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Silvia Casabianca, Antonella Penna, Samuela Capellacci, Michela Cangiotti, Maria Francesca Ottaviani
The silicon transport and use inside cells are key processes for understanding how diatoms metabolize this element in the silica biogenic cycle in the ocean. A spin-probe electron paramagnetic resonance (EPR) study over time helped to investigate the interacting properties and the internalization mechanisms of silicic acid from different silicon sources into the cells. Diatom cells were grown in media containing biogenic amorphous substrates, such as diatomaceous earth and sponge spicules, and crystalline sodium metasilicate...
November 14, 2017: Colloids and Surfaces. B, Biointerfaces
Augustin C Mot, Cristina Bischin, Grigore Damian, Amr A A Attia, Emese Gal, Nicoleta Dina, Nicolae Leopold, Radu Silaghi-Dumitrescu
The present study reports findings regarding the contrast between H2S interaction with bovine hemoglobin (Hb) and horse heart myoglobin (Mb), in terms of binding and dissociation kinetics, affinities, and mechanism. At pH9.5, oxidation of ferric-sulfide adducts in presence of no free sulfide, using hexachloroiridate as oxidant is examined using stopped-flow UV-vis, EPR, vibrational spectroscopy and mass spectrometry. Oxidation of the ferric-sulfide adduct in such conditions occurs with a putative unstable Fe(IV)-sulfide adduct as intermediate that finally leads to a paramagnetic ferric species with distinct EPR features...
November 10, 2017: Journal of Inorganic Biochemistry
Alexey A Malygin, Dmitri M Graifer, Maria I Meschaninova, Alya G Venyaminova, Ivan O Timofeev, Andrey A Kuzhelev, Olesya A Krumkacheva, Matvey V Fedin, Galina G Karpova, Elena G Bagryanskaya
The model mRNA (MR), 11-mer RNA containing two nitroxide spin labels at the 5'- and 3'-terminal nucleotides and prone to form a stable homodimer (MR)2, was used for Electron Paramagnetic Resonance study of structural rearrangements in mRNA occurring upon its binding to human 80S ribosomes. The formation of two different types of ribosomal complexes with MR was observed. First, there were stable complexes where MR was fixed in the ribosomal mRNA-binding channel by the codon-anticodon interaction(s) with cognate tRNA(s)...
November 16, 2017: Nucleic Acids Research
Anastasia Kultaeva, Timur Biktagirov, Jens Bergmann, Linda Hensel, Harald Krautscheid, Andreas Pöppl
Continuous wave X-band electron paramagnetic resonance (EPR) and density functional theory (DFT) were successfully applied to explore the incorporation and coordination state of the Cu(2+) ions in the [Cd0.98Cu0.02(prz-trz-ia)] porous metal-organic frameworks. EPR measurements on powder samples and single crystals provided the full electron Zeeman g and copper hyperfine A(Cu) interaction tensors including the orientation of their principal axes frames. DFT computations allowed for a detailed interpretation of the experimental results in terms of coordination symmetry and binding properties of the paramagnetic Cu(2+) ions...
November 20, 2017: Physical Chemistry Chemical Physics: PCCP
Maximilian Dürr, Johannes Klein, Axel Kahnt, Sabine Becker, Ralph Puchta, Biprajit Sarkar, Ivana Ivanović-Burmazović
A dinuclear ruthenium complex bridged by 2,3,5,6-pyrazinetetracarboxylic acid (μ-LH2(2-)) was synthesized and characterized by X-ray crystallography, cyclic voltammetry under ambient and elevated pressures, electron paramagnetic resonance (EPR) and UV/vis-NIR (NIR = near-infrared) spectroelectrochemistry, pulse radiolysis, and computational methods. We probed for the first time in the field of mixed-valency the use of high-pressure electrochemical methods. The investigations were directed toward the influence of the protonation state of the bridging ligand on the electronic communication between the ruthenium ions, since such behavior is interesting in terms of modulating redox chemistry by pH...
November 20, 2017: Inorganic Chemistry
Ingo Krossing, Miriam Mareen Schwab, Daniel Himmel, Sylwia Kacprzak, Valentin Radtke, Daniel Kratzert, Philippe Weis, Melanie Wernet, Andreas Peter, Zeinab Yassine, Dominik Schmitz, Ernst-Wilhelm Scheidt, Wolfgang Scherer, Stefan Weber, Wolfram Feuerstein, Frank Breher, Alexander Higelin
The recently published purely metalorganic NiI salt [Ni(cod)2][Al(ORF)4] (1, cod = 1,5-cyclooctadiene, RF = C(CF3)3) provides a starting point for a new synthesis strategy leading to NiI phosphine complexes, replacing cod ligands by phosphines. Clearly visible colour changes indicate reactions within minutes, while quantum chemical calculations (PBE0-D3(BJ)/def2-TZVPP) approve exergonic reaction enthalpies in all performed ligand exchange reactions. Hence, [Ni(dppp)2][Al(ORF)4] (2, dppp = 1,3-Bis(diphenylphosphino)propane), [Ni(dppe)2][Al(ORF)4] (3, dppe = 1,3-Bis(diphenyl-phosphino)ethane), three-coordinate [Ni(PPh3)3][Al(ORF)4] (4) and a remarkable two-coordinate NiI phosphine complex [Ni(PtBu3)2][Al(ORF)4] (5) were characterised via single crystal X-ray structure analysis...
November 20, 2017: Chemistry: a European Journal
Ivan Salitros, Lukáš Pogány, Barbora Brachňaková, Jan Moncol, Jan Pavlik, Ivan Nemec, Zdeněk Trávniček, Milan Mazúr, Lukáš Bučinský, Ľubomír Suchánek
A series of novel iron(III) complexes of the general formula [Fe(L)X] (where L stands for a dianion of pentadentate Schiff base ligand N,N'-bis((2-hydroxy-3,5-dimethylphenyl)phenyl)methylidene-1,6-diamino-3-azapentane=H2L1 for 1 and 2; N,N'-bis((2-hydroxy-3-ethoxyphenyl)methylidene)-1,6-diamino-3-azapentane=H2L2 for 3 and 3·C3H6O) and X is terminal pseudohalido ligand (X=N3 for 1, X=NCS for 2, and X=NCSe for 3 and 3·C3H6O) has been synthesized and thoroughly characterized. Magnetic measurements revealed the above room temperature spin crossover for isomorphic complexes 1 and 2 (T1/2 = 441 K and T1/2 = 435 K, respectively), while the solvent-free complex 3 showed a half complete spin crossover (T1/2 = 250 K), which was detected by a variable temperature crystallography as well...
November 20, 2017: Chemistry: a European Journal
M Studenovsky, L Sivak, O Sedlacek, R Konefal, V Horkova, T Etrych, M Kovar, B Rihova, M Sirova
The delivery of nitric oxide (NO) specifically to solid tumours was explored in this study as a strategy to augment the passive accumulation of nanomedicines in tumours induced by the Enhanced Permeability and Retention (EPR) effect. An increase in accumulation was achieved by the binding of the chemical precursor of NO, based on an organic nitrate, to a water-soluble synthetic polymer drug carrier. Four structurally different N-(2-hydroxypropyl)methacrylamide (HPMA)-based polymer NO donors were synthesized...
November 15, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Jinyuan Ma, Yang Li, Guihua Liu, Ai Li, Yilin Chen, Xinyi Zhou, Dengyue Chen, Zhenqing Hou, Xuan Zhu
The novel drug delivery system based on self-assembly of zinc phthalocyanine-soybean phosphatidylcholine (ZnPc-SPC) complex was developed by a co-solvent method followed by a nanoprecipitaion technique. DSPE-PEG-methotrexate (DSPE-PEG-MTX) was introduced on the surface of ZnPc-SPC self-assembled nanoparticles (ZS) to endow them with folate receptor-targeting property. NMR, XRD, FTIR, and UV-vis-NIR analysis demonstrated the weak molecular interaction between ZnPc and SPC. The ZS functionalized with DSPE-PEG-MTX (ZSPM) was successfully constructed with an average particle size of ∼170nm, a narrow size distribution, and could remain physiologically stable for at least 7days...
October 24, 2017: Colloids and Surfaces. B, Biointerfaces
Chieu D Tran, James Makuvaza, Erik Munson, Brian Bennett
Copper in various forms has been known to have bactericidal activity. Challenges to its application include preventing mobilization of the copper, to both extend activity and avoid toxicity, and bioincompatibility of many candidate substrates for copper-immobilization. Using a simple ionic liquid, butylmethylimmidazolium chloride as the solvent, we developed a facile and green method to synthesize biocompatible composites containing copper oxide nanoparticles (CuONPs) from cellulose (CEL) and chitosan (CS) or CEL and keratin (KER)...
November 20, 2017: ACS Applied Materials & Interfaces
Abul Arif, Peng Yao, Fulvia Terenzi, Jie Jia, Partho Sarothi Ray, Paul L Fox
The interferon (IFN)-γ-activated inhibitor of translation (GAIT) system directs transcript-selective translational control of functionally related genes. In myeloid cells, IFN-γ induces formation of a multiprotein GAIT complex that binds structural GAIT elements in the 3'-untranslated regions (UTRs) of multiple inflammation-related mRNAs, including ceruloplasmin and VEGF-A, and represses their translation. The human GAIT complex is a heterotetramer containing glutamyl-prolyl tRNA synthetase (EPRS), NS1-associated protein 1 (NSAP1), ribosomal protein L13a (L13a), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH)...
November 20, 2017: Wiley Interdisciplinary Reviews. RNA
Kejia Zhang, Xinyan Zhou, Tuqiao Zhang, Lang Yu, Zheming Qian, Wenchao Liao, Cong Li
2,4,6-Trichloroanisole (TCA) is an odorous compound that is often detected in tap water and is difficult to be removed via water treatment. In this study, the transformation efficiency of TCA in the presence of persulfate (PS) activated by iron (Fe(2+), Fe(0), and Fe(3+)) was investigated for the first time. The effects of the activator dosage, oxidant dosage, pH, dosing method, chelating agents, humic acid, and temperature were evaluated. The degradation rate of TCA increased with increasing PS dosages (0...
November 19, 2017: Environmental Science and Pollution Research International
Sarah Bouhadoun, Chantal Guillard, Sébastien Sorgues, Alexandre Hérissan, Christophe Colbeau-Justin, Frederic Dapozze, Aurélie Habert, Vincent Maurel, Nathalie Herlin-Boime
Titanium dioxide nanoparticles were synthesized by laser pyrolysis, their surface and electronic properties were modified by gold and/or nitrogen. These materials were characterized by different techniques like X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Time resolved conductivity (TRMC) was used to study the charge separation of electron/hole pairs. Altogether (XPS, EPR, TRMC), the physicochemical characterizations are well correlated with chemical photoactivity of the different samples...
2017: Science and Technology of Advanced Materials
Subramanian V Sundramoorthy, Boris Epel, Howard J Halpern
A magnetometer designed for permanent magnet manufacturing and operated around 25 mT with 10ppm absolute accuracy is described. The magnetometer uses pulse electron paramagnetic resonance (EPR) methodology. The use of a pulsed broadband acquisition allowed reliable measurements in the presence of the magnetic field gradient and in relatively inhomogeneous magnetic fields of un-shimmed magnets.
August 2017: Applied Magnetic Resonance
Jason W Sidabras, Edward J Reijerse, Wolfgang Lubitz
Uniform field (UF) resonators create a region-of-interest, where the sample volume receives a homogeneous microwave magnetic field ([Formula: see text]) excitation. However, as the region-of-interest is increased, resonator efficiency is reduced. In this work, a new class of uniform field resonators is introduced: the uniform field re-entrant cylindrical TE[Formula: see text] cavity. Here, a UF cylindrical TE[Formula: see text] cavity is designed with re-entrant fins to increase the overall resonator efficiency to match the resonator efficiency maximum of a typical cylindrical TE[Formula: see text] cavity...
2017: Applied Magnetic Resonance
Klaus Möbius, Wolfgang Lubitz, Anton Savitsky
In this minireview, we report on our year-long EPR work, such as electron-nuclear double resonance (ENDOR), pulse electron double resonance (PELDOR) and ELDOR-detected NMR (EDNMR) at X-band and W-band microwave frequencies and magnetic fields. This report is dedicated to James S. Hyde and honors his pioneering contributions to the measurement of spin interactions in large (bio)molecules. From these interactions, detailed information is revealed on structure and dynamics of macromolecules embedded in liquid-solution or solid-state environments...
2017: Applied Magnetic Resonance
Zhihua Chen, Xiangjun Ye, Shao-Ming Fei
Occupying a position between entanglement and Bell nonlocality, Einstein-Podolsky-Rosen (EPR) steering has attracted increasing attention in recent years. Many criteria have been proposed and experimentally implemented to characterize EPR-steering. Nevertheless, only a few results are available to quantify steerability using analytical results. In this work, we propose a method for quantifying the steerability in two-qubit quantum states in the two-setting EPR-steering scenario, using the connection between joint measurability and steerability...
November 17, 2017: Scientific Reports
Ashish Kumar Mall, Ambesh Dixit, Ashish Garg, Rajeev Gupta
We report temperature dependent electron paramagnetic resonance (EPR) studies on polycrystalline YCrO3 samples at X-band (9.46 GHz) in the temperature range of 120 K-298 K. The EPR spectra exhibit a single broad line across the whole temperature range, attributed to Cr(3+) ions. The variation of EPR spectra parameters (line width, integrated intensity, and g-factor) as a function of temperature was analyzed to understand the nature of spin-dynamics in the paramagnetic region of YCrO3. A peak in the g-factor suggests the presence of a new phase within the paramagnetic state at an intermediate point of temperature T IP ~ 230 K, attributed to the onset of short range canted antiferromagnetic correlations in the material much above 140 K, Néel temperature (T N) of YCrO3...
November 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
K Michael Schäfer, Leonie Reinders, Jan Fiedler, Mark R Ringenberg
Recently we had reported the noninnocent behavior of 1,1'-bis(diphenylphosphino)ferrocene (dppf) in Fe(CO)3dppf [Ringenberg et al., Inorg. Chem., 2017, 56, 7501]. Moving to the left in the periodic table, HMn(CO)3(dRpf) where dRpf = dppf (1H) and 1,1'-bis(diisopropylphosphino)ferrocene (dippf) (2H) were synthesized. The hydride ligand was removed by protonation with [(Et2O)2H][B(Ar(F))4] ([B(Ar(F))4](-) = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate), resulting in the rapid evolution of H2 followed by the formation of an Fe→Mn interaction...
November 16, 2017: Inorganic Chemistry
Ken-Ichiro Matsumoto, Fuminori Hyodo, James B Mitchell, Murali C Krishna
PURPOSE: Pharmacokinetics of the tri[8-carboxy-2,2,6,6-tetrakis(2-hydroxymethyl)benzo[1,2-d:4,5-d']bis(1,3)dithio-4-yl]methyl radical (Oxo63) after a single bolus and/or continuous intravenous infusion was investigated in tumor-bearing C3H mice with or without body temperature control while under anesthesia. METHOD: The in vivo time course of Oxo63 in blood was measured using X-band electron paramagnetic resonance spectroscopy. Distribution of Oxo63 in normal muscle and tumor tissues was obtained using a surface coil resonator and a 700-MHz electron paramagnetic resonance spectrometer...
November 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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