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Hilla P, Vaara J. NMR chemical shift of confined 129Xe: coordination number, paramagnetic channels and molecular dynamics in a cryptophane-A biosensor. Phys Chem Chem Phys 2023; 25:22719-22733. [PMID: 37606522 DOI: 10.1039/d3cp02695g] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Advances in hyperpolarisation and indirect detection have enabled the development of xenon nuclear magnetic resonance (NMR) biosensors (XBSs) for molecule-selective sensing in down to picomolar concentration. Cryptophanes (Crs) are popular cages for hosting the Xe "spy". Understanding the microscopic host-guest chemistry has remained a challenge in the XBS field. While early NMR computations of XBSs did not consider the important effects of host dynamics and explicit solvent, here we model the motionally averaged, relativistic NMR chemical shift (CS) of free Xe, Xe in a prototypic CrA cage and Xe in a water-soluble CrA derivative, each in an explicit H2O solvent, over system configurations generated at three different levels of molecular dynamics (MD) simulations. We confirm the "contact-type" character of the Xe CS, arising from the increased availability of paramagnetic channels, magnetic couplings between occupied and virtual orbitals through the short-ranged orbital hyperfine operator, when neighbouring atoms are in contact with Xe. Remarkably, the Xe CS in the present, highly dynamic and conformationally flexible situations is found to depend linearly on the coordination number of the Xe atom. We interpret the high- and low-CS situations in terms of the magnetic absorption spectrum and choose our preference among the used MD methods based on comparison with the experimental CS. We check the role of spin-orbit coupling by comparing with fully relativistic CS calculations. The study outlines the computational workflow required to realistically model the CS of Xe confined in dynamic cavity structures under experimental conditions, and contributes to microscopic understanding of XBSs.
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Affiliation(s)
- Perttu Hilla
- NMR Research Unit, P.O. Box 3000, FI-90014 University of Oulu, Finland.
| | - Juha Vaara
- NMR Research Unit, P.O. Box 3000, FI-90014 University of Oulu, Finland.
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Zanini A, Fasolo F, Visca L, Durisi E, Perosino M, Annand JRM, Burn KW. Test of a bubble passive spectrometer for neutron dosimetry. Phys Med Biol 2005; 50:4287-97. [PMID: 16148394 DOI: 10.1088/0031-9155/50/18/004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A passive system for neutron spectrometry has been tested in view of neutron dose evaluation in mixed radiation fields. This system, based on bubble detectors (Bubble Technology Industries, Ontario, Canada), is suitable to evaluate the neutron energy distribution in the range 10 keV-20 MeV even in the presence of intense gamma radiation, as required in various fields: medical x-ray accelerators, nuclear reactors, cosmic ray exposures on commercial high-altitude flights and space missions. A new unfolding code BUNTO has been especially developed for this application. In the present work, the results of two experimental tests are summarized. In the first one, the device has been exposed to a standard AmBe neutron source (Joint Research Centre, Ispra, Varese, Italy). In the second one, measurements have been carried out at the MAX-Lab photonuclear facility in Sweden, with a bremsstrahlung photon beam impinging on thick targets of different materials and generating a giant dipole resonance neutron spectrum. Simulations of the experimental apparatus have been performed with MCNP4B (AmBe source) and with MCNP4B-GN (MAX-Lab). Results of the comparison between experimental and calculated spectra are shown and discussed. A good agreement between measurements and simulation data is obtained in both the experiments.
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Affiliation(s)
- A Zanini
- INFN Sez. Torino, V P Giuria 1, 10125 Torino, Italy.
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Abstract
Total absorption cross-sections of hydrogen, carbon, copper, silver, lead and uranium have been measured for photons of mean energy 94 MeV. The method was to measure the transmission through an absorber of photons from the Oxford synchrotron, using a biased liquid scintillation counter to select photons of energy near the peak energy of the machine. The experimental data for hydrogen have been used to deduce a value for the cross-section for pair production in the field of the electron of 4.7 ± 0.4 millibarn. The relative cross-sections for the heavier elements have been determined to better than ± 0.2 %, and confirm the most recent calculations of the correction to the Born approximation in the theory of pair production.
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Delorme J, Ericson M, Ericson T, Vogel P. Pion and neutron production by cosmic-ray muons underground. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1995; 52:2222-2230. [PMID: 9970738 DOI: 10.1103/physrevc.52.2222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Kaushal NN, Winhold EJ, Yergin PF, Medicus HA, Augustson RH. Fast-Photoneutron Spectra due to 55-85-MeV Photons. ACTA ACUST UNITED AC 1968. [DOI: 10.1103/physrev.175.1330] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Alsmiller R, Moran H. Photoneutron production from 34- and 100-MeV electrons in thick uranium targets. ACTA ACUST UNITED AC 1967. [DOI: 10.1016/0029-554x(67)90024-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Alsmiller R, Moran H. Electron-photon cascade calculations and neutron yields from electrons in thick targets. ACTA ACUST UNITED AC 1967. [DOI: 10.1016/0029-554x(67)90469-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Fultz SC, Bramblett RL, Caldwell JT, Harvey RR. Photoneutron Cross Sections for Natural Cu,Cu63, andCu65. ACTA ACUST UNITED AC 1964. [DOI: 10.1103/physrev.133.b1149] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Goldemberg J, Torizuka Y, Barber W, Walecka J. Excitation of the electric dipole giant resonance by inelastic electron scattering at 180°. ACTA ACUST UNITED AC 1963. [DOI: 10.1016/0029-5582(63)90345-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bonazzola G, Borello O, Costa S, Ferroni S. Photodisintegration of sulphur in the 30–80 MeV range. ACTA ACUST UNITED AC 1962. [DOI: 10.1016/0029-5582(62)90013-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Emma V, Milone C, Rubbino A. Energy Spectra and Angular Distribution of Photoneutrons from Carbon. ACTA ACUST UNITED AC 1960. [DOI: 10.1103/physrev.118.1297] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Barber WC, George WD, Reagan DD. Absolute Cross Section for the ReactionC12(γ, n)C11. ACTA ACUST UNITED AC 1955. [DOI: 10.1103/physrev.98.73] [Citation(s) in RCA: 84] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Halpern I, Debs RJ, Eisinger JT, Fairhall AW, Richter HG. Yields of Photonuclear Reactions with 320-Mev X-Rays. II. Interpretation of Results. ACTA ACUST UNITED AC 1955. [DOI: 10.1103/physrev.97.1327] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Nathans R, Halpern J. Excitation Function for the Photodisintegration of Beryllium. ACTA ACUST UNITED AC 1953. [DOI: 10.1103/physrev.92.940] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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