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https://www.readbyqxmd.com/read/28091630/accurate-measurement-of-long-range-proton-carbon-scalar-coupling-constants
#1
Claire L Dickson, Charles D Blundell, Craig P Butts, Alice Felton, Alex Jeffreys, Zoltan Takacs
The accuracy and practicality of measuring heteronuclear scalar coupling constants, (n)JCH, from modern NMR experimental methods is examined, based on F1 or F2 evolution of (n)JCH in HSQMBC (including EXSIDE) and HMBC experiments. The results from these methods are compared to both robust experimental data (derived from coupled (13)C spectra), computed (Density Functional Theory) and literature values where available. We report on the accuracy, ease of use and time efficiency of these multi-dimensional methods and highlight their extent and limitations...
January 16, 2017: Analyst
https://www.readbyqxmd.com/read/28088758/c5-substituents-of-uridines-and-2-thiouridines-present-at-the-wobble-position-of-trna-determine-the-formation-of-their-keto-enol-or-zwitterionic-forms-a-factor-important-for-accuracy-of-reading-of-guanosine-at-the-3-end-of-the-mrna-codons
#2
Elzbieta Sochacka, Elzbieta Lodyga-Chruscinska, Justyna Pawlak, Marek Cypryk, Paulina Bartos, Katarzyna Ebenryter-Olbinska, Grazyna Leszczynska, Barbara Nawrot
Modified nucleosides present in the wobble position of the tRNA anticodons regulate protein translation through tuning the reading of mRNA codons. Among 40 of such nucleosides, there are modified uridines containing either a sulfur atom at the C2 position and/or a substituent at the C5 position of the nucleobase ring. It is already evidenced that tRNAs with 2-thiouridines at the wobble position preferentially read NNA codons, while the reading mode of the NNG codons by R5U/R5S2U-containing anticodons is still elusive...
January 13, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28081526/phosphomolybdic-acid-and-ferric-iron-as-efficient-electron-mediators-for-coupling-biomass-pretreatment-to-produce-bioethanol-and-electricity-generation-from-wheat-straw
#3
Yi Ding, Bo Du, Xuebing Zhao, J Y Zhu, Dehua Liu
Phosphomolybdic acid (PMo12) was used as an electron mediator and proton carrier to mediate biomass pretreatment for ethanol production and electricity generation from wheat straw. In the pretreatment, lignin was oxidized anaerobically by PMo12 with solubilization of a fraction of hemicelluloses, and the PMo12 was simultaneously reduced. In an external liquid flow cell, the reduced PMo12 was re-oxidized with generation of electricity. The effects of several factors on pretreatment were investigated for optimizing the conditions...
January 3, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28081476/electron-spin-relaxation-of-a-boron-containing-heterocyclic-radical
#4
Sandra S Eaton, Kirby Huber, Hanan Elajaili, Joseph McPeak, Gareth R Eaton, Lauren E Longobardi, Douglas W Stephan
Preparation of the stable boron-containing heterocyclic phenanthrenedione radical, (C6F5)2B(O2C14H8), by frustrated Lewis pair chemistry has been reported recently. Electron paramagnetic resonance measurements of this radical were made at X-band in toluene:dichloromethane (9:1) from 10 to 293K, in toluene from 180 to 293K and at Q-band at 80K. In well-deoxygenated 0.1mM toluene solution at room temperature hyperfine splittings from (11)B, four pairs of (1)H, and 5 pairs of (19)F contribute to an EPR spectrum with many resolved lines...
December 30, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28079196/ultra-fast-charge-migration-competes-with-proton-transfer-in-the-early-chemistry-of-h2o%C3%AB
#5
Furong Wang, Uli Schmidhammer, Aurélien de La Lande, Mehran Mostafavi
Oxidation by the ultra-short lived radical cation of water, H2O˙(+), can potentially take place at the interface of water and numerous heterogeneous systems involved in radiation therapy, energy and environmental industries. The oxidation processes induced by H2O˙(+) can be mimicked in highly concentrated solutions where the nearest neighbors of H2O˙(+) may be molecules other than water. The reactivity of H2O˙(+) and D2O˙(+) is probed in hydrogenated and deuterated sulfuric acid solutions of various concentrations...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28076290/tailored-interactive-sequences-for-continuous-mr-image-guided-freehand-biopsies-of-different-organs-in-an-open-system-at-1-0-tesla-t-initial-experience
#6
Florian Streitparth, Christian Althoff, Martin Jonczyk, Felix Guettler, Martin Maurer, Hendrik Rathke, Keno Moritz Sponheuer, Bernd Hamm, Ulf K Teichgräber, Maximilian de Bucourt
OBJECTIVES: To assess the feasibility, image quality, and accuracy of freehand biopsies of liver, bone, muscle, vertebral disc, soft tissue, and other lesions using balanced steady-state free precession (SSFP, balanced fast field echo: bFFE), spoiled and nonspoiled gradient echo (FFE), and turbo spin echo (TSE) sequences for interactive continuous navigation in an open magnetic resonance imaging (MRI) system at 1.0 tesla (T). METHODS: Twenty-six MR-guided biopsies (five liver, five bone, four muscle, four vertebral disc, one lung, one kidney, one suprarenal gland, and five soft or other tissue) were performed in 23 patients in a 1...
January 11, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28075595/adsorption-of-small-cationic-nanoparticles-onto-large-anionic-particles-from-aqueous-solution-a-model-system-for-understanding-pigment-dispersion-and-the-problem-of-effective-particle-density
#7
Shannon M North, Elizabeth R Jones, Gregory N Smith, Oleksandr O Mykhaylyk, Tom Annable, Steven P Armes
This work focuses on the use of copolymer nanoparticles as a dispersant for a model pigment (silica). Reversible addition-fragmentation chain transfer (RAFT) alcoholic dispersion polymerization was used to synthesize sterically stabilized diblock copolymer nanoparticles. The steric stabilizer block was poly(2-dimethylamino)ethyl methacrylate) [PDMA] while the core-forming block was poly(benzyl methacrylate) [PBzMA]. The mean degrees of polymerization for the PDMA and PBzMA blocks were 71 and 100, respectively...
January 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28068377/a-theoretical-study-on-the-antioxidant-activity-of-piceatannol-and-isorhapontigenin-scavenging-nitric-oxide-and-nitrogen-dioxide-radicals
#8
Yang Lu, AiHua Wang, Peng Shi, Hui Zhang
The antioxidant activity of naturally occurring stilbene compounds piceatannol (PIC) and isorhapontigenin (ISO) scavenging two free radicals (NO and NO2) were studied using density functional theory (DFT) method. Four reaction mechanisms have been considered: hydrogen atom transfer (HAT), radical adduct formation (RAF), single electron transfer (SET), and sequential proton loss electron transfer (SPLET). The reaction channels in water solution were traced independently, and the respective thermodynamic and kinetic parameters were obtained...
2017: PloS One
https://www.readbyqxmd.com/read/28066887/the-effect-of-beam-purity-and-scanner-complexity-on-proton-ct-accuracy
#9
P Piersimoni, J Ramos-Méndez, T Geoghegan, V A Bashkirov, R W Schulte, B A Faddegon
PURPOSE: To determine the dependence of the accuracy in reconstruction of relative stopping power (RSP) with proton computerized tomography (pCT) scans on the purity of the proton beam and the technological complexity of the pCT scanner using standard phantoms and a digital representation of a pediatric patient. METHODS: The Monte Carlo method was applied to simulate the pCT scanner, using both a pure proton beam (uniform 200 MeV mono-energetic, parallel beam) and the Northwestern Medicine Chicago Proton Center (NMCPC) clinical beam in uniform scanning mode...
November 22, 2016: Medical Physics
https://www.readbyqxmd.com/read/28063601/bone-marrow-fat-content-is-correlated-with-hepatic-fat-content-in-paediatric-non-alcoholic-fatty-liver-disease
#10
N Y Yu, T Wolfson, M S Middleton, G Hamilton, A Gamst, J E Angeles, J B Schwimmer, C B Sirlin
AIM: To investigate the relationship between bone marrow fat content and hepatic fat content in children with known or suspected non-alcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: This was an institutional review board-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant, cross-sectional, prospective analysis of data collected between October 2010 to March 2013 in 125 children with known or suspected NAFLD. Written informed consent was obtained for same-day research magnetic resonance imaging (MRI) of the lumbar spine, liver, and abdominal adiposity...
January 4, 2017: Clinical Radiology
https://www.readbyqxmd.com/read/28060873/assessment-of-anterior-cingulate-cortex-acc-and-left-cerebellar-metabolism-in-asperger-s-syndrome-with-proton-magnetic-resonance-spectroscopy-mrs
#11
Aya Goji, Hiromichi Ito, Kenji Mori, Masafumi Harada, Sonoka Hisaoka, Yoshihiro Toda, Tatsuo Mori, Yoko Abe, Masahito Miyazaki, Shoji Kagami
PURPOSE: Proton magnetic resonance spectroscopy (1H MRS) is a noninvasive neuroimaging method to quantify biochemical metabolites in vivo and it can serve as a powerful tool to monitor neurobiochemical profiles in the brain. Asperger's syndrome (AS) is a type of autism spectrum disorder, which is characterized by impaired social skills and restrictive, repetitive patterns of interest and activities, while intellectual levels and language skills are relatively preserved. Despite clinical aspects have been well-characterized, neurometabolic profiling in the brain of AS remains to be clear...
2017: PloS One
https://www.readbyqxmd.com/read/28060512/solvent-dependent-dynamics-of-salicylidene-aniline-in-binary-mixtures-of-supercritical-co2-with-1-propanol-or-cyclohexane
#12
Ryan D Kieda, Adam D Dunkelberger, Amanda S Case, Forrest Fleming Crim
The role of different solvent environments in determining the behavior of molecules in solution is a fundamental aspect of chemical reactivity. We present an approach for exploring the influence of solvent properties on condensed-phase dynamics using ultrafast transient absorption spectroscopy in supercritical CO2. Using supercritical CO2 permits adjustment of the density, by varying the temperature and pressure, whereas varying the concentration or identity of a second solvent, the co-solvent, in a binary mixture allows for adjustments of the degree of interaction between the solute and the solvent...
January 6, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28060508/an-exploration-of-the-singlet-o2-oxidation-of-8-oxoguanine-by-guided-ion-beam-scattering-and-density-functional-theory-changes-of-reaction-intermediates-energetics-and-kinetics-upon-ionization-and-hydration
#13
Yan Sun, Wenchao Lu, Jianbo Liu
8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is one of the most common DNA lesions resulting from reactive oxygen species and ionizing radiation, and is involved in mutagenesis, carcinogenesis and cell death. Notably, 8-oxodGuo is more reactive toward singlet (a(1)Δg) O2 than the undamaged guanosine, and the lesions arising from the secondary oxidation of 8-oxodGuo are more mutagenic. Herein the (1)O2 oxidation of free base 8-oxoguanine (8-oxoG) was investigated at different initial conditions including protonated [8-oxoG + H](+), deprotonated [8-oxoG - H](-) and their monohydrates...
January 6, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28056391/proton-pump-inhibitors-on-pancreatic-cancer-risk-and-survival
#14
Malcolm D Kearns, Ben Boursi, Yu-Xiao Yang
BACKGROUND: Hypergastrinemia may promote the development and progression of pancreatic cancer. Proton pump inhibitor (PPI) therapy is known to cause hypergastrinemia. We sought to determine the association between PPI therapy and the risk of developing pancreatic cancer as well as survival following pancreatic cancer diagnosis. METHODS: We conducted a nested case-control study and a retrospective cohort study in The Health Improvement Network (THIN), a medical records database representative of the UK population...
January 2, 2017: Cancer Epidemiology
https://www.readbyqxmd.com/read/28054998/spectroscopic-dft-and-xrd-studies-of-hydrogen-bonds-in-n-unsubstituted-2-aminobenzamides
#15
Malose Jack Mphahlele, Marole Maria Maluleka, Lydia Rhyman, Ponnadurai Ramasami, Richard Mokome Mampa
The structures of the mono- and the dihalogenated N-unsubstituted 2-aminobenzamides were characterized by means of the spectroscopic (¹H-NMR, UV-Vis, FT-IR, and FT-Raman) and X-ray crystallographic techniques complemented with a density functional theory (DFT) method. The hindered rotation of the C(O)-NH₂ single bond resulted in non-equivalence of the amide protons and therefore two distinct resonances of different chemical shift values in the ¹H-NMR spectra of these compounds were observed. 2-Amino-5-bromobenzamide (ABB) as a model confirmed the presence of strong intramolecular hydrogen bonds between oxygen and the amine hydrogen...
January 4, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28054605/catalyst-support-effects-on-hydrogen-spillover
#16
Waiz Karim, Clelia Spreafico, Armin Kleibert, Jens Gobrecht, Joost VandeVondele, Yasin Ekinci, Jeroen A van Bokhoven
Hydrogen spillover is the surface migration of activated hydrogen atoms from a metal catalyst particle, on which they are generated, onto the catalyst support. The phenomenon has been much studied and its occurrence on reducible supports such as titanium oxide is established, yet questions remain about whether hydrogen spillover can take place on nonreducible supports such as aluminium oxide. Here we use the enhanced precision of top-down nanofabrication to prepare controlled and precisely tunable model systems that allow us to quantify the efficiency and spatial extent of hydrogen spillover on both reducible and nonreducible supports...
January 4, 2017: Nature
https://www.readbyqxmd.com/read/28050610/systematic-investigation-of-dft-giao-15-n-nmr-chemical-shift-prediction-using-b3lyp-cc-pvdz-application-to-studies-of-regioisomers-tautomers-protonation-states-and-n-oxides
#17
Dongyue Xin, Charles Avery Sader, Udo Fischer, Klaus Wagner, Paul-James Jones, Minli Xing, Keith R Fandrick, Nina C Gonnella
The calculation of (15)N NMR chemical shifts has been systematically investigated using density functional theory-gauge including/invariant atomic orbitals (DFT-GIAO) approximation at the B3LYP/cc-pVDZ level of theory. General linear regression terms for (15)N chemical shift predictions were calculated for nitromethane and liquid ammonia references in DMSO. Both aliphatic and aromatic nitrogens were studied using a diverse set of molecular scaffolds. Statistical error analysis between experiment and prediction revealed that, with the exception of primary amines, 95% of linear scaled N-15 chemical shifts are within a ±9...
January 4, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28048803/su-f-t-152-experimental-validation-and-calculation-benchmark-for-a-commercial-monte-carlo-pencil-beamscanning-proton-therapy-treatment-planning-system-in-heterogeneous-media
#18
L Lin, S Huang, M Kang, C Ainsley, C Simone, J McDonough, T Solberg
PURPOSE: Eclipse AcurosPT 13.7, the first commercial Monte Carlo pencil beam scanning (PBS) proton therapy treatment planning system (TPS), was experimentally validated for an IBA dedicated PBS nozzle in the CIRS 002LFC thoracic phantom. METHODS: A two-stage procedure involving the use of TOPAS 1.3 simulations was performed. First, Geant4-based TOPAS simulations in this phantom were experimentally validated for single and multi-spot profiles at several depths for 100, 115, 150, 180, 210 and 225 MeV proton beams, using the combination of a Lynx scintillation detector and a MatriXXPT ionization chamber array...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048802/tu-ab-brc-03-accurate-tissue-characterization-for-monte-carlo-dose-calculation-using-dual-and-multi-energy-ct-data
#19
A Lalonde, H Bouchard
PURPOSE: To develop a general method for human tissue characterization with dual-and multi-energy CT and evaluate its performance in determining elemental compositions and the associated proton stopping power relative to water (SPR) and photon mass absorption coefficients (EAC). METHODS: Principal component analysis is used to extract an optimal basis of virtual materials from a reference dataset of tissues. These principal components (PC) are used to perform two-material decomposition using simulated DECT data...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048781/su-f-t-141-proton-dose-validation-in-a-phantom-beyond-trufill-n-bca-embolization-glue
#20
A Mandapaka, A Ghebremedhin, B Patyal, Loma Linda
PURPOSE: To validate the treatment planning system predicted proton dose beyond a heterogeneity (n-BCA glue) by making a measurement in a custom acrylic phantom. METHODS: A custom cubic acrylic phantom was designed for this experiment. A container was designed to fit in the phantom. This container was filled with TRUFILL™ n-Butyl Cyanoacrylate(n-BCA) glue. When the container was placed in the phantom, its center was at a distance of 7.4cm from the entrance. This depth allows us to make measurements around the center of modulation of a 126 MeV proton beam with a 3cm spread-out-Bragg peak...
June 2016: Medical Physics
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