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https://www.readbyqxmd.com/read/27913106/innovations-in-radiotherapy-technology
#1
I J Feain, L Court, J R Palta, S Beddar, P Keall
Many low- and middle-income countries, together with remote and low socioeconomic populations within high-income countries, lack the resources and services to deal with cancer. The challenges in upgrading or introducing the necessary services are enormous, from screening and diagnosis to radiotherapy planning/treatment and quality assurance. There are severe shortages not only in equipment, but also in the capacity to train, recruit and retain staff as well as in their ongoing professional development via effective international peer-review and collaboration...
November 29, 2016: Clinical Oncology: a Journal of the Royal College of Radiologists
https://www.readbyqxmd.com/read/27911881/low-energy-ne-ion-beam-induced-modifications-of-magnetic-properties-in-mnas-thin-films
#2
M Trassinelli, L Bernard Carlsson, S Cervera, M Eddrief, V H Etgens, E V Gafton, E Lacaze, E Lamour, A Lévy, S Macé, C Prigent, J-P Rozet, S Steydli, M Marangolo, D Vernhet
Investigations of the complex behavior of the magnetization of manganese arsenide thin films due to defects induced by irradiation of slow heavy ions are presented. In addition to the thermal hysteresis suppression already highlighted in Trassinelli et al (2014 Appl. Phys. Lett. 104 081906), we report here on new local magnetic features recorded by a magnetic force microscope at different temperatures close to the characteristic sample phase transition. Complementary measurements of the global magnetization in different conditions (applied magnetic field and temperatures) enable the film characterization to be completed...
December 2, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/27911417/plasma-assisted-molecular-beam-epitaxy-of-n-polar-inaln-barrier-high-electron-mobility-transistors
#3
Matthew T Hardy, David F Storm, D Scott Katzer, Brian P Downey, Neeraj Nepal, David J Meyer
Plasma-assisted molecular beam epitaxy is well suited for the epitaxial growth of III-nitride thin films and heterostructures with smooth, abrupt interfaces required for high-quality high-electron-mobility transistors (HEMTs). A procedure is presented for the growth of N-polar InAlN HEMTs, including wafer preparation and growth of buffer layers, the InAlN barrier layer, AlN and GaN interlayers and the GaN channel. Critical issues at each step of the process are identified, such as avoiding Ga accumulation in the GaN buffer, the role of temperature on InAlN compositional homogeneity, and the use of Ga flux during the AlN interlayer and the interrupt prior to GaN channel growth...
November 24, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27910643/quasi-optical-design-for-systems-to-diagnose-the-electron-temperature-and-density-fluctuations-on-east
#4
Qifo Cao, Yong Liu, Hailin Zhao, Tianfu Zhou, Ang Ti, Liqun Hu
A system to simultaneously diagnose the electron temperature and density fluctuations is proposed for Experimental Advanced Superconducting Tokamak device. This system includes a common quasi-optical antenna, a correlation electron cyclotron emission (CECE) system that is used to measure the electron temperature fluctuations and a Doppler backscattering (DBS) system that is used to measure the electron density fluctuations. The frequency range of the proposed CECE system is 108-120 GHz, and this corresponds to a radial coverage of normalized radius ((R - R0)/a, R0 = 1850 mm, a = 450 mm) from 0...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910582/experimentally-determining-the-relative-efficiency-of-spherically-bent-germanium-and-quartz-crystals
#5
G V Brown, P Beiersdorfer, N Hell, E Magee
We have used the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory and a duplicate Orion High Resolution X-ray Spectrometer (OHREX) to measure the relative efficiency of a spherically bent quartz (101̄1) crystal (2d = 6.687 Å) and a spherically bent germanium (111) crystal (2d = 6.532 Å). L-shell X-ray photons from highly charged molybdenum ions generated in EBIT-I were simultaneously focussed and Bragg reflected by each crystal, both housed in a single spectrometer, onto a single CCD X-ray detector...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910570/imaging-crystal-spectrometer-for-high-resolution-x-ray-measurements-on-electron-beam-ion-traps-and-tokamaks
#6
P Beiersdorfer, E W Magee, N Hell, G V Brown
We describe a crystal spectrometer implemented on the Livermore electron beam ion traps that employ two spherically bent quartz crystals and a cryogenically cooled back-illuminated charge-coupled device detector to measure x rays with a nominal resolving power of λ/Δλ ≥ 10 000. Its focusing properties allow us to record x rays either with the plane of dispersion perpendicular or parallel to the electron beam and, thus, to preferentially select one of the two linear x-ray polarization components. Moreover, by choice of dispersion plane and focussing conditions, we use the instrument either to image the distribution of the ions within the 2 cm long trap region, or to concentrate x rays of a given energy to a point on the detector, which optimizes the signal-to-noise ratio...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910569/l-shell-spectroscopic-diagnostics-of-radiation-from-krypton-hed-plasma-sources
#7
E E Petkov, A S Safronova, V L Kantsyrev, V V Shlyaptseva, R S Rawat, K S Tan, P Beiersdorfer, N Hell, G V Brown
X-ray spectroscopy is a useful tool for diagnosing plasma sources due to its non-invasive nature. One such source is the dense plasma focus (DPF). Recent interest has developed to demonstrate its potential application as a soft x-ray source. We present the first spectroscopic studies of krypton high energy density plasmas produced on a 3 kJ DPF device in Singapore. In order to diagnose spectral features, and to obtain a more comprehensive understanding of plasma parameters, a new non-local thermodynamic equilibrium L-shell kinetic model for krypton was developed...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910505/characterization-of-an-atomic-hydrogen-source-for-charge-exchange-experiments
#8
M A Leutenegger, P Beiersdorfer, G L Betancourt-Martinez, G V Brown, N Hell, R L Kelley, C A Kilbourne, E W Magee, F S Porter
We characterized the dissociation fraction of a thermal dissociation atomic hydrogen source by injecting the mixed atomic and molecular output of the source into an electron beam ion trap containing highly charged ions and recording the x-ray spectrum generated by charge exchange using a high-resolution x-ray calorimeter spectrometer. We exploit the fact that the charge exchange state-selective capture cross sections are very different for atomic and molecular hydrogen incident on the same ions, enabling a clear spectroscopic diagnostic of the neutral species...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910475/ion-gyroscale-fluctuation-measurement-with-microwave-imaging-reflectometer-on-kstar
#9
W Lee, J Leem, G S Yun, H K Park, S H Ko, W X Wang, R V Budny, N C Luhmann, K W Kim
Ion gyroscale turbulent fluctuations with the poloidal wavenumber kθ ∼ 3 cm(-1) have been measured in the core region of the neutral beam (NB) injected low confinement (L-mode) plasmas on Korea superconducting tokamak advanced research. The turbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame, measured by the multichannel microwave imaging reflectometer. Linear and nonlinear gyrokinetic simulations also predict the unstable modes with the normalized wavenumber kθρs ∼ 0...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910385/advances-in-the-ftu-collective-thomson-scattering-system
#10
W Bin, A Bruschi, O D'Arcangelo, G Grosso, L Lubiako, E Alessi, C Castaldo, C Centioli, M De Angeli, L Figini, C Galperti, S Garavaglia, G Granucci, M Lontano, S Magagnino, V Mellera, D Minelli, A Moro, A Muraro, A Nardone, F Orsitto, A Simonetto, U Tartari
The new collective Thomson scattering diagnostic installed on the Frascati Tokamak Upgrade device started its first operations in 2014. The ongoing experiments investigate the presence of signals synchronous with rotating tearing mode islands, possibly due to parametric decay processes, and phenomena affecting electron cyclotron beam absorption or scattering measurements. The radiometric system, diagnostic layout, and data acquisition system were improved accordingly. The present status and near-term developments of the diagnostic are presented...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910382/fast-imaging-diagnostics-on-the-c-2u-advanced-beam-driven-field-reversed-configuration-device
#11
E M Granstedt, P Petrov, K Knapp, M Cordero, V Patel
The C-2U device employed neutral beam injection, end-biasing, and various particle fueling techniques to sustain a Field-Reversed Configuration (FRC) plasma. As part of the diagnostic suite, two fast imaging instruments with radial and nearly axial plasma views were developed using a common camera platform. To achieve the necessary viewing geometry, imaging lenses were mounted behind re-entrant viewports attached to welded bellows. During gettering, the vacuum optics were retracted and isolated behind a gate valve permitting their removal if cleaning was necessary...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910351/calibration-of-the-ohrex-high-resolution-imaging-crystal-spectrometer-at-the-livermore-electron-beam-ion-traps
#12
N Hell, P Beiersdorfer, E W Magee, G V Brown
We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27908179/an-evaluation-of-spatial-resolution-of-a-prototype-proton-ct-scanner
#13
Tia E Plautz, V Bashkirov, V Giacometti, R F Hurley, R P Johnson, P Piersimoni, H F-W Sadrozinski, R W Schulte, A Zatserklyaniy
PURPOSE: To evaluate the spatial resolution of proton CT using both a prototype proton CT scanner and Monte Carlo simulations. METHODS: A custom cylindrical edge phantom containing twelve tissue-equivalent inserts with four different compositions at varying radial displacements from the axis of rotation was developed for measuring the modulation transfer function (MTF) of a prototype proton CT scanner. Two scans of the phantom, centered on the axis of rotation, were obtained with a 200 MeV, low-intensity proton beam: one scan with steps of 4°, and one scan with the phantom continuously rotating...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27903405/separation-of-44-ti-from-proton-irradiated-scandium-by-using-solid-phase-extraction-chromatography-and-design-of-44-ti-44-sc-generator-system
#14
V Radchenko, C A L Meyer, J W Engle, C M Naranjo, G A Unc, T Mastren, M Brugh, E R Birnbaum, K D John, F M Nortier, M E Fassbender
Scandium-44g (half-life 3.97h [1]) shows promise for positron emission tomography (PET) imaging of longer biological processes than that of the current gold standard, (18)F, due to its favorable decay parameters. One source of (44g)Sc is the long-lived parent nuclide (44)Ti (half-life 60.0 a). A (44)Ti/(44g)Sc generator would have the ability to provide radionuclidically pure (44g)Sc on a daily basis. The production of (44)Ti via the (45)Sc(p,2n) reaction requires high proton beam currents and long irradiation times...
November 24, 2016: Journal of Chromatography. A
https://www.readbyqxmd.com/read/27886506/measurement-of-excitation-spectra-in-the-12-c-p-d-reaction-near-the-%C3%AE-emission-threshold
#15
Y K Tanaka, K Itahashi, H Fujioka, Y Ayyad, J Benlliure, K-T Brinkmann, S Friedrich, H Geissel, J Gellanki, C Guo, E Gutz, E Haettner, M N Harakeh, R S Hayano, Y Higashi, S Hirenzaki, C Hornung, Y Igarashi, N Ikeno, M Iwasaki, D Jido, N Kalantar-Nayestanaki, R Kanungo, R Knöbel, N Kurz, V Metag, I Mukha, T Nagae, H Nagahiro, M Nanova, T Nishi, H J Ong, S Pietri, A Prochazka, C Rappold, M P Reiter, J L Rodríguez-Sánchez, C Scheidenberger, H Simon, B Sitar, P Strmen, B Sun, K Suzuki, I Szarka, M Takechi, I Tanihata, S Terashima, Y N Watanabe, H Weick, E Widmann, J S Winfield, X Xu, H Yamakami, J Zhao
Excitation spectra of ^{11}C are measured in the ^{12}C(p,d) reaction near the η^{'} emission threshold. A proton beam extracted from the synchrotron SIS-18 at GSI with an incident energy of 2.5 GeV impinges on a carbon target. The momenta of deuterons emitted at 0° are precisely measured with the fragment separator (FRS) operated as a spectrometer. In contrast to theoretical predictions on the possible existence of deeply bound η^{'}-mesic states in carbon nuclei, no distinct structures are observed associated with the formation of bound states...
November 11, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27880736/experimental-validation-of-a-multi-energy-x-ray-adapted-scatter-separation-method
#16
A Sossin, V Rebuffel, J Tabary, J M Létang, N Freud, L Verger
Both in radiography and computed tomography (CT), recently emerged energy-resolved x-ray photon counting detectors enable the identification and quantification of individual materials comprising the inspected object. However, the approaches used for these operations require highly accurate x-ray images. The accuracy of the images is severely compromised by the presence of scattered radiation, which leads to a loss of spatial contrast and, more importantly, a bias in radiographic material imaging and artefacts in CT...
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27869865/multipass-optical-system-for-a-raman-gas-spectrometer
#17
Dmitry V Petrov
In the present work, a multipass optical system intended for increasing the sensitivity of a Raman gas spectrometer based on the 90° geometry of scattered light collection is described. The system is characterized by an adjustment stability and an increased number of laser beams that pass through a small scattering volume, thus allowing the intensities of Raman signals from components of the gas medium in this volume to be increased. It is demonstrated that the application of this multipass optical system allows the sensitivity of the Raman gas spectrometer to be increased practically by 20 times (to several ppm for the 30-s registration time)...
November 20, 2016: Applied Optics
https://www.readbyqxmd.com/read/27869823/high-resolution-three-dimensional-structural-microscopy-by-single-angle-bragg-ptychography
#18
S O Hruszkewycz, M Allain, M V Holt, C E Murray, J R Holt, P H Fuoss, V Chamard
Coherent X-ray microscopy by phase retrieval of Bragg diffraction intensities enables lattice distortions within a crystal to be imaged at nanometre-scale spatial resolutions in three dimensions. While this capability can be used to resolve structure-property relationships at the nanoscale under working conditions, strict data measurement requirements can limit the application of current approaches. Here, we introduce an efficient method of imaging three-dimensional (3D) nanoscale lattice behaviour and strain fields in crystalline materials with a methodology that we call 3D Bragg projection ptychography (3DBPP)...
November 21, 2016: Nature Materials
https://www.readbyqxmd.com/read/27869644/hydrogen-gas-sensors-from-polysilicon-nanobelt-devices-selectively-modified-with-sensing-materials
#19
Nhan Ai Tran, Fu-Ming Pan, Jeng-Tzong Sheu
Double-junction n(+)/n(-)/n(+) polysilicon nanobelts featuring selectively deposited sensing materials have been investigated for application as H2 gas sensors. The selective modification of the devices was performed through a combination of localized ablation of a resist and lift-off of a previous catalyst material deposited through e-beam evaporation. Four nanobelt devices, differentiated by their doping concentrations at the n(-) region (from 2.5 × 10(13) to 2.5 × 10(14) cm(-2)), were analyzed in terms of the responses to H2 and their self-heating effects...
December 16, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27867425/gold-nanoparticles-for-cancer-radiotherapy-a-review
#20
REVIEW
Kaspar Haume, Soraia Rosa, Sophie Grellet, Małgorzata A Śmiałek, Karl T Butterworth, Andrey V Solov'yov, Kevin M Prise, Jon Golding, Nigel J Mason
Radiotherapy is currently used in around 50% of cancer treatments and relies on the deposition of energy directly into tumour tissue. Although it is generally effective, some of the deposited energy can adversely affect healthy tissue outside the tumour volume, especially in the case of photon radiation (gamma and X-rays). Improved radiotherapy outcomes can be achieved by employing ion beams due to the characteristic energy deposition curve which culminates in a localised, high radiation dose (in form of a Bragg peak)...
2016: Cancer Nanotechnology
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