نتایج جستجو برای: proton shift

تعداد نتایج: 201000  

2016
Todd M. Alam Zuolei Liao May Nyman Jonathan Yates

Solid-state H magic-angle spinning (MAS) NMR was used to investigate local proton environments in anhydrous [UO2(OH)2] (α-UOH) and hydrated uranyl hydroxide [(UO2)4O(OH)6·5H2O (metaschoepite). For the metaschoepite material, proton resonances of the μ2-OH hydroxyl and interlayer waters were resolved, with twodimensional (2D) double-quantum (DQ) H−H NMR correlation experiments revealing strong d...

Journal: :Magnetic resonance in medicine 2006
Pierre-Gilles Henry Malgorzata Marjanska Jamie D Walls Julien Valette Rolf Gruetter Kâmil Ugurbil

Proton-observed carbon-edited (POCE) NMR spectroscopy is commonly used to measure 13C labeling with higher sensitivity compared to direct 13C NMR spectroscopy, at the expense of spectral resolution. For weakly coupled first-order spin systems, the multiplet signal at a specific proton chemical shift in POCE spectra directly reflects 13C enrichment of the carbon attached to this proton. The pres...

Journal: :Chemical communications 2010
Yongqian Xu Yi Pang

A bis(benzoxazole) derivative with metal-chelating ligand (DPA), Zinhbo-1, exhibits a large fluorescence turn-on effect (up to 10-fold) upon zinc-binding. The metal chelation enables excited state intramolecular proton transfer (ESIPT), giving an additional emission band in the near-IR region (approximately 710 nm) with a large Stokes shift (ca. 230 nm).

1999
Krzysztof Pachucki

The proton structure effects, including finite size, polarizability and self– energy is considered and their influence on energy levels of muonic hydrogen is recalculated. A new theoretical prediction for the Lamb shift is presented together with improved values of all known QED contributions. PACS numbers 36.10 Dr, 12.20 Ds, 31.30 Jv Typeset using REVTEX E-mail address: [email protected]

Journal: :Physical review letters 2011
Richard J Hill Gil Paz

Proton structure effects in hydrogenic bound states are analyzed using nonrelativistic QED effective field theory. Implications for the Lamb shift in muonic hydrogen are discussed. Model-dependent assumptions in previous analyses are isolated, and sensitivity to poorly constrained hadronic structure in the two-photon exchange contribution is identified.

ژورنال: سنجش و ایمنی پرتو 2014

In this study, the MCNPX code version 2.6 has been used to simulate a proton therapy in thyroid gland. The neck phantom is cylindrical including skin, adipose, skeletal muscle and thyroid gland. Radiation source is close to the skin surface and single energy protons are collided perpendicular to the skin surface. The results of the simulation shows that the best proton energy interval, to cover...

Journal: :Journal of the American Chemical Society 2010
Malek Nechab Damien Campolo Julien Maury Patricia Perfetti Nicolas Vanthuyne Didier Siri Michèle P Bertrand

The cascade rearrangement of chiral enediynes 1c-e, involving successively 1,3-proton shift, Saito-Myers cyclization, 1,5-hydrogen atom transfer, and intramolecular coupling of the resulting biradical, proceeded at 80 °C to form tri- and tetracyclic heterocycles possessing a quaternary stereogenic center with a very high level of memory of chirality.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1973
B L Hawkins J D Roberts

Carbon-13 nuclear magnetic resonance spectra have been taken of Delta(8)- and Delta(9)-tetrahydrocannabinol. The absorptions have been assigned to specific carbons with the aid of off-resonance and selective proton-decoupling experiments, as well as by chemical-shift comparison with model compounds.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2008
Prasad Phatak Nilanjan Ghosh Haibo Yu Qiang Cui Marcus Elstner

The positions of protons are not available in most high-resolution structural data of biomolecules, thus the identity of proton storage sites in biomolecules that transport proton is generally difficult to determine unambiguously. Using combined quantum mechanical/molecular mechanical computations, we demonstrate that a pair of conserved glutamate residues (Glu 194/204) bonded by a delocalized ...

Journal: :iranian journal of medical physics 0
alireza karimian department of biomedical engineering, faculty of engineering, university of isfahan, isfahan, iran.

introduction proton therapy is used to treat malignant tumors such as melanoma inside the eye. proton particles are adjusted according to various parameters such as tumor size and position and patient’s distance from the proton source. the purpose of this study was to assess absorbed doses in eyes and various tumors found in the area of sclera and choroid and the adjacent tissues in radiotherap...

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