only possible when the total energy of the system is positive. For very small energies the probability of this occurring is very low and it tends towards zero as the total energy tends towards zero. Here the case is considered for which all the stars have equal masses. An asymptotic power law is predicted relating the probability of full ionisation with the total energy when this latter quantity is small. The exponent, which is approximately 2.31, is compared with the results from numerical scattering experiments. The theoretical approach taken is similar to one used previously in the three-body problem. It makes use of the fact that the most dramatic changes in scale and energies of a few-body system occur when its components pass near to a central configuration. The position, and number, of these configurations is not known for the general four-body problem, however, with equal masses there are known to be exactly five different cases. Separate consideration and comparison of the properties of orbits close to each of these five central configurations enables the prediction of the form of the cross-section for full ionisation for the case of small positive total energy. This is the relation between total energy and the probability of total ionisation described above.

Occupational exposure to ionising radiation and mortality among workers of the former Spanish Nuclear Energy Board.

PubMed Central

Rodríguez Artalejo, F; Castaño Lara, S; de Andrés Manzano, B; García Ferruelo, M; Iglesias Martín, L; Calero, J R

1997-01-01

OBJECTIVES: Firstly, to ascertain whether mortality among workers of the former Spanish Nuclear Energy Board (Junta de Energía Nuclear-JEN) was higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated with exposure to ionising radiation. METHODS: A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Cohort mortality was compared with that for the Spanish population overall, with standardised mortality ratios (SMRs) adjusted for sex, age, and calendar period. Also, Poisson models were used to analyse mortality from lung cancer in the cohort by level of exposure to ionising radiation. RESULTS: Workers' median and mean cumulative exposures were 4.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (six deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant respiratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radiation in the dose quartiles 2, 3, and 4 versus the lowest dose quartile, were 1.00, 1.64, and 0.94, respectively. CONCLUSIONS: Excess mortality from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exposure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours. PMID:9155782

Fully kinetic simulations of magnetic reconnection in partially ionised gases

NASA Astrophysics Data System (ADS)

Innocenti, M. E.; Jiang, W.; Lapenta, G.; Markidis, S.

2016-12-01

Magnetic reconnection has been explored for decades as a way to convert magnetic energy into kinetic energy and heat and to accelerate particles in environments as different as the solar surface, planetary magnetospheres, the solar wind, accretion disks, laboratory plasmas. When studying reconnection via simulations, it is usually assumed that the plasma is fully ionised, as it is indeed the case in many of the above-mentioned cases. There are, however, exceptions, the most notable being the lower solar atmosphere. Small ionisation fractions are registered also in the warm neutral interstellar medium, in dense interstellar clouds, in protostellar and protoplanetary accreditation disks, in tokamak edge plasmas and in ad-hoc laboratory experiments [1]. We study here how magnetic reconnection is modified by the presence of a neutral background, i.e. when the majority of the gas is not ionised. The ionised plasma is simulated with the fully kinetic Particle-In-Cell (PIC) code iPic3D [2]. Collisions with the neutral background are introduced via a Monte Carlo plug-in. The standard Monte Carlo procedure [3] is employed to account for elastic, excitation and ionization electron-neutral collisions, as well as for elastic scattering and charge exchange ion-neutral collisions. Collisions with the background introduce resistivity in an otherwise collisionless plasma and modifications of the particle distribution functions: particles (and ions at a faster rate) tend to thermalise to the background. To pinpoint the consequences of this, we compare reconnection simulations with and without background. References [1] E E Lawrence et al. Physical review letters, 110(1):015001, 2013. [2] S Markidis et al. Mathematics and Computers in Simulation, 80(7):1509-1519, 2010. [3] K Nanbu. IEEE Transactions on plasma science, 28(3):971-990, 2000.

Occupational exposure to ionising radiation and mortality among workers of the former Spanish Nuclear Energy Board.

PubMed

Rodríguez Artalejo, F; Castaño Lara, S; de Andrés Manzano, B; García Ferruelo, M; Iglesias Martín, L; Calero, J R

1997-03-01

Firstly, to ascertain whether mortality among workers of the former Spanish Nuclear Energy Board (Junta de Energía Nuclear-JEN) was higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated with exposure to ionising radiation. A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Cohort mortality was compared with that for the Spanish population overall, with standardised mortality ratios (SMRs) adjusted for sex, age, and calendar period. Also, Poisson models were used to analyse mortality from lung cancer in the cohort by level of exposure to ionising radiation. Workers' median and mean cumulative exposures were 4.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (six deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant respiratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radiation in the dose quartiles 2, 3, and 4 versus the lowest dose quartile, were 1.00, 1.64, and 0.94, respectively. Excess mortality from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exposure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours.

The nature of the ionised nebula surrounding the red supergiant W26

NASA Astrophysics Data System (ADS)

Wesson, Roger

2015-08-01

The red supergiant W26 in the massive star cluster Westerlund 1 is surrounded by a compact ionised nebula. This is unique among RSGs, and the excitation mechanism of the nebula is not yet known - it may be ionised by an unseen compact companion, or by a nearby blue supergiant. We present new observations of the nebula: high resolution spatially resolved spectra taken with FLAMES at the VLT show that the nebula is a ring, with velocities consistent with that expected for red supergiant ejecta, and ruling out the possibility of a Luminous Blue Variable-type eruption preceding the RSG phase as the origin of the nebula. A triangular patch of nebulosity outside the ring appears to be associated with W26, and may be material stripped from the expanding ring by the cumulative cluster wind and radiation field.

Distinct EUV minimum of the solar irradiance (16-40 nm) observed by SolACES spectrometers onboard the International Space Station (ISS) in August/September 2009

NASA Astrophysics Data System (ADS)

Nikutowski, B.; Brunner, R.; Erhardt, Ch.; Knecht, St.; Schmidtke, G.

2011-09-01

In the field of terrestrial climatology the continuous monitoring of the solar irradiance with highest possible accuracy is an important goal. SolACES as a part of the ESA mission SOLAR on the ISS is measuring the short-wavelength solar EUV irradiance from 16-150 nm. This data will be made available to the scientific community to investigate the impact of the solar irradiance variability on the Earth's climate as well as the thermospheric/ionospheric interactions that are pursued in the TIGER program. Since the successful launch with the shuttle mission STS-122 on February 7th, 2008, SolACES initially recorded the low EUV irradiance during the extended solar activity minimum. Thereafter it has been observing the EUV irradiance during the increasing solar activity with enhanced intensity and changing spectral composition. SolACES consists of three grazing incidence planar grating spectrometers. In addition there are two three-signal ionisation chambers, each with exchangeable band-pass filters to determine the absolute EUV fluxes repeatedly during the mission. One important problem of space-borne instrumentation recording the solar EUV irradiance is the degradation of the spectrometer sensitivity. The two double ionisation chambers of SolACES, which could be re-filled with three different gases for each recording, allow the recalibration of the efficiencies of the three SolACES spectrometers from time to time.

A liquid chromatography/electrospray ionisation tandem mass spectrometry method for the simultaneous quantification of salicylic, jasmonic and abscisic acids in Coffea arabica leaves.

PubMed

de Sá, Marta; Ferreira, João P; Queiroz, Vagner T; Vilas-Boas, Luís; Silva, Maria C; Almeida, Maria H; Guerra-Guimarães, Leonor; Bronze, Maria R

2014-02-01

Plants have developed an efficient system of recognition that induces a complex network of signalling molecules such as salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA) in case of a pathogenic infection. The use of specific and sensitive methods is mandatory for the analysis of compounds in these complex samples. In this study a liquid chromatography/electrospray ionisation tandem mass spectrometry method was developed and validated for the simultaneous quantification of SA, JA and ABA in Coffea arabica (L.) leaves in order to understand the role of these phytohormones in the signalling network involved in the coffee defence response against Hemileia vastatrix. The results showed that the method was specific, linear (r ≥ 0.99) in the range 0.125-1.00 µg mL⁻¹ for JA and ABA and 0.125-5.00 µg mL⁻¹ for SA, and precise (relative standard deviation ≤11%), and the limit of detection (0.010 µg g⁻¹ fresh weight) was adequate for quantifying these phytohormones in this type of matrix. In comparison with healthy leaves, those infected with H. vastatrix (resistance reaction) displayed an increase in SA level 24 h after inoculation, suggesting the involvement of an SA-dependent pathway in coffee resistance. © 2013 Society of Chemical Industry.

The Insidious Nature of "Hard-Core" Alternative Conceptions: Implications for the Constructivist Research Programme of Patterns in High School Students' and Pre-Service Teachers' Thinking about Ionisation Energy

ERIC Educational Resources Information Center

Taber, Keith S.; Tan, Kim Chwee Daniel

2011-01-01

The present study contributes to the constructivist research programme (RP) into learning science by comparing patterns in responses from two groups of learners--senior high school students and pre-service teachers--in the same educational context (Singapore), to a diagnostic instrument relating to the topic of ionisation energies. This topic is…

Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry.

PubMed

Mämmelä, P; Savolainen, H; Lindroos, L; Kangas, J; Vartiainen, T

2000-09-01

Extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, North American white oak (Quercus alba) and European red oak (Quercus robur). They mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid.

VLT/MUSE illuminates possible channels for Lyman continuum escape in the halo of SBS 0335-52E

NASA Astrophysics Data System (ADS)

Herenz, E. C.; Hayes, M.; Papaderos, P.; Cannon, J. M.; Bik, A.; Melinder, J.; Östlin, G.

2017-10-01

We report on the discovery of ionised gas filaments in the circum-galactic halo of the extremely metal-poor compact starburst SBS 0335-052E in a 1.5 h integration with the MUSE integral-field spectrograph. We detect these features in Hα and [O III] emission down to a limiting surface-brightness of 5 × 10-19 erg s-1 cm-2 arcsec-2. The filaments have projected diameters of 2.1 kpc and extend more than 9 kpc to the north and north-west from the main stellar body. We also detect extended nebular He II λ4686 emission that brightens towards the north-west at the rim of a starburst driven super-shell. We also present a velocity field of the ionised gas. The filaments appear to connect seamlessly in velocity space to the kinematical disturbances caused by the shell. Similar to high-z star-forming galaxies, the ionised gas in this galaxy is dispersion dominated. We argue that the filaments were created via feedback from the starburst and that these ionised structures in the halo may act as escape channels for Lyman continuum radiation in this gas-rich system. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 096.B-0690.

Erich Regener and the ionisation maximum of the atmosphere

NASA Astrophysics Data System (ADS)

Carlson, P.; Watson, A. A.

2014-12-01

In the 1930s the German physicist Erich Regener (1881-1955) did important work on the measurement of the rate of production of ionisation deep under water and in the atmosphere. Along with one of his students, Georg Pfotzer, he discovered the altitude at which the production of ionisation in the atmosphere reaches a maximum, often, but misleadingly, called the Pfotzer maximum. Regener was one of the first to estimate the energy density of cosmic rays, an estimate that was used by Baade and Zwicky to bolster their postulate that supernovae might be their source. Yet Regener's name is less recognised by present-day cosmic ray physicists than it should be, largely because in 1937 he was forced to take early retirement by the National Socialists as his wife had Jewish ancestors. In this paper we briefly review his work on cosmic rays and recommend an alternative naming of the ionisation maximum. The influence that Regener had on the field through his son, his son-in-law, his grandsons and his students, and through his links with Rutherford's group in Cambridge, is discussed in an appendix. Regener was nominated for the Nobel Prize in Physics by Schrödinger in 1938. He died in 1955 at the age of 73.

Use of active personal dosimeters in hospitals: EURADOS survey.

PubMed

Ciraj-Bjelac, Olivera; Carinou, Eleftheria; Vanhavere, Filip

2018-06-01

Considering that occupational exposure in medicine is a matter of growing concern, active personal dosimeters (APDs) are also increasingly being used in different fields of application of ionising radiation in medicine. An extensive survey to collect relevant information regarding the use of APDs in medical imaging applications of ionising radiation was organised by the EURADOS (European Radiation Dosimetry Group) Working Group 12. The objective was to collect data about the use of APDs and to identify the basic problems in the use of APDs in hospitals. APDs are most frequently used in interventional radiology and cardiology departments (54%), in nuclear medicine (29%), and in radiotherapy (12%). Most types of APDs use silicon diodes as the detector; however, in many cases their calibration is not given proper attention, as radiation beam qualities in which they are calibrated differ significantly from those in which they are actually used. The survey revealed problems related to the use of APDs, including their reliability in pulsed x-ray fields that are widely used in hospitals. Guidance from regulatory authorities and professional organisations on the testing and calibration of APDs used in hospital would likely improve the situation.

Mass spectrometry in plant metabolomics strategies: from analytical platforms to data acquisition and processing.

PubMed

Ernst, Madeleine; Silva, Denise Brentan; Silva, Ricardo Roberto; Vêncio, Ricardo Z N; Lopes, Norberto Peporine

2014-06-01

Covering: up to 2013. Plant metabolomics is a relatively recent research field that has gained increasing interest in the past few years. Up to the present day numerous review articles and guide books on the subject have been published. This review article focuses on the current applications and limitations of the modern mass spectrometry techniques, especially in combination with electrospray ionisation (ESI), an ionisation method which is most commonly applied in metabolomics studies. As a possible alternative to ESI, perspectives on matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) in metabolomics studies are introduced, a method which still is not widespread in the field. In metabolomics studies the results must always be interpreted in the context of the applied sampling procedures as well as data analysis. Different sampling strategies are introduced and the importance of data analysis is illustrated in the example of metabolic network modelling.

Impact ionisation in Al0.9Ga0.1As0.08Sb0.92 for Sb-based avalanche photodiodes

NASA Astrophysics Data System (ADS)

Collins, X.; Craig, A. P.; Roblin, T.; Marshall, A. R. J.

2018-01-01

We report the impact ionisation coefficients of the quaternary alloy Al0.9Ga0.1As0.08Sb0.92 lattice matched to GaSb substrates within the field range of 150 to 550 kV cm-1 using p-i-n and n-i-p diodes of various intrinsic thicknesses. The coefficients were found with an evolutionary fitting algorithm using a non-local recurrence based multiplication model and a variable electric field profile. These coefficients indicate that an avalanche photodiode not only can be designed to be a function in the mid-wave infrared but also can be operated at lower voltages. This is due to the high magnitude of the impact ionisation coefficients at relatively low fields compared to other III-V materials typically used in avalanche multiplication regions.

Energetic particle influences in Earth's atmosphere

NASA Astrophysics Data System (ADS)

Aplin, Karen; Harrison, R. Giles; Nicoll, Keri; Rycroft, Michael; Briggs, Aaron

2016-04-01

Energetic particles from outer space, known as galactic cosmic rays, constantly ionise the entire atmosphere. During strong solar storms, solar energetic particles can also reach the troposphere and enhance ionisation. Atmospheric ionisation generates cluster ions. These facilitate current flow in the global electric circuit, which arises from charge separation in thunderstorms driven by meteorological processes. Energetic particles, whether solar or galactic in origin, may influence the troposphere and stratosphere through a range of different mechanisms, each probably contributing a small amount. Some of the suggested processes potentially acting over a wide spatial area in the troposphere include enhanced scavenging of charged aerosol particles, modification of droplet or droplet-droplet behavior by charging, and the direct absorption of infra-red radiation by the bending and stretching of hydrogen bonds inside atmospheric cluster-ions. As well as reviewing the proposed mechanisms by which energetic particles modulate atmospheric properties, we will also discuss new instrumentation for measurement of energetic particles in the atmosphere.

Ionised Jets Associated With Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Purser, Simon John Derek

2017-09-01

This thesis focuses on the phenomena of ionised jets associated with massive young stellar objects. Firstly a study was conducted with the aim to establish a statistical sample of such objects. Radio observations towards a sample of 49 MYSOs resulted in the detection of 28 objects classified as ionised jets. The jets’ radio luminosities scaled with their MYSOs’ bolometric luminosities in the same way as for low-mass examples. This infers that the jet launching and collimation mechanisms of high-mass jets are very similar to that in their low-mass counterparts and they are ejected for the last ≤65000 yr of the MYSO phase. Interestingly non-thermal emission was regularly detected towards spatially distinct radio lobes (associated with ˜50% of the jets), suggesting the presence of synchrotron emission and therefore, magnetic fields. With an average spectral index of ¯α=‑0. 55 (indicative of the 1st order Fermi acceleration mechanism) it is concluded these lobes are the result of shocks in the jets’ stream. My second science chapter is a study of radio variability, precession and proper motions towards a subset of objects from the first chapter. Over a two year time period, no significant variability and only one example of proper motion (1800±600 km s‑1) was detected. Precession was found to be commonplace however and if it arises as the result of binary interactions, we infer orbital radii between 30 and 1800 au for the binary companions. Lastly, high-resolution, VLA observations at C and Q-bands were analysed to extend the known sample of MYSOs harbouring ionised jets into the northern hemisphere. Only 3 radio sources were detected possessing jet-like characteristics towards the work’s sub-sample of 8 IRDCs containing 44 mm-cores (in our field of view), highlighting the radio-quiet (≳30μJy) nature of this early phase in massive star formation. Towards the RMS survey derived sample of 48 MYSOs, a total of 38 radio sources with jet-like characteristics were detected, of which 14 were bona-fide jets (10 of which were associated with shock-ionised lobes). Comparing the analysis of the MYSO sample to statistical surveys of molecular outflows, it was inferred from their total momenta that the jets alone are mechanically capable of entraining the outflows. Measurement of the physical extent of the radio emission showed no evolution of the opening angle with bolometric luminosity, and that a trapped Hii region alone was not enough to explain the radio emission. Most interestingly, jets associated with shock ionised lobes were found to occupy later evolutionary IR colours than those without, suggesting them to be an evolutionary stage in ionised jet, and MYSO, evolution.

The properties of the extended warm ionised gas around low-redshift QSOs and the lack of extended high-velocity outflows

NASA Astrophysics Data System (ADS)

Husemann, B.; Wisotzki, L.; Sánchez, S. F.; Jahnke, K.

2013-01-01

We present a detailed analysis of a large sample of 31 low-redshift, mostly radio-quiet type 1 quasi-stellar objects (QSOs) observed with integral field spectroscopy to study their extended emission-line regions (EELRs). We focus on the ionisation state of the gas, size and luminosity of extended narrow line regions (ENLRs), which corresponds to those parts of the EELR dominated by ionisation from the QSO, as well as the kinematics of the ionised gas. We detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO emission and the extended host galaxy light in the integral field data with a new dedicated algorithm. Based on standard emission-line diagnostics we identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are composed of H ii regions and 3 EELRs display signatures of both ionisation mechanisms at different locations. The typical size of the ENLR is ~10 kpc at a median nuclear [O iii] luminosity of log (L([O iii])/ [ergs-1]) = 42.7 ± 0.15. We show that the ENLR sizes are least a factor of ~2 larger than determined with the Hubble Space Telescope, but are consistent with those of recently reported type 2 QSOs at matching [O iii] luminosities. The ENLR of type 1 and type 2 QSOs therefore appear to follow the same size-luminosity relation. Furthermore, we show for the first time that the ENLR size is much better correlated with the QSO continuum luminosity than with the total/nuclear [O iii] luminosity. We show that ENLR luminosity and radio luminosity are correlated, and argue that radio jets even in radio-quiet QSOs are important for shaping the properties of the ENLR. Strikingly, the kinematics of the ionised gas is quiescent and likely gravitationally driven in the majority of cases and we find only 3 objects with radial gas velocities exceeding >400 km s-1 in specific regions of the EELR that can be associate with radio jets. In general, these are significantly lower outflow velocities and detection rates compared to starburst galaxies or radio-loud QSOs. This represent a challenge for some theoretical feedback models in which luminous QSOs are expected to radiatively drive an outflow out to scales of the entire host galaxy. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max- Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Tables 3, 4, and 7 are available in electronic form at http://www.aanda.org

Single event upsets in semiconductor devices induced by highly ionising particles.

PubMed

Sannikov, A V

2004-01-01

A new model of single event upsets (SEUs), created in memory cells by heavy ions and high energy hadrons, has been developed. The model takes into account the spatial distribution of charge collection efficiency over the cell area not considered in previous approaches. Three-dimensional calculations made by the HADRON code have shown good agreement with experimental data for the energy dependence of proton SEU cross sections, sensitive depths and other SEU observables. The model is promising for prediction of SEU rates for memory chips exposed in space and in high-energy experiments as well as for the development of a high-energy neutron dosemeter based on the SEU effect.

Diagnostics of red-shifted H-alpha line emission from a C-class flare with full non-LTE radiative and hydrodynamic approach

NASA Astrophysics Data System (ADS)

Druett, M. K.; Zharkova, V. V.; Scullion, E.; Zharkov, S.; Matthews, S. A.

2016-12-01

We analyse H-alpha line profiles with strong redshifts during the C1.8 flare on 1st July 2012 obtained from the Swedish Solar Telescope (SST) closely resembling the previous observations (Wuelser and Marti, 1989). The flare has a magnetic field configuration with two levels of loop structures. The kernels with red shifts are observed in one of the H-alpha ribbons in the south-west location formed after the main impulse recorded in the north-east. The locations of H-alpha kernels with red shifts reveal close temporal and spatial correlation with weaker HXR signatures and coincide with the locations of coronal jets observed with AIA/SDO. For interpretation we apply a revised 1D hydrodynamic and non-LTE (NLTE) radiative model for 5 level plus continuum model hydrogen atom (Druett & Zharkova, 2016) considering radiative, thermal and non-thermal excitation and ionisation by beam electrons with the updated beam densities (Zharkova & Dobranskis, 2016) and analytical excitation/ionisation rates (Zharkova& Kobylinskijj, 1993). We find the simultaneous solutions of steady state and radiative transfer equations in all optically-thick lines and continua. The electron and ion temperatures, ambient density and macrovelocity of the ambient plasma are derived from a 1D hydrodynamic model with initial condition of the pre-flaring photosphere for the two fluid ambient plasma heated by beam electrons (Zharkova & Zharkov, 2007). We simulate distributions over precipitation depth of ionisation and departure coefficients for all the hydrogen atom transitions including the deviation of ionisation from Saha equation affected by non-thermal electron beams. We show that in the very first seconds after the beam onset Balmer line profiles are sensitive to the effect of beam electrons. The combination of the additional ionisation caused by beam electrons leading to a very strong Stark effect in Balmer lines with the hydrodynamic heating and formation of a low temperature shock in the chromosphere is shown to closely account for the visible asymmetric H-alpha line profiles with strong red shifts observed now and in the past. The interplay between the ambient plasma heating and non-thermal collisional excitation and ionisation rates by beam electrons is shown to define the Balmer line red shifts and continuum enhancements.

History and destiny of an emerging early-type galaxy. New IFU insights on the major-merger remnant NGC 7252

NASA Astrophysics Data System (ADS)

Weaver, J.; Husemann, B.; Kuntschner, H.; Martín-Navarro, I.; Bournaud, F.; Duc, P.-A.; Emsellem, E.; Krajnović, D.; Lyubenova, M.; McDermid, R. M.

2018-06-01

Context. The merging of galaxies is one key aspect in our favourite hierarchical ΛCDM Universe and is an important channel leading to massive quiescent elliptical galaxies. Understanding this complex transformational process is ongoing. Aims: We aim to study NGC 7252, which is one of the nearest major-merger galaxy remnants, observed 1 Gyr after the collision of presumably two gas-rich disc galaxies. It is therefore an ideal laboratory to study the processes inherent to the transformation of disc galaxies to ellipticals. Methods: We obtained wide-field IFU spectroscopy with the VLT-VIMOS integral-field spectrograph covering the central 50'' × 50'' of NGC 7252 to map the stellar and ionised gas kinematics, and the distribution and conditions of the ionised gas, revealing the extent of ongoing star formation and recent star formation history. Results: Contrary to previous studies, we find the inner gas disc not to be counter-rotating with respect to the stars. In addition, the stellar kinematics appear complex with a clear indication of a prolate-like rotation component which suggests a polar merger configuration. The ongoing star formation rate is 2.2 ± 0.6 M⊙ yr-1 and implies a typical depletion time of 2 Gyr given the molecular gas content. Furthermore, the spatially resolved star formation history suggests a slight radial dependence, moving outwards at later times. We confirm a large AGN-ionised gas cloud previously discovered 5 kpc south of the nucleus, and find a higher ionisation state of the ionised gas at the galaxy centre relative to the surrounding gas disc. Although the higher ionisation towards the centre is potentially degenerate within the central star forming ring, it may be associated with a low-luminosity AGN. Conclusions: Although NGC 7252 has been classified as post-starburst galaxy at the centre, the elliptical-like major-merger remnant still appears very active. A central kpc-scale gas disc has presumably re-formed quickly within the last 100 Myr after final coalescence. The disc features ongoing star formation, implying Gyr long timescale to reach the red sequence through gas consumption alone. While NGC 7252 is useful to probe the transformation from discs to ellipticals, it is not well-suited to study the transformation from blue to red at this point.

Characterization of the polyphenolic composition of purple loosestrife (Lythrum salicaria).

PubMed

Rauha, J P; Wolfender, J L; Salminen, J P; Pihlaja, K; Hostettmann, K; Vuorela, H

2001-01-01

Phenolic compounds of purple loosestrife (Lythrum salicaria L.) were analysed by the use of liquid chromatography-mass spectrometry (LC/MS) equipped with atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI). The presence of vitexin and orientin as well as their isomers, isovitexin and isoorientin, were confirmed using ion trap multiple stage LC/MS3 analysis. Several phenolic acids and tannins were also detected. Ellagitannins, vescalagin and pedunculagin, are reported from the plant for the first time.

Equation-of-motion coupled-cluster method for ionised states with spin-orbit coupling using open-shell reference wavefunction

NASA Astrophysics Data System (ADS)

Wang, Zhifan; Wang, Fan

2018-04-01

The equation-of-motion coupled-cluster method for ionised states at the singles and doubles level (EOM-IP-CCSD) with spin-orbit coupling (SOC) included in post-Hartree-Fock (HF) steps is extended to spatially non-degenerate open-shell systems such as high spin states of s1, p3, σ1 or π2 configuration in this work. Pseudopotentials are employed to treat relativistic effects and spin-unrestricted scalar relativistic HF determinant is adopted as reference in calculations. Symmetry is not exploited in the implementation since both time-reversal and spatial symmetry is broken due to SOC. IPs with the EOM-IP-CCSD approach are those from the 3Σ1- states for high spin state of π2 configuration, while the ground state is the 3Σ0- state. When removing an electron from the high spin state of p3 configuration, only the 3P2 state can be reached. The open-shell EOM-IP-CCSD approach with SOC was employed in calculating IPs of some open-shell atoms with s1 configuration, diatomic molecules with π2 configuration and SOC splitting of the ionised π1 state, as well as IPs of VA atoms with p3 configuration. Our results demonstrate that this approach can be applied to ionised states of spatially non-degenerate open-shell states containing heavy elements with reasonable accuracy.

Radiation safety knowledge and practices among Irish orthopaedic trainees.

PubMed

Nugent, M; Carmody, O; Dudeney, S

2015-06-01

Fluoroscopy is frequently used in orthopaedic surgery, particularly in a trauma setting. Exposure of patients and staff to ionising radiation has been studied extensively; however, little work has been done to evaluate current knowledge and practices among orthopaedic trainees. This study aimed to investigate the knowledge and practices of Irish orthopaedic trainees regarding use of ionising radiation. A confidential internet-based survey on workplace radiation safety practices was distributed via email to 40 higher specialist trainees. Questions included related to radiation safety training and regular work practices. A total of 26 trainees completed the questionnaire (65% response rate). All reported regular exposure to ionising radiation. Compliance with body shields was high (25, 96%), however, other protective measures such as thyroid shields were less frequently employed. The 'as low as reasonably achievable principle' was practised regularly by 14 (54%). Radiation safety training was variable-while just over half (14) respondents felt adequately trained in radiation safety, 17 (65%) had attended a radiation protection course. Use of dosimeters was particularly poor, with only 4 (15%) using them regularly and most citing lack of availability as the main barrier. Although most Irish orthopaedic trainees have some knowledge regarding radiation safety, many do not regularly use all available measures to reduce exposure to ionising radiation. Barriers to use of protective mechanisms include lack of availability and perceived impracticality.

Retention of ionisable compounds on high-performance liquid chromatography XVII. Estimation of the pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase.

PubMed

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2007-01-05

The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase.

Evidence for a Circum-Nuclear and Ionised Absorber in the X-ray Obscured Broad Line Radio Galaxy 3C 445

NASA Technical Reports Server (NTRS)

Braito, V.; Reeves, J. N.; Sambruna, R. M.; Gofford, J.

2012-01-01

Here we present the results of a Suzaku observation of the Broad Line Radio Galaxy 3C 445. We confirm the results obtained with the previous X-ray observations which unveiled the presence of several soft X-ray emission lines and an overall X-ray emission which strongly resembles a typical Seyfert 2 despite of the optical classification as an unobscured AGN. The broad band spectrum allowed us to measure for the first time the amount of reflection (R approximately 0.9) which together with the relatively strong neutral Fe Ka emission line (EW approximately 100 eV) strongly supports a scenario where a Compton-thick mirror is present. The primary X ray continuum is strongly obscured by an absorber with a column density of NH = 2 - 3 x 10(exp 23) per square centimeter. Two possible scenarios are proposed for the absorber: a neutral partial covering or a mildly ionised absorber with an ionisation parameter log xi approximately 1.0 erg centimeter per second. A comparison with the past and more recent X-ray observations of 3C 445 performed with XMM-Newton and Chandra is presented, which provided tentative evidence that the ionised and outflowing absorber varied. We argue that the absorber is probably associated with an equatorial diskwind located within the parsec scale molecular torus.

The effects of UV light on calcium metabolism in ball pythons (Python regius).

PubMed

Hedley, J; Eatwell, K

2013-10-12

Despite the popularity of keeping snakes in captivity, there has been limited investigation into the effects of UV radiation on vitamin D levels in snakes. The aim of this study was to investigate the effects of UV-b radiation on plasma 25-hydroxyvitamin D3 levels and ionised calcium concentrations in ball pythons (Python regius). Blood samples were taken from 14 ball pythons, which had never been exposed to UV-b light, to obtain baseline 25-hydroxyvitamin D3 levels and ionised calcium concentrations. Blood samples were then taken again from the same snakes 70 days later after one group (Group 1, n=6 females) were exposed to UV-b radiation daily, and the other group (Group 2, n=5 males and 3 females) were exposed to no UV-b radiation. Mean±sd 25-hydroxyvitamin D3 levels on day 0 in Group 1 were 197±35 nmol/l, and on day 70 were 203.5±13.8 nmol/l. Mean±sd 25-hydroxyvitamin D3 levels in Group 2 on day 0 were 77.7±41.5 nmol/l, and on day 70 were 83.0±41.9 nmol/l. Mean±sd ionised calcium levels at day 0 were 1.84±0.05 mmol/l for Group 1, and on day 70 were 1.78±0.07 mmol/l. Mean±sd ionised calcium levels at day 0 were 1.79±0.07 mmol/l for Group 2, and on day 70 were 1.81±0.05 mmol/l. No association was demonstrated between exposure to UV-b radiation and plasma 25-hydroxyvitamin D3 and ionised calcium concentrations. These results may provide baseline parameters for future studies in this and other snake species to determine ability to utilise UV-b light for vitamin D production.

Prevalence of working smoke alarms in local authority inner city housing: randomised controlled trial

PubMed Central

Rowland, Diane; DiGuiseppi, Carolyn; Roberts, Ian; Curtis, Katherine; Roberts, Helen; Ginnelly, Laura; Sculpher, Mark; Wade, Angela

2002-01-01

Objectives To identify which type of smoke alarm is most likely to remain working in local authority inner city housing, and to identify an alarm tolerated in households with smokers. Design Randomised controlled trial. Setting Two local authority housing estates in inner London. Participants 2145 households. Intervention Installation of one of five types of smoke alarm (ionisation sensor with a zinc battery; ionisation sensor with a zinc battery and pause button; ionisation sensor with a lithium battery and pause button; optical sensor with a lithium battery; or optical sensor with a zinc battery). Main outcome measure Percentage of homes with any working alarm and percentage in which the alarm installed for this study was working after 15 months. Results 54.4% (1166/2145) of all households and 45.9% (465/1012) of households occupied by smokers had a working smoke alarm. Ionisation sensor, lithium battery, and there being a smoker in the household were independently associated with whether an alarm was working (adjusted odds ratios 2.24 (95% confidence interval 1.75 to 2.87), 2.20 (1.77 to 2.75), and 0.62 (0.52 to 0.74)). The most common reasons for non-function were missing battery (19%), missing alarm (17%), and battery disconnected (4%). Conclusions Nearly half of the alarms installed were not working when tested 15 months later. Type of alarm and power source are important determinants of whether a household had a working alarm. What is already known on this topicFunctioning smoke alarms can reduce the risk of death in the event of a house fireMany local authorities install smoke alarms in their propertiesSeveral different types of smoke alarm are availableWhat this study addsOnly half of the smoke alarms installed in local authority housing were still working 15 months laterIonising smoke alarms with long life lithium batteries were most likely to remain functioningInstalling smoke alarms may not be an effective use of resources PMID:12411356

Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

NASA Astrophysics Data System (ADS)

Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

2016-07-01

Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

Subclinical hypocalcaemia in captive Asian elephants (Elephas maximus).

PubMed

van der Kolk, J H; van Leeuwen, J P T M; van den Belt, A J M; van Schaik, R H N; Schaftenaar, W

2008-04-12

The hypothesis that hypocalcaemia may play a role in dystocia in captive Asian elephants (Elephas maximus) was investigated. The objectives of the study were to measure the total calcium concentration in elephant plasma; assess the changes in parameters of calcium metabolism during a feeding trial; investigate a possible relationship between calcium metabolism and dystocia; and assess bone mineralisation in captive Asian elephants in vivo. The following parameters were measured: total and ionised calcium, inorganic phosphorous and magnesium, the fractional excretions of these minerals, intact parathyroid hormone, 25-OH-D(3) and 1,25-OH-D(3). Radiographs were taken from tail vertebrae for assessment of bone mineralisation. The mean (sd) heparinised plasma total calcium concentration was 2.7 (0.33) mmol/l (n=43) ranging from 0.84 to 3.08 mmol/l in 11 Asian elephants. There was no significant correlation between plasma total calcium concentration and age. Following feeding of a calcium rich ration to four captive Asian elephant cows, plasma total and ionised calcium peaked at 3.6 (0.24) mmol/l (range 3.4 to 3.9 mmol/l) and 1.25 (0.07) mmol/l (range 1.17 to 1.32 mmol/l), respectively. Plasma ionised calcium concentrations around parturition in four Asian elephant cows ranged from 0.37 to 1.1 mmol/l only. The present study indicates that captive Asian elephants might be hypocalcaemic, and that, in captive Asian elephants, the normal plasma concentration of total calcium should actually be around 3.6 mmol/l and normal plasma concentration of ionised calcium around 1.25 mmol/l. Given the fact that elephants absorb dietary calcium mainly from the intestine, it could be concluded that elephants should be fed calcium-rich diets at all times, and particularly around parturition. In addition, normal values for ionised calcium in captive Asian elephants should be reassessed.

Beta-decay measurements of neutron-rich thallium, lead, and bismuth by means of resonant laser ionisation

NASA Astrophysics Data System (ADS)

Franchoo, S.; de Witte, H.; Andreyev, A. N.; Cederka¨Ll, J.; Dean, S.; de Smet, A.; Eeckhaudt, S.; Fedorov, D. V.; Fedosseev, V. N.; G´Rska, M.; Huber, G.; Huyse, M.; Janas, Z.; Ko¨Ster, U.; Kurcewicz, W.; Kurpeta, J.; Mayer, P.; Płchocki, A.; van de Vel, K.; van Duppen, P.; Weissman, L.; Isolde Collaboration

2004-04-01

Neutron-rich thallium, lead, and bismuth isotopes were investigated at the ISOLDE facility. After mass separation and resonant laser ionisation of the produced activity, new spectroscopic data were obtained for 215,218Bi and 215Pb. An attempt to reach heavy thallium had to be abandoned because of a strong francium component in the beam that gave rise to a neutron background through (α,n) reactions on the aluminium walls of the experimental chamber.

A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition

NASA Astrophysics Data System (ADS)

Gill, Martin R.; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A.; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A.

2016-08-01

Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)]2+ before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition.

PubMed

Gill, Martin R; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A

2016-08-25

Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)](2+) (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)](2+) before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

NASA Astrophysics Data System (ADS)

Bannan, T.; Booth, M.; Benyezzar, M.; Bacak, A.; Alfarra, M. R. R.; Topping, D. O.; Percival, C.

2015-12-01

Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

NASA Astrophysics Data System (ADS)

Bannan, Thomas; Booth, A. Murray; Alfarra, Rami; Bacak, Asan; Pericval, Carl

2016-04-01

Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

A comprehensive metabolite profiling of Isatis tinctoria leaf extracts.

PubMed

Mohn, Tobias; Plitzko, Inken; Hamburger, Matthias

2009-05-01

A broad-based characterisation of a pharmacologically active dichloromethane extract from Isatis tinctoria leaves was carried out. For a comprehensive picture we also included the polar constituents of I. tinctoria (MeOH extract) and for comparative purposes, the taxonomically closely related plant I. indigotica. Diode array detector, evaporative light scattering detector, atmospheric pressure chemical ionisation and electrospray ionisation mass spectrometry, and electrospray ionisation time-of-flight mass spectrometry detectors were used in parallel to ensure a wide coverage of secondary metabolites with highly diverging analytical properties. Off-line microprobe nuclear magnetic resonance spectroscopy after peak purification by semi-preparative high-pressure liquid chromatography served for structure elucidation of some minor constituents. More than 65 compounds belonging to various structural classes such as alkaloids, flavonoids, fatty acids, porphyrins, lignans, carotenoids, glucosinolates and cyclohexenones were unambiguously identified, and tentative structures were proposed for additional compounds. Numerous compounds were identified for the first time in the genus Isatis, and an indolic alkaloid was discovered.

Nonlinear collisionless electron cyclotron interaction in the pre-ionisation stage

NASA Astrophysics Data System (ADS)

Farina, D.

2018-06-01

Electron cyclotron (EC) wave-particle interaction is theoretically investigated in the pre-ionisation phase, much before collisions and other mechanisms can play a role. In the very first phase of a plasma discharge with EC-assisted breakdown, the motion of an electron at room temperature in a static magnetic field under the action of a localised microwave beam is nonlinear, and transition to states of larger energy can occur via wave trapping. Within a Hamiltonian adiabatic formalism, the conditions at which the particles gain energy in single beam crossing are derived in a rigorous way, and the energy variation is characterized quantitatively as a function of the wave frequency, harmonic number, polarisation and EC power and beam width. Estimates of interest for applications to tokamak start-up are obtained for the first, second and third cyclotron harmonic. The investigation confirms that electrons can easily gain energies well above the ionisation energy in most conditions at the first two harmonics, while not at the third harmonic, as observed in experiments.

Using corona discharge-ion mobility spectrometry for detection of 2,4,6-Trichloroanisole.

PubMed

Lichvanová, Zuzana; Ilbeigi, Vahideh; Sabo, Martin; Tabrizchi, Mahmoud; Matejčík, Stefan

2014-09-01

In this work possible application of the corona discharge-ion mobility spectrometer (CD-IMS) for detection of 2,4,6-Trichloroanisole (TCA) has been investigated. We applied CD-IMS interfaced with orthogonal acceleration time of flight mass spectrometer (CD-IMS-oaTOF) to study the ion processes within the CD-IMS technique. The CD-IMS instrument was operated in two modes, (i) standard and (ii) reverse flow modes resulting in different chemical ionisation schemes by NO3(-)(HNO3)n (n=0,1,2) and O2(-)(H2O)n (n=0,1,2), respectively. The O2(-)(H2O)n ionisation was associated with formation of Cl(-) and (TCA-CH3)(-) ions from TCA. The NO3(-)(HNO3)n ionisation, resulted in formation of NO3(-)(HNO3)(TCA-Cl) adduct ions. Limit of detection (LOD) for TCA was determined in gas (100 ppb) and solid phases (150 ng). Copyright © 2014 Elsevier B.V. All rights reserved.

Nanodosimetric track structure in homogeneous extended beams.

PubMed

Conte, V; Moro, D; Colautti, P; Grosswendt, B

2015-09-01

Physical aspects of particle track structure are important in determining the induction of clustered damage in relevant subcellular structures like the DNA and higher-order genomic structures. The direct measurement of track-structure properties of ionising radiation is feasible today by counting the number of ionisations produced inside a small gas volume. In particular, the so-called track-nanodosimeter, installed at the TANDEM-ALPI accelerator complex of LNL, measures ionisation cluster-size distributions in a simulated subcellular structure of dimensions 20 nm, corresponding approximately to the diameter of the chromatin fibre. The target volume is irradiated by pencil beams of primary particles passing at specified impact parameter. To directly relate these measured track-structure data to radiobiological measurements performed in broad homogeneous particle beams, these data can be integrated over the impact parameter. This procedure was successfully applied to 240 MeV carbon ions and compared with Monte Carlo simulations for extended fields. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Identification of amino acids by material enhanced laser desorption/ionisation mass spectrometry (MELDI-MS) in positive- and negative-ion mode

NASA Astrophysics Data System (ADS)

Hashir, Muhammad Ahsan; Stecher, Guenther; Mayr, Stefan; Bonn, Guenther K.

2009-01-01

In the present study, different silica gel modifications were evaluated for their application as target surface for material enhanced laser desorption/ionisation mass spectrometric (MELDI-MS) investigation of amino acids. 4,4'-Azodianiline (ADA-silica) modified silica gel was successfully employed for the qualitative analysis of amino acids in positive- and in negative-ion mode. Further no derivatisation of amino acids was necessary, as the introduced system allowed the direct analysis of targets and delivered spectra with excellent signal intensity and signal-to-noise ratio within a few minutes. The influence of surface chemistry, ionisation mode and the nature of analytes on signal intensity was studied and discussed. Detection limit of 2.10 pg (10 fmol) was achieved by employing ADA-silica in positive-ion mode. Finally, xylem saps from different types of trees were analysed. This proved the high performance and excellent behaviour of the introduced target surface material.

Effects of autoionising states on the single and double ionisation yields of neon with soft X-ray fields. JMO Series: Attosecond and Strong Field Science

NASA Astrophysics Data System (ADS)

Middleton, D. P. W.; Nikolopoulos, L. A. A.

2012-11-01

In this work, single and double ionisation yields of neon under extreme ultraviolet free-electron laser (FEL) radiation tuned in the vicinity of the autoionising states (AIS) of Ne+ were studied. Density matrix equations were developed and were used to calculate the dependence of the branching ratios of singly and doubly ionised neon on the field intensity and its duration. In addition, in response to a recent experiment [M. Martins et al., Phys. Rev. A 2011, 80, 023411], a quantitative analysis was undertaken in order to reproduce the magnitude of the branching ratios by varying the FEL photon frequency in the range 41.0-42.0 eV in accordance with the experimental report. While the reported variations of the species' branching ratios as a function of the FEL field's photon energy were found, their magnitude and shape differ. In general, the branching ratios are found to be heavily dependent on the given combination of the peak intensity and the pulse duration. Furthermore, the FEL's stochastic fluctuation has been modelled by solving the average density matrix equations and it was found that stochastic effects should also affect branching ratios, mainly due to the increase in the effective bandwidth of the pulse in comparison with the AIS's decay ionisation width. Our calculations suggest that field fluctuations generally diminish the resonance features of the branching ratios.

Simulation and measurements of the response of an air ionisation chamber exposed to a mixed high-energy radiation field.

PubMed

Vincke, Helmut; Forkel-Wirth, Doris; Perrin, Daniel; Theis, Chris

2005-01-01

CERN's radiation protection group operates a network of simple and robust ionisation chambers that are installed inside CERN's accelerator tunnels. These ionisation chambers are used for the remote reading of ambient dose rate equivalents inside the machines during beam-off periods. This Radiation Protection Monitor for dose rates due to Induced Radioactivity ('PMI', trade name: PTW, Type 34031) is a non-confined air ionisation plastic chamber which is operated under atmospheric pressure. Besides its current field of operation it is planned to extend the use of this detector in the Large Hadron Collider to measure radiation under beam operation conditions to obtain an indication of the machine performance. Until now, studies of the PMI detector have been limited to the response to photons. In order to evaluate its response to other radiation components, this chamber type was tested at CERF, the high-energy reference field facility at CERN. Six PMI detectors were installed around a copper target being irradiated by a mixed hadron beam with a momentum of 120 GeV c(-1). Each of the chosen detector positions was defined by a different radiation field, varying in type and energy of the incident particles. For all positions, detailed measurements and FLUKA simulations of the detector response were performed. This paper presents the promising comparison between the measurements and simulations and analyses the influence of the different particle types on the resulting detector response.

A Census of the LyC Photons that Form the UV Background During Reionization

NASA Astrophysics Data System (ADS)

Katz, Harley; Kimm, Taysun; Haehnelt, Martin; Sijacki, Debora; Rosdahl, Joakim; Blaizot, Jeremy

2018-05-01

We present a new, on-the-fly photon flux and absorption tracer algorithm designed to directly measure the contribution of different source populations to the metagalactic UV background and to the ionisation fraction of gas in the Universe. We use a suite of multifrequency radiation hydrodynamics simulations that are carefully calibrated to reproduce a realistic reionization history and galaxy properties at z ≥ 6, to disentangle the contribution of photons emitted by different mass haloes and by stars with different metallicities and ages to the UV background during reionization. While at very early cosmic times low mass, metal poor haloes provide most of the LyC photons, their contribution decreases steadily with time. At z = 6 it is the photons emitted by massive systems (Mhalo/M⊙ > 1010 h-1) and by the metal enriched stars (10-3 < Z/Z⊙ < 10-1.5) that provide the largest contribution to the ionising UV background. We demonstrate that there are large variations in the escape fraction depending on the source, with the escape fraction being highest (˜45 - 60%) for photons emitted by the oldest stars that penetrate into the IGM via low opacity channels carved by the ionising photons and supernova from younger stars. Before HII regions begin to overlap, the photoionisation rate strongly fluctuates between different, isolated HII bubbles, depending on the embedded ionising source, which we suggest may result in spatial variations in the properties of dwarf galaxies.

Evolution of star formation conditions from high-redshift to low-redshift

NASA Astrophysics Data System (ADS)

Shirazi, Maryam

2015-08-01

There are some hints indicating extreme interstellar medium (ISM) conditions at high redshift e.g., harder ionsing radiation fields and higher electron densities. By analysing the ionisation state of galaxies using their [OIII]5007/[OII]3727 line ratios we recently showed that star-forming galaxies at z~ 1. 5 -- 3. 5 have higher ionisation parameters and higher gas densities relative to that of local galaxies with similar global properties (Shirazi et al. 2014). This means the intrinsic properties e.g., the density of star forming regions at high redshift is different from what we observe in the local Universe. Based on the distribution of galaxies in the BPT diagram, it is proposed that the transition to nearby like conditions happen at 0. 8 < z < 1. 5 (Kewley et al 2013). However, we do not know how star-forming regions of the intermediate redshift galaxies are compared to that of high redshift galaxies that have higher gas fractions and are close to the peak of star formation activity in the Universe. We use the unique capability of the MUSE to indirectly trace the ISM conditions at those redshifts. We measure the spatially-resolved ionisation parameter using [OIII ]5007/ [O II]3727 ratio and we measure the spatially resolved gas density using the [OII] 3727,3729 doublet. We probe the spatial distributions of the ionisation parameter and gas density and search for systematic differences between high, intermediate and low redshift galaxies in terms of their global galaxy properties.

Quantitative fluorescence measurements performed on typical matrix molecules in matrix-assisted laser desorption/ionisation

NASA Astrophysics Data System (ADS)

Allwood, D. A.; Dyer, P. E.

2000-11-01

Fundamental photophysical parameters have been determined for several molecules that are commonly used as matrices, e.g. ferulic acid, within matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Fluorescence quantum efficiencies ( φqe), singlet decay rates ( kl), vibrationless ground-singlet transition energies and average fluorescence wavelengths have been obtained from solid and solution samples by quantitative optical measurements. This new data will assist in modelling calculations of MALDI processes and in highlighting desirable characteristics of MALDI matrices. φqe may be as high as 0.59 whilst the radiative decay rate ( kf) appears to be within the (0.8-4)×10 8 s -1 range. Interestingly, α-cyano-4-hydroxycinnamic acid (α-CHC) has a very low φqe and fast non-radiative decay rate which would imply a rapid and efficient thermalisation of electronic excitation. This is in keeping with observations that α-CHC exhibits low threshold fluences for ion detection and the low fluences at which α-CHC tends to fragment.

Nanotechnology-supported THz medical imaging

PubMed Central

Stylianou, Andreas; Talias, Michael A

2013-01-01

Over the last few decades, the achievements and progress in the field of medical imaging have dramatically enhanced the early detection and treatment of many pathological conditions. The development of new imaging modalities, especially non-ionising ones, which will improve prognosis, is of crucial importance. A number of novel imaging modalities have been developed but they are still in the initial stages of development and serious drawbacks obstruct them from offering their benefits to the medical field. In the 21 st century, it is believed that nanotechnology will highly influence our everyday life and dramatically change the world of medicine, including medical imaging. Here we discuss how nanotechnology, which is still in its infancy, can improve Terahertz (THz) imaging, an emerging imaging modality, and how it may find its way into real clinical applications. THz imaging is characterised by the use of non-ionising radiation and although it has the potential to be used in many biomedical fields, it remains in the field of basic research. An extensive review of the recent available literature shows how the current state of this emerging imaging modality can be transformed by nanotechnology. Innovative scientific concepts that use nanotechnology-based techniques to overcome some of the limitations of the use of THz imaging are discussed. We review a number of drawbacks, such as a low contrast mechanism, poor source performance and bulky THz systems, which characterise present THz medical imaging and suggest how they can be overcome through nanotechnology. Better resolution and higher detection sensitivity can also be achieved using nanotechnology techniques. PMID:24555052

Rapid Identification of unstable acyl glucoside flavonoids of Oxytropis racemosa Turcz by high-performance liquid chromatography-diode array detection-electrospray ionisation/multi-stage mass spectrometry.

PubMed

Song, Shuang; Zheng, Xiu-Ping; Liu, Wei-Dong; Du, Rui-Fang; Feng, Zi-Ming; Zhang, Pei-Cheng; Bi, Li-Fu

2013-02-01

Oxytropis racemosa Turcz is an important minority medicine that is used mainly to improve children's indigestion, especially in inner Mongolia and Tibet. Previous studies indicated that the characteristic constituents of this plant are acylated flavonoids. Rapidly identify the characteristic chemical constituents of O. racemosa by high-performance liquid chromatography-diode array detection-electrospray ionisation/multi-stage mass spectrometry (HPLC-DAD-ESI/MS(n) ) and suggest a useful method to control the quality of this medicinal plant. In the HPLC fingerprint, 32 flavonoids were tentatively identified by a detailed analysis of their mass spectra, UV spectra and retention times. Furthermore, 13 flavonoids were confirmed by comparison with previously isolated compounds obtained from O. racemosa. In total, 32 flavonoids, including 13 flavonoids with 3-hydroxy-3-methylglutaric acid (HMG) moieties and four flavonoids with 3-malonyl moieties, were identified in the extract of O. racemosa. Among the compounds identified, 10 were characterised as new compounds for their particular acylated sugar moieties. The method described is effective for obtaining a comprehensive phytochemical profile of plants containing unstable acylated flavonoids. The method is also useful for constructing the chromatographic fingerprint of the minority medicine -O. racemosa Turcz for quality control. Copyright © 2012 John Wiley & Sons, Ltd.

Comparison of phenotypic methods and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry for the identification of aero-tolerant Actinomyces spp. isolated from soft-tissue infections.

PubMed

Ng, L S Y; Sim, J H C; Eng, L C; Menon, S; Tan, T Y

2012-08-01

Aero-tolerant Actinomyces spp. are an under-recognised cause of cutaneous infections, in part because identification using conventional phenotypic methods is difficult and may be inaccurate. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is a promising new technique for bacterial identification, but with limited data on the identification of aero-tolerant Actinomyces spp. This study evaluated the accuracy of a phenotypic biochemical kit, MALDI-TOF MS and genotypic identification methods for the identification of this problematic group of organisms. Thirty aero-tolerant Actinomyces spp. were isolated from soft-tissue infections over a 2-year period. Species identification was performed by 16 s rRNA sequencing and genotypic results were compared with results obtained by API Coryne and MALDI-TOF MS. There was poor agreement between API Coryne and genotypic identification, with only 33% of isolates correctly identified to the species level. MALDI-TOF MS correctly identified 97% of isolates to the species level, with 33% of identifications achieved with high confidence scores. MALDI-TOF MS is a promising new tool for the identification of aero-tolerant Actinomyces spp., but improvement of the database is required in order to increase the confidence level of identification.

Effectiveness of biplane angiography compared to monoplane angiography for vascular neuro-interventions: a systematic review of the literature.

PubMed

Bellemare, C A; Poder, T G

2017-07-01

To compare biplane technology to monoplane technology for vascular neuro-intervention. A systematic review of the literature in MEDLINE (via PubMed), Scopus, and ScienceDirect was conducted without date or language restrictions. The Downs and Black quality-assessment checklist was used. The findings of this systematic review were combined with local and Canadian data. The nine articles selected for analysis had a very low level of evidence. The studies report that the biplane system appears to reduce ionising radiation and medical complications as well as shorten procedure time. Most major hospitals in Canada use the biplane system. The biplane system could improve the operator's confidence, which could translate into reduced risk, especially for more complex procedures. The superiority of the biplane system cannot be scientifically proven based on the data in the literature. Nevertheless, given the advantages that a biplane system can provide in terms of safety, quality of care, support to university teaching programmes based on best practices, enhanced capability in performing complex procedures, this technology should be implemented with a responsibility to collect outcome data to optimise the clinical protocol regarding the dose of ionising radiation delivered. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Design and performance of an ionisation chamber for the measurement of low alpha-activities

NASA Astrophysics Data System (ADS)

Hartmann, A.; Hutsch, J.; Krüger, F.; Sobiella, M.; Wilsenach, H.; Zuber, K.

2016-04-01

A new ionisation chamber for alpha-spectroscopy has been built from radio-pure materials for the purpose of investigating long lived alpha-decays. The measurement makes use of pulse shape analysis to discriminate between signal and background events. The design and performance of the chamber is described in this paper. A background rate of (10.9 ± 0.6) counts per day in the energy region of 1-9 MeV was achieved with a run period of 30.8 days. The background is dominantly produced by radon daughters.

Electron removal from H and He atoms in collisions with C q+ , O q+ ions

NASA Astrophysics Data System (ADS)

Janev, R. K.; McDowell, M. R. C.

1984-06-01

Cross sections for electron capture and ionisation in collision of partially and completely stripped C q+ , N q+ and O q+ ions with hydrogen and helium atoms have been calculated at selected energies. The classical trajectory Monte Carlo method was used with a variable-charge pseudopotential to describe the interaction of the active electron with the projectile ion. A scalling relationship has been derived for the electron removal (capture and ionisation) cross section which allows a unifield representation of the data.

Biological Effects of Ionising Radiation and Countermeasures (Les effets biologiques des rayonnements ionisants et leurs contre-mesures)

DTIC Science & Technology

2018-01-01

promote cooperative research and information exchange, and secondly an in-house delivery business model where S&T activities are conducted in a NATO...Panel These Panels and Group are the power-house of the collaborative model and are made up of national representatives as well as recognised world...of Radiation Injury and Recovery 1-31 1.3.3.2 Mini-Pig Model of Acute Radiation Syndrome ( ARS ) 1-31 1.3.3.3 Medical Countermeasures (MedCM) 1-32

Current status of matrix-assisted laser desorption ionisation-time of flight mass spectrometry in the clinical microbiology laboratory.

PubMed

Kok, Jen; Chen, Sharon C A; Dwyer, Dominic E; Iredell, Jonathan R

2013-01-01

The integration of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) into many clinical microbiology laboratories has revolutionised routine pathogen identification. MALDI-TOF MS complements and has good potential to replace existing phenotypic identification methods. Results are available in a more clinically relevant timeframe, particularly in bacteraemic septic shock. Novel applications include strain typing and the detection of antimicrobial resistance, but these are not widely used. This review discusses the technical aspects, current applications, and limitations of MALDI-TOF MS.

Thermoluminescence solid-state nanodosimetry—the peak 5A/5 dosemeter

PubMed Central

Fuks, E.; Horowitz, Y. S.; Horowitz, A.; Oster, L.; Marino, S.; Rainer, M.; Rosenfeld, A.; Datz, H.

2011-01-01

The shape of composite peak 5 in the glow curve of LiF:Mg,Ti (TLD-100) following 90Sr/90Y beta irradiation, previously demonstrated to be dependent on the cooling rate used in the 400°C pre-irradiation anneal, is shown to be dependent on ionisation density in both naturally cooled and slow-cooled samples. Following heavy-charged particle high-ionisation density (HID) irradiation, the temperature of composite peak 5 decreases by ∼5°C and the peak becomes broader. This behaviour is attributed to an increase in the relative intensity of peak 5a (a low-temperature satellite of peak 5). The relative intensity of peak 5a is estimated using a computerised glow curve deconvolution code based on first-order kinetics. The analysis uses kinetic parameters for peaks 4 and 5 determined from ancillary measurements resulting in nearly ‘single-glow peak’ curves for both the peaks. In the slow-cooled samples, owing to the increased relative intensity of peak 5a compared with the naturally cooled samples, the precision of the measurement of the 5a/5 intensity ratio is found to be ∼15 % (1 SD) compared with ∼25 % for the naturally cooled samples. The ratio of peak 5a/5 in the slow-cooled samples is found to increase systematically and gradually through a variety of radiation fields from a minimum value of 0.13±0.02 for 90Sr/90Y low-ionisation density irradiations to a maximum value of ∼0.8 for 20 MeV Cu and I ion HID irradiations. Irradiation by low-energy electrons of energy 0.1–1.5 keV results in values between 1.27 and 0.95, respectively. The increasing values of the ratio of peak 5a/5 with increasing ionisation density demonstrate the viability of the concept of the peak 5a/5 nanodosemeter and its potential in the measurement of average ionisation density in a ‘nanoscopic’ mass containing the trapping centre/luminescent centre spatially correlated molecule giving rise to composite peak 5. PMID:21149323

The evolution of young HII regions. I. Continuum emission and internal dynamics

NASA Astrophysics Data System (ADS)

Klaassen, P. D.; Johnston, K. G.; Urquhart, J. S.; Mottram, J. C.; Peters, T.; Kuiper, R.; Beuther, H.; van der Tak, F. F. S.; Goddi, C.

2018-04-01

Context. High-mass stars form in much richer environments than those associated with isolated low-mass stars, and once they reach a certain mass, produce ionised (HII) regions. The formation of these pockets of ionised gas are unique to the formation of high-mass stars (M > 8 M⊙), and present an excellent opportunity to study the final stages of accretion, which could include accretion through the HII region itself. Aim. This study of the dynamics of the gas on both sides of these ionisation boundaries in very young HII regions aims to quantify the relationship between the HII regions and their immediate environments. Methods: We present high-resolution ( 0.5″) ALMA observations of nine HII regions selected from the red MSX source survey with compact radio emission and bolometric luminosities greater than 104 L⊙. We focus on the initial presentation of the data, including initial results from the radio recombination line H29α, some complementary molecules, and the 256 GHz continuum emission. Results: Of the six (out of nine) regions with H29α detections, two appear to have cometary morphologies with velocity gradients across them, and two appear more spherical with velocity gradients suggestive of infalling ionised gas. The remaining two were either observed at low resolution or had signals that were too weak to draw robust conclusions. We also present a description of the interactions between the ionised and molecular gas (as traced by CS (J = 5 - 4)), often (but not always) finding the HII region had cleared its immediate vicinity of molecules. Conclusions: Of our sample of nine, the observations of the two clusters expected to have the youngest HII regions (from previous radio observations) are suggestive of having infalling motions in the H29α emission, which could be indicative of late stage accretion onto the stars despite the presence of an HII region. Table A.2 is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A99

The nature of luminous Lyα emitters at z ˜ 2-3: maximal dust-poor starbursts and highly ionising AGN

NASA Astrophysics Data System (ADS)

Sobral, David; Matthee, Jorryt; Darvish, Behnam; Smail, Ian; Best, Philip N.; Alegre, Lara; Röttgering, Huub; Mobasher, Bahram; Stroe, Ana Paulino-Afonso Andra; Oteo, Iván

2018-03-01

Deep narrow-band surveys have revealed a large population of faint Lyα emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources (L_Lyα {≳} 10^{42.7} erg s-1; L_Lyα {≳} L^*_{Lyα }). Here we present the spectroscopic follow-up of 21 luminous LAEs at z ˜ 2 - 3 found with panoramic narrow-band surveys over five independent extragalactic fields (≈4 × 106 Mpc3 surveyed at z ˜ 2.2 and z ˜ 3.1). We use WHT/ISIS, Keck/DEIMOS and VLT/X-SHOOTER to study these sources using high ionisation UV lines. Luminous LAEs at z ˜ 2-3 have blue UV slopes (β =-2.0^{+0.3}_{-0.1}), high Lyα escape fractions (50^{+20}_{-15}%) and span five orders of magnitude in UV luminosity (M_{UV}≈ -19 to -24). Many (70%) show at least one high ionisation rest-frame UV line such as CIV, NV, CIII], HEII or OIII], typically blue-shifted by ≈100 - 200 km s-1 relative to Lyα. Their Lyα profiles reveal a wide variety of shapes, including significant blue-shifted components and widths from 200 to 4000 km s-1. Overall, 60 ± 11 % appear to be AGN dominated, and at L_{Lyα }>10^{43.3} erg s-1 and/or M_{UV}<-21.5 virtually all LAEs are AGN with high ionisation parameters (log U = 0.6 ± 0.5) and with metallicities of ≈0.5 - 1 Z⊙. Those lacking signatures of AGN (40 ± 11 %) have lower ionisation parameters (log U=-3.0^{+1.6}_{-0.9} and log ξion = 25.4 ± 0.2) and are apparently metal-poor sources likely powered by young, dust-poor "maximal" starbursts. Our results show that luminous LAEs at z ˜ 2-3 are a diverse population and that 2 × L^*_{Lyα } and 2 × M_UV^* mark a sharp transition in the nature of LAEs, from star formation dominated to AGN dominated.

[Serum PTH levels as a predictive factor of hypocalcaemia after total thyroidectomy].

PubMed

Díez Alonso, Manuel; Sánchez López, José Daniel; Sánchez-Seco Peña, María Isabel; Ratia Jiménez, Tomás; Arribas Gómez, Ignacio; Rodríguez Pascual, Angel; Martín-Duce, Antonio; Guadalix Hidalgo, Gregorio; Hernández Domínguez, Sara; Granell Vicent, Javier

2009-02-01

Postoperative parathyroid hormone (PTH) levels as a predictor of hypocalcaemia in patients subjected to total thyroidectomy is analyzed. Prospective study involving 67 patients who underwent total thyroidectomy due to a benign disease. Serum PTH and ionised calcium were measured 20 h after surgery. Sensitivity, specificity and predictive values of PTH and ionised calcium levels were calculated to predict clinical and analytical hypocalcaemia. A total of 42 (62.7%) patients developed hypocalcaemia (ionised calcium<0.95 mmol/l), but only 20 (29.9%) presented with symptoms. PTH concentration the day after surgery was significantly lower in the group that developed symptomatic hypocalcaemia (5.57+/-6.4 pg/ml) than in the asymptomatic (21.5+/-15.3 pg/ml) or normocalcaemic (26.8+/-24.9 pg/ml) groups (p=0.001). Taking the value of 13 pg/ml as a cut-off point of PTH levels, sensitivity, specificity, positive predictive value and negative predictive value were 54%, 72%, 76% and 48%, respectively. On the other hand, sensitivity for predicting symptomatic hypocalcaemia was 95% and specificity was 76%. The test showed a high incidence of false positives (11/30, 36%). Negative predictive value was 97% and positive predictive value was 65%. In multivariate analysis, PTH and ionised calcium were the only perioperative factors that showed an independent predictive value as risk indicators of symptomatic hypocalcaemia. Normal PTH levels 20 h after surgery practically rule out the subsequent appearance of hypocalcaemia symptoms. On the other hand, low PTH levels are not necessarily associated to symptomatic hypocalcaemia due to the high number of false positives.

EDDIX--a database of ionisation double differential cross sections.

PubMed

MacGibbon, J H; Emerson, S; Liamsuwan, T; Nikjoo, H

2011-02-01

The use of Monte Carlo track structure is a choice method in biophysical modelling and calculations. To precisely model 3D and 4D tracks, the cross section for the ionisation by an incoming ion, double differential in the outgoing electron energy and angle, is required. However, the double differential cross section cannot be theoretically modelled over the full range of parameters. To address this issue, a database of all available experimental data has been constructed. Currently, the database of Experimental Double Differential Ionisation Cross sections (EDDIX) contains over 1200 digitalised experimentally measured datasets from the 1960s to present date, covering all available ion species (hydrogen to uranium) and all available target species. Double differential cross sections are also presented with the aid of an eight parameter functions fitted to the cross sections. The parameters include projectile species and charge, target nuclear charge and atomic mass, projectile atomic mass and energy, electron energy and deflection angle. It is planned to freely distribute EDDIX and make it available to the radiation research community for use in the analytical and numerical modelling of track structure.

Prediction of intestinal absorption and metabolism of pharmacologically active flavones and flavanones.

PubMed

Serra, H; Mendes, T; Bronze, M R; Simplício, Ana Luísa

2008-04-01

Three glycosilated flavonoids (diosmin, hesperidin and naringin) and respective aglycones were characterized in terms of their apparent ionisation constants and bidirectional permeability using the cellular model Caco-2 as well as the artificial membrane model PAMPA. Ionisation curves were established by capillary electrophoresis. It was confirmed that significant amounts of the aglycones are ionised at physiological pH whereas the glycosides are in the neutral form. Permeation was not detected for the glycosides in either the apical-to-basolateral or basolateral-to-apical directions confirming the need for metabolism before absorption through the intestinal membrane. The aglycones permeated in both directions with apparent permeabilities (P(app)) in the range of 1-8x10(-5) cm/s. The results from both in vitro methods correlated providing some evidence of passive transport; however, the hypothesis of active transport cannot be excluded particularly in the case of diosmetin. Metabolism of the aglycones was detected with the cell model, more extensively when loading in the apical side. Some of the metabolites were identified as glucuronide conjugates by enzymatic hydrolysis.

Explosive detection using a novel dielectric barrier discharge ionisation source for mass spectrometry.

PubMed

Fletcher, Carl; Sleeman, Richard; Luke, John; Luke, Peter; Bradley, James W

2018-03-01

The detection of explosives is of great importance, as is the need for sensitive, reliable techniques that require little or no sample preparation and short run times for high throughput analysis. In this work, a novel ionisation source is presented based on a dielectric barrier discharge (DBD). This not only affects desorption and ionisation but also forms an ionic wind, providing mass transportation of ions towards the mass spectrometer. Furthermore, the design incorporates 2 asymmetric alumina sheets, each containing 3 DBDs, so that a large surface area can be analysed. The DBD operates in ambient air, overcoming the limitation of other plasma-based techniques which typically analyse smaller surface areas and require solvents or gases. A range of explosives across 4 different functional groups was analysed using the DBD with low limits of detection for cyclotrimethylene trinitramine (RDX) (100 pg), pentaerythritol trinitrate (PETN) (100 pg), hexamethylene triperoxide diamide (HMTD) (1 ng), and trinitrotoluene (TNT) (5 ng). Detection was achieved without any sample preparation or the addition of reagents to facilitate adduct formation. Copyright © 2017 John Wiley & Sons, Ltd.

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

NASA Astrophysics Data System (ADS)

Kohanoff, Jorge; McAllister, Maeve; Tribello, Gareth A.; Gu, Bin

2017-09-01

DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts with the interaction of radiation—either photons or swift ions—and the biological medium, which causes electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals. Both of these species can cause damage to biological molecules, in particular DNA. In the long run, this molecular level damage can prevent cells from replicating and can hence lead to cell death. For a long time it was assumed that the main actors in the damage process were the radicals. However, experiments in a seminal paper by the group of Leon Sanche in 2000 showed that low-energy electrons (LEE), such as those generated when ionising biological targets, can also cause bond breaks in biomolecules, and strand breaks in plasmid DNA in particular (Boudaiffa et al 2000 Science 287 1658-60). These results prompted a significant amount of experimental and theoretical work aimed at elucidating the role played by LEE in DNA damage. In this Topical Review we provide a general overview of the problem. We discuss experimental findings and theoretical results hand in hand with the aim of describing the physics and chemistry that occurs during the process of radiation damage, from the initial stages of electronic excitation, through the inelastic propagation of electrons in the medium, the interaction of electrons with DNA, and the chemical end-point effects on DNA. A very important aspect of this discussion is the consideration of a realistic, physiological environment. The role played by the aqueous solution and the amino acids from the histones in chromatin must be considered. Moreover, thermal fluctuations must be incorporated when studying these phenomena. Hence, a special place in this Topical Review is occupied by our recent first-principles molecular dynamics simulations that address the issue of how the environment favours or prevents LEEs from causing damage to DNA. We finish by summarising the conclusions achieved so far, and by suggesting a number of possible directions for further study.

Interactions between low energy electrons and DNA: a perspective from first-principles simulations.

PubMed

Kohanoff, Jorge; McAllister, Maeve; Tribello, Gareth A; Gu, Bin

2017-09-27

DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts with the interaction of radiation-either photons or swift ions-and the biological medium, which causes electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals. Both of these species can cause damage to biological molecules, in particular DNA. In the long run, this molecular level damage can prevent cells from replicating and can hence lead to cell death. For a long time it was assumed that the main actors in the damage process were the radicals. However, experiments in a seminal paper by the group of Leon Sanche in 2000 showed that low-energy electrons (LEE), such as those generated when ionising biological targets, can also cause bond breaks in biomolecules, and strand breaks in plasmid DNA in particular (Boudaiffa et al 2000 Science 287 1658-60). These results prompted a significant amount of experimental and theoretical work aimed at elucidating the role played by LEE in DNA damage. In this Topical Review we provide a general overview of the problem. We discuss experimental findings and theoretical results hand in hand with the aim of describing the physics and chemistry that occurs during the process of radiation damage, from the initial stages of electronic excitation, through the inelastic propagation of electrons in the medium, the interaction of electrons with DNA, and the chemical end-point effects on DNA. A very important aspect of this discussion is the consideration of a realistic, physiological environment. The role played by the aqueous solution and the amino acids from the histones in chromatin must be considered. Moreover, thermal fluctuations must be incorporated when studying these phenomena. Hence, a special place in this Topical Review is occupied by our recent first-principles molecular dynamics simulations that address the issue of how the environment favours or prevents LEEs from causing damage to DNA. We finish by summarising the conclusions achieved so far, and by suggesting a number of possible directions for further study.

Recombination in liquid filled ionisation chambers with multiple charge carrier species: Theoretical and numerical results

NASA Astrophysics Data System (ADS)

Aguiar, P.; González-Castaño, D. M.; Gómez, F.; Pardo-Montero, J.

2014-10-01

Liquid-filled ionisation chambers (LICs) are used in radiotherapy for dosimetry and quality assurance. Volume recombination can be quite important in LICs for moderate dose rates, causing non-linearities in the dose rate response of these detectors, and needs to be corrected for. This effect is usually described with Greening and Boag models for continuous and pulsed radiation respectively. Such models assume that the charge is carried by two different species, positive and negative ions, each of those species with a given mobility. However, LICs operating in non-ultrapure mode can contain different types of electronegative impurities with different mobilities, thus increasing the number of different charge carriers. If this is the case, Greening and Boag models can be no longer valid and need to be reformulated. In this work we present a theoretical and numerical study of volume recombination in parallel-plate LICs with multiple charge carrier species, extending Boag and Greening models. Results from a recent publication that reported three different mobilities in an isooctane-filled LIC have been used to study the effect of extra carrier species on recombination. We have found that in pulsed beams the inclusion of extra mobilities does not affect volume recombination much, a behaviour that was expected because Boag formula for charge collection efficiency does not depend on the mobilities of the charge carriers if the Debye relationship between mobilities and recombination constant holds. This is not the case in continuous radiation, where the presence of extra charge carrier species significantly affects the amount of volume recombination.

The low dose gamma ionising radiation impact upon cooperativity of androgen-specific proteins.

PubMed

Filchenkov, Gennady N; Popoff, Eugene H; Naumov, Alexander D

2014-01-01

The paper deals with effects of the ionising radiation (γ-IR, 0.5 Gy) upon serum testosterone (T), characteristics of testosterone-binding globulin (TeBG) and androgen receptor (AR) in parallel with observation of androgen (A) responsive enzyme activity - hexokinase (HK). The interdependence or relationships of T-levels with parameters of the proteins that provide androgenic regulation are consequently analyzed in post-IR dynamics. The IR-stress adjustment data reveal expediency of TeBG- and AR-cooperativity measurements for more precise assessments of endocrine A-control at appropriate emergencies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Threshold law for positron-atom impact ionisation

NASA Technical Reports Server (NTRS)

Temkin, A.

1982-01-01

The threshold law for ionisation of atoms by positron impact is adduced in analogy with our approach to the electron-atom ionization. It is concluded the Coulomb-dipole region of the potential gives the essential part of the interaction in both cases and leads to the same kind of result: a modulated linear law. An additional process which enters positron ionization is positronium formation in the continuum, but that will not dominate the threshold yield. The result is in sharp contrast to the positron threshold law as recently derived by Klar on the basis of a Wannier-type analysis.

Nanodosimetry of electrons: analysis by experiment and modelling.

PubMed

Bantsar, A; Pszona, S

2015-09-01

Nanodosimetry experiments for high-energy electrons from a (131)I radioactive source interacting with gaseous nitrogen with sizes on a scale equivalent to the mass per area of a segment of DNA and nucleosome are described. The discrete ionisation cluster-size distributions were measured in experiments carried out with the Jet Counter. The experimental results were compared with those obtained by Monte Carlo modelling. The descriptors of radiation damages have been derived from the data obtained from ionisation cluster-size distributions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Using quantum dynamics simulations to follow the competition between charge migration and charge transfer in polyatomic molecules

NASA Astrophysics Data System (ADS)

Spinlove, K. E.; Vacher, M.; Bearpark, M.; Robb, M. A.; Worth, G. A.

2017-01-01

Recent work, particularly by Cederbaum and co-workers, has identified the phenomenon of charge migration, whereby charge flow occurs over a static molecular framework after the creation of an electronic wavepacket. In a real molecule, this charge migration competes with charge transfer, whereby the nuclear motion also results in the re-distribution of charge. To study this competition, quantum dynamics simulations need to be performed. To break the exponential scaling of standard grid-based algorithms, approximate methods need to be developed that are efficient yet able to follow the coupled electronic-nuclear motion of these systems. Using a simple model Hamiltonian based on the ionisation of the allene molecule, the performance of different methods based on Gaussian Wavepackets is demonstrated.

Rac1 as a potential therapeutic target for chemo-radioresistant head and neck squamous cell carcinomas (HNSCC).

PubMed

Skvortsov, S; Dudás, J; Eichberger, P; Witsch-Baumgartner, M; Loeffler-Ragg, J; Pritz, C; Schartinger, V H; Maier, H; Hall, J; Debbage, P; Riechelmann, H; Lukas, P; Skvortsova, I

2014-05-27

In order to improve therapy for HNSCC patients, novel methods to predict and combat local and/or distant tumour relapses are urgently needed. This study has been dedicated to the hypothesis that Rac1, a Rho GTPase, is implicated in HNSCC insensitivity to chemo-radiotherapy resulting in tumour recurrence development. Parental and radiation-resistant (IRR) HNSCC cells were used to support this hypothesis. All cells were investigated for their sensitivity to ionising radiation and cisplatin, Rac1 activity, its intracellular expression and subcellular localisation. Additionally, tumour tissues obtained from 60 HNSCC patients showing different therapy response were evaluated for intratumoral Rac1 expression. Radiation-resistant IRR cells also revealed resistance to cisplatin accompanied by increased expression, activity and trend towards nuclear translocation of Rac1 protein. Chemical inhibition of Rac1 expression and activity resulted in significant improvement of HNSCC sensitivity to ionising radiation and cisplatin. Preclinical results were confirmed in clinical samples. Although Rac1 was poorly presented in normal mucosa, tumour tissues revealed increased Rac1 expression. The most pronounced Rac1 presence was observed in HNSCC patients with poor early or late responses to chemo-radiotherapy. Tissues taken at recurrence were characterised not only by enhanced Rac1 expression but also increased nuclear Rac1 content. Increased expression, activity and subcellular localisation of Rac1 could be associated with lower early response rate and higher risk of tumour recurrences in HNSCC patients and warrants further validation in larger independent studies. Inhibition of Rac1 activity can be useful in overcoming treatment resistance and could be proposed for HNSCC patients with primary or secondary chemo-radioresistance.

The VLT-FLAMES Tarantula Survey. XI. A census of the hot luminous stars and their feedback in 30 Doradus

NASA Astrophysics Data System (ADS)

Doran, E. I.; Crowther, P. A.; de Koter, A.; Evans, C. J.; McEvoy, C.; Walborn, N. R.; Bastian, N.; Bestenlehner, J. M.; Gräfener, G.; Herrero, A.; Köhler, K.; Maíz Apellániz, J.; Najarro, F.; Puls, J.; Sana, H.; Schneider, F. R. N.; Taylor, W. D.; van Loon, J. Th.; Vink, J. S.

2013-10-01

Context. The VLT-FLAMES Tarantula Survey has an extensive view of the copious number of massive stars in the 30 Doradus (30 Dor) star forming region of the Large Magellanic Cloud. These stars play a crucial role in our understanding of the stellar feedback in more distant, unresolved star forming regions. Aims: The first comprehensive census of hot luminous stars in 30 Dor is compiled within a 10 arcmin (150 pc) radius of its central cluster, R136. We investigate the stellar content and spectroscopic completeness of the early type stars. Estimates were made for both the integrated ionising luminosity and stellar wind luminosity. These values were used to re-assess the star formation rate (SFR) of the region and determine the ionising photon escape fraction. Methods: Stars were selected photometrically and combined with the latest spectral classifications. Spectral types were estimated for stars lacking spectroscopy and corrections were made for binary systems, where possible. Stellar calibrations were applied to obtain their physical parameters and wind properties. Their integrated properties were then compared to global observations from ultraviolet (UV) to far-infrared (FIR) imaging as well as the population synthesis code, Starburst99. Results: Our census identified 1145 candidate hot luminous stars within 150 pc of R136 of which >700 were considered to be genuine early type stars and contribute to feedback. We assess the survey to be spectroscopically complete to 85% in the outer regions (>5 pc) but only 35% complete in the region of the R136 cluster, giving a total of 500 hot luminous stars in the census which had spectroscopy. Only 31 were found to be Wolf-Rayet (W-R) or Of/WN stars, but their contribution to the integrated ionising luminosity and wind luminosity was ~40% and ~50%, respectively. Similarly, stars with Minit > 100 M⊙ (mostly H-rich WN stars) also showed high contributions to the global feedback, ~25% in both cases. Such massive stars are not accounted for by the current Starburst99 code, which was found to underestimate the integrated ionising luminosity of R136 by a factor ~2 and the wind luminosity by a factor ~9. The census inferred a SFR for 30 Dor of 0.073 ± 0.04 M⊙ yr-1. This was generally higher than that obtained from some popular SFR calibrations but still showed good consistency with the far-UV luminosity tracer as well as the combined Hα and mid-infrared tracer, but only after correcting for Hα extinction. The global ionising output was also found to exceed that measured from the associated gas and dust, suggesting that ~6+55-6 % of the ionising photons escape the region. Conclusions: When studying the most luminous star forming regions, it is essential to include their most massive stars if one is to determine a reliable energy budget. Photon leakage becomes more likely after including their large contributions to the ionising output. If 30 Dor is typical of other massive star forming regions, estimates of the SFR will be underpredicted if this escape fraction is not accounted for. Based on observations collected at the European Southern Observatory under programme ID 182.D-0222.Appendices are available in electronic form at http://www.aanda.orgFull Tables D1 and D2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A134

Some characteristics of the glutathione cycle revealed by ionising and non-ionising electromagnetic radiation.

PubMed

Holt, J A

1995-10-01

The cyclic reaction of GSH-->GSSG-->GSH (designated R(exp) or R(e)) obeys the three specific features of life by producing energy in exponential quantities relative to time, is in effect irreversible and is inherited from generation to generation. In multicellular life, this reaction produces the energy for mitosis and is kept in controlled inactivity until needed to maintain perfection of form and function by energising mitosis. The immediate control of Re appears to be feedback process-dependent on the concentration of GSSG. Ultra high-frequency electromagnetic radiation of 434 MHz (UHF) will change Re from inactive to active and, in so doing, it causes resonance and/or fluorescence of the glutathione cycle which changes its radiosensitivity. Re is the primary direct target of ionising radiation and produces the energy for mitosis. Clinical observations suggest that, in the normal cell, Re is inactive and is not killed by 3 x 2700 rads or 6 x 1650 rads yet, when active, its sensitivity value (DO) is approximately 160 rads. Using the standard radiobiological equation of response to ionising radiation, it can be deduced that radiosensitive cancers have two or three Re units active per cell and radioresistance increases in proportion to the number of potentially active Re units per cell. Re appears to be the main cause of cancers' increased conductivity of electricity compared with normal tissue. In cancer therapy, UHF is the best radiosensitiser ever discovered (up to two or more decades). Re is also intelligent compared with non-exponential reactions but cannot be the basis of intellectual brain functions which must be based on non-electrical chemical processes.

Deuterium chemistry in the young massive protostellar core NGC 2264 CMM3

NASA Astrophysics Data System (ADS)

Awad, Z.; Shalabiea, O. M.

2018-01-01

In this work we present the first attempt of modelling the deuterium chemistry in the massive young protostellar core NGC 2264 CMM3. We investigated the sensitivity of this chemistry to the physical conditions in its surrounding environment. The results showed that deuteration, in the protostellar gas, is affected by variations in the core density, the amount of gas depletion onto grain surfaces, the CR ionisation rate, but it is insensitive to variations in the H2 ortho-to-para ratio. Our results, also, showed that deuteration is often enhanced in less-dense, partially depleted (<85%), or cores that are exerted to high CR ionisation rates (≥6.5×10^{-17} s^{-1}). However, in NGC 2264 CMM3, decreasing the amount of gas depleted onto grains and enhancing the CR ionisation rate are often overestimating the observed values in the core. The best fit time to observations occurs around (1-5) × 104 yrs for core densities in the range (1-5)×106 cm^{-3} with CR ionisation rate between (1.7-6.5)×10^{-17} s^{-1}. These values are in agreement with the results of the most recent theoretical chemical model of CMM3, and the time range of best fit is, also, in-line with the estimated age of young protostellar objects. We conclude that deuterium chemistry in protostellar cores is: (i) sensitive to variations in the physical conditions in its environment, (ii) insensitive to changes in the H2 ortho-to-para ratio. We also conclude that the core NGC 2264 CMM3 is in its early stages of chemical evolution with an estimated age of (1-5)×104 yrs.

Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry rapid detection of carbapenamase activity in Acinetobacter baumannii isolates.

PubMed

Abouseada, Noha; Raouf, May; El-Attar, Eman; Moez, Pacinte

2017-01-01

Carbapenamase-producing Acinetobacter baumannii are an increasing threat in hospitals and Intensive Care Units. Accurate and rapid detection of carbapenamase producers has a great impact on patient improvement and aids in implementation of infection control measures. In this study, we describe the use of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI TOF MS) to identify carbapenamase-producing A. baumannii isolates in up to 3 h. Isolates and Methods: A total of 50 A. baumannii isolates (of which 39 were carabapenamase producers) were tested using MALDI TOF MS. Isolates were incubated for 3 h with 0.25 mg/ml up to 2 mg/ml of imipenem (IMP) at 37°C. Supernatants were analysed by MALDI TOF to analyse peaks corresponding to IMP (300 Da) and an IMP metabolite (254 Da) using UltrafleXtreme (Bruker Daltonics, Bremen, Germany). All carbapenamase-producing isolates were evidenced by the disappearance or reduction in intensity of the 300 Da peak of IPM and the appearance of a 254 Da peak of the IPM metabolite. In isolates that did not produce carbapenamase, the IPM 300 Da peak remained intact. MALDI TOF is a promising tool in the field of diagnostic microbiology that has the ability to transfer identification and antimicrobial susceptibility testing time from days to hours.

Energy level alignment at planar organic heterojunctions: influence of contact doping and molecular orientation.

PubMed

Opitz, Andreas

2017-04-05

Planar organic heterojunctions are widely used in photovoltaic cells, light-emitting diodes, and bilayer field-effect transistors. The energy level alignment in the devices plays an important role in obtaining the aspired gap arrangement. Additionally, the π-orbital overlap between the involved molecules defines e.g. the charge-separation efficiency in solar cells due to charge-transfer effects. To account for both aspects, direct/inverse photoemission spectroscopy and near edge x-ray absorption fine structure spectroscopy were used to determine the energy level landscape and the molecular orientation at prototypical planar organic heterojunctions. The combined experimental approach results in a comprehensive model for the electronic and morphological characteristics of the interface between the two investigated molecular semiconductors. Following an introduction on heterojunctions used in devices and on energy levels of organic materials, the energy level alignment of planar organic heterojunctions will be discussed. The observed energy landscape is always determined by the individual arrangement between the energy levels of the molecules and the work function of the electrode. This might result in contact doping due to Fermi level pinning at the electrode for donor/acceptor heterojunctions, which also improves the solar cell efficiency. This pinning behaviour can be observed across an unpinned interlayer and results in charge accumulation at the donor/acceptor interface, depending on the transport levels of the respective organic semiconductors. Moreover, molecular orientation will affect the energy levels because of the anisotropy in ionisation energy and electron affinity and is influenced by the structural compatibility of the involved molecules at the heterojunction. High structural compatibility leads to π-orbital stacking between different molecules at a heterojunction, which is of additional interest for photovoltaic active interfaces and for ground-state charge-transfer.

The solar ionisation rate deduced from Ulysses measurements and its implications to interplanetary Lyman alpha-intensity

NASA Technical Reports Server (NTRS)

Summanen, T.; Kyroelae, E.

1995-01-01

We have developed a computer code which can be used to study 3-dimensional and time-dependent effects of the solar cycle on the interplanetary (IP) hydrogen distribution. The code is based on the inverted Monte Carlo simulation. In this work we have modelled the temporal behaviour of the solar ionisation rate. We have assumed that during the most of the time of the solar cycle there is an anisotopic latitudinal structure but right at the solar maximum the anisotropy disappears. The effects of this behaviour will be discussed both in regard to the IP hydrogen distribution and IP Lyman a a-intensity.

Forensic applications of desorption electrospray ionisation mass spectrometry (DESI-MS).

PubMed

Morelato, Marie; Beavis, Alison; Kirkbride, Paul; Roux, Claude

2013-03-10

Desorption electrospray ionisation mass spectrometry (DESI-MS) is an emerging analytical technique that enables in situ mass spectrometric analysis of specimens under ambient conditions. It has been successfully applied to a large range of forensically relevant materials. This review assesses and highlights forensic applications of DESI-MS including the analysis and detection of illicit drugs, explosives, chemical warfare agents, inks and documents, fingermarks, gunshot residues and drugs of abuse in urine and plasma specimens. The minimal specimen preparation required for analysis and the sensitivity of detection achieved offer great advantages, especially in the field of forensic science. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

DOE PAGES

Adams, D.; Adey, D.; Alekou, A.; ...

2013-10-01

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2-2.3 π mm-rad horizontally and 0.6-1.0 π mm-rad vertically, a horizontal dispersion of 90-190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

Non-volatile analysis in fruits by laser resonant ionization spectrometry: application to resveratrol (3,5,4'-trihydroxystilbene) in grapes

NASA Astrophysics Data System (ADS)

Montero, C.; Orea, J. M.; Soledad Muñoz, M.; Lobo, R. F. M.; González Ureña, A.

A laser desorption (LD) coupled with resonance-enhanced multiphoton ionisation (REMPI) and time-of-flight mass spectrometry (TOFMS) technique for non-volatile trace analysis compounds is presented. Essential features are: (a) an enhanced desorption yield due to the mixing of metal powder with the analyte in the sample preparation, (b) a high resolution, great sensitivity and low detection limit due to laser resonant ionisation and mass spectrometry detection. Application to resveratrol content in grapes demonstrated the capability of the analytical method with a sensitivity of 0.2 pg per single laser shot and a detection limit of 5 ppb.

Analysis of a measurement scheme for ultrafast hole dynamics by few femtosecond resolution X-ray pump-probe Auger spectroscopy.

PubMed

Cooper, Bridgette; Kolorenč, Přemysl; Frasinski, Leszek J; Averbukh, Vitali; Marangos, Jon P

2014-01-01

Ultrafast hole dynamics created in molecular systems as a result of sudden ionisation is the focus of much attention in the field of attosecond science. Using the molecule glycine we show through ab initio simulations that the dynamics of a hole, arising from ionisation in the inner valence region, evolves with a timescale appropriate to be measured using X-ray pulses from the current generation of SASE free electron lasers. The examined pump-probe scheme uses X-rays with photon energy below the K edge of carbon (275-280 eV) that will ionise from the inner valence region. A second probe X-ray at the same energy can excite an electron from the core to fill the vacancy in the inner-valence region. The dynamics of the inner valence hole can be tracked by measuring the Auger electrons produced by the subsequent refilling of the core hole as a function of pump-probe delay. We consider the feasibility of the experiment and include numerical simulation to support this analysis. We discuss the potential for all X-ray pump-X-ray probe Auger spectroscopy measurements for tracking hole migration.

EUV-driven ionospheres and electron transport on extrasolar giant planets orbiting active stars

NASA Astrophysics Data System (ADS)

Chadney, J. M.; Galand, M.; Koskinen, T. T.; Miller, S.; Sanz-Forcada, J.; Unruh, Y. C.; Yelle, R. V.

2016-03-01

The composition and structure of the upper atmospheres of extrasolar giant planets (EGPs) are affected by the high-energy spectrum of their host stars from soft X-rays to the extreme ultraviolet (EUV). This emission depends on the activity level of the star, which is primarily determined by its age. In this study, we focus upon EGPs orbiting K- and M-dwarf stars of different ages - ɛ Eridani, AD Leonis, AU Microscopii - and the Sun. X-ray and EUV (XUV) spectra for these stars are constructed using a coronal model. These spectra are used to drive both a thermospheric model and an ionospheric model, providing densities of neutral and ion species. Ionisation - as a result of stellar radiation deposition - is included through photo-ionisation and electron-impact processes. The former is calculated by solving the Lambert-Beer law, while the latter is calculated from a supra-thermal electron transport model. We find that EGP ionospheres at all orbital distances considered (0.1-1 AU) and around all stars selected are dominated by the long-lived H+ ion. In addition, planets with upper atmospheres where H2 is not substantially dissociated (at large orbital distances) have a layer in which H3+ is the major ion at the base of the ionosphere. For fast-rotating planets, densities of short-lived H3+ undergo significant diurnal variations, with the maximum value being driven by the stellar X-ray flux. In contrast, densities of longer-lived H+ show very little day/night variability and the magnitude is driven by the level of stellar EUV flux. The H3+ peak in EGPs with upper atmospheres where H2 is dissociated (orbiting close to their star) under strong stellar illumination is pushed to altitudes below the homopause, where this ion is likely to be destroyed through reactions with heavy species (e.g. hydrocarbons, water). The inclusion of secondary ionisation processes produces significantly enhanced ion and electron densities at altitudes below the main EUV ionisation peak, as compared to models that do not include electron-impact ionisation. We estimate infrared emissions from H3+, and while, in an H/H2/He atmosphere, these are larger from planets orbiting close to more active stars, they still appear too low to be detected with current observatories.

Defects, optical absorption and electron mobility in indium and gallium nitrides

NASA Astrophysics Data System (ADS)

Tansley, T. L.; Egan, R. J.

1993-04-01

We review the experimental evidence for the origin and location of the four native point defects in the wide gap semiconducting indium and gallium nitrides and compare then with experimental predictions. The donor triplets associated with nitrogen vacancies and the deep compensating centres ascribed to the antisite substitutional defects appear to have the greatest effect on macroscopic properties, apparently including the four luminescent bands in GaN. Calculated mobilities in InN and GaN depend principally on ionised impurity and polar-mode phonon scattering. We reconcile these results with experimental data and point out the consequences for improvements in material growth.

Recent advances in terahertz technology for biomedical applications.

PubMed

Sun, Qiushuo; He, Yuezhi; Liu, Kai; Fan, Shuting; Parrott, Edward P J; Pickwell-MacPherson, Emma

2017-06-01

Terahertz instrumentation has improved significantly in recent years such that THz imaging systems have become more affordable and easier to use. THz systems can now be operated by non-THz experts greatly facilitating research into many potential applications. Due to the non-ionising nature of THz light and its high sensitivity to soft tissues, there is an increasing interest in biomedical applications including both in vivo and ex vivo studies. Additionally, research continues into understanding the origin of contrast and how to interpret terahertz biomedical images. This short review highlights some of the recent work in these areas and suggests some future research directions.

XCAMS: The compact 14C accelerator mass spectrometer extended for 10Be and 26Al at GNS Science, New Zealand

NASA Astrophysics Data System (ADS)

Zondervan, A.; Hauser, T. M.; Kaiser, J.; Kitchen, R. L.; Turnbull, J. C.; West, J. G.

2015-10-01

A detailed description is given of the 0.5 MV tandem accelerator mass spectrometry (AMS) system for 10Be, 14C, 26Al, installed in early 2010 at GNS Science, New Zealand. Its design follows that of previously commissioned Compact 14C-only AMS (CAMS) systems based on the Pelletron tandem accelerator. The only basic departure from that design is an extension of the rare-isotope achromat with a 45° magnet and a two-anode gas-ionisation detector, to provide additional filtering for 10Be. Realised performance of the three AMS modes is discussed in terms of acceptance-test scores, 14C Poisson and non-Poisson errors, and 10Be detection limit and sensitivity. Operational details and hardware improvements, such as 10Be beam transport and particle detector setup, are highlighted. Statistics of repeat measurements of all graphitised 14C calibration cathodes since start-up show that 91% of their total uncertainty values are less than 0.3%, indicating that the rare-isotope beamline extension has not affected precision of 14C measurement. For 10Be, the limit of detection in terms of the isotopic abundance ratio 10Be/9Be is 6 × 10-15 at at-1 and the total efficiency of counting atoms in the sample cathode is 1/8500 (0.012%).

Is an Accreting Binary Black Hole Precursor Driving the Ionisation Structure and its Kinematics in the Carafe?

NASA Astrophysics Data System (ADS)

Shastri, Prajval

2017-09-01

We seek to test the hypothesis that radiatively efficient accretion onto the central supermassive black holes (SMBHs) of two merging galaxies drive the emission-line structure and kinematics that we see in the ROSAT-detected Carafe. We have confirmed the presence of two compact sources with LINER-type spectra, which coincide with two compact radio sources that we detect. We have obtained the emission-line structure and kinematics of the Carafe with an optical IFU mosaic. We demonstrate that the proposed 35ksec ACIS imaging will yield both the soft and hard X-ray photons that we need to definitively distinguish between the following hypotheses: that the driver of the system is a pair of accreting SMBH, or that the hot extended gas in the Carafe is shock-excited by two compact star bursts.

Identification and structural characterisation of triterpene saponins from the root of Ardisia mamillata Hance by HPLC-ESI-QTOF-MS/MS.

PubMed

Zhang, Er-Fei; Ling, Yun; Yin, Zi; Zhang, Qing

2018-04-01

Triterpene saponins in medicinal plants attract scientific attentions for their structural diversity and significant bioactivities. In this work, a high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) method is used to rapidly separate and identify triterpene saponins from the extract of Ardisia mamillata Hance (AMH). In the full scan mass spectrum, the accurate determination of molecular formula is obtained by the predominant ion [M + HCOO] - in negative ion mode. As a result, 30 triterpene saponins are identified or tentatively identified in the plant extract. Of these, 17 triterpene saponins are new compounds. In conclusion, the HPLC-ESI-QTOF-MS/MS is an efficient technique to separate and identify triterpene saponins in complex matrices of medicinal plant.

The influence of continuum radiation fields on hydrogen radio recombination lines

NASA Astrophysics Data System (ADS)

Prozesky, Andri; Smits, Derck P.

2018-05-01

Calculations of hydrogen departure coefficients using a model with the angular momentum quantum levels resolved that includes the effects of external radiation fields are presented. The stimulating processes are important at radio frequencies and can influence level populations. New numerical techniques with a solid mathematical basis have been incorporated into the model to ensure convergence of the solution. Our results differ from previous results by up to 20 per cent. A direct solver with a similar accuracy but more efficient than the iterative method is used to evaluate the influence of continuum radiation on the hydrogen population structure. The effects on departure coefficients of continuum radiation from dust, the cosmic microwave background, the stellar ionising radiation, and free-free radiation are quantified. Tables of emission and absorption coefficients for interpreting observed radio recombination lines are provided.

Evaluation of novel derivatisation reagents for the analysis of oxysterols

PubMed Central

Crick, Peter J.; Aponte, Jennifer; Bentley, T. William; Matthews, Ian; Wang, Yuqin; Griffiths, William J.

2014-01-01

Oxysterols are oxidised forms of cholesterol that are intermediates in the synthesis of bile acids and steroid hormones. They are also ligands to nuclear and G protein-coupled receptors. Analysis of oxysterols in biological systems is challenging due to their low abundance coupled with their lack of a strong chromophore and poor ionisation characteristics in mass spectrometry (MS). We have previously used enzyme-assisted derivatisation for sterol analysis (EADSA) to identify and quantitate oxysterols in biological samples. This technique relies on tagging sterols with the Girard P reagent to introduce a charged quaternary ammonium group. Here, we have compared several modified Girard-like reagents and show that the permanent charge is vital for efficient MSn fragmentation. However, we find that the reagent can be extended to include sites for potential stable isotope labels without a loss of performance. PMID:24525124

Space science applications for conducting polymer particles: synthetic mimics for cosmic dust and micrometeorites.

PubMed

Fielding, Lee A; Hillier, Jon K; Burchell, Mark J; Armes, Steven P

2015-12-11

Over the last decade or so, a range of polypyrrole-based particles have been designed and evaluated for space science applications. This electrically conductive polymer enables such particles to efficiently acquire surface charge, which in turn allows their acceleration up to the hypervelocity regime (>1 km s(-1)) using a Van de Graaff accelerator. Either organic latex (e.g. polystyrene or poly(methyl methacrylate)) or various inorganic materials (such as silica, olivine or pyrrhotite) can be coated with polypyrrole; these core-shell particles are useful mimics for understanding the hypervelocity impact ionisation behaviour of micro-meteorites (a.k.a. cosmic dust). Impacts on metal targets at relatively low hypervelocities (<10 km s(-1)) generate ionic plasma composed mainly of molecular fragments, whereas higher hypervelocities (>10 km s(-1)) generate predominately atomic species, since many more chemical bonds are cleaved if the particles impinge with higher kinetic energy. Such fundamental studies are relevant to the calibration of the cosmic dust analyser (CDA) onboard the Cassini spacecraft, which was designed to determine the chemical composition of Saturn's dust rings. Inspired by volcanism observed for one of the Jupiter's moons (Io), polypyrrole-coated sulfur-rich latexes have also been designed to help space scientists understand ionisation spectra originating from sulfur-rich dust particles. Finally, relatively large (20 μm diameter) polypyrrole-coated polystyrene latexes have proven to be useful for understanding the extent of thermal ablation of organic projectiles when fired at ultralow density aerogel targets at up to 6.1 km s(-1) using a Light Gas Gun. In this case, the sacrificial polypyrrole overlayer simply provides a sensitive spectroscopic signature (rather than a conductive overlayer), and the scientific findings have important implications for the detection of organic dust grains during the Stardust space mission.

Feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) networking in university hospitals in Brussels.

PubMed

Martiny, D; Cremagnani, P; Gaillard, A; Miendje Deyi, V Y; Mascart, G; Ebraert, A; Attalibi, S; Dediste, A; Vandenberg, O

2014-05-01

The mutualisation of analytical platforms might be used to address rising healthcare costs. Our study aimed to evaluate the feasibility of networking a unique matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) system for common use in several university hospitals in Brussels, Belgium. During a one-month period, 1,055 successive bacterial isolates from the Brugmann University Hospital were identified on-site using conventional techniques; these same isolates were also identified using a MALDI-TOF MS system at the Porte de Hal Laboratory by sending target plates and identification projects via transportation and the INFECTIO_MALDI software (Infopartner, Nancy, France), respectively. The occurrence of transmission problems (<2 %) and human errors (<1 %) suggested that the system was sufficiently robust to be implemented in a network. With a median time-to-identification of 5 h and 11 min (78 min, min-max: 154-547), MALDI-TOF MS networking always provided a faster identification result than conventional techniques, except when chromogenic culture media and oxidase tests were used (p < 0.0001). However, the limited clinical benefits of the chromogenic culture media do not support their extra cost. Our financial analysis also suggested that MALDI-TOF MS networking could lead to substantial annual cost savings. MALDI-TOF MS networking presents many advantages, and few conventional techniques (optochin and oxidase tests) are required to ensure the same quality in patient care from the distant laboratory. Nevertheless, such networking should not be considered unless there is a reorganisation of workflow, efficient communication between teams, qualified technologists and a reliable IT department and helpdesk to manage potential connectivity problems.

Monitoring of estrogens, pesticides and bisphenol A in natural waters and drinking water treatment plants by solid-phase extraction-liquid chromatography-mass spectrometry.

PubMed

Rodriguez-Mozaz, Sara; de Alda, Maria J López; Barceló, Damià

2004-08-06

A multi-residue analytical method has been developed for the determination of various classes of selected endocrine disruptors. This method allows the simultaneous extraction and quantification of different estrogens (estradiol, estrone, estriol, estradiol-17-glucuronide, estradiol diacetate, estrone-3-sulfate, ethynyl estradiol and diethylstilbestrol), pesticides (atrazine, simazine, desethylatrazine, isoproturon and diuron), and bisphenol A in natural waters. In the method developed, 500 ml of water are preconcentrated on LiChrolut RP-18 cartridges. Further analysis is carried out by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionisation (APCI) in the positive ion mode for determination of pesticides and electrospray in the negative ionisation mode for determination of estrogens and bisphenol A. Recoveries for most compounds were between 90 and 119%, except for bisphenol A (81%) and diethylstilbestrol (70%), with relative standard deviations below 20%. Limits of detection ranged between 2 and 15 ng/l. The method was used to study the occurrence of the selected pollutants in surface and groundwater used for abstraction of drinking water in a waterworks and to evaluate the removal efficiency of the different water treatments applied. Water samples from the river, the aquifer, and after each treatment stage (sand filtration, ozonation, activated carbon filtration and post-chlorination) were taken monthly from February to August of 2002. The presence in river water of atrazine, simazine, diuron and bisphenol A were relatively frequent at concentrations usually below 0.1 microg/l. Lower levels, below 0.02 microg/l, were usual for isoproturon. Estrone-3-sulfate and estrone were detected occasionally in the river. Most of the compounds were completely removed during the water treatment, especially after activated carbon filtration.

A new measurement of the half-life of (166m)Ho.

PubMed

Nedjadi, Y; Bailat, C; Caffari, Y; Froidevaux, P; Wastiel, C; Kivel, N; Guenther-Leopold, I; Triscone, G; Jaquenod, F; Bochud, F

2012-09-01

The work presented here is a new and precise measurement of the half-life of (166m)Ho by determining the activity concentration, using an ionisation chamber calibrated for this nuclide, and measuring the number of (166m)Ho atoms using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Since the isotope (166)Er interferes with the mass spectrometric measurement, Er has to be eliminated from the (166m)Ho radioactive solution. The elimination was achieved using ion-exchange chromatography with the cation exchange resin Dowex AG 50W-X8 and 2-Hydroxybutanoic acid as the mobile phase. After a first transit through the chromatographic column, the purified (166m)Ho eluate was spiked with natural Er to get a resulting Er isotopic composition close to that of natural Er at better than 99.5%, and then it underwent two further separations to eliminate the Er. The activity concentration of this Er-free radioactive (166m)Ho solution was measured in our reference ionisation chamber calibrated for this nuclide by means of the 4πβ(PC)-γ and 4πβ(PS)-4πγ coincidence techniques and integral counting with a well-type NaI(Tl) detector and Monte Carlo efficiencies. An aliquot of this standardized solution was sent to the Paul Scherrer Institute (PSI) for mass concentration determination using an isotope dilution MC-ICP-MS approach. The mass concentration of (166m)Ho in this solution was determined with 0.25% relative standard uncertainty. This value was corroborated by two other independent measurements. The new half-life of (166m)Ho, 1132.6(39) years (k=1), is compatible with the value determined in 1965, but is 5.6% shorter and about 43 times more precise. Copyright © 2012 Elsevier Ltd. All rights reserved.

Stress echocardiography in contemporary clinical cardiology: practical considerations and accreditation

PubMed Central

Shah, Benoy N; MacNab, Anita; Lynch, Jane; Hampson, Reinette; Senior, Roxy; Steeds, Richard P

2018-01-01

Stress echocardiography is a widely utilised test in patients with known or suspected coronary artery disease (CAD), valvular heart disease and cardiomyopathies. Its advantages include the ubiquitous availability of echocardiography, lack of ionising radiation, choice of physiological or pharmacological stressors, good diagnostic accuracy and robust supporting evidence base. SE has evolved significantly as a technique over the past three decades and has benefitted considerably from improvements in overall image quality (superior resolution), machine technology (e.g. digital cine-loop acquisition and side-by-side image display) and development of second-generation ultrasound contrast agents that have improved reader confidence and diagnostic accuracy. The purpose of this article is to review the breadth of SE in contemporary clinical cardiology and discuss the recently launched British Society of Echocardiography (BSE) Stress Echocardiography accreditation scheme. PMID:29358185

The use of ionisation chambers for dose rate measurements at industrial irradiation plants

NASA Astrophysics Data System (ADS)

Sephton, J. P.; Sharpe, P. H. G.; Chu, R. D. H.

2002-03-01

The use of ionisation chambers to measure dose rate at industrial irradiation plants has been studied as part of a wider project on real time dosimetry. The characteristics required of such a chamber are discussed. These include the ability to withstand operation at high cumulative doses (up to 5 MGy) and dose rates of up to about 150 kGy h -1. Other desirable features are water equivalence and immunity to environmental conditions such as temperature, pressure and humidity. A number of chambers have been assessed experimentally and a suitable chamber selected. The dosimetric characteristics of the chosen chamber have been assessed by comparison with absorbed dose measurements made using chemical dosimeters.

Plasma concentrations of parathyroid hormone-related protein in dogs with potential disorders of calcium metabolism.

PubMed

Mellanby, R J; Craig, R; Evans, H; Herrtage, M E

2006-12-16

The plasma concentrations of total calcium, ionised calcium, albumin, parathyroid hormone and parathyroid hormone-related protein (PTHrp) were measured in 25 dogs with lymphoma, nine dogs with primary hyperparathyroidism and seven dogs with adenocarcinoma of the apocrine gland of the anal sac. Plasma total calcium, ionised calcium, albumin and parathyroid hormone-related protein were measured in 18 clinically normal control dogs. The concentration of PTHrp was high in 12 of the 14 dogs that were hypercalcaemic because of an underlying malignancy but was within the reference range in all the control dogs, in the 17 normocalcaemic dogs with lymphoma and in the seven dogs which were hypercalcaemic because of a parathyroid adenoma.

The combined effects of high-energy shock waves and ionising radiation on a human bladder cancer cell line.

PubMed

Fickweiler, S; Steinbach, P; Wörle, K; Hofstädter, F

1996-01-01

The effects of high-energy shock waves (HESW) generated by an experimental Siemens lithotripter in combination with 137Cs gamma-rays were examined in vitro. Proliferation after treatment of immobilised pellets of either single cells or multicellular spheroids of the bladder cancer cell line RT4 was determined using colony-forming assays and cell cycle analysis. Surviving and cell cycle fractions were calculated for each shock wave and radiation application mode separately, and for sequential combination in different successions for the purpose of characterizing the interaction of both treatment modalities. Combination of HESW and ionising radiation turned out to act additively or slightly supra-additively on both biologic models.

Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing.

PubMed

Adam, T W; Clairotte, M; Streibel, T; Elsasser, M; Pommeres, A; Manfredi, U; Carriero, M; Martini, G; Sklorz, M; Krasenbrink, A; Astorga, C; Zimmermann, R

2012-07-01

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated.

Measurement of inelastic cross sections for low-energy electron scattering from DNA bases.

PubMed

Michaud, Marc; Bazin, Marc; Sanche, Léon

2012-01-01

To determine experimentally the absolute cross sections (CS) to deposit various amount of energies into DNA bases by low-energy electron (LEE) impact. Electron energy loss (EEL) spectra of DNA bases were recorded for different LEE impact energies on the molecules deposited at very low coverage on an inert argon (Ar) substrate. Following their normalisation to the effective incident electron current and molecular surface number density, the EEL spectra were then fitted with multiple Gaussian functions in order to delimit the various excitation energy regions. The CS to excite a molecule into its various excitation modes were finally obtained from computing the area under the corresponding Gaussians. The EEL spectra and absolute CS for the electronic excitations of pyrimidine and the DNA bases thymine, adenine, and cytosine by electron impacts below 18 eV were reported for the molecules deposited at about monolayer coverage on a solid Ar substrate. The CS for electronic excitations of DNA bases by LEE impact were found to lie within the 10(216) to 10(218) cm(2) range. The large value of the total ionisation CS indicated that ionisation of DNA bases by LEE is an important dissipative process via which ionising radiation degrades and is absorbed in DNA.

Measurement of inelastic cross sections for low-energy electron scattering from DNA bases

PubMed Central

Michaud, Marc; Bazin, Marc.; Sanche, Léon

2013-01-01

Purpose Determine experimentally the absolute cross sections (CS) to deposit various amount of energies into DNA bases by low-energy electron (LEE) impact. Materials and methods Electron energy loss (EEL) spectra of DNA bases are recorded for different LEE impact energies on the molecules deposited at very low coverage on an inert argon (Ar) substrate. Following their normalisation to the effective incident electron current and molecular surface number density, the EEL spectra are then fitted with multiple Gaussian functions in order to delimit the various excitation energy regions. The CS to excite a molecule into its various excitation modes are finally obtained from computing the area under the corresponding Gaussians. Results The EEL spectra and absolute CS for the electronic excitations of pyrimidine and the DNA bases thymine, adenine, and cytosine by electron impacts below 18 eV are reported for the molecules deposited at about monolayer coverage on a solid Ar substrate. Conclusions The CS for electronic excitations of DNA bases by LEE impact are found to lie within the 10−16 – 10−18 cm2 range. The large value of the total ionisation CS indicates that ionisation of DNA bases by LEE is an important dissipative process via which ionising radiation degrades and is absorbed in DNA. PMID:21615242

Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

PubMed Central

Rudd, David; Benkendorff, Kirsten; Voelcker, Nicolas H.

2015-01-01

Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples. PMID:25786067

An important step forward in continuous spectroscopic imaging of ionising radiations using ASICs

NASA Astrophysics Data System (ADS)

Fessler, P.; Coffin, J.; Eberlé, H.; de Raad Iseli, C.; Hilt, B.; Huss, D.; Krummenacher, F.; Lutz, J. R.; Prévot, G.; Renouprez, A.; Sigward, M. H.; Schwaller, B.; Voltolini, C.

1999-01-01

Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus, the use of on-line corrections of the inevitable dispersion of characteristics between the large number of electronic channels of the detection system, shall be precluded. Without claiming to achieve ultimate noise levels, the work described is focused on how to prevent good individual acquisition channel noise performance from being totally destroyed by the dispersion between channels without introducing dead times. With this goal, we developed an automatic charge amplifier output voltage offset compensation system which operates regardless of the cause of the offset (detector or electronic). The main performances of the system are the following: the input equivalent noise charge is 190 e rms (input non connected, peaking time 500 ns), the highest gain is 255 mV/fC, the peaking time is adjustable between 200 ns and 2 μs and the power consumption is 10 mW per channel. The agreement between experimental data and theoretical simulation results is excellent.

Accumulation and dissipation of positive charges induced on a PMMA build-up cap of an ionisation chamber by (60)Co gamma-ray irradiation.

PubMed

Morishita, Y; Takata, N

2013-07-01

The signal current from an ionisation chamber with a PMMA build-up cap decreases with irradiation time due to electric fields produced by positive charges induced on the cap. In the present study, it was confirmed that the signal current decreases faster for irradiation using narrower (60)Co gamma-ray beams. This is because the number of secondary electrons that are emitted from surrounding materials and penetrate the build-up cap is smaller in a narrower gamma-ray beam, so that fewer positive charges are neutralised. The ionisation chamber was first subjected to continuous gamma-ray irradiation for 24 h, following which it was irradiated with shorter periodic gamma-ray bursts while measuring the current signal. This allowed the coefficients of positive charge accumulation and dissipation to be determined. It was found that the dissipation coefficient has a large constant value during gamma-ray irradiation and decreases asymptotically to a small value after irradiation is stopped. From the coefficients, the minimum signal current was calculated, which is the value when accumulation and dissipation balance each other under continuous irradiation. The time required for the signal current to recover following irradiation was also calculated.

Electron impact ionisation cross sections of iron oxides

NASA Astrophysics Data System (ADS)

Huber, Stefan E.; Mauracher, Andreas; Sukuba, Ivan; Urban, Jan; Maihom, Thana; Probst, Michael

2017-12-01

We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9 . 96 × 10-16 cm2 located at 59-72 eV and 5.06 to 14.32 × 10-16 cm2 located at 85-108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4-1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80308-2.

The X-ray spectra of the black hole candidate 4U 1630-47 during its 2012 outburst

NASA Astrophysics Data System (ADS)

Wang, Y.; Mendez, M.

2015-07-01

Diaz Trigo et al. (2013) reported the detection of three Doppler-shifted emission lines arising from baryonic matter in the jet of 4U 1630-47 during its 2012 outburst. Here we propose an alternative model that, without the need of the lines from the jet, and with less free parameters, fits the same data equally well. In our model we allow the abundances of S and Fe in the interstellar medium to vary; the best-fitting values are, respectively, 1.5 and 0.5 times solar, consistent with recent findings. Our model also includes a moderately broad emission line and a narrow absorption line due to highly ionised Fe. (These lines are also present in the other observations of this source during the 2012 outburst.) This model fits well all the XMM-Newton observations of this source, both in burst and timing mode. In addition to the components that we fitted to the burst-mode data, the timing-mode observations show several absorption features due to ionised Fe and Ni, which reveal the presence of a highly-ionised absorber close to the source. Our model also fits well the burst-mode data using the most recent calibration files (March 2015), whereas the model from Diaz Trigo et al. does not.

A simple model for molecular hydrogen chemistry coupled to radiation hydrodynamics

NASA Astrophysics Data System (ADS)

Nickerson, Sarah; Teyssier, Romain; Rosdahl, Joakim

2018-06-01

We introduce non-equilibrium molecular hydrogen chemistry into the radiation-hydrodynamics code RAMSES-RT. This is an adaptive mesh refinement grid code with radiation hydrodynamics that couples the thermal chemistry of hydrogen and helium to moment-based radiative transfer with the Eddington tensor closure model. The H2 physics that we include are formation on dust grains, gas phase formation, formation by three-body collisions, collisional destruction, photodissociation, photoionisation, cosmic ray ionisation and self-shielding. In particular, we implement the first model for H2 self-shielding that is tied locally to moment-based radiative transfer by enhancing photo-destruction. This self-shielding from Lyman-Werner line overlap is critical to H2 formation and gas cooling. We can now track the non-equilibrium evolution of molecular, atomic, and ionised hydrogen species with their corresponding dissociating and ionising photon groups. Over a series of tests we show that our model works well compared to specialised photodissociation region codes. We successfully reproduce the transition depth between molecular and atomic hydrogen, molecular cooling of the gas, and a realistic Strömgren sphere embedded in a molecular medium. In this paper we focus on test cases to demonstrate the validity of our model on small scales. Our ultimate goal is to implement this in large-scale galactic simulations.

Impact ionisation mass spectrometry of platinum-coated olivine and magnesite-dominated cosmic dust analogues

NASA Astrophysics Data System (ADS)

Hillier, Jon K.; Sternovsky, Z.; Kempf, S.; Trieloff, M.; Guglielmino, M.; Postberg, F.; Price, M. C.

2018-07-01

Impact ionisation mass spectrometry enables the composition of cosmic dust grains to be determined in situ by spacecraft-based instrumentation. The proportion of molecular ions in the impact plasma is a function of the impact velocity, making laboratory calibration vital for the interpretation of the mass spectra, particularly at the low velocities typical of lunar or asteroid encounters. Here we present an analysis of laboratory impact ionisation mass spectra from primarily low (<15 km s-1) velocity impacts of both olivine and magnesite-dominated particles onto the SUrface Dust Mass Analyzer (SUDA) laboratory mass spectrometer. The cation mass spectra show characteristic peaks due to their constituent elements, with Mg, Al, Si, C, Ca, O and Fe frequently present. Contaminant species from the conductive coating process (B, Na, K, C, Pt) also occur, at varying frequencies. Possible saponite or talc inclusions in the magnesite particles are revealed by the presence of Si, Fe, Ca and Al in the magnesite mass spectra. Magnesium is clearly present at the lowest impact velocities (3 km s-1), at which alkali metals were presumed to dominate. Peaks attributed to very minor amounts of water or hydroxyl present in the grains are also seen at low velocities in both cation and anion mass spectra, demonstrating the feasibility of impact ionisation mass spectrometry in identifying hydrated or hydrous minerals, during very low velocity encounters or with very low abundances of water or hydroxy groups, in the impinging grains. Velocity thresholds for the reliable identification of the major elements within the magnesite and olivine cation spectra are presented. Additionally, relative sensitivity factors for Mg (5.1), Fe (1.5) and O (0.6) with respect to Si, in the olivine particles, at impact speeds >19 km s-1, were found to be very similar to those previously determined for orthopyroxene-dominated particles, despite different target and projectile materials. This confirms that quantitative analyses of mineral dust grain composition in space is viable despite initially poorly-constrained mineralogy.

AGN feedback on molecular gas reservoirs in quasars at z 2.4

NASA Astrophysics Data System (ADS)

Carniani, S.; Marconi, A.; Maiolino, R.; Feruglio, C.; Brusa, M.; Cresci, G.; Cano-Díaz, M.; Cicone, C.; Balmaverde, B.; Fiore, F.; Ferrara, A.; Gallerani, S.; La Franca, F.; Mainieri, V.; Mannucci, F.; Netzer, H.; Piconcelli, E.; Sani, E.; Schneider, R.; Shemmer, O.; Testi, L.

2017-09-01

We present new ALMA observations aimed at mapping molecular gas reservoirs through the CO(3-2) transition in three quasars at z ≃ 2.4, LBQS 0109+0213, 2QZ J002830.4-281706, and [HB89] 0329-385. Previous [Oiii]λ5007 observations of these quasars showed evidence for ionised outflows quenching star formation in their host galaxies. Systemic CO(3-2) emission has been detected only in one quasar, LBQS 0109+0213, where the CO(3-2) emission is spatially anti-correlated with the ionised outflow, suggesting that most of the molecular gas may have been dispersed or heated in the region swept by the outflow. In all three sources, including the one detected in CO, our constraints on the molecular gas mass indicate a significantly reduced reservoir compared to main-sequence galaxies at the same redshift, supporting a negative feedback scenario. In the quasar 2QZ J002830.4-281706, we tentatively detect an emission line blob blue-shifted by v - 2000 km s-1 with respect to the galaxy systemic velocity and spatially offset by 0.2'' (1.7 kpc) with respect to the ALMA continuum peak. Interestingly, such emission feature is coincident in both velocity and space with the ionised outflow as seen in [Oiii]λ5007. This tentative detection must be confirmed with deeper observations but, if real, it could represent the molecular counterpart of the ionised gas outflow driven by the Active Galactic Nucleus (AGN). Finally, in all ALMA maps we detect the presence of serendipitous line emitters within a projected distance 160 kpc from the quasars. By identifying these features with the CO(3-2) transition, we find that the serendipitous line emitters would be located within | Δv | < 500 km s-1 from the quasars, hence suggesting an overdensity of galaxies in two out of three quasars.

Alpha particle spectroscopy using FNTD and SIM super-resolution microscopy.

PubMed

Kouwenberg, J J M; Kremers, G J; Slotman, J A; Wolterbeek, H T; Houtsmuller, A B; Denkova, A G; Bos, A J J

2018-06-01

Structured illumination microscopy (SIM) for the imaging of alpha particle tracks in fluorescent nuclear track detectors (FNTD) was evaluated and compared to confocal laser scanning microscopy (CLSM). FNTDs were irradiated with an external alpha source and imaged using both methodologies. SIM imaging resulted in improved resolution, without increase in scan time. Alpha particle energy estimation based on the track length, direction and intensity produced results in good agreement with the expected alpha particle energy distribution. A pronounced difference was seen in the spatial scattering of alpha particles in the detectors, where SIM showed an almost 50% reduction compared to CLSM. The improved resolution of SIM allows for more detailed studies of the tracks induced by ionising particles. The combination of SIM and FNTDs for alpha radiation paves the way for affordable and fast alpha spectroscopy and dosimetry. © 2018 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.

Kinetic modelling of the optically stimulated conversion of peaks 5a and 5 to peak 4 in LiF:Mg,Ti (TLD-100).

PubMed

Weizman, Y; Horowitz, Y S; Oster, L

2002-01-01

The TC/LC conversion model for peaks 4, 5a and 5 in LiF:Mg,Ti (TLD-100) has been studied by solution of the coupled differential equations describing the charge carrier traffic following optical stimulation. Aspects of the model investigated were (i) the two-component exponential decay of the composite peak 5 TL intensity following the bleach, (ii) the role of retrapping during bleaching, (iii) the hole nature of peak 4 and (iv) the conversion of peak 5a traps to peak 4 traps. The high conversion efficiency is naturally explained due to the absence of conduction band competitive mechanisms in the optical ionisation of the electron in the e-h occupied structure corresponding to peak 5a and thereby leading to the hole-only occupied TC/LC leading to peak 4.

The first bump-bonded pixel detectors on CVD diamond

NASA Astrophysics Data System (ADS)

Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P. F.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Mishina, M.; Oh, A.; Palmieri, V. G.; Pan, L. S.; Peitz, A.; Pernicka, M.; Pirollo, S.; Polesello, P.; Pretzl, K.; Re, V.; Riester, J. L.; Roe, S.; Roff, D.; Rudge, A.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Steuerer, J.; Stone, R.; Tapper, R. J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Turchetta, R.; Vittone, E.; Wagner, A.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Zeuner, W.; Ziock, H.; Zoeller, M.; Charles, E.; Ciocio, A.; Dao, K.; Einsweiler, K.; Fasching, D.; Gilchriese, M.; Joshi, A.; Kleinfelder, S.; Milgrome, O.; Palaio, N.; Richardson, J.; Sinervo, P.; Zizka, G.; RD42 Collaboration

1999-11-01

Diamond is a nearly ideal material for detecting ionising radiation. Its outstanding radiation hardness, fast charge collection and low leakage current allow it to be used in high radiation environments. These characteristics make diamond sensors particularly appealing for use in the next generation of pixel detectors. Over the last year, the RD42 collaboration has worked with several groups that have developed pixel readout electronics in order to optimise diamond sensors for bump-bonding. This effort resulted in an operational diamond pixel sensor that was tested in a pion beam. We demonstrate that greater than 98% of the channels were successfully bump-bonded and functioning. The device shows good overall hit efficiency as well as clear spatial hit correlation to tracks measured in a silicon reference telescope. A position resolution of 14.8 μm was observed, consistent with expectations given the detector pitch.

Magnetic monopole search with the MoEDAL test trapping detector

NASA Astrophysics Data System (ADS)

Katre, Akshay

2016-11-01

IMoEDAL is designed to search for monopoles produced in high-energy Large Hadron Collider (LHC) collisions, based on two complementary techniques: nucleartrack detectors for high-ionisation signatures and other highly ionising avatars of new physics, and trapping volumes for direct magnetic charge measurements with a superconducting magnetometer. The MoEDAL test trapping detector array deployed in 2012, consisting of over 600 aluminium samples, was analysed and found to be consistent with zero trapped magnetic charge. Stopping acceptances are obtained from a simulation of monopole propagation in matter for a range of charges and masses, allowing to set modelindependent and model-dependent limits on monopole production cross sections. Multiples of the fundamental Dirac magnetic charge are probed for the first time at the LHC.

End-group characterisation of poly(propylene glycol)s by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS).

PubMed

Jackson, Anthony T; Slade, Susan E; Thalassinos, Konstantinos; Scrivens, James H

2008-10-01

The end-group functionalisation of a series of poly(propylene glycol)s has been characterised by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS). A series of peaks with mass-to-charge ratios that are close to that of the precursor ion were used to generate information on the end-group functionalities of the poly(propylene glycol)s. Fragment ions resulting from losses of both of the end groups were noted from some of the samples. An example is presented of how software can be used to significantly reduce the length of time involved in data interpretation (which is typically the most time-consuming part of the analysis).

Biophysical damage in metallo-enzyme and mammalian cells by Cu-K X-rays and radioisotopes

NASA Astrophysics Data System (ADS)

Younis, Abdul-Redha Sahib

In the fields of radiobiology and nuclear medicine there is considerable interest in the important role played by Auger electron cascades caused by inner-shell ionisation in realistic risk. It is necessary to quantify this risk when radionuclides are used on a routine basis as investigative, diagnostic and radiotherapeutic tools, whether the applications involve incorporated electron capture radionuclides or K-shell ionisation of selected stable nuclides by X-rays, as in "photon activation therapy". Relevant published survival data on biological damage caused by the internal emitters 125I, 77Br, 3H, 33P, 131I and 32P which are incorporated into the DNA of mammalian cells, bacteria (E. Coli) and bacteriophages have been collected and the results re-analysed in terms of the parameters of a new damage model to determine an inactivation cross-section for each internal emitter. These quality parameters are the absolute specification of radiation quality and are compared with cross-sections similarly determined for the effects of external radiations from heavy charged particles and photons (chapter 2). The inactivation probabilities obtained for the nuclides 125I, 77Br and 3H extend over a wide range of values depending on the type of nuclide and its distribution, the type of sensitive target and its shape and distribution, and the environmental temperature during both irradiation and post-irradiation incubation. The higher values approach those determined for heavy charged particles with the same mean free path for primary ionisation, and are an order of magnitude larger than would be expected for external irradiation with photon generated electrons. The results for 33P, 131I and 32P nuclides are appreciably smaller than that expected for external irradiation since the long range electrons dissipate most of their energy out of the sensitive target. A theoretical equation for X-ray production by accelerated electrons incident on a thick target has been revised by including factors to compensate for backscattering, direct and indirect ionisation, attenuation in the target and the incident angle of electrons (chapter 3). An electron accelerator X-ray machine capable of delivering monoenergetic photons up to 4.8 gray/sec exposure dose rate from four different targets has been designed, constructed and tested (chapter 4) The biophysical mechanisms of direct and indirect radiation action has also been studied using the metallo-enzyme dihydroorotic dehydrogenase. The enzyme was irradiated both in dry state and in solution at different concentrations and at different dose rates using monoenergetic Cu-K photons from our X-ray machine. A technique was developed whereby it was possible to isolate and quantify each type of radiation action (chapter 5). The inactivation of the enzyme in both solution and in dry state was found to be a single-hit/single-target process. It was also found that in solution the inactivation of the enzyme was dose-rate-and concentration-dependent with efficiency of radical inactivation has an exponential dependence on dose-rate and the inverse of the enzyme concentration. A new model for the inactivation of the enzyme has been suggested and its parameters, namely direct and indirect cross-sections, geometrical cross-section, saturated concentration constant, root mean square diffusion constant, mean free path of radicals absorption, life time and G value of radical production, have been determined. It is expected that this model can be generalised to suit other enzymes (chapter 6).

Determining energy balance in the flaring chromosphere from oxygen V line ratios

NASA Astrophysics Data System (ADS)

Graham, D. R.; Fletcher, L.; Labrosse, N.

2015-12-01

Context. The impulsive phase of solar flares is a time of rapid energy deposition and heating in the lower solar atmosphere, leading to changes in the temperature and density structure of the region. Aims: We use an O v density diagnostic formed from the λ192 /λ248 line ratio, provided by the Hinode/EIS instrument, to determine the density of flare footpoint plasma at O v formation temperatures of ~2.5 × 105 K, giving a constraint on the properties of the heated transition region. Methods: Hinode/EIS rasters from 2 small flare events in December 2007 were used. Raster images were co-aligned to identify and establish the footpoint pixels, multiple-component Gaussian line fitting of the spectra was carried out to isolate the density diagnostic pair, and the density was calculated for several footpoint areas. The assumptions of equilibrium ionisation and optically-thin radiation for the O v lines used were assessed and found to be acceptable. For one of the events, properties of the electron distribution were deduced from earlier RHESSI hard X-ray observations. These were used to calculate the plasma heating rate delivered by an electron beam for 2 semi-empirical atmospheres under collisional thick-target assumptions. The radiative loss rate for this plasma was also calculated for comparison with possible energy input mechanisms. Results: Electron number densities of up to 1011.9 cm-3 were measured during the flare impulsive phase using the O v λ192 /λ248 diagnostic ratio. The heating rate delivered by an electron beam was found to exceed the radiative losses at this density, corresponding to a height of 450 km, and when assuming a completely ionised target atmosphere far exceed the losses but at a height of 1450-1600 km. A chromospheric thickness of 70-700 km was found to be required to balance a conductive input to the O v-emitting region with radiative losses. Conclusions: Electron densities have been observed in footpoint sources at transition region temperatures, comparable to previous results but with improved spatial information. The observed densities can be explained by heating of the chromosphere by collisional electrons, with O v formed at heights of 450-1600 km above the photosphere, depending on the atmospheric ionisation fraction.

H2O2/TiO2 photocatalytic oxidation of metol. Identification of intermediates and reaction pathways.

PubMed

Aceituno, Mónica; Stalikas, Constantine D; Lunar, Loreto; Rubio, Soledad; Pérez-Bendito, Dolores

2002-08-01

The applicability of H2O2 to increase the efficiency of TiO2 photocatalytic degradations was investigated. The photographic developer metol [N-methyl-p-aminophenol] that does not adsorb on the surface of TiO2 particulates was used as a model for this purpose. It was proved that metol was mineralised under oxidation with H2O2/TiO2/UV through different thermal and photochemical reactions. Identification of intermediates by both HPLC-electron impact-MS and HPLC-electrospray ionisation-MS helped to elucidate the role of H2O2 and TiO2 in the degradation process and to establish degradation pathways. Intermediates yielded were partially oxygenated aromatic species and dimers, which were amenable to oxidation. The optimal degradation conditions found for mineralisation were 0.4 M H2O2, 5 mg/ml TiO2, pH 9 and irradiation centred at 360 nm (4.9 mW/cm2). The use of oxidants opens an interesting medium to the treatment of effluents containing a diversity of organics since they increase substantially the efficiency of TiO2 photocatalytic degradations.

Evaluation of novel derivatisation reagents for the analysis of oxysterols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crick, Peter J., E-mail: p.j.crick@swansea.ac.uk; Aponte, Jennifer; Bentley, T. William

2014-04-11

Graphical abstract: - Highlights: • New derivatisation reagents for LC–MS analysis of oxysterols. • New reagents based on Girard P give high ion-currents and informative LC–MS{sup n} spectra. • Permanent charge is vital for efficient MS{sup n} fragmentation. • New reagents offer greater scope for incorporation of isotope labels. - Abstract: Oxysterols are oxidised forms of cholesterol that are intermediates in the synthesis of bile acids and steroid hormones. They are also ligands to nuclear and G protein-coupled receptors. Analysis of oxysterols in biological systems is challenging due to their low abundance coupled with their lack of a strong chromophoremore » and poor ionisation characteristics in mass spectrometry (MS). We have previously used enzyme-assisted derivatisation for sterol analysis (EADSA) to identify and quantitate oxysterols in biological samples. This technique relies on tagging sterols with the Girard P reagent to introduce a charged quaternary ammonium group. Here, we have compared several modified Girard-like reagents and show that the permanent charge is vital for efficient MS{sup n} fragmentation. However, we find that the reagent can be extended to include sites for potential stable isotope labels without a loss of performance.« less

Radiation-induced cardiovascular effects

NASA Astrophysics Data System (ADS)

Tapio, Soile

Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

X-ray studies on crystalline complexes involving amino acids and peptides. XXXII. Effect of chirality on ionisation state, stoichiometry and aggregation in the complexes of oxalic acid with DL- and L-lysine.

PubMed

Venkatraman, J; Prabu, M M; Vijayan, M

1997-08-01

Crystals of the oxalic acid complex of DL-lysine (triclinic P1; a = 5.540(1), b = 10.764(2), c = 12.056(2) A, alpha = 77.8(1), beta = 80.6(1), gamma = 75.6(1).; R = 4.7% for 2023 observed reflections) contain lysine and semioxalate ions in the 1:1 ratio, whereas the ratio of lysine and semioxalate/oxalate ions is 2:3 in the crystals of the L-lysine complex (monoclinic P2(1); alpha = 4.906(1), b = 20.145(4), c = 12.455(1) A, beta = 92.5(1).; R = 4.4% for 1494 observed reflections). The amino acid molecule in the L-lysine complex has an unusual ionisation state with positively charged alpha- and side-chain amino groups and a neutral carboxyl group. The unlike molecules aggregate into separate alternating layers in the DL-lysine complex in a manner similar to that observed in several of the amino acid complexes. The L-lysine complex exhibits a new aggregation pattern which cannot be easily explained in terms of planar features, thus emphasizing the fundamental dependence of aggregation on molecular characteristics. Despite the differences in stoichiometry, ionisation state and long-range aggregation patterns, the basic element of aggregation in the two complexes exhibits considerable similarity.

Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

NASA Astrophysics Data System (ADS)

Hambsch, F.-J.; Salvador-Castiñeira, P.; Oberstedt, S.; Göök, A.; Billnert, R.

2016-06-01

In recent years JRC-IRMM has been investigating fission cross-sections of 240,242Pu in the fast-neutron energy range relevant for innovative reactor systems and requested in the High Priority Request List (HPRL) of the OECD/Nuclear Energy Agency (NEA). In addition to that, prompt neutron multiplicities are being investigated for the major isotopes 235U, 239Pu in the neutron-resonance region using a newly developed scintillation detector array (SCINTIA) and an innovative modification of the Frisch-grid ionisation chamber for fission-fragment detection. These data are highly relevant for improved neutron data evaluation and requested by the OECD/Working Party on Evaluation Cooperation (WPEC). Thirdly, also prompt fission γ-ray emission is investigated using highly efficient lanthanide-halide detectors with superior timing resolution. Again, those data are requested in the HPRL for major actinides to solve open questions on an under-prediction of decay heat in nuclear reactors. The information on prompt fission neutron and γ-ray emission is crucial for benchmarking nuclear models to study the de-excitation process of neutron-rich fission fragments. Information on γ-ray emission probabilities is also useful in decommissioning exercises on damaged nuclear power plants like Fukushima Daiichi to which JRC-IRMM is contributing. The results on the 240,242Pu fission cross section, 235U prompt neutron multiplicity in the resonance region and correlations with fission fragments and prompt γ-ray emission for several isotopes will be presented and put into perspective.

Ionisation density effects following optical excitation in LiF:Mg, Ti (TLD-100).

PubMed

Weiss, D; Horowitz, Y; Oster, L

2007-01-01

The TL signal following 5 eV photon excitation of previously irradiated and readout material has been studied as a function of ionisation density and various experimental parameters: (i) maximum temperature of the first readout; (ii) photon fluence; (iii) photon energy and (iv) beta ray dose. Following alpha particle irradiation, the ratio of the second-readout to first-readout TL signal, epsilon(alpha,) has been found to be 10-20 times higher than that following beta irradiation, indicative of the possibility of using the double ratio epsilon(alpha)/epsilon(beta) as a mixed-field discriminator. The beginning of an attempt to explain this unusual effect is offered in the framework of the track structure theory and kinetic modelling of the beta ray dose-response of the first and second readouts.

Direct atmospheric pressure chemical ionisation ion trap mass spectrometry for aroma analysis: Speed, sensitivity and resolution of isobaric compounds

NASA Astrophysics Data System (ADS)

Jublot, Lionel; Linforth, Robert S. T.; Taylor, Andrew J.

2005-06-01

Atmospheric pressure chemical ionisation (APCI) sources were developed for real time analysis of volatile release from foods using an ion trap (IT) mass spectrometer (MS). Key objectives were spectral simplicity (minimal fragmentation), response time and signal to noise ratio. The benefits of APCI-IT-MS were assessed by comparing the performance for in vivo and headspace analyses with that obtained using APCI coupled to a quadrupole mass analyser. Using MS-MS, direct APCI-IT-MS was able to differentiate mixtures of some C6 and terpene isobaric aroma compounds. Resolution could be achieved for some compounds by monitoring specific secondary ions. Direct resolution was also achieved with two of the three isobaric compounds released from chocolate with time as the sample was eaten.

Radiation protection and safety in medical use of ionising radiation in Republic of Bulgaria--harmonization of the national legislation with Euratom directives.

PubMed

Ingilizova, K; Vassileva, J; Rupova, I; Pavlova, A

2005-01-01

From February 2002 to November 2003 the National Centre of Radiobiology and Radiation Protection conducted a PHARE twinning project 'Radiation Protection and Safety at Medical Use of Ionising Radiation'. The main purposes of the project were the harmonization of Bulgarian legislation in the field of radiation protection with EC Directives 96/29 and 97/43 Euratom, and the establishment of appropriate institutional infrastructure and administrative framework for their implementation. This paper presents the main results of the project: elaboration of Ordinance for Protection of Individuals from Medical Exposure; performance of a national survey of distribution of patient doses in diagnostic radiology and of administered activities in nuclear medicine and establishment of national reference levels for the most common diagnostic procedures.

Rapid screening of illicit additives in weight loss dietary supplements with desorption corona beam ionisation (DCBI) mass spectrometry.

PubMed

Wang, H; Wu, Y; Zhao, Y; Sun, W; Ding, L; Guo, B; Chen, B

2012-08-01

Desorption corona beam ionisation (DCBI), the relatively novel ambient mass spectrometry (MS) technique, was utilised to screen for illicit additives in weight-loss food. The five usually abused chemicals - fenfluramine, N-di-desmethyl sibutramine, N-mono-desmethyl sibutramine, sibutramine and phenolphthalein - were detected with the proposed DCBI-MS method. Fast single-sample and high-throughput analysis was demonstrated. Semi-quantification was accomplished based on peak areas in the ion chromatograms. Four illicit additives were identified and semi-quantified in commercial samples. As there was no tedious sample pre-treatment compared with conventional HPLC methods, high-throughput analysis was achieved with DCBI. The results proved that DCBI-MS is a powerful tool for the rapid screening of illicit additives in weight-loss dietary supplements.

[Specific and non-specific electromagnetic irradiation effects on biological objects].

PubMed

Berezovs'kyĭ, V Ia

2003-01-01

There are the pecularities of the biophysical influence of the ultraviolet, light and infra-red irradiation in connection with their frequent and energetic characteristics. The specific resonant and non-specific heating effects are educed (distinguished). [table: see text] It is shown that the radial area of electromagnetic spectrum corresponding to the non-ionising. Sun irradiation, contains the evolutionary fixed molecular mechanisms of the energy acception activizing biochemical and biophysical metabolic reactions. The living beings, deprived of heliofugal influences (cave and deep-watered specimen objects) reached only the primitive development stages. The dosed wage of the non-ionising radiation generators in the clinic medicine promotes the restoration of the self sanogenic mechanisms and deficit restoration of the natural influences caused by the contemporary human being's mode of life changes.

Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

NASA Astrophysics Data System (ADS)

Taborda, A.; Desbrée, A.; Carvalho, A.; Chaves, P. C.; Reis, M. A.

2016-08-01

Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 103 barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing 57Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

2015-08-15

In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si{sub 3}N{sub 4} membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energymore » measurement.« less

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: On the possibility of pumping Xe2* lasers and VUV lamps in the afterglow of a background-electron multiplication wave

NASA Astrophysics Data System (ADS)

Boichenko, Aleksandr M.; Yakovlenko, Sergei I.

2006-12-01

It was shown earlier that the ionisation propagation in a gas at about the atmospheric pressure may proceed due to the multiplication of the existing electrons with a low background density rather than the transfer of electrons or photons. We consider the feasibility of using the plasma produced in the afterglow of this background-electron multiplication wave for pumping plasma lasers (in particular, Xe2* xenon excimer lasers) as well as excilamps. Simulations show that it is possible to achieve the laser effect at λapprox172 nm as well as to substantially improve the peak specific power of the spontaneous radiation of xenon lamps.

Multiwavelength campaign on Mrk 509. XI. Reverberation of the Fe Kα line

NASA Astrophysics Data System (ADS)

Ponti, G.; Cappi, M.; Costantini, E.; Bianchi, S.; Kaastra, J. S.; De Marco, B.; Fender, R. P.; Petrucci, P.-O.; Kriss, G. A.; Steenbrugge, K. C.; Arav, N.; Behar, E.; Branduardi-Raymont, G.; Dadina, M.; Ebrero, J.; Lubiński, P.; Mehdipour, M.; Paltani, S.; Pinto, C.; Tombesi, F.

2013-01-01

Context. We report on a detailed study of the Fe K emission/absorption complex in the nearby, bright Seyfert 1 galaxy Mrk 509. The study is part of an extensive XMM-Newton monitoring consisting of 10 pointings (~60 ks each) about once every 4 days, and includes a reanalysis of previous XMM-Newton and Chandra observations. Aims: We aim at understanding the origin and location of the Fe K emission and absorption regions. Methods: We combine the results of time-resolved spectral analysis on both short and long time-scales including model-independent rms spectra. Results: Mrk 509 shows a clear (EW = 58 ± 4 eV) neutral Fe Kα emission line that can be decomposed into a narrow (σ = 0.027 keV) component (found in the Chandra HETG data) plus a resolved (σ = 0.22 keV) component. We find the first successful measurement of a linear correlation between the intensity of the resolved line component and the 3-10 keV flux variations on time scales of years down to a few days. The Fe Kα reverberates the hard X-ray continuum without any measurable lag, suggesting that the region producing the resolved Fe Kα component is located within a few light days to a week (r ≲ 103rg) from the black hole (BH). The lack of a redshifted wing in the line poses a lower limit of ≥40 rg for its distance from the BH. The Fe Kα could thus be emitted from the inner regions of the BLR, i.e. within the ~80 light days indicated by the Hβ line measurements. In addition to these two neutral Fe Kα components, we confirm the detection of weak (EW ~ 8-20 eV) ionised Fe K emission. This ionised line can be modelled with either a blend of two narrow Fe xxv and Fe xxvi emission lines (possibly produced by scattering from distant material) or with a single relativistic line produced, in an ionised disc, down to a few rg from the BH. In the latter interpretation, the presence of an ionised standard α-disc, down to a few rg, is consistent with the source high Eddington ratio. Finally, we observe a weakening/disappearing of the medium- and high-velocity high-ionisation Fe K wind features found in previous XMM-Newton observations. Conclusions: This campaign has made the first reverberation measurement of the resolved component of the Fe Kα line possible, from which we can infer a location for the bulk of its emission at a distance of r ~ 40-1000 rg from the BH.

Ionising radiation-free whole-body MRI versus (18)F-fluorodeoxyglucose PET/CT scans for children and young adults with cancer: a prospective, non-randomised, single-centre study.

PubMed

Klenk, Christopher; Gawande, Rakhee; Uslu, Lebriz; Khurana, Aman; Qiu, Deqiang; Quon, Andrew; Donig, Jessica; Rosenberg, Jarrett; Luna-Fineman, Sandra; Moseley, Michael; Daldrup-Link, Heike E

2014-03-01

Imaging tests are essential for staging of children with cancer. However, CT and radiotracer-based imaging procedures are associated with substantial exposure to ionising radiation and risk of secondary cancer development later in life. Our aim was to create a highly effective, clinically feasible, ionising radiation-free staging method based on whole-body diffusion-weighted MRI and the iron supplement ferumoxytol, used off-label as a contrast agent. We compared whole-body diffusion-weighted MRI with standard clinical (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT scans in children and young adults with malignant lymphomas and sarcomas. Whole-body diffusion-weighted magnetic resonance images were generated by coregistration of colour-encoded ferumoxytol-enhanced whole-body diffusion-weighted MRI scans for tumour detection with ferumoxytol-enhanced T1-weighted MRI scans for anatomical orientation, similar to the concept of integrated (18)F-FDG PET/CT scans. Tumour staging results were compared using Cohen's κ statistics. Histopathology and follow-up imaging served as the standard of reference. Data was assessed in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT01542879. 22 of 23 recruited patients were analysed because one patient discontinued before completion of the whole-body scan. Mean exposure to ionising radiation was 12·5 mSv (SD 4·1) for (18)F-FDG PET/CT compared with zero for whole-body diffusion-weighted MRI. (18)F-FDG PET/CT detected 163 of 174 malignant lesions at 1325 anatomical regions and whole-body diffusion-weighted MRI detected 158. Comparing (18)F-FDG PET/CT to whole-body diffusion-weighted MRI, sensitivities were 93·7% (95% CI 89·0-96·8) versus 90·8% (85·5-94·7); specificities 97·7% (95% CI 96·7-98·5) versus 99·5% (98·9-99·8); and diagnostic accuracies 97·2% (93·6-99·4) versus 98·3% (97·4-99·2). Tumour staging results showed very good agreement between both imaging modalities with a κ of 0·93 (0·81-1·00). No adverse events after administration of ferumoxytol were recorded. Ferumoxytol-enhanced whole-body diffusion-weighted MRI could be an alternative to (18)F-FDG PET/CT for staging of children and young adults with cancer that is free of ionising radiation. This new imaging test might help to prevent long-term side-effects from radiographic staging procedures. Thrasher Research Fund and Clinical Health Research Institute at Stanford University. Copyright © 2014 Elsevier Ltd. All rights reserved.

Deployment of the FIGAERO Iodide Time of flight (ToF)-Chemical ionisation mass spectrometer (CIMS) using X-ray ionisation in Manaus

NASA Astrophysics Data System (ADS)

Bannan, T.; Bacak, A.; Priestley, M.; Adelstein, E.; Worrall, S.; Artaxo, P.; Carbone, S.; Topping, D. O.; Allan, J. D.; Coe, H.; Percival, C.

2017-12-01

Here the deployment of the The Filter Inlet for Gases and AEROsols (FIGAERO) coupled with the Aerodyne High Resolution (HR)-Time of flight (ToF)-Chemical ionisation mass spectrometer (CIMS) in Manaus is presented. This project utilised the Tofwerk X-ray ionisation source in the tropical rainforest in close proximity to Manaus, Brazil, at the ZF2 measurement site. The FIGAERO is a filter based technique that provides simultaneous molecular information of both the gas and particle phase. When analysing particles that have been collected the evolution of the MS signals from different compounds change independently as a function of temperature; creating a thermogram that is m/z specific. The temperature for which the desorbed signal shows a maximum for each compound has been used previously to extract vapour pressure information in laboratory characterisatio. Krieger et al. (2017) defined the homologous series of polyethylene glycols as a series of compounds that showed a very good agreement over a wide range of atmospherically relevant vapour pressures between different experimental setups. PEG samples therefore provide an ideal bench mark for characterising individual FIGAERO inlets to give vapour pressure information essential for partitioning characterisation. The PEG calibration curve has been used to validate vapour pressure measurements in a well-defined single component bases and in simple chamber experiments, results of which are presented. With a high reactivity and large ubiquitous global source, isoprene has a profound effect upon atmospheric chemistry and composition. Despite this there are still significant gaps in the understanding of the processes that lead to isoprene derived secondary organic aerosol (SOA). This project aims to provide insights into the role of isoprene in the mechanisms of production of SOA and its importance in the particulate mass budgets in the tropics and the fundamental chemical processes. The volatility and composition of isoprene oxidation products is shown for numerous isoprene oxidation products identified and concentrations of the C5 oxidation products in the low ppt level are reported. Total organic compounds measured in the particle phase with the FIGAERO are compared with the organic ACSM showing a good agreement throughout.

The cause of spatial structure in solar He I 1083 nm multiplet images

NASA Astrophysics Data System (ADS)

Leenaarts, Jorrit; Golding, Thomas; Carlsson, Mats; Libbrecht, Tine; Joshi, Jayant

2016-10-01

Context. The He I 1083 nm is a powerful diagnostic for inferring properties of the upper solar chromosphere, in particular for the magnetic field. The basic formation of the line in one-dimensional models is well understood, but the influence of the complex three-dimensional structure of the chromosphere and corona has however never been investigated. This structure must play an essential role because images taken in He I 1083 nm show structures with widths down to 100 km. Aims: We aim to understand the effect of the three-dimensional temperature and density structure in the solar atmosphere on the formation of the He I 1083 nm line. Methods: We solved the non-LTE radiative transfer problem assuming statistical equilibrium for a simple nine-level helium atom that nevertheless captures all essential physics. As a model atmosphere we used a snapshot from a 3D radiation-MHD simulation computed with the Bifrost code. Ionising radiation from the corona was self-consistently taken into account. Results: The emergent intensity in the He I 1083 nm is set by the source function and the opacity in the upper chromosphere. The former is dominated by scattering of photospheric radiation and does not vary much with spatial location. The latter is determined by the photonionisation rate in the He I ground state continuum, as well as the electron density in the chromosphere. The spatial variation of the flux of ionising radiation is caused by the spatially-structured emissivity of the ionising photons from material at T ≈ 100 kK in the transition region. The hotter coronal material produces more ionising photons, but the resulting radiation field is smooth and does not lead to small-scale variation of the UV flux. The corrugation of the transition region further increases the spatial variation of the amount of UV radiation in the chromosphere. Finally we find that variations in the chromospheric electron density also cause strong variation in He I 1083 nm opacity. We compare our findings to observations using SST, IRIS and SDO/AIA data. A movie associated to Fig. 4 is available at http://www.aanda.org

Characterisation of soy isoflavones and screening for novel malonyl glycosides using high-performance liquid chromatography-electrospray ionisation-mass spectrometry.

PubMed

Gu, L; Gu, W

2001-01-01

HPLC combined with electrospray ionisation (ESI)-MS and photodiode array detection has been employed to study the isoflavone components of soy. All of the known soy isoflavones separated by HPLC were identified and characterised, and three novel isoflavones were detected and screened out. These minor isoflavones were deduced to be isomers of 6"-O-malonyl isoflavone glycosides, based on the ESI-MS and UV data, in which the malonyl group is attached at a position other than the 6" position of the glycosyl moiety of the molecule. These novel malonyl glycosides are as thermally labile as the 6"-O-malonyl glycosides, being converted into known isoflavone glycosides after heating in aqueous ethanol. The advantages of HPLC-ESI-MS in detection of novel isoflavones from plant extracts are reviewed.

Radiochromic 3D Detectors

NASA Astrophysics Data System (ADS)

Oldham, Mark

2015-01-01

Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and the lack of requirement for development of the colour change. In a radiochromic material, the colour change arises direct from ionising interactions affecting dye molecules, without requiring any latent chemical, optical or thermal development, with important implications for increased accuracy and convenience. It is only relatively recently however, that 3D radiochromic dosimetry has become possible. In this article we review recent developments and the current state-of-the-art of 3D radiochromic dosimetry, and the potential for a more comprehensive solution for the verification of complex radiation therapy treatments, and 3D dose measurement in general.

Tools to discover anionic and nonionic polyfluorinated alkyl surfactants by liquid chromatography electrospray ionisation mass spectrometry.

PubMed

Trier, Xenia; Granby, Kit; Christensen, Jan H

2011-10-07

A tiered approach is proposed for the discovery of unknown anionic and nonionic polyfluorinated alkyl surfactants (PFASs) by reversed phase ultra high performance liquid chromatography (UHPLC)--negative electrospray ionisation--quadrupole time of flight mass spectrometry (UHPLC-ESI(-)-QTOF-MS). The chromatographic separation, ionisation and detection of PFASs mixtures, was achieved at high pH (pH=9.7) with NH(4)OH as additive. To distinguish PFASs from other chemicals we used the characteristic negative mass defects of PFASs, their specific losses of 20 Da (HF) and the presence of series of chromatographic peaks, belonging to homologues series with m/z of n×50 Da (CF(2)) or n×100 Da (CF(2)CF(2)). The elemental composition of the precursor ions were deducted from the accurate m/z values of the deprotonated molecules [M-H](-). In case of in-source fragmentation, the presence of dimers, e.g. [M(2)-H](-) and adduct ions such as [M-H+solvent](-) and [(M-H)(M-H+Na)(n)](-) were used to confirm the identity of the precursor ions. In relation to quantification of PFASs, we discuss how their surfactancy influence the ESI processes, challenge their handling in solution and choices of precursor-to-product ions for MSMS of e.g., structural PFAS isomers. The method has been used to discover PFASs in industrial blends and in extracts from food contact materials. Copyright © 2011 Elsevier B.V. All rights reserved.

Rationale and design of the NO-PARTY trial: near-zero fluoroscopic exposure during catheter ablation of supraventricular arrhythmias in young patients.

PubMed

Casella, Michela; Dello Russo, Antonio; Pelargonio, Gemma; Bongiorni, Maria Grazia; Del Greco, Maurizio; Piacenti, Marcello; Andreassi, Maria Grazia; Santangeli, Pasquale; Bartoletti, Stefano; Moltrasio, Massimo; Fassini, Gaetano; Marini, Massimiliano; Di Cori, Andrea; Di Biase, Luigi; Fiorentini, Cesare; Zecchi, Paolo; Natale, Andrea; Picano, Eugenio; Tondo, Claudio

2012-10-01

Radiofrequency catheter ablation is the mainstay of therapy for supraventricular tachyarrhythmias. Conventional radiofrequency catheter ablation requires the use of fluoroscopy, thus exposing patients to ionising radiation. The feasibility and safety of non-fluoroscopic radiofrequency catheter ablation has been recently reported in a wide range of supraventricular tachyarrhythmias using the EnSite NavX™ mapping system. The NO-PARTY is a multi-centre, randomised controlled trial designed to test the hypothesis that catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX™ mapping system results in a clinically significant reduction in exposure to ionising radiation compared with conventional catheter ablation. The study will randomise 210 patients undergoing catheter ablation of supraventricular tachyarrhythmias to either a conventional ablation technique or one guided by the EnSite NavX™ mapping system. The primary end-point is the reduction of the radiation dose to the patient. Secondary end-points include procedural success, reduction of the radiation dose to the operator, and a cost-effectiveness analysis. In a subgroup of patients, we will also evaluate the radiobiological effectiveness of dose reduction by assessing acute chromosomal DNA damage in peripheral blood lymphocytes. NO-PARTY will determine whether radiofrequency catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX™ mapping system is a suitable and cost-effective approach to achieve a clinically significant reduction in ionising radiation exposure for both patient and operator.

Controlling plasma properties under differing degrees of electronegativity using odd harmonic dual frequency excitation

NASA Astrophysics Data System (ADS)

Gibson, Andrew R.; Gans, Timo

2017-11-01

The charged particle dynamics in low-pressure oxygen plasmas excited by odd harmonic dual frequency waveforms (low frequency of 13.56 MHz and high frequency of 40.68 MHz) are investigated using a one-dimensional numerical simulation in regimes of both low and high electronegativity. In the low electronegativity regime, the time and space averaged electron and negative ion densities are approximately equal and plasma sustainment is dominated by ionisation at the sheath expansion for all combinations of low and high frequency and the phase shift between them. In the high electronegativity regime, the negative ion density is a factor of 15-20 greater than the low electronegativity cases. In these cases, plasma sustainment is dominated by ionisation inside the bulk plasma and at the collapsing sheath edge when the contribution of the high frequency to the overall voltage waveform is low. As the high frequency component contribution to the waveform increases, sheath expansion ionisation begins to dominate. It is found that the control of the average voltage drop across the plasma sheath and the average ion flux to the powered electrode are similar in both regimes of electronegativity, despite the differing electron dynamics using the considered dual frequency approach. This offers potential for similar control of ion dynamics under a range of process conditions, independent of the electronegativity. This is in contrast to ion control offered by electrically asymmetric waveforms where the relationship between the ion flux and ion bombardment energy is dependent upon the electronegativity.

Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering

NASA Astrophysics Data System (ADS)

Stark, C. R.; Diver, D. A.

2018-04-01

Context. In contemporary sub-stellar model atmospheres, dust growth occurs through neutral gas-phase surface chemistry. Recently, there has been a growing body of theoretical and observational evidence suggesting that ionisation processes can also occur. As a result, atmospheres are populated by regions composed of plasma, gas and dust, and the consequent influence of plasma processes on dust evolution is enhanced. Aim. This paper aims to introduce a new model of dust growth and destruction in sub-stellar atmospheres via plasma deposition and plasma sputtering. Methods: Using example sub-stellar atmospheres from DRIFT-PHOENIX, we have compared plasma deposition and sputtering timescales to those from neutral gas-phase surface chemistry to ascertain their regimes of influence. We calculated the plasma sputtering yield and discuss the circumstances where plasma sputtering dominates over deposition. Results: Within the highest dust density cloud regions, plasma deposition and sputtering dominates over neutral gas-phase surface chemistry if the degree of ionisation is ≳10-4. Loosely bound grains with surface binding energies of the order of 0.1-1 eV are susceptible to destruction through plasma sputtering for feasible degrees of ionisation and electron temperatures; whereas, strong crystalline grains with binding energies of the order 10 eV are resistant to sputtering. Conclusions: The mathematical framework outlined sets the foundation for the inclusion of plasma deposition and plasma sputtering in global dust cloud formation models of sub-stellar atmospheres.

Characterisation of ionisation chambers for a mixed radiation field and investigation of their suitability as radiation monitors for the LHC.

PubMed

Theis, C; Forkel-Wirth, D; Perrin, D; Roesler, S; Vincke, H

2005-01-01

Monitoring of the radiation environment is one of the key tasks in operating a high-energy accelerator such as the Large Hadron Collider (LHC). The radiation fields consist of neutrons, charged hadrons as well as photons and electrons with energy spectra extending from those of thermal neutrons up to several hundreds of GeV. The requirements for measuring the dose equivalent in such a field are different from standard uses and it is thus necessary to investigate the response of monitoring devices thoroughly before the implementation of a monitoring system can be conducted. For the LHC, it is currently foreseen to install argon- and hydrogen-filled high-pressure ionisation chambers as radiation monitors of mixed fields. So far their response to these fields was poorly understood and, therefore, further investigation was necessary to prove that they can serve their function well enough. In this study, ionisation chambers of type IG5 (Centronic Ltd) were characterised by simulating their response functions by means of detailed FLUKA calculations as well as by calibration measurements for photons and neutrons at fixed energies. The latter results were used to obtain a better understanding and validation of the FLUKA simulations. Tests were also conducted at the CERF facility at CERN in order to compare the results with simulations of the response in a mixed radiation field. It is demonstrated that these detectors can be characterised sufficiently enough to serve their function as radiation monitors for the LHC.

Etude des mécanismes d'ionisation de H{2}O par interaction He^{*}(2 ^1S, 2 ^3S)/Ne^{*}(^3P{0}, ^3P{2})+H{2}O

NASA Astrophysics Data System (ADS)

Le Nadan, André; Sinou, Guillaume; Tuffin, Firmin

1993-06-01

Experimental observations of Penning ionisation of H{2}O by the helium metastables 21S and 23S and by the neon metastables ^3P{0} and ^3P{2} are reported. The kinetic energies of the ions created during the collision process (both parent and fragment) are analysed. Certain particularities of the experimental results are explained by involving the hypothesis of transfers of vibrational energy to kinetic energy. Furthermore, the forms of the energy distributions of the fragment ions are explained by th predissociation of the ^2B{2} state of H{2}O+. Nous avons étudié l'ionisation Penning de H{2}O par des métastables 21S et 23S de l'hélium, ainsi que ^3P{0} et ^3P{2} du néon. Nous avons analysé l'énergie cinétique des ions créés au cours de la collision (parents et fragments). Afin d'interpréter certaines particularités expérimentales, l'hypothèse de transferts d'énergie de vibration en énergie cinétique est proposées. Par ailleurs, les caractéristiques des distributions en énergie des ions fragments sont expliquées par la prédissociation de l'état ^2B{2} de H{2}O+.

Isochoric heating of low Z solid targets with sub 10 fs laser pulses

NASA Astrophysics Data System (ADS)

Osterholz, Jens

2004-11-01

The investigation of high density plasmas plays an important role for astrophysics, inertial confinement fusion and x-ray lasers. Therefore the generation of dense plasmas with ultra-intense laser pulses is a field of enormous topical interest. An upper limit of the maximum plasma density that can be achieved with this method, however, occurs due to the formation of a preplasma and the expansion of the plasma during the interaction [1,2]. Here we describe a novel approach that is based on a laser system that generates sub 10 fs pulses with a low prepulse energy. Isochoric heating is demonstrated with small Z solid targets. Time integrated XUV spectroscopy is used to investigate K-shell emission from the plasma. In the spectra, only the Ly α and He α lines are observed, whereas transitions from orbitals with principal quantum numbers n > 2 are not present. This series limit is explained by pressure ionisation in the dense plasma. The XUV spectra were simulated by two different models [3]. The first calculates the effect of pressure ionisation and the second calculates the line intensity ratios. Preliminary calculations suggest that the plasma density of the emitting region is close to solid density with an electron temperature of about 100eV. We conclude that our laser system is well suited for isochoric heating of solid targets and an efficient transfer of the laser energy to the dense region of the target is possible. In cooperation with: T. Fischer, F. Brandl, G. Pretzler and O. Willi, Heinrich-Heine-University Duesseldorf, Germany, S. J. Rose, University of Oxford, United Kingdom [1] D. Riley et al., PRL 69, 3739 (1992). [2] A. Saemann et al., PRL 82, 4843 (1999). [3] S. J. Rose, J Phys B: Atom Molec Opt Phys, 25, 1667 (1992), 31, 2129 (1998).

The development of an efficient mass balance approach for the purity assignment of organic calibration standards.

PubMed

Davies, Stephen R; Alamgir, Mahiuddin; Chan, Benjamin K H; Dang, Thao; Jones, Kai; Krishnaswami, Maya; Luo, Yawen; Mitchell, Peter S R; Moawad, Michael; Swan, Hilton; Tarrant, Greg J

2015-10-01

The purity determination of organic calibration standards using the traditional mass balance approach is described. Demonstrated examples highlight the potential for bias in each measurement and the need to implement an approach that provides a cross-check for each result, affording fit for purpose purity values in a timely and cost-effective manner. Chromatographic techniques such as gas chromatography with flame ionisation detection (GC-FID) and high-performance liquid chromatography with UV detection (HPLC-UV), combined with mass and NMR spectroscopy, provide a detailed impurity profile allowing an efficient conversion of chromatographic peak areas into relative mass fractions, generally avoiding the need to calibrate each impurity present. For samples analysed by GC-FID, a conservative measurement uncertainty budget is described, including a component to cover potential variations in the response of each unidentified impurity. An alternative approach is also detailed in which extensive purification eliminates the detector response factor issue, facilitating the certification of a super-pure calibration standard which can be used to quantify the main component in less-pure candidate materials. This latter approach is particularly useful when applying HPLC analysis with UV detection. Key to the success of this approach is the application of both qualitative and quantitative (1)H NMR spectroscopy.

Alternative measures of lipophilicity: from octanol-water partitioning to IAM retention.

PubMed

Giaginis, Costas; Tsantili-Kakoulidou, Anna

2008-08-01

This review describes lipophilicity parameters currently used in drug design and QSAR studies. After a short historical overview, the complex nature of lipophilicity as the outcome of polar/nonpolar inter- and intramolecular interactions is analysed and considered as the background for the discussion of the different lipophilicity descriptors. The first part focuses on octanol-water partitioning of neutral and ionisable compounds, evaluates the efficiency of predictions and provides a short description of the experimental methods for the determination of distribution coefficients. A next part is dedicated to reversed-phase chromatographic techniques, HPLC and TLC in lipophilicity assessment. The two methods are evaluated for their efficiency to simulate octanol-water and the progress achieved in the refinement of suitable chromatographic conditions, in particular in the field of HPLC, is outlined. Liposomes as direct models of biological membranes are examined and phospolipophilicity is compared to the traditional lipophilicity concept. Difficulties associated with liposome-water partitioning are discussed. The last part focuses on Immobilised Artificial Membrane (IAM) chromatography as an alternative which combines membrane simulation with rapid measurements. IAM chromatographic retention is compared to octanol-water and liposome-water partitioning as well as to reversed-phase retention and its potential to predict biopartitioning and biological activities is discussed.

Inner-shell excitation and ionic fragmentation of molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hitchcock, A.P.; Tyliszczak, T.; Cavell, R.G.

1997-04-01

Inner-shell excitation and associated decay spectroscopies are site specific probes of electronic and geometrical structure and photoionization dynamics. X-ray absorption probes the geometric and electronic structure, while time-of-flight mass spectrometry with multi-coincidence detection provides information on the photofragmentation dynamics of the initially produced inner-shell state. Auger decay of inner-shell excited and ionised states is an efficient source of multiply charged ions. The charge separation and fragmentation of these species, studied by photoelectron-photoion-photoion coincidence (also called charge separation mass spectrometry) gives insights into bonding and electronic structure. In molecules, the dependence of the fragmentation process on the X-ray energy can revealmore » cases of site and/or state selective fragmentation. At the ALS the authors have examined the soft X-ray spectroscopy and ionic fragmentation of a number of molecules, including carboranes, silylenes, phosphorus halides, SF{sub 6} and CO{sub 2}. Their work is illustrated using results from the carborane and PF{sub 3} studies.« less

Prevalence and risk factors for carriage of multi-drug resistant Staphylococci in healthy cats and dogs

PubMed Central

Regula, Gertraud; Petrini, Orlando; Zinsstag, Jakob; Schelling, Esther

2013-01-01

We investigated the distribution of commensal staphylococcal species and determined the prevalence of multi-drug resistance in healthy cats and dogs. Risk factors associated with the carriage of multi-drug resistant strains were explored. Isolates from 256 dogs and 277 cats were identified at the species level using matrix-assisted laser desorption ionisation-time of flight mass spectrometry. The diversity of coagulase-negative Staphylococci (CNS) was high, with 22 species in dogs and 24 in cats. Multi-drug resistance was frequent (17%) and not always associated with the presence of the mecA gene. A stay in a veterinary clinic in the last year was associated with an increased risk of colonisation by multi-drug resistant Staphylococci (OR = 2.4, 95% CI: 1.1~5.2, p value LRT = 0.04). When identifying efficient control strategies against antibiotic resistance, the presence of mechanisms other than methicillin resistance and the possible role of CNS in the spread of resistance determinants should be considered. PMID:23820161

Determination of 105 antibiotic, anti-inflammatory, antiparasitic agents and tranquilizers by LC-MS/MS based on an acidic QuEChERS-like extraction.

PubMed

Desmarchelier, Aurélien; Fan, Kaïli; Minh Tien, Mai; Savoy, Marie-Claude; Tarres, Adrienne; Fuger, Denis; Goyon, Alexandre; Bessaire, Thomas; Mottier, Pascal

2018-04-01

A procedure for screening 105 veterinary drugs in foods by liquid chromatography tandem mass-spectrometry (LC-MS/MS) is presented. Its scope encompasses raw materials of animal origin (milk, meat, fish, egg and fat) but also related processed ingredients and finished products commonly used and manufactured by food business operators. Due to the complexity of the matrices considered and to efficiently deal with losses during extraction and matrix effects during MS source ionisation, each sample was analysed twice, that is 'unspiked' and 'spiked at the screening target concentration' using a QuEChERS-like extraction. The entire procedure was validated according to the European Community Reference Laboratories Residues Guidelines. False-negative and false-positive rates were below 5% for all veterinary drugs whatever the food matrix. Effectiveness of the procedure was further demonstrated through participation to five proficiency tests and its ruggedness demonstrated in quality control operations by a second laboratory.

A systematic review of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry compared to routine microbiological methods for the time taken to identify microbial organisms from positive blood cultures.

PubMed

Dixon, P; Davies, P; Hollingworth, W; Stoddart, M; MacGowan, A

2015-05-01

Bloodstream infections are a significant source of mortality and morbidity. Patient outcomes are improved by rapid identification of the causative pathogen and administration of appropriate antimicrobial therapy. Matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry has recently emerged as an alternative to microbiological identification. It is important to establish whether the costs of MALDI-TOF are justified by more timely identification and appropriate therapy, reduced length of stay and reduced hospital costs. We undertook a systematic review of the literature comparing MALDI-TOF and routine methods for the identification of the aetiological agent in patients with known or suspected bloodstream infection. The primary outcome of the review was the 'time to identify' organisms. Information on related measures such as 'time to appropriate antimicrobial treatment' and downstream hospital cost was also collected where reported. Ten of 775 articles identified met the inclusion criteria. All included studies were observational. MALDI-TOF identification was at least 24 h faster than routine methods in most circumstances. MADLI-TOF was associated with a reduction in downstream hospital costs and length of stay in studies reporting these outcomes. The observational studies reviewed provide evidence of potentially substantial time savings of MALDI-TOF in pathogen identification and instigation of appropriate therapy, which may also reduce hospital stay. Due to the small number of studies, all at relatively high risk of bias, this cannot be considered as definitive evidence of the impact of MALDI-TOF. More and better evidence, including impact on patient health and cost-effectiveness, is required.

Diagnostic performance of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry in blood bacterial infections: a systematic review and meta-analysis.

PubMed

Scott, Jamie S; Sterling, Sarah A; To, Harrison; Seals, Samantha R; Jones, Alan E

2016-07-01

Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) has shown promise in decreasing time to identification of causative organisms compared to traditional methods; however, the utility of MALDI-TOF MS in a heterogeneous clinical setting is uncertain. To perform a systematic review on the operational performance of the Bruker MALDI-TOF MS system and evaluate published cut-off values compared to traditional blood cultures. A comprehensive literature search was performed. Studies were included if they performed direct MALDI-TOF MS analysis of blood culture specimens in human patients with suspected bacterial infections using the Bruker Biotyper software. Sensitivities and specificities of the combined studies were estimated using a hierarchical random effects linear model (REML) incorporating cut-off scores of ≥1.7 and ≥2.0. Fifty publications were identified, with 11 studies included after final review. The estimated sensitivity utilising a cut-off of ≥2.0 from the combined studies was 74.6% (95% CI = 67.9-89.3%), with an estimated specificity of 88.0% (95% CI = 74.8-94.7%). When assessing a cut-off of ≥1.7, the combined sensitivity increases to 92.8% (95% CI = 87.4-96.0%), but the estimated specificity decreased to 81.2% (95% CI = 61.9-96.6%). In this analysis, MALDI-TOF MS showed acceptable sensitivity and specificity in bacterial speciation with the current recommended cut-off point compared to blood cultures; however, lowering the cut-off point from ≥2.0 to ≥1.7 would increase the sensitivity of the test without significant detrimental effect on the specificity, which could improve clinician confidence in their results.

Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope documentation for a series of zircon standards

USGS Publications Warehouse

Black, L.P.; Kamo, S.L.; Allen, C.M.; Davis, D.W.; Aleinikoff, J.N.; Valley, J.W.; Mundil, R.; Campbell, I.H.; Korsch, R.J.; Williams, I.S.; Foudoulis, C.

2004-01-01

Precise isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) documentation is given for two new Palaeozoic zircon standards (TEMORA 2 and R33). These data, in combination with results for previously documented standards (AS3, SL13, QGNG and TEMORA 1), provide the basis for a detailed investigation of inconsistencies in 206Pb/238U ages measured by microprobe. Although these ages are normally consistent between any two standards, their relative age offsets are often different from those established by ID-TIMS. This is true for both sensitive high-resolution ion-microprobe (SHRIMP) and excimer laser ablation-inductively coupled plasma-mass spectrometry (ELA-ICP-MS) dating, although the age offsets are in the opposite sense for the two techniques. Various factors have been investigated for possible correlations with age bias, in an attempt to resolve why the accuracy of the method is worse than the indicated precision. Crystallographic orientation, position on the grain-mount and oxygen isotopic composition are unrelated to the bias. There are, however, striking correlations between the 206Pb/238U age offsets and P, Sm and, most particularly, Nd abundances in the zircons. Although these are not believed to be the primary cause of this apparent matrix effect, they indicate that ionisation of 206Pb/238U is influenced, at least in part, by a combination of trace elements. Nd is sufficiently representative of the controlling trace elements that it provides a quantitative means of correcting for the microprobe age bias. This approach has the potential to reduce age biases associated with different techniques, different instrumentation and different standards within and between laboratories. Crown Copyright ?? 2004 Published by Elsevier B.V. All rights reserved.

Radioprotective potential of histamine on rat small intestine and uterus

PubMed Central

Carabajal, E.; Massari, N.; Croci, M.; Martinel Lamas, D.; Prestifilippo, J.P.; Ciraolo, P.; Bergoc, R.M.; Rivera, E.S.; Medina, V.A.

2012-01-01

The aim of this study was to improve knowledge about histamine radioprotective potential investigating its effect on reducing ionising radiation-induced injury and genotoxic damage on the rat small intestine and uterus. Forty 10-week-old male and 40 female Sprague-Dawley rats were divided into 4 groups. Histamine and histamine-5Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 24 h before irradiation. Histamine-5Gy and untreated-5Gy groups were irradiated with a dose of whole-body Cesium-137 irradiation. Three days after irradiation animals were sacrificed and tissues were removed, fixed, and stained with haematoxylin and eosin, and histological characteristics were evaluated. Proliferation, apoptosis and oxidative DNA markers were studied by immunohistochemistry, while micronucleus assay was performed to evaluate chromosomal damage. Histamine treatment reduced radiation-induced mucosal atrophy, oedema and vascular damage produced by ionising radiation, increasing the number of crypts per circumference (239±12 vs 160±10; P<0.01). This effect was associated with a reduction of radiation-induced intestinal crypts apoptosis. Additionally, histamine decreased the frequency of micronuclei formation and also significantly attenuated 8-OHdG immunoreactivity, a marker of DNA oxidative damage. Furthermore, radiation induced flattening of the endometrial surface, depletion of deep glands and reduced mitosis, effects that were completely blocked by histamine treatment. The expression of a proliferation marker in uterine luminal and glandular cells was markedly stimulated in histamine treated and irradiated rats. The obtained evidences indicate that histamine is a potential candidate as a safe radio-protective agent that might increase the therapeutic index of radiotherapy for intra-abdominal and pelvic cancers. However, its efficacy needs to be carefully investigated in prospective clinical trials. PMID:23361244

Rapid characterisation and identification of compounds in Saposhnikoviae Radix by high-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight mass spectrometry.

PubMed

Chen, Luxiao; Chen, Xiangyang; Su, Lei; Jiang, Yanyan; Liu, Bin

2018-04-01

Saposhnikoviae Radix (SR), the dried root of Saposhnikovia divaricata (Turcz.) Schischk. (Umbelliferae), is commonly used as a traditional Chinese medicine. In this study, a rapid and accurate method was firstly, developed for the qualitative analysis of SR by high-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-TOF-MS/MS). A total of 45 compounds were identified or tentatively characterised, including 13 chromones, 28 coumarins and four others. Among them, 16 compounds were identified from SR for the first time. In addition, six chromones reference standards, including two isolated compounds of 3'-O-angeloylhamaudol and norcimifugin from the extraction of SR, were used to study the fragmentation pathways of chromones. The developed method was effective for characterising the compounds of SR, and the results of the study enriched the understanding of the chemical connotation.

Application of thoron interference as a tool for simultaneous measurement of radon and thoron with a pulse ionisation chamber.

PubMed

Tripathi, R M; Sumesh, C G; Vinod Kumar, A; Puranik, V D

2013-07-01

Pulse ionisation chamber (PIC)-based monitors measuring radioactive gas radon ((222)Rn) without energy discrimination will have interference due to thoron ((220)Rn) present in the atmosphere. A technique has been developed to use this property of interference for simultaneous measurement of radon and thoron gas. These monitors work on the principle of counting of gross alphas emitted from radon and its progeny. A theoretical model has been developed for the variation of thoron sensitivity with respect to the flow rate of gas through the monitor. The thoron sensitivity of the monitor is found to vary with the flow rate of gas through the monitor. Using this sensitivity, the sampling procedure has been developed and verified for simultaneous measurement of radon and thoron. The PIC-measured radon and thoron concentration using this procedure agrees well with those measured by using standard radon and thoron discriminating monitor.

Analysis of dose-LET distribution in the human body irradiated by high energy hadrons.

PubMed

Sato, T; Tsuda, S; Sakamoto, Y; Yamaguchi, Y; Niita, K

2003-01-01

For the purposes of radiological protection, it is important to analyse profiles of the particle field inside a human body irradiated by high energy hadrons, since they can produce a variety of secondary particles which play an important role in the energy deposition process, and characterise their radiation qualities. Therefore Monte Carlo calculations were performed to evaluate dose distributions in terms of the linear energy transfer of ionising particles (dose-LET distribution) using a newly developed particle transport code (Particle and Heavy Ion Transport code System, PHITS) for incidences of neutrons, protons and pions with energies from 100 MeV to 200 GeV. Based on these calculations, it was found that more than 80% and 90% of the total deposition energies are attributed to ionisation by particles with LET below 10 keV microm(-1) for the irradiations of neutrons and the charged particles, respectively.

¹H, ¹³C, ¹⁵N HMBC, and ¹⁹F NMR spectroscopic characterisation of seized flephedrone, cut with benzocaine.

PubMed

Alotaibi, Majdah R; Husbands, Stephen M; Blagbrough, Ian S

2015-03-25

Flephedrone (4-fluoromethcathinone, 4-FMC) was analysed using (1)H, (13)C, (15)N HMBC, and (19)F observe spectroscopy, gas chromatography-flame ionisation detection (GC-FID), and electrospray ionisation-mass spectrometry (ESI-MS). Analysis of four 4-FMC samples (from a Bristol nightclub in 2013) showed that they all contained benzocaine as the cutting agent present in different amounts from 5 to 12%. Using these methods, we successfully differentiated between flephedrone regioisomers and mephedrone in an analytical method validated for flephedrone as a substituted cathinone. The data show that these now illegal cathinone-derived stimulants (highs) are now being cut; users cannot be certain of the purity of the drug they are taking. Furthermore, there are risks from the pharmaceutically active cutting agents themselves. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

The calibration of plane parallel ionisation chambers for the measurement of absorbed dose in electron beams of low to medium energies. Part 2: The PTW/MARKUS chamber.

PubMed

Cross, P; Freeman, N

1997-06-01

The purpose of Part 2 study of calibration methods for plane parallel ionisation chambers was to determine the feasibility of using beams of calibration of the MARKUS chamber other than the standard AAPM TG39 reference beams of 60Co and a high energy electron beam (E0 > or = 15 MeV). A previous study of the NACP chamber had demonstrated an acceptable level of accuracy with corresponding spread of -0.5% to +0.8% for its calibration in non-standard situations (medium to low energy electron and photon beams). For non-standard situations the spread in NDMARKUS values was found to be +/-2.5%. The results suggest that user calibrations of the MARKUS chamber in non-standard situations are associated with more uncertainties than is the case with the NACP chamber.

Electron ionisation induced fragmentation of ethyl 5(1H)-oxo- and 7(1H)-oxo-1-aryl-2,3-dihydroimidazo[1,2-a]-pyrimidine-6-carboxylates: evidence for an unusually regioselective rearrangement of M(+*) ions.

PubMed

Ovcharenko, V V; Pihlaja, K; Matosiuk, D

2001-01-01

The 70-eV electron ionisation (EI) mass spectra of the title compounds show clear differences between the 5-oxo and 7-oxo isomers due to regioselective fragmentations involving the ester function. Exceptionally abundant metastable peaks due to molecular ions fragmenting to [M -CO2](+.) were observed exclusively for the 7-oxo isomers, suggesting that the sufficiently long-lived molecular ions undergo a slow rearrangement preceding this fragmentation reaction. The results are contrasted to the available literature data on the ester group fragmentations involving the loss of CO2 and the EI mass spectrometry of pyrimidone beta-oxo esters. A reaction mechanism is proposed for the elimination of CO2 following ethyl group migration to the pyrimidone carbonyl oxygen. Copyright 2001 John Wiley & Sons, Ltd.

An evaluation of radiation damage to solid state components flown in low earth orbit satellites.

PubMed

Shin, Myung-Won; Kim, Myung-Hyun

2004-01-01

The effects of total ionising radiation dose upon commercial off-the-shelf semiconductors fitted to satellites operating in low Earth orbit (LEO) conditions was evaluated. The evaluation was performed for the Korea Institute of Technology SATellite-1, (KITSAT-1) which was equipped with commercial solid state components. Two approximate calculation models for space radiation shielding were developed. Verification was performed by comparing the results with detailed three-dimensional calculations using the Monte-Carlo method and measured data from KITSAT-1. It was confirmed that the developed approximate models were reliable for satellite shielding calculations. It was also found that commercial semiconductor devices, which were not radiation hardened, could be damaged within their lifetime due to the total ionising dose they are subject to in the LEO environment. To conclude, an intensive shielding analysis should be considered when commercial devices are used.

Identification of the isomers using principal component analysis (PCA) method

NASA Astrophysics Data System (ADS)

Kepceoǧlu, Abdullah; Gündoǧdu, Yasemin; Ledingham, Kenneth William David; Kilic, Hamdi Sukur

2016-03-01

In this work, we have carried out a detailed statistical analysis for experimental data of mass spectra from xylene isomers. Principle Component Analysis (PCA) was used to identify the isomers which cannot be distinguished using conventional statistical methods for interpretation of their mass spectra. Experiments have been carried out using a linear TOF-MS coupled to a femtosecond laser system as an energy source for the ionisation processes. We have performed experiments and collected data which has been analysed and interpreted using PCA as a multivariate analysis of these spectra. This demonstrates the strength of the method to get an insight for distinguishing the isomers which cannot be identified using conventional mass analysis obtained through dissociative ionisation processes on these molecules. The PCA results dependending on the laser pulse energy and the background pressure in the spectrometers have been presented in this work.

[Magnetic resonance enterography: technique and indications. Findings in Crohn's disease].

PubMed

Torregrosa, A; Pallardó, Y; Hinojosa, J; Insa, S; Molina, R

2013-09-01

Radiology with oral contrast, or enteroclysis, have traditionally been the techniques of choice in the examination of the small intestine, due to the excellent visualisation of the mucosal pattern. However, the absence of extra-luminal information and the use of ionising radiation have replaced these examinations with sectional techniques which enable the abdominal cavity to be viewed with good resolution. Magnetic resonance enterography is a simple technique, with no ionising radiation, provided quality images, distends the intestinal lumen well by the administration of non-reabsorbable oral substances, minimises peristalsis, and establishes a protocol which includes sequences with intravenous contrast. These properties can be used in patients with Crohn's disease, achieving good diagnostic precision in the assessment of activity and monitoring of treatment, in intestinal obstruction, in the suspicion of small intestine tumours, and in paediatric patients due to it being harmless. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

How fast can an AGN shut down? XMM-Newton observation of IC 2497

NASA Astrophysics Data System (ADS)

Schawinski, Kevin

2008-10-01

We propose to observe IC 2497 with XMM-Newton to detect, or rule out, an obscured AGN that might account for the illumination of `Hanny's Voorwerp'. The Voorwerp is a highly ionised cloud of gas extended over 15-25 kpc next to the spiral galaxy IC 2497. There is no source of ionisation within the Voorwerp, implicating a luminous 1E44 erg/s AGN in IC 2497 as the source. Swift XRT observations do not yield a detection, allowing the presence of a highly obscured, sufficiently luminous AGN. With 34 ksec of XMM observations, we could detect an obscured AGN down to 1E42 erg/s. We can thus either locate an obscured AGN, or we can for the first time constrain the shutdown time scale for a powerful AGN, as it drops by a factor of 100 in luminosity in 1E5 years.

Excitation of low-frequency residual currents at combination frequencies of an ionising two-colour laser pulse

NASA Astrophysics Data System (ADS)

Vvedenskii, N. V.; Kostin, V. A.; Laryushin, I. D.; Silaev, A. A.

2016-05-01

We have studied the processes of excitation of low-frequency residual currents in a plasma produced through ionisation of gases by two-colour laser pulses in laser-plasma schemes for THz generation. We have developed an analytical approach that allows one to find residual currents in the case when one of the components of a two-colour pulse is weak enough. The derived analytical expressions show that the effective generation of the residual current (and hence the effective THz generation) is possible if the ratio of the frequencies in the two-colour laser pulse is close to a rational fraction with a not very big odd sum of the numerator and denominator. The results of numerical calculations (including those based on the solution of the three-dimensional time-dependent Schrödinger equation) agree well with the analytical results.

End-to-end system test for solid-state microdosemeters.

PubMed

Pisacane, V L; Dolecek, Q E; Malak, H; Dicello, J F

2010-08-01

The gold standard in microdosemeters has been the tissue equivalent proportional counter (TEPC) that utilises a gas cavity. An alternative is the solid-state microdosemeter that replaces the gas with a condensed phase (silicon) detector with microscopic sensitive volumes. Calibrations of gas and solid-state microdosemeters are generally carried out using radiation sources built into the detector that impose restrictions on their handling, transportation and licensing in accordance with the regulations from international, national and local nuclear regulatory bodies. Here a novel method is presented for carrying out a calibration and end-to-end system test of a microdosemeter using low-energy photons as the initiating energy source, thus obviating the need for a regulated ionising radiation source. This technique may be utilised to calibrate both a solid-state microdosemeter and, with modification, a TEPC with the higher average ionisation energy of a gas.

Ellipticity-dependent of multiple ionisation methyl iodide cluster using 532 nm nanosecond laser

NASA Astrophysics Data System (ADS)

Tang, Bin; Zhao, Wuduo; Wang, Weiguo; Hua, Lei; Chen, Ping; Hou, Keyong; Huang, Yunguang; Li, Haiyang

2016-03-01

The dependence of multiply charged ions on laser ellipticity in methyl iodide clusters with 532 nm nanosecond laser was measured using a time-of-flight mass spectrometer. The intensities of multiply charged ions Iq+(q = 2-4) with circularly polarised laser pulse were clearly higher than those with linearly polarised laser pulse but the intensity of single charged ions I+ was inverse. And the dependences of ions on the optical polarisation state were investigated and a flower petal and square distribution for single charged ions (I+, C+) and multiply charged ions (I2+, I3+, I4+, C2+) were observed, respectively. A theoretical calculation was also proposed to simulate the distributions of ions and theoretical results fitted well with the experimental ones. It indicated that the high multiphoton ionisation probability in the initial stage would result in the disintegration of big clusters into small ones and suppress the production of multiply charged ions.

Brain Radiation Information Data Exchange (BRIDE): integration of experimental data from low-dose ionising radiation research for pathway discovery.

PubMed

Karapiperis, Christos; Kempf, Stefan J; Quintens, Roel; Azimzadeh, Omid; Vidal, Victoria Linares; Pazzaglia, Simonetta; Bazyka, Dimitry; Mastroberardino, Pier G; Scouras, Zacharias G; Tapio, Soile; Benotmane, Mohammed Abderrafi; Ouzounis, Christos A

2016-05-11

The underlying molecular processes representing stress responses to low-dose ionising radiation (LDIR) in mammals are just beginning to be understood. In particular, LDIR effects on the brain and their possible association with neurodegenerative disease are currently being explored using omics technologies. We describe a light-weight approach for the storage, analysis and distribution of relevant LDIR omics datasets. The data integration platform, called BRIDE, contains information from the literature as well as experimental information from transcriptomics and proteomics studies. It deploys a hybrid, distributed solution using both local storage and cloud technology. BRIDE can act as a knowledge broker for LDIR researchers, to facilitate molecular research on the systems biology of LDIR response in mammals. Its flexible design can capture a range of experimental information for genomics, epigenomics, transcriptomics, and proteomics. The data collection is available at: .

Single-particle energies and density of states in density functional theory

NASA Astrophysics Data System (ADS)

van Aggelen, H.; Chan, G. K.-L.

2015-07-01

Time-dependent density functional theory (TD-DFT) is commonly used as the foundation to obtain neutral excited states and transition weights in DFT, but does not allow direct access to density of states and single-particle energies, i.e. ionisation energies and electron affinities. Here we show that by extending TD-DFT to a superfluid formulation, which involves operators that break particle-number symmetry, we can obtain the density of states and single-particle energies from the poles of an appropriate superfluid response function. The standard Kohn- Sham eigenvalues emerge as the adiabatic limit of the superfluid response under the assumption that the exchange- correlation functional has no dependence on the superfluid density. The Kohn- Sham eigenvalues can thus be interpreted as approximations to the ionisation energies and electron affinities. Beyond this approximation, the formalism provides an incentive for creating a new class of density functionals specifically targeted at accurate single-particle eigenvalues and bandgaps.

Characteristics of Polarisation in the Ramsauer-Townsend Minima in Strongly Coupled Semiclassic Plasmas

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-10-01

The influence of quantum shielding on the Ramsauer-Townsend phenomena for the total electron-atom polarisation collision cross-section is investigated in partially ionised strongly coupled semiclassic plasmas. The result shows that the quantum shielding effect changes the position of the Ramsauer energy in partially ionised strongly coupled plasmas. It is also found that the quantum shielding effect enhances the total electron-atom collision cross-section when the collision energy is greater than the Ramsauer energy; however, it suppresses the collision cross-section when the collision energy is smaller than the Ramsauer energy. In addition, it is shown that the plasma screening effect significantly changes the position of the Ramsauer energy and the influence of plasma screening on the magnitude of the collision cross-section is more significant near the Ramsauer energy domain. The variations of the Ramsauer energy and the collision cross-section due to the quantum shielding effect are also discussed.

Influence of inelastic collisions with hydrogen atoms on the non-LTE modelling of Ca I and Ca II lines in late-type stars

NASA Astrophysics Data System (ADS)

Mashonkina, L.; Sitnova, T.; Belyaev, A. K.

2017-09-01

We performed the non-local thermodynamic equilibrium (non-LTE, NLTE) calculations for Ca I-II with the updated model atom that includes new quantum-mechanical rate coefficients for Ca I + H I collisions from two recent studies and investigated the accuracy of calcium abundance determinations using the Sun, Procyon, and five metal-poor (MP, -2.6 ≤ [Fe/H] ≤-1.3) stars with well-determined stellar parameters. Including H I collisions substantially reduces over-ionisation of Ca I in the line formation layers compared with the case of pure electronic collisions and thus the NLTE effects on abundances derived from Ca I lines. We show that both collisional recipes lead to very similar NLTE results. As for Ca II, the classical Drawinian rates scaled by SH = 0.1 are still applied. When using the subordinate lines of Ca I and the high-excitation lines of Ca II, NLTE provides the smaller line-to-line scatter compared with the LTE case for each star. For Procyon, NLTE removes a steep trend with line strength among strong Ca I lines seen in LTE and leads to consistent [Ca/H] abundances from the two ionisation stages. In the MP stars, the NLTE abundance from Ca II 8498 Å agrees well with the abundance from the Ca I subordinate lines, in contrast to LTE, where the abundance difference grows towards lower metallicity and reaches 0.46 dex in BD -13°3442 ([Fe/H] = -2.62). NLTE largely removes abundance discrepancies between the high-excitation lines of Ca II and Ca II 8498 Å obtained for our four [Fe/H] < -2 stars under the LTE assumption. We investigated the formation of the Ca I resonance line in the [Fe/H] < -2 stars. When the calcium abundance varies between [Ca/H] ≃ -1.8 and -2.3, photon loss in the resonance line itself in the uppermost atmospheric layers drives the strengthening of the line core compared with the LTE case, and this effect prevails over the weakening of the line wings, resulting in negative NLTE abundance correction and underestimation of the abundance derived from Ca I 4226 Å compared with that from the subordinate lines, by 0.08 to 0.32 dex. This problem may be related to the use of classical homogeneous (1D) model atmospheres. The situation is improved when the calcium abundance decreases and the Ca I 4226 Å line formation depths are shifted into deep atmospheric layers that are dominated by over-ionisation of Ca I. However, the departures from LTE are still underestimated for Ca I 4226 Å at [Ca/H] ≃ -4.4 (HE 0557-4840). Consistent NLTE abundances from the Ca I resonance line and the Ca II lines are found for HE 0107-5240 and HE 1327-2326 with [Ca/H] ≤-5. Thus, the Ca I/Ca II ionisation equilibrium method can successfully be applied to determine surface gravities of [Ca/H] ≾ -5 stars. We provide the NLTE abundance corrections for 28 lines of Ca I in a grid of model atmospheres with 5000 K ≤ Teff ≤ 6500 K, 2.5 ≤ log g ≤ 4.5, -4 ≤ [Fe/H] ≤ 0, which is suitable for abundance analysis of FGK-type dwarfs and subgiants.

Estimation of the peak entrance surface air kerma for patients undergoing computed tomography-guided procedures.

PubMed

Avilés Lucas, P; Dance, D R; Castellano, I A; Vañó, E

2005-01-01

The purpose of this work was to develop a method for estimating the patient peak entrance surface air kerma from measurements using a pencil ionisation chamber on dosimetry phantoms exposed in a computed tomography (CT) scanner. The method described is especially relevant for CT fluoroscopy and CT perfusion procedures where the peak entrance surface air kerma is the risk-related quantity of primary concern. Pencil ionisation chamber measurements include scattered radiation, which is outside the primary radiation field, and that must be subtracted in order to derive the peak entrance surface air kerma. A Monte Carlo computer model has therefore been used to calculate correction factors, which may be applied to measurements of the CT dose index obtained using a pencil ionisation chamber in order to estimate the peak entrance surface air kerma. The calculations were made for beam widths of 5, 7, 10 and 20 mm, for seven positions of the phantom, and for the geometry of a GE HiSpeed CT/i scanner. The program was validated by comparing measurements and calculations of CTDI for various vertical positions of the phantom and by directly estimating the peak ESAK using the program. Both validations showed agreement within statistical uncertainties (standard deviation of 2.3% or less). For the GE machine, the correction factors vary by approximately 10% with slice width for a fixed phantom position, being largest for the 20 mm beam width, and at that beam width range from 0.87 when the phantom surface is at the isocentre to 1.23 when it is displaced vertically by 24 cm.

Teaching about Radioactivity and Ionising Radiation: An Alternative Approach.

ERIC Educational Resources Information Center

Millar, Robin; And Others

1990-01-01

Children's ideas about radiation and radioactivity are reviewed and several common areas of misunderstanding are identified. An approach to teaching the topic at the secondary school level which seeks to specifically address known difficulties is outlined. (CW)

Ionisation of atomic hydrogen by positron impact

NASA Technical Reports Server (NTRS)

Spicher, Gottfried; Olsson, Bjorn; Raith, Wilhelm; Sinapius, Guenther; Sperber, Wolfgang

1990-01-01

With the crossed beam apparatus the relative impact-ionization cross section of atomic hydrogen by positron impact was measured. A layout of the scattering region is given. The first measurements on the ionization of atomic hydrogen by positron impact are also given.

Prophylactic intravenous calcium therapy for exchange blood transfusion in the newborn.

PubMed

Ogunlesi, Tinuade A; Lesi, Foluso Ea; Oduwole, Olabisi

2017-10-12

Exchange blood transfusion (EBT) is a form of whole blood transfusion in which the total blood volume is replaced within a few hours. In perinatal and neonatal medicine, EBT is most often used in the management of severe anaemia or severe hyperbilirubinaemia in the first week of life. Hypocalcaemia, one of the common morbidities associated with EBT, is thought to arise from the chelating effects of the citrate commonly used as an anticoagulant in the donor's blood. This disorder manifests with muscular and nervous irritability and cardiac arrhythmias. To determine whether the use of prophylactic calcium reduces the risk of hypocalcaemia-related morbidities and death among newborn infants receiving EBT. We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 5), MEDLINE via PubMed (1966 to 29 June 2016), Embase (1980 to 29 June 2016), and CINAHL (1982 to 29 June 2016). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. All randomised and quasi-randomised trials of prophylactic intravenous calcium in EBT for newborns. Two review authors independently assessed and extracted data on methods, participants, interventions, and outcomes (mean total and ionised serum calcium before and after EBT and the presence of adverse events such as hypoglycaemia, apnoea, cardiac arrest, and death immediately after EBT). We reported results as means difference (MD) with 95% confidence intervals (CI) for continuous outcomes and risk ratio (RR) and risk differences (RD) and 95% CIs for dichotomous outcomes. We assessed quality using the Cochrane 'Risk of bias' assessment tool and the GRADE system. We found only one quasi-randomised trial with 30 participants that met our inclusion criteria. In the small trial, total and ionised serum calcium levels were measured immediately before and immediately after EBT. All the participants were included in the final analysis and all the important outcomes were reported. Primary outcomesThere was one death in each group (RR 1.00, 95% CI 0.07 to 14.55; RD 0.00, 95% CI -0.18 to 0.18; participants = 30; studies = 1). The study did not report the presence of cardiac arrhythmias within one week of EBT and the number of infants with serum calcium levels (total less than 8 mg/dL (2 mmol/L) or ionised less than 4.4 mg/dL (1.1 mmol/L)).Pair-wise comparison of EBT with intravenous 10% calcium gluconate versus EBT without intravenous calcium (change from baseline) showed mean total serum calcium was raised in the intervention group compared to the control group (MD -0.46, 95% CI -0.81 to -0.11; participants = 30; studies = 1). Very low-quality evidence also indicated an increase in the levels of mean ionised serum calcium in the intervention group compared to the control group (MD -0.22, 95% CI -0.33 to -0.11; participants = 30; studies = 1). Secondary outcomesAdverse reactions to intravenous calcium therapy included cardiac arrest in one neonate in the intervention arm (RR 3.00, 95% CI 0.13 to 68.26; RD 0.07, 95% CI -0.10 to 0.23; participants = 30; studies = 1). There was apnoea and hypoglycaemia (RR 1.00, 95% CI 0.07 to 14.55; RD 0.00, 95% CI -0.18 to 0.18; participants = 30; studies = 1) in the two neonates who died. Data were not available for other major secondary outcomes such as the number of infants with reduced serum magnesium, reduced parathormone, increased calcitonin, presence of seizures, carpopedal spasm, jitteriness and prolonged QTc interval on electrocardiography within one week of EBT. Very low-quality data from one quasi-randomised controlled trial suggested that the mean serum total and ionised calcium increased in the study group but decreased in the control group immediately after EBT. However, the mean values of total and ionised calcium in both arms of studies remained within international reference ranges. Unfortunately, data were not available to assess the trend of total and ionised serum calcium to the end of the first week after EBT. Therefore, due to the very low quality of evidence available, it is difficult to support or reject the continual use of prophylactic intravenous calcium in newborn infants receiving EBT. Researchers are encouraged to conduct more robustly designed trials with larger numbers of participants, and particularly, addressing the pattern of differences based on gestational age of participants, type of anticoagulant used, and the volume of blood used.

Analytical strategy for the determination of non-steroidal anti-inflammatory drugs in plasma and improved analytical strategy for the determination of authorized and non-authorized non-steroidal anti-inflammatory drugs in milk by LC-MS/MS.

PubMed

Dowling, Geraldine; Malone, Edward; Harbison, Tom; Martin, Sheila

2010-07-01

A sensitive and selective method for the determination of six non-steroidal anti-inflammatory drugs (NSAIDs) in bovine plasma was developed. An improved method for the determination of authorized and non-authorized residues of 10 non-steroidal anti-inflammatory drugs in milk was developed. Analytes were separated and acquired by high performance liquid chromatography coupled with an electrospray ionisation tandem mass spectrometer (ESI-MS/MS). Target compounds were acidified in plasma, and plasma and milk samples were extracted with acetonitrile and both extracts were purified on an improved solid phase extraction procedure utilising Evolute ABN cartridges. The accuracy of the methods for milk and plasma was between 73 and 109%. The precision of the method for authorized and non-authorized NSAIDs in milk and plasma expressed as % RSD, for the within lab reproducibility was less than 16%. The % RSD for authorized NSAIDs at their associated MRL(s) in milk was less than 10% for meloxicam, flunixin and tolfenamic acid and was less than 25% for hydroxy flunixin. The methods were validated according to Commission Decision 2002/657/EC.

Daytime dependence of disturbances of ionospheric Es-layers connected to earthquakes

NASA Astrophysics Data System (ADS)

Liperovskaya, E. V.; Liperovsky, A. V.; Meister, C.-V.; Silina, A. S.

2012-04-01

In the present work variations of the semi-transparency of the sporadic E-layer of the ionosphere due to seismic activities are studied. The semi-transparency Q is determined by the blanketing frequency fbEs and the characteristic frequency foEs, Q = (foEs - fbEs)/fbEs. At low values of the blanketing frequency fbEs, the critical frequency foEs does not describe the maximum ionisation density of the Es-layer, as the critical frequencies of regular ionospheric layers (e.g. foF2) do, but it describes the occurrence of small-scall (tenths of meters) inhomogeneities of the ionisation density along the vertical in the layer. The maximum ionisation density of the sporadic layer is proportional to the square of fbEs. In the case of vertical ionospheric sounding, the sporadic layer becomes transparent for signals with frequencies larger than fbEs. Investigations showed that about three days before an earthquake an increase of the semi-transparency interval is observed during sunset and sunrise. In the present work, analogous results are found for data of the vertical sounding stations "Tokyo" and "Petropavlovsk-Kamchatsky". Using the method of superposition of epoches, more than 50 earthquakes with magnitudes M > 5, depths h < 40 km, and distances between the station and the epicenter R < 300 km are considered in case of the vertical sounding station "Tokyo". More than 20 earthquakes with such parameters were analysed in case of the station "Petropavlovsk-Kamchatsky". Days with strong geomagnetic activity were excluded from the analysis. According to the station "Petropavlovsk-Kamchatsky" about 1-3 days before earthquakes, an increase of Es-spread is observed a few hours before midnight. This increase is a sign of large-scale inhomogeneities in the sporadic layers.

Laboratory spectroscopy and astronomical significance of the fully-benzenoid PAH triphenylene and its cation

NASA Astrophysics Data System (ADS)

Kofman, V.; Sarre, P. J.; Hibbins, R. E.; ten Kate, I. L.; Linnartz, H.

2017-06-01

Triphenylene (C18H12) is a highly symmetric polycyclic aromatic hydrocarbon (PAH) molecule with a 'fully-benzenoid' electronic structure. This confers a high chemical stability compared with PAHs of similar size. Although numerous infrared and UV-vis experimental spectroscopic and theoretical studies of a wide range PAHs in an astrophysical context have been conducted, triphenylene and its radical cation have received almost no attention. There exists a huge body of spectroscopic evidence for neutral and ionised PAHs in astrophysical sources, obtained principally through detection of infrared emission features that are characteristic of PAHs as a chemical class. However, it has so far not proved possible to identify spectroscopically a single isolated PAH in space, although PAHs including triphenylene have been detected mass spectrometrically in meteorites. In this work we focus on recording laboratory electronic spectra of neutral and ionised triphenylene between 220 and 780 nm, trapped in H2O ice and solid argon at 12 K. The studies are motivated by the potential for spectroscopic astronomical detection of electronic absorption spectra of PAHs in ice mantles on interstellar grains as discussed by Linnartz (2014), and were performed also in a cold Ar matrix to provide guidance as to whether triphenylene (particularly in its singly positively ionised form) could be a viable candidate for any of the unidentified diffuse interstellar absorption bands. Based on the argon-matrix experimental results, comparison is made with previously unpublished astronomical spectra near 400 nm which contain broad interstellar absorption features consistent with the predictions from the laboratory matrix spectra, thus providing motivation for the recording of gas-phase electronic spectra of the internally cold triphenylene cation.

Quantitative determination of sulfisoxazole and its three N-acetylated metabolites using HPLC-MS/MS, and the saturable pharmacokinetics of sulfisoxazole in mice.

PubMed

Oh, Kyungsoo; Baek, Moon-Chang; Kang, Wonku

2016-09-10

Sulfisoxazole (SFX) is still used in combination with trimethoprim in cattle despite adverse drug reactions (e.g., urolithiasis). Recently, SFX is known to be a promising repositioned drug candidate for pulmonary hypertension and cancer. We developed a simultaneous determination method of SFX and its N-acetylated metabolites (N(1)-acetyl SFX, N1AS; N(4)-acetyl SFX, N4AS; diacetyl SFX, DAS) using HPLC-MS/MS for the first time, and examined the pharmacokinetics of SFX in mice. N1AS and DAS were converted rapidly to SFX and N4AS, respectively, in mouse plasma. The time courses of plasma SFX and N4AS concentrations were well-characterised following the oral administration of SFX to mice. The absorption, metabolism, and/or excretion of SFX given at >700mg/kg may be saturable, and in contrast to humans and rats, the extent of systemic exposure of mice to N4AS was much greater than that of SFX. Interestingly, the acetyl groups at both N1- and N4-positions were degraded during the ionisation required to generate precursor ions. In additional experiments the carboxyl group of N-acetyl-5-aminosalicylic acid (NA5AS) was lost instead of the acetyl group during the ionisation, and acetaminophen (AAP) appeared. As the acetyl and carboxyl groups of some substances can be degraded during ionisation in the mass spectrometer, caution is appropriate when it is sought to simultaneously quantify similar structures containing these moieties; chromatographic separation is essential. Copyright © 2016 Elsevier B.V. All rights reserved.

Concentration-dependent effect of hypocalcaemia on mortality of patients with critical bleeding requiring massive transfusion: a cohort study.

PubMed

Ho, K M; Leonard, A D

2011-01-01

Mortality of patients with critical bleeding requiring massive transfusion is high. Although hypothermia, acidosis and coagulopathy have been well described as important determinants of mortality in patients with critical bleeding requiring massive transfusion, the risk factors and outcome associated with hypocalcaemia in these patients remain uncertain. This cohort study assessed the relationship between the lowest ionised calcium concentration during the 24-hour period of critical bleeding and the hospital mortality of 352 consecutive patients, while adjusting for diagnosis, acidosis, coagulation results, transfusion requirements and use of recombinant factor VIIa. Hypocalcaemia was common (mean concentrations 0.77 mmol/l, SD 0.19) and had a linear; concentration-dependent relationship with mortality (odds ratio [OR] 1.25 per 0.1 mmol/l decrement, 95% confidence interval [CI]: 1.04 to 1.52; P = 0.02). Hypocalcaemia accounted for 12.5% of the variability and was more important than the lowest fibrinogen concentrations (10.8%), acidosis (7.9%) and lowest platelet counts (7.7%) in predicting hospital mortality. The amount of fresh frozen plasma transfused (OR 1.09 per unit, 95% CI: 1.02 to 1.17; P = 0.02) and acidosis (OR 1.45 per 0.1 decrement, 95% CI: 1.19 to 1.72; P = 0.01) were associated with the occurrence of severe hypocalcaemia (< 0.8 mmol/l). In conclusion, ionised calcium concentrations had an inverse concentration-dependent relationship with mortality of patients with critical bleeding requiring massive transfusion. Both acidosis and the amount of fresh frozen plasma transfused were the main risk factors for severe hypocalcaemia. Further research is needed to determine whether preventing ionised hypocalcaemia can reduce mortality of patients with critical bleeding requiring massive transfusion.

N-deethylation and N-oxidation of etamiphylline: identification of etamiphylline-N-oxide in greyhound urine by high performance liquid chromatography-mass spectrometry.

PubMed

Dumasia, M C; Teale, P

2005-01-04

Millophyline-V, (etamiphylline camsylate) was administered intramuscularly to two racing greyhounds at a dose of 10 mg kg(-1). Unhydrolysed pre- and post-administration urine samples were extracted using mixed mode solid phase extraction (SPE) cartridges, the basic isolates derivatised as trimethylsilyl ethers and analysed by positive ion electron ionisation gas chromatography-mass spectrometry (GC/EI+/MS). The parent drug and one metabolite, N-desethyletamiphylline, were detected in urine for up to 72 h. For semi-quantification, urine samples were extracted on-line using a Prospekt sample handler. The analytes retained on the C2 SPE cartridge were eluted by the mobile phase directly on to the analytical high performance liquid chromatography column and analysed by positive ion atmospheric pressure chemical ionisation (LC/APCI+) MS in the multiple selective-ion recording mode. A major peak containing both ions (m/z) 280 and (m/z) 252 was observed. Full scan LC/APCI+/MS of the unknown indicated that the ion at (m/z) 280 was formed by the loss of an oxygen atom [MH+ -->(MH+-O)]. Samples were analysed by positive ion electrospray ionisation LC/MS on two different instruments and the unknown compound was identified as an N-oxide of the tert. nitrogen atom of the 2-(diethylamino)ethyl substituent on N7 of the theophylline nucleus. This compound has not been reported previously either as an in vivo or in vitro metabolite of etamiphylline in any species. Thermal decomposition of the N-oxide could lead to an increase the detection period of the parent drug during routine GC/MS screening of post-competition greyhound urine samples.

Negative-ion atmospheric pressure ionisation of semi-volatile fluorinated compounds for ultra-high-performance liquid chromatography tandem mass spectrometry analysis.

PubMed

Ayala-Cabrera, Juan F; Javier Santos, F; Moyano, Encarnación

2018-05-24

In this work, the feasibility of negative-ion atmospheric pressure chemical ionisation (APCI) and atmospheric pressure photoionisation (APPI) for ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) determination of fluorotelomer alcohols (FTOHs), fluorinated octanesulfonamides (FOSAs) and fluorinated octanesulfonamido-ethanols (FOSEs) was evaluated. The study of the effect of mobile phase composition on the atmospheric pressure ionisation of these compounds indicated that methanol/water mixtures provided the best responses in APCI, while acetonitrile/water with a post-column addition of toluene as dopant was the most appropriated mixture in APPI. Under the optimal working conditions, most of the target compounds produced the ion [M-H] - as base peak, although in-source collision-induced dissociation fragment ions in APCI and APPI and superoxide adduct ions [M+O 2 ] -• in APPI were also present. These ions proved to be more useful as precursor ions for MS/MS determination than the adduct ions generated in electrospray. Although the UHPLC-APCI-MS/MS method allowed the determination of these semi-volatile compounds at low concentration levels, the analysis by UHPLC-APPI-MS/MS provided the lowest limits of detection and it was applied to the analysis of water samples in combination with solid-phase extraction. Quality parameters demonstrated the good performance of the proposed method, providing low method limits of detection (0.3-6 ng L -1 ), good precision (RSD % < 5%) and an accurate quantification (relative error % < 14%). Among the river water samples analysed by the developed method, 4:2 FTOH and N-EtFOSA were determined at 30 and 780 ng L -1 , respectively.

Identification of substances migrating from plastic baby bottles using a combination of low-resolution and high-resolution mass spectrometric analysers coupled to gas and liquid chromatography.

PubMed

Onghena, Matthias; Van Hoeck, Els; Van Loco, Joris; Ibáñez, María; Cherta, Laura; Portolés, Tania; Pitarch, Elena; Hernandéz, Félix; Lemière, Filip; Covaci, Adrian

2015-11-01

This work presents a strategy for elucidation of unknown migrants from plastic food contact materials (baby bottles) using a combination of analytical techniques in an untargeted approach. First, gas chromatography (GC) coupled to mass spectrometry (MS) in electron ionisation mode was used to identify migrants through spectral library matching. When no acceptable match was obtained, a second analysis by GC-(electron ionisation) high resolution mass spectrometry time of flight (TOF) was applied to obtain accurate mass fragmentation spectra and isotopic patterns. Databases were then searched to find a possible elemental composition for the unknown compounds. Finally, a GC hybrid quadrupole-TOF-MS with an atmospheric pressure chemical ionisation source was used to obtain the molecular ion or the protonated molecule. Accurate mass data also provided additional information on the fragmentation behaviour as two acquisition functions with different collision energies were available (MS(E) approach). In the low-energy function, limited fragmentation took place, whereas for the high-energy function, fragmentation was enhanced. For less volatile unknowns, ultra-high pressure liquid chromatography-quadrupole-TOF-MS was additionally applied. Using a home-made database containing common migrating compounds and plastic additives, tentative identification was made for several positive findings based on accurate mass of the (de)protonated molecule, product ion fragments and characteristic isotopic ions. Six illustrative examples are shown to demonstrate the modus operandi and the difficulties encountered during identification. The combination of these techniques was proven to be a powerful tool for the elucidation of unknown migrating compounds from plastic baby bottles. Copyright © 2015 John Wiley & Sons, Ltd.

Increased frequency of chromosome translocations in airline pilots with long-term flying experience

PubMed Central

Yong, L C; Sigurdson, A J; Ward, E M; Waters, M A; Whelan, E A; Petersen, M R; Bhatti, P; Ramsey, M J; Ron, E; Tucker, J D

2008-01-01

Background Chromosome translocations are an established biomarker of cumulative exposure to external ionising radiation. Airline pilots are exposed to cosmic ionising radiation, but few flight crew studies have examined translocations in relation to flight experience. Methods We determined the frequency of translocations in the peripheral blood lymphocytes of 83 airline pilots and 50 comparison subjects (mean age 47 and 46 years, respectively). Translocations were scored in an average of 1039 cell equivalents (CE) per subject using fluorescence in situ hybridisation (FISH) whole chromo-some painting and expressed per 100 CE. Negative binomial regression models were used to assess the relationship between translocation frequency and exposure status and flight years, adjusting for age, diagnostic x ray procedures, and military flying. Results There was no significant difference in the adjusted mean translocation frequency of pilots and comparison subjects (0.37 (SE 0.04) vs 0.38 (SE 0.06) translocations/100 CE, respectively). However, among pilots, the adjusted translocation frequency was significantly associated with flight years (p = 0.01) with rate ratios of 1.06 (95% CI 1.01 to 1.11) and 1.81 (95% CI 1.16 to 2.82) for a 1- and 10-year incremental increase in flight years, respectively. The adjusted rate ratio for pilots in the highest compared to the lowest quartile of flight years was 2.59 (95% CI 1.26 to 5.33). Conclusions This data suggests that pilots with long-term flying experience may be exposed to biologically significant doses of ionising radiation. Epidemiological studies with longer follow-up of larger cohorts of pilots with a wide range of radiation exposure levels are needed to clarify the relationship between cosmic radiation exposure and cancer risk. PMID:19074211

Analytical mass spectrometry of poly(ethylene glycol) additives in artists' acrylic emulsion media, artists' paints, and microsamples from acrylic paintings using MALDI-MS and nanospray-ESI-MS

NASA Astrophysics Data System (ADS)

Hoogland, F. G.; Boon, J. J.

2009-07-01

Poly(ethylene glycol) (PEG) compounds in artists' acrylic emulsion paint products from different paint manufacturers, ranging from base emulsions (Rohm and Haas, Röhm and Scott Bader), to modified emulsions and complete paints (Rowney, Winsor and Newton, Golden, Liquitex, Lascaux), were characterised with a newly developed mass spectrometric method which combines data from Matrix assisted laser desorption/ionisation mass spectrometry (MALDI-MS) and nano-electrospray ionisation mass spectrometry (nano-ESI-MS(MS)). MALDI-MS was used for the determination of the molar mass distribution (MMD) and calculation of the molar mass averages (Mw and Mn), the polydispersity index (D) and the relative amount of a specific distribution if multiple PEGs were present. Electrospray ionisation mass spectrometry was used for the end-group analysis. Three different classes of polymers was found being PEG, polypropylene glycol (PPG) and a block copolymer of polyethylene glycol/polypropylene glycol (PEG/PPG) with molar mass averages ranging from 400 to 4200 Da. PEG compounds with a nonylphenyl or an octylphenyl hydrophobic end-group are most common. The hydrophilic end-groups observed are hydroxide and/or sulphate. Water extracts of microsamples from a palette by David Hockney dating from 1970 and samples paintings by Patrick Caulfield (1936-2005) and John Hoyland (born in 1934) were investigated with the same technique. Although some artist paint manufacturers use the same specific base emulsions to make their paints, the composition of the PEG compounds present in the water extracts of the palette and paintings samples made it possible, in some cases, to suggest a specific brand of paint used by the artist.

Increased frequency of chromosome translocations in airline pilots with long-term flying experience.

PubMed

Yong, L C; Sigurdson, A J; Ward, E M; Waters, M A; Whelan, E A; Petersen, M R; Bhatti, P; Ramsey, M J; Ron, E; Tucker, J D

2009-01-01

Chromosome translocations are an established biomarker of cumulative exposure to external ionising radiation. Airline pilots are exposed to cosmic ionising radiation, but few flight crew studies have examined translocations in relation to flight experience. We determined the frequency of translocations in the peripheral blood lymphocytes of 83 airline pilots and 50 comparison subjects (mean age 47 and 46 years, respectively). Translocations were scored in an average of 1039 cell equivalents (CE) per subject using fluorescence in situ hybridisation (FISH) whole chromosome painting and expressed per 100 CE. Negative binomial regression models were used to assess the relationship between translocation frequency and exposure status and flight years, adjusting for age, diagnostic x ray procedures, and military flying. There was no significant difference in the adjusted mean translocation frequency of pilots and comparison subjects (0.37 (SE 0.04) vs 0.38 (SE 0.06) translocations/100 CE, respectively). However, among pilots, the adjusted translocation frequency was significantly associated with flight years (p = 0.01) with rate ratios of 1.06 (95% CI 1.01 to 1.11) and 1.81 (95% CI 1.16 to 2.82) for a 1- and 10-year incremental increase in flight years, respectively. The adjusted rate ratio for pilots in the highest compared to the lowest quartile of flight years was 2.59 (95% CI 1.26 to 5.33). Our data suggests that pilots with long-term flying experience may be exposed to biologically significant doses of ionising radiation. Epidemiological studies with longer follow-up of larger cohorts of pilots with a wide range of radiation exposure levels are needed to clarify the relationship between cosmic radiation exposure and cancer risk.

Study of point- and cluster-defects in radiation-damaged silicon

NASA Astrophysics Data System (ADS)

Donegani, Elena M.; Fretwurst, Eckhart; Garutti, Erika; Klanner, Robert; Lindstroem, Gunnar; Pintilie, Ioana; Radu, Roxana; Schwandt, Joern

2018-08-01

Non-ionising energy loss of radiation produces point defects and defect clusters in silicon, which result in a significant degradation of sensor performance. In this contribution results from TSC (Thermally Stimulated Current) defect spectroscopy for silicon pad diodes irradiated by electrons to fluences of a few 1014 cm-2 and energies between 3.5 and 27 MeV for isochronal annealing between 80 and 280∘C, are presented. A method based on SRH (Shockley-Read-Hall) statistics is introduced, which assumes that the ionisation energy of the defects in a cluster depends on the fraction of occupied traps. The difference of ionisation energy of an isolated point defect and a fully occupied cluster, ΔEa, is extracted from the TSC data. For the VOi (vacancy-oxygen interstitial) defect ΔEa = 0 is found, which confirms that it is a point defect, and validates the method for point defects. For clusters made of deep acceptors the ΔEa values for different defects are determined after annealing at 80∘C as a function of electron energy, and for the irradiation with 15 MeV electrons as a function of annealing temperature. For the irradiation with 3.5 MeV electrons the value ΔEa = 0 is found, whereas for the electron energies of 6-27 MeV ΔEa > 0. This agrees with the expected threshold of about 5 MeV for cluster formation by electrons. The ΔEa values determined as a function of annealing temperature show that the annealing rate is different for different defects. A naive diffusion model is used to estimate the temperature dependencies of the diffusion of the defects in the clusters.

An X-ray/SDSS sample. II. AGN-driven outflowing gas plasma properties

NASA Astrophysics Data System (ADS)

Perna, M.; Lanzuisi, G.; Brusa, M.; Cresci, G.; Mignoli, M.

2017-10-01

Aims: Galaxy-scale outflows are currently observed in many active galactic nuclei (AGNs); however, characterisation of them in terms of their (multi-) phase nature, amount of flowing material, and effects on their host galaxy is still unresolved. In particular, ionised gas mass outflow rate and related energetics are still affected by many sources of uncertainty. In this respect, outflowing gas plasma conditions, being largely unknown, play a crucial role. Methods: We have analysed stacked spectra and sub-samples of sources with high signal-to-noise temperature- and density-sensitive emission lines to derive the plasma properties of the outflowing ionised gas component. We did this by taking advantage of the spectroscopic analysis results we obtained while studying the X-ray/SDSS sample of 563 AGNs at z < 0.8 presented in our companion paper. For these sources, we also studied in detail various diagnostic diagrams to infer information about outflowing gas ionisation mechanisms. Results: We derive, for the first time, median values for electron temperature and density of outflowing gas from medium-size samples ( 30 targets) and stacked spectra of AGNs. Evidence of shock excitation are found for outflowing gas. Conclusions: We measure electron temperatures of the order of 1.7 × 104 K and densities of 1200 cm-3 for faint and moderately luminous AGNs (intrinsic X-ray luminosity 40.5 < log (LX) < 44 in the 2-10 keV band). We note that the electron density that is usually assumed (Ne = 100 cm-3) in ejected material might result in relevant overestimates of flow mass rates and energetics and, as a consequence, of the effects of AGN-driven outflows on the host galaxy.

A sensitive multi-residue method for the determination of 35 micropollutants including pharmaceuticals, iodinated contrast media and pesticides in water.

PubMed

Valls-Cantenys, Carme; Scheurer, Marco; Iglesias, Mònica; Sacher, Frank; Brauch, Heinz-Jürgen; Salvadó, Victoria

2016-09-01

A sensitive, multi-residue method using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to determine a representative group of 35 analytes, including corrosion inhibitors, pesticides and pharmaceuticals such as analgesic and anti-inflammatory drugs, five iodinated contrast media, β-blockers and some of their metabolites and transformation products in water samples. Few other methods are capable of determining such a broad range of contrast media together with other analytes. We studied the parameters affecting the extraction of the target analytes, including sorbent selection and extraction conditions, their chromatographic separation (mobile phase composition and column) and detection conditions using two ionisation sources: electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI). In order to correct matrix effects, a total of 20 surrogate/internal standards were used. ESI was found to have better sensitivity than APCI. Recoveries ranging from 79 to 134 % for tap water and 66 to 144 % for surface water were obtained. Intra-day precision, calculated as relative standard deviation, was below 34 % for tap water and below 21 % for surface water, groundwater and effluent wastewater. Method quantification limits (MQL) were in the low ng L(-1) range, except for the contrast agents iomeprol, amidotrizoic acid and iohexol (22, 25.5 and 17.9 ng L(-1), respectively). Finally, the method was applied to the analysis of 56 real water samples as part of the validation procedure. All of the compounds were detected in at least some of the water samples analysed. Graphical Abstract Multi-residue method for the determination of micropollutants including pharmaceuticals, iodinated contrast media and pesticides in waters by LC-MS/MS.

A peptidomic approach for monitoring and characterising peptide cyanotoxins produced in Italian lakes by matrix-assisted laser desorption/ionisation and quadrupole time-of-flight mass spectrometry.

PubMed

Ferranti, Pasquale; Nasi, Antonella; Bruno, Milena; Basile, Adriana; Serpe, Luigi; Gallo, Pasquale

2011-05-15

In recent years, the occurrence of cyanobacterial blooms in eutrophic freshwaters has been described all over the world, including most European countries. Blooms of cyanobacteria may produce mixtures of toxic secondary metabolites, called cyanotoxins. Among these, the most studied are microcystins, a group of cyclic heptapeptides, because of their potent hepatotoxicity and activity as tumour promoters. Other peptide cyanotoxins have been described whose structure and toxicity have not been thoroughly studied. Herein we present a peptidomic approach aimed to characterise and quantify the peptide cyanotoxins produced in two Italian lakes, Averno and Albano. The procedure was based on matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry mass spectrometry (MALDI-TOF-MS) analysis for rapid detection and profiling of the peptide mixture complexity, combined with liquid chromatography/electrospray ionisation quadrupole time-of- flight tandem mass spectrometry (LC/ESI-Q-TOF-MS/MS) which provided unambiguous structural identification of the main compounds, as well as accurate quantitative analysis of microcystins. In the case of Lake Averno, a novel variant of microcystin-RR and two novel anabaenopeptin variants (Anabaenopeptins B(1) and Anabaenopeptin F(1)), presenting homoarginine in place of the commonly found arginine, were detected and characterised. In Lake Albano, the peculiar peptide patterns in different years were compared, as an example of the potentiality of the peptidomic approach for fast screening analysis, prior to fine structural analysis and determination of cyanotoxins, which included six novel aeruginosin variants. This approach allows for wide range monitoring of cyanobacteria blooms, and to collect data for evaluating possible health risks to consumers, through the panel of the compounds produced along different years. Copyright © 2011 John Wiley & Sons, Ltd.

Streaming visualisation of quantitative mass spectrometry data based on a novel raw signal decomposition method

PubMed Central

Zhang, Yan; Bhamber, Ranjeet; Riba-Garcia, Isabel; Liao, Hanqing; Unwin, Richard D; Dowsey, Andrew W

2015-01-01

As data rates rise, there is a danger that informatics for high-throughput LC-MS becomes more opaque and inaccessible to practitioners. It is therefore critical that efficient visualisation tools are available to facilitate quality control, verification, validation, interpretation, and sharing of raw MS data and the results of MS analyses. Currently, MS data is stored as contiguous spectra. Recall of individual spectra is quick but panoramas, zooming and panning across whole datasets necessitates processing/memory overheads impractical for interactive use. Moreover, visualisation is challenging if significant quantification data is missing due to data-dependent acquisition of MS/MS spectra. In order to tackle these issues, we leverage our seaMass technique for novel signal decomposition. LC-MS data is modelled as a 2D surface through selection of a sparse set of weighted B-spline basis functions from an over-complete dictionary. By ordering and spatially partitioning the weights with an R-tree data model, efficient streaming visualisations are achieved. In this paper, we describe the core MS1 visualisation engine and overlay of MS/MS annotations. This enables the mass spectrometrist to quickly inspect whole runs for ionisation/chromatographic issues, MS/MS precursors for coverage problems, or putative biomarkers for interferences, for example. The open-source software is available from http://seamass.net/viz/. PMID:25663356

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Complete texts of 123 communications to the Congress (in the original language; the majority in English, some in Russian, French), on the following topics; radiation perspective in the U.S., radiation and man, non-ionising radiation, radiation effects on animals, radiation quantities, radioecology, reactor experience, late radiation effects, dose calculations and radiation accidents.

PAH Formation in O-rich Evolved Stars

NASA Astrophysics Data System (ADS)

Guzman-Ramirez, L.; Lagadec, E.; Jones, D.; Zijlstra, A. A.; Gesicki, K.

2015-08-01

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around these objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. Using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionised emission from the [S IV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionised material is mostly present in the inner parts, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

Determination of patulin in apple and derived products by UHPLC-MS/MS. Study of matrix effects with atmospheric pressure ionisation sources.

PubMed

Beltrán, Eduardo; Ibáñez, María; Sancho, Juan Vicente; Hernández, Félix

2014-01-01

Sensitive and reliable analytical methodology has been developed for the measurement of patulin in regulated foodstuffs by using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) with triple quadrupole analyser. Solid samples were extracted with ethyl acetate, while liquid samples were directly injected into the chromatographic system after dilution and filtration without any clean-up step. Chromatographic separation was achieved in less than 4min. Electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) sources were evaluated, in order to assess matrix effects. The use of ESI source caused strong signal suppression in samples; however, matrix effect was negligible using APCI, allowing quantification with calibration standards prepared in solvent. The method was validated in four different apple matrices (juice, fruit, puree and compote) at two concentrations at the low μgkg(-1) level. Average recoveries (n=5) ranged from 71% to 108%, with RSDs lower than 14%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inaccurate official assessment of radiofrequency safety by the Advisory Group on Non-ionising Radiation.

PubMed

Starkey, Sarah J

2016-12-01

The Advisory Group on Non-ionising Radiation (AGNIR) 2012 report forms the basis of official advice on the safety of radiofrequency (RF) electromagnetic fields in the United Kingdom and has been relied upon by health protection agencies around the world. This review describes incorrect and misleading statements from within the report, omissions and conflict of interest, which make it unsuitable for health risk assessment. The executive summary and overall conclusions did not accurately reflect the scientific evidence available. Independence is needed from the International Commission on Non-Ionizing Radiation Protection (ICNIRP), the group that set the exposure guidelines being assessed. This conflict of interest critically needs to be addressed for the forthcoming World Health Organisation (WHO) Environmental Health Criteria Monograph on Radiofrequency Fields. Decision makers, organisations and individuals require accurate information about the safety of RF electromagnetic signals if they are to be able to fulfil their safeguarding responsibilities and protect those for whom they have legal responsibility.

Effect of laser pulse repetition frequency on the optical breakdown threshold of quartz glass

NASA Astrophysics Data System (ADS)

Kononenko, T. V.; Schöneseiffen, S.; Konov, V. I.; Dausinger, F.

2013-08-01

The thresholds of optical breakdown in the volume of quartz glass were measured in relation to the number of pulses under irradiation by ultrashort laser pulses with different pulse repetition frequencies (1 - 400 kHz). Increasing this frequency from 10 to 400 kHz was found to substantially lower the breakdown threshold for 500-fs long pulses (at a wavelength of 1030 nm) and to lower to a smaller degree for 5-ps long pulses (515 nm). A strong frequency dependence of the breakdown threshold is observed under the same conditions as a manifold decrease of the breakdown threshold with increase in the number of pulses in a pulse train. The dependence of the optical breakdown on the number of pulses is attributable to the accumulation of point defects under multiple subthreshold irradiation, which affects the mechanism of collisional ionisation. In this case, the frequency dependence of the breakdown threshold of quartz glass is determined by the engagement of shortlived defects in the ionisation mechanism.

Electrospray ionisation mass spectrometry facilitates detection of fibrinogen (Bbeta 14 Arg --> Cys) mutation in a family with thrombosis.

PubMed

Brennan, S O; Hammonds, B; Spearing, R; George, P M

1997-12-01

We report the first direct detection of a fibrinogen mutation by electrospray ionisation mass spectrometry. The propositus, from a family with a history of thrombosis, came to attention after a pulmonary embolism subsequent to a spontaneous abortion. Prolonged thrombin (41 s) and reptilase times (26 s) together with an impairment of fibrinopeptide B release suggested a mutation at the thrombin cleavage site of the Bbeta chain. Direct mass analysis of purified fibrin chains from a thrombin induced clot showed that 50% of the Bbeta chains remained uncleaved. The measured mass of the mono sialo isoform of this uncleaved chain was 54150 Da, compared to a value of 54198 Da for normal Bbeta chains. This decrease of 48 Da in the intact protein is indicative of either a Bbeta 14 Arg to Cys, or Arg to Leu substitution. Heterozygosity for the Bbeta 14 Arg --> Cys mutation was verified by PCR amplification and DNA sequence analysis.

Protection from radon exposure at home and at work in the directive 2013/59/Euratom.

PubMed

Bochicchio, F

2014-07-01

In recent years, international organisations involved in radiation protection and public health have produced new guidance, recommendations and requirements aiming better protection from radon exposure. These organisations have often worked in close collaboration in order to facilitate the establishment of harmonised standards. This paper deals with such standards and specifically with the new European Council Directive of 5 December 2013 on basic safety standards for protection against the dangers arising from exposure to ionising radiation (2013/59/Euratom). This new Directive has established a harmonised framework for the protection against ionising radiations, including protection from radon exposure. Requirements for radon in workplace are much more tightening than in previous Directive, and exposures to radon in dwellings are regulated for the first time in a Directive. Radon-related articles of this Directive are presented and discussed in this paper, along with some comparisons with other relevant international standards. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Influence du traitement ionisant par rayonnement γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale

NASA Astrophysics Data System (ADS)

Stuyck, S.; Connaulte, J.; Lesgards, G.; Prost, M.; Raffi, J.

1998-04-01

Ionizing radiation of vegetables is a cleaning up and preservation physical treatment which consists in submitting them to γ radiation, X radiation or electrons beam. This study deals with the influence of γ radiation on antioxidative effect of vegetables polyphenolic parts. In that purpose, we use a simple biological test based on erythrocytes haemolysis. Le traitement ionisant des produits végétaux est un procédé physique d'assainissement et de conservation qui consiste à les soumettre à l'action de rayonnements γ, de rayons X ou de faisceaux d'électrons. Ce travail porte sur l'étude de l'influence des rayonnements γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale. Pour cela, un test biologique basé sur l'hémolyse d'érythrocytes est utilisé.

"Soft"or "hard" ionisation? Investigation of metastable gas temperature effect on direct analysis in real-time analysis of Voriconazole.

PubMed

Lapthorn, Cris; Pullen, Frank

2009-01-01

The performance of the direct analysis in real-time (DART) technique was evaluated across a range of metastable gas temperatures for a pharmaceutical compound, Voriconazole, in order to investigate the effect of metastable gas temperature on molecular ion intensity and fragmentation. The DART source has been used to analyse a range of analytes and from a range of matrices including drugs in solid tablet form and preparations, active ingredients in ointment, naturally occurring plant alkaloids, flavours and fragrances, from thin layer chromatography (TLC) plates, melting point tubes and biological matrices including hair, urine and blood. The advantages of this technique include rapid analysis time (as little as 5 s), a reduction in sample preparation requirements, elimination of mobile phase requirement and analysis of samples not typically amenable to atmospheric pressure ionisation (API) techniques. This technology has therefore been proposed as an everyday tool for identification of components in crude organic reaction mixtures.

Feedback and Feeding in the Context of Galaxy Evolution with SPICA: Direct Characterisation of Molecular Outflows and Inflows

NASA Astrophysics Data System (ADS)

González-Alfonso, E.; Armus, L.; Carrera, F. J.; Charmandaris, V.; Efstathiou, A.; Egami, E.; Fernández-Ontiveros, J. A.; Fischer, J.; Granato, G. L.; Gruppioni, C.; Hatziminaoglou, E.; Imanishi, M.; Isobe, N.; Kaneda, H.; Koziel-Wierzbowska, D.; Malkan, M. A.; Martín-Pintado, J.; Mateos, S.; Matsuhara, H.; Miniutti, G.; Nakagawa, T.; Pozzi, F.; Rico-Villas, F.; Rodighiero, G.; Roelfsema, P.; Spinoglio, L.; Spoon, H. W. W.; Sturm, E.; van der Tak, F.; Vignali, C.; Wang, L.

2017-11-01

A far-infrared observatory such as the SPace Infrared telescope for Cosmology and Astrophysics, with its unprecedented spectroscopic sensitivity, would unveil the role of feedback in galaxy evolution during the last 10 Gyr of the Universe (z = 1.5-2), through the use of far- and mid-infrared molecular and ionic fine structure lines that trace outflowing and infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni line shapes and absorption blueshifted wings in molecular lines with high dipolar moments, and through emission line wings of fine-structure lines of ionised gas. We quantify the detectability of galaxy-scale massive molecular and ionised outflows as a function of redshift in AGN-dominated, starburst-dominated, and main-sequence galaxies, explore the detectability of metal-rich inflows in the local Universe, and describe the most significant synergies with other current and future observatories that will measure feedback in galaxies via complementary tracers at other wavelengths.

Feline chronic renal failure: calcium homeostasis in 80 cases diagnosed between 1992 and 1995.

PubMed

Barber, P J; Elliott, J

1998-03-01

Eighty cats with chronic renal failure (CRF) were evaluated in a prospective study to investigate the prevalence and aetiopathogenesis of renal secondary hyperparathyroidism (RHPTH), using routine plasma biochemistry and assays of parathyroid hormone (PTH), blood ionised calcium and 1,25 dihydroxycholecalciferol (1,25[OH]2D3). Hyperparathyroidism was a frequent sequela of CRF, affecting 84 per cent of cats with CRF, the severity and prevalence of RHPTH increasing with the degree of renal dysfunction. Compared with an age-matched control population, plasma concentrations of phosphate and PTH were significantly higher and 1,25(OH)2D3 concentrations were significantly lower in the two groups of cats presenting with clinical signs of CRF. Significant ionised hypocalcaemia was present only in cats with end-stage renal failure. However, a number of cats were hyperparathyroid in the absence of abnormalities in the parameters of calcium homeostasis measured in this study. There was a significant correlation between plasma phosphate and PTH concentrations.

Characterization of peeled and unpeeled almond (Prunus amygdalus) flour after electron beam processing

NASA Astrophysics Data System (ADS)

Lanza, C. M.; Mazzaglia, A.; Paladino, R.; Auditore, L.; Barnà, R. C.; Loria, D.; Trifirò, A.; Trimarchi, M.; Bellia, G.

2013-05-01

Flours of unpeeled and peeled almond seeds have been irradiated with ionising radiation at 1.5 kGy dose by means of 5 MeV energy electron beam. The effects of ionising radiation have been studied concerning microbiological parameters, such as total mesophilic counts, mould, yeast, enterobacters, coliform bacteria, as well as physicochemical parameters, free fatty acid, peroxide number, humidity, activity water, aflatoxin, pesticides, and sensory evaluation of attributes regarding only appearance, olfactory and rheological aspects in accordance with the prescription of Italian laws about the consumption of irradiated food. The results, compared with non-irradiated samples from the same supply, show a sharp decrease of pathogen loads while no significant variations of physicochemical parameters and sensory descriptors have been noticed. These results indicate that irradiation at 1.5 kGy dose, lower than values usually reported in literature, seems to be still a suitable sanitation treatment to extend the shelf-life of this kind of foodstuff while maintaining its nutritional, safe and sensory characteristics.

Accurate mass measurement by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. II. Measurement of negative radical ions using porphyrin and fullerene standard reference materials.

PubMed

Shao, Zhecheng; Wyatt, Mark F; Stein, Bridget K; Brenton, A Gareth

2010-10-30

A method for the accurate mass measurement of negative radical ions by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is described. This is an extension to our previously described method for the accurate mass measurement of positive radical ions (Griffiths NW, Wyatt MF, Kean SD, Graham AE, Stein BK, Brenton AG. Rapid Commun. Mass Spectrom. 2010; 24: 1629). The porphyrin standard reference materials (SRMs) developed for positive mode measurements cannot be observed in negative ion mode, so fullerene and fluorinated porphyrin compounds were identified as effective SRMs. The method is of immediate practical use for the accurate mass measurement of functionalised fullerenes, for which negative ion MALDI-TOFMS is the principal mass spectrometry characterisation technique. This was demonstrated by the accurate mass measurement of six functionalised C(60) compounds. Copyright © 2010 John Wiley & Sons, Ltd.

A new processing scheme for ultra-high resolution direct infusion mass spectrometry data

NASA Astrophysics Data System (ADS)

Zielinski, Arthur T.; Kourtchev, Ivan; Bortolini, Claudio; Fuller, Stephen J.; Giorio, Chiara; Popoola, Olalekan A. M.; Bogialli, Sara; Tapparo, Andrea; Jones, Roderic L.; Kalberer, Markus

2018-04-01

High resolution, high accuracy mass spectrometry is widely used to characterise environmental or biological samples with highly complex composition enabling the identification of chemical composition of often unknown compounds. Despite instrumental advancements, the accurate molecular assignment of compounds acquired in high resolution mass spectra remains time consuming and requires automated algorithms, especially for samples covering a wide mass range and large numbers of compounds. A new processing scheme is introduced implementing filtering methods based on element assignment, instrumental error, and blank subtraction. Optional post-processing incorporates common ion selection across replicate measurements and shoulder ion removal. The scheme allows both positive and negative direct infusion electrospray ionisation (ESI) and atmospheric pressure photoionisation (APPI) acquisition with the same programs. An example application to atmospheric organic aerosol samples using an Orbitrap mass spectrometer is reported for both ionisation techniques resulting in final spectra with 0.8% and 8.4% of the peaks retained from the raw spectra for APPI positive and ESI negative acquisition, respectively.

A system for protecting the environment from ionising radiation: selecting reference fauna and flora, and the possible dose models and environmental geometries that could be applied to them.

PubMed

Pentreath, R J; Woodhead, D S

2001-09-28

In order to demonstrate, explicitly, that the environment can be protected with respect to controlled sources of ionising radiation, it is essential to have a systematic framework within which dosimetry models for fauna and flora can be used. And because of the practical limitations on what could reasonably be modelled and the amount of information that could reasonably be obtained, it is also necessary to limit the application of such models to a 'set' of fauna and flora within a reference' context. This paper, therefore, outlines the factors that will need to be considered to select such 'reference' fauna and flora, and describes some of the factors and constraints necessary to develop the associated dosimetry models. It also describes some of the most basic environmental geometrics within which the dose models could be set in order to make comparisons amongst different radiation sources.

Chemical profile of mango (Mangifera indica L.) using electrospray ionisation mass spectrometry (ESI-MS).

PubMed

Oliveira, Bruno G; Costa, Helber B; Ventura, José A; Kondratyuk, Tamara P; Barroso, Maria E S; Correia, Radigya M; Pimentel, Elisângela F; Pinto, Fernanda E; Endringer, Denise C; Romão, Wanderson

2016-08-01

Mangifera indica L., mango fruit, is consumed as a dietary supplement with purported health benefits; it is widely used in the food industry. Herein, the chemical profile of the Ubá mango at four distinct maturation stages was evaluated during the process of growth and maturity using negative-ion mode electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI(-)FT-ICR MS) and physicochemical characterisation analysis (total titratable acidity (TA), total soluble solids (TSS), TSS/TA ratio, and total polyphenolic content). Primary (organic acids and sugars) and secondary metabolites (polyphenolic compounds) were mostly identified in the third maturation stage, thus indicating the best stage for harvesting and consuming the fruit. In addition, the potential cancer chemoprevention of the secondary metabolites (phenolic extracts obtained from mango samples) was evaluated using the induction of quinone reductase activity, concluding that fruit polyphenols have the potential for cancer chemoprevention. Copyright © 2016 Elsevier Ltd. All rights reserved.

Acceptance Tests for AMS Radiocarbon Measurements at iThemba LABS, Gauteng, South Africa

NASA Astrophysics Data System (ADS)

Mbele, Vela L.; Mullins, Simon M.; Winkler, Stephan R.; Woodborne, Stephan

The accelerator mass spectrometer was commissioned recently at the iThemba LABS 6 MV tandem accelerator. Improvements in the vacuum system, requiring procurement of cryo-pumps and the reducing the tank pressure of the N2 + CO2 insulation gas mixture below the level used for IBA measurements, were necessary. This resulted in the reduction of the nitrogen background and improved the resolution of 14C from 14N background in the ionisation chamber. The nitrogen was leaking to the stripping canal because of inadequate sealing. The analysing magnet was scaled to detect C3+ ions, at 3 MV terminal potential. The first sensible spectra allowed for the pin-pointing of many persistent issues. This resulted in measurements with a precision better than 1 pMC, and current blank levels correspond to 12 half-lives of 14C or ∼68000 years. The radiocarbon sample preparation laboratory has reached production status. A brief outlook of the work towards the implementation of the measurement and chemical preparation protocols for radionuclides 10Be and 26Al is also summarised in the conclusion

ALPIDE: the Monolithic Active Pixel Sensor for the ALICE ITS upgrade

NASA Astrophysics Data System (ADS)

Šuljić, M.

2016-11-01

The upgrade of the ALICE vertex detector, the Inner Tracking System (ITS), is scheduled to be installed during the next long shutdown period (2019-2020) of the CERN Large Hadron Collider (LHC) . The current ITS will be replaced by seven concentric layers of Monolithic Active Pixel Sensors (MAPS) with total active surface of ~10 m2, thus making ALICE the first LHC experiment implementing MAPS detector technology on a large scale. The ALPIDE chip, based on TowerJazz 180 nm CMOS Imaging Process, is being developed for this purpose. A particular process feature, the deep p-well, is exploited so the full CMOS logic can be implemented over the active sensor area without impinging on the deposited charge collection. ALPIDE is implemented on silicon wafers with a high resistivity epitaxial layer. A single chip measures 15 mm by 30 mm and contains half a million pixels distributed in 512 rows and 1024 columns. In-pixel circuitry features amplification, shaping, discrimination and multi-event buffering. The readout is hit driven i.e. only addresses of hit pixels are sent to the periphery. The upgrade of the ITS presents two different sets of requirements for sensors of the inner and of the outer layers due to the significantly different track density, radiation level and active detector surface. The ALPIDE chip fulfils the stringent requirements in both cases. The detection efficiency is higher than 99%, fake-hit probability is orders of magnitude lower than the required 10-6 and spatial resolution within the required 5 μm. This performance is to be maintained even after a total ionising does (TID) of 2.7 Mrad and a non-ionising energy loss (NIEL) fluence of 1.7 × 1013 1 MeV neq/cm2, which is above what is expected during the detector lifetime. Readout rate of 100 kHz is provided and the power density of ALPIDE is less than 40 mW/cm2. This contribution will provide a summary of the ALPIDE features and main test results.

Modelling Dust Processing and Evolution in Extreme Environments as seen by Herschel Space Observatory

NASA Astrophysics Data System (ADS)

Bocchio, Marco

2014-09-01

The main goal of my PhD study is to understand the dust processing that occurs during the mixing between the galactic interstellar medium and the intracluster medium. This process is of particular interest in violent phenomena such as galaxy-galaxy interactions or the ``Ram Pressure Stripping'' due to the infalling of a galaxy towards the cluster centre.Initially, I focus my attention to the problem of dust destruction and heating processes, re-visiting the available models in literature. I particularly stress on the cases of extreme environments such as a hot coronal-type gas (e.g., IGM, ICM, HIM) and supernova-generated interstellar shocks. Under these conditions small grains are destroyed on short timescales and large grains are heated by the collisions with fast electrons making the dust spectral energy distribution very different from what observed in the diffuse ISM.In order to test our models I apply them to the case of an interacting galaxy, NGC 4438. Herschel data of this galaxy indicates the presence of dust with a higher-than-expected temperature.With a multi-wavelength analysis on a pixel-by-pixel basis we show that this hot dust seems to be embedded in a hot ionised gas therefore undergoing both collisional heating and small grain destruction.Furthermore, I focus on the long-standing conundrum about the dust destruction and dust formation timescales in the Milky Way. Based on the destruction efficiency in interstellar shocks, previous estimates led to a dust lifetime shorter than the typical timescale for dust formation in AGB stars. Using a recent dust model and an updated dust processing model we re-evaluate the dust lifetime in our Galaxy. Finally, I turn my attention to the phenomenon of ``Ram Pressure Stripping''. The galaxy ESO 137-001 represents one of the best cases to study this effect. Its long H2 tail embedded in a hot and ionised tail raises questions about its possible stripping from the galaxy or formation downstream in the tail. Based on recent hydrodynamical numerical simulations, I show that the formation of H2 molecules on the surface of dust grains in the tail is a viable scenario.

High-performance liquid chromatographic analysis of as-synthesised N,N'-dimethylformamide-stabilised gold nanoclusters product

NASA Astrophysics Data System (ADS)

Xie, Shunping; Paau, Man Chin; Zhang, Yan; Shuang, Shaomin; Chan, Wan; Choi, Martin M. F.

2012-08-01

Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of various Au atoms as well as DMF-stabilised ligands. Finally, the composition of the separated DMF-AuNCs was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and electrospray ionisation mass spectrometry, proving that the as-synthesised DMF-AuNCs product consists of Au10+, Au10, Au11, Au12, Au13, and Au14 NCs stabilised with various numbers of DMF ligands.Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of various Au atoms as well as DMF-stabilised ligands. Finally, the composition of the separated DMF-AuNCs was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and electrospray ionisation mass spectrometry, proving that the as-synthesised DMF-AuNCs product consists of Au10+, Au10, Au11, Au12, Au13, and Au14 NCs stabilised with various numbers of DMF ligands. This article was submitted as part of a Themed Issue on metallic clusters. Other papers on this topic can be found in issue 14 of vol. 4 (2012). This issue can be found from the Nanoscale homepage [http://www.rsc.org/nanoscale].

Globules and pillars in Cygnus X. II. Massive star formation in the globule IRAS 20319+3958

NASA Astrophysics Data System (ADS)

Djupvik, A. A.; Comerón, F.; Schneider, N.

2017-03-01

Globules and pillars, impressively revealed by the Spitzer and Herschel satellites, for example, are pervasive features found in regions of massive star formation. Studying their embedded stellar populations can provide an excellent laboratory to test theories of triggered star formation and the features that it may imprint on the stellar aggregates resulting from it. We studied the globule IRAS 20319+3958 in Cygnus X by means of visible and near-infrared imaging and spectroscopy, complemented with mid-infrared Spitzer/IRAC imaging, in order to obtain a census of its stellar content and the nature of its embedded sources. Our observations show that the globule contains an embedded aggregate of about 30 very young (≲1 Myr) stellar objects, for which we estimate a total mass of 90 M⊙. The most massive members are three systems containing early B-type stars. Two of them most likely produced very compact H II regions, one of them being still highly embedded and coinciding with a peak seen in emission lines characterising the photon dominated region (PDR). Two of these three systems are resolved binaries, and one of those contains a visible Herbig Be star. An approximate derivation of the mass function of the members of the aggregate gives hints of a slope at high masses shallower than the classical Salpeter slope, and a peak of the mass distribution at a mass higher than that at which the widely adopted log-normal initial mass function peaks. The emission distribution of H2 and Brγ, tracing the PDR and the ionised gas phase, respectively, suggests that molecular gas is distributed as a shell around the embedded aggregate, filled with centrally-condensed ionised gas. Both, the morphology and the low excitation of the H II region, indicate that the sources of ionisation are the B stars of the embedded aggregate, rather than the external UV field caused by the O stars of Cygnus OB2. The youth of the embedded cluster, combined with the isolation of the globule, suggests that star formation in the globule was triggered by the passage of the ionisation front. Based on observations from the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, the Nordic Optical Telescope, La Palma, and the IAC80 telescope, Tenerife.Full Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A37

EDTA: a synthetic draw solute for forward osmosis.

PubMed

Lutchmiah, Kerusha; Post, Jan W; Rietveld, Luuk C; Cornelissen, Emile R

2014-01-01

The draw solution is the driving force of the forward osmosis (FO) process; however, the solute loss of the draw solute to the feed side is a general, financial limitation for most applications. The anthropogenic amino acid ethylenediaminetetraacetic acid (EDTA) was investigated as a draw solution for FO. At concentrations of approximately 1.0 osmol/kg, EDTA demonstrated comparable water fluxes (Jv = 5.29 L/m(2) h) to the commonly used salt, NaCl (Jv = 4.86 L/m(2) h), and both produced better water fluxes than glucose (Jv = 3.46 L/m(2) h). EDTA showed the lowest solute loss with Js (reverse solute loss or solute leakage) = 0.54 g/m(2) h. The molecular weight, degree of ionisation and charge of EDTA played a major role in this efficiency and EDTA was therefore well rejected by the membrane, showing a low Js/Jv ratio of 0.10 g/L. Owing to the low solute loss of EDTA and its resistance to biodegradation, this compound has the potential to be used as a draw solute for FO during long periods without requiring much replenishment.

Rapid analytical procedure for determination of mineral oils in edible oil by GC-FID.

PubMed

Wrona, Magdalena; Pezo, Davinson; Nerin, Cristina

2013-12-15

A procedure for the determination of mineral oils in edible oil has been fully developed. The procedure consists of using a sulphuric acid-impregnated silica gel (SAISG) glass column to eliminate the fat matter. A chemical combustion of the fatty acids takes place, while the mineral oils are not affected by the sulphuric acid. The column is eluted with hexane using a vacuum pump and the final extract is concentrated and analysed by gas chromatography (GC) with flame ionisation detector (FID). The detection limit (LOD) and the quantification limit (LOQ) in hexane were 0.07 and 0.21 μg g(-1) respectively and the LOQ in vegetable oil was 1 μg g(-1). Only a few minutes were necessary for sample treatment to have a clean extract. The efficiency of the process, measured through the recoveries from spiked samples of edible oil was higher than 95%. The procedure has been applied to determine mineral oil in olive oil from the retailed market. Copyright © 2013 Elsevier Ltd. All rights reserved.

Status of the DRIFT-II Directional Dark Matter Detector

NASA Astrophysics Data System (ADS)

Ghag, Chamkaur

2006-10-01

DRIFT is a directional dark matter detection programme that utilises the fact that as the Earth rotates and revolves around the Sun, an annual and diurnal signal modulation could be detected as a result of relative motion between the Earth and the non-rotating WIMP halo. This would provide very strong evidience of WIMPs since such a signal could not be mimicked by background sources. DRIFT II is an array of gas filled time projection chambers (TPCs) with Multi Wire Proportional Counter (MWPC) readout. Signals from different types of events differ greatly, between nuclear and electron recoils for example, due to the amount of ionisation initially produced and recombination times. This provides phenomenal discrimination capabilities. The first module of the DRIFT-II detector was successfully installed underground at Boulby Mine, N. Yorkshire early last year and has proven very stable, collecting high quality calibration and WIMP data. Since then a second module has been installed and is also currently operational. This presentation will describe the status of the detector and will focus on the determination of neutron efficiency and gamma rejection factors.

Encapsulation of biological active phenolic compounds extracted from wine wastes in alginate-chitosan microbeads.

PubMed

Moschona, Alexandra; Liakopoulou-Kyriakides, Maria

2018-04-23

Grapes (Vitis vinifera) are produced in large amounts worldwide and mostly are used for winemaking. Their untreated wastes are rich in valuable secondary metabolites, such as phenolics. Thus, in this study, white and red wine wastes (Malagouzia and Syrah variety) were investigated for their added value phenolics, which were analysed by high performance liquid chromatography (HPLC) and electrospray ionisation-mass spectrometry (ESI/MS) and subsequently encapsulated in several polymers. Extracts from all wastes gave high amounts of total phenolics (13 ± 2.72-22 ± 2.69 mg g -1 ) and possessed high antioxidant activity (67-97%). In addition to their significant antibacterial activity against gram-negative and gram-positive bacteria, interesting results were also obtained from their anti-inflammatory and antiplatelet activity, in vitro. Encapsulation of the extracts was selective, leaving out most of sugars and other organic compounds when alginate-chitosan was used. Encapsulation efficiency recorded for all extracts ranged from 55% to 79%. Release studies were also performed in several solutions aiming in their commercial use in food and pharmaceutical industries.

Development of supported liquid membrane techniques for the monitoring of trace levels of organic pollutants in wastewaters and water purification systems

NASA Astrophysics Data System (ADS)

Msagati, Titus A. M.; Mamba, Bhekie B.

The supported liquid membrane (SLM) extraction technique has been developed and successfully used for the monitoring of trace quantities of ionisable organic contaminants, including 17β-estradiol and its metabolites, testosterones and their methyl ester derivatives, benzimidazole anthelmintic antibiotics and sulphonamides in aquatic systems. A number of parameters which control the mass transfer in the supported liquid membrane extraction process such as donor and acceptor pH, extraction time and the type of organic liquid membrane were optimised to enhance the efficiency of the liquid membrane in the removal of these compounds. The method developed gave very low detection limits (0.3 ng/l to 2.4 ng/l for 17β-estradiol and its metabolites; between 1 μg/l and 20 μg/l for sulphonamides; and between 0.1 ng/l and 10 ng/l for benzimidazole anthelmintic compounds). The SLM method showed good linearity, reproducibility and repeatability values and is therefore suitable for routine monitoring of such compounds in water and wastewater systems.

A novel Laser Ion Mobility Spectrometer

NASA Astrophysics Data System (ADS)

Göbel, J.; Kessler, M.; Langmeier, A.

2009-05-01

IMS is a well know technology within the range of security based applications. Its main advantages lie in the simplicity of measurement, along with a fast and sensitive detection method. Contemporary technology often fails due to interference substances, in conjunction with saturation effects and a low dynamic detection range. High throughput facilities, such as airports, require the analysis of many samples at low detection limits within a very short timeframe. High detection reliability is a requirement for safe and secure operation. In our present work we developed a laser based ion-mobility-sensor which shows several advantages over known IMS sensor technology. The goal of our research was to increase the sensitivity compared to the range of 63Ni based instruments. This was achieved with an optimised geometric drift tube design and a pulsed UV laser system at an efficient intensity. In this intensity range multi-photon ionisation is possible, which leads to higher selectivity in the ion-formation process itself. After high speed capturing of detection samples, a custom designed pattern recognition software toolbox provides reliable auto-detection capability with a learning algorithm and a graphical user interface.

Chemical synthesis and NMR characterization of structured polyunsaturated triacylglycerols.

PubMed

Fauconnot, Laëtitia; Robert, Fabien; Villard, Renaud; Dionisi, Fabiola

2006-02-01

The chemical synthesis of pure triacylglycerol (TAG) regioisomers, that contain long chain polyunsaturated fatty acids, such as arachidonic acid (AA) or docosahexaenoic acid (DHA), and saturated fatty acids, such as lauric acid (La) or palmitic acid (P), at defined positions, is described. A single step methodology using (benzotriazol-1-yloxy)-tripyrrolidinophosphonium hexafluorophosphate (PyBOP), an activator of carboxyl group commonly used in peptide synthesis and occasionally used in carboxylic acid esterification, has been developed for structured TAG synthesis. Identification of the fatty acyl chains for each TAG species was confirmed by atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) and fatty acid positional distribution was determined by (1)H and (13)C NMR spectra. The generic described procedures can be applied to a large variety of substrates and was used for the production of specific triacylglycerols of defined molecular structures, with high regioisomeric purity. Combination of MS and NMR was shown to be an efficient tool for structural analysis of TAG. In particular, some NMR signals were demonstrated to be regioisomer specific, allowing rapid positional analysis of LC-PUFA containing TAG.

Alkali metal cation complexation by 1,3-alternate, mono-ionisable calix[4]arene-benzocrown-6 compounds

DOE PAGES

Surowiec, Malgorzata A.; Custelcean, Radu; Surowiec, Kazimierz; ...

2014-04-23

Alkali metal cation extraction behavior for two series of 1,3-alternate, mono-ionizable calix[4]arene-benzocrown-6 compounds is examined. In Series 1, the proton-ionizable group is a substituent on the benzo group of the polyether ring that directs it away from the crown ether cavity. In Series 2, the proton-ionizable group is attached to one para position in the calixarene framework, thus positioning it over the crown ether ring. Competitive solvent extraction of alkali metal cations from aqueous solutions into chloroform shows high Cs+ efficiency and selectivity. Single-species extraction pH profiles of Cs+ for Series 1 and 2 ligands with the same proton-ionizable groupmore » are very similar. Thus, association of Cs+ with the calixcrown ring is more important than the the proton-ionizable group’s position in relation to the crown ether cavity. Solid-state structures are presented for two unionized ligands from Series 2, as is a crystal containing two different ionized ligand–Cs+ complexes.« less

CMOS sensors for atmospheric imaging

NASA Astrophysics Data System (ADS)

Pratlong, Jérôme; Burt, David; Jerram, Paul; Mayer, Frédéric; Walker, Andrew; Simpson, Robert; Johnson, Steven; Hubbard, Wendy

2017-09-01

Recent European atmospheric imaging missions have seen a move towards the use of CMOS sensors for the visible and NIR parts of the spectrum. These applications have particular challenges that are completely different to those that have driven the development of commercial sensors for applications such as cell-phone or SLR cameras. This paper will cover the design and performance of general-purpose image sensors that are to be used in the MTG (Meteosat Third Generation) and MetImage satellites and the technology challenges that they have presented. We will discuss how CMOS imagers have been designed with 4T pixel sizes of up to 250 μm square achieving good charge transfer efficiency, or low lag, with signal levels up to 2M electrons and with high line rates. In both devices a low noise analogue read-out chain is used with correlated double sampling to suppress the readout noise and give a maximum dynamic range that is significantly larger than in standard commercial devices. Radiation hardness is a particular challenge for CMOS detectors and both of these sensors have been designed to be fully radiation hard with high latch-up and single-event-upset tolerances, which is now silicon proven on MTG. We will also cover the impact of ionising radiation on these devices. Because with such large pixels the photodiodes have a large open area, front illumination technology is sufficient to meet the detection efficiency requirements but with thicker than standard epitaxial silicon to give improved IR response (note that this makes latch up protection even more important). However with narrow band illumination reflections from the front and back of the dielectric stack on the top of the sensor produce Fabry-Perot étalon effects, which have been minimised with process modifications. We will also cover the addition of precision narrow band filters inside the MTG package to provide a complete imaging subsystem. Control of reflected light is also critical in obtaining the required optical performance and this has driven the development of a black coating layer that can be applied between the active silicon regions.

Characterisation of Plasma Filled Rod Pinch electron beam diode operation

NASA Astrophysics Data System (ADS)

MacDonald, James; Bland, Simon; Chittenden, Jeremy

2016-10-01

The plasma filled rod pinch diode (aka PFRP) offers a small radiographic spot size and a high brightness source. It operates in a very similar to plasma opening switches and dense plasma focus devices - with a plasma prefill, supplied via a number of simple coaxial plasma guns, being snowploughed along a thin rod cathode, before detaching at the end. The aim of this study is to model the PFRP and understand the factors that affect its performance, potentially improving future output. Given the dependence on the PFRP on the prefill, we are making detailed measurements of the density (1015-1018 cm-3), velocity, ionisation and temperature of the plasma emitted from a plasma gun/set of plasma guns. This will then be used to provide initial conditions to the Gorgon 3D MHD code, and the dynamics of the entire rod pinch process studied.

Application of Microbiological Method Direct Epifluorescence Filter Techique/Aerobic Plate Count Agar in the Identification of Irradiated Herbs and Spices

PubMed Central

Di Schiavi, Maria Teresa; Foti, Marina; Mosconi, Maria Cristina; Mattiolo, Giuseppina; Cavallina, Roberta

2014-01-01

Irradiation is a preservation technology used to improve the safety and hygienic quality of food. Aim of this study was to assess the applicability and validity of the microbiological screening method direct epifluorescence filter technique (DEFT)/aerobic plate count (APC) (EN 13783:2001) for the identification of irradiated herbs and spices. Tests on non-irradiated and irradiated samples of dried herbs and spices were performed. The method was based on the comparison of APC and count obtained using DEFT. In accordance with the standard reference, this method is not applicable to samples with APC<103 colony forming units (CFU)/g and this is its main limit. The results obtained in our laboratories showed that in 50% of cases of non-irradiated samples and in 96% of the samples treated with ionising radiation, the method was not applicable due to a value of CFU/g <103. PMID:27800348

Fifteen symposia on microdosimetry: implications for modern particle-beam cancer radiotherapy.

PubMed

Wambersie, A; Menzel, H; Gueulette, J; Pihet, P

2015-09-01

The objective of microdosimetry was, and still is, to identify physical descriptions of the initial physical processes of ionising radiation interacting with biological matter which correlate with observed radiobiological effects with a view to improve the understanding of radiobiological mechanisms and effects. The introduction of therapy with particles starting with fast neutrons followed by negative pions, protons and light ions necessitated the application of biological weighting factors for absorbed dose in order to account for differences of the relative biological effectiveness (RBE). Dedicated radiobiological experiments in therapy beams with mammalian cells and with laboratory animals provided sets of RBE values which are used to evaluate empirical 'clinical RBE values'. The combination of such experiments with microdosimetric measurements in identical conditions offered the possibility to establish semi-empirical relationships between microdosimetric parameters and results of RBE studies. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Variation in nutritional quality and chemical composition of fresh strawberry fruit: combined effect of cultivar and storage.

PubMed

Dragišić Maksimović, Jelena; Poledica, Milena; Mutavdžić, Dragosav; Mojović, Miloš; Radivojević, Dragan; Milivojević, Jasminka

2015-03-01

Bioclimatic air ionisation system (BI) works by neutralising air pollutants and microorganisms by means of oxidation with "activated oxygen". We investigated the effects of storage on changes in weight loss, chemical and sensory fruit properties in eight cultivars of strawberries (Fragaria x ananassa Duch.). All cultivars were evaluated for their standard parameters of quality (soluble solids content, total acidity, vitamin C content, total antioxidant activity - TAC, total phenolic and anthocyanins content) at different store conditions: fresh fruits-control, cold stored (at 4 °C) fruits without controlled atmospheres and cold stored (at 4 °C) fruits in BI. The present study outlines that anthocyanins of the strawberries stored in BI were subjected to significant degradation. These strawberries have prolonged shelf-life accompanied by weight loss reduction, TAC increment, and sensory properties improvement in tested cultivars, retaining other nutritional fruit qualities.

Natural occurrence of ochratoxin A in wolfberry fruit wine marketed in China.

PubMed

Kuang, Ying; Qiu, Feng; Kong, Weijun; Yang, Meihua

2012-01-01

Wolfberry fruit wine (WFW) is widely used as a global functional food to improve the immune system and prevent human disease. A total of 36 bottled WFWs were randomly collected in China between 2005 and 2010. Samples were analysed for the presence of ochratoxin A (OTA) using immunoaffinity column (IAC) clean-up and high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Positive results were confirmed by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). The limit of detection (LOD), based on a signal-to-noise ratio of 3, was 0.05 ng mL⁻¹. Recoveries ranged from 78.3% to 94.7% and relative standard deviations from 1.1% to 4.3% within the spiking range of 0.2-20 ng mL⁻¹. OTA was detected in one sample, below the maximum allowable limit as established by the European community.

Nasal Electrophoresis

DTIC Science & Technology

1960-10-06

wadding turundaf? into the n^sal cavity, the location of the indifferent electrode in the region of the occipital ’foramen, etc.)« On the "basis of our... neuralgias öf the trieeKinal nerve. In these cases we use Ionisation with a solution of novocaine (4$) and dijnedrol (0.5*) according to the; second

VizieR Online Data Catalog: Radiative forces for stellar envelopes (Seaton, 1997)

NASA Astrophysics Data System (ADS)

Seaton, M. J.; Yan, Y.; Mihalas, D.; Pradhan, A. K.

2000-02-01

(1) Primary data files, stages.zz These files give data for the calculation of radiative accelerations, GRAD, for elements with nuclear charge zz. Data are available for zz=06, 07, 08, 10, 11, 12, 13, 14, 16, 18, 20, 24, 25, 26 and 28. Calculations are made using data from the Opacity Project (see papers SYMP and IXZ). The data are given for each ionisation stage, j. They are tabulated on a mesh of (T, Ne, CHI) where T is temperature, Ne electron density and CHI is abundance multiplier. The files include data for ionisation fractions, for each (T, Ne). The file contents are described in the paper ACC and as comments in the code add.f (2) Code add.f This reads a file stages.zz and creates a file acc.zz giving radiative accelerations averaged over ionisation stages. The code prompts for names of input and output files. The code, as provided, gives equal weights (as defined in the paper ACC) to all stages. Th weights are set in SUBROUTINE WEIGHTS, which could be changed to give any weights preferred by the user. The dependence of diffusion coefficients on ionisation stage is given by a function ZET, which is defined in SUBROUTINE ZETA. The expressions used for ZET are as given in the paper. The user can change that subroutine if other expressions are preferred. The output file contains values, ZETBAR, of ZET, averaged over ionisation stages. (3) Files acc.zz Radiative accelerations computed using add.f as provided. The user will need to run the code add.f only if it is required to change the subroutines WEIGHTS or ZETA. The contents of the files acc.zz are described in the paper ACC and in comments contained in the code add.f. (4) Code accfit.f This code gives gives radiative accelerations, and some related data, for a stellar model. Methods used to interpolate data to the values of (T, RHO) for the stellar model are based on those used in the code opfit.for (see the paper OPF). The executable file accfit.com runs accfit.f. It uses a list of files given in accfit.files (see that file for further description). The mesh used for the abundance-multiplier CHI on the output file will generally be finer than that used in the input files acc.zz. The mesh to be used is specified on a file chi.dat. For a test run, the stellar model used is given in the file 10000_4.2 (Teff=10000 K, LOG10(g)=4.2) The output file from that test run is acc100004.2. The contents of the output file are described in the paper ACC and as comments in the code accfit.f. (5) The code diff.f This code reads the output file (e.g. acc1000004.2) created by accfit.f. For any specified depth point in the model and value of CHI, it gives values of radiative accelerations, the quantity ZETBAR required for calculation of diffusion coefficients, and Rosseland-mean opacities. The code prompts for input data. It creates a file recording all data calculated. The code diff.f is intended for incorporation, as a set of subroutines, in codes for diffusion calculations. (1 data file).

Exploring the inner parsecs of active galactic nuclei using near-infrared high resolution polarimetric simulations with MontAGN

NASA Astrophysics Data System (ADS)

Grosset, L.; Rouan, D.; Gratadour, D.; Pelat, D.; Orkisz, J.; Marin, F.; Goosmann, R.

2018-04-01

Aims: In this paper we aim to constrain the properties of dust structures in the central first parsecs of active galactic nuclei (AGN). Our goal is to study the required optical depth and composition of different dusty and ionised structures. Methods: We developed a radiative transfer code called Monte Carlo for Active Galactic Nuclei (MontAGN), which is optimised for polarimetric observations in the infrared. With both this code and STOKES, designed to be relevant from the hard X-ray band to near-infrared wavelengths, we investigate the polarisation emerging from a characteristic model of the AGN environment. For this purpose, we compare predictions of our models with previous infrared observations of NGC 1068, and try to reproduce several key polarisation patterns revealed by polarisation mapping. Results: We constrain the required dust structures and their densities. More precisely, we find that the electron density inside the ionisation cone is about 2.0 × 109 m-3. With structures constituted of spherical grains of constant density, we also highlight that the torus should be thicker than 20 in term of K-band optical depth to block direct light from the centre. It should also have a stratification in density: a less dense outer rim with an optical depth at 2.2 μm typically between 0.8 and 4 for observing the double scattering effect previously proposed. Conclusions: We bring constraints on the dust structures in the inner parsecs of an AGN model supposed to describe NGC 1068. When compared to observations, this leads to an optical depth of at least 20 in the Ks band for the torus of NGC 1068, corresponding to τV ≈ 170, which is within the range of current estimation based on observations. In the future, we will improve our study by including non-uniform dust structures and aligned elongated grains to constrain other possible interpretations of the observations.

A new paradigm in personal dosimetry using LiF:Mg,Cu,P.

PubMed

Cassata, J R; Moscovitch, M; Rotunda, J E; Velbeck, K J

2002-01-01

The United States Navy has been monitoring personnel for occupational exposure to ionising radiation since 1947. Film was exclusively used until 1973 when thermoluminescence dosemeters were introduced and used to the present time. In 1994, a joint research project between the Naval Dosimetry Center, Georgetown University, and Saint Gobain Crystals and Detectors (formerly Bicron RMP formerly Harshaw TLD) began to develop a state of the art thermoluminescent dosimetry system. The study was conducted from a large-scale dosimetry processor point of view with emphasis on a systems approach. Significant improvements were achieved by replacing the LiF:Mg,Ti with LiF:Mg,Cu,P TL elements due to the significant sensitivity increase, linearity, and negligible hiding. Dosemeter filters were optimised for gamma and X ray energy discrimination using Monte Carlo modelling (MCNP) resulting in significant improvement in accuracy and precision. Further improvements were achieved through the use of neural-network based dose calculation algorithms. Both back propagation and functional link methods were implemented and the data compared with essentially the same results. Several operational aspects of the system are discussed, including (1) background subtraction using control dosemeters, (2) selection criteria for control dosemeters, (3) optimisation of the TLD readers, (4) calibration methodology, and (5) the optimisation of the heating profile.

Radiosensitization of Aspergillus niger and Penicillium chrysogenum using basil essential oil and ionizing radiation for food decontamination.

USDA-ARS?s Scientific Manuscript database

The Minimum Inhibitory Concentration (MIC) of basil oil, was determined for two pathogenic fungi of rice, Aspergillus niger and Penicillium chrysogenum. The antifungal activity of the basil oil in combination with ionising radiation was then investigated to determine if basil oil caused radiosensit...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voytchev, Miroslav; Ambrosi, P.; Behrens, R.

This paper presents IEC/SC 45B Radiation protection instrumentation and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

Theoretical survey on positronium formation and ionisation in positron atom scattering

NASA Technical Reports Server (NTRS)

Basu, Madhumita; Ghosh, A. S.

1990-01-01

The recent theoretical studies are surveyed and reported on the formation of exotic atoms in positron-hydrogen, positron-helium and positron-lithium scattering specially at intermediate energy region. The ionizations of these targets by positron impact was also considered. Theoretical predictions for both the processes are compared with existing measured values.

Experts workshop on the ecotoxicological risk assessment of ionizable organic chemicals: Towards a science-based framework for chemical assessment

EPA Science Inventory

There is a growing need to develop analytical methods and tools that can be applied to assess the environmental risks associated with charged, polar, and ionisable organic chemicals, such as those used as active pharmaceutical ingredients, biocides, and surface active chemicals. ...

Supersonic molecular beam-hyperthermal surface ionisation coupled with time-of-flight mass spectrometry applied to trace level detection of polynuclear aromatic hydrocarbons in drinking water for reduced sample preparation and analysis time.

PubMed

Davis, S C; Makarov, A A; Hughes, J D

1999-01-01

Analysis of sub-ppb levels of polynuclear aromatic hydrocarbons (PAHs) in drinking water by high performance liquid chromatography (HPLC) fluorescence detection typically requires large water samples and lengthy extraction procedures. The detection itself, although selective, does not give compound identity confirmation. Benchtop gas chromatography/mass spectrometry (GC/MS) systems operating in the more sensitive selected ion monitoring (SIM) acquisition mode discard spectral information and, when operating in scanning mode, are less sensitive and scan too slowly. The selectivity of hyperthermal surface ionisation (HSI), the high column flow rate capacity of the supersonic molecular beam (SMB) GC/MS interface, and the high acquisition rate of time-of-flight (TOF) mass analysis, are combined here to facilitate a rapid, specific and sensitive technique for the analysis of trace levels of PAHs in water. This work reports the advantages gained by using the GC/HSI-TOF system over the HPLC fluorescence method, and discusses in some detail the nature of the instrumentation used.

The role of pyrimidine and water as underlying molecular constituents for describing radiation damage in living tissue: A comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuss, M. C.; Ellis-Gibbings, L.; Jones, D. B.

Water is often used as the medium for characterizing the effects of radiation on living tissue. However, in this study, charged-particle track simulations are employed to quantify the induced physicochemical and potential biological implications when a primary ionising particle with energy 10 keV strikes a medium made up entirely of water or pyrimidine. Note that pyrimidine was chosen as the DNA/RNA bases cytosine, thymine, and uracil can be considered pyrimidine derivatives. This study aims to assess the influence of the choice of medium on the charged-particle transport, and identify how appropriate it is to use water as the default medium tomore » describe the effects of ionising radiation on living tissue. Based on the respective electron interaction cross sections, we provide a model, which allows the study of radiation effects not only in terms of energy deposition (absorbed dose and stopping power) but also in terms of the number of induced molecular processes. Results of these parameters for water and pyrimidine are presented and compared.« less

Quality evaluation of Desmodium styracifolium using high-performance liquid chromatography with photodiode array detection and electrospray ionisation tandem mass spectrometry.

PubMed

Zhou, Chan; Luo, Jian-Guang; Kong, Ling-Yi

2012-01-01

Desmodium styracifolium, with C-flavone glycosides as main pharmacological effective compounds, is a popular Chinese medicinal herb and has been used to treat urination disturbance, urolithiasis, edema and jaundice. However, few systematic methods have been reported on the quality control of this natural herb. To develop a method for control the quality of D. styracifolium by combining chromatographic fingerprints and major constituent quantification. Separations were performed on an Ultimate XB-C-18 column by gradient elution using acetonitrile and 0.1% aqueous formic acid. Analytes were identified by HPLC coupled with electrospray ionisation mass spectrometry experiments. Twenty common peaks in chromatographic fingerprints were first identified among 15 batches of D. styracifolium from various regions. On basis of this, a HPLC-PAD method was established to simultaneously quantify five major constituents, which was validated for limit of qualification, linearity and interday variation of precision and accuracy. The assay developed could be considered as a suitable quality control method of D. styracifolium. Copyright © 2011 John Wiley & Sons, Ltd.

IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Discharge characteristics in a nonchain HF(DF) laser

NASA Astrophysics Data System (ADS)

Apollonov, V. V.; Kazantsev, S. Yu; Saifulin, A. V.; Firsov, K. N.

2000-06-01

It is found that for SF6—hydrocarbon (deuterocarbon) mixtures having a composition typical for nonchain HF(DF) lasers, the electric field strength reduced to the partial pressure of SF6 (pSF6) in the quasistationary phase of a volume self-sustained discharge (E/pSF6)st=92 V m-1 Pa-1 is close to the known critical value (E/p)cr=89 V m-1 Pa-1, which is specified by the condition that the electron-impact ionisation rate of SF6 is equal to the rate of electron attachment to SF6 molecules. This testifies to the decisive role of these two processes and allows the use of the known approximations of the effective ionisation coefficient and the electron drift velocity for pure SF6 when calculating the discharge characteristics. The oscilloscope traces of voltage and current calculated in this approximation for lasers with apertures ranging from 4 to 27 cm deviated from the experimental data by no more than 10%.

Modelling Photoelectron Production in the Enceladus Plume and Comparison with Observations by CAPS-ELS

NASA Astrophysics Data System (ADS)

Taylor, S. A.; Coates, A. J.; Jones, G.; Wellbrock, A.; Waite, J. H., Jr.

2016-12-01

The Electron Spectrometer (ELS) of the Cassini Plasma Spectrometer (CAPS) measures electrons in the energy range 0.6-28,000 eV with an energy resolution of 16.7%. ELS has observed photoelectrons produced in the plume of Enceladus. These photoelectrons are found during Enceladus encounters in the energetic particle shadow where the spacecraft is shielded from penetrating radiation by the moon [Coates et al, 2013]. Observable is a population of photoelectrons at 20-30eV, which are seen at other bodies in the solar system and are usually associated with ionisation by the strong solar He II (30.4 nm) line. We have identified secondary peaks at 40-50eV detected by ELS which are also interpreted as a warmer population of photoelectrons created through the ionisation of neutrals in the Enceladus torus. We have constructed a model of photoelectron production in the plume and compared it with ELS Enceladus flyby data using automated fitting procedures. This has yielded estimates for electron temperature and density as well as a spacecraft potential estimate which is corrected for.

Multichannel dosemeter and Al2O3:C optically stimulated luminescence fibre sensors for use in radiation therapy: evaluation with electron beams.

PubMed

Magne, S; Auger, L; Bordy, J M; de Carlan, L; Isambert, A; Bridier, A; Ferdinand, P; Barthe, J

2008-01-01

This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve.

3He Abundances in Planetary Nebulae

NASA Astrophysics Data System (ADS)

Guzman-Ramirez, Lizette

2017-10-01

Determination of the 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in stars which evolve through the planetary nebula phase. Planetary nebulae are the final evolutionary phase of low- and intermediate-mass stars, where the extensive mass lost by the star on the asymptotic giant branch is ionised by the emerging white dwarf. This ejecta quickly disperses and merges with the surrounding ISM. 3He abundances in planetary nebulae have been derived from the hyperfine transition of the ionised 3He, 3He+, at the radio rest frequency 8.665 GHz. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. Many hours have been put into trying to detect this line, using telescopes like the Effelsberg 100m dish of the Max Planck Institute for Radio Astronomy, the National Radio Astronomy Observatory (NRAO) 140-foot telescope, the NRAO Very Large Array, the Arecibo antenna, the Green Bank Telescope, and only just recently, the Deep Space Station 63 antenna from the Madrid Deep Space Communications Complex.

Chemical analysis of bleach and hydroxide-based solutions after decontamination of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX).

PubMed

Hopkins, F B; Gravett, M R; Self, A J; Wang, M; Chua, Hoe-Chee; Hoe-Chee, C; Lee, H S Nancy; Sim, N Lee Hoi; Jones, J T A; Timperley, C M; Riches, J R

2014-08-01

Detailed chemical analysis of solutions used to decontaminate chemical warfare agents can be used to support verification and forensic attribution. Decontamination solutions are amongst the most difficult matrices for chemical analysis because of their corrosive and potentially emulsion-based nature. Consequently, there are relatively few publications that report their detailed chemical analysis. This paper describes the application of modern analytical techniques to the analysis of decontamination solutions following decontamination of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX). We confirm the formation of N,N-diisopropylformamide and N,N-diisopropylamine following decontamination of VX with hypochlorite-based solution, whereas they were not detected in extracts of hydroxide-based decontamination solutions by nuclear magnetic resonance (NMR) spectroscopy or gas chromatography-mass spectrometry. We report the electron ionisation and chemical ionisation mass spectroscopic details, retention indices, and NMR spectra of N,N-diisopropylformamide and N,N-diisopropylamine, as well as analytical methods suitable for their analysis and identification in solvent extracts and decontamination residues.

Tolerance to Ammonia of Thulinius ruffoi (Bertolani, 1981), a Tardigrade Isolated from a Sewage Treatment Plant.

PubMed

Sobczyk, Mateusz; Michno, Klaudia; Kosztyła, Paulina; Stec, Daniel; Michalczyk, Łukasz

2015-12-01

The acute toxicity of ammonia on Thulinius ruffoi (Bertolani, 1981), a eutardigrade isolated from a small waste water treatment plant (WWTP) in Poland, was estimated. Our results show that no active individuals survived a 24 h exposure to solutions equal to or higher than 125 mg/L of total ammonia nitrogen (NH3-N + NH4 (+)-N), which, under the conditions in our experiment, was equivalent to 1.17 mg/L of un-ionised ammonia (NH3). The LC50 concentration of total ammonia nitrogen was equal to 52 mg/L (or 0.65 mg/L un-ionised ammonia). Given that the norms for the concentration of ammonia in treated waters leaving WWTPs are usually several times lower than the LC50 for T. ruffoi, this species does not seem to be a good bioindicator candidate for WWTPs. In this paper we also note that various ecotoxicological studies use different methodological approaches and we suggest that a more uniform methodology may aid interspecific comparisons of LC50 values.

Determination of fluspirilene in human plasma by liquid chromatography-tandem mass spectrometry with electrospray ionisation.

PubMed

Swart, K J; Sutherland, F C; van Essen, G H; Hundt, H K; Hundt, A F

1998-12-18

An ultra-sensitive method for the determination of fluspirilene in plasma was established, using high-performance liquid chromatographic separation with tandem mass spectrometric detection. The samples were extracted with hexane/isoamyl alcohol, separated on a Phenomenex Luna C18 5 mu 150 x 2.1 mm column with a mobile phase consisting of methanol-water-acetic acid (600:400:1) at a flow-rate of 0.3 ml/min. Detection was achieved by a Finnigan Matt mass spectrometer (LCQ) at unit resolution in full scan mode scanning the product ion spectrum from m/z 130-500 and monitoring the transition of the protonated molecular ion at m/z 476.2, to the sum of the largest product ions m/z 371, 342 and 274 (MS-MS). Electrospray ionisation was used for ion production. The mean recovery for fluspirilene was 90% with a lower limit of quantification of 21.50 pg/ml using 1 ml plasma for extraction. This is the first chromatographic method described for the determination of fluspirilene in plasma that is accurate and sensitive enough to be used in pharmacokinetic studies.

Resolving the Large Scale Spectral Variability of the Luminous Seyfert 1 Galaxy 1H 0419-577

NASA Technical Reports Server (NTRS)

Pounds, K. A.; Reeves, J. N.; Page, K. L.; OBrien, P. T.

2004-01-01

An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 in September 2002, when the source was in an extreme low-flux state, found a very hard X-ray spectrum at 1-10 keV with a strong soft excess below approximately 1 keV. Comparison with an earlier XMM-Newton observation when 1H 0419-577 was X-ray bright indicated the dominant spectral variability was due to a steep power law or cool Comptonized thermal emission. Four further XMM-Newton observations, with 1H 0419-577 in intermediate flux states, now support that conclusion, while we also find the variable emission component in intermediate state difference spectra to be strongly modified by absorption in low ionisation matter. The variable soft excess is seen to be an artefact of absorption of the underlying continuum while the core soft emission is attributed to recombination in an extended region of more highly ionised gas. This new analysis underlines the importance of fully accounting for absorption in characterizing AGN X-ray spectra.

Confronting the Gaia and NLTE spectroscopic parallaxes for the FGK stars

NASA Astrophysics Data System (ADS)

Sitnova, Tatyana; Mashonkina, Lyudmila; Pakhomov, Yury

2018-04-01

The understanding of the chemical evolution of the Galaxy relies on the stellar chemical composition. Accurate atmospheric parameters is a prerequisite of determination of accurate chemical abundances. For late type stars with known distance, surface gravity (log g) can be calculated from well-known relation between stellar mass, T eff, and absolute bolometric magnitude. This method weakly depends on model atmospheres, and provides reliable log g. However, accurate distances are available for limited number of stars. Another way to determine log g for cool stars is based on ionisation equilibrium, i.e. consistent abundances from lines of neutral and ionised species. In this study we determine atmospheric parameters moving step-by-step from well-studied nearby dwarfs to ultra-metal poor (UMP) giants. In each sample, we select stars with the most reliable T eff based on photometry and the distance-based log g, and compare with spectroscopic gravity calculated taking into account deviations from local thermodinamic equilibrium (LTE). After that, we apply spectroscopic method of log g determination to other stars of the sample with unknown distances.

An investigation of the matrix sensitivity of refinery gas analysis using gas chromatography with flame ionisation detection.

PubMed

Ferracci, Valerio; Brown, Andrew S; Harris, Peter M; Brown, Richard J C

2015-02-27

The response of a flame ionisation detector (FID) on a gas chromatograph to methane, ethane, propane, i-butane and n-butane in a series of multi-component refinery gas standards was investigated to assess the matrix sensitivity of the instrument. High-accuracy synthetic gas standards, traceable to the International System of Units, were used to minimise uncertainties. The instrument response exhibited a small dependence on the component amount fraction: this behaviour, consistent with that of another FID, was thoroughly characterised over a wide range of component amount fractions and was shown to introduce a negligible bias in the analysis of refinery gas samples, provided a suitable reference standard is employed. No significant effects of the molar volume, density and viscosity of the gas mixtures on the instrument response were observed, indicating that the FID is suitable for the analysis of refinery gas mixtures over a wide range of component amount fractions provided that appropriate drift-correction procedures are employed. Copyright © 2015 Elsevier B.V. All rights reserved.

Accurate mass measurement by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. I. Measurement of positive radical ions using porphyrin standard reference materials.

PubMed

Griffiths, Nia W; Wyatt, Mark F; Kean, Suzanna D; Graham, Andrew E; Stein, Bridget K; Brenton, A Gareth

2010-06-15

A method for the accurate mass measurement of positive radical ions by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is described. Initial use of a conjugated oligomeric calibration material was rejected in favour of a series of meso-tetraalkyl/tetraalkylaryl-functionalised porphyrins, from which the two calibrants required for a particular accurate mass measurement were chosen. While all measurements of monoisotopic species were within +/-5 ppm, and the method was rigorously validated using chemometrics, mean values of five measurements were used for extra confidence in the generation of potential elemental formulae. Potential difficulties encountered when measuring compounds containing multi-isotopic elements are discussed, where the monoisotopic peak is no longer the lowest mass peak, and a simple mass-correction solution can be applied. The method requires no significant expertise to implement, but care and attention is required to obtain valid measurements. The method is operationally simple and will prove useful to the analytical chemistry community. Copyright (c) 2010 John Wiley & Sons, Ltd.

Le Laser A Argon Ionise : Applications Therapeutiques

NASA Astrophysics Data System (ADS)

Brunetaud, J. M.; Mosquet, L.; Mordon, S.; Rotteleur, G.

1984-03-01

Le laser a argon ionise est un laser a emission continue, reglee en general en multiraies de 487 a 544 nm. Le rayonnement de ce laser est bien absorbe par les tissus vivants, avec une action preferentielle au niveau des pigments rouges (hemoglobine, myoglobine) et noirs (melanine). Le laser a argon est princi-palement utilise en therapeutique pour ses effets thermiques : en fonction du choix des parametres (puissance optique, surface exposee, temps d'exposition) on peut obtenir une coagulation (temperature optimale au niveau des tissus 60° - 80°) ou une volatisation (temperature superieure a 100°). Si la zone volatilisee est tres etroite (inferieure a 0,5 mm) on obtient un effet de coupe. Par rapport aux deux autres lasers egalement utilises pour leurs effets thermiques (CO2 et Nd. YAG) l'argon a des effets intermediaires : la coagulation sera plus superficielle qu'avec le Nd. YAG et la volatisation plus profonde qu'avec le CO2. Lors de la coupe, la necrose sur les berges sera egalement plus importante qu'avec le CO2.

AN EVALUATION OF THE BASIC CHARACTERISTICS OF A PLASTIC SCINTILLATING FIBRE DETECTOR IN CT RADIATION FIELDS.

PubMed

Terasaki, Kento; Fujibuchi, Toshioh; Toyoda, Takatoshi; Yoshida, Yutaka; Akasaka, Tsutomu; Nohtomi, Akihiro; Morishita, Junji

2016-12-01

The ionisation chamber for computed tomography (CT) is an instrument that is most commonly used to measure the computed tomography dose index. However, it has been reported that the 10 cm effective detection length of the ionisation chamber is insufficient due to the extent of the dose distribution outside the chamber. The purpose of this study was to estimate the basic characteristics of a plastic scintillating fibre (PSF) detector with a long detection length of 50 cm in CT radiation fields. The authors investigated position dependence using diagnostic X-ray equipment and dependencies for energy, dose rate and slice thickness using an X-ray CT system. The PSF detector outputs piled up at a count rate of 10 000 counts ms -1 in dose rate dependence study. With calibration, this detector may be useful as a CT dosemeter with a long detection length except for the measurement at high dose rate. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Comparison of the performance of different instruments in the stray neutron field around the CERN Proton Synchrotron.

PubMed

Aza, Eleni; Caresana, Marco; Cassell, Christopher; Colombo, Valeria; Damjanovic, Sanja; Gilardoni, Simone; Manessi, Giacomo Paolo; Pangallo, Michel; Perrin, Daniel; Silari, Marco

2014-10-01

This paper discusses an intercomparison campaign carried out in several locations around the CERN Proton Synchrotron. The locations were selected in order to perform the measurements in different stray field conditions. Various neutron detectors were employed: ionisation chambers, conventional and extended range rem counters, both commercial and prototype ones, including a novel instrument called LUPIN, specifically conceived to work in pulsed fields. The attention was focused on the potential differences in the instrument readings due to dead-time losses that are expected to affect most commercial units. The results show that the ionisation chambers and LUPIN agree well with the expected H*(10) values, as derived from FLUKA simulations, showing no relevant underestimations even in strongly pulsed fields. On the contrary, the dead-time losses of the other rem counters induced an underestimation in pulsed fields that was more important for instruments characterised by a higher dead time. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Molecular outflow and feedback in the obscured quasar XID2028 revealed by ALMA

NASA Astrophysics Data System (ADS)

Brusa, M.; Cresci, G.; Daddi, E.; Paladino, R.; Perna, M.; Bongiorno, A.; Lusso, E.; Sargent, M. T.; Casasola, V.; Feruglio, C.; Fraternali, F.; Georgiev, I.; Mainieri, V.; Carniani, S.; Comastri, A.; Duras, F.; Fiore, F.; Mannucci, F.; Marconi, A.; Piconcelli, E.; Zamorani, G.; Gilli, R.; La Franca, F.; Lanzuisi, G.; Lutz, D.; Santini, P.; Scoville, N. Z.; Vignali, C.; Vito, F.; Rabien, S.; Busoni, L.; Bonaglia, M.

2018-04-01

We imaged, with ALMA and ARGOS/LUCI, the molecular gas and dust and stellar continuum in XID2028, which is an obscured quasi-stellar object (QSO) at z = 1.593, where the presence of a massive outflow in the ionised gas component traced by the [OIII]5007 emission has been resolved up to 10 kpc. This target represents a unique test case to study QSO feedback in action at the peak epoch of AGN-galaxy co-evolution. The QSO was detected in the CO(5 - 4) transition and in the 1.3 mm continuum at 30 and 20σ significance, respectively; both emissions are confined in the central (<2 kpc) radius area. Our analysis suggests the presence of a fast rotating molecular disc (v 400 km s-1) on very compact scales well inside the galaxy extent seen in the rest-frame optical light ( 10 kpc, as inferred from the LUCI data). Adding available measurements in additional two CO transitions, CO(2 - 1) and CO(3 - 2), we could derive a total gas mass of 1010 M⊙, thanks to a critical assessment of CO excitation and the comparison with the Rayleigh-Jeans continuum estimate. This translates into a very low gas fraction (<5%) and depletion timescales of 40-75 Myr, reinforcing the result of atypical gas consumption conditions in XID2028, possibly because of feedback effects on the host galaxy. Finally, we also detect the presence of high velocity CO gas at 5σ, which we interpret as a signature of galaxy-scale molecular outflow that is spatially coincident with the ionised gas outflow. XID2028 therefore represents a unique case in which the measurement of total outflowing mass, of 500-800 M⊙ yr-1 including the molecular and atomic components in both the ionised and neutral phases, was attempted for a high-z QSO.

Novel methods for the quantification of (2E)-hexadecenal by liquid chromatography with detection by either ESI QTOF tandem mass spectrometry or fluorescence measurement.

PubMed

Lüth, Anja; Neuber, Corinna; Kleuser, Burkhard

2012-04-13

Sphingosine-1-phosphate lyase (SPL) is the only known enzyme that irreversibly cleaves sphingosine-1-phosphate (S1P) into phosphoethanolamine and (2E)-hexadecenal during the final step of sphingolipid catabolism. Because S1P is involved in a wide range of physiological and diseased processes, determining the activity of the degrading enzyme is of great interest. Therefore, we developed two procedures based on liquid chromatography (LC) for analysing (2E)-hexadecenal, which is one of the two S1P degradation products. After separation, two different quantification methods were performed, tandem mass spectrometry (MS) and fluorescence detection. However, (2E)-hexadecenal as a long-chain aldehyde is not ionisable by electrospray ionisation (ESI) for MS quantification and has an insufficient number of corresponding double bonds for fluorescence detection. Therefore, we investigated 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) as a derivatisation reagent. DAIH transforms the aldehyde into an ionisable and fluorescent analogue for quantitative analysis. Our conditions were optimised to obtain the outstanding limit of detection (LOD) of 1 fmol per sample (30 μL) for LC-MS/MS and 0.75 pmol per sample (200 μL) for LC determination with fluorescence detection. We developed an extraction procedure to separate and concentrate (2E)-hexadecenal from biological samples for these measurements. To confirm our new methods, we analysed the (2E)-hexadecenal level of different cell lines and human plasma for the first time ever. Furthermore, we treated HT-29 cells with different concentrations of 4-deoxypyridoxine (DOP), which competitively inhibits pyridoxal-5-phosphate (P5P), an essential cofactor for SPL activity, and observed a significant decrease in (2E)-hexadecenal relative to the untreated cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Generic sample preparation combined with high-resolution liquid chromatography-time-of-flight mass spectrometry for unification of urine screening in doping-control laboratories.

PubMed

Peters, R J B; Oosterink, J E; Stolker, A A M; Georgakopoulos, C; Nielen, M W F

2010-04-01

A unification of doping-control screening procedures of prohibited small molecule substances--including stimulants, narcotics, steroids, beta2-agonists and diuretics--is highly urgent in order to free resources for new classes such as banned proteins. Conceptually this may be achieved by the use of a combination of one gas chromatography-time-of-flight mass spectrometry method and one liquid chromatography-time-of-flight mass spectrometry method. In this work a quantitative screening method using high-resolution liquid chromatography in combination with accurate-mass time-of-flight mass spectrometry was developed and validated for determination of glucocorticosteroids, beta2-agonists, thiazide diuretics, and narcotics and stimulants in urine. To enable the simultaneous isolation of all the compounds of interest and the necessary purification of the resulting extracts, a generic extraction and hydrolysis procedure was combined with a solid-phase extraction modified for these groups of compounds. All 56 compounds are determined using positive electrospray ionisation with the exception of the thiazide diuretics for which the best sensitivity was obtained by using negative electrospray ionisation. The results show that, with the exception of clenhexyl, procaterol, and reproterol, all compounds can be detected below the respective minimum required performance level and the results for linearity, repeatability, within-lab reproducibility, and accuracy show that the method can be used for quantitative screening. If qualitative screening is sufficient the instrumental analysis may be limited to positive ionisation, because all analytes including the thiazides can be detected at the respective minimum required levels in the positive mode. The results show that the application of accurate-mass time-of-flight mass spectrometry in combination with generic extraction and purification procedures is suitable for unification and expansion of the window of screening methods of doping laboratories. Moreover, the full-scan accurate-mass data sets obtained still allow retrospective examination for emerging doping agents, without re-analyzing the samples.

Ionising Radiation Immediately Impairs Synaptic Plasticity-Associated Cytoskeletal Signalling Pathways in HT22 Cells and in Mouse Brain: An In Vitro/In Vivo Comparison Study

PubMed Central

Kempf, Stefan J.; Buratovic, Sonja; von Toerne, Christine; Moertl, Simone; Stenerlöw, Bo; Hauck, Stefanie M.; Atkinson, Michael J.; Eriksson, Per; Tapio, Soile

2014-01-01

Patients suffering from brain malignancies are treated with high-dose ionising radiation. However, this may lead to severe learning and memory impairment. Preventive treatments to minimise these side effects have not been possible due to the lack of knowledge of the involved signalling pathways and molecular targets. Mouse hippocampal neuronal HT22 cells were irradiated with acute gamma doses of 0.5 Gy, 1.0 Gy and 4.0 Gy. Changes in the cellular proteome were investigated by isotope-coded protein label technology and tandem mass spectrometry after 4 and 24 hours. To compare the findings with the in vivo response, male NMRI mice were irradiated on postnatal day 10 with a gamma dose of 1.0 Gy, followed by evaluation of the cellular proteome of hippocampus and cortex 24 hours post-irradiation. Analysis of the in vitro proteome showed that signalling pathways related to synaptic actin-remodelling were significantly affected at 1.0 Gy and 4.0 Gy but not at 0.5 Gy after 4 and 24 hours. We observed radiation-induced reduction of the miR-132 and Rac1 levels; miR-132 is known to regulate Rac1 activity by blocking the GTPase-activating protein p250GAP. In the irradiated hippocampus and cortex we observed alterations in the signalling pathways similar to those in vitro. The decreased expression of miR-132 and Rac1 was associated with an increase in hippocampal cofilin and phospho-cofilin. The Rac1-Cofilin pathway is involved in the modulation of synaptic actin filament formation that is necessary for correct spine and synapse morphology to enable processes of learning and memory. We suggest that acute radiation exposure leads to rapid dendritic spine and synapse morphology alterations via aberrant cytoskeletal signalling and processing and that this is associated with the immediate neurocognitive side effects observed in patients treated with ionising radiation. PMID:25329592

The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. I. Homogeneous set of atmospheric parameters

NASA Astrophysics Data System (ADS)

Mashonkina, L.; Jablonka, P.; Pakhomov, Yu.; Sitnova, T.; North, P.

2017-08-01

We present a homogeneous set of accurate atmospheric parameters for a complete sample of very and extremely metal-poor stars in the dwarf spheroidal galaxies (dSphs) Sculptor, Ursa Minor, Sextans, Fornax, Boötes I, Ursa Major II, and Leo IV. We also deliver a Milky Way (MW) comparison sample of giant stars covering the - 4 < [Fe/H] < - 1.7 metallicity range. We show that, in the [Fe/H] ≿ - 3.7 regime, the non-local thermodynamic equilibrium (NLTE) calculations with non-spectroscopic effective temperature (Teff) and surface gravity (log g) based on the photometric methods and known distance provide consistent abundances of the Fe I and Fe II lines. This justifies the Fe I/Fe II ionisation equilibrium method to determine log g for the MW halo giants with unknown distance. The atmospheric parameters of the dSphs and MW stars were checked with independent methods. In the [Fe/H] > - 3.5 regime, the Ti I/Ti II ionisation equilibrium is fulfilled in the NLTE calculations. In the log g - Teff plane, all the stars sit on the giant branch of the evolutionary tracks corresponding to [Fe/H] = - 2 to - 4, in line with their metallicities. For some of the most metal-poor stars of our sample, we achieve relatively inconsistent NLTE abundances from the two ionisation stages for both iron and titanium. We suggest that this is a consequence of the uncertainty in the Teff-colour relation at those metallicities. The results of this work provide the basis for a detailed abundance analysis presented in a companion paper. Tables A.1 and A.2 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A129

Occupational exposures and mammographic density in Spanish women.

PubMed

Lope, Virginia; García-Pérez, Javier; Pérez-Gómez, Beatriz; Pedraza-Flechas, Ana María; Alguacil, Juan; González-Galarzo, Mª Carmen; Alba, Miguel Angel; van der Haar, Rudolf; Cortés-Barragán, Rosa Ana; Pedraz-Pingarrón, Carmen; Moreo, Pilar; Santamariña, Carmen; Ederra, María; Vidal, Carmen; Salas-Trejo, Dolores; Sánchez-Contador, Carmen; Llobet, Rafael; Pollán, Marina

2018-02-01

The association between occupational exposures and mammographic density (MD), a marker of breast cancer risk, has not been previously explored. Our objective was to investigate the influence of occupational exposure to chemical, physical and microbiological agents on MD in adult women. This is a population-based cross-sectional study based on 1476 female workers aged 45-65 years from seven Spanish breast cancer screening programmes. Occupational history was surveyed by trained staff. Exposure to occupational agents was assessed using the Spanish job-exposure matrix MatEmESp. Percentage of MD was measured by two radiologists using a semiautomatic computer tool. The association was estimated using mixed log-linear regression models adjusting for age, education, body mass index, menopausal status, parity, smoking, alcohol intake, type of mammography, family history of breast cancer and hormonal therapy use, and including screening centre and professional reader as random effects terms. Although no association was found with most of the agents, women occupationally exposed to perchloroethylene (e β =1.51; 95% CI 1.04 to 2.19), ionising radiation (e β =1.23; 95% CI 0.99 to 1.52) and mould spores (e β =1.44; 95% CI 1.01 to 2.04) tended to have higher MD. The percentage of density increased 12% for every 5 years exposure to perchloroethylene or mould spores, 11% for every 5 years exposure to aliphatic/alicyclic hydrocarbon solvents and 3% for each 5 years exposure to ionising radiation. Exposure to perchloroethylene, ionising radiation, mould spores or aliphatic/alicyclic hydrocarbon solvents in occupational settings could be associated with higher MD. Further studies are needed to clarify the accuracy and the reasons for these findings. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Looking into individual coffee beans during the roasting process: direct micro-probe sampling on-line photo-ionisation mass spectrometric analysis of coffee roasting gases.

PubMed

Hertz-Schünemann, Romy; Streibel, Thorsten; Ehlert, Sven; Zimmermann, Ralf

2013-09-01

A micro-probe (μ-probe) gas sampling device for on-line analysis of gases evolving in confined, small objects by single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) was developed. The technique is applied for the first time in a feasibility study to record the formation of volatile and flavour compounds during the roasting process within (inside) or in the direct vicinity (outside) of individual coffee beans. A real-time on-line analysis of evolving volatile and semi-volatile organic compounds (VOC and SVOC) as they are formed under the mild pyrolytic conditions of the roasting process was performed. The soft-ionisation mass spectra depict a molecular ion signature, which is well corresponding with the existing knowledge of coffee roasting and evolving compounds. Additionally, thereby it is possible to discriminate between Coffea arabica (Arabica) and Coffea canephora (Robusta). The recognized differences in the roasting gas profiles reflect the differences in the precursor composition of the coffee cultivars very well. Furthermore, a well-known set of marker compounds for Arabica and Robusta, namely the lipids kahweol and cafestol (detected in their dehydrated form at m/z 296 and m/z 298, respectively) were observed. If the variation in time of different compounds is observed, distinctly different evolution behaviours were detected. Here, phenol (m/z 94) and caffeine (m/z 194) are exemplary chosen, whereas phenol shows very sharp emission peaks, caffeine do not have this highly transient behaviour. Finally, the changes of the chemical signature as a function of the roasting time, the influence of sampling position (inside, outside) and cultivar (Arabica, Robusta) is investigated by multivariate statistics (PCA). In summary, this pilot study demonstrates the high potential of the measurement technique to enhance the fundamental knowledge of the formation processes of volatile and semi-volatile flavour compounds inside the individual coffee bean.

Genotoxic effects of high dose rate X-ray and low dose rate gamma radiation in ApcMin/+ mice.

PubMed

Graupner, Anne; Eide, Dag M; Brede, Dag A; Ellender, Michele; Lindbo Hansen, Elisabeth; Oughton, Deborah H; Bouffler, Simon D; Brunborg, Gunnar; Olsen, Ann Karin

2017-10-01

Risk estimates for radiation-induced cancer in humans are based on epidemiological data largely drawn from the Japanese atomic bomb survivor studies, which received an acute high dose rate (HDR) ionising radiation. Limited knowledge exists about the effects of chronic low dose rate (LDR) exposure, particularly with respect to the application of the dose and dose rate effectiveness factor. As part of a study to investigate the development of colon cancer following chronic LDR vs. acute HDR radiation, this study presents the results of genotoxic effects in blood of exposed mice. CBAB6 F1 Apc +/+ (wild type) and Apc Min/+ mice were chronically exposed to estimated whole body absorbed doses of 1.7 or 3.2 Gy 60 Co-γ-rays at a LDR (2.2 mGy h -1 ) or acutely exposed to 2.6 Gy HDR X-rays (1.3 Gy min -1 ). Genotoxic endpoints assessed in blood included chromosomal damage (flow cytometry based micronuclei (MN) assay), mutation analyses (Pig-a gene mutation assay), and levels of DNA lesions (Comet assay, single-strand breaks (ssb), alkali labile sites (als), oxidized DNA bases). Ionising radiation (ca. 3 Gy) induced genotoxic effects dependent on the dose rate. Chromosomal aberrations (MN assay) increased 3- and 10-fold after chronic LDR and acute HDR, respectively. Phenotypic mutation frequencies as well as DNA lesions (ssb/als) were modulated after acute HDR but not after chronic LDR. The Apc Min/+ genotype did not influence the outcome in any of the investigated endpoints. The results herein will add to the scant data available on genotoxic effects following chronic LDR of ionising radiation. Environ. Mol. Mutagen. 58:560-569, 2017. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

Genotoxic effects of high dose rate X‐ray and low dose rate gamma radiation in ApcMin/+ mice

PubMed Central

Eide, Dag M.; Brede, Dag A.; Ellender, Michele; Lindbo Hansen, Elisabeth; Oughton, Deborah H.; Bouffler, Simon D.; Brunborg, Gunnar; Olsen, Ann Karin

2017-01-01

Risk estimates for radiation‐induced cancer in humans are based on epidemiological data largely drawn from the Japanese atomic bomb survivor studies, which received an acute high dose rate (HDR) ionising radiation. Limited knowledge exists about the effects of chronic low dose rate (LDR) exposure, particularly with respect to the application of the dose and dose rate effectiveness factor. As part of a study to investigate the development of colon cancer following chronic LDR vs. acute HDR radiation, this study presents the results of genotoxic effects in blood of exposed mice. CBAB6 F1 Apc+/+ (wild type) and ApcMin/+ mice were chronically exposed to estimated whole body absorbed doses of 1.7 or 3.2 Gy 60Co‐γ‐rays at a LDR (2.2 mGy h−1) or acutely exposed to 2.6 Gy HDR X‐rays (1.3 Gy min−1). Genotoxic endpoints assessed in blood included chromosomal damage (flow cytometry based micronuclei (MN) assay), mutation analyses (Pig‐a gene mutation assay), and levels of DNA lesions (Comet assay, single‐strand breaks (ssb), alkali labile sites (als), oxidized DNA bases). Ionising radiation (ca. 3 Gy) induced genotoxic effects dependent on the dose rate. Chromosomal aberrations (MN assay) increased 3‐ and 10‐fold after chronic LDR and acute HDR, respectively. Phenotypic mutation frequencies as well as DNA lesions (ssb/als) were modulated after acute HDR but not after chronic LDR. The ApcMin/+ genotype did not influence the outcome in any of the investigated endpoints. The results herein will add to the scant data available on genotoxic effects following chronic LDR of ionising radiation. Environ. Mol. Mutagen. 58:560–569, 2017. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society PMID:28856770

HYDRO2GEN: Non-thermal hydrogen Balmer and Paschen emission in solar flares generated by electron beams

NASA Astrophysics Data System (ADS)

Druett, M. K.; Zharkova, V. V.

2018-03-01

Aim. Sharp rises of hard X-ray (HXR) emission accompanied by Hα line profiles with strong red-shifts up to 4 Å from the central wavelength, often observed at the onset of flares with the Specola Solare Ticinese Telescope (STT) and the Swedish Solar Telescope (SST), are not fully explained by existing radiative models. Moreover, observations of white light (WL) and Balmer continuum emission with the Interface Region Imaging Spectrograph (IRISH) reveal strong co-temporal enhancements and are often nearly co-spatial with HXR emission. These effects indicate a fast effective source of excitation and ionisation of hydrogen atoms in flaring atmospheres associated with HXR emission. In this paper, we investigate electron beams as the agents accounting for the observed hydrogen line and continuum emission. Methods: Flaring atmospheres are considered to be produced by a 1D hydrodynamic response to the injection of an electron beam defining their kinetic temperatures, densities, and macro velocities. We simulated a radiative response in these atmospheres using a fully non-local thermodynamic equilibrium (NLTE) approach for a 5-level plus continuum hydrogen atom model, considering its excitation and ionisation by spontaneous, external, and internal diffusive radiation and by inelastic collisions with thermal and beam electrons. Simultaneous steady-state and integral radiative transfer equations in all optically thick transitions (Lyman and Balmer series) were solved iteratively for all the transitions to define their source functions with the relative accuracy of 10-5. The solutions of the radiative transfer equations were found using the L2 approximation. Resulting intensities of hydrogen line and continuum emission were also calculated for Balmer and Paschen series. Results: We find that inelastic collisions with beam electrons strongly increase excitation and ionisation of hydrogen atoms from the chromosphere to photosphere. This leads to an increase in Lyman continuum radiation, which has high optical thickness, and after the beam is off it governs hydrogen ionisation and leads to the long lasting orders of magnitude enhancement of emission in Balmer and Paschen continua. The ratio of Balmer-to-other-continuum head intensities are found to be correlated with the initial flux of the beam. The height distribution of contribution functions for Paschen continuum emission indicate a close correlation with the observations of heights of WL and HXR emission reported for limb flares. This process also leads to a strong increase of wing emission (Stark's wings) in Balmer and Paschen lines, which is superimposed on large red-shifted enhancements of Hα-Hγ line emission resulting from a downward motion by hydrodynamic shocks. The simulated line profiles are shown to fit closely the observations for various flaring events.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spagliardi, Fabio

Liquid argon Time Projection Chambers (LArTPCs) are becoming widely used as neutrino detectors because of their image-like event reconstruction which enables precision neutrino measurements. They primarily use ionisation charge to reconstruct neutrino events. It has been shown, however, that the scintillation light emitted by liquid argon could be exploited to improve their performance. As the neutrino measurements planned in the near future require large-scale experiments, their construction presents challenges in terms of both charge and light collection. In this dissertation we present solutions developed to improve the performance in both aspects of these detectors. We present a new wire tensioningmore » measurement method that allows a remote measurement of the tension of the large number wires that constitute the TPC anode. We also discuss the development and installation of WLS-compound covered foils for the SBND neutrino detector at Fermilab, which is a technique proposed t o augment light collection in LArTPCs. This included preparing a SBND-like mesh cathode and testing it in the Run III of LArIAT, a test beam detector also located at Fermilab. Finally, we present a study aimed at understanding late scintillation light emitted by recombining positive argon ions using LArIAT data, which could affect large scale surface detectors.« less

Radiogenic Isotopes As Paleoceanographic Tracers in Deep-Sea Corals: Advances in TIMS Measurements of Pb Isotopes and Application to Southern Ocean Corals

NASA Astrophysics Data System (ADS)

Wilson, D. J.; van de Flierdt, T.; Bridgestock, L. J.; Paul, M.; Rehkamper, M.; Robinson, L. F.; Adkins, J. F.

2014-12-01

Deep-sea corals have emerged as a valuable archive of deep ocean paleoceanographic change, with uranium-series dating providing absolute ages and the potential for centennial resolution. In combination with measurements of radiocarbon, neodymium isotopes and clumped isotopes, this archive has recently been exploited to reconstruct changes in ventilation, water mass sourcing and temperature in relation to millennial climate change. Lead (Pb) isotopes in both corals and seawater have also been used to track anthropogenic inputs through space and time and to trace transport pathways within the oceans. Better understanding of the oceanic Pb cycle is emerging from the GEOTRACES programme. However, while Pb isotopes have been widely used in environmental studies, their full potential as a (pre-anthropogenic) paleoceanographic tracer remains to be exploited. In deep-sea corals, challenges exist from low Pb concentrations in aragonite in comparison to secondary coatings, the potential for contamination, and the efficient elemental separation required for measurement by thermal ionisation mass spectrometry (TIMS). Here we discuss progress in measuring Pb isotopes in coral aragonite using a 207Pb-204Pb double spike on a ThermoFinnigan Triton TIMS. For a 2 ng NIST-981 Pb standard, the long term reproducibility (using 1011 Ω resistors) is ~1000 ppm (2 s.d.) on 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios. We now show that using a new 1012 Ω resistor to measure the small 204Pb beam improves the internal precision on these ratios from ~500 ppm (2 s.e.) to ~250 ppm (2 s.e.) and we envisage a potential improvement in the long term reproducibility as a consequence. We further assess the internal precision and external reproducibility of our method using a BCR-2 rock standard and an in-house coral standard. Preliminary evidence on the application of this method to natural samples is derived from cleaning experiments and replication tests on deep-sea corals from the Southern Ocean.

Vaporisation of a dicationic ionic liquid.

PubMed

Lovelock, Kevin R J; Deyko, Alexey; Corfield, Jo-Anne; Gooden, Peter N; Licence, Peter; Jones, Robert G

2009-02-02

Highest heat of vaporization yet: The dicationic ionic liquid [C(3)(C(1)Im)(2)][Tf(2)N](2) evaporates as a neutral ion triplet. These neutral ion triplets can then be ionised to form singly and doubly charged ions. The mass spectrum exhibits the dication attached to one remaining anion, and the naked dication itself (see picture).

Pre-Service Teachers' Subject Knowledge of and Attitudes about Radioactivity and Ionising Radiation

ERIC Educational Resources Information Center

Colclough, Nicholas Denys; Lock, Roger; Soares, Allan

2011-01-01

This study focussed on secondary school (11-18 years) pre-service teachers' (n = 73) knowledge of and attitudes towards risks associated with alpha, beta, and gamma radiations. A multi-method approach was used with physics, chemistry, biology, and history graduates undertaking the one-year initial teacher training, Post Graduate Certificate in…

UK guidance on the management of personal dosimetry systems for healthcare staff working at multiple organizations.

PubMed

Rogers, Andy; Chapple, Claire-Louise; Murray, Maria; Platton, David; Saunderson, John

2017-11-01

There has been concern expressed by the UK regulator, the Health & Safety Executive, regarding the management of occupation dose for healthcare radiation workers who work across multiple organizations. In response to this concern, the British Institute of Radiology led a working group of relevant professional bodies to develop guidance in this area. The guidance addresses issues of general system management that would apply to all personal dosimetry systems, regardless of whether or not the workers within that system work across organizational boundaries, along with exploring efficient strategies to comply with legislation where those workers do indeed work across organizational boundaries. For those specific instances, the guidance discusses both system requirements to enable organizations to co-operate (Ionising Radiation Regulations 1999 Regulation 15), as well as specific instances of staff exposure. This is broken down into three categories-low, medium and high risk. A suggested approach to each is given to guide employers and their radiation advisers in adopting sensible strategies for the monitoring of their staff and the subsequent sharing of dosimetry data to ensure overall compliance with both dose limits and optimization requirements.

Identification of proteinaceous binders used in artworks by MALDI-TOF mass spectrometry.

PubMed

Kuckova, Stepanka; Hynek, Radovan; Kodicek, Milan

2007-05-01

Proper identification of proteinaceous binders in artworks is essential for specification of the painting technique and thus also for selection of the restoration method; moreover, it might be helpful for the authentication of the artwork. This paper is concerned with the optimisation of analysis of the proteinaceous binders contained in the colour layers of artworks. Within this study, we worked out a method for the preparation and analysis of solid samples from artworks using tryptic cleavage and subsequent analysis of the acquired peptide mixture by matrix-assisted laser desorption/ionisation time of flight mass spectrometry. To make this approach rational and efficient, we created a database of commonly used binders (egg yolk, egg white, casein, milk, curd, whey, gelatine, and various types of animal glues); certain peaks in the mass spectra of these binders, formed by rich protein mixtures, were matched to amino acid sequences of the individual proteins that were found in the Internet database ExPASy; their cleavage was simulated by the program Mass-2.0-alpha4. The method developed was tested on model samples of ground layers prepared by an independent laboratory and then successfully applied to a real sample originating from a painting by Edvard Munch.

Automatic poisson peak harvesting for high throughput protein identification.

PubMed

Breen, E J; Hopwood, F G; Williams, K L; Wilkins, M R

2000-06-01

High throughput identification of proteins by peptide mass fingerprinting requires an efficient means of picking peaks from mass spectra. Here, we report the development of a peak harvester to automatically pick monoisotopic peaks from spectra generated on matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) mass spectrometers. The peak harvester uses advanced mathematical morphology and watershed algorithms to first process spectra to stick representations. Subsequently, Poisson modelling is applied to determine which peak in an isotopically resolved group represents the monoisotopic mass of a peptide. We illustrate the features of the peak harvester with mass spectra of standard peptides, digests of gel-separated bovine serum albumin, and with Escherictia coli proteins prepared by two-dimensional polyacrylamide gel electrophoresis. In all cases, the peak harvester proved effective in its ability to pick similar monoisotopic peaks as an experienced human operator, and also proved effective in the identification of monoisotopic masses in cases where isotopic distributions of peptides were overlapping. The peak harvester can be operated in an interactive mode, or can be completely automated and linked through to peptide mass fingerprinting protein identification tools to achieve high throughput automated protein identification.

LIAD-fs scheme for studies of ultrafast laser interactions with gas phase biomolecules.

PubMed

Calvert, C R; Belshaw, L; Duffy, M J; Kelly, O; King, R B; Smyth, A G; Kelly, T J; Costello, J T; Timson, D J; Bryan, W A; Kierspel, T; Rice, P; Turcu, I C E; Cacho, C M; Springate, E; Williams, I D; Greenwood, J B

2012-05-14

Laser induced acoustic desorption (LIAD) has been used for the first time to study the parent ion production and fragmentation mechanisms of a biological molecule in an intense femtosecond (fs) laser field. The photoacoustic shock wave generated in the analyte substrate (thin Ta foil) has been simulated using the hydrodynamic HYADES code, and the full LIAD process has been experimentally characterised as a function of the desorption UV-laser pulse parameters. Observed neutral plumes of densities >10(9) cm(-3) which are free from solvent or matrix contamination demonstrate the suitability and potential of the source for studying ultrafast dynamics in the gas phase using fs laser pulses. Results obtained with phenylalanine show that through manipulation of fundamental femtosecond laser parameters (such as pulse length, intensity and wavelength), energy deposition within the molecule can be controlled to allow enhancement of parent ion production or generation of characteristic fragmentation patterns. In particular by reducing the pulse length to a timescale equivalent to the fastest vibrational periods in the molecule, we demonstrate how fragmentation of the molecule can be minimised whilst maintaining a high ionisation efficiency. This journal is © the Owner Societies 2012

Laser ablation synthesis of arsenic-phosphide Asm Pn clusters from As-P mixtures. Laser desorption ionisation with quadrupole ion trap time-of-flight mass spectrometry: The mass spectrometer as a synthesizer.

PubMed

Kubáček, Pavel; Prokeš, Lubomír; Pamreddy, Annapurna; Peña-Méndez, Eladia María; Conde, José Elias; Alberti, Milan; Havel, Josef

2018-05-30

Only a few arsenic phosphides are known. A high potential for the generation of new compounds is offered by Laser Ablation Synthesis (LAS) and when Laser Desorption Ionization (LDI) is coupled with simultaneous Time-Of-Flight Mass Spectrometry (TOFMS), immediate identification of the clusters can be achieved. LAS was used for the generation of arsenic phosphides via laser ablation of phosphorus-arsenic mixtures while quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to acquire the mass spectra. Many new As m P n ± clusters (479 binary and 369 mono-elemental) not yet described in the literature were generated in the gas phase and their stoichiometry determined. The likely structures for some of the observed clusters arbitrary selected (20) were computed by density functional theory (DFT) optimization. LAS is an advantageous approach for the generation of new As m P n clusters, while mass spectrometry was found to be an efficient technique for the determination of cluster stoichiometry. The results achieved might inspire the synthesis of new materials. Copyright © 2018 John Wiley & Sons, Ltd.

Quantum chemical study on the NLO and NBO properties of 4-hydroxy quinoline-2-carboxylic acid

NASA Astrophysics Data System (ADS)

Pattanayak, Subrat Kumar

2018-05-01

The nonlinear optical properties and natural bond analysis properties, different global chemical reactivity properties of the compound 4-hydroxy quinoline-2-carboxylic acid are studied by density function theory. The dipole moment (μ) and linear polarizability are found 1.60259 D and 15.138×10-24esu respectively. A comparatively greater value dipole moment 1.46154 D is obtained in direction of μy. It was observed the interaction energies of acceptor of NBO C1 - C2 and donor C5 - C6, NBO of C13 - N15 and C9 - C12, NBO of C13 - N15 and C18 - O21, NBO of O19 and C18 - O21 are 30.92, 358.86, 320.39, 58.55 Kcal/mol. We are getting the low ionization energy 7.033 electron volt (eV) for the studied molecule, which indicates the high inhibition efficiency. Here we note that, high value of ionisation energy indicating the high stability as well as inertness of that molecule. The HOMO and LUMO energies are found -7.033 eV and -2.5212 eV respectively.

An efficient basis set representation for calculating electrons in molecules

DOE PAGES

Jones, Jeremiah R.; Rouet, Francois -Henry; Lawler, Keith V.; ...

2016-04-27

The method of McCurdy, Baertschy, and Rescigno, is generalised to obtain a straightforward, surprisingly accurate, and scalable numerical representation for calculating the electronic wave functions of molecules. It uses a basis set of product sinc functions arrayed on a Cartesian grid, and yields 1 kcal/mol precision for valence transition energies with a grid resolution of approximately 0.1 bohr. The Coulomb matrix elements are replaced with matrix elements obtained from the kinetic energy operator. A resolution-of-the-identity approximation renders the primitive one- and two-electron matrix elements diagonal; in other words, the Coulomb operator is local with respect to the grid indices. Themore » calculation of contracted two-electron matrix elements among orbitals requires only O( Nlog (N)) multiplication operations, not O( N 4), where N is the number of basis functions; N = n 3 on cubic grids. The representation not only is numerically expedient, but also produces energies and properties superior to those calculated variationally. Absolute energies, absorption cross sections, transition energies, and ionisation potentials are reported for 1- (He +, H + 2), 2- (H 2, He), 10- (CH 4), and 56-electron (C 8H 8) systems.« less

Rapid characterisation of Klebsiella oxytoca isolates from contaminated liquid hand soap using mass spectrometry, FTIR and Raman spectroscopy.

PubMed

Dieckmann, Ralf; Hammerl, Jens Andre; Hahmann, Hartmut; Wicke, Amal; Kleta, Sylvia; Dabrowski, Piotr Wojciech; Nitsche, Andreas; Stämmler, Maren; Al Dahouk, Sascha; Lasch, Peter

2016-06-23

Microbiological monitoring of consumer products and the efficiency of early warning systems and outbreak investigations depend on the rapid identification and strain characterisation of pathogens posing risks to the health and safety of consumers. This study evaluates the potential of three rapid analytical techniques for identification and subtyping of bacterial isolates obtained from a liquid hand soap product, which has been recalled and reported through the EU RAPEX system due to its severe bacterial contamination. Ten isolates recovered from two bottles of the product were identified as Klebsiella oxytoca and subtyped using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI TOF MS), near-infrared Fourier transform (NIR FT) Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Comparison of the classification results obtained by these phenotype-based techniques with outcomes of the DNA-based methods pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST) and single nucleotide polymorphism (SNP) analysis of whole-genome sequencing (WGS) data revealed a high level of concordance. In conclusion, a set of analytical techniques might be useful for rapid, reliable and cost-effective microbial typing to ensure safe consumer products and allow source tracking.

Improved measurement of protein synthesis in human subjects using 2H-phenylalanine isotopomers and gas chromatography/mass spectrometry.

PubMed

Preston, Tom; Small, Alexandra C

2010-03-15

Sensitive methods to measure protein synthetic rate in vivo are required to assess changes in protein expression, especially when comparing healthy with infirm subjects. We have previously applied a 'flooding dose' procedure using (2)H(5)-phenylalanine ((2)H(5)-phe) and (2)H(8)-phe isotopomers as tracers, which has proven successful in measuring albumin and fibrinogen synthesis in response to feeding in cancer patients. Using tert-butyldimethylsilyl derivatives, we have observed that (2)H(7)-phe is formed with time in vivo from (2)H(8)-phe, probably during transamination. This increases errors when estimating the fractional synthetic rate (FSR) using the (2)H(8)-phe isotopomer compared with the (2)H(5)-phe isotopomer. We sought to improve this situation by use of an alternative derivative that overcomes this problem whilst also streamlining sample preparation. When using N-ethoxycarbonyltrifluoroethyl (ECTFE) amino acid esters, (2)H(8)-phe is effectively converted into (2)H(7)-phe through fragmentation under electron ionisation (EI), allowing both (2)H(8)-phe and (2)H(7)-phe isotopomers to be measured as a single intense C(7)(2)H(7)(+) fragment at 98 Th. To illustrate the improved situation, the mean RMS residual was calculated for all albumin data, for each isotopomer and for each derivative. Albumin-bound Phe was analysed as ECTFE-phe with improved precision, independent of the isotopomer used, confirming that the new derivative is superior. Copyright 2010 John Wiley & Sons, Ltd.

[The concept of nuclear physics].

PubMed

Ducassou, D

1995-03-15

Understanding of the biological effects of radioactivity on living matter requires some basic notions of nuclear physics. The interreactions between living matter and ionising rays, emitted by natural or artificial radioelements, are responsible for such effects. These radioelements are characterised by the period, the nature and the energy of the rays they emit; they constitute the source of radiation whose effects generally depend on their activity.

The Square Kilometre Array Epoch of Reionisation and Cosmic Dawn Experiment

NASA Astrophysics Data System (ADS)

Trott, Cathryn M.

2018-05-01

The Square Kilometre Array (SKA) Epoch of Reionisation and Cosmic Dawn (EoR/CD) experiments aim to explore the growth of structure and production of ionising radiation in the first billion years of the Universe. Here I describe the experiments planned for the future low-frequency components of the Observatory, and work underway to define, design and execute these programs.

Calcium-phosphate metabolism in patients with multiple sclerosis.

PubMed

Kubicka-Baczyk, K; Labuz-Roszak, B; Pierzchala, K; Adamczyk-Sowa, M; Machowska-Majchrzak, A

2015-06-01

The purpose of this study was to evaluate the concentration of 25-hydroxycholecalciferol and parameters of calcium-phosphate metabolism at different periods of relapsing-remitting multiple sclerosis (RRMS). Forty-five patients, residents of Poland (49°-50°, N), were enrolled in the study, i.e. 15 immediately after the diagnosis of RRMS, 15 at the early stage and 15 at the advanced stage of RRMS. The results were compared to values obtained in 20 age- and sex-matched controls. Lower serum concentrations of 25-hydroxycholecalciferol and ionised calcium were found in patients compared to the control group. In patients with the disease duration of 5-6 years, concentrations of 25-hydroxycholecalciferol and ionised calcium were lower than in patients in the earlier period of RRMS. The inverse and clearer direction of changes was found in parathormone serum concentration in patients compared to the controls. In patients with a longer disease duration, a significantly lower 25-hydroxycholecalciferol concentration was found in female patients compared to male patients. In patients, more frequent 25-hydroxycholecalciferol and unsaturated fatty acids' supplementation was observed compared to the controls. In RRMS patients, calcium-phosphate metabolism is disturbed which increases during disease progression.

Characterization of cis- and trans-octadecenoic acid positional isomers in edible fat and oil using gas chromatography-flame ionisation detector equipped with highly polar ionic liquid capillary column.

PubMed

Yoshinaga, Kazuaki; Asanuma, Masaharu; Mizobe, Hoyo; Kojima, Koichi; Nagai, Toshiharu; Beppu, Fumiaki; Gotoh, Naohiro

2014-10-01

In this study, the characterisation of all cis- and trans-octadecenoic acid (C18:1) positional isomers in partially hydrogenated vegetable oil (PHVO) and milk fat, which contain several cis- and trans-C18:1 positional isomers, was achieved by gas chromatography-flame ionisation detector equipped with a highly polar ionic liquid capillary column (SLB-IL111). Prior to analysis, the cis- and trans-C18:1 fractions in PHVO and milk fat were separated using a silver-ion cartridge. The resolution of all cis-C18:1 positional isomers was successfully accomplished at the optimal isothermal column temperature of 120 °C. Similarly, the positional isomers of trans-C18:1, except for trans-6-C18:1 and trans-7-C18:1, were separated at 120 °C. The resolution of trans-6-C18:1 and trans-7-C18:1 isomers was made possible by increasing the column temperature to 160 °C. This analytical method is suitable for determining the cis- and trans-C18:1 positional isomers in edible fats and oils. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparative evaluation of matrix-assisted laser desorption ionisation-time of flight mass spectrometry and conventional phenotypic-based methods for identification of clinically important yeasts in a UK-based medical microbiology laboratory.

PubMed

Fatania, Nita; Fraser, Mark; Savage, Mike; Hart, Jason; Abdolrasouli, Alireza

2015-12-01

Performance of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) was compared in a side-by side-analysis with conventional phenotypic methods currently in use in our laboratory for identification of yeasts in a routine diagnostic setting. A diverse collection of 200 clinically important yeasts (19 species, five genera) were identified by both methods using standard protocols. Discordant or unreliable identifications were resolved by sequencing of the internal transcribed spacer region of the rRNA gene. MALDI-TOF and conventional methods were in agreement for 182 isolates (91%) with correct identification to species level. Eighteen discordant results (9%) were due to rarely encountered species, hence the difficulty in their identification using traditional phenotypic methods. MALDI-TOF MS enabled rapid, reliable and accurate identification of clinically important yeasts in a routine diagnostic microbiology laboratory. Isolates with rare, unusual or low probability identifications should be confirmed using robust molecular methods. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Synthetic diamond devices for radio-oncology applications

NASA Astrophysics Data System (ADS)

Descamps, C.; Tromson, D.; Mer, C.; Nesládek, M.; Bergonzo, P.; Benabdesselam, M.

2006-09-01

Diamond exhibits a range of outstanding properties that make it a material of interest for radiation detection and particularly in the field of dosimetry applications. In fact, its crystallographic structure makes it chemically inert and radiation hard. Moreover, its atomic number (carbon Z = 6) close to the equivalent effective atomic number of human soft tissues (Z = 7.4) and of water (reference material in radiotherapy) enables a direct evaluation of the deposited dose without requiring corrections for material nature or energy. Finally, as a bio-compatible material, it can be sterilised, and it is non-toxic thus giving strong advantages for medical uses. Natural diamonds are expensive, rare and their use implies a severe gem selection to fabricate reproducible and reliable devices. The emergence of synthetic samples from the chemical vapour deposition (CVD) technique offers new possibilities in the fabrication of ionisation chamber for the particular field of radiotherapy. Previous studies have shown that defect levels present in material clearly influence the device response under irradiation. Therefore, in order to optimise dosimetric characteristics needed in radiotherapy applications, various low and precisely nitrogen concentrations were incorporated in the material during growth. Influence of these incorporations on ionisation chamber response under medical cobalt irradiator is presented in this paper.

Ethical foundations of environmental radiological protection.

PubMed

Oughton, D H

2016-06-01

Assessing the potential ecological impact of ionising radiation raises a number of ethical questions. These include fundamental questions such as what exactly constitutes harming the environment, and how the environment should be valued, as well as links to political protection principles such as sustainability and biodiversity. Starting from developments within ecological risk assessment, this paper summarises some of the ethical issues concerning the protection of the environment from radiation. Chapter 2 gives a brief overview of different philosophical and cultural world views on valuing the environment in a context of radiation risk. Chapter 3 addresses some recent challenges to proposed environmental protection frameworks, including practical applications following the Chernobyl and Fukushima accidents, and some scientific developments such as the ecosystem approach. Finally, Chapter 4 offers some recommendations on how ethical evaluation can help produce a more robust and transparent approach to the protection of the environment. In conclusion, there is a need for a holistic evaluation of the environmental impacts of ionising radiation that not only considers the direct consequences on the health of humans and non-human species, but also the more complex social, ethical, and economic consequences of both human and non-human exposures. © The International Society for Prosthetics and Orthotics.

Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Woulfe, P.; Sullivan, F. J.; O'Keeffe, S.

2016-05-01

An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is presented, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 250μm of a 500μm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for brachytherapy, in prostate cancer treatment, providing oncologists with real-time information of the radiation dose to the target area and/or nearby critical structures. The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to Iodine-125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

Modeling of plasma distortions by laser-induced ablation spectroscopy (LIAS) and implications for the interpretation of LIAS measurements

NASA Astrophysics Data System (ADS)

Tokar, M. Z.; Gierse, N.; Philipps, V.; Samm, U.

2015-09-01

For the interpretation of the line radiation observed from laser induced ablation spectroscopy (LIAS) such parameters as the density and temperature of electrons within very compact clouds of atoms and singly charged ions of ablated material have to be known. Compared to the local plasma conditions prior to the laser pulse, these can be strongly changed during LIAS since new electrons are generated by the ionisation of particles ejected from the irradiated target. Because of their transience and spatial inhomogeneity it is technically difficult to measure disturbances induced in the plasma by LIAS. To overcome this uncertainty a numerical model has been elaborated, providing a self-consistent description for the spreading of ablated particles and accompanying modifications in the plasma. The results of calculations for LIAS performed on carbon-containing targets in Ohmic and additionally heated discharges in the tokamak TEXTOR are presented. Due to the increase in the electron density the ‘ionisation per photon’ ratio, S/XB factor, is significantly enhanced compared to unperturbed plasma conditions. The impact of the amount of material ablated and of the plasma conditions before LIAS on the level of the S/XB-enhancement is investigated.

Characterisation of chemical components for identifying historical Chinese textile dyes by ultra high performance liquid chromatography - photodiode array - electrospray ionisation mass spectrometer.

PubMed

Han, Jing; Wanrooij, Jantien; van Bommel, Maarten; Quye, Anita

2017-01-06

This research makes the first attempt to apply Ultra High Performance Liquid Chromatography (UHPLC) coupled to both Photodiode Array detection (PDA) and Electrospray Ionisation Mass Spectrometer (ESI-MS) to the chemical characterisation of common textile dyes in ancient China. Three different extraction methods, respectively involving dimethyl sulfoxide (DMSO)-oxalic acid, DMSO and hydrochloric acid, are unprecedentedly applied together to achieve an in-depth understanding of the chemical composition of these dyes. The first LC-PDA-MS database of the chemical composition of common dyes in ancient China has been established. The phenomena of esterification and isomerisation of the dye constituents of gallnut, gardenia and saffron, and the dye composition of acorn cup dyed silk are clarified for the first time. 6-Hydroxyrubiadin and its glycosides are first reported on a dyed sample with Rubia cordifolia from China. UHPLC-PDA-ESI-MS with a C18 BEH shield column shows significant advantages in the separation and identification of similar dye constituents, particularly in the cases of analysing pagoda bud and turmeric dyed sample extracts. Copyright © 2016 Elsevier B.V. All rights reserved.

Resolving the Large Scale Spectral Variability of the Luminous Seyfert 1 Galaxy 1H 0419-577: Evidence for a New Emission Component and Absorption by Cold Dense Matter

NASA Technical Reports Server (NTRS)

Pounds, K. A.; Reeves, J. N.; Page, K. L.; OBrien, P. T.

2004-01-01

An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 in September 2002, when the source was in an extreme low-flux state, found a very hard X-ray spectrum at 1-10 keV with a strong soft excess below -1 keV. Comparison with an earlier XMM-Newton observation when 1H 0419-577 was X-ray bright indicated the dominant spectral variability was due to a steep power law or cool Comptonised thermal emission. Four further XMM-Newton observations, with 1H 0419-577 in intermediate flux states, now support that conclusion, while we also find the variable emission component in intermediate state difference spectra to be strongly modified by absorption in low ionisation matter. The variable soft excess then appears to be an artefact of absorption of the underlying continuum while the core soft emission can be attributed to re- combination in an extended region of more highly ionised gas. We note the wider implications of finding substantial cold dense matter overlying (or embedded in) the X-ray continuum source in a luminous Seyfert 1 galaxy.

C-glucosidic ellagitannins from Lythri herba (European Pharmacopoeia): chromatographic profile and structure determination.

PubMed

Piwowarski, Jakub P; Kiss, Anna K

2013-01-01

Lythri herba, a pharmacopoeial plant material (European Pharmacopoea), is obtained from flowering parts of purple loosestrife (Lythrum salicaria L.). Although extracts from this plant material have been proven to possess some interesting biological activities and its pharmacopoeial standardisation is based on total tannin content determination, the phytochemical characterisation of this main group of compounds has not yet been fully conducted. To isolate ellagitannins from Lythri herba, determine their structures and develop chromatographic methods for their qualitative analysis. Five C-glucosidic ellagitannins - monomeric- vescalagin and castalagin together with new dimeric structures - salicarinins A-C, composed of vescalagin and stachyurin, vescalagin and casuarinin, castalagin and casuarinin units connected via formation of valoneoyl group, were isolated using column chromatography and preparative HPLC. Structures were determined according to (1) H and (13) C-NMR (one- and two-dimensional), electrospray ionisation-time of flight (ESI-TOF), electrospray ionisation-ion trap (ESI-MS(n) ) and circular dichroism (CD) spectra, together with acidic hydrolysis products analysis. HPTLC on RP-18 modified plates and HPLC-DAD-MS(n) on RP-18 column methods were developed for separation of the five main ellagitannins. Copyright © 2012 John Wiley & Sons, Ltd.

Surface Acoustic Wave Nebulisation Mass Spectrometry for the Fast and Highly Sensitive Characterisation of Synthetic Dyes in Textile Samples

NASA Astrophysics Data System (ADS)

Astefanei, Alina; van Bommel, Maarten; Corthals, Garry L.

2017-10-01

Surface acoustic wave nebulisation (SAWN) mass spectrometry (MS) is a method to generate gaseous ions compatible with direct MS of minute samples at femtomole sensitivity. To perform SAWN, acoustic waves are propagated through a LiNbO3 sampling chip, and are conducted to the liquid sample, which ultimately leads to the generation of a fine mist containing droplets of nanometre to micrometre diameter. Through fission and evaporation, the droplets undergo a phase change from liquid to gaseous analyte ions in a non-destructive manner. We have developed SAWN technology for the characterisation of organic colourants in textiles. It generates electrospray-ionisation-like ions in a non-destructive manner during ionisation, as can be observed by the unmodified chemical structure. The sample size is decreased by tenfold to 1000-fold when compared with currently used liquid chromatography-MS methods, with equal or better sensitivity. This work underscores SAWN-MS as an ideal tool for molecular analysis of art objects as it is non-destructive, is rapid, involves minimally invasive sampling and is more sensitive than current MS-based methods. [Figure not available: see fulltext.

Model simulations of the impact of energetic particle precipitation onto the upper and middle atmosphere

NASA Astrophysics Data System (ADS)

Wieters, Nadine; Sinnhuber, Miriam; Winkler, Holger; Berger, Uwe; Maik Wissing, Jan; Stiller, Gabriele; Funke, Bernd; Notholt, Justus

Solar eruptions and geomagnetic storms can produce fluxes of high-energy protons and elec-trons, so-called Solar Energetic Particle Events, which can enter the Earth's atmosphere espe-cially in polar regions. These particle fluxes primarily cause ionisation and excitation in the upper atmosphere, and thereby the production of HOx and NOx species, which are catalysts for the reduction of ozone. To simulate such particle events, ionisation rates, calculated by the Atmospheric Ionization Module Osnabrück AIMOS (University of Osnabrück), have been implemented into the Bremen 3D Chemistry and Transport Model. To cover altitudes up to the mesopause, the model is driven by meteorological data, provided by the Leibniz-Institute Middle Atmosphere Model LIMA (IAP Kühlungsborn). For several electron and proton events during the highly solar-active period 2003/2004, model calculations have been carried out. To investigate the accordance of modeled to observed changes for atmospheric constituents like NO, NO2 , HNO3 , N2 O5 , ClO, and O3 , results of these calculations will be compared to measurements by the Michelson Interferometer for Passive Atmospheric Sounding MIPAS (ENVISAT) instrument. Computed model results and comparisons with measurements will be presented.

Covariance mapping techniques

NASA Astrophysics Data System (ADS)

Frasinski, Leszek J.

2016-08-01

Recent technological advances in the generation of intense femtosecond pulses have made covariance mapping an attractive analytical technique. The laser pulses available are so intense that often thousands of ionisation and Coulomb explosion events will occur within each pulse. To understand the physics of these processes the photoelectrons and photoions need to be correlated, and covariance mapping is well suited for operating at the high counting rates of these laser sources. Partial covariance is particularly useful in experiments with x-ray free electron lasers, because it is capable of suppressing pulse fluctuation effects. A variety of covariance mapping methods is described: simple, partial (single- and multi-parameter), sliced, contingent and multi-dimensional. The relationship to coincidence techniques is discussed. Covariance mapping has been used in many areas of science and technology: inner-shell excitation and Auger decay, multiphoton and multielectron ionisation, time-of-flight and angle-resolved spectrometry, infrared spectroscopy, nuclear magnetic resonance imaging, stimulated Raman scattering, directional gamma ray sensing, welding diagnostics and brain connectivity studies (connectomics). This review gives practical advice for implementing the technique and interpreting the results, including its limitations and instrumental constraints. It also summarises recent theoretical studies, highlights unsolved problems and outlines a personal view on the most promising research directions.

Assessment of radiation protection practices among radiographers in Lagos, Nigeria.

PubMed

Eze, Cletus Uche; Abonyi, Livinus Chibuzo; Njoku, Jerome; Irurhe, Nicholas Kayode; Olowu, Oluwabola

2013-11-01

Use of ionising radiation in diagnostic radiography could lead to hazards such as somatic and genetic damages. Compliance to safe work and radiation protection practices could mitigate such risks. The aim of the study was to assess the knowledge and radiation protection practices among radiographers in Lagos, Nigeria. The study was a prospective cross sectional survey. Convenience sampling technique was used to select four x-ray diagnostic centres in four tertiary hospitals in Lagos metropolis. Data were analysed with Epi- info software, version 3.5.1. Average score on assessment of knowledge was 73%. Most modern radiation protection instruments were lacking in all the centres studied. Application of shielding devices such as gonad shield for protection was neglected mostly in government hospitals. Most x-ray machines were quite old and evidence of quality assurance tests performed on such machines were lacking. Radiographers within Lagos metropolis showed an excellent knowledge of radiation protection within the study period. Adherence to radiation protection practices among radiographers in Lagos metropolis during the period studied was, however, poor. Radiographers in Lagos, Nigeria should embrace current trends in radiation protection and make more concerted efforts to apply their knowledge in protecting themselves and patients from harmful effects of ionising radiation.

Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Woulfe, P.; O'Keeffe, S.; Sullivan, F. J.

2018-02-01

An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is developed, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 700μm of a 1mm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for low dose rate (LDR) brachytherapy, in prostate cancer treatment, providing radiation oncologists with real-time information of the radiation dose to the target area and/or nearby organs at risk (OARs). The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to 0.397mCi of Iodine125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

Quantitative analysis of major dibenzocyclooctane lignans in Schisandrae fructus by online TLC-DART-MS.

PubMed

Kim, Hye Jin; Oh, Myung Sook; Hong, Jongki; Jang, Young Pyo

2011-01-01

Direct analysis in real time (DART) ion source is a powerful ionising technique for the quick and easy detection of various organic molecules without any sample preparation steps, but the lack of quantitation capacity limits its extensive use in the field of phytochemical analysis. To improvise a new system which utilize DART-MS as a hyphenated detector for quantitation. A total extract of Schisandra chinensis fruit was analyzed on a TLC plate and three major lignan compounds were quantitated by three different methods of UV densitometry, TLC-DART-MS and HPLC-UV to compare the efficiency of each method. To introduce the TLC plate into the DART ion source at a constant velocity, a syringe pump was employed. The DART-MS total ion current chromatogram was recorded for the entire TLC plate. The concentration of each lignan compound was calculated from the calibration curve established with standard compound. Gomisin A, gomisin N and schisandrin were well separated on a silica-coated TLC plate and the specific ion current chromatograms were successfully acquired from the TLC-DART-MS system. The TLC-DART-MS system for the quantitation of natural products showed better linearity and specificity than TLC densitometry, and consumed less time and solvent than conventional HPLC method. A hyphenated system for the quantitation of phytochemicals from crude herbal drugs was successfully established. This system was shown to have a powerful analytical capacity for the prompt and efficient quantitation of natural products from crude drugs. Copyright © 2010 John Wiley & Sons, Ltd.

First characterisation of a CPD-class I photolyase from a UV-resistant extremophile isolated from High-Altitude Andean Lakes.

PubMed

Albarracín, Virginia Helena; Simon, Julian; Pathak, Gopal P; Valle, Lorena; Douki, Thierry; Cadet, Jean; Borsarelli, Claudio Darío; Farias, María Eugenia; Gärtner, Wolfgang

2014-05-01

UV-resistant Acinetobacter sp. Ver3 isolated from High-Altitude Andean Lakes (HAAL) in Argentinean Puna, one of the highest UV exposed ecosystems on Earth, showed efficient DNA photorepairing ability, coupled to highly efficient antioxidant enzyme activities in response to UV-B stress. We herein present the cloning, expression, and functional characterization of a cyclobutane pyrimidine dimer (CPD)-class I photolyase (Ver3Phr) from this extremophile to prove its involvement in the previously noted survival capability. Spectroscopy of the overexpressed and purified protein identified flavin adenine dinucleotide (FAD) and 5,10-methenyltetrahydrofolate (MTHF) as chromophore and antenna molecules, respectively. All functional analyses were performed in parallel with the ortholog E. coli photolyase. Whereas the E. coli enzyme showed the FAD chromophore as a mixture of oxidised and reduced states, the Ver3 chromophore always remained partly (including the semiquinone state) or fully reduced under all experimental conditions tested. Functional complementation of Ver3Phr in Phr(-)-RecA E. coli strains was assessed by traditional UFC counting and measurement of DNA bipyrimidine photoproducts by HPLC coupled with electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) detection. The results identified strong photoreactivation ability in vivo of Ver3Phr while its nonphotoreactivation function, probably related with the stimulation of nucleotide excision repair (NER), was not as manifest as for EcPhr. Whether this is a question of the approach using an exogenous photolyase incorporated in a non-genuine host or a fundamental different behaviour of a novel enzyme from an exotic environment will need further studies.

Formation of an optical pulsed discharge in a supersonic air flow by radiation of a repetitively pulsed CO{sub 2} laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malov, Aleksei N; Orishich, Anatolii M

Results of optimisation of repetitively pulsed CO{sub 2}-laser generation are presented for finding physical conditions of forming stable burning of an optical pulsed discharge (OPD) in a supersonic air flow and for studying the influence of pulse parameters on the energy absorption efficiency of laser radiation in plasma. The optical discharge in a supersonic air flow was formed by radiation of a repetitively pulsed CO{sub 2} laser with mechanical Q-switching excited by a discharge with a convective cooling of the working gas. For the first time the influence of radiation pulse parameters on the ignition conditions and stable burning ofmore » the OPD in a supersonic air flow was investigated and the efficiency of laser radiation absorption in plasma was studied. The influence of the air flow velocity on stability of plasma production was investigated. It was shown that stable burning of the OPD in a supersonic flow is realised at a high pulse repetition rate where the interval between radiation pulses is shorter than the time of plasma blowing-off. Study of the instantaneous value of the absorption coefficient shows that after a breakdown in a time lapse of 100 - 150 ns, a quasi-stationary 'absorption phase' is formed with the duration of {approx}1.5 ms, which exists independently of air flow and radiation pulse repetition rate. This phase of strong absorption is, seemingly, related to evolution of the ionisation wave. (laser applications and other topics in quantum electronics)« less

MRA of the skin: mapping for advanced breast reconstructive surgery.

PubMed

Thimmappa, N D; Vasile, J V; Ahn, C Y; Levine, J L; Prince, M R

2018-02-27

Autologous breast reconstruction using muscle-sparing free flaps are becoming increasingly popular, although microvascular free flap reconstruction has been utilised for autologous breast reconstructions for >20 years. This innovative microsurgical technique involves meticulous dissection of artery-vein bundle (perforators) responsible for perfusion of the subcutaneous fat and skin of the flap; however, due to unpredictable anatomical variations, preoperative imaging of the donor site to select appropriate perforators has become routine. Preoperative imaging also reduces operating time and enhances the surgeon's confidence in choosing the appropriate donor site for harvesting flaps. Although computed tomography angiography has been widely used for preoperative imaging, concerns over excessive exposure to ionising radiation and poor iodinated contrast agent enhancement of the intramuscular perforator course has made magnetic resonance angiography, the first choice imaging modality in our centre. Magnetic resonance angiography with specific post-processing of the images has established itself as a reliable method for mapping tiny perforator vessels. Multiple donor sites can be imaged in a single setting without concern for ionising radiation exposure. This provides anatomical information of more reconstruction donor site options, so that a surgeon can design a flap of tissue centralised around the best perforator, as well as a back-up perforator, and even a back-up flap option located on a different region of the body. This information is especially helpful in patients with a history of scar tissue from previous surgeries, where the primary choice perforator is found to be damaged or unsuitable intraoperatively. In addition, chest magnetic resonance angiography evaluates recipient site blood vessel suitability including vessel diameters, course, and branching patterns. In this article we provide a broad overview of various skin flaps, clinical indications, advantages and disadvantages of each of these flaps, basic imaging technique, along with advanced sequences for visualising tiny arteries in the groin and in the chest. Post-processing techniques, structure of the report and how automation of the reporting system improves workflow is described. We also describe applications of magnetic resonance angiography in postoperative imaging. Copyright © 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

VLF Technique and Science in India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakravarty, S. C.

2010-10-20

Since IGY period (1957-58), natural and artificially produced Very Low Frequency (VLF) electromagnetic radiations are being recorded at large number of ground stations and on board satellites to study various wave-plasma interactive phenomena. The terrestrial propagation of these VLF radio waves are primarily enabled through the earth ionosphere wave guide (EIWG) system to long horizontal distances around the globe and ducted along the geomagnetic field lines into the conjugate hemisphere through the ionosphere-plasmasphere-magnetosphere routes. The time frequency spectra indicate presence of dispersion and various cut-off frequencies providing several types of received signals like whistlers, chorus, tweeks, hiss, hisslers etc., whichmore » can be heard on an earphone with distinguishing audio structures. While the VLF technique has been a very effective tool for studying middle and high latitude phenomena, the importance of various anomalous characteristics over the Indian low latitude stations provide potentially new challenges for their scientific interpretation and modelling. The ducted and non-ducted propagation, low latitude TRIMPI/TLE effects, D-region ionisation perturbations due to solar and stellar x- and {gamma} ray emissions and detecting precursors of seismic activities are a few problems which will gain from low latitude studies. Since the conjugate points of Indian stations lie over the Indian oceanic region, the VLF propagation effects would be relatively noise free to observe rare and new phenomena requiring better SNR to detect such changes. The VLF signals emanating from the active seismic zones would require high sensitivity of the system and suitable network of transmitting and receiving stations. Results obtained on whistlers and related studies from a number of Indian stations covering geomagnetic latitude range between 13-24 deg. N are mentioned and reviewed in the background of theoretical understanding of the lightning return stroke signal elements, VLF propagation through cold plasma, ionospheric wave guide mode, electron precipitation due to cyclotron resonance and production of ionisation in the D-region due to solar/stellar UV/X/{gamma}-rays. Further use of the VLF technique in terms of improving both observational data for real time monitoring/modelling of geophysical phenomena and exploring space weather conditions are considered as part of a future Indian programme.« less

VLF Technique and Science in India

NASA Astrophysics Data System (ADS)

Chakravarty, S. C.

2010-10-01

Since IGY period (1957-58), natural and artificially produced Very Low Frequency (VLF) electromagnetic radiations are being recorded at large number of ground stations and on board satellites to study various wave-plasma interactive phenomena. The terrestrial propagation of these VLF radio waves are primarily enabled through the earth ionosphere wave guide (EIWG) system to long horizontal distances around the globe and ducted along the geomagnetic field lines into the conjugate hemisphere through the ionosphere-plasmasphere-magnetosphere routes. The time frequency spectra indicate presence of dispersion and various cut-off frequencies providing several types of received signals like whistlers, chorus, tweeks, hiss, hisslers etc., which can be heard on an earphone with distinguishing audio structures. While the VLF technique has been a very effective tool for studying middle and high latitude phenomena, the importance of various anomalous characteristics over the Indian low latitude stations provide potentially new challenges for their scientific interpretation and modelling. The ducted and non-ducted propagation, low latitude TRIMPI/TLE effects, D-region ionisation perturbations due to solar and stellar x- and γ ray emissions and detecting precursors of seismic activities are a few problems which will gain from low latitude studies. Since the conjugate points of Indian stations lie over the Indian oceanic region, the VLF propagation effects would be relatively noise free to observe rare and new phenomena requiring better SNR to detect such changes. The VLF signals emanating from the active seismic zones would require high sensitivity of the system and suitable network of transmitting and receiving stations. Results obtained on whistlers and related studies from a number of Indian stations covering geomagnetic latitude range between 13-24 °N are mentioned and reviewed in the background of theoretical understanding of the lightning return stroke signal elements, VLF propagation through cold plasma, ionospheric wave guide mode, electron precipitation due to cyclotron resonance and production of ionisation in the D-region due to solar/stellar UV/X/γ-rays. Further use of the VLF technique in terms of improving both observational data for real time monitoring/modelling of geophysical phenomena and exploring space weather conditions are considered as part of a future Indian programme.

The VLT-FLAMES Tarantula Survey. XVII. Physical and wind properties of massive stars at the top of the main sequence

NASA Astrophysics Data System (ADS)

Bestenlehner, J. M.; Gräfener, G.; Vink, J. S.; Najarro, F.; de Koter, A.; Sana, H.; Evans, C. J.; Crowther, P. A.; Hénault-Brunet, V.; Herrero, A.; Langer, N.; Schneider, F. R. N.; Simón-Díaz, S.; Taylor, W. D.; Walborn, N. R.

2014-10-01

The evolution and fate of very massive stars (VMS) is tightly connected to their mass-loss properties. Their initial and final masses differ significantly as a result of mass loss. VMS have strong stellar winds and extremely high ionising fluxes, which are thought to be critical sources of both mechanical and radiative feedback in giant H ii regions. However, how VMS mass-loss properties change during stellar evolution is poorly understood. In the framework of the VLT-Flames Tarantula Survey (VFTS), we explore the mass-loss transition region from optically thin O star winds to denser WNh Wolf-Rayet star winds, thereby testing theoretical predictions. To this purpose we select 62 O, Of, Of/WN, and WNh stars, an unprecedented sample of stars with the highest masses and luminosities known. We perform a spectral analysis of optical VFTS as well as near-infrared VLT/SINFONI data using the non-LTE radiative transfer code CMFGEN to obtain both stellar and wind parameters. For the first time, we observationally resolve the transition between optically thin O star winds and optically thick hydrogen-rich WNh Wolf-Rayet winds. Our results suggest the existence of a "kink" between both mass-loss regimes, in agreement with recent Monte Carlo simulations. For the optically thick regime, we confirm the steep dependence on the classical Eddington factor Γe from previous theoretical and observational studies. The transition occurs on the main sequence near a luminosity of 106.1L⊙, or a mass of 80 ... 90 M⊙. Above this limit, we find that - even when accounting for moderate wind clumping (with fv = 0.1) - wind mass-loss rates are enhanced with respect to standard prescriptions currently adopted in stellar evolution calculations. We also show that this results in substantial helium surface enrichment. Finally, based on our spectroscopic analyses, we are able to provide the most accurate ionising fluxes for VMS known to date, confirming the pivotal role of VMS in ionising and shaping their environments. Appendices are available in electronic form at http://www.aanda.org

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE). II. Constraining the quenching time in the stripped galaxy NGC 4330

NASA Astrophysics Data System (ADS)

Fossati, M.; Mendel, J. T.; Boselli, A.; Cuillandre, J. C.; Vollmer, B.; Boissier, S.; Consolandi, G.; Ferrarese, L.; Gwyn, S.; Amram, P.; Boquien, M.; Buat, V.; Burgarella, D.; Cortese, L.; Côté, P.; Côté, S.; Durrell, P.; Fumagalli, M.; Gavazzi, G.; Gomez-Lopez, J.; Hensler, G.; Koribalski, B.; Longobardi, A.; Peng, E. W.; Roediger, J.; Sun, M.; Toloba, E.

2018-06-01

The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band Hα + [NII] imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. During pilot observations taken in the spring of 2016 we observed NGC 4330, an intermediate mass (M* ≃ 109.8 M⊙) edge-on star forming spiral currently falling into the core of the Virgo cluster. While previous Hα observations showed a clumpy complex of ionised gas knots outside the galaxy disc, new deep observations revealed a low surface brightness 10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel to one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these features which indicate ongoing gas stripping, we collected literature photometry in 15 bands from the far-UV to the far-IR and deep optical long-slit spectroscopy using the FORS2 instrument at the ESO Very Large Telescope. Using a newly developed Monte Carlo code that jointly fits spectroscopy and photometry, we reconstructed the star formation histories in apertures along the major axis of the galaxy. Our results have been validated against the output of CIGALE, a fitting code which has been previously used for similar studies. We found a clear outside-in gradient with radius of the time when the quenching event started: the outermost radii were stripped 500 Myr ago, while the stripping reached the inner 5 kpc from the centre in the last 100 Myr. Regions at even smaller radii are currently still forming stars fueled by the presence of HI and H2 gas. When compared to statistical studies of the quenching timescales in the local Universe we find that ram pressure stripping of the cold gas is an effective mechanism to reduce the transformation times for galaxies falling into massive clusters. Future systematic studies of all the active galaxies observed by VESTIGE in the Virgo cluster will extend these results to a robust statistical framework.

Increased serum nonesterified fatty acid and low ionised calcium concentrations are associated with post partum colic in mares.

PubMed

Holcombe, S J; Embertson, R M; Kurtz, K A; Roessner, H A; Wismer, S E; Geor, R J; Kaneene, J B

2016-01-01

Increased serum nonesterified fatty acids (NEFA) and decreased serum electrolytes are linked to abdomasal displacements in post partum dairy cattle. Post partum colic in mares may be associated with metabolic changes specific to pregnancy and the periparturient period. To determine if fluctuations in serum NEFA, ionised calcium (iCa) and magnesium (iMg) occurred in periparturient mares and if these alterations were associated with post partum colic. Longitudinal observational study. Mares from 3 farms in central Kentucky were enrolled. Blood samples were collected 14 days prior to the estimated foaling date, within 4 days post parturition, and 14 and 28 days after foaling for batch analysis of serum NEFA, iCa and iMg. Health information was provided by farm managers and veterinarians. Data were analysed using Kruskal-Wallis χ(2) statistic for nonparametric data and a matched case/control approach. Repeated measures logistic regression models were developed. Serum NEFAs were higher at 14-1 day before foaling (mean ± s.d., mmol/l), 0.28 ± 0.12, P = 0.04 and from foaling to 4 days after foaling, 0.29 ± 0.20 (P = 0.05) in mares that developed colic compared with those that did not colic, 0.19 ± 0.05 and 0.21 ± 0.14, respectively. Ionised calcium was lower at 15-28 days post foaling in mares that showed colic, 1.50 ± 0.17 compared to mares that did not colic, 1.60 ± 0.12, P = 0.02. Risk of colic in post partum mares increased 38% for each 0.1 mmol/l increase in serum NEFA (odds ratio = 1.38, 95% confidence interval 1.06-1.81, P = 0.02). Mares with post partum colic had significantly higher serum NEFA and lower iCa prior to the colic episode compared with mares that did not develop colic. Monitoring these metabolic alterations may lead to predictive and preventive colic strategies for post partum mares. © 2015 EVJ Ltd.

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

NASA Astrophysics Data System (ADS)

Heays, A. N.; Bosman, A. D.; van Dishoeck, E. F.

2017-06-01

A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-ray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium abundances of abundant dark cloud abundances by up to a factor of two. The partial cross sections for H2O and NH3 photodissociation forming OH, O, NH2 and NH are also evaluated and lead to radiation-field-dependent branching ratios.

Improving preservice chemistry teachers' content knowledge through intervention activities

NASA Astrophysics Data System (ADS)

Wheeldon, Ruth

2017-06-01

The effect of intervention activities on the chemistry content knowledge of 92 preservice chemistry teachers (PSCT) was examined via a pre and post true/false with confidence level test focusing on ionisation energy values and the use of a common alternative conception (AC). Data were collected from three cohorts of PSCT each engaged in a one year full-time university-based teacher education programme. Comparison of pre-and post-test responses and discrimination differences between responses for each PSCT were used to identify the use of the AC and hence the efficacy of the intervention activities. Interviews with 14 of these PSCT allowed triangulation of the data. Findings suggest that the activities allow 71% of PSCT to identify this AC as non-scientific or become more confident in doing so. Interview data indicate that this rejection of this AC is sustained for 9 of the 11 PSCT whose test data indicated improvement. These data have implications for teacher education such that 2 hour intervention sessions can offer the opportunity for PSCT to develop their subject matter knowledge. As the accurate application of electrostatic concepts to electrons has wider application to bonding, these interventions offer PSCT more accurate chemical subject knowledge resources to draw on in their teaching.

Citrus aurantium Naringenin Prevents Osteosarcoma Progression and Recurrence in the Patients Who Underwent Osteosarcoma Surgery by Improving Antioxidant Capability.

PubMed

Zhang, Lirong; Xu, Xiaohua; Jiang, Tiechao; Wu, Kunzhe; Ding, Chuanbo; Liu, Zhen; Zhang, Xuanhe; Yu, Tianhua; Song, Changlong

2018-01-01

Citrus aurantium is rich in flavonoids, which may prevent osteosarcoma progression, but its related molecular mechanism remains unclear. Flavonoids were extracted from C. aurantium and purified by reparative HPLC. Each fraction was identified by using electrospray ionisation mass spectrometry (ESI-MS). Three main components (naringin, naringenin, and hesperetin) were isolated from C. aurantium . Naringenin inhibited the growth of MG-63 cells, whereas naringin and hesperetin had no inhibitory function on cell growth. ROS production was increased in naringin- and hesperetin-treated groups after one day of culture while the level was always lowest in the naringenin-treated group after three days of culture. 95 osteosarcoma patients who underwent surgery were assigned into two groups: naringenin group (NG, received 20 mg naringenin daily, n = 47) and control group (CG, received 20 mg placebo daily, n = 48). After an average of two-year follow-up, osteosarcoma volumes were smaller in the NG group than in the CG group ( P > 0.01). The rate of osteosarcoma recurrence was also lower in the NG group than in CG group. ROS levels were lower in the NG group than in the CG group. Thus, naringenin from Citrus aurantium inhibits osteosarcoma progression and local recurrence in the patients who underwent osteosarcoma surgery by improving antioxidant capability.

Recent developments in capabilities for analysing chlorinated paraffins in environmental matrices: A review.

PubMed

van Mourik, Louise M; Leonards, Pim E G; Gaus, Caroline; de Boer, Jacob

2015-10-01

Concerns about the high production volumes, persistency, bioaccumulation potential and toxicity of chlorinated paraffin (CP) mixtures, especially short-chain CPs (SCCPs), are rising. However, information on their levels and fate in the environment is still insufficient, impeding international classifications and regulations. This knowledge gap is mainly due to the difficulties that arise with CP analysis, in particular the chromatographic separation within CPs and between CPs and other compounds. No fully validated routine analytical method is available yet and only semi-quantitative analysis is possible, although the number of studies reporting new and improved methods have rapidly increased since 2010. Better cleanup procedures that remove interfering compounds, and new instrumental techniques, which distinguish between medium-chain CPs (MCCPs) and SCCPs, have been developed. While gas chromatography coupled to an electron capture negative ionisation mass spectrometry (GC/ECNI-MS) remains the most commonly applied technique, novel and promising use of high resolution time of flight MS (TOF-MS) has also been reported. We expect that recent developments in high resolution TOF-MS and Orbitrap technologies will further improve the detection of CPs, including long-chain CPs (LCCPs), and the group separation and quantification of CP homologues. Also, new CP quantification methods have emerged, including the use of mathematical algorithms, multiple linear regression and principal component analysis. These quantification advancements are also reflected in considerably improved interlaboratory agreements since 2010. Analysis of lower chlorinated paraffins (

Energy dependent track structure parametrisations for protons and carbon ions based on nanometric simulations

NASA Astrophysics Data System (ADS)

Alexander, Frauke; Villagrasa, Carmen; Rabus, Hans; Wilkens, Jan J.

2015-09-01

The BioQuaRT project within the European Metrology Research Programme aims at correlating ion track structure characteristics with the biological effects of radiation and develops measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigate methods to translate track-structure quantities derived on a nanometre scale to macroscopic dimensions. Input data sets were generated by simulations of ion tracks of protons and carbon ions in liquid water using the Geant 4 Monte Carlo toolkit with the Geant4-DNA processes. Based on the energy transfer points - recorded with nanometre resolution - we investigated parametrisations of overall properties of ion track structure. Three different track structure parametrisations have been developed using the distances to the 10 next neighbouring ionisations, the radial energy distribution and ionisation cluster size distributions. These parametrisations of nanometric track structure build a basis for deriving biologically relevant mean values which are essential in the clinical situation where each voxel is exposed to a mixed radiation field. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bockris, J.O.; Devanathan, M.A.V.

The galvanostatic double charging method was applied to determine the coverage of Ni cathodes with adsorbed atomic H in 2 N NaOH solutions. Anodic current densities were varied from 0.05 to 1.8 amp/sq cm. The plateau indicating absence of readsorption was between 0.6 and 1.8 amp/sq cm, for a constant cathodic c.d. of 1/10,000 amp/sq cm. The variation of the adsorbed H over cathodic c.d.'s ranging from 10 to the -6th power to 1/10 at a constant anodic c.d. of 1 amp/sq cm were calculated and the coverage calculated. The mechanism of the H evolution reaction was elucidated. The ratemore » determining step is discharge from a water molecules followed by rapid Tafel recombination. The rate constants for these processes and the rate constant for the ionisation, calculated with the extrapolated value of coverage for the reversible H electrode, were determined. A modification of the Tafel equation which takes into account both coverage and ionisation is in harmony with the results. A new method for the determination of coverage suitable for corrodible metals is described which involves the measurement of the rate of permeation of H by electrochemical techniques which enhances the sensitivity of the method. (Author)« less

Role of second-sphere coordination in anion binding: Synthesis, characterization and X-ray structure of hexaamminecobalt(III) chloride hydrogen phthalate trihydrate and sodium hexaamminecobalt(III) benzoate monohydrate

NASA Astrophysics Data System (ADS)

Sharma, Raj Pal; Bala, Ritu; Sharma, Rajni; Kariuki, B. M.; Rychlewska, Urszula; Warżajtis, Beata

2005-06-01

In an effort to utilize [Co(NH 3) 6] 3+cation as a new host for carboxylate ions, orange coloured crystalline solids of composition [Co(NH 3) 6]Cl(C 8H 5O 4) 2·3H 2O ( 1) and Na[Co(NH 3) 6](C 7H 5O 2) 4·H 2O ( 2) were obtained by reacting hot aqueous solutions of hexaamminecobalt(III) chloride with potassium hydrogen phthalate and sodium benzoate in 1:3 molar ratio, respectively. The title complex salts were characterized by elemental analyses and spectroscopic studies (IR, UV/Visible and NMR). Single crystal X-ray structure determinations revealed the formation of second-sphere coordination complexes based on hydrogen bond interactions. In complex salt 1 only two out of three ionisable chloride ions present in [Co(NH 3) 6]Cl 3 were replaced by two CHO4- ions whereas in complex salt 2 all the three ionisable chloride ions present in [Co(NH 3) 6]Cl 3 were replaced and the final product was an adduct with another mole of sodium benzoate in solid state. The crystal lattice is stabilized by electrostatic forces of attraction and predominantly N-H⋯O interactions.

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

NASA Astrophysics Data System (ADS)

Bero, M. A.; Abukassem, I.

2009-05-01

Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

Simultaneous determination of 16 brominated flame retardants in food and feed of animal origin by fast gas chromatography coupled to tandem mass spectrometry using atmospheric pressure chemical ionisation.

PubMed

Bichon, E; Guiffard, I; Vénisseau, A; Lesquin, E; Vaccher, V; Brosseaud, A; Marchand, P; Le Bizec, B

2016-08-12

A gas chromatography tandem mass spectrometry method using atmospheric pressure chemical ionisation was developed for the monitoring of 16 brominated flame retardants (7 usually monitored polybromodiphenylethers (PBDEs) and BDE #209 and 8 additional emerging and novel BFRs) in food and feed of animal origin. The developed analytical method has decreased the run time by three compared to conventional strategies, using a 2.5m column length (5% phenyl stationary phase, 0.1mm i.d., 0.1μmf.t.), a pulsed split injection (1:5) with carrier gas helium flow rate at 0.48mLmin(-1) in one run of 20 min. For most BFRs, analytical data were compared with the current analytical strategy relying on GC/EI/HRMS (double sector, R=10000 at 10% valley). Performances in terms of sensitivity were found to meet the Commission recommendation (118/2014/EC) for nBFRs. GC/APCI/MS/MS represents a promising alternative for multi-BFRs analysis in complex matrices, in that it allows the monitoring of a wider list of contaminants in a single injection and a shorter run time. Copyright © 2016 Elsevier B.V. All rights reserved.

When shape matters: Correcting the ICFs to derive the chemical abundances of bipolar and elliptical PNe

NASA Astrophysics Data System (ADS)

Gonçalves, Denise R.; Wesson, Roger; Morisset, Cristophe; Barlow, Michael; Ercolano, Barbara

2012-08-01

The extraction of chemical abundances of ionised nebulae from a limited spectral range is usually hampered by the lack of emission lines corresponding to certain ionic stages. So far, the missing emission lines have been accounted for by the ionisation correction factors (ICFs), constructed under simplistic assumptions like spherical geometry by using 1-D photoionisation modelling. In this contribution we discuss the results (Gonçalves et al. 2011, in prep.) of our ongoing project to find a new set of ICFs to determine total abundances of N, O, Ne, Ar, and S, with optical spectra, in the case of non-spherical PNe. These results are based on a grid of 3-D photoionisation modelling of round, elliptical and bipolar shaped PNe, spanning the typical PN luminosities, effective temperatures and densities. We show that the additional corrections to the widely used Kingsburgh & Barlow (1994) ICFs are always higher for bipolars than for ellipticals. Moreover, these additional corrections are, for bipolars, up to: 17% for oxygen, 33% for nitrogen, 40% for neon, 28% for argon and 50% for sulphur. Finally, on top of the fact that corrections change greatly with shape, they vary also greatly with the central star temperature, while the luminosity is a less important parameter.

Immortalisation of a human diploid fibroblast cell strain: a DT-diaphorase paradox.

PubMed Central

Kuehl, B. L.; Brezden, C. B.; Traver, R. D.; Siegel, D.; Ross, D.; Renzing, J.; Rauth, A. M.

1996-01-01

Transfection of a normal human diploid fibroblast cell strain, GM38, with a simian virus 40 (SV40) large T antigen containing plasmid, yielded an immortal cell line, G38-8X, which had a similar sensitivity as the parental cell strain to the quinone-containing chemotherapeutic agent mitomycin C (MMC), under both aerobic and hypoxic exposure conditions. The activity level of DT-diaphorase was similar in both the parental GM38 and G38-8X cells. Although DT-diaphorase could be detected by Western blot analysis, using two mouse anti-human monoclonal antibodies, in GM38 cells, it was not detected in the G38-8X cells. G38-8X cells have a slightly increased P450R activity (2-fold), and have elevated P-glycoprotein levels compared with the parental GM38 cell strain. The immortal G38-8X cell line is 2-fold more resistant to ionising radiation than the parental GM38 cell strain (D10 approximately 5 Gy). Although these SV40 large T antigen immortalised human diploid fibroblasts behaved similarly to their parental cell strain in terms of MMC sensitivity and DT-diaphorase activity, careful characterisation revealed that these cells had enhanced P-glycoprotein activity and had a decreased sensitivity to ionising radiation. Images Figure 3 PMID:8763839

Mass spectrometric behaviour of carboxylated polyethylene glycols and carboxylated octylphenol ethoxylates.

PubMed

Frańska, Magdalena; Zgoła, Agnieszka; Rychłowska, Joanna; Szymański, Andrzej; Łukaszewski, Zenon; Frański, Rafał

2003-01-01

Mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) are discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali metal cations) of carboxylated PEGs was compared with that of non-carboxylated correspondents by using both secondary ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral correspondents, PEGs. The B/E mass spectra were recorded, using secondary ion mass spectrometry as a method for generation, for deprotonated and protonated molecules and molecules cationised by alkali metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxylic groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H](-) ions proceed through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain leading to the octylphenoxy anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative ion mode were found to be more suitable for the determination of the average molecular weight of carboxylated ethoxylates than SI mass spectra.

Molecular DNA-based detection of ionising radiation in meat.

PubMed

Şakalar, Ergün

2017-05-01

Ionising radiation induces molecular alterations, such as formation of ions, free radicals, and new stable molecules, and cleavage of the chemical bonds of the molecules present in food. Irradiation-treated meat should be labelled to control the process and to ensure free consumer choice. Therefore, sensitive analytical methods are required to detect the irradiation dose. Meat samples were exposed to radiation doses of 0, 0.272, 0.497, 1.063, 3.64, 8.82 and 17.42 kGy in an industrial 60 Co gamma cell. Primers were designed to amplify 998, 498 and 250-base pair (bp) regions of the 18S rRNA gene of nuclear DNA from the irradiated samples. A new DNA-based method was developed to quantify the radiation exposed to the unstored meat and the meat stored at -20 °C for 3 and 6 months. The method was able to detect meat samples stored and unstored with dose limits of 1.063 and 3.64 kGy, respectively. The level of irradiation can be detected using primer pairs that target particularly different-sized sequences for DNA amplification by PCR. This method can be widely used for the analysis of not only meat samples, but also all biological materials containing DNA. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Dose rate constants for the quantity Hp(3) for frequently used radionuclides in nuclear medicine.

PubMed

Szermerski, Bastian; Bruchmann, Iris; Behrens, Rolf; Geworski, Lilli

2016-12-01

According to recent studies, the human eye lens is more sensitive to ionising radiation than previously assumed. Therefore, the dose limit for personnel occupationally exposed to ionising radiation will be lowered from currently 150 mSv to 20 mSv per year. Currently, no data base for a reliable estimation of the dose to the lens of the eye is available for nuclear medicine. Furthermore, the dose is usually not monitored. The aim of this work was to determine dose rate constants for the quantity H p (3), which is supposed to estimate the dose to the lens of the eye. For this, H p (3)-dosemeters were fixed to an Alderson Phantom at different positions. The dosemeters were exposed to radiation from nuclides typically used in nuclear medicine in their geometries analog to their application in nuclear medicine, e.g. syringe or vial. The results show that the handling of high-energy beta (i.e. electron or positron) emitters may lead to a relevant dose to the lens of the eye. For low-energy beta emitters and gamma emitters, an exceeding of the lowered dose limit seems to be unlikely. Copyright © 2015. Published by Elsevier GmbH.

Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbO x film growth

DOE PAGES

Franz, Robert; Clavero, César; Kolbeck, Jonathan; ...

2016-01-21

Here, the ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +E x B thanmore » in -E x B direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. NbO x thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +E x B than in -E x B direction.« less

Molecular characterisation of murine acute myeloid leukaemia induced by 56Fe ion and 137Cs gamma ray irradiation.

PubMed

Steffen, Leta S; Bacher, Jeffery W; Peng, Yuanlin; Le, Phuong N; Ding, Liang-Hao; Genik, Paula C; Ray, F Andrew; Bedford, Joel S; Fallgren, Christina M; Bailey, Susan M; Ullrich, Robert L; Weil, Michael M; Story, Michael D

2013-01-01

Exposure to sparsely ionising gamma- or X-ray irradiation is known to increase the risk of leukaemia in humans. However, heavy ion radiotherapy and extended space exploration will expose humans to densely ionising high linear energy transfer (LET) radiation for which there is currently no understanding of leukaemia risk. Murine models have implicated chromosomal deletion that includes the hematopoietic transcription factor gene, PU.1 (Sfpi1), and point mutation of the second PU.1 allele as the primary cause of low-LET radiation-induced murine acute myeloid leukaemia (rAML). Using array comparative genomic hybridisation, fluorescence in situ hybridisation and high resolution melt analysis, we have confirmed that biallelic PU.1 mutations are common in low-LET rAML, occurring in 88% of samples. Biallelic PU.1 mutations were also detected in the majority of high-LET rAML samples. Microsatellite instability was identified in 42% of all rAML samples, and 89% of samples carried increased microsatellite mutant frequencies at the single-cell level, indicative of ongoing instability. Instability was also observed cytogenetically as a 2-fold increase in chromatid-type aberrations. These data highlight the similarities in molecular characteristics of high-LET and low-LET rAML and confirm the presence of ongoing chromosomal and microsatellite instability in murine rAML.

The design of Radiation Accident Registry.

PubMed

Chen, Jing; Seely, Bob; Bergman, Lauren; Moir, Deborah

2011-03-01

In order to provide effective monitoring and follow-up on the health effects of individuals accidentally exposed to ionising radiation, a Radiation Accident Registry (RAR) has been designed and constructed as an extension to the existing National Dose Registry (NDR). The RAR has basic functions of recording, monitoring and reporting. This type of registry is able to assist responders in preparing for and managing situations during radiological events and in providing effective follow-up on the long-term health effects of persons exposed to ionising radiation. It is especially important to register radiation-exposed people in vulnerable population groups, such as children and pregnant women, to ensure proper long-term health care and protection. Even though radiation accidents are rare, a registry prepared for such accidents could involve a large population and, in some cases, require lifetime monitoring for individuals. One of the most challenging tasks associated with RAR is the assessment of radiation dose resulting from accidents. In some cases, the assessment of radiation doses to individuals could be a process requiring the involvement of various methods. The development of fast and accurate dose assessment tools will remain a long-term challenge associated with the RAR. To meet this challenge, further research activities in radiation dosimetry for individual monitoring are needed.

75 FR 27341 - Increasing Market and Planning Efficiency Through Improved Software; Notice of Technical...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-14

... Market and Planning Efficiency Through Improved Software; Notice of Technical Conference To Discuss Increasing Market and Planning Efficiency Through Improved Software May 7, 2010. Take notice that Commission... planning efficiency through improved software. [[Page 27342

Unveiling the High Energy Obscured Universe: Hunting Collapsed Objects Physics

NASA Technical Reports Server (NTRS)

Ubertini, P.; Bazzano, A.; Cocchi, M.; Natalucci, L.; Bassani, L.; Caroli, E.; Stephen, J. B.; Caraveo, P.; Mereghetti, S.; Villa, G.

2005-01-01

A large part of energy from space is coming from collapsing stars (SN, Hypernovae) and collapsed stars (black holes, neutron stars and white dwarfs). The peak of their energy release is in the hard-X and gamma-ray wavelengths where photons are insensitive to absorption and can travel from the edge the Universe or the central core of the Galaxy without loosing the primordial information of energy, time signature and polarization. The most efficient process to produce energetic photons is gravitational accretion of matter from a "normal" star onto a collapsed companion (LGxMcollxdMacc/dtx( 1Rdisc)-dMacc/dt x c2), exceeding by far the nuclear reaction capability to generate high energy quanta. Thus our natural laboratory for "in situ" investigations are collapsed objects in which matter and radiation co-exist in extreme conditions of temperature and density due to gravitationally bent geometry and magnetic fields. This is a unique opportunity to study the physics of accretion flows in stellar mass and super-massive Black Holes (SMBHs), plasmoids generated in relativistic jets in galactic microQSOs and AGNs, ionised plasma interacting at the touching point of weakly magnetized NS surface, GRB/Supernovae connection, and the mysterious origins of "dark" GRB and X-ray flash.

Label-free protein profiling of formalin-fixed paraffin-embedded (FFPE) heart tissue reveals immediate mitochondrial impairment after ionising radiation.

PubMed

Azimzadeh, Omid; Scherthan, Harry; Yentrapalli, Ramesh; Barjaktarovic, Zarko; Ueffing, Marius; Conrad, Marcus; Neff, Frauke; Calzada-Wack, Julia; Aubele, Michaela; Buske, Christian; Atkinson, Michael J; Hauck, Stefanie M; Tapio, Soile

2012-04-18

Qualitative proteome profiling of formalin-fixed, paraffin-embedded (FFPE) tissue is advancing the field of clinical proteomics. However, quantitative proteome analysis of FFPE tissue is hampered by the lack of an efficient labelling method. The usage of conventional protein labelling on FFPE tissue has turned out to be inefficient. Classical labelling targets lysine residues that are blocked by the formalin treatment. The aim of this study was to establish a quantitative proteomics analysis of FFPE tissue by combining the label-free approach with optimised protein extraction and separation conditions. As a model system we used FFPE heart tissue of control and exposed C57BL/6 mice after total body irradiation using a gamma ray dose of 3 gray. We identified 32 deregulated proteins (p≤0.05) in irradiated hearts 24h after the exposure. The proteomics data were further evaluated and validated by bioinformatics and immunoblotting investigation. In good agreement with our previous results using fresh-frozen tissue, the analysis indicated radiation-induced alterations in three main biological pathways: respiratory chain, lipid metabolism and pyruvate metabolism. The label-free approach enables the quantitative measurement of radiation-induced alterations in FFPE tissue and facilitates retrospective biomarker identification using clinical archives. Copyright © 2012 Elsevier B.V. All rights reserved.

Study on Dicarboxylic Acids in Aerosol Samples with Capillary Electrophoresis

PubMed Central

Adler, Heidi; Sirén, Heli

2014-01-01

The research was performed to study the simultaneous detection of a homologous series of α, ω-dicarboxylic acids (C2–C10), oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, with capillary electrophoresis using indirect UV detection. Good separation efficiency in 2,6-pyridinedicarboxylic acid as background electrolyte modified with myristyl trimethyl ammonium bromide was obtained. The dicarboxylic acids were ionised and separated within five minutes. For the study, authentic samples were collected onto dry cellulose membrane filters of a cascade impactor (12 stages) from outdoor spring aerosols in an urban area. Hot water and ultrasonication extraction methods were used to isolate the acids from membrane filters. Due to the low concentrations of acids in the aerosols, the extracts were concentrated with solid-phase extraction (SPE) before determination. The enrichment of the carboxylic acids was between 86 and 134% with sample pretreatment followed by 100-time increase by preparation of the sample to 50 μL. Inaccuracy was optimised for all the sample processing steps. The aerosols contained dicarboxylic acids C2–C10. Then, mostly they contained C2, C5, and C10. Only one sample contained succinic acid. In the study, the concentrations of the acids in aerosols were lower than 10 ng/m3. PMID:24729915

Simultaneous determination of 30 hormones illegally added to anti-ageing functional foods using UPLC-MS/MS coupled with SPE clean-up.

PubMed

He, Xiaoqin; Xi, Cunxian; Tang, Bobin; Wang, Guomin; Chen, Dongdong; Peng, Tao; Mu, Zhaode

2014-01-01

A novel analytical method employing solid-phase extraction (SPE) coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of 30 hormones in anti-ageing functional foods (capsules, powders and tablets). The analytes were extracted with acetic acid-acetonitrile (1-99 v/v), methanol and acetone, respectively. The extract was purified using a combined column, followed by analyte detection with electrospray ionisation in positive- or negative-ion modes. The results indicated that the 30 compounds had good linear correlations in the range of 1-1000 μg kg⁻¹, and the correlation coefficients were above 0.99. The limits of detection (LOD) and limits of quantification (LOQ) were 0.03-2 and 0.1-5 μg kg⁻¹, respectively. The average recovery of 30 compounds at the three spiked levels varied from 74.7% to 124.1%, and the relative standard deviation (RSD) was 2.4-15.0%. This method was applied to the analysis of hormones in 14 real samples of which seven hormones (such as estrone, dienestrol) were detected in four samples, but the remainder of the hormones were not detected. The developed method is sensitive, efficient, reliable and applicable to real samples.

Chloride interference in the determination of bromate in drinking water by reagent free ion chromatography with mass spectrometry detection.

PubMed

Cavalli, Silvano; Polesello, Stefano; Valsecchi, Sara

2005-08-26

Bromate, a well known by-product of the ozonation of drinking water, has been included among the substances which have to be monitored in the drinking water according to the last EC Directive 251/98 on potable water with a regulated limit of 10 microg l(-1). The need of performing routine analysis at this limit is a driving force for the developing of new simple and sensitive methods of detection, which should be also able to overcome the effect of matrix composition. This work explored the use of mass spectrometry detection with electrospray ionisation hyphenated to a reagent free ion chromatograph with hydroxide gradient elution for the determination of bromate in drinking water. The use of a high capacity hydroxide selective column operated in gradient mode allowed to avoid the interference by carbonate peak, which moved to longer retention times. The effect of increasing chloride concentrations from 0 to 250 mg l(-1), which is the guideline limit for drinking water in Directive 251/98/EC, was to decrease absolute mass spectrometric response and chromatographic efficiency and, on the consequence, to increase the effective detection limits. The effect of the chloride concentration on the detection of bromate is discussed.

Measurement of isotope ratios on transient signals by MC-ICP-MS.

PubMed

Günther-Leopold, Ines; Wernli, Beat; Kopajtic, Zlatko; Günther, Detlef

2004-01-01

Precise and accurate isotope ratio measurements are an important task in many applications such as isotope-dilution mass spectrometry, bioavailability studies, or the determination of isotope variations in geological or nuclear samples. The technique of MC-ICP-MS has attracted much attention because it permits the precise measurement of isotope compositions for a wide range of elements combined with excellent detection limits due to high ionisation efficiencies. However, the results are based mainly on measurements using continuous sample introduction. In the present study the determination of isotope ratios on various transient signals with a time duration of 30 to 60 s has been achieved by coupling high-performance liquid chromatography to a multicollector inductively coupled plasma mass spectrometer. In order to investigate the origin of ratio drifts across the transient signals for this hyphenated technique, measurements with the same standard solutions were also carried out using a flow-injection device for sample introduction. As a result of this application it could be concluded that the main source of the bias in the measured isotope ratios is within the ICP-MS instead of fractionation effects on the chromatographic column material. Preliminary studies on short transient signals of gaseous samples (dry plasma) showed a reverse fractionation effect compared with wet plasma conditions (flow injection and HPLC).

Cost-Benefit of Improving the Efficiency of Room Air Conditioners (Inverter and Fixed Speed) in India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phadke, Amol; Shah, Nihar; Abhyankar, Nikit

Improving efficiency of air conditioners (ACs) typically involves improving the efficiency of various components such as compressors, heat exchangers, expansion valves, refrigerant,and fans. We estimate the incremental cost of improving the efficiency of room ACs based on the cost of improving the efficiency of its key components. Further, we estimate the retail price increase required to cover the cost of efficiency improvement, compare it with electricity bill savings, and calculate the payback period for consumers to recover the additional price of a more efficient AC. The finding that significant efficiency improvement is cost effective from a consumer perspective is robustmore » over a wide range of assumptions. If we assume a 50% higher incremental price compared to our baseline estimate, the payback period for the efficiency level of 3.5 ISEER is 1.1 years. Given the findings of this study, establishing more stringent minimum efficiency performance criteria (one-star level) should be evaluated rigorously considering significant benefits to consumers, energy security, and environment« less

Argon purification studies and a novel liquid argon re-circulation system

NASA Astrophysics Data System (ADS)

Mavrokoridis, K.; Calland, R. G.; Coleman, J.; Lightfoot, P. K.; McCauley, N.; McCormick, K. J.; Touramanis, C.

2011-08-01

Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficiency of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O2, H2O, N2 and CO2 in the range of between 0.01 ppm to 1000 ppm - H2O was found to have the most profound effect on gaseous argon scintillation light, and N2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N2 gas and H2O vapour has been quantified using BET isotherm analysis. The efficiency of Cu and P2O5 at removing O2 and H2O impurities from 1 bar N6 argon gas at both room temperature and -130 °C was investigated and found to be high. A novel, highly scalable LAr re-circulation system has been developed. The complete system, consisting of a motorised bellows pump operating in liquid and a purification cartridge, were designed and built in-house. The system was operated successfully over many days and achieved a re-circulation rate of 27 litres/hour and high purity.

IBIC characterisation of novel detectors for single atom doping of quantum computer devices

NASA Astrophysics Data System (ADS)

Yang, Changyi; Jamieson, David N.; Pakes, Chris I.; George, Damien P.; Hearne, Sean M.; Dzurak, Andrew S.; Gauja, Eric; Stanley, F.; Clark, R. G.

2003-09-01

Single ion implantation and online detection is highly desirable for the emerging application, in which single 31P ions need to be inserted in prefabricated silicon cells to construct solid-state quantum bits (qubits). In order to fabricate qubit arrays, we have developed novel detectors that employ detector electrodes adjacent to the prefabricated cells that can detect single keV ion strikes appropriate for the fabrication of shallow phosphorus arrays. The method utilises a high purity silicon substrate with very high resistivity, a thin SiO 2 surface layer, nanometer masks for the lateral positioning single phosphorus implantation, biased electrodes applied to the surface of the silicon and sensitive electronics that can detect the charge transient from single keV ion strikes. A TCAD (Technology Computer Aided Design) software package was applied in the optimisation of the device design and simulation of the detector performance. Here we show the characterisation of these detectors using ion beam induced charge (IBIC) with a focused 2 MeV He ions in a nuclear microprobe. The IBIC imaging method in a nuclear microprobe allowed us to measure the dead-layer thickness of the detector structure (required to be very thin for successful detection of keV ions), and the spatial distribution of the charge collection efficiency around the entire region of the detector. We show that our detectors have near 100% charge collection efficiency for MeV ions, extremely thin dead-layer thickness (about 7 nm) and a wide active region extending laterally from the electrodes (10-20 μm) where qubit arrays can be constructed. We demonstrate that the device can be successfully applied in the detection of keV ionisation energy from single events of keV X-rays and keV 31P ions.

Cost-Benefit of Improving the Efficiency of Room Air Conditioners (Inverter and Fixed Speed) in India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Nihar; Abhyankar, Nikit; Park, Won Young

Improving efficiency of air conditioners (ACs) typically involves improving the efficiency of various components such as compressors, heat exchangers, expansion valves, refrigerant and fans. We estimate the incremental cost of improving the efficiency of room ACs based on the cost of improving the efficiency of its key components. Further, we estimate the retail price increase required to cover the cost of efficiency improvement, compare it with electricity bill savings, and calculate the payback period for consumers to recover the additional price of a more efficient AC. We assess several efficiency levels, two of which are summarized below in the report.more » The finding that significant efficiency improvement is cost effective from a consumer perspective is robust over a wide range of assumptions. If we assume a 50% higher incremental price compared to our baseline estimate, the payback period for the efficiency level of 3.5 ISEER is 1.1 years. Given the findings of this study, establishing more stringent minimum efficiency performance criteria (one star level) should be evaluated rigorously considering significant benefits to consumers, energy security and environment.« less

Molecular diagnostic methods for invasive fungal disease: the horizon draws nearer?

PubMed

Halliday, C L; Kidd, S E; Sorrell, T C; Chen, S C-A

2015-04-01

Rapid, accurate diagnostic laboratory tests are needed to improve clinical outcomes of invasive fungal disease (IFD). Traditional direct microscopy, culture and histological techniques constitute the 'gold standard' against which newer tests are judged. Molecular diagnostic methods, whether broad-range or fungal-specific, have great potential to enhance sensitivity and speed of IFD diagnosis, but have varying specificities. The use of PCR-based assays, DNA sequencing, and other molecular methods including those incorporating proteomic approaches such as matrix-assisted laser desorption ionisation-time of flight mass spectroscopy (MALDI-TOF MS) have shown promising results. These are used mainly to complement conventional methods since they require standardisation before widespread implementation can be recommended. None are incorporated into diagnostic criteria for defining IFD. Commercial assays may assist standardisation. This review provides an update of molecular-based diagnostic approaches applicable to biological specimens and fungal cultures in microbiology laboratories. We focus on the most common pathogens, Candida and Aspergillus, and the mucormycetes. The position of molecular-based approaches in the detection of azole and echinocandin antifungal resistance is also discussed.

Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

NASA Astrophysics Data System (ADS)

Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

2016-02-01

A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups.

Evaluating experimental molecular physics studies of radiation damage in DNA*

NASA Astrophysics Data System (ADS)

Śmiałek, Małgorzata A.

2016-11-01

The field of Atomic and Molecular Physics (AMP) is a mature field exploring the spectroscopy, excitation, ionisation of atoms and molecules in all three phases. Understanding of the spectroscopy and collisional dynamics of AMP has been fundamental to the development and application of quantum mechanics and is applied across a broad range of disparate disciplines including atmospheric sciences, astrochemistry, combustion and environmental science, and in central to core technologies such as semiconductor fabrications, nanotechnology and plasma processing. In recent years the molecular physics also started significantly contributing to the area of the radiation damage at molecular level and thus cancer therapy improvement through both experimental and theoretical advances, developing new damage measurement and analysis techniques. It is therefore worth to summarise and highlight the most prominent findings from the AMP community that contribute towards better understanding of the fundamental processes in biologically-relevant systems as well as to comment on the experimental challenges that were met for more complex investigation targets. Contribution to the Topical Issue "Low-Energy Interactions related to Atmospheric and Extreme Conditions", edited by S. Ptasinska, M. Smialek-Telega, A. Milosavljevic, B. Sivaraman.

Interlaboratory tests for low-level radioactivity measurements in France

DOE Office of Scientific and Technical Information (OSTI.GOV)

Despres, M.

In the framework of French national metrological coordination, the Laboratoire de Metrologie des Rayonnements Ionisants (LMRI) organizes every year an interlaboratory test program. The participation in these programs is on a voluntary basis and the results are presented in a nameless way. These tests concern radioactivity, neutron and dosimetry measurements. In this paper, a review of interlaboratory tests for low-level radioactivity measurements proposed by LMRI is given from 1975 to 1986. Every year, three types of tests are proposed: activity tests, multigamma tests, radioanalysis tests. For the last ten years, the number of results has been respectively 90 for activitymore » tests, 570 for multigamma tests and 400 for radioanalysis tests. The user's interest has increased, while the quality of results has improved. The deviations from LMRI's reference values are less than 3% for a restricted number of laboratories, and range between 3 and 10% for the majority of the others. The most urgent tests are for mixtures of {sup 90}Sr and activation and fission products in various matrices such as milk, grass, cereals, and sediments. 16 refs., 3 figs., 3 tabs.« less

Investigation by response surface methodology of the combined effect of pH and composition of water-methanol mixtures on the stability of curcuminoids.

PubMed

D'Archivio, Angelo Antonio; Maggi, Maria Anna

2017-03-15

Response surface methodology, coupled to a full factorial three-level experimental design, was applied to investigate the combined influence of pH (between 7.0 and 8.6) and composition of methanol-water mixtures (between 30 and 70% v/v of methanol content) on the stability of curcumin and its analogues demethoxycurcumin and bisdemethoxycurcumin. The response plots revealed that addition of methanol noticeably improved the stability of curcuminoids, this effect being both pH- and structure-dependent. In the central point of the experimental domain, half-life times of curcumin, demethoxycurcumin and bisdemethoxycurcumin were 3.8±0.2, 27±2 and 251±17h, respectively. Stability of curcuminoids increased at lower pH and higher methanol content and decreased in the opposite vertex of the experimental domain. These results can be interpreted by assuming that addition of methanol to water produces a different variation of pH of the medium and apparent pKa values of the ionisable groups of curcuminoids. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advanced flow MRI: emerging techniques and applications

PubMed Central

Markl, M.; Schnell, S.; Wu, C.; Bollache, E.; Jarvis, K.; Barker, A. J.; Robinson, J. D.; Rigsby, C. K.

2016-01-01

Magnetic resonance imaging (MRI) techniques provide non-invasive and non-ionising methods for the highly accurate anatomical depiction of the heart and vessels throughout the cardiac cycle. In addition, the intrinsic sensitivity of MRI to motion offers the unique ability to acquire spatially registered blood flow simultaneously with the morphological data, within a single measurement. In clinical routine, flow MRI is typically accomplished using methods that resolve two spatial dimensions in individual planes and encode the time-resolved velocity in one principal direction, typically oriented perpendicular to the two-dimensional (2D) section. This review describes recently developed advanced MRI flow techniques, which allow for more comprehensive evaluation of blood flow characteristics, such as real-time flow imaging, 2D multiple-venc phase contrast MRI, four-dimensional (4D) flow MRI, quantification of complex haemodynamic properties, and highly accelerated flow imaging. Emerging techniques and novel applications are explored. In addition, applications of these new techniques for the improved evaluation of cardiovascular (aorta, pulmonary arteries, congenital heart disease, atrial fibrillation, coronary arteries) as well as cerebrovascular disease (intra-cranial arteries and veins) are presented. PMID:26944696

International Symposium on Electrets (ISE 6) (6th) Held in Oxford, England on 1-3 September 1988

DTIC Science & Technology

1988-09-01

detector Heat and other electromagnetic radiation detection Micro- & millimeter waves Nerve excitation studies Optical fibre attenuation Heat generation in...Phenomena in Reslnic Eaters of 241 Photothermoplastic Devices for Application to Holographic Optical Switching J. Datndurand, C. Lacabanne, J.Y. Molsan...328 Ionisation Chambers K. Doughty and I. Fleming t-64 Electro- Optical Behaviour of Ferroelectric Liquid 334 Crystal (FLC) Mixtures H.R. Dilbal, C

Characterisation of Bacteria by Matrix- assisted Laser Desorption/Ionisation and Electrospray Mass Spectrometry.

DTIC Science & Technology

1999-12-01

pesticides trapping and preconcentration column technology developed for water analysis [132]. The SP and SPIA approach seem amenable to the characteri...American Chemical Society, Washington, DC, pp. 62-84. [14] Voorhees, K.J.; Basile , F.; Beverly, M.B.; Abbashawks, C; Hendricker, A.; Cody, R.B. and...134. [15] Basile , F.; Beverly, M.B.; Voorhees, K.J. and Hadfield, T.L. (1998), Pathogenic Bacteria: Their Detection and Differentiation by Rapid

Gold nanoparticles as novel agents for cancer therapy

PubMed Central

Jain, S; Hirst, D G; O'Sullivan, J M

2012-01-01

Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold nanoparticle research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed. PMID:22010024

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2012-03-30

... Market and Planning Efficiency Through Improved Software; Notice of Technical Conference: Increasing Real-Time and Day- Ahead Market Efficiency Through Improved Software Take notice that Commission staff will...-time and day-ahead market efficiency through improved software. A detailed agenda with the list of and...

76 FR 28022 - Increasing Market and Planning Efficiency Through Improved Software; Notice of Technical...

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2011-05-13

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Review of ultrasound image guidance in external beam radiotherapy part II: intra-fraction motion management and novel applications

NASA Astrophysics Data System (ADS)

O'Shea, Tuathan; Bamber, Jeffrey; Fontanarosa, Davide; van der Meer, Skadi; Verhaegen, Frank; Harris, Emma

2016-04-01

Imaging has become an essential tool in modern radiotherapy (RT), being used to plan dose delivery prior to treatment and verify target position before and during treatment. Ultrasound (US) imaging is cost-effective in providing excellent contrast at high resolution for depicting soft tissue targets apart from those shielded by the lungs or cranium. As a result, it is increasingly used in RT setup verification for the measurement of inter-fraction motion, the subject of Part I of this review (Fontanarosa et al 2015 Phys. Med. Biol. 60 R77-114). The combination of rapid imaging and zero ionising radiation dose makes US highly suitable for estimating intra-fraction motion. The current paper (Part II of the review) covers this topic. The basic technology for US motion estimation, and its current clinical application to the prostate, is described here, along with recent developments in robust motion-estimation algorithms, and three dimensional (3D) imaging. Together, these are likely to drive an increase in the number of future clinical studies and the range of cancer sites in which US motion management is applied. Also reviewed are selections of existing and proposed novel applications of US imaging to RT. These are driven by exciting developments in structural, functional and molecular US imaging and analytical techniques such as backscatter tissue analysis, elastography, photoacoustography, contrast-specific imaging, dynamic contrast analysis, microvascular and super-resolution imaging, and targeted microbubbles. Such techniques show promise for predicting and measuring the outcome of RT, quantifying normal tissue toxicity, improving tumour definition and defining a biological target volume that describes radiation sensitive regions of the tumour. US offers easy, low cost and efficient integration of these techniques into the RT workflow. US contrast technology also has potential to be used actively to assist RT by manipulating the tumour cell environment and by improving the delivery of radiosensitising agents. Finally, US imaging offers various ways to measure dose in 3D. If technical problems can be overcome, these hold potential for wide-dissemination of cost-effective pre-treatment dose verification and in vivo dose monitoring methods. It is concluded that US imaging could eventually contribute to all aspects of the RT workflow.

Review of ultrasound image guidance in external beam radiotherapy part II: intra-fraction motion management and novel applications.

PubMed

O'Shea, Tuathan; Bamber, Jeffrey; Fontanarosa, Davide; van der Meer, Skadi; Verhaegen, Frank; Harris, Emma

2016-04-21

Imaging has become an essential tool in modern radiotherapy (RT), being used to plan dose delivery prior to treatment and verify target position before and during treatment. Ultrasound (US) imaging is cost-effective in providing excellent contrast at high resolution for depicting soft tissue targets apart from those shielded by the lungs or cranium. As a result, it is increasingly used in RT setup verification for the measurement of inter-fraction motion, the subject of Part I of this review (Fontanarosa et al 2015 Phys. Med. Biol. 60 R77-114). The combination of rapid imaging and zero ionising radiation dose makes US highly suitable for estimating intra-fraction motion. The current paper (Part II of the review) covers this topic. The basic technology for US motion estimation, and its current clinical application to the prostate, is described here, along with recent developments in robust motion-estimation algorithms, and three dimensional (3D) imaging. Together, these are likely to drive an increase in the number of future clinical studies and the range of cancer sites in which US motion management is applied. Also reviewed are selections of existing and proposed novel applications of US imaging to RT. These are driven by exciting developments in structural, functional and molecular US imaging and analytical techniques such as backscatter tissue analysis, elastography, photoacoustography, contrast-specific imaging, dynamic contrast analysis, microvascular and super-resolution imaging, and targeted microbubbles. Such techniques show promise for predicting and measuring the outcome of RT, quantifying normal tissue toxicity, improving tumour definition and defining a biological target volume that describes radiation sensitive regions of the tumour. US offers easy, low cost and efficient integration of these techniques into the RT workflow. US contrast technology also has potential to be used actively to assist RT by manipulating the tumour cell environment and by improving the delivery of radiosensitising agents. Finally, US imaging offers various ways to measure dose in 3D. If technical problems can be overcome, these hold potential for wide-dissemination of cost-effective pre-treatment dose verification and in vivo dose monitoring methods. It is concluded that US imaging could eventually contribute to all aspects of the RT workflow.

Physical structure and dust reprocessing in a sample of HH jets

NASA Astrophysics Data System (ADS)

Podio, L.; Medves, S.; Bacciotti, F.; Eislöffel, J.; Ray, T.

2009-11-01

Context: Stellar jets are an essential ingredient of the star formation process and a wealth of information can be derived from their characteristic emission-line spectra. Aims: We investigate the physical structure and dust reprocessing in the shocks along the beam of a number of classical Herbig-Haro (HH) jets in the Orion and Lupus molecular clouds (HH 111, HH 1/2, HH 83, HH 24 M/A/E/C, and Sz68). Parameters describing plasma conditions, as well as dust content, are derived as a function of distance from the source and, for HH 111, of gas velocity. Methods: Spectral diagnostic techniques are applied to obtain the jet physical conditions (the electron and total density, ne and n_H, the ionisation fraction, x_e, and the temperature, T_e) from the ratios of selected forbidden lines. The presence of dust grains is investigated by estimating the gas-phase abundance of calcium with respect to its solar value. Results: We find the electron density varies between 0.05-4×103 cm-3, the ionisation fraction xe from 0.01-0.7, the temperature ranges between 0.6-3×104 K, and the hydrogen density between 0.01-6×104 cm-3. Interestingly, in the HH 111 jet, n_e, x_e, and Te peak in the high velocity interval (HVI) of the strongest working surfaces, confirming a prediction from shocks models. Calcium turns out to be depleted with respect to its solar value, but its gas-phase abundance is higher than estimates for the interstellar medium in Orion. The depletion is high (up to 80%) along the low-excited jets, while low or no depletion is measured in those jets which show higher excitation conditions. Moreover, for HH 111 the depletion is lower in the HVI of the fastest shock. Conclusions: Our results confirm the shock structure predicted by models and indicate that shocks occurring along jets, and presumably those present in the launch zone, only partially destroy dust grains and that the efficiency of dust reprocessing strongly depends on shock velocity. However, the high Ca gas-phase abundance estimated in some of the knots, is not well understood in terms of existing models of dust reprocessing in shocks, and indicates that the dust must have been partially reprocessed in the region where the flow originates. Based on observations collected at the European Southern Observatory, La Silla, Chile (ESO programmes 60.C-0398(A). Appendix A is only available in electronic form at http://www.aanda.org

76 FR 41790 - Increasing Market and Planning Efficiency Through Improved Software; Notice Establishing Date for...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-15

... Market and Planning Efficiency Through Improved Software; Notice Establishing Date for Comments From June... real-time and day- ahead market efficiency through improved software.\\1\\ \\1\\ Notice of technical conference: increasing real-time and day-ahead market efficiency through improved software, 76 Fed. Reg. 28...

VLT/X-Shooter spectroscopy of the afterglow of the Swift GRB 130606A. Chemical abundances and reionisation at z ~ 6

NASA Astrophysics Data System (ADS)

Hartoog, O. E.; Malesani, D.; Fynbo, J. P. U.; Goto, T.; Krühler, T.; Vreeswijk, P. M.; De Cia, A.; Xu, D.; Møller, P.; Covino, S.; D'Elia, V.; Flores, H.; Goldoni, P.; Hjorth, J.; Jakobsson, P.; Krogager, J.-K.; Kaper, L.; Ledoux, C.; Levan, A. J.; Milvang-Jensen, B.; Sollerman, J.; Sparre, M.; Tagliaferri, G.; Tanvir, N. R.; de Ugarte Postigo, A.; Vergani, S. D.; Wiersema, K.; Datson, J.; Salinas, R.; Mikkelsen, K.; Aghanim, N.

2015-08-01

Context. The reionisation of the Universe is a process that is thought to have ended around z ~ 6, as inferred from spectroscopy of distant bright background sources, such as quasars (QSO) and gamma-ray burst (GRB) afterglows. Furthermore, spectroscopy of a GRB afterglow provides insight in its host galaxy, which is often too dim and distant to study otherwise. Aims: For the Swift GRB 130606A at z = 5.913 we have obtained a high S/N spectrum covering the full optical and near-IR wavelength region at intermediate spectral resolution with VLT/X-Shooter. We aim to measure the degree of ionisation of the intergalactic medium (IGM) between z = 5.02-5.84 and to study the chemical abundance pattern and dust content of its host galaxy. Methods: We estimated the UV continuum of the GRB afterglow using a power-law extrapolation, then measured the flux decrement due to absorption at Lyα,β, and γ wavelength regions. Furthermore, we fitted the shape of the red damping wing of Lyα. The hydrogen and metal absorption lines formed in the host galaxy were fitted with Voigt profiles to obtain column densities. We investigated whether ionisation corrections needed to be applied. Results: Our measurements of the Lyα-forest optical depth are consistent with previous measurements of QSOs, but have a much smaller uncertainty. The analysis of the red damping wing yields a neutral fraction xH i< 0.05 (3σ). We obtain column density measurements of H, Al, Si, and Fe; for C, O, S and Ni we obtain limits. The ionisation due to the GRB is estimated to be negligible (corrections <0.03 dex), but larger corrections may apply due to the pre-existing radiation field (up to 0.4 dex based on sub-DLA studies). Assuming that [ Si/Fe ] = +0.79 ± 0.13 is due to dust depletion, the dust-to-metal ratio is similar to the Galactic value. Conclusions: Our measurements confirm that the Universe is already predominantly ionised over the redshift range probed in this work, but was slightly more neutral at z> 5.6. GRBs are useful probes of the ionisation state of the IGM in the early Universe, but because of internal scatter we need a larger statistical sample to draw robust conclusions. The high [Si/Fe] in the host can be due to dust depletion, α-element enhancement, or a combination of both. The very high value of [ Al/Fe ] = 2.40 ± 0.78 might be due to a proton capture process and is probably connected to the stellar population history. We estimate the host metallicity to be -1.7 < [ M/H ] < -0.9 (2%-13% of solar). Based on observations carried out under prog. ID 091.C-0934(C) with the X-Shooter spectrograph installed at the Cassegrain focus of the Very Large Telescope (VLT), Unit 2 - Kueyen, operated by the European Southern Observatory (ESO) on Cerro Paranal, Chile. Partly based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Partly based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, under programme A26TAC_63.Appendix A is available in electronic form at http://www.aanda.orgThe reduced spectrum (FITS file) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A139

APEX reveals glowing stellar nurseries

NASA Astrophysics Data System (ADS)

2008-11-01

Illustrating the power of submillimetre-wavelength astronomy, an APEX image reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars. Submillimetre light is the key to revealing some of the coldest material in the Universe, such as these cold, dense clouds. Glowing Stellar Nurseries ESO PR Photo 40/08 Glowing Stellar Nurseries The region, called RCW120, is about 4200 light years from Earth, towards the constellation of Scorpius. A hot, massive star in its centre is emitting huge amounts of ultraviolet radiation, which ionises the surrounding gas, stripping the electrons from hydrogen atoms and producing the characteristic red glow of so-called H-alpha emission. As this ionised region expands into space, the associated shock wave sweeps up a layer of the surrounding cold interstellar gas and cosmic dust. This layer becomes unstable and collapses under its own gravity into dense clumps, forming cold, dense clouds of hydrogen where new stars are born. However, as the clouds are still very cold, with temperatures of around -250˚ Celsius, their faint heat glow can only be seen at submillimetre wavelengths. Submillimetre light is therefore vital in studying the earliest stages of the birth and life of stars. The submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope, located on the 5000 m high plateau of Chajnantor in the Chilean Atacama desert. Thanks to LABOCA's high sensitivity, astronomers were able to detect clumps of cold gas four times fainter than previously possible. Since the brightness of the clumps is a measure of their mass, this also means that astronomers can now study the formation of less massive stars than they could before. The plateau of Chajnantor is also where ESO, together with international partners, is building a next generation submillimetre telescope, ALMA, the Atacama Large Millimeter/submillimeter Array. ALMA will use over sixty 12-m antennas, linked together over distances of more than 16 km, to form a single, giant telescope. APEX is a collaboration between the Max-Planck-Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. The telescope is based on a prototype antenna constructed for the ALMA project. Operation of APEX at Chajnantor is entrusted to ESO.

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE). I. Introduction to the survey

NASA Astrophysics Data System (ADS)

Boselli, A.; Fossati, M.; Ferrarese, L.; Boissier, S.; Consolandi, G.; Longobardi, A.; Amram, P.; Balogh, M.; Barmby, P.; Boquien, M.; Boulanger, F.; Braine, J.; Buat, V.; Burgarella, D.; Combes, F.; Contini, T.; Cortese, L.; Côté, P.; Côté, S.; Cuillandre, J. C.; Drissen, L.; Epinat, B.; Fumagalli, M.; Gallagher, S.; Gavazzi, G.; Gomez-Lopez, J.; Gwyn, S.; Harris, W.; Hensler, G.; Koribalski, B.; Marcelin, M.; McConnachie, A.; Miville-Deschenes, M. A.; Navarro, J.; Patton, D.; Peng, E. W.; Plana, H.; Prantzos, N.; Robert, C.; Roediger, J.; Roehlly, Y.; Russeil, D.; Salome, P.; Sanchez-Janssen, R.; Serra, P.; Spekkens, K.; Sun, M.; Taylor, J.; Tonnesen, S.; Vollmer, B.; Willis, J.; Wozniak, H.; Burdullis, T.; Devost, D.; Mahoney, B.; Manset, N.; Petric, A.; Prunet, S.; Withington, K.

2018-06-01

The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band (NB) Hα+[NII] imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. The survey covers the whole Virgo cluster region from its core to one virial radius (104 deg2). The sensitivity of the survey is of f(Hα) 4 × 10-17 erg s-1 cm-2 (5σ detection limit) for point sources and Σ(Hα) 2 × 10-18 erg s-1 cm-2 arcsec-2 (1σ detection limit at 3 arcsec resolution) for extended sources, making VESTIGE the deepest and largest blind NB survey of a nearby cluster. This paper presents the survey in all its technical aspects, including the survey design, the observing strategy, the achieved sensitivity in both the NB Hα+[NII] and in the broad-band r filter used for the stellar continuum subtraction, the data reduction, calibration, and products, as well as its status after the first observing semester. We briefly describe the Hα properties of galaxies located in a 4 × 1 deg2 strip in the core of the cluster north of M87, where several extended tails of ionised gas are detected. This paper also lists the main scientific motivations for VESTIGE, which include the study of the effects of the environment on galaxy evolution, the fate of the stripped gas in cluster objects, the star formation process in nearby galaxies of different type and stellar mass, the determination of the Hα luminosity function and of the Hα scaling relations down to 106 M⊙ stellar mass objects, and the reconstruction of the dynamical structure of the Virgo cluster. This unique set of data will also be used to study the HII luminosity function in hundreds of galaxies, the diffuse Hα+[NII] emission of the Milky Way at high Galactic latitude, and the properties of emission line galaxies at high redshift. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France and the University of Hawaii.

Use of near infrared femtosecond lasers as sub-micron radiation microbeam for cell DNA damage and repair studies.

PubMed

Botchway, S W; Reynolds, P; Parker, A W; O'Neill, P

2010-01-01

Laser induced radiation microbeam technology for radiobiology research is undergoing rapid growth because of the increased availability and ease of use of femtosecond laser sources. The main processes involved are multiphoton absorption and/or plasma formation. The high peak powers these lasers generate make them ideal tools for depositing sub-micrometer size radiant energy within a region of a living cell nucleus to activate ionising and/or photochemically driven processes. The technique allows questions relating to the effects of low doses of radiation, the propagation and treatment of deoxyribonucleic acid (DNA) damage and repair in individual live cells as well as non-targeted cell to cell effects to be addressed. This mini-review focuses on the use of near infrared (NIR) ca. 800nm radiation to induce damage that is radically different from the early and subsequent ultraviolet microbeam techniques. Ultrafast pulsed NIR instrumentation has many benefits including the ability to eliminate issues of unspecific UV absorption by the many materials prevalent within cells. The multiphoton interaction volume also permits energy deposition beyond the diffraction limit. Work has established that the fundamental process of the damage induced by the ultrashort laser pulses is different to those induced from continuous wave light sources. Pioneering work has demonstrated that NIR laser microbeam radiation can mimic ionising radiation via multiphoton absorption within the 3D femtolitre volume of the highly focused Gaussian beam. This light-matter interaction phenomenon provides a novel optical microbeam probe for mimicking both complex ionising and UV radiation-type cell damage including double strand breaks (DSBs) and base damage. A further advantage of the pulsed laser technique is that it provides further scope for time-resolved experiments. Recently the NIR laser microbeam technique has been used to investigate the recruitment of repair proteins to the sub-micrometre size area of damage in viable cells using both immuno-fluorescent staining of gamma-H2AX (a marker for DSBs) and real-time imaging of GFP-labelled repair proteins including ATM, p53 binding protein 1 (53BP1), RAD51 and Ku 70/80 to elucidate the interaction of the two DNA DSB repair pathways, homologous recombination and the non-homologous end joining pathway. 2010 Elsevier B.V. All rights reserved.

Quantitative Studies of the Optical and UV Spectra of Galactic Early B Supergiants

NASA Technical Reports Server (NTRS)

Searle, S. C.; Prinja, R. K.; Massa, D.; Ryans, R.

2008-01-01

We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0-B5 supergiants of luminosity classes Ia, Ib, Iab, and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made. Methods. Fundamental parameters (e.g., T(sub eff), log L(sub *), mass-loss rates and CNO abundances) are derived for individual stars using CMFGEN, a nLTE, line-blanketed model atmosphere code. The impact of these newly derived parameters on the Galactic B supergiant Ten scale, mass discrepancy, and wind-momentum luminosity relation is examined. Results. The B supergiant temperature scale derived here shows a reduction of about 1000-3000 K compared to previous results using unblanketed codes. Mass-loss rate estimates are in good agreement with predicted theoretical values, and all of the 20 BO-B5 supergiants analysed show evidence of CNO processing. A mass discrepancy still exists between spectroscopic and evolutionary masses, with the largest discrepancy occuring at log (L/(solar)L approx. 5.4. The observed WLR values calculated for B0-B0.7 supergiants are higher than predicted values, whereas the reverse is true for B1-B5 supergiants. This means that the discrepancy between observed and theoretical values cannot be resolved by adopting clumped (i.e., lower) mass-loss rates as for O stars. The most surprising result is that, although CMFGEN succeeds in reproducing the optical stellar spectrum accurately, it fails to precisely reproduce key UV diagnostics, such as the N v and C IV P Cygni profiles. This problem arises because the models are not ionised enough and fail to reproduce the full extent of the observed absorption trough of the P Cygni profiles. Conclusions. Newly-derived fundamental parameters for early B supergiants are in good agreement with similar work in the field. The most significant discovery, however, is the failure of CMFGEN to predict the correct ionisation fraction for some ions. Such findings add further support to revising the current standard model of massive star winds, as our understanding of these winds is incomplete without a precise knowledge of the ionisation structure and distribution of clumping in the wind. Key words. techniques: spectroscopic - stars: mass-loss - stars: supergiants - stars: abundances - stars: atmospheres - stars: fundamental parameters

XMM-Newton X-ray spectroscopy of the high-mass X-ray binary 4U 1700-37 at low flux

NASA Astrophysics Data System (ADS)

van der Meer, A.; Kaper, L.; di Salvo, T.; Méndez, M.; van der Klis, M.; Barr, P.; Trams, N. R.

2005-03-01

We present results of a monitoring campaign of the high-mass X-ray binary system 4U 1700-37/HD 153919, carried out with XMM-Newton in February 2001. The system was observed at four orbital phase intervals, covering 37% of one 3.41-day orbit. The lightcurve includes strong flares, commonly observed in this source. We focus on three epochs in which the data are not affected by photon pile up: the eclipse, the eclipse egress and a low-flux interval in the lightcurve around orbital phase φ ˜ 0.25. The high-energy part of the continuum is modelled as a direct plus a scattered component, each represented by a power law with identical photon index (α ˜ 1.4), but with different absorption columns. We show that during the low-flux interval the continuum is strongly reduced, probably due to a reduction of the accretion rate onto the compact object. A soft excess is detected in all spectra, consistent with either another continuum component originating in the outskirts of the system or a blend of emission lines. Many fluorescence emission lines from near-neutral species and discrete recombination lines from He- and H-like species are detected during eclipse and egress. The fluorescence Fe Kα line at 6.4 keV is very prominent; a second Kα line is detected at slightly higher energies (up to 6.7 keV) and a Kβ line at 7.1 keV. In the low-flux interval the Fe Kα line at 6.4 keV is strongly (factor ˜ 30) reduced in strength. In eclipse, the Fe Kβ/Kα ratio is consistent with a value of 0.13. In egress we initially measure a higher ratio, which can be explained by a shift in energy of the Fe K-edge to ~ 7.15 keV, which is consistent with moderately ionised iron, rather than neutral iron, as expected for the stellar wind medium. The detection of recombination lines during eclipse indicates the presence of an extended ionised region surrounding the compact object. The observed increase in strength of some emission lines corresponding to higher values of the ionisation parameter ξ further substantiates this conclusion.

Gravity Does it: Redshift of Light from the Galaxies Yes, Expanding Universe NO!

NASA Astrophysics Data System (ADS)

Malhotra, Satish

2018-04-01

In the history of physics, ideas on space and time have changed the course of physics a number of times; this is another such event. We postulate 'space and time' as a flow of quantum gravity energy, having the absolute velocity c (same as velocity of light), where time is the delay in the spread of space (delay from infinite velocity flow, when there would be no time), such a flow has to have a reverse cycle, as energy creating it (howsoever large it might be has to be limited and limited energy can only create a limited space and time energy spread) and the reverse cycle is that of the creation of fundamental particles. This explanation of the universe tells us that the idea of an expanding universe is only an appearance, the argument, in brief, is as follows: One, the universe is so large that we cannot see the edges, light from the edges, the reality is non-observable. Two, the process is dark, it is beyond observation, the process of creation of charge (the reflection of light starts with it), the space energy flow process is in the range of invisible (before charge emerged); it is the elusive dark energy of the universe; we never connected space and time to flow of energy, and so did not find its connection either to its limitedness or to its dark nature (dark energy). Three, the space energy flow has a reverse process which leads to the formation of fundamental particles we have not included it in the totality of the processes of the universe, the former is the dark energy and the initial part of the reverse process—till it reaches the state of ionisation-- is dark matter. In the continuity of the cycle of space flow and its reversal to matter forms, ionisation happens at a particular point and visibility comes through along with; ionisation here is a later event (which is a part of the reverse process, enters visibility).It is this reverse process which creates fundamental particles (no big bang creation. With no idea of space as energy flow and no idea of the reverse process, physicists could never take the step in the direction of the correct understanding of the 'dark energy' or 'dark matter'.

Effects of AISI 316L corrosion products in in vitro bone formation.

PubMed

Morais, S; Sousa, J P; Fernandes, M H; Carvalho, G S; de Bruijn, J D; van Blitterswijk, C A

1998-06-01

Rat bone marrow cells were cultured in experimental conditions that favour the proliferation and differentiation of osteoblastic cells (i.e., 2.52 x 10(-4) mol l(-1) ascorbic acid, 10(-2) mol l(-1) beta-glycerophosphate and 10(-8) mol l(-1) dexamethasone) in the absence and in the presence of stainless-steel corrosion products, for a period of 18 days. An AISI 316L stainless-steel slurry (SS) was obtained by electrochemical means and the concentrations of the major metal ions, determined by atomic absorption spectrometry, were 8.78 x 10(-3) mol l(-1) of Fe, 4.31 x 10(-3) mol l(-1) of Cr and 2.56 x 10(-3) mol l(-1) of Ni. Bone marrow cells were exposed to 0.01, 0.1 and 1% of the SS and at the end of the incubation period, control and treated cultures were evaluated by histochemical assays for the identification of the presence of alkaline phosphatase and also calcium and phosphate deposition. Cultures were further observed by scanning electron microscopy. Levels of total and ionised calcium and phosphorus in the culture media collected from control and metal exposed cell cultures were also quantified. Histochemical staining showed that control cultures presented a strong reaction for the presence of alkaline phosphatase and exhibited formation of calcium and phosphates deposits. The presence of 0.01% SS caused no detectable biological effects in these cultures, 0.1% SS impaired osteoblastic behaviour and, 1% SS resulted in cell death. In the absence of bone cells, levels of total and ionised calcium and phosphorus in the control and metal added culture medium were similar throughout the incubation period. A significant decrease in the levels of ionised calcium and phosphorus were observed in the culture medium of control cultures and also in cultures exposed to 0.01% SS after two weeks of incubation, an event related with the formation of mineral calcium phosphate deposits in these cultures. In cultures grown in the presence of 0.1 and 1% SS corrosion products, levels of calcium and phosphorus were similar to those observed in the absence of cells. Results showed that stainless-steel corrosion products above certain concentrations may disturb the normal behaviour of osteoblast-like rat bone marrow cell cultures.

SpaceInn hare-and-hounds exercise: Estimation of stellar properties using space-based asteroseismic data

NASA Astrophysics Data System (ADS)

Reese, D. R.; Chaplin, W. J.; Davies, G. R.; Miglio, A.; Antia, H. M.; Ball, W. H.; Basu, S.; Buldgen, G.; Christensen-Dalsgaard, J.; Coelho, H. R.; Hekker, S.; Houdek, G.; Lebreton, Y.; Mazumdar, A.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D.; Verma, K.

2016-07-01

Context. Detailed oscillation spectra comprising individual frequencies for numerous solar-type stars and red giants are either currently available, e.g. courtesy of the CoRoT, Kepler, and K2 missions, or will become available with the upcoming NASA TESS and ESA PLATO 2.0 missions. The data can lead to a precise characterisation of these stars thereby improving our understanding of stellar evolution, exoplanetary systems, and the history of our galaxy. Aims: Our goal is to test and compare different methods for obtaining stellar properties from oscillation frequencies and spectroscopic constraints. Specifically, we would like to evaluate the accuracy of the results and reliability of the associated error bars, and to see where there is room for improvement. Methods: In the context of the SpaceInn network, we carried out a hare-and-hounds exercise in which one group, the hares, simulated observations of oscillation spectra for a set of ten artificial solar-type stars, and a number of hounds applied various methods for characterising these stars based on the data produced by the hares. Most of the hounds fell into two main groups. The first group used forward modelling (I.e. applied various search/optimisation algorithms in a stellar parameter space) whereas the second group relied on acoustic glitch signatures. Results: Results based on the forward modelling approach were accurate to 1.5% (radius), 3.9% (mass), 23% (age), 1.5% (surface gravity), and 1.8% (mean density), as based on the root mean square difference. Individual hounds reached different degrees of accuracy, some of which were substantially better than the above average values. For the two 1M⊙ stellar targets, the accuracy on the age is better than 10% thereby satisfying the requirements for the PLATO 2.0 mission. High stellar masses and atomic diffusion (which in our models does not include the effects of radiative accelerations) proved to be sources of difficulty. The average accuracies for the acoustic radii of the base of the convection zone, the He II ionisation, and the Γ1 peak located between the two He ionisation zones were 17%, 2.4%, and 1.9%, respectively. The results from the forward modelling were on average more accurate than those from the glitch fitting analysis as the latter seemed to be affected by aliasing problems for some of the targets. Conclusions: Our study indicates that forward modelling is the most accurate way of interpreting the pulsation spectra of solar-type stars. However, given its model-dependent nature, this method needs to be complemented by model-independent results from, e.g. glitch analysis. Furthermore, our results indicate that global rather than local optimisation algorithms should be used in order to obtain robust error bars.

Multidisciplinary European Low Dose Initiative (MELODI): strategic research agenda for low dose radiation risk research.

PubMed

Kreuzer, M; Auvinen, A; Cardis, E; Durante, M; Harms-Ringdahl, M; Jourdain, J R; Madas, B G; Ottolenghi, A; Pazzaglia, S; Prise, K M; Quintens, R; Sabatier, L; Bouffler, S

2018-03-01

MELODI (Multidisciplinary European Low Dose Initiative) is a European radiation protection research platform with focus on research on health risks after exposure to low-dose ionising radiation. It was founded in 2010 and currently includes 44 members from 18 countries. A major activity of MELODI is the continuous development of a long-term European Strategic Research Agenda (SRA) on low-dose risk for radiation protection. The SRA is intended to identify priorities for national and European radiation protection research programs as a basis for the preparation of competitive calls at the European level. Among those key priorities is the improvement of health risk estimates for exposures close to the dose limits for workers and to reference levels for the population in emergency situations. Another activity of MELODI is to ensure the availability of European key infrastructures for research activities, and the long-term maintenance of competences in radiation research via an integrated European approach for training and education. The MELODI SRA identifies three key research topics in low dose or low dose-rate radiation risk research: (1) dose and dose rate dependence of cancer risk, (2) radiation-induced non-cancer effects and (3) individual radiation sensitivity. The research required to improve the evidence base for each of the three key topics relates to three research lines: (1) research to improve understanding of the mechanisms contributing to radiogenic diseases, (2) epidemiological research to improve health risk evaluation of radiation exposure and (3) research to address the effects and risks associated with internal exposures, differing radiation qualities and inhomogeneous exposures. The full SRA and associated documents can be downloaded from the MELODI website ( http://www.melodi-online.eu/sra.html ).

Developing the radiation protection safety culture in the UK.

PubMed

Cole, P; Hallard, R; Broughton, J; Coates, R; Croft, J; Davies, K; Devine, I; Lewis, C; Marsden, P; Marsh, A; McGeary, R; Riley, P; Rogers, A; Rycraft, H; Shaw, A

2014-06-01

In the UK, as elsewhere, there is potential to improve how radiological challenges are addressed through improvement in, or development of, a strong radiation protection (RP) safety culture. In preliminary work in the UK, two areas have been identified as having a strong influence on UK society: the healthcare and nuclear industry sectors. Each has specific challenges, but with many overlapping common factors. Other sectors will benefit from further consideration.In order to make meaningful comparisons between these two principal sectors, this paper is primarily concerned with cultural aspects of RP in the working environment and occupational exposures rather than patient doses.The healthcare sector delivers a large collective dose to patients each year, particularly for diagnostic purposes, which continues to increase. Although patient dose is not the focus, it must be recognised that collective patient dose is inevitably linked to collective occupational exposure, especially in interventional procedures.The nuclear industry faces major challenges as work moves from operations to decommissioning on many sites. This involves restarting work in the plants responsible for the much higher radiation doses of the 1960/70s, but also performing tasks that are considerably more difficult and hazardous than those original performed in these plants.Factors which influence RP safety culture in the workplace are examined, and proposals are considered for a series of actions that may lead to an improvement in RP culture with an associated reduction in dose in many work areas. These actions include methods to improve knowledge and awareness of radiation safety, plus ways to influence management and colleagues in the workplace. The exchange of knowledge about safety culture between the nuclear industry and medical areas may act to develop RP culture in both sectors, and have a wider impact in other sectors where exposures to ionising radiations can occur.

Grey-scale ultrasonography for monitoring industrial exposure to hepatotoxic agents.

PubMed

Taylor, K J; Williams, D M; Smith, P M; Duck, B W

1975-05-31

Industrial exposure to several potentially hepatotoxic agents, such as vinyl-chloride monomer may occur, and there is a need for non-vasive, diagnostic techniques to detect and monitor progressive pathological processes in liver or spleen. Grey-scale ultrasonography permits display of detailed anatomy and pathology in the liver, portal veins, and spleen. The combination of fine resolution, non-invasiveness, absence of ionising radiation hazard, and portable equipment makes the technique ideal for screening populations at risk.

Matrix-assisted laser-induced gas-phase aggregation of C 60 oxides

NASA Astrophysics Data System (ADS)

Barrow, Mark P.; Tower, Nicole J.; Taylor ^*, , Roger; Drewello, Thomas

1998-08-01

Matrix-assisted laser desorption/ionisation of C 60 oxides, in conjunction with reflectron time-of-flight mass spectrometry, leads to an unprecedented gas-phase aggregation resulting in the formation of C 120O n- ·. products. The analysis of the product distribution obtained for oxides of varying oxygen content strongly suggests that the structures of these species are closely related to oxo-bridged isolated fullerene cages rather than to species featuring a fused giant fullerene core.

The Effects of Ionising Radiation on MEMS Silicon Strain Gauges: Preliminary Background and Methodology

DTIC Science & Technology

2006-09-01

due to the cosmic radiation background depends not only on altitude, but also on the geomagnetic latitude and on the solar cycle. The Earth’s...angles to the magnetic field, but is less effective at higher latitudes. In addition, solar flare events can have a particularly significant...adhesive can impair the formation and dispensing of a sufficiently small droplet. The solution arrived at was to use the dispenser as a form of

Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

NASA Astrophysics Data System (ADS)

Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

2017-02-01

The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research.

Comparative analyses of studies of childhood leukemia and magnetic fields, radon and gamma radiation.

PubMed

Kheifets, Leeka; Swanson, John; Yuan, Yingzhe; Kusters, Cynthia; Vergara, Ximena

2017-06-26

In this paper we compare the findings of epidemiologic studies of childhood leukemia that examined at least two of ELF magnetic fields and/or distance to power lines, and exposure to radon and gamma radiation or distance to nuclear plants. Many of the methodologic aspects are common to studies of non-ionising (i.e. ELF-MF) and ionising radiation. A systematic search and review of studies with more than one exposure under study identified 33 key and 35 supplementary papers from ten countries that have been included in this review. Examining studies that have looked at several radiation exposures, and comparing similarities and differences for the different types of radiation, through the use of directed acyclic graphs, we evaluate to what extent bias, confounding and other methodological issues might be operating in these studies. We found some indication of bias, although results are not clear cut. There is little evidence that confounding has had a substantial influence on results. Influence of the residential mobility on the study conduct and interpretation is complex and can manifest as a selection bias, confounding, increased measurement error or could also be a potential risk factor. Other factors associated with distance to power lines and to nuclear power plants should be investigated. A more complete and consistent reporting of results in the future studies will allow for a more informative comparison across studies and integration of results.

Artefactual serum hyperkalaemia and hypercalcaemia in essential thrombocythaemia

PubMed Central

Howard, M; Ashwell, S; Bond, L; Holbrook, I

2000-01-01

Aim—To investigate possible abnormalities of serum potassium and calcium levels in patients with essential thrombocythaemia and significant thrombocytosis. Methods—24 cases of essential thrombocythaemia with significant thrombocytosis (platelet count > 700 x 109/litre) had serum potassium and calcium estimations performed at the time of maximum thrombocytosis before treatment, and at the time of low platelet count after treatment with cytoreductive drugs. Selected patients were further investigated with plasma sampling and estimation of ionised calcium and parathyroid hormone. Results—At the time of maximum thrombocytosis six patients had serum hyperkalaemia (> 5.5 mmol/litre) and five had serum hypercalcaemia (> 2.6 mmol/litre). Following treatment and reduction of the platelet count, hyperkalaemia resolved in all cases and hypercalcaemia in four of the five cases. Mean serum potassium and calcium concentrations were raised (p < 0.0001) at maximum thrombocytosis compared with the values when the platelet count was low. Serum potassium and calcium values were significantly correlated at all stages. Measurements on plasma consistently corrected the hyperkalaemia but not the hypercalcaemia. Serum hypercalcaemia was associated with raised ionised calcium and normal parathyroid hormone concentrations. Conclusions—Essential thrombocythaemia with significant thrombocytosis is associated with serum hyperkalaemia and hypercalcaemia. The probable mechanism of hypercalcaemia is the secretion of calcium in vitro from an excessive number of abnormally activated platelets. It is thus likely that the hypercalcaemia is an artefact, as is the hyperkalaemia. Key Words: thrombocythaemia • hypercalcaemia • hyperkalaemia PMID:10767824

UVIT observations of the star-forming ring in NGC 7252: Evidence of possible AGN feedback suppressing central star formation

NASA Astrophysics Data System (ADS)

George, K.; Joseph, P.; Mondal, C.; Devaraj, A.; Subramaniam, A.; Stalin, C. S.; Côté, P.; Ghosh, S. K.; Hutchings, J. B.; Mohan, R.; Postma, J.; Sankarasubramanian, K.; Sreekumar, P.; Tandon, S. N.

2018-05-01

Context. Some post-merger galaxies are known to undergo a starburst phase that quickly depletes the gas reservoir and turns it into a red-sequence galaxy, though the details are still unclear. Aims: Here we explore the pattern of recent star formation in the central region of the post-merger galaxy NGC 7252 using high-resolution ultraviolet (UV) images from the UVIT on ASTROSAT. Methods: The UVIT images with 1.2 and 1.4 arcsec resolution in the FUV and NUV are used to construct a FUV-NUV colour map of the central region. Results: The FUV-NUV pixel colour map for this canonical post-merger galaxy reveals a blue circumnuclear ring of diameter 10'' (3.2 kpc) with bluer patches located over the ring. Based on a comparison to single stellar population models, we show that the ring is comprised of stellar populations with ages ≲300 Myr, with embedded star-forming clumps of younger age (≲150Myr). Conclusions: The suppressed star formation in the central region, along with the recent finding of a large amount of ionised gas, leads us to speculate that this ring may be connected to past feedback from a central super-massive black hole that has ionised the hydrogen gas in the central 4'' 1.3 kpc.

Organic superalkalis with closed-shell structure and aromaticity

NASA Astrophysics Data System (ADS)

Srivastava, Ambrish Kumar

2018-06-01

Benzene (C6H6) and polycyclic hydrocarbons such as naphthalene (C10H8), anthracene (C14H10) and coronene (C24H12) are well known aromatic organic compounds. We study the substitution of Li replacing all H-atoms in these hydrocarbons using density functional method. The vertical ionisation energy of such lithiated species, i.e. C6Li6, C10Li8, C14Li10 and C24Li12 ranges 4.24-4.50 eV, which is lower than the ionisation energy (IE) of Li atom. Thus, these species may behave as superalkalis due to their lower IE than alkali metal. However, these lithiated species possess planar and closed-shell structure, unlike typical superalkalis. Furthermore, all Li-substituted species are aromatic although their degree of aromaticity is reduced as compared to corresponding hydrocarbon analogues. We have further explored the structure of C6Li6 as star-like, unlike its inorganic analogue B3N3Li6, which appears as fan-like structure. We have also demonstrated that the interaction of C6Li6 with a superhalogen (such as BF4) is similar to that of a typical superalkali (such as OLi3). This may further suggest that the proposed lithiated species may form a new class of closed-shell organic superalkalis with aromaticity.

Analytical pyrolysis mass spectrometry: new vistas opened by temperature-resolved in-source PYMS

NASA Astrophysics Data System (ADS)

Boon, Jaap J.

1992-09-01

Analytical pyrolysis mass spectrometry (PYMS) is introduced and its applications to the analysis of synthetic polymers, biopolymers, biomacromolecular systems and geomacromolecules are critically reviewed. Analytical pyrolysis inside the ionisation chamber of a mass spectrometer, i.e. in-source PYMS, gives a complete inventory of the pyrolysis products evolved from a solid sample. The temperature-resolved nature of the experiment gives a good insight into the temperature dependence of the volatilisation and pyrolytic dissociation processes. Chemical ionisation techniques appear to be especially suitable for the analysis of oligomeric fragments released in early stages of the pyrolysis of polymer systems. Large oligomeric fragments were observed for linear polymers such as cellulose (pentadecamer), polyhydroxyoctanoic acid (tridecamer) and polyhydroxybutyric acid (heneicosamer). New in-source PYMS data are presented on artists' paints, the plant polysaccharides cellulose and xyloglucan, several microbial polyhydroxyalkanoates, wood and enzyme-digested wood, biodegraded roots and a fossil cuticle of Miocene age. On-line and off-line pyrolysis chromatography mass spectrometric approaches are also discussed. New data presented on high temperature gas chromatography--mass spectrometry of deuterio-reduced permethylated pyrolysates of cellulose lead to a better understanding of polysaccharide dissociation mechanisms. Pyrolysis as an on-line sample pretreatment method for organic macromolecules in combination with MS techniques is a very challenging field of mass spectrometry. Pyrolytic dissociation and desorption is not at all a chaotic process but proceeds according to very specific mechanisms.

Conditions for Aeronomic Applicability of the Classical Electron Heat Conduction Formula

NASA Technical Reports Server (NTRS)

Cole, K. D.; Hoegy, W. R.

1998-01-01

Conditions for the applicability of the classical formula for heat conduction in the electrons in ionized gas are investigated. In a fully ionised gas ( V(sub en) much greater than V(sub ei)), when the mean free path for electron-electron (or electron-ion) collisions is much larger than the characteristic thermal scale length of the observed system, the conditions for applicability break down. In the case of the Venus ionosphere this breakdown is indicated for a large fraction of the electron temperature data from altitudes greater than 180 km, for electron densities less than 10(exp 4)/cc cm. In a partially ionised gas such that V(sub en) much greater than V(sub ei) there is breakdown of the formula not only when the mean free path of electrons greatly exceeds the thermal scale length, but also when the gradient of neutral particle density exceeds the electron thermal gradient. It is shown that electron heat conduction may be neglected in estimating the temperature of joule heated electrons by observed strong 100 Hz electric fields when the conduction flux is limited by the saturation flux. The results of this paper support our earlier aeronomical arguments against the hypothesis of planetary scale whistlers for the 100 Hz electric field signal. In turn this means that data from the 100 Hz signal may not be used to support the case for lightning on Venus.

Simultaneous derivatisation and preconcentration of parabens in food and other matrices by isobutyl chloroformate and dispersive liquid-liquid microextraction followed by gas chromatographic analysis.

PubMed

Jain, Rajeev; Mudiam, Mohana Krishna Reddy; Chauhan, Abhishek; Ch, Ratnasekhar; Murthy, R C; Khan, Haider A

2013-11-01

A simple, rapid and economical method has been proposed for the quantitative determination of parabens (methyl, ethyl, propyl and butyl paraben) in different samples (food, cosmetics and water) based on isobutyl chloroformate (IBCF) derivatisation and preconcentration using dispersive liquid-liquid microextraction in single step. Under optimum conditions, solid samples were extracted with ethanol (disperser solvent) and 200 μL of this extract along with 50 μL of chloroform (extraction solvent) and 10 μL of IBCF was rapidly injected into 2 mL of ultra-pure water containing 150 μL of pyridine to induce formation of a cloudy state. After centrifugation, 1 μL of the sedimented phase was analysed using gas chromatograph-flame ionisation detector (GC-FID) and the peaks were confirmed using gas chromatograph-positive chemical ionisation-mass spectrometer (GC-PCI-MS). Method was found to be linear over the range of 0.1-10 μg mL(-1) with square of correlation coefficient (R(2)) in the range of 0.9913-0.9992. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.029-0.102 μg mL(-1) and 0.095-0.336 μg mL(-1) with a signal to noise ratio of 3:1 and 10:1, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Revisiting the radial abundance gradients of nitrogen and oxygen of the Milky Way

NASA Astrophysics Data System (ADS)

Esteban, C.; García-Rojas, J.

2018-05-01

We present spectra obtained with the 10.4 m Gran Telescopio Canarias telescope of 13 Galactic H II regions, most of them of very low ionisation degree. The objects are located along the Galactic disc, with RG from 5.7 to 16.1 kpc. We determine Te([N II]) for all of them. We obtain - for the first time - a radial abundance gradient of N that is independent on the ionisation correction factor. The radial distribution of the N/O ratio is almost flat, indicating that the bulk of N is not formed by standard secondary processes. We have made a reassessment of the radial O abundance gradient combining our results with previous similar ones by Esteban et al. (2017); producing a homogeneous dataset of 35 H II regions with direct determinations of the electron temperature. We report the possible presence of a flattening or drop of the O abundance in the inner part of the Galactic disc. This result confirms previous findings from metallicity distributions based on Cepheids and red giants. Finally, we find that the scatter of the N and O abundances of H II regions with respect to the gradient fittings is not substantially larger than the observational uncertainties, indicating that both chemical elements seem to be well mixed in the interstellar gas at a given distance along the Galactic disc

Time-resolved analysis of the emission of sidestream smoke (SSS) from cigarettes during smoking by photo ionisation/time-of-flight mass spectrometry (PI-TOFMS): towards a better description of environmental tobacco smoke.

PubMed

Streibel, T; Mitschke, S; Adam, T; Zimmermann, R

2013-09-01

In this study, the chemical composition of sidestream smoke (SSS) emissions of cigarettes are characterised using a laser-based single-photon ionisation time-of-flight mass spectrometer. SSS is generated from various cigarette types (2R4F research cigarette; Burley, Oriental and Virginia single-tobacco-type cigarettes) smoked on a single-port smoking machine and collected using a so-called fishtail chimney device. Using this setup, a puff-resolved quantification of several SSS components was performed. Investigations of the dynamics of SSS emissions show that concentration profiles of various substances can be categorised into several groups, either depending on the occurrence of a puff or uninfluenced by the changes in the burning zone during puffing. The SSS emissions occurring directly after a puff strongly resemble the composition of mainstream smoke (MSS). In the smouldering phase, clear differences between MSS and SSS are observed. The changed chemical profiles of SSS and MSS might be also of importance on environmental tobacco smoke which is largely determined by SSS. Additionally, the chemical composition of the SSS is strongly affected by the tobacco type. Hence, the higher nitrogen content of Burley tobacco leads to the detection of increased amounts of nitrogen-containing substances in SSS.

Benchmarking the Fundamental Electronic Properties of small TiO 2 Nanoclusters by GW and Coupled Cluster Theory Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berardo, Enrico; Kaplan, Ferdinand; Bhaskaran-Nair, Kiran

We study the vertical ionisation potential, electron affinity, fundamental gap and exciton binding energy values of small bare and hydroxylated TiO 2 nanoclusters to understand how the excited state properties change as a function of size and hydroxylation. In addition, we have employed a range of many-body methods; including G 0 W 0, qs GW, EA/IP-EOM-CCSD and DFT (B3LYP, PBE), to compare the performance and predictions of the different classes of methods. We demonstrate that for bare (i.e. non-hydroxylated) clusters all many-body methods predict the same trend with cluster size. The highest occupied and lowest unoccupied DFT orbitals follow themore » same trends as the electron affinity and ionisation potentials predicted by the many-body methods but are generally far too shallow and deep respectively in absolute terms. In contrast, the ΔDFT method is found to yield values in the correct energy window. However, its predictions depend on the functional used and do not necessarily follow trends based on the many-body methods. The effect of hydroxylation of the clusters is to open up both the optical and fundamental gap. In conclusion, a simple microscopic explanation for the observed trends with cluster size and upon hydroxylation is proposed in terms of the Madelung onsite potential.« less

The effect of basis set and exchange-correlation functional on time-dependent density functional theory calculations within the Tamm-Dancoff approximation of the x-ray emission spectroscopy of transition metal complexes.

PubMed

Roper, Ian P E; Besley, Nicholas A

2016-03-21

The simulation of X-ray emission spectra of transition metal complexes with time-dependent density functional theory (TDDFT) is investigated. X-ray emission spectra can be computed within TDDFT in conjunction with the Tamm-Dancoff approximation by using a reference determinant with a vacancy in the relevant core orbital, and these calculations can be performed using the frozen orbital approximation or with the relaxation of the orbitals of the intermediate core-ionised state included. Both standard exchange-correlation functionals and functionals specifically designed for X-ray emission spectroscopy are studied, and it is shown that the computed spectral band profiles are sensitive to the exchange-correlation functional used. The computed intensities of the spectral bands can be rationalised by considering the metal p orbital character of the valence molecular orbitals. To compute X-ray emission spectra with the correct energy scale allowing a direct comparison with experiment requires the relaxation of the core-ionised state to be included and the use of specifically designed functionals with increased amounts of Hartree-Fock exchange in conjunction with high quality basis sets. A range-corrected functional with increased Hartree-Fock exchange in the short range provides transition energies close to experiment and spectral band profiles that have a similar accuracy to those from standard functionals.

900 MHz radiation does not induce micronucleus formation in different cell types.

PubMed

Hintzsche, Henning; Jastrow, Christian; Kleine-Ostmann, Thomas; Schrader, Thorsten; Stopper, Helga

2012-07-01

The exposure of the population to non-ionising electromagnetic radiation is still increasing, mainly due to mobile communication. Whether low-intensity electromagnetic fields can cause other effects apart from heating has been a subject of debate. One of the effects, which were proposed to be caused by mobile phone radiation, is the occurrence of mitotic disturbances. The aim of this study was to investigate possible consequences of these mitotic disturbances as manifest genomic damage, i.e. micronucleus induction. Cells were irradiated at a frequency of 900 MHz, which is located in one of the main frequency bands applied for mobile communication. Two cell types were used, HaCaT cells as human cells and A(L) cells (human-hamster hybrid cells), in which mitotic disturbances had been reported to occur. After different post-exposure incubation periods, cells were fixed and micronucleus frequencies were evaluated. Both cell types did not show any genomic damage after exposure. To adapt the protocol for the micronucleus test into the direction of the protocol for mitotic disturbances, the post-exposure incubation period was reduced and exposure time was extended to one cell cycle length. This did not result in any increase of the genomic damage. In conclusion, micronucleus induction was not observed as a consequence of exposure to non-ionising radiation, even though this agent was reported to cause mitotic disturbances under similar experimental conditions.

[Nonionizing radiation and electromagnetic fields].

PubMed

Bernhardt, J H

1991-01-01

Nonionising radiation comprises all kinds of radiation and fields of the electromagnetic spectrum where biological matter is not ionised, as well as mechanical waves such as infrasound and ultrasound. The electromagnetic spectrum is subdivided into individual sections and includes: Static and low-frequency electric and magnetic fields including technical applications of energy with mains frequency, radio frequency fields, microwaves and optic radiation (infrared, visible light, ultraviolet radiation including laser). The following categories of persons can be affected by emissions by non-ionising radiation: Persons in the environment and in the household, workers, patients undergoing medical diagnosis or treatment. If the radiation is sufficiently intense, or if the fields are of appropriate strength, a multitude of effects can occur (depending on the type of radiation), such as heat and stimulating or irritating action, inflammations of the skin or eyes, changes in the blood picture, burns or in some cases cancer as a late sequel. The ability of radiation to penetrate into the human body, as well as the types of interaction with biological tissue, with organs and organisms, differs significantly for the various kinds of nonionising radiation. The following aspects of nonionising radiation are discussed: protection of humans against excessive sunlight rays when sunbathing and when exposed to UV radiation (e.g. in solaria); health risks of radio and microwaves (safety of microwave cookers and mobile radio units); effects on human health by electric and magnetic fields in everyday life.

A dual-phase xenon TPC for scintillation and ionisation yield measurements in liquid xenon

NASA Astrophysics Data System (ADS)

Baudis, Laura; Biondi, Yanina; Capelli, Chiara; Galloway, Michelle; Kazama, Shingo; Kish, Alexander; Pakarha, Payam; Piastra, Francesco; Wulf, Julien

2018-05-01

A small-scale, two-phase (liquid/gas) xenon time projection chamber ( Xurich II) was designed, constructed and is under operation at the University of Zürich. Its main purpose is to investigate the microphysics of particle interactions in liquid xenon at energies below 50 keV, which are relevant for rare event searches using xenon as target material. Here we describe in detail the detector, its associated infrastructure, and the signal identification algorithm developed for processing and analysing the data. We present the first characterisation of the new instrument with calibration data from an internal ^83{m} Kr source. The zero-field light yield is 15.0 and 14.0 photoelectrons/keV at 9.4 and 32.1 keV, respectively, and the corresponding values at an electron drift field of 1 kV/cm are 10.8 and 7.9 photoelectrons/keV. The charge yields at these energies are 28 and 31 electrons/keV, with the proportional scintillation yield of 24 photoelectrons per one electron extracted into the gas phase, and an electron lifetime of 200 μ s. The relative energy resolution, σ /E, is 11.9 and 5.8% at 9.4 and 32.1 keV, respectively using a linear combination of the scintillation and ionisation signals. We conclude with measurements of the electron drift velocity at various electric fields, and compare these to literature values.

Characterisation of a proposed internet synthesis of N,N-dimethyltryptamine using liquid chromatography/electrospray ionisation tandem mass spectrometry.

PubMed

Martins, Cláudia P B; Freeman, Sally; Alder, John F; Brandt, Simon D

2009-08-14

The psychoactive properties of N,N-dimethyltryptamine (DMT) are known to induce altered states of consciousness in humans. These properties attract great interest from clinical, neuroscientific, clandestine and forensic communities. The Breath of Hope Synthesis was reported on an internet website as a convenient two-step methodology for the preparation of DMT. The analytical characterisation of the first stage was the subject of previous publications by the authors and involved the thermal decarboxylation of tryptophan and the formation of tryptamine. The present study reports on the characterisation of the second step of this procedure which was based on the methylation of tryptamine. This employed methyl iodide and benzyltriethylammonium chloride/sodium hydroxide as a phase transfer catalyst. The reaction product was characterised by liquid chromatography/electrospray ionisation tandem mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry. Quantitative evaluation was carried out in positive multiple reaction monitoring mode (MRM), which included synthesis of the identified reaction products. MRM screening of the product did not lead to the detection of DMT. Instead, 11.1% tryptamine starting material, 21.0% N,N,N-trimethyltryptammonium iodide (TMT) and 47.4% 1-N-methyl-TMT were detected. A 0.5% trace of the monomethylated N-methyltryptamine was also detected. This study demonstrated the impact on product purity of doubtful synthetic methodologies discussed on the internet.

Benchmarking the Fundamental Electronic Properties of small TiO 2 Nanoclusters by GW and Coupled Cluster Theory Calculations

DOE PAGES

Berardo, Enrico; Kaplan, Ferdinand; Bhaskaran-Nair, Kiran; ...

2017-06-19

We study the vertical ionisation potential, electron affinity, fundamental gap and exciton binding energy values of small bare and hydroxylated TiO 2 nanoclusters to understand how the excited state properties change as a function of size and hydroxylation. In addition, we have employed a range of many-body methods; including G 0 W 0, qs GW, EA/IP-EOM-CCSD and DFT (B3LYP, PBE), to compare the performance and predictions of the different classes of methods. We demonstrate that for bare (i.e. non-hydroxylated) clusters all many-body methods predict the same trend with cluster size. The highest occupied and lowest unoccupied DFT orbitals follow themore » same trends as the electron affinity and ionisation potentials predicted by the many-body methods but are generally far too shallow and deep respectively in absolute terms. In contrast, the ΔDFT method is found to yield values in the correct energy window. However, its predictions depend on the functional used and do not necessarily follow trends based on the many-body methods. The effect of hydroxylation of the clusters is to open up both the optical and fundamental gap. In conclusion, a simple microscopic explanation for the observed trends with cluster size and upon hydroxylation is proposed in terms of the Madelung onsite potential.« less

Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

PubMed Central

Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

2017-01-01

The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research. PMID:28211480

Study of the uncertainty in estimation of the exposure of non-human biota to ionising radiation.

PubMed

Avila, R; Beresford, N A; Agüero, A; Broed, R; Brown, J; Iospje, M; Robles, B; Suañez, A

2004-12-01

Uncertainty in estimations of the exposure of non-human biota to ionising radiation may arise from a number of sources including values of the model parameters, empirical data, measurement errors and biases in the sampling. The significance of the overall uncertainty of an exposure assessment will depend on how the estimated dose compares with reference doses used for risk characterisation. In this paper, we present the results of a study of the uncertainty in estimation of the exposure of non-human biota using some of the models and parameters recommended in the FASSET methodology. The study was carried out for semi-natural terrestrial, agricultural and marine ecosystems, and for four radionuclides (137Cs, 239Pu, 129I and 237Np). The parameters of the radionuclide transfer models showed the highest sensitivity and contributed the most to the uncertainty in the predictions of doses to biota. The most important ones were related to the bioavailability and mobility of radionuclides in the environment, for example soil-to-plant transfer factors, the bioaccumulation factors for marine biota and the gut uptake fraction for terrestrial mammals. In contrast, the dose conversion coefficients showed low sensitivity and contributed little to the overall uncertainty. Radiobiological effectiveness contributed to the overall uncertainty of the dose estimations for alpha emitters although to a lesser degree than a number of transfer model parameters.

Determination of excipient based solubility increases using the CheqSol method.

PubMed

Etherson, Kelly; Halbert, Gavin; Elliott, Moira

2014-04-25

Aqueous solubility is an essential characteristic assessed during drug development to determine a compound's drug-likeness since solubility plays an important pharmaceutical role. However, nearly half of the drug candidates discovered today display poor water solubility; therefore methods have to be applied to increase solubility. Solubility determination using the CheqSol method is a novel rapid solubility screening technique for ionisable compounds. The aim of this study is to determine if the CheqSol method can be employed to determine solubility increases of four test drugs (ibuprofen, gliclazide, atenolol and propranolol) induced by non-ionising excipients such as hydroxypropyl-β-cyclodextrin and poloxamers 407 and 188. CheqSol assays were performed for the drugs alone or in combination with varying solubiliser concentrations. The measured intrinsic solubility of all four drugs increased with all the excipients tested in an excipient concentration dependent manner providing results consistent with previous literature. The results demonstrate that it may be possible to use this method to determine the solubility increases induced by non-ionic solubilising excipients with results that are comparable to standard equilibrium based solubility techniques. Since the technique is automated and requires only small drug quantities it may serve as a useful solubility or formulation screening tool providing more detailed physicochemical information than multiwell plate or similar visual systems. Copyright © 2014. Published by Elsevier B.V.

Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

NASA Astrophysics Data System (ADS)

Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

2014-07-01

We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5

Structural characterisation by both positive- and negative-ion electrospray mass spectrometry of partially methyl-esterified oligogalacturonides purified by semi-preparative high-performance anion-exchange chromatography.

PubMed

Quéméner, Bernard; Désiré, Cédric; Lahaye, Marc; Debrauwer, Laurent; Negroni, Luc

2003-01-01

The off-line coupling of high-performance anion-exchange chromatography (HPAEC) to electrospray ionisation/ion trap mass spectrometry (ESI-ITMS) is described. The Dionex carbohydrate membrane desalter (CMD) has been assessed as an on-line chromatographic desalting system to remove the high sodium concentration necessary for the HPAEC separation of partially methyl-esterified oligogalacturonides. The developed HPAEC configuration proved to be suitable for indirect coupling with ESI-ITMS. This paper provides some interesting features of positive- and negative-ion multistage tandem mass spectrometry (MS(n)) analysis of these acidic oligosaccharides. The spectra acquired in both negative- and positive-ion modes show characteristic fragment ions resulting from glycosidic bond and cross-ring cleavages. Some new mass spectrometric fragmentation routes are also described. The positive-ion mode gave more complex spectra but was as informative as the negative-ion mode. ESI-ITMS was revealed to be, as previously reported from direct use on an unseparated enzymatic digest, a powerful sequencing technique for the determination of linkage type and the methyl ester distribution of partially methyl-esterified oligogalacturonides. Moreover, unlike matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-ToF MS), it gives valuable information on the elution behaviour of these oligomers in relation to their structure, namely the HPAEC co-elution of isomeric structures.

Evidence for AGN feedback in low-mass galaxies

NASA Astrophysics Data System (ADS)

Masters, Karen; Penny, Sam; Smethurst, Rebecca; Krawczyk, Coleman; Nichol, Bob; SDSS-IV MaNGA

2018-01-01

Despite being the dominant galaxy population by number in groups and clusters, the formation and quenching mechanism of dwarf galaxies remains unknown. We present evidence for AGN feedback in a subset of 69 quenched low-mass galaxies (M* less than 5e9 Msun, fainter than Mr = -19) selected from the first two years of the MaNGA survey. The majority (85 per cent) of these quenched galaxies appear to reside in a group environment. We find 6 galaxies in our sample that appear to have an active AGN that is preventing on-going star-formation; this is the first time such a feedback mechanism has been observed in this mass range. Interestingly, five of these six galaxies have an ionised gas component that is kinematically offset from their stellar component, suggesting the gas is either recently accreted or outflowing. We hypothesise these six galaxies are low-mass equivalents to the “red geysers” observed in more massive galaxies. Of the other 62 galaxies in the sample, we find 8 do appear to have some low-level, residual star formation, or emission from hot, evolved stars. The remaining galaxies in our sample have no detectable ionised gas emission throughout their structures, consistent with them being quenched. I will show that despite being the "simplest" galaxies in our current models of galaxy formation, these quenched dwarf galaxies are a diverse population.

The management of ultrasound equipment at Sheffield Teaching Hospitals NHS Foundation Trust

PubMed Central

Peacock, M

2013-01-01

Management of ultrasound equipment at Sheffield Teaching Hospitals NHS Foundation Trust is described. The organisation and input of various stakeholders and their involvement with ultrasound equipment management and scientific ultrasound is discussed. Two important stakeholders are the Medical Equipment Management Group and the Radiation Safety Steering Committee. The Medical Equipment Management Group has a specific sub-group, the Ultrasound sub-group, and its role is to coordinate the purchase, replacement and quality assurance of ultrasound equipment in the Trust. The Radiation Safety Steering Committee has a non-ionising radiation representative and the role of this committee is to provide corporate assurance that any health and safety issues arising from the use of radiation to either patients, members of the public or staff within the Trust are being effectively managed. The Ultrasound sub-group of the Medical Equipment Management Group has successfully brought together management of all ultrasound equipment within the Trust and is in the process of fulfilling the quality assurance and training milestones set out by the Medical Equipment Management Group. Advice from the Radiation Safety Steering Committee has helped to increase awareness of ultrasound safety and good scanning practice, especially in the case of neonatal ultrasound imaging, within the Trust. In addition, the RSSC has given advice on clinical pathways for patients undergoing ionising radiation imaging while being treated by extra-corporeal shockwave lithotripsy. PMID:27433195

Biophysical modelling of early and delayed radiation damage at chromosome level

NASA Astrophysics Data System (ADS)

Andreev, S.; Eidelman, Y.

Exposure by ionising radiation increases cancer risk in human population Cancer is thought to originate from an altered expression of certain number of specific genes It is now widely recognised that chromosome aberrations CA are involved in stable change in expression of genes by gain or loss of their functions Thus CA can contribute to initiation or progression of cancer Therefore understanding mechanisms of CA formation in the course of cancer development might be valuable tool for quantification and prognosis of different stages of radiation carcinogenesis Early CA are defined as aberrations induced in first post-irradiation mitotic cycle The present work describes the original biophysical technique for early CA modelling It includes the following simulation steps the ionising particle track structure the structural organisation of all chromosomes in G 0 G 1 cell nucleus spatial distribution of radiation induced DNA double-strand breaks dsb within chromosomes dsb rejoining and misrejoining modelling cell cycle taking into account mitotic delay which results in complex time dependence of aberrant cells in first mitosis The results on prediction of dose-response curves for simple and complex CA measured in cells undergoing first division cycle are presented in comparison with recent experimental data There is increasing evidence that CA are also observed in descendents of irradiated cells many generations after direct DNA damage These delayed CA or chromosome instability CI are thought to be a manifestation of genome