An imaging method called "quantification of relaxation times and proton density by twin-echo saturation-recovery turbo-field echo" (QRAPTEST) is presented as a means of quickly determining the longitudinal T(1) and transverse T(2) (*) relaxation time and proton density (PD) within a single sequence. The method also includes an estimation of the B(1) field inhomogeneity. High-resolution images covering large volumes can be achieved within clinically acceptable times of 5-10 min. The range of accuracy for determining T(1), T(2) (*), and PD values is flexible and can be optimized relative to any anticipated values. We validated the experimental results against existing methods, and provide a clinical example in which quantification of the whole brain using 1.5 mm(3) voxels was achieved in less than 8 min.
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http://dx.doi.org/10.1002/mrm.21165 | DOI Listing |
Magn Reson Med
January 2025
Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
Purpose: Pulmonary MRI faces challenges due to low proton density, rapid transverse magnetization decay, and cardiac and respiratory motion. The fermat-looped orthogonally encoded trajectories (FLORET) sequence addresses these issues with high sampling efficiency, strong signal, and motion robustness, but has not yet been applied to phase-resolved functional lung (PREFUL) MRI-a contrast-free method for assessing pulmonary ventilation during free breathing. This study aims to develop a reconstruction pipeline for FLORET UTE, enhancing spatial resolution for three-dimensional (3D) PREFUL ventilation analysis.
View Article and Find Full Text PDFNat Commun
January 2025
WA School of Mines: Minerals, Energy and Chemical Engineering (WASM-MECE), Curtin University, Perth, WA, 6102, Australia.
Reducing green hydrogen production cost is critical for its widespread application. Proton-exchange-membrane water electrolyzers are among the most promising technologies, and significant research has been focused on developing more active, durable, and cost-effective catalysts to replace expensive iridium in the anode. Ruthenium oxide is a leading alternative while its stability is inadequate.
View Article and Find Full Text PDFAdv Mater
January 2025
Shenzhen Key Laboratory of Energy Electrocatalytic Materials, Guangdong Provincial Key Laboratory of New Energy Materials Service Safety, College of Materials Science and Engineering, Shenzhen University, Shenzhen, Guangdong, 518055, P. R. China.
Engineering nanomaterials at single-atomic sites can enable unprecedented catalytic properties for broad applications, yet it remains challenging to do so on RuO-based electrocatalysts for proton exchange membrane water electrolyzer (PEMWE). Herein, the rational design and construction of Bi-RuO single-atom alloy oxide (SAAO) are presented to boost acidic oxygen evolution reaction (OER), via phase engineering a novel hexagonal close packed (hcp) RuBi single-atom alloy. This Bi-RuO SAAO electrocatalyst exhibits a low overpotential of 192 mV and superb stability over 650 h at 10 mA cm, enabling a practical PEMWE that needs only 1.
View Article and Find Full Text PDFChemistry
January 2025
University of Oxford, Inorganic Chemistry Laboratory, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
Combining experiment and theory, the mechanisms of H2 activation by the potassium-bridged aluminyl dimer K2[Al(NON)]2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tertbutyl-9,9-dimethylxanthene) and its monomeric K+-sequestered counterpart have been investigated. These systems show diverging reactivity towards the activation of dihydrogen, with the dimeric species undergoing formal oxidative addition of H2 at each Al centre under ambient conditions, and the monomer proving to be inert to dihydrogen addition. Noting that this K+ dependence is inconsistent with classical models of single-centre reactivity for carbene-like Al(I) species, we rationalize these observations instead by a cooperative frustrated Lewis pair (FLP)-type mechanism (for the dimer) in which the aluminium centre acts as the Lewis base and the K+ centres as Lewis acids.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Key Laboratory of Soft Chemistry and Functional Materials of MOE, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
2-(2-Hydroxyphenyl)benzothiazole (HBT) derivatives with donor-π-acceptor (D-π-A) structure have received extensive attention as a class of excited state intramolecular proton transfer (ESIPT) compounds in the fields of biochemistry and photochemistry. The effects of electron-donors (triphenylamine and anthracenyl), the position of substituents and solvent polarity on the fluorescence properties and ESIPT mechanisms of HBT derivatives were investigated through time-dependent density functional theory (TDDFT) calculations. Potential energy curves (PECs) and frontier molecular orbitals (FMOs) reveal that the introduction of the triphenylamine group on the benzene ring enhances intramolecular HB, thereby benefiting the ESIPT process.
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