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R Muñoz, C Munuera, J I Martínez, J Azpeitia, C Gómez-Aleixandre, M García-Hernández
Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650°C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω·sq(-1)...
March 2017: 2d Mater
G Timothy Noe, Ikufumi Katayama, Fumiya Katsutani, James J Allred, Jeffrey A Horowitz, David M Sullivan, Qi Zhang, Fumiya Sekiguchi, Gary L Woods, Matthias C Hoffmann, Hiroyuki Nojiri, Jun Takeda, Junichiro Kono
We have developed a single-shot terahertz time-domain spectrometer to perform optical-pump/terahertz-probe experiments in pulsed, high magnetic fields up to 30 T. The single-shot detection scheme for measuring a terahertz waveform incorporates a reflective echelon to create time-delayed beamlets across the intensity profile of the optical gate beam before it spatially and temporally overlaps with the terahertz radiation in a ZnTe detection crystal. After imaging the gate beam onto a camera, we can retrieve the terahertz time-domain waveform by analyzing the resulting image...
December 26, 2016: Optics Express
Sung-Gun Park, Gordon A Anderson, James E Bruce
FT-based high performance mass analyzers yield increased resolving power and mass measurement accuracy, yet require increased duration of signal acquisition that can limit many applications. The implementation of stronger magnetic fields, multiple detection electrodes for harmonic signal detection, and an array of multiple mass analyzers arranged along the magnetic field axis have been used to decrease required acquisition time. The results presented here show that multiple ion cyclotron resonance (ICR) mass analyzers can also be implemented orthogonal to the central magnetic field axis...
January 5, 2017: Journal of the American Society for Mass Spectrometry
Mathilde Farenc, Matthias Witt, Kirsten Craven, Caroline Barrère-Mangote, Carlos Afonso, Pierre Giusti
Polyolefins such as polyethylene (PE) and polypropylene (PP) are often characterized from their pyrolysis products by Py-MS. Nowadays the development of plasma-based direct probe atmospheric pressure sources allow the direct analysis of these polymers. These sources operate at atmospheric pressure, which implies a limited control of the ionization conditions. It was shown that side reactions could occur with species present in air, such as O2, which may lead to the formation of oxidized compounds. In this work, ion mobility-mass spectrometry (IM-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR) were used for the exhaustive characterization of the PP and PE pyrolysis ions produced using plasma-based atmospheric pressure ion sources...
January 3, 2017: Journal of the American Society for Mass Spectrometry
K C Jones, F Vander Stappen, C M Sehgal, S Avery
PURPOSE: To determine the accuracy and dose required for acoustic-based proton range verification (protoacoustics) in water. METHODS: Proton pulses with 17 µs FWHM and instantaneous currents of 480 nA (5.6 × 10(7) protons/pulse, 8.9 cGy/pulse) were generated by a clinical, hospital-based cyclotron at the University of Pennsylvania. The protoacoustic signal generated in a water phantom by the 190 MeV proton pulses was measured with a hydrophone placed at multiple known positions surrounding the dose deposition...
June 2016: Medical Physics
J Wulff, E Abel
PURPOSE: Introducing Monte Carlo based dose calculation algorithms into proton therapy planning systems (TPS) leads to improved accuracy. However accurate modelling of the proton pencil beam impinging the patient is necessary. Current approaches rely on measurement-driven reconstruction of phase-space and spectrum properties, typically constrained to analytical model functions. In this study a detailed Monte Carlo model of the complete cyclotron-based delivery system was created with the aim of providing more representative beam properties at treatment position...
June 2016: Medical Physics
S Patch, M Kireeff Covo, A Jackson, Y Qadadha, K Campbell, R Albright, P Bloemhard, A Donoghue, C Siero, T Gimpel, S Small, B Ninemire, M Johnson, L Phair
PURPOSE: The potential of particle therapy has not yet been fully realized due to inaccuracies in range verification. The purpose of this work was to correlate the Bragg peak location with target structure, by overlaying thermoacoustic localization of the Bragg peak onto an ultrasound image. METHODS: Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the inflector of the 88″ cyclotron at Lawrence Berkeley National Lab...
June 2016: Medical Physics
Y John Zhai
PURPOSE: To obtain an improved precise gamma efficiency calibration curve of HPGe (High Purity Germanium) detector with a new comprehensive approach. METHODS: Both of radioactive sources and Monte Carlo simulation (CYLTRAN) are used to determine HPGe gamma efficiency for energy range of 0-8 MeV. The HPGe is a GMX coaxial 280 cm(3) N-type 70% gamma detector. Using Momentum Achromat Recoil Spectrometer (MARS) at the K500 superconducting cyclotron of Texas A&M University, the radioactive nucleus (24) Al was produced and separated...
June 2016: Medical Physics
J Verburg, T Bortfeld
PURPOSE: We present a new system to perform prompt gamma-ray spectroscopy during proton pencil-beam scanning treatments, which enables in vivo verification of the proton range. This system will be used for the first clinical studies of this technology. METHODS: After successful pre-clinical testing of prompt gamma-ray spectroscopy, a full scale system for clinical studies is now being assembled. Prompt gamma-rays will be detected during patient treatment using an array of 8 detector modules arranged behind a tungsten collimator...
June 2016: Medical Physics
C Kim, J Seduk, T Yang
PURPOSE: A prototype actives scanning beam delivery system was designed, manufactured and installed as a part of the Korea Heavy Ion Medical Accelerator Project. The prototype system includes the most components for steering, modulating, detecting incident beam to patient. The system was installed in MC-50 cyclotron beam line and tested to extract the normal operation conditions. METHODS: The commissioning process was completed by using 45 MeV of proton beam. To measure the beam position accuracy along the scanning magnet power supply current, 25 different spots were scanning and measured...
June 2016: Medical Physics
S Graves, R Hernandez, C England, H Valdovinos, J Jeffery, T Barnhart, W Cai, R Nickles
PURPOSE: To image β-cells noninvasively using radio-manganese PET and to develop efficient small cyclotron production of (51) Mn (t1/2=46m, β(+) =97%) and (52) Mn (t1/2=5.6d, β(+) =29%). METHODS: (51) Mn and (52) Mn were produced by 16 MeV proton irradiation (GE PETtrace) of electrodeposited (54) Fe on silver and Cr metal pressed into a silver disc, respectively. (51) Mn was radiochemically isolated from target material by anion exchange chromatography and (52) Mn was isolated by ethanolic anion exchange trap-and-release...
June 2016: Medical Physics
S Tanaka, T Nishio, K Matsushita, M Tsuneda, S Kabuki, M Uesaka
PURPOSE: In the treatment planning of proton therapy, Water Equivalent Length (WEL), which is the parameter for the calculation of dose and the range of proton, is derived by X-ray CT (xCT) image and xCT-WEL conversion. However, about a few percent error in the accuracy of proton range calculation through this conversion has been reported. The purpose of this study is to construct a proton CT (pCT) imaging system for an evaluation of the error. METHODS: The pCT imaging system was constructed with a thick scintillator and a cooled CCD camera, which acquires the two-dimensional image of integrated value of the scintillation light toward the beam direction...
June 2016: Medical Physics
Tetsuya Goto, Kei-Ichiro Sato, Yuki Yabuta, Shigetoshi Sugawa
A mirror-field confined compact electron cyclotron resonance (ECR) plasma source using permanent magnets was developed, aiming for the realization of high-quality plasma processings where high-density reactive species are supplied to a substrate with minimizing the ion bombardment damages. The ECR position was located between a microwave transmissive window and a quartz limiter, and plasmas were transported from the ECR position to a midplane of the magnetic mirror field through the quartz limiter. Thus, a radius of core plasma could be determined by the limiter, which was 15 mm in this study...
December 2016: Review of Scientific Instruments
Yinming Shao, Kirk W Post, Jhih-Sheng Wu, Siyuan Dai, Alex James Frenzel, Anthony R Richardella, Joon Sue Lee, Nitin Samarth, Michael M Fogler, Alexander V Balatsky, Dmitri E Kharzeev, Dimitri N Basov
Using magneto-infrared spectroscopy, we have explored the charge dynamics of (Bi,Sb)2Te3 thin films on InP substrates. From the magneto-transmission data we extracted three distinct cyclotron resonance (CR) energies that are all apparent in the broad band Faraday rotation (FR) spectra. This comprehensive FR-CR data set has allowed us to isolate the response of the bulk states from the intrinsic surface states associated with both the top and bottom surfaces of the film. The FR data uncovered that electron- and hole-type Dirac fermions reside on opposite surfaces of our films, which paves the way for observing many exotic quantum phenomena in topological insulators...
December 29, 2016: Nano Letters
Jesper Fonslet, Sabrina Tietze, Andreas I Jensen, Stephen A Graves, Gregory W Severin
Pressed chromium-powder cyclotron targets were irradiated with 16MeV protons, producing (52)Mn with average yields of 6.2±0.8MBq/µAh. Separation by solid-phase anion exchange from ethanol-HCl mixtures recovered 94.3±1.7% of (52)Mn and reduced the chromium content by a factor of 2.2±0.4×10(5). An additional AG 1-X8 column was used to remove copper, iron, cobalt and zinc impurities from the prepared (52)Mn in 8M HCl. The macrocyclic chelator DOTA was rapidly radiolabeled with (52)Mn in aq. ammonium acetate (pH 7...
December 21, 2016: Applied Radiation and Isotopes
Xiaodong Wang, Jun Han, Darryl B Hardie, Juncong Yang, Jingxi Pan, Christoph H Borchers
In this work, we combined the use of two MALDI matrices (quercetin and 9-aminoacridine), a recently developed new matrix coating technique - matrix coating assisted by an electric field (MCAEF), and matrix-assisted laser desorption/ionization - Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICRMS) to detect and image endogenous compounds in the cancerous and non-cancerous regions of three human prostate cancer (stage II) tissue specimens. After three rounds of imaging data acquisitions (i...
December 23, 2016: Biochimica et Biophysica Acta
Feng Li, Chun-Hua Huang, Lin-Na Xie, Na Qu, Jie Shao, Bo Shao, Ben-Zhan Zhu
N-hydroxyphthalimide (NHPI), which is best known as an organocatalyst for efficient C-H activation, has been found to be oxidized by quinoid compounds to its corresponding catalytically active nitroxide-radical. Here, we found that NHPI can be isomerized into isatoic anhydride by an unusually facile two-step method using tetrachloro-1,4-benzoquinone (TCBQ, p-chloranil), accompanied by a two-step hydrolytic dechlorination of highly toxic TCBQ into the much less toxic dihydroxylation product, 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid)...
December 23, 2016: Scientific Reports
Sandra L Blair, Amanda C MacMillan, Greg T Drozd, Allen H Goldstein, Rosalie K Chu, Ljiljana Paša-Tolić, Jared B Shaw, Nikola Tolić, Peng Lin, Julia Laskin, Alexander Laskin, Sergey A Nizkorodov
Secondary organic aerosol (SOA), formed in the photooxidation of diesel fuel, biodiesel fuel, and 20% biodiesel fuel/80% diesel fuel mixture, are prepared under high-NOx conditions in the presence and absence of sulfur dioxide (SO2), ammonia (NH3), and relative humidity (RH). The composition of condensed-phase organic compounds in SOA is measured using several complementary techniques including aerosol mass spectrometry (AMS), high-resolution nanospray desorption electrospray ionization mass spectrometry (nano-DESI/HRMS), and ultrahigh resolution and mass accuracy 21T Fourier transform ion cyclotron resonance mass spectrometry (21T FT-ICR MS)...
January 3, 2017: Environmental Science & Technology
Annamaria Croce, Ezio Battistel, Stefano Chiaberge, Silvia Spera, Francesco De Angelis, Samantha Reale
Binary and ternary mixtures of cellulose, bovine serum albumin (BSA) and tripalmitin, as biomass reference compounds for carbohydrates, proteins and triglycerides, respectively, were treated under hydrothermal liquefaction (HTL) conditions to describe the main reaction pathways involved in the process of bio-oil production from municipal organic wastes. Several analytical techniques (elemental analysis, GC-MS, atmospheric-pressure photo-ionisation high-resolution Fourier transform ion cyclotron resonance mass spectrometry, and (13) C cross-polarisation magic-angle spinning NMR spectroscopy) were used for the molecular-level characterisation of the resulting aqueous phase, solid residue and bio-oil, in particular...
December 22, 2016: ChemSusChem
Daniel J Karst, Robert Steinhoff, Marie R G Kopp, Elisa Serra, Miroslav Soos, Renato Zenobi, Massimo Morbidelli
Perfusion cell culture processes allow the steady-state culture of mammalian cells at high viable cell density, which is beneficial for overall product yields and homogeneity of product quality in the manufacturing of therapeutic proteins. In this study, the extent of metabolic steady state and the change of the metabolite profile between different steady states of an industrial Chinese hamster ovary (CHO) cell line producing a monoclonal antibody (mAb) was investigated in stirred tank perfusion bioreactors...
December 20, 2016: Biotechnology Progress
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