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https://www.readbyqxmd.com/read/28634405/shedding-new-light-on-an-old-molecule-quinophthalone-displays-uncommon-n-to-o-excited-state-intramolecular-proton-transfer-esipt-between-photobases
#1
Gi Rim Han, Doyk Hwang, Seunghoon Lee, Jong Woo Lee, Eunhak Lim, Jiyoung Heo, Seong Keun Kim
Excited state dynamics of common yellow dye quinophthalone (QPH) was probed by femtosecond transient absorption spectroscopy. Multi-exponential decay of the excited state and significant change of rate constants upon deuterium substitution indicate that uncommon nitrogen-to-oxygen excited state intramolecular proton transfer (ESIPT) occurs. By performing density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, we found that adiabatic surface crossing between the S1 and S2 states takes place in the photoreaction...
June 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28633524/charge-migration-in-eyring-walter-and-kimball-s-1944-model-of-the-electronically-excited-hydrogen-molecule-ion
#2
Dennis J Diestler, Gunter Hermann, Jörn Manz
In an elementary variational treatment of the electronic structure of H2+ Eyring, Walter and Kimball (EWK) serendipitously discovered charge migration (CM) in 1944. Using an analytic expression for the electronic probability density (EPD), they found that if the electron is initially localized on one of the protons (by taking the initial state to be a superposition of the ground and first-excited electronic energy eigenstates), then it oscillates adiabatically between fixed protons with a period T inversely proportional to the energy gap between the eigenstates...
June 21, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28630929/splitting-of-the-o-o-bond-at-the-heme-copper-catalytic-site-of-respiratory-oxidases
#3
Federica Poiana, Christoph von Ballmoos, Nathalie Gonska, Margareta R A Blomberg, Pia Ädelroth, Peter Brzezinski
Heme-copper oxidases catalyze the four-electron reduction of O2 to H2O at a catalytic site that is composed of a heme group, a copper ion (CuB), and a tyrosine residue. Results from earlier experimental studies have shown that the O-O bond is cleaved simultaneously with electron transfer from a low-spin heme (heme a/b), forming a ferryl state (PR ; Fe(4+)=O(2-), CuB(2+)-OH(-)). We show that with the Thermus thermophilus ba3 oxidase, at low temperature (10°C, pH 7), electron transfer from the low-spin heme b to the catalytic site is faster by a factor of ~10 (τ ≅ 11 μs) than the formation of the PR ferryl (τ ≅110 μs), which indicates that O2 is reduced before the splitting of the O-O bond...
June 2017: Science Advances
https://www.readbyqxmd.com/read/28628033/nonalcoholic-fatty-liver-disease-with-cirrhosis-increases-familial-risk-for-advanced-fibrosis
#4
Cyrielle Caussy, Meera Soni, Jeffrey Cui, Ricki Bettencourt, Nicholas Schork, Chi-Hua Chen, Mahdi Al Ikhwan, Shirin Bassirian, Sandra Cepin, Monica P Gonzalez, Michel Mendler, Yuko Kono, Irine Vodkin, Kristin Mekeel, Jeffrey Haldorson, Alan Hemming, Barbara Andrews, Joanie Salotti, Lisa Richards, David A Brenner, Claude B Sirlin, Rohit Loomba
BACKGROUND: The risk of advanced fibrosis in first-degree relatives of patients with nonalcoholic fatty liver disease and cirrhosis (NAFLD-cirrhosis) is unknown and needs to be systematically quantified. We aimed to prospectively assess the risk of advanced fibrosis in first-degree relatives of probands with NAFLD-cirrhosis. METHODS: This is a cross-sectional analysis of a prospective cohort of 26 probands with NAFLD-cirrhosis and 39 first-degree relatives. The control population included 69 community-dwelling twin, sib-sib, or parent-offspring pairs (n = 138), comprising 69 individuals randomly ascertained to be without evidence of NAFLD and 69 of their first-degree relatives...
June 19, 2017: Journal of Clinical Investigation
https://www.readbyqxmd.com/read/28627542/gas-phase-vibrational-spectroscopy-of-triphenylamine-the-effect-of-charge-on-structure-and-spectra
#5
Musleh Uddin Munshi, Giel Berden, Jonathan Martens, Jos Oomens
The effect of ionization by oxidation and protonation on the structure and IR spectrum of isolated, gas-phase triphenylamine (TPA) has been investigated by infrared multiple photon dissociation (IRMPD) spectroscopy in the fingerprint range from 600 cm(-1) to 1800 cm(-1) using an infrared free electron laser. IR spectra calculated using density functional theory (DFT) convincingly reproduce the experimental data. Spectral and structural differences are identified among neutral TPA, TPA˙(+) and protonated TPA and qualitatively related to effects of resonance delocalization...
June 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28626099/-a-cross-sectional-study-on-the-correlation-between-mri-signal-for-ipfp-and-knee-osteoarthritis
#6
Song Wu, Hongliang Ba, Jinshen He, Yunjie Liao
To investigate the correlation between MRI signal for infrapatellar fat pad (IPFP) and pathological changes in knee osteoarthritis (KOA), and to analyze the role of IPFP in the development of knee osteoarthritis.
 Methods: A total of 114 subjects (without special knee disease) were enrolled for this study. The intensity of MRI signal for IPFP was determined by fat-suppressed proton-density-weighted turbospin-echo magnetic resonance imaging. Based on the cartilage defects and osteophytes of knee joint, the subjects were divided into a KOA group and a control group...
May 28, 2017: Zhong Nan da Xue Xue Bao. Yi Xue Ban, Journal of Central South University. Medical Sciences
https://www.readbyqxmd.com/read/28624986/temperature-corrected-post-mortem-1-5%C3%A2-t-mri-quantification-of-non-pathologic-upper-abdominal-organs
#7
Nicole Schwendener, Christian Jackowski, Frederick Schuster, Anders Persson, Marcel J Warntjes, Wolf -Dieter Zech
OBJECTIVES: The present study aimed to evaluate if simultaneous temperature-corrected T1, T2, and proton density (PD) 1.5 T post-mortem MR quantification [quantitative post-mortem magnetic resonance imaging (QPMMRI)] is feasible for characterizing and discerning non-pathologic upper abdominal organs (liver, spleen, pancreas, kidney) with regard to varying body temperatures. METHODS: QPMMRI was performed on 80 corpses (25 females, 55 males; mean age 56.2 years, SD 17...
June 17, 2017: International Journal of Legal Medicine
https://www.readbyqxmd.com/read/28624865/bone-marrow-fat-contributes-to-insulin-sensitivity-and-adiponectin-secretion-in-premenopausal-women
#8
Federica Ermetici, Silvia Briganti, Alessandra Delnevo, Paola Cannaò, Giovanni Di Leo, Stefano Benedini, Ileana Terruzzi, Francesco Sardanelli, Livio Luzi
PURPOSE: Bone marrow fat is a functionally distinct adipose tissue that may contribute to systemic metabolism. This study aimed at evaluating a possible association between bone marrow fat and insulin sensitivity indices. METHODS: Fifty obese (n = 23) and non-obese (n = 27) premenopausal women underwent proton magnetic resonance spectroscopy to measure vertebral bone marrow fat content and unsaturation index at L4 level. Abdominal visceral, subcutaneous fat, and epicardial fat were also measured using magnetic resonance imaging...
June 17, 2017: Endocrine
https://www.readbyqxmd.com/read/28624576/agreement-between-magnetic-resonance-imaging-proton-density-fat-fraction-measurements-and-pathologist-assigned-steatosis-grades-of-liver-biopsies-from-adults-with-nonalcoholic-steatohepatitis
#9
Michael S Middleton, Elhamy R Heba, Catherine A Hooker, Mustafa R Bashir, Kathryn J Fowler, Kumar Sandrasegaran, Elizabeth M Brunt, David E Kleiner, Edward Doo, Mark L Van Natta, James Tonascia, Joel E Lavine, Brent A Neuschwander-Tetri, Arun Sanyal, Rohit Loomba, Claude B Sirlin
BACKGROUND & AIMS: We assessed the diagnostic performance of magnetic resonance imaging (MRI) proton density fat fraction (PDFF) in grading hepatic steatosis and change in hepatic steatosis in adults with nonalcoholic steatohepatitis (NASH) in a multi-center study, using central histology as reference. METHODS: We collected data from 113 adults with NASH participating in a multi-center, randomized, double-masked, placebo-controlled, phase 2b trial to compare the efficacy cross-sectionally and longitudinally of obeticholic acid vs placebo...
June 14, 2017: Gastroenterology
https://www.readbyqxmd.com/read/28620719/large-coverage-mr-neurography-in-cidp-diagnostic-accuracy-and-electrophysiological-correlation
#10
Moritz Kronlage, Philipp Bäumer, Kalliopi Pitarokoili, Daniel Schwarz, Véronique Schwehr, Tim Godel, Sabine Heiland, Ralf Gold, Martin Bendszus, Min-Suk Yoon
The objective of this study was to evaluate large coverage magnetic resonance neurography (MRN) in chronic inflammatory demyelinating polyneuropathy (CIDP). In this prospective study, 18 patients with CIDP and 18 healthy controls were examined by a standardized MRN protocol at 3 T. Lumbosacral plexus was imaged by a T2-weighted 3D sequence and peripheral nerves of the upper and lower extremity by axial T2-weighted turbo spin-echo sequences. Lesions were characterized by nerve cross-sectional area (CSA) and T2-weighted signal (nT2)...
June 15, 2017: Journal of Neurology
https://www.readbyqxmd.com/read/28612206/temperature-corrected-postmortem-3-t-mr-quantification-of-histopathological-early-acute-and-chronic-myocardial-infarction-a-feasibility-study
#11
Anders Persson, John Baeckmann, Johan Berge, Christian Jackowski, Marcel Warntjes, Wolf-Dieter Zech
The goal of the present study was to evaluate if quantitative postmortem cardiac 3-T magnetic resonance (QPMCMR) T1 and T2 relaxation times and proton density values of histopathological early acute and chronic myocardial infarction differ to the quantitative values of non-pathologic myocardium and other histopathological age stages of myocardial infarction with regard to varying corpse temperatures. In 60 forensic corpses (25 female, 35 male), a cardiac 3-T MR quantification sequence was performed prior to autopsy and cardiac dissection...
June 13, 2017: International Journal of Legal Medicine
https://www.readbyqxmd.com/read/28609604/highly-stable-low-gas-cross-over-proton-conducting-phenylated-polyphenylenes
#12
Michael Adamski, Thomas J G Skalski, Benjamin Britton, Timothy J Peckham, Lukas Metzler, Steven Holdcroft
Two classes of novel sulfonated phenylated polyphenylene ionomers are investigated as polyaromatic-based proton exchange membranes. Both types of ionomer possess high ion exchange capacities yet are insoluble in water at elevated temperatures. They exhibit high proton conductivity under both fully hydrated conditions and reduced relative humidity, and are markedly resilient to free radical attack. Fuel cells constructed with membrane-electrode-assemblies containing each ionomer membrane yield high in situ proton conductivity and peak power densities that are greater than obtained using Nafion reference membranes...
June 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28609097/computational-study-of-h2s-release-in-reactions-of-diallyl-polysulfides-with-thiols
#13
You-Ru Cai, Ching-Han Hu
Hydrogen sulfide (H2S) is a gasotransmitter molecule recognized for its role in cell signaling. Garlic-derived polysulfides including diallyl disulfide (DADS) and diallyl trisulfide (DATS) have been shown to release H2S. We investigated the mechanism of the reaction of DADS and DATS with biological thiols, including cysteine (Cys) and glutathione (GSH) using density functional theory. We propose that Cys and GSH react with DADS and DATS in their anionic forms. Thiol anions are much more likely to attack the sulfur atoms of DADS and DATS than the α-carbon of allyl groups...
June 13, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28605195/flexible-and-lightweight-fuel-cell-with-high-specific-power-density
#14
Fandi Ning, Xudong He, Yangbin Shen, Hehua Jin, Qingwen Li, Da Li, Shuping Li, Yulu Zhan, Ying Du, Jingjing Jiang, Hui Yang, Xiaochun Zhou
Flexible devices have been attracting great attention recently due to their numerous advantages. But the energy densities of current energy sources are still not high enough to support flexible devices for a satisfactory length of time. Although proton exchange membrane fuel cells (PEMFCs) do have a high-energy density, traditional PEMFCs are usually too heavy, rigid, and bulky to be used in flexible devices. In this research, we successfully invented a light and flexible air-breathing PEMFC by using a new design of PEMFC and a flexible composite electrode...
June 12, 2017: ACS Nano
https://www.readbyqxmd.com/read/28600521/application-of-sodium-ion-based-solid-electrolyte-in-electrostatic-tuning-of-carrier-density-in-graphene
#15
Jialin Zhao, Meng Wang, Xuefu Zhang, Yue Lv, Tianru Wu, Shan Qiao, Shufeng Song, Bo Gao
Using a solid electrolyte to tune the carrier density in thin-film materials is an emerging technique that has potential applications in both basic and applied research. Until now, only materials containing small ions, such as protons and lithium ions, have been used to demonstrate the gating effect. Here, we report the study of a lab-synthesised sodium-ion-based solid electrolyte, which shows a much stronger capability to tune the carrier density in graphene than previously reported lithium-ion-based solid electrolyte...
June 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28599920/a-self-recirculation-electrolyte-system-for-unbuffered-microbial-fuel-cells-with-an-aerated-cathode
#16
Liang Zhang, Xun Zhu, Jun Li, Qian Fu, Qiang Liao, Yan Li, Yuanxin Li
A self-recirculation electrolyte system driven by air bubble buoyancy force is proposed for unbuffered microbial fuel cells (MFC) in this study. It was demonstrated that the electrolyte recirculation rate increased with the aeration rate in a certain range. Compared with buffer condition, buffer-less condition resulted in a 10%∼20% lower voltage (14.2% lower maximum power density) but a 9.1% higher Coulombic efficiency (CE) at an aeration rate of 92.0ml/min. Under buffer-less condition, increasing the aeration rate resulted in a higher voltage output, a higher COD removal, and a higher CE due to the enhanced proton transfer and increased oxygen for cathode reaction...
May 31, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28597944/a-quantum-mechanical-study-of-the-binding-pocket-of-proteorhodopsin-absorption-and-vibrational-spectra-modulated-by-analogue-chromophores
#17
Francesco Buda, Tom Keijer, Srividya Ganapathy, Willem J de Grip
Proteorhodopsin is a light-driven proton pumping membrane protein related to bacteriorhodopsin. It contains an all-trans retinal A1 chromophore covalently bound to a lysine residue via a protonated Schiff base. In this study, we exploited density functional theory (DFT) calculations to investigate the retinal binding pocket in the dark state and after mimicking photoisomerization. The model of the binding pocket is constructed incrementally by adding the residues near the retinal that are necessary to ensure a stable protonated Schiff base...
June 9, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28594557/long-lived-13-c2-nuclear-spin-states-hyperpolarized-by-parahydrogen-in-reversible-exchange-at-micro-tesla-fields
#18
Zijian Zhou, Jin Yu, Johannes F P Colell, Raul Laasner, Angus W J Logan, Danila A Barskiy, Roman V Shchepin, Eduard Y Chekmenev, Volker Blum, Warren S Warren, Thomas Theis
Parahydrogen is an inexpensive and readily available source of hyperpolarization used to enhance magnetic resonance signals by up to 4 orders of magnitude above thermal signals obtained at ~10 T. A significant challenge for applications is fast signal decay after hyperpolarization. Here, we use parahydrogen based polarization transfer catalysis at micro-Tesla fields (first introduced as SABRE-SHEATH) to hyperpolarize (13)C2 spin pairs and find decay time constants of 12 s for magnetization at 0.3 mT, which are extended to 2 minutes at that same field, when long lived singlet states are hyperpolarized instead...
June 8, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28590468/the-influence-of-cation-ordering-oxygen-vacancy-distribution-and-proton-siting-on-observed-properties-in-ceramic-electrolytes-the-case-of-scandium-substituted-barium-titanate
#19
Nico Torino, Paul F Henry, Christopher S Knee, Tor Svendsen Bjørheim, Seikh M H Rahman, Emma Suard, Carlotta Giacobbe, Sten G Eriksson
The origin of the 2-order of magnitude difference in the proton conductivity of the hydrated forms of hexagonal and cubic oxygen deficient BaScxTi1-xO3-δ (x = 0.2 and x = 0.7) was probed using a combination of neutron diffraction and density functional theory techniques to support published X-ray diffraction, conductivity, thermogravimetric and differential scanning calorimetry studies. Cation ordering is found in the 6H structure type (space group P63/mmc) adopted by BaSc0.2Ti0.8O3-δ with scandium preferentially substituting in the vertex sharing octahedra (2a crystallographic site) and avoiding the face-sharing octahedra (4f site)...
June 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28589660/simultaneous-quantification-of-bone-edema-adiposity-and-structure-in-inflamed-bone-using-chemical-shift-encoded-mri-in-spondyloarthritis
#20
Timothy J P Bray, Alan Bainbridge, Shonit Punwani, Yiannis Ioannou, Margaret A Hall-Craggs
PURPOSE: To evaluate proton density fat fraction (PDFF) and R2* as markers of bone marrow composition and structure in inflamed bone in patients with spondyloarthritis. METHODS: Phantoms containing fat, water, and trabecular bone were constructed with proton density fat fraction (PDFF) and bone mineral density (BMD) values matching those expected in healthy bone marrow and disease states, and scanned using chemical shift-encoded MRI (CSE-MRI) at 3T. Measured PDFF and R2* values in phantoms were compared with reference FF and BMD values...
June 6, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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