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C Schlosser, A Bollhöfer, S Schmid, R Krais, J Bieringer, M Konrad
Proportional counters and a β-γ coincidence system and their performance characteristics are described, with emphasis on internal and external quality controls. Typical limits of detection (LD) are 8mBqm(-3) for (85)Kr and 4mBqm(-3) for (133)Xe for the proportional counters, while for similar xenon volumes the LD for (133)Xe in the β-γ system is approximately 4 times lower. Results of comparative analyses agree above the limit of quantification. Xenon-133 levels in southern Germany are presently at or below the LD of the proportional counters, but above the LD of the β-γ system, which is now routinely used for analysis of environmental samples...
December 28, 2016: Applied Radiation and Isotopes
Troy Robinson, Nick Mann, Tracy Houghton, Matthew Watrous, John Peterson, Paul Fabian, Pat Hipp, Mark Reavis, Francisco Fernandez
INL has shown that a Marinelli beaker geometry can be used for the measurement of radioactive xenon in air using an aluminum Marinelli. A carbon fiber Marinelli was designed and constructed to improve overall performance. This composite Marinelli can withstand sample pressures of 276bar and achieve approximately a 4x performance improvement in the minimum detectable concentrations (MDCs) and concentration uncertainties. The MDCs obtained during a 24h assay for (133)Xe, (131m)Xe, and (135)Xe are: 1.4, 13, and 0...
January 4, 2017: Applied Radiation and Isotopes
Azeem Alam, Ka Chun Suen, Zac Hana, Robert D Sanders, Mervyn Maze, Daqing Ma
Growing and consistent preclinical evidence, combined with early clinical epidemiological observations, suggest potentially neurotoxic effects of commonly used anesthetic agents in the developing brain. This has prompted the FDA to issue a safety warning for all sedatives and anesthetics approved for use in children under three years of age. Recent studies have identified dexmedetomidine, the potent α2-adrenoceptor agonist, and xenon, the noble gas, as effective anesthetic adjuvants that are both less neurotoxic to the developing brain, and also possess neuroprotective properties in neonatal and other settings of acute ongoing neurologic injury...
January 5, 2017: Neurotoxicology and Teratology
Daan J L van Twist, Alfons J H M Houben, Michiel W de Haan, Peter W de Leeuw, Abraham A Kroon
BACKGROUND: Fibromuscular dysplasia (FMD) and atherosclerotic renal artery stenosis (ARAS) are the most common causes of renovascular hypertension. So far, FMD is believed to cause hypertension via similar mechanisms as in ARAS, that is, a decrease in renal blood flow, which subsequently leads to increased renin secretion. However, given the differences in the blood pressure (BP)-lowering effect of revascularization between patients with ARAS and FMD, we questioned whether this is true...
January 5, 2017: Journal of Hypertension
K Qing, J Mugler, Q Chen
PURPOSE: Hyperpolarized xenon-129 dissolved-phase MRI is the first imaging technique that allows 3-dimensional regional mapping of ventilation and gas uptake by tissue and blood the in human lung. Multiple outcome measures can be produced from this method. Existing studies in subjects with major lung diseases compared to healthy controls demonstrated high sensitivities of this method to pulmonary physiological factors including ventilation, alveolar tissue density, surface-to-volume ratio, pulmonary perfusion and gas-blood barrier thickness...
June 2016: Medical Physics
B Tahir, H Marshall, P Hughes, N Stewart, F Horn, G Collier, G Norquay, K Hart, J Swinscoe, M Hatton, J Wild, R Ireland
PURPOSE: To compare the spatial correlation of ventilation surrogates computed from inspiratory and expiratory breath-hold CT with hyperpolarized Helium-3 & Xenon-129 MRI in a cohort of lung cancer patients. METHODS: 5 patients underwent expiration & inspiration breath-hold CT. Xenon-129 & (1) H MRI were also acquired at the same inflation state as inspiratory CT. This was followed immediately by acquisition of Helium-3 & (1) H MRI in the same breath and at the same inflation state as inspiratory CT...
June 2016: Medical Physics
D Pinkham, M Negahdar, E Schueler, T Yamamoto, M Diehn, E Mittra, B Loo, P Maxim
PURPOSE: To demonstrate the efficacy of a novel functional lung imaging method that utilizes single-inhalation, single-energy xenon CT (Xe-CT) lung ventilation scans, and to compare it against the current clinical standard, ventilation single-photon emission CT (V-SPECT). METHODS: In an IRB-approved clinical study, 14 patients undergoing thoracic radiotherapy received two successive single inhalation, single energy (80keV) CT images of the entire lung using 100% oxygen and a 70%/30% xenon-oxygen mixture...
June 2016: Medical Physics
S Miyakawa, H Tachibana, S Moriya, T Kurosawa, M Sato
PURPOSE: A validation study using human or sheep for CT pulmonary ventilation (CT-V) imaging are inefficient and partially unstable. In this study, we designed and developed non-rigid phantom ventilating air to quantitatively evaluate the CT-V image. METHODS: The phantom consisted of an acryl cylinder filled with polyurethane foam designed to pulmonic alveoli and a polyurethane membrane was attached to the inferior end of the phantom to simulate a lung diaphragm...
June 2016: Medical Physics
Zhe Zhang, Haibin Tang, Zun Zhang, Joseph Wang, Shuai Cao
We present a new Retarding Potential Analyzer (RPA) design that is capable of measuring keV-level energy, high-density plasma beams. This instrument overcomes the limitations of existing RPAs and can operate in plasmas with densities in excess of 1 × 10(15) m(-3) and ion energies up to 1200 eV. The RPA design parameters were determined by analyzing the electron density and temperature, the sheath thickness, and the ion density in the beam based on the Faraday probe and Langmuir probe measurements. A previously unobserved grid spacing arcing phenomenon was observed in experiments...
December 2016: Review of Scientific Instruments
Monica Ciomaga Hatnean, Romain Sibille, Martin R Lees, Michel Kenzelmann, Voraksmy Ban, Vladimir Pomjakushin, Geetha Balakrishnan
Large single crystals of pyrochlore [Formula: see text] were successfully grown by the floating zone technique using an optical furnace equipped with high power xenon arc lamps. Structural investigations were carried out via powder synchrotron x-ray and neutron diffraction to establish the crystallographic structure of the materials produced. The magnetic properties of the single crystals were determined for magnetic fields applied along different crystallographic axes. The results revealed that [Formula: see text] is an interesting material for further investigation as a frustrated magnet...
February 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Joze Grdadolnik, Franci Merzel, Franc Avbelj
Hydrophobicity plays an important role in numerous physicochemical processes from the process of dissolution in water to protein folding, but its origin at the fundamental level is still unclear. The classical view of hydrophobic hydration is that, in the presence of a hydrophobic solute, water forms transient microscopic "icebergs" arising from strengthened water hydrogen bonding, but there is no experimental evidence for enhanced hydrogen bonding and/or icebergs in such solutions. Here, we have used the redshifts and line shapes of the isotopically decoupled IR oxygen-deuterium (O-D) stretching mode of HDO water near small purely hydrophobic solutes (methane, ethane, krypton, and xenon) to study hydrophobicity at the most fundamental level...
December 27, 2016: Proceedings of the National Academy of Sciences of the United States of America
Yoshiharu Ohno, Takeshi Yoshikawa, Daisuke Takenaka, Yasuko Fujisawa, Naoki Sugihara, Yuji Kishida, Shinichiro Seki, Hisanobu Koyama, Kazuro Sugimura
PURPOSE: To prospectively and directly compare the capability for assessments of regional ventilation and pulmonary functional loss in smokers of xenon-ventilation CT obtained with the dual-energy CT (DE-CT) and subtraction CT (Sub-CT) MATERIALS AND METHODS: Twenty-three consecutive smokers (15 men and 8 women, mean age: 69.7±8.7years) underwent prospective unenhanced and xenon-enhanced CTs, the latter by Sub-CT and DE-CT methods, ventilation SPECT and pulmonary function tests. Sub-CT was generated from unenhanced and xenon-enhanced CT, and all co-registered SPECT/CT data were produced from SPECT and unenhanced CT data...
January 2017: European Journal of Radiology
Weiwei Ruan, Jianping Zhong, Yu Guan, Yi Xia, Xiuchao Zhao, Yeqing Han, Xianping Sun, Shiyuan Liu, Chaohui Ye, Xin Zhou
PURPOSE: To demonstrate that hyperpolarized (HP) xenon diffusion kurtosis imaging (DKI) is able to detect smoke-induced pulmonary lesions in rat models. METHODS: Multi-b DKI with hyperpolarized xenon was used for the first time in five smoke-exposed rats and five healthy rats. Additionally, DKI with b values of up to 80 s/cm(2) were used in two healthy rats to probe the critical b value (a limit beyond which the DKI cannot describe the non-Gaussian diffusion). RESULTS: The mean apparent diffusion coefficient (Dapp ) and diffusion kurtosis (Kapp ) extracted by the DKI model revealed significant changes in the smoke-exposed rats compared with those in the control group (P = 0...
December 27, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
James T Goettel, Gary J Schrobilgen
The solid-state structure of xenon trioxide, XeO3, was reinvestigated by low-temperature single-crystal X-ray diffraction and shown to exhibit polymorphism that is dependent on the crystallization conditions. The previously reported α-phase (orthorhombic, P212121) only forms upon evaporation of aqueous HF solutions of XeO3. In contrast, two new phases, β-XeO3 (rhombohedral, R3) and γ-XeO3 (rhombohedral, R3c), have been obtained by slow evaporation of aqueous solutions of XeO3. The extended structures of all three phases result from Xe═O---Xe bridge interactions among XeO3 molecules that arise from the amphoteric donor-acceptor nature of XeO3...
December 19, 2016: Inorganic Chemistry
Zhumin Han, Xinyuan Wei, Chen Xu, Chi-Lun Chiang, Yanxing Zhang, Ruqian Wu, W Ho
The van der Waals interactions are responsible for a large diversity of structures and functions in chemistry, biology, and materials. Discussion of van der Waals interactions has focused on the attractive potential energy that varies as the inverse power of the distance between the two interacting partners. The origin of the attractive force is widely discussed as being due to the correlated fluctuations of electron charges that lead to instantaneous dipole-induced dipole attractions. Here, we use the inelastic tunneling probe to image the potential energy surface associated with the van der Waals interactions of xenon atoms...
December 15, 2016: Journal of Physical Chemistry Letters
K Niwa, F Matsuzaki, M Hasegawa
The van der Waals compound Xe(N2)2 with a C15 Laves structure was successfully synthesised at pressures greater than 4.4 GPa. We found that, at 10 GPa, the structure reversibly transforms from a cubic to a tetragonal phase. Further compression results in changes of Xe-N compound, which could result in the enhancement of orbital interactions between the xenon and nitrogen atoms.
December 21, 2016: Physical Chemistry Chemical Physics: PCCP
John R Cormack, Jarrod Gott, Sarah Kondogiannis
No abstract text is available yet for this article.
December 9, 2016: A & A Case Reports
Christian Stoppe, Julia Ney, Rolf Rossaint, Mark Coburn, Andreas Goetzenich
No abstract text is available yet for this article.
December 9, 2016: Sports Medicine
Chun-De Liao, Jau-Yih Tsauo, Tsan-Hon Liou, Hung-Chou Chen, Chi-Lun Rau
BACKGROUND: Stellate ganglion blockade (SGB) is mainly used to relieve symptoms of neuropathic pain in conditions such as complex regional pain syndrome and has several potential complications. Noninvasive SGB performed using physical agent modalities (PAMs), such as light irradiation and electrical stimulation, can be clinically used as an alternative to conventional invasive SGB. However, its application protocols vary and its clinical efficacy remains controversial. This study investigated the use of noninvasive SGB for managing neuropathic pain or other disorders associated with sympathetic hyperactivity...
2016: PloS One
Drew Elliott, Earl Scime, Zachary Short
Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration...
November 2016: Review of Scientific Instruments
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