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Lawrence R Walker, Malak M Tfaily, Jared B Shaw, Nancy J Hess, Ljiljana Paša-Tolić, David W Koppenaal
Under iron-limiting conditions, bacteria produce low molecular mass Fe(iii) binding molecules known as siderophores to sequester the Fe(iii), along with other elements, increasing their bioavailability. Siderophores are thought to influence iron cycling and biogeochemistry in both marine and terrestrial ecosystems and hence the need for rapid, confident characterization of these compounds has increased. In this study, the type of siderophores produced by two marine bacterial species, Synechococcus sp. PCC 7002 and Vibrio cyclitrophicus 1F53, were characterized by use of a newly developed 21 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR MS) with direct injection electrospray ionization...
December 1, 2016: Metallomics: Integrated Biometal Science
Kalevi Kairemo, Aki Kangasmäki
To the best of our knowledge, imaging of accidental exposure to radioactive fluorine-18 (F-18) due to liquid spill has not been described earlier in the scientific literature. The short half-life of F-18 (t½=110 min), current radiation safety requirements, and Good Manufacturing Practice (GMP) regulations on radiopharmaceuticals have restrained the occurrence of these incidents. The possibility of investigating this type of incidents by gamma and positron imaging is also quite limited. Additionally, a quick and precise analysis of radiochemical contamination is cumbersome and sometimes challenging if the spills of radioactive materials are low in activity...
2016: Asia Oceania Journal of Nuclear Medicine & Biology
Pouyan Jahangiri, Riley Doering, Simon Ferguson, Keana Li, Ken Buckley, François Bénard, D Mark Martinez, Cornelia Hoehr
The steady-state behaviour of a liquid target used to produce medical isotopes by low-energy cyclotrons is studied. A model based on the conservation of mass and energy is proposed to describe the pressure rise of the target assuming equilibrium between liquid and vapour phases during irradiation. The effects of water radiolysis are taken into account. Excellent agreement is achieved between the model, and both constant-temperature bath tests and experiments conducted on a 13MeV cyclotron at TRIUMF.
November 15, 2016: Applied Radiation and Isotopes
Angelo Infantino, Gianfranco Cicoria, Giulia Lucconi, Davide Pancaldi, Sara Vichi, Federico Zagni, Domiziano Mostacci, Mario Marengo
Radiation protection (RP) in the use of medical cyclotrons involves many aspects both in the routine use and for the decommissioning of a site. Guidelines for site planning and installation, as well as for RP assessment, are given in international documents; however, the latter typically offer analytic methods of calculation of shielding and materials activation, in approximate or idealised geometry set-ups. The availability of Monte Carlo (MC) codes with accurate up-to-date libraries for transport and interaction of neutrons and charged particles at energies below 250 MeV, together with the continuously increasing power of modern computers, makes the systematic use of simulations with realistic geometries possible, yielding equipment and site-specific evaluation of the source terms, shielding requirements and all quantities relevant to RP at the same time...
November 24, 2016: Radiation Protection Dosimetry
Qi Zhang, Yongrui Wang, Weilu Gao, Zhongqu Long, John D Watson, Michael J Manfra, Alexey Belyanin, Junichiro Kono
We have performed time-resolved terahertz absorption measurements on photoexcited electron-hole pairs in undoped GaAs quantum wells in magnetic fields. We probed both unbound- and bound-carrier responses via cyclotron resonance and intraexciton resonance, respectively. The stability of excitons, monitored as the pair density was systematically increased, was found to dramatically increase with increasing magnetic field. Specifically, the 1s-2p_{-} intraexciton transition at 9 T persisted up to the highest density, whereas the 1s-2p feature at 0 T was quickly replaced by a free-carrier Drude response...
November 11, 2016: Physical Review Letters
Sha Lou, Benjamin Balluff, Arjen H G Cleven, Judith V M G Bovée, Liam A McDonnell
Metabolites can be an important read-out of disease. The identification and validation of biomarkers in the cancer metabolome that can stratify high-risk patients is one of the main current research aspects. Mass spectrometry has become the technique of choice for metabolomics studies, and mass spectrometry imaging (MSI) enables their visualization in patient tissues. In this study, we used MSI to identify prognostic metabolite biomarkers in high grade sarcomas; 33 high grade sarcoma patients, comprising osteosarcoma, leiomyosarcoma, myxofibrosarcoma, and undifferentiated pleomorphic sarcoma were analyzed...
November 21, 2016: Journal of the American Society for Mass Spectrometry
Hao Dong, Wenjie Xia, Honghong Dong, Yuehui She, Panfeng Zhu, Kang Liang, Zhongzhi Zhang, Chuanfu Liang, Zhaozheng Song, Shanshan Sun, Guangqing Zhang
Biosurfactant producers are crucial for incremental oil production in microbial enhanced oil recovery (MEOR) processes. The isolation of biosurfactant-producing bacteria from oil reservoirs is important because they are considered suitable for the extreme conditions of the reservoir. In this work, a novel biosurfactant-producing strain Acinetobacter junii BD was isolated from a reservoir to reduce surface tension and emulsify crude oil. The biosurfactants produced by the strain were purified and then identified via electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS)...
2016: Frontiers in Microbiology
Jitao Lv, Shuzhen Zhang, Lei Luo, Dong Cao
Characterization of dissolved organic matter (DOM) at the molecular level will greatly improve our understanding of its bio-geochemical role in controlling the fate of contaminants in the environment, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is the most powerful analytical technique for this purpose. Before FT-ICR-MS analysis, isolation, desalination and concentration of DOM are necessary, and solid-phase extraction (SPE) is the most widely applied pretreatment procedure. However, some molecular information is lost using conventional SPE methods...
December 15, 2016: Analytica Chimica Acta
L V Kulik, A S Zhuravlev, S Dickmann, A V Gorbunov, V B Timofeev, I V Kukushkin, S Schmult
Coherent condensate states of particles obeying either Bose or Fermi statistics are in the focus of interest in modern physics. Here we report on condensation of collective excitations with Bose statistics, cyclotron magnetoexcitons, in a high-mobility two-dimensional electron system in a magnetic field. At low temperatures, the dense non-equilibrium ensemble of long-lived triplet magnetoexcitons exhibits both a drastic reduction in the viscosity and a steep enhancement in the response to the external electromagnetic field...
November 16, 2016: Nature Communications
Diane S Abou, Juile Pickett, John E Mattson, Daniel L J Thorek
The alpha particle emitter Radium-223 dichloride ((223)RaCl2) has recently been approved for treatment of late-stage bone metastatic prostate cancer. There is considerable interest in studying this new agent outside of the clinical setting, however the supply of (223)Ra is limited and expensive. We have engineered a (223)Ra microgenerator using traces of (227)Ac previously generated from cyclotron-produced (225)Ac. Radiochemically pure (223)RaCl2 was made, characterized, evaluated in vivo, and the source was recovered in high yield for regeneration of the microgenerator...
November 4, 2016: Applied Radiation and Isotopes
Olga Hrydziuszko, M Thamara P R Perera, Richard Laing, Jennifer Kirwan, Michael A Silva, Douglas A Richards, Nick Murphy, Darius F Mirza, Mark R Viant
Use of marginal liver grafts, especially those from donors after circulatory death (DCD), has been considered as a solution to organ shortage. Inferior outcomes have been attributed to donor warm ischaemic damage in these DCD organs. Here we sought to profile the metabolic mechanisms underpinning donor warm ischaemia. Non-targeted Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry metabolomics was applied to biopsies of liver grafts from donors after brain death (DBD; n = 27) and DCD (n = 10), both during static cold storage (T1) as well as post-reperfusion (T2)...
2016: PloS One
A P Povilus, N D DeTal, L T Evans, N Evetts, J Fajans, W N Hardy, E D Hunter, I Martens, F Robicheaux, S Shanman, C So, X Wang, J S Wurtele
We observe that high-Q electromagnetic cavity resonances increase the cyclotron cooling rate of pure electron plasmas held in a Penning-Malmberg trap when the electron cyclotron frequency, controlled by tuning the magnetic field, matches the frequency of standing wave modes in the cavity. For certain modes and trapping configurations, this can increase the cooling rate by factors of 10 or more. In this Letter, we investigate the variation of the cooling rate and equilibrium plasma temperatures over a wide range of parameters, including the plasma density, plasma position, electron number, and magnetic field...
October 21, 2016: Physical Review Letters
Syed M Qaim
INTRODUCTION: The significance of nuclear data in the choice and medical application of a radionuclide is considered: the decay data determine its suitability for organ imaging or internal therapy and the reaction cross section data allow optimisation of its production route. A brief discussion of reaction cross sections and yields is given. STANDARD RADIONUCLIDES: The standard SPECT, PET and therapeutic radionuclides are enumerated and their decay and production data are considered...
September 2, 2016: Nuclear Medicine and Biology
S Peter Gary, Lan K Jian, Thomas W Broiles, Michael L Stevens, John J Podesta, Justin C Kasper
Intervals of enhanced magnetic fluctuations have been frequently observed in the solar wind. But it remains an open question as to whether these waves are generated at the Sun and then transported outward by the solar wind or generated locally in the interplanetary medium. Magnetic field and plasma measurements from the Wind spacecraft under slow solar wind conditions on 19 March 2005 demonstrate seven events of enhanced magnetic fluctuations at spacecraft-frame frequencies somewhat above the proton cyclotron frequency and propagation approximately parallel or antiparallel to the background magnetic field Bo...
January 2016: Journal of Geophysical Research. Space Physics
H F-W Sadrozinski, T Geoghegan, E Harvey, R P Johnson, T E Plautz, A Zatserklyaniy, V Bashkirov, R F Hurley, P Piersimoni, R W Schulte, P Karbasi, K E Schubert, B Schultze, V Giacometti
We report on the operation and performance tests of a preclinical head scanner developed for proton computed tomography (pCT). After extensive preclinical testing, pCT is intended to be employed in support of proton therapy treatment planning and pre-treatment verification in patients undergoing particle-beam therapy. In order to assess the performance of the scanner, we have performed CT scans with 200 MeV protons from both the synchrotron of the Loma Linda University Medical Center (LLUMC) and the cyclotron of the Northwestern Medicine Chicago Proton Center (NMCPC)...
September 21, 2016: Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Xiaoyan Guan, Naomi C Brownstein, Nicolas L Young, Alan G Marshall
RATIONALE: Bottom-up tandem mass spectrometry (MS/MS) is regularly used in proteomics to identify proteins from a sequence database. De novo sequencing is also available for sequencing peptides with relatively short sequence lengths. We recently showed that paired Lys-C and Lys-N proteases produce peptides of identical mass and similar retention time, but different tandem mass spectra. Such parallel experiments provide complementary information, and allow for up to 100% MS/MS sequence coverage...
November 4, 2016: Rapid Communications in Mass Spectrometry: RCM
Arash Darafsheh, Reza Taleei, Alireza Kassaee, Jarod C Finlay
PURPOSE: Proton beam dosimetry using bare plastic optical fibers has emerged as a simple approach to proton beam dosimetry. The source of the signal in this method has been attributed to Čerenkov radiation. The aim of this work was a phenomenological study of the nature of the visible light responsible for the signal in bare fiber optic dosimetry of proton therapy beams. METHODS: Plastic fiber optic probes embedded in solid water phantoms were irradiated with proton beams of energies 100, 180, and 225 MeV produced by a proton therapy cyclotron...
November 2016: Medical Physics
X Hou, J Tanguay, M Vuckovic, K Buckley, P Schaffer, F Bénard, T J Ruth, A Celler
Cyclotron-produced (99m)Tc (CPTc) has been recognized as an attractive and practical substitution of reactor/generator based (99m)Tc. However, the small amount of (92-98)Mo in the irradiation of enriched (100)Mo could lead to the production of other radioactive technetium isotopes (Tc-impurities) which cannot be chemically separated. Thus, these impurities could contribute to patient dose and affect image quality. The potential radiation dose caused by these Tc-impurities produced using different targets, irradiation conditions, and corresponding to different injection times have been investigated, leading us to create dose-based limits of these parameters for producing clinically acceptable CPTc...
November 2, 2016: Physics in Medicine and Biology
Lucia Martiniova, Louis De Palatis, Elba Etchebehere, Gregory Ravizzini
Over the past several years, Positron Emission Tomography (PET) imaging agents labeled with 68Gallium (68Ga) have undergone a significant increase in clinical utilization. 68Ga is conveniently produced from a germanium-68/gallium-68 (68Ge/68Ga) generator. Because of the compact size and ease of use of the generator, 68Ga labeled compounds may be more cost-effective than PET radioisotopes that are cyclotron-produced. The convenient half-life of 68Ga (T1/2=68 min) provides sufficient radioactivity for various PET imaging applications, while delivering acceptable radiation doses to patients...
October 28, 2016: Current Radiopharmaceuticals
N Evetts, I Martens, D Bizzotto, D Longuevergne, W N Hardy
A microwave cavity is described which can be used to cool lepton plasmas for potential use in synthesis of antihydrogen. The cooling scheme is an incarnation of the Purcell effect: when plasmas are coupled to a microwave cavity, the plasma cooling rate is resonantly enhanced through increased spontaneous emission of cyclotron radiation. The cavity forms a three electrode section of a Penning-Malmberg trap and has a bulged cylindrical geometry with open ends aligned with the magnetic trapping axis. This allows plasmas to be injected and removed from the cavity without the need for moving parts while maintaining high quality factors for resonant modes...
October 2016: Review of Scientific Instruments
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