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https://www.readbyqxmd.com/read/29351653/calibration-of-gafchromic-ebt3-film-for-dosimetry-of-scanning-proton-pencil-beam-pbs
#1
D Krzempek, G Mianowska, N Bassler, L Stolarczyk, R Kopec, B Sas-Korczynska, P Olko
Gafchromic EBT3 films are applied in proton radiotherapy for 2D dose mapping because they demonstrate spatial resolution well below 1 mm. However, the film response must be corrected in order to reach the accuracy of dose measurements required for the clinical use. The in-house developed AnalyseGafchromic software allows to analyze and correct the measured response using triple channel dose calibration, statistical scan-to-scan fluctuations as well as experimentally determined dose and LET dependence. Finally, the optimized protocol for evaluation of response of Gafchromic EBT3 films was applied to determine 30 × 40 cm2 dose profiles of the scanning therapy unit at the Cyclotron Centre Bronowice, CCB in Krakow, Poland...
January 17, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29350938/cyclotron-orbits-of-composite-fermions-in-the-fractional-quantum-hall-regime
#2
Insun Jo, Hao Deng, Yang Liu, L N Pfeiffer, K W West, K W Baldwin, M Shayegan
We study a bilayer GaAs hole system that hosts two distinct many-body phases at low temperatures and high perpendicular magnetic fields. The higher-density (top) layer develops a Fermi sea of composite fermions (CFs) in its half-filled lowest Landau level, while the lower-density (bottom) layer forms a Wigner crystal (WC) as its filling becomes very small. Owing to the interlayer interaction, the CFs in the top layer feel the periodic Coulomb potential of the WC in the bottom layer. We measure the magnetoresistance of the top layer while changing the bottom-layer density...
January 5, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29349358/95gtc-and-96gtc-as-alternatives-to-medical-radioisotope-99mtc
#3
Takehito Hayakawa, Yuichi Hatsukawa, Toru Tanimori
We studied 95gTc and 96gTc as alternatives to the medical radioisotope 99mTc. 96gTc (95gTc) can be produced by (p, n) reactions on an enriched 96Mo (95Mo) target with a proton beam provided by a compact accelerator such as a medical cyclotron that generate radioisotopes for positron emission tomography (PET). The γ-rays are measured with an electron-tracking Compton camera (ETCC). We calculated the relative intensities of the γ-rays from 95gTc and 96gTc. The calculated γ-ray intensity of a 96gTc (95gTc) nucleus is as high as 63% (70%) of that of a 99mTc nucleus...
January 2018: Heliyon
https://www.readbyqxmd.com/read/29347491/broadening-of-cyclotron-resonance-conditions-in-the-relativistic-interaction-of-an-intense-laser-with-overdense-plasmas
#4
Takayoshi Sano, Yuki Tanaka, Natsumi Iwata, Masayasu Hata, Kunioki Mima, Masakatsu Murakami, Yasuhiko Sentoku
The interaction of dense plasmas with an intense laser under a strong external magnetic field has been investigated. When the cyclotron frequency for the ambient magnetic field is higher than the laser frequency, the laser's electromagnetic field is converted to the whistler mode that propagates along the field line. Because of the nature of the whistler wave, the laser light penetrates into dense plasmas with no cutoff density, and produces superthermal electrons through cyclotron resonance. It is found that the cyclotron resonance absorption occurs effectively under the broadened conditions, or a wider range of the external field, which is caused by the presence of relativistic electrons accelerated by the laser field...
October 2017: Physical Review. E
https://www.readbyqxmd.com/read/29340956/semi-targeted-analysis-of-complex-matrices-by-esi-ft-icr-ms-or-how-an-experimental-bias-may-be-used-as-an-analytical-tool
#5
Jasmine Hertzog, Vincent Carré, Anthony Dufour, Frédéric Aubriet
Ammonia is well suited to favor deprotonation process in electrospray ionization mass spectrometry (ESI-MS) to increase the formation of [M - H]-. Nevertheless, NH3 may react with carbonyl compounds (aldehyde, ketone) and bias the composition description of the investigated sample. This is of significant importance in the study of complex mixture such as oil or bio-oil. To assess the ability of primary amines to form imines with carbonyl compounds during the ESI-MS process, two aldehydes (vanillin and cinnamaldehyde) and two ketones (butyrophenone and trihydroxyacetophenone) have been infused in an ESI source with ammonia and two different amines (aniline and 3-chloronaniline)...
January 16, 2018: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29333470/history-and-perspectives-of-nuclear-medicine-in-myanmar
#6
Win Mar
Nuclear Medicine was established in Myanmar in 1963 by Dr Soe Myint and International Atomic Energy expert Dr R. Hochel at Yangon General Hospital. Nuclear medicine diagnostic and therapeutic services started with Probe Scintillation Detector Systems and rectilinear scanner. In the early stage, many Nuclear Medicine specialists from the International Atomic Energy Agency (IAEA) spent some time in Myanmar and made significant contributions to the development of Nuclear Medicine in our country. The department participated in various IAEA technical cooperation projects and regional cooperation projects...
2018: Asia Oceania Journal of Nuclear Medicine & Biology
https://www.readbyqxmd.com/read/29331921/cyclotron-production-of-99mtc-comparison-of-known-separation-technologies-for-isolation-of-99mtc-from-molybdenum-targets
#7
REVIEW
Magdalena Gumiela
Intensive efforts were undertaken during the last few decades for the separation of cyclotron-produced 99mTc from 99Mo and new papers have been published on this topic since the last review [1]. In the future the cyclotron-based methods can replace reactor-based technology in producing this medical radioisotope and the nuclear reaction 100Mo(p,2n)99mTc appears to be the most worthwhile approach. New ways of producing of 99mTc require efficient separation methods. Several strategies for separation of 99mTc from 99Mo have been already developed...
November 10, 2017: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29328635/adsorption-and-molecular-fractionation-of-dissolved-organic-matter-on-iron-bearing-mineral-matrices-of-varying-crystallinity
#8
Elizabeth K Coward, Tsutomu Ohno, Alain F Plante
Iron (Fe)-bearing mineral phases contribute disproportionately to adsorption of soil organic matter (SOM), due to their elevated chemical reactivity and specific surface area (SSA). However, the spectrum of Fe solid-phase speciation present in oxidation-reduction-active soils challenges analysis of SOM-mineral interactions and may induce differential molecular fractionation of dissolved organic matter (DOM). This work used paired selective dissolution experiments and batch sorption of post-extraction residues to 1) quantify the contributions of Fe-bearing minerals of varying crystallinity to DOM sorption, and 2) characterize molecular fractionation using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS)...
January 12, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29324813/increase-in-extraction-of-i-123-iomazenil-in-patients-with-chronic-cerebral-ischemia
#9
Hiroki Kato, Kayako Isohashi, Eku Shimosegawa, Jun Hatazawa
BACKGROUND: Cerebral extraction of diffusively distributed substances like oxygen has been suggested to change according to the cerebral blood flow (CBF) and status of the microvasculature. The relationships between the cerebral extraction of diffusively distributed lipophilic tracers and the severity of cerebral ischemia has not yet been clarified. In the present study, we attempted to elucidate the association between the extraction fraction of the lipophilic tracer I-123 iomazenil (IMZ) (IMZ-EF) and the oxygen extraction fraction (OEF) derived from O-15 PET in patients with chronic steno-occlusive disease of internal carotid artery (ICA) or middle cerebral artery (MCA)...
2018: PloS One
https://www.readbyqxmd.com/read/29322650/molecular-characterization-of-the-%C3%AE-amyloid-4-10-epitope-of-plaque-specific-a%C3%AE-antibodies-by-affinity-mass-spectrometry-using-alanine-site-mutation
#10
Raluca Ștefănescu, Loredana Lupu, Marilena Manea, Roxana E Iacob, Michael Przybylski
Alzheimer disease is a neurodegenerative disease affecting an increasing number of patients worldwide. Current therapeutic strategies are directed to molecules capable to block the aggregation of the β-amyloid(1-42) (Aβ) peptide and its shorter naturally occurring peptide fragments into toxic oligomers and amyloid fibrils. Aβ-specific antibodies have been recently developed as powerful antiaggregation tools. The identification and functional characterization of the epitope structures of Aβ antibodies contributes to the elucidation of their mechanism of action in the human organism...
January 2018: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/29320174/comprehensive-analysis-of-changes-in-crude-oil-chemical-composition-during-biosouring-and-treatments
#11
Jeremy A Nowak, Pravin Malla Shrestha, Robert Jay Weber, Amy M McKenna, Huan Chen, John D Coates, Allen H Goldstein
Biosouring in crude oil reservoirs by sulfate-reducing microbial communities (SRCs) results in hydrogen sulfide production, precipitation of metal sulfide complexes, increased industrial costs of petroleum production, and exposure issues for personnel. Potential treatment strategies include nitrate or perchlorate injections into reservoirs. Gas chromatography with vacuum ultraviolet ionization and high-resolution time-of-flight mass spectrometry (GC-VUV-HTOF) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) combined with electrospray ionization were applied in this study to identify hydrocarbon degradation patterns and product formations in crude oil samples from biosoured, nitrate treated, and perchlorate treated bioreactor column experiments...
January 10, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29320168/linking-natural-oil-seeps-from-the-gulf-of-mexico-to-their-origin-by-use-of-fourier-transform-ion-cyclotron-resonance-mass-spectrometry
#12
Logan C Krajewski, Vladislav V Lobodin, Caroline Johansen, Tessa E Bartges, Ekaterina V Maksimova, Ian R MacDonald, Alan G Marshall
We report chemical characterization of natural oil seeps from the Gulf of Mexico by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and Gas Chromatography/Atmospheric Pressure Chemical Ionization Mass Spectrometry (GC/APCI-MS), to highlight how FT-ICR MS can also be employed as a means to determine petroleum connectivity, in addition to traditional GC/MS techniques. The source of petroleum is the Green Canyon (GC) 600 lease block in the Gulf of Mexico. Within GC600, two natural oil seepage zones, Mega Plume and Birthday Candles, continuously release hydrocarbons and develop persistent oil slicks at the sea surface above them...
January 10, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29303558/21-tesla-ft-icr-mass-spectrometer-for-ultrahigh-resolution-analysis-of-complex-organic-mixtures
#13
Donald F Smith, David C Podgorski, Ryan P Rodgers, Greg T Blakney, Christopher L Hendrickson
We describe complex organic mixture analysis by 21 tesla (T) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ultrahigh mass-resolving power (m/Δm50% > 2 700 000 at m/z 400) and mass accuracy (80 ppb rms) enable resolution and confident identification of tens of thousands of unique elemental compositions. We demonstrate 2.2-fold higher mass-resolving power, 2.6-fold better mass measurement accuracy, and 1.3-fold more assigned molecular formulas compared to our custom-built, state-of-the-art 9...
January 5, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29301078/molecular-chemodiversity-of-dissolved-organic-matter-in-paddy-soils
#14
Xiaoming Li, Guo-Xin Sun, Songcan Chen, Zhi Fang, Hai-Yan Yuan, Quan Shi, Yong-Guan Zhu
Organic matter (OM), and dissolved organic matter (DOM), have a major influence upon biogeochemical processes; most significantly, the carbon cycle. To date, very few studies have examined the spatial heterogeneity of DOM in paddy soils. Thus, very little is known about the DOM molecular profiles and the key environmental factors that underpin DOM molecular chemodiversity in paddy soils. Here, Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) was applied to unambiguously resolve 11,361 molecular formulae in 16 paddy soils; thereby elucidating the molecular characteristics of paddy soil DOM...
January 4, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29300183/improved-proton-ct-imaging-using-a-bismuth-germanium-oxide-scintillator
#15
Sodai Tanaka, Teiji Nishio, Masato Tsuneda, Keiichiro Matsushita, Shigeto Kabuki, Mitsuru Uesaka
Range uncertainty is among the most formidable challenges associated with the treatment planning of proton therapy. Proton imaging, which includes proton radiography (pRG) and proton computed tomography (pCT), is a useful verification tool. We have developed a pCT detection system that uses a thick bismuth germanium oxide (BGO) scintillator and a CCD camera. The current method is based on a previous detection system that used a plastic scintillator, and implements improved image processing techniques. In the new system, the scintillation light intensity is integrated along the proton beam path by the BGO scintillator, and acquired as a two-dimensional distribution with the CCD camera...
January 4, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29297948/coalescence-and-self-bunching-observed-in-commercial-high-resolution-mass-spectrometry-instrumentation
#16
Anton Kaufmann, Stephan Walker
RATIONALE: Self-bunching and coalescence are well-known effects in Fourier transform ion cyclotron resonance (FTICR) and multi-reflection time-of-flight (TOF) mass spectrometry. These detrimental effects can also be observed in currently more frequently used high-resolution mass spectrometry (HRMS) instruments, such as the Orbitrap and single-reflection TOF. METHODS: A modern single-reflection TOF and a Q-Orbitrap were used to produce conditions in which self-bunching and coalescence were observed...
January 3, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29291493/89zr-for-antibody-labeling-and-in-vivo-studies-a-comparison-between-liquid-and-solid-target-production
#17
Gemma M Dias, Caterina F Ramogida, Julie Rousseau, Nicholas A Zacchia, Cornelia Hoehr, Paul Schaffer, Kuo-Shyan Lin, François Bénard
INTRODUCTION: Zirconium-89 (89Zr, t1/2=78.4h) liquid target (LT) production offers an approach to introduce this positron-emitting isotope to cyclotron centres without the need for a separate solid target (ST) production set up. We compared the production, purification, and antibody radiolabeling yields of 89Zr-(LT) and 89Zr-(ST), and assessed the feasibility of 89Zr-(LT) for preclinical PET/CT. METHODS: 89Zr-(ST) production was performed with an 89Y foil on a TR 19 cyclotron at 13...
November 16, 2017: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29289812/validating-production-of-pet-radionuclides-in-solid-and-liquid-targets-comparing-geant4-predictions-with-fluka-and-measurements
#18
T Amin, A Infantino, R Barlow, C Hoehr
The Monte Carlo toolkit Geant4 is used to simulate the production of a number of positron emitting radionuclides: 13N, 18F, 44Sc, 52Mn, 55Co 61Cu, 68Ga, 86Y, 89Zr and 94Tc, which have been produced using a 13MeV medical cyclotron. The results are compared to previous simulations with the Monte Carlo code FLUKA and experimental measurements. The comparison shows variable degrees of agreement for different isotopes. The mean absolute deviation of Monte Carlo results from experiments was 1.4±1.6 for FLUKA and 0...
December 21, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29289156/application-of-automatic-gain-control-for-radiometer-diagnostic-in-sst-1-tokamak
#19
Foram R Makwana, Varsha Siju, Praveenlal Edappala, S K Pathak
This paper describes the characterisation of a negative feedback type of automatic gain control (AGC) circuit that will be an integral part of the heterodyne radiometer system operating at a frequency range of 75-86 GHz at SST-1 tokamak. The developed AGC circuit is a combination of variable gain amplifier and log amplifier which provides both gain and attenuation typically up to 15 dB and 45 dB, respectively, at a fixed set point voltage and it has been explored for the first time in tokamak radiometry application...
December 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29286003/135la-as-an-auger-electron-emitter-for-targeted-internal-radiotherapy
#20
J Fonslet, B Q Lee, T A Tran, M Siragusa, M Jensen, T Kibédi, A E Stuchbery, G W Severin
135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, and dosimetry related to 135La therapy. 135La was produced by 16.5 MeV proton irradiation of metallic natBa on a medical cyclotron, and was isolated and purified by trap-and-release on weak cation-exchange resin. The average production rate was 407  ±  19 MBq µA-1 (saturation activity), and the radionuclidic purity was 98% at 20 h post irradiation...
December 29, 2017: Physics in Medicine and Biology
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