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Jiacheng Yi, Hua Fang
The effect of substituted alkyl groups at different substituted position on the first excited-state proton transfer of nR7AI-H2 O (n = 2-6; R = CH3 , C2 H5 , CF3 ) complexes were theoretically investigated at the TD-M06-2X/6-31 + G(d, p) level. Here n value denoted the substituted position Cn of R group. The replacement of alkyl R group had no effect on the features of HOMO and LUMO, but influenced the S0  → S1 adiabatic transition energies of the nR7AI-H2 O complex. Through computation, we found that the double proton transfer took place in a concerted but asynchronous protolysis pattern regardless of substituted group R and substituted position in the nR7AI-H2 O complex...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Yan-Zhen Ma, Yun-Fan Yang, Wei Shi, Yu-Zhi Song, Yong-Qing Li
Dolores Reyman et al. found the norharmane (9H-pyrido [3,4-b] indole) (NHM) and two acetic acid molecules can form the ternary complex (NHM-2A) in component solvent of dichloromethane and acetic acid via the hydrogen bond chain (J. Lumin. 2014, 148, 64). But the specific reaction details during this process were rarely reported. In this study, we will give an insight into the reasons which promote the occurrence of this reaction as well as its reaction order. The hydrogen bond enhancing behavior in first excited state (S1 ) is verified through the analysis of geometric configurations, infrared spectra, frontier molecular orbitals and potential energy curves...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Lixia Cui, Honghong Zhang, Guomei Zhang, Ying Zhou, Li Fan, Lihong Shi, Caihong Zhang, Shaomin Shuang, Chuan Dong
Spiropyran compounds are well known as an isomeric system, the closed spiropyran (SP) could be converted into the open merocyanine (MC) via acid-induced because stable protonated merocyanine (MCH) were formed by combination of MC and H+ . In order to understand how the substituent affect the isomerization of spiropyran. A series of the chromene 7-subsituted spiropyran compounds were designed and synthesized. The photophysical properties of them were studied comparatively by UV-absorption and fluorescence spectra in different pH...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Nuo Duan, Shijia Wu, Huiling Zhang, Ying Zou, Zhouping Wang
An F0 F1 -ATPase-based aptasensor is described for the fluorometric determination of Vibrio parahaemolyticus. Chromatophores containing F0 F1 -ATPases were first prepared from Rhodospirillum rubrum cells. Then, an aptamer-functionalized chromatophore acts as the capture probe, and a chromatophore labeled with the pH probe fluorescein acts as the signalling probe. In the presence of V. parahaemolyticus, the rotation rate of F0 F1 -ATPase is decreased due to the formation of the aptamer-chromatophore complex...
May 18, 2018: Mikrochimica Acta
Jie Cao, Qian-Qian Jin, Gui-Ming Wang, Hong-Lin Dong, Yong-Ming Feng, Jun-Sheng Tian, Ke-Ming Yun, Ying-Yuan Wang, Jun-Hong Sun
Deep vein thrombosis (DVT) and pulmonary embolism (PE) have high morbidity, reduce quality of life, and can cause death. Biomarkers or genetic risk factors have not been identified in patients with DVT. In present study, serum of 61 patients suffering from DVT and a rat DVT model (n = 10) were assayed by a proton nuclear magnetic resonance (1 H NMR) metabolomics technique combing with multivariate statistical analysis to identify the metabolites. The MetPA platform was used to identify differences in the metabolic pathways between the rat model and patients...
May 18, 2018: Scientific Reports
Hélène Fleurbaey, Sandrine Galtier, Simon Thomas, Marie Bonnaud, Lucile Julien, François Biraben, François Nez, Michel Abgrall, Jocelyne Guéna
We present a new measurement of the 1S-3S two-photon transition frequency of hydrogen, realized with a continuous-wave excitation laser at 205 nm on a room-temperature atomic beam, with a relative uncertainty of 9×10^{-13}. The proton charge radius deduced from this measurement, r_{p}=0.877(13)  fm, is in very good agreement with the current CODATA-recommended value. This result contributes to the ongoing search to solve the proton charge radius puzzle, which arose from a discrepancy between the CODATA value and a more precise determination of r_{p} from muonic hydrogen spectroscopy...
May 4, 2018: Physical Review Letters
Edward F Brown, Andrew Cumming, Farrukh J Fattoyev, C J Horowitz, Dany Page, Sanjay Reddy
We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e^{-}+ν[over ¯]_{e} and inverse) and is consistent with the direct Urca (n→p+e^{-}+ν[over ¯]_{e} and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature...
May 4, 2018: Physical Review Letters
Xu Feng, Feng-Kun Guo, Chien-Yeah Seng
The parity-odd effect in the standard model weak neutral current reveals itself in the long-range parity-violating nuclear potential generated by the pion exchanges in the ΔI=1 channel with the parity-odd pion-nucleon coupling constant h_{π}^{1}. Despite decades of experimental and theoretical efforts, the size of this coupling constant is still not well understood. In this Letter, we derive a soft-pion theorem relating h_{π}^{1} and the neutron-proton mass splitting induced by an artificial parity-even counterpart of the ΔI=1 weak Lagrangian and demonstrate that the theorem still holds exact at the next-to-leading order in the chiral perturbation theory...
May 4, 2018: Physical Review Letters
Viktoriia A Saveleva, Li Wang, Detre Teschner, Travis E Jones, Aldo S Gago, K Andreas Friedrich, Spyridon Zafeiratos, Robert Schloegl, Elena R Savinova
Progress in the development of the proton exchange membrane (PEM) water electrolysis technology requires decreasing the anode overpotential, where the sluggish multistep oxygen evolution reaction (OER) occurs. This calls for the understanding of the nature of the active OER sites and reaction intermediates, which are still being debated. In this work, we apply synchrotron radiation - based near ambient pressure X-ray photoelectron and absorption spectroscopies under operando conditions in order to unveil the nature of the reaction intermediates and shed light on the OER mechanism on electrocatalysts most widely used in PEM electrolyzers - electrochemical and thermal iridium oxides...
May 18, 2018: Journal of Physical Chemistry Letters
Takuya Mabuchi, Takashi Tokumasu
A reactive molecular dynamics simulation has been performed for the characterization of the relationship between proton transport and water clustering in polymer electrolyte membranes. We have demonstrated that the anharmonic two-state empirical valence bond ( aTS-EVB) model is capable of describing efficiently excess proton transport through the Grotthuss hopping mechanism within the simplicity of the theoretical framework. In order to explore the long-time diffusion behavior in PFSA membranes with statistical certainty, simulations that are longer than 10 ns are needed...
May 18, 2018: Journal of Physical Chemistry. B
Pingsheng Huang, Weisheng Guo, Guang Yang, Huijuan Song, Yuqing Wang, Chun Wang, Deling Kong, Weiwei Wang
19F MRI is of great significance for non-invasive imaging and detection of various diseases. However, the main obstacle in the application of 19F MRI agents stems from the unmet signal sensitivity, due to the poor water-solubility and restricted mobility of segments with high numbers of fluorine atoms. Herein, we report a kind of intracellular reducing microenvironment-induced amino-activatable 19F MRI nanoprobe, which can be used for specific imaging of bio-thiols. In principle, the nanoprobe has an initial architecture of hydrophobic core, where the trifluoromethyl-containing segments are compactly packed and 19F NMR/MRI signals are quenched ("OFF" state)...
May 18, 2018: ACS Applied Materials & Interfaces
Qian Wu, Zheng-Wang Qu, Lukas Omann, Elisabeth Irran, Hendrik Klare, Martin Oestreich
An efficient method for the benzenium-ion-mediated cleavage of inert Si-C(sp3) bonds is reported. By this, various tetraalkylsilanes are converted into the corresponding counteranion-stabilized silylium ions. The reaction is chemoselective in the case of hexamethyldisilane. Computations reveal a mechanism with backside attack of the proton at one of the alkyl groups. Likewise, several activated Si-C(spn) bonds (n = 3-1) react equally well, and the protocol can be extended to the generation of stannylium ions...
May 18, 2018: Angewandte Chemie
Aline Bernardes, Giulio D C D'Oliveira, Aneta Silezin, Mónika Kuzma, Szilárd Molnár, Caridad Noda Pérez, Pál Perjési
The stereochemistry of non-enzyme catalyzed nucleophilic addition of GSH to 4'-hydroxychalcone 1 and its bis-Mannich derivative 2 was investigated at different pH values (pH 3.2, 6.1, 7.4, and 8.0). The stereochemical outcome of the reactions was evaluated by HPLC-UV-Vis method. Under strongly acidic conditions (pH 3.2), an unexpected diastereoselective addition of GSH onto the bis-Mannich derivative 2 was observed. Such a selectivity could not be observed in the similar reaction of 2 with N-acetylcysteine...
May 18, 2018: Archiv der Pharmazie
Mate Szarka, Szabolcs Szilasi, Boglarka Donczo, Daniel Sarkozy, Istvan Rajta, Andras Guttman
On a roundtrip to Mars, astronauts are expectedly exposed to an approximate amount of radiation that exceeds the lifetime limits on Earth. This elevated radiation dose is mainly due to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE). Specific patterns of the N-glycosylation of human immunoglobulins have already been associated with various ailments such as autoimmune diseases, malignant transformation, chronic inflammation and ageing. The focus of our work was to investigate the effect of low-energy proton irradiation on the IgG N-glycosylation profile with the goal if disease associated changes could be detected during space travel and not altered by space radiation...
May 18, 2018: Electrophoresis
Daniel Morales Salazar, Arvind Kumar Gupta, Andreas Orthaber
A P[double bond, length as m-dash]C heavy-alkene analogue that is unreactive towards the addition of strong acids on its double-bond is presented; instead, a strategically located imine nitrogen on the periphery forms protonated adducts displaying hydrogen bonding interactions. These materials are significantly more stable than the parent species, demonstrating an unprecedented approach towards the stabilisation of a multiple-bonded heavy main group fragment, in this case, a phosphaalkene. An HCl adduct self-assembles with H2O into a dimeric network displaying a discrete quadrilateral hydrogen-bonded arrangement...
May 18, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Sharon L Giles, Jessica M Winfield, David J Collins, Ian Rivens, John Civale, Gail R Ter Haar, Nandita M deSouza
Background: Magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU) can palliate metastatic bone pain by periosteal neurolysis. We investigated the value of diffusion-weighted imaging (DWI) for monitoring soft tissue changes adjacent to bone during MR-guided HIFU. We evaluated the repeatability of the apparent diffusion coefficient (ADC) measurement, the temporal evolution of ADC change after sonication, and its relationship with thermal parameters. Methods: Ex-vivo experiments in lamb legs ( n = 8) were performed on a Sonalleve MR-guided HIFU system...
2018: European radiology experimental
Erwin Rieder, Martin Riegler, Aleksandar P Simić, Ognjan M Skrobić, Luigi Bonavina, Richard Gurski, Matthias Paireder, Donald O Castell, Sebastian F Schoppmann
Gastroesophageal reflux disease (GERD) is a common disorder, known to affect about 20% of the Western population. Although conventional medical or surgical treatment has proven effective, there is certainly room for improvements. As only 10% of GERD patients are finally treated by antireflux surgery, a large therapeutic window exists. This treatment gap consists of patients who are not effectively treated with proton pump inhibitor but do not want to run the potential risks of conventional surgery. During the last two decades, several novel and intriguing options for the surgical treatment of GERD have been introduced and found their way into clinical use...
May 17, 2018: Annals of the New York Academy of Sciences
F Genest, L Seefried
Risk for subtrochanteric and diaphyseal femoral fractures is considered increased in patients with hypophosphatasia (HPP). Evaluating a large cohort of HPP patients, we could for the first time quantify the prevalcence and identify both morphometric features as well as predisposing factors for this complication of severe HPP. INTRODUCTION: Subtrochanteric and diaphyseal femoral fractures have been associated with both, long-term antiresorptive treatment and metabolic bone disorders, specifically Hypophosphatasia (HPP)...
May 17, 2018: Osteoporosis International
Dongxue Han, Jianlei Han, Shengwei Huo, Zuoming Qu, Tifeng Jiao, Minghua Liu, Pengfei Duan
The orthogonal- or co-assembly of achiral perylene bisimide (PBI) with chiral gelators can be regulated by solvents. While the coassembly leads to the formation of chiroptical nanofibers through chirality transfer, the orthogonal assemblies could not. Moreover, protonation on the coassembled nanofibers could light up the circularly polarized luminescence (CPL).
May 18, 2018: Chemical Communications: Chem Comm
Mimi Kim, Bo-Kyeong Kang, Dae Won Jun
This study correlated conventional ultrasonography (US) signs with the magnetic resonance imaging (MRI) proton density fat fraction (PDFF) to evaluate the diagnostic performance of US signs (alone or combined) to predict presence and degree of hepatic steatosis (HS). Overall, 182 subjects met the study inclusion criteria between February 2014 and October 2016. Four US signs were evaluated independently by two radiologists. MRI PDFF was defined as the average of 24 non-overlapping regions of interest (ROIs) within eight liver segments obtained by drawing three ROIs within each segment...
May 17, 2018: Scientific Reports
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