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G Kalaiarasi, S Rex Jeya Rajkumar, G Aswini, S Dharani, Frank R Fronczek, R Prabhakaran
A series of 3-acetyl-8-methoxycoumarin appended thiosemicarbazones (1-4) was prepared from the reaction of 3-acetyl-8-methoxycoumarin with 4(N)-substituted thiosemicarbazides in a view of ascertaining their biological properties with the change of N-terminal substitution in the thiosemicarbazide moiety. Comprehensive characterization was brought about by various spectral and analytical methods. The molecular structures of all the compounds were determined by single crystal X-ray diffraction analysis. Binding studies with Calf thymus DNA (CT-DNA) and proteins such as Bovine Serum Albumin (BSA) and Human Serum Albumin (HSA) indicated an intercalative mode of binding with DNA and static quenching mechanism with proteins...
April 14, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Zaineb Fourati, Rebecca J Howard, Stephanie A Heusser, Haidai Hu, Reinis R Ruza, Ludovic Sauguet, Erik Lindahl, Marc Delarue
Ion channel modulation by general anesthetics is a vital pharmacological process with implications for receptor biophysics and drug development. Functional studies have implicated conserved sites of both potentiation and inhibition in pentameric ligand-gated ion channels, but a detailed structural mechanism for these bimodal effects is lacking. The prokaryotic model protein GLIC recapitulates anesthetic modulation of human ion channels, and it is accessible to structure determination in both apparent open and closed states...
April 24, 2018: Cell Reports
Karlo Komorowski, Annalena Salditt, Yihui Xu, Halenur Yavuz, Martha Brennich, Reinhard Jahn, Tim Salditt
We have studied the adhesion state (also denoted by docking state) of lipid vesicles as induced by the divalent ions Ca2+ or Mg2+ at well-controlled ion concentration, lipid composition, and charge density. The bilayer structure and the interbilayer distance in the docking state were analyzed by small-angle x-ray scattering. A strong adhesion state was observed for DOPC:DOPS vesicles, indicating like-charge attraction resulting from ion correlations. The observed interbilayer separations of ∼1.6 nm agree quantitatively with the predictions of electrostatics in the strong coupling regime...
April 24, 2018: Biophysical Journal
Rui Xu, Xin-Chun Cheng, Yuan Zhang, Hong-Mei Lai, Hong-Ni Yang
BACKGROUND: Coronary artery disease (CAD) and osteoporosis (OP) are common diseases in postmenopausal women. In both cross-sectional and longitudinal epidemiologic studies, low bone mass has been related to increased frequency of CAD. However, available data on the relationship between bone mineral density (BMD) and severity of coronary lesions is limited. OBJECTIVE: To investigate association between the BMD and severity of coronary lesions assessed by Gensini score in postmenopausal women...
March 2018: Arquivos Brasileiros de Cardiologia
Ryo Kitamura, Katsunori Suzuki, Makoto Yamashita
Boryl- and amino-substituted acetylenes bearing diphenylboryl or 9-borabicyclononyl groups were synthesized. X-ray diffraction analyses revealed the dimerized structures of these acetylenes via the formation of B2C2 four-membered rings. Spectroscopic studies and DFT calculations indicated that these dimers can dissociate to afford monomeric acetylenes, and that the equilibrium constant for the dissociation depends on the structure of the boryl substituents.
April 25, 2018: Chemical Communications: Chem Comm
Qiqing Li, Xiaodan Li, Li Zhang, Jing Zuo, Youlin Zhang, Xiaomin Liu, Langping Tu, Bin Xue, Yulei Chang, Xianggui Kong
Multimodality imaging-guided therapy based on lanthanide-doped upconversion nanoparticles (UCNPs) has become a trend in cancer theranostics. However, the overheating effect of 980 nm excitation in photodynamic therapy (PDT) and the difficulties in optimizing multimodality imaging integration within a single particle are still challenges. Herein, 800 nm driven NaErF4@NaLuF4 UCNPs have been explored for optimized multimodality imaging and near-infrared (NIR) triggered PDT. Our results confirmed that the optimal ∼5 nm shell thickness can well balance the enhancement of upconversion luminescence and the attenuation of energy transfer efficiency from Er3+ towards a photosensitizer, to achieve efficient production of singlet oxygen (1O2) for PDT under 800 nm excitation...
April 25, 2018: Nanoscale
Bin Wu, Takuya Iwashita, Takeshi Egami
The de Gennes narrowing phenomenon is frequently observed by neutron or x-ray scattering measurements of the dynamics of complex systems, such as liquids, proteins, colloids, and polymers. The characteristic slowing down of dynamics in the vicinity of the maximum of the total scattering intensity is commonly attributed to enhanced cooperativity. In this Letter, we present an alternative view on its origin through the examination of the time-dependent pair correlation function, the van Hove correlation function, for a model liquid in two, three, and four dimensions...
March 30, 2018: Physical Review Letters
Sally June Tracy, Stefan J Turneaure, Thomas S Duffy
Because of its widespread applications in materials science and geophysics, SiO_{2} has been extensively examined under shock compression. Both quartz and fused silica transform through a so-called "mixed-phase region" to a dense, low compressibility high-pressure phase. For decades, the nature of this phase has been a subject of debate. Proposed structures include crystalline stishovite, another high-pressure crystalline phase, or a dense amorphous phase. Here we use plate-impact experiments and pulsed synchrotron x-ray diffraction to examine the structure of fused silica shock compressed to 63 GPa...
March 30, 2018: Physical Review Letters
So Yeun Kim, Tae Yun Kim, Luke J Sandilands, Soobin Sinn, Min-Cheol Lee, Jaeseok Son, Sungmin Lee, Ki-Young Choi, Wondong Kim, Byeong-Gyu Park, C Jeon, Hyeong-Do Kim, Cheol-Hwan Park, Je-Geun Park, S J Moon, T W Noh
Strong charge-spin coupling is found in a layered transition-metal trichalcogenide NiPS_{3}, a van der Waals antiferromagnet, from studies of the electronic structure using several experimental and theoretical tools: spectroscopic ellipsometry, x-ray absorption, photoemission spectroscopy, and density functional calculations. NiPS_{3} displays an anomalous shift in the optical spectral weight at the magnetic ordering temperature, reflecting strong coupling between the electronic and magnetic structures. X-ray absorption, photoemission, and optical spectra support a self-doped ground state in NiPS_{3}...
March 30, 2018: Physical Review Letters
Martin Lüttich, Valentina M Giordano, Sylvie Le Floch, Eloi Pineda, Federico Zontone, Yuansu Luo, Konrad Samwer, Beatrice Ruta
As ultrastable metallic glasses (UMGs) are promising candidates to solve the stability issues of conventional metallic glasses, their study is of exceptional interest. By means of x-ray photon correlation spectroscopy, we have investigated the stability of UMGs at the atomic level. We find a clear signature of ultrastability at the atomic level that results in slower relaxation dynamics of UMGs with respect to conventional (rapidly quenched) metallic glasses, and in a peculiar acceleration of the dynamics by near T_{g} annealing...
March 30, 2018: Physical Review Letters
Thomas Kroll, Clemens Weninger, Roberto Alonso-Mori, Dimosthenis Sokaras, Diling Zhu, Laurent Mercadier, Vinay P Majety, Agostino Marinelli, Alberto Lutman, Marc W Guetg, Franz-Josef Decker, Sébastien Boutet, Andy Aquila, Jason Koglin, Jake Koralek, Daniel P DePonte, Jan Kern, Franklin D Fuller, Ernest Pastor, Thomas Fransson, Yu Zhang, Junko Yano, Vittal K Yachandra, Nina Rohringer, Uwe Bergmann
We report the observation and analysis of the gain curve of amplified Kα x-ray emission from solutions of Mn(II) and Mn(VII) complexes using an x-ray free electron laser to create the 1s core-hole population inversion. We find spectra at amplification levels extending over 4 orders of magnitude until saturation. We observe bandwidths below the Mn 1s core-hole lifetime broadening in the onset of the stimulated emission. In the exponential amplification regime the resolution corrected spectral width of ∼1...
March 30, 2018: Physical Review Letters
Florent Bories, Doru Constantin, Paolo Galatola, Jean-Baptiste Fournier
The activity of cell membrane inclusions (such as ion channels) is influenced by the host lipid membrane, to which they are elastically coupled. This coupling concerns the hydrophobic thickness of the bilayer (imposed by the length of the channel, as per the hydrophobic matching principle) but also its slope at the boundary of the inclusion. However, this parameter has never been measured so far. We combine small-angle x-ray scattering data and a complete elastic model to measure the slope for the model gramicidin channel and show that it is surprisingly steep in two membrane systems with very different elastic properties...
March 23, 2018: Physical Review Letters
D T Michel, I V Igumenshchev, A K Davis, D H Edgell, D H Froula, D W Jacobs-Perkins, V N Goncharov, S P Regan, A Shvydky, E M Campbell
Multiple self-emission x-ray images are used to measure tomographically target modes 1, 2, and 3 up to the end of the target acceleration in direct-drive implosions on OMEGA. Results show that the modes consist of two components: the first varies linearly with the laser beam-energy balance and the second is static and results from physical effects including beam mistiming, mispointing, and uncertainty in beam energies. This is used to reduce the target low modes of low-adiabat implosions from 2.2% to 0.8% by adjusting the beam-energy balance to compensate these static modes...
March 23, 2018: Physical Review Letters
U Hejral, D Franz, S Volkov, S Francoual, J Strempfer, A Stierle
Pt-Rh alloy nanoparticles on oxide supports are widely employed in heterogeneous catalysis with applications ranging from automotive exhaust control to energy conversion. To improve catalyst performance, an atomic-scale correlation of the nanoparticle surface structure with its catalytic activity under industrially relevant operando conditions is essential. Here, we present x-ray diffraction data sensitive to the nanoparticle surface structure combined with in situ mass spectrometry during near ambient pressure CO oxidation...
March 23, 2018: Physical Review Letters
Jian-Xing Li, Yue-Yue Chen, Karen Z Hatsagortsyan, Christoph H Keitel
The impact of the carrier-envelope phase (CEP) of an intense multicycle laser pulse on the radiation of an electron beam during nonlinear Compton scattering is investigated. We have identified a CEP effect specific to the ultrarelativistic regime. When the electron beam counterpropagates with the laser pulse, pronounced high-energy x-ray double peaks emerge near the backward direction relative to the initial electron motion. This is achieved in the relativistic interaction domain, where both the electron energy is required to be lower than for the electron reflection condition at the laser peak and the stochasticity effects in the photon emission need to be weak...
March 23, 2018: Physical Review Letters
Fumitaka Yoshimura, Hisanori Yamane
Single crystals of new boron-aluminum-silicon nitrides, Sr3 BAl5 Si9 N20 and Sr2.91 Eu0.09 BAl5 Si9 N20 , were synthesized by heating binary nitride mixtures at 2030 °C under a N2 pressure of 0.85 MPa. The X-ray diffraction spots from single crystals of these two compounds were indexed with the trigonal cell parameters a = 22.7406(8) Å, c = 5.7066(2) Å and a = 22.7439(8) Å, c = 5.7050(2) Å, respectively, and the crystal structures were determined to have the space group P3 c1, with B atoms situated at planar 3-fold-coordinated N sites...
April 25, 2018: Inorganic Chemistry
Nico M Bonanno, Alan J Lough, Martin T Lemaire
We describe the structural features and magnetic properties of two polynuclear copper(II) complexes containing a redox-active ligand. These neutral complexes each bear the formula RL4 Cu4 (R = t Bu, Me) with the ligand in a dianion-aminyl radical oxidation state. X-ray data and density functional theory calculations support an aminyl-type radical character in these complexes, making these the first polynuclear metal aminyl radical complexes.
April 25, 2018: Inorganic Chemistry
Yuma Morimoto, Yusaku Takagi, Toru Saito, Takehiro Ohta, Takashi Ogura, Norimitsu Tohnai, Motohiro Nakano, Shinobu Itoh
A bis(µ-oxido)dinickel(III) complex is synthesized and characterized by single crystal X-ray diffraction, resonance Raman, and ESI-mass spectroscopies. Magnetic susceptibility measurement by SQUID and EPR reveal that the complex has a triplet ground state, which is unprecedented for high-valent metal (M) complex with [M2(µ-O)2] diamond core. DFT studies indicate ferromagnetic coupling of the nickel(III) centers. The complex exhibits hydrogen abstraction reactivity and oxygenation reactivity toward external substrates...
April 25, 2018: Angewandte Chemie
Francisco M García-Valle, Vanessa Tabernero, Tomás Cuenca, Jesús Cano, Marta E G Mosquera
New heterobimetallic aluminates with well-defined structures bearing bidentate Schiff bases as ligands have been prepared. The ligands studied are PhO-CH[double bond, length as m-dash]N-Ar (Ar = C6H5 (La) and 2,6-iPr-C6H3 (Lb)), with and without donor substituents in the ortho position of the arene ring bonded to the iminic nitrogen. To prepare the heterometallic species, the HL proligands were treated with the appropriate alkali metal precursor and then AlMe3 was added. In these reactions the alkali metal size has a substantial influence on the outcome...
April 25, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Tran Thi Thuong Huyen, Tran Thi Kim Chi, Nguyen Duc Dung, Hendrik Kosslick, Nguyen Quang Liem
Rutile TiO₂ with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple hydrothermal synthesis of rutile TiO₂ nanorods with highly exposed {110} facets. The obtained rutile was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy...
April 25, 2018: Nanomaterials
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