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https://www.readbyqxmd.com/read/28431460/paramagnetic-intrinsic-defects-in-polycrystalline-large-area-2d-mos2-films-grown-on-sio2-by-mo-sulfurization
#1
A Stesmans, S Iacovo, D Chiappe, I Radu, C Huyghebaert, S De Gendt, V V Afanas'ev
A low-temperature electron spin resonance study has been carried out on large-area high-purity polycrystalline two-dimensional few monolayer (ML) 2H MoS2 films synthesized by sulfurization of Mo layers, with intent to atomically assess mobility-degrading detrimental point defects. This reveals the presence of a distinct previously unreported anisotropic defect of axial symmetry about the c-axis characterized by g // = 2.00145 and g ⊥ = 2.0027, with corresponding density (spin S = ½) ~3 × 10(12) cm(-2) for a 4 ML thick film...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28430422/gauging-donor-acceptor-properties-and-redox-stability-of-chelating-click-derived-triazoles-and-triazolylidenes-a-case-study-with-rhenium-i-complexes
#2
Lisa Suntrup, Sinja Klenk, Johannes Klein, Sebastian Sobottka, Biprajit Sarkar
Bidentate ligands containing at least one triazole or triazolylidene (mesoionic carbene, MIC) unit are extremely popular in contemporary chemistry. One reason for their popularity is the similarities as well as differences in the donor/acceptor properties that these ligands display in comparison to their pyridine or other N-heterocyclic carbene counterparts. We present here seven rhenium(I) carbonyl complexes where the bidentate ligands contain combinations of pyridine/triazole/triazolylidene. These are the first examples of rhenium(I) complexes with bidentate 1,2,3-triazol-5-ylidene-containing ligands...
April 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28430379/-17-o-mrs-assesses-the-effect-of-mild-hypothermia-on-oxygen-consumption-rate-in-tumors
#3
Marie-Aline Neveu, Nicolas Joudiou, Géraldine De Preter, Jean-Paul Dehoux, Bénédicte F Jordan, Bernard Gallez
Although oxygen consumption is a key factor in metabolic phenotyping, its assessment in tumors remains critical, as current technologies generally display poor specificity. The objectives of this study were to explore the feasibility of direct (17) O nuclear magnetic resonance (NMR) spectroscopy to assess oxygen metabolism in tumors and its modulations. To investigate the impact of hypometabolism induction in the murine fibrosarcoma FSAII tumor model, we monitored the oxygen consumption of normothermic (37°C) and hypothermic (32°C) tumor-bearing mice...
April 21, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28430197/g-quadruplex-organic-frameworks
#4
Yi-Lin Wu, Noah E Horwitz, Kan-Sheng Chen, Diego A Gomez-Gualdron, Norman S Luu, Lin Ma, Timothy C Wang, Mark C Hersam, Joseph T Hupp, Omar K Farha, Randall Q Snurr, Michael R Wasielewski
Two-dimensional covalent organic frameworks often π stack into crystalline solids that allow precise spatial positioning of molecular building blocks. Inspired by the hydrogen-bonded G-quadruplexes found frequently in guanine-rich DNA, here we show that this structural motif can be exploited to guide the self-assembly of naphthalene diimide and perylene diimide electron acceptors end-capped with two guanine electron donors into crystalline G-quadruplex-based organic frameworks, wherein the electron donors and acceptors form ordered, segregated π-stacked arrays...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28430107/superconductivity-and-magnetic-fluctuations-developing-in-the-vicinity-of-strong-first-order-magnetic-transition-in-cras
#5
Hisashi Kotegawa, Kei Matsushima, Shingo Nakahara, Hideki Tou, Jun Kanetoshi, Taihei Nishiwaki, Eiichi Matsuoka, Hitoshi Sugawara, Hisatomo Harima
We report single crystal preparation, resistivity, and nuclear quadrupole resonance (NQR) measurements for new pressure-induced superconductor CrAs. In the first part, we present the difference between crystals made by different thermal sequences and methods, and show the sample dependence of superconductivity in CrAs. In the latter part, we show NQR data focusing the microscopic electronic state at the phase boundary between the helimagnetic (HM) and the paramagnetic (PM) phases. They suggest strongly that a quantum critical point is absent on the pressure-temperature phase diagram of CrAs, because of the strong first-order character of the magnetic transition; however, the spin fluctuations are observed in the PM phase...
April 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28429936/electron-decoupling-with-dynamic-nuclear-polarization-in-rotating-solids
#6
Edward P Saliba, Erika L Sesti, Faith J Scott, Brice J Albert, Eric J Choi, Nicholas Alaniva, Chukun Gao, Alexander B Barnes
Dynamic nuclear polarization (DNP) can enhance NMR sensitivity by orders of magnitude by transferring spin polarization from electron paramagnetic resonance (EPR) to NMR. However, paramagnetic DNP polarizing agents can have deleterious effects on NMR signals. Electron spin decoupling can mitigate these paramagnetic relaxation effects. We demonstrate electron decoupling experiments in conjunction with DNP and magic angle spinning (MAS) NMR spectroscopy. Following a DNP and spin diffusion period, the microwave irradiation frequency is quickly tuned on-resonance with electrons on the DNP polarizing agent...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28429253/modified-metformin-as-a-more-potent-anticancer-drug-mitochondrial-inhibition-redox-signaling-antiproliferative-effects-and-future-epr-studies
#7
Balaraman Kalyanaraman, Gang Cheng, Micael Hardy, Olivier Ouari, Adam Sikora, Jacek Zielonka, Michael B Dwinell
Metformin, one of the most widely prescribed antidiabetic drugs in the world, is being repurposed as a potential drug in cancer treatment. Epidemiological studies suggest that metformin exerts anticancer effects in diabetic patients with pancreatic cancer. However, at typical antidiabetic doses the bioavailability of metformin is presumably too low to exert antitumor effects. Thus, more potent analogs of metformin are needed in order to increase its anticancer efficacy. To this end, a new class of mitochondria-targeted metformin analogs (or mito-metformins) containing a positively-charged lipophilic triphenylphosphonium group was synthesized and tested for their antitumor efficacy in pancreatic cancer cells...
April 21, 2017: Cell Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28422504/integrated-computational-approach-to-the-electron-paramagnetic-resonance-characterization-of-rigid-310-helical-peptides-with-toac-nitroxide-spin-labels
#8
Marco Gerolin, Mirco Zerbetto, Alessandro Moretto, Fernando Formaggio, Claudio Toniolo, Martin van Son, Maryam Hashemi Shabestari, Martina Huber, Paolo Calligari, Antonino Polimeno
We address the interpretation, via an integrated computational approach, of the experimental continuous-wave electron paramagnetic resonance (cw-EPR) spectra of a complete set of conformationally highly restricted, stable 310-helical peptides from hexa- to nonamers, each bis-labeled with nitroxide radical-containing TOAC (4-amino-1-oxyl-2,2,6,6-tetramethylpiperidine-4-carboxylic acid) residues. The usefulness of TOAC for this type of analysis has been shown already to be due to its cyclic piperidine side chain, which is rigidly connected to the peptide backbone α-carbon...
April 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28422350/electronic-g-tensors-in-u-v-complexes-a-computational-study
#9
Helen Moylan, Joseph McDouall
The theory and computation of EPR parameters from first principles has seen a great deal of development over the past two decades. In particular, various techniques for the computation of the electronic g tensor have been implemented in many quantum chemistry packages. These methods have been successfully applied to paramagnetic organic species and transition metal systems. The situation is less well-understood and established in the case of actinide containing molecules and there is a dearth of experimental data available for validation of computations...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422180/patterning-graphene-film-by-magnetic-assisted-uv-ozonation
#10
Yixuan Wu, Haihua Tao, Shubin Su, Huan Yue, Hao Li, Ziyu Zhang, Zhenhua Ni, Xianfeng Chen
Developing an alternative method for fabricating microscale graphene patterns that overcomes the obstacles of organic contamination, linewidth resolution, and substrate damaging is paramount for applications in optoelectronics. Here we propose to pattern chemical vapor deposition grown graphene film through a stencil mask by magnetic-assisted ultraviolet (UV) ozonation under irradiation of a xenon excimer lamp. In this process, the paramagnetic oxygen molecules and photochemically generated oxygen radicals are magnetized and attracted in an inhomogenous external magnetic field...
April 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28422067/synthesis-characterization-antimicrobial-and-antiproliferative-activity-evaluation-of-cu-ii-co-ii-zn-ii-ni-ii-and-pt-ii-complexes-with-isoniazid-derived-compound
#11
Elena Pahonțu, Diana-Carolina Ilieș, Sergiu Shova, Camelia Oprean, Virgil Păunescu, Octavian Tudorel Olaru, Flavian Ștefan Rădulescu, Aurelian Gulea, Tudor Roșu, Doina Drăgănescu
Hydrazone complexes of Cu(II), Co(II), Zn(II), Ni(II) and Pt(II) with N-isonicotinoyl-N'-(3-metoxy-2 hydroxybenzaldehyde)-hydrazone (HL) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, as well as IR (infrared), ¹H-NMR and (13)C-NMR (hydrogen and carbon nuclear magnetic resonance, UV-Vis (ultraviolet-visible), FAB (fast atom bombardment), EPR (electron paramagnetic resonance), and mass spectroscopies...
April 19, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28421769/x-ray-absorption-and-electron-paramagnetic-resonance-guided-discovery-of-the-cu-catalyzed-synthesis-of-multiaryl-substituted-furans-from-aryl-styrene-and-ketones-using-dmso-as-the-oxidant
#12
Yong Wu, Zhiyuan Huang, Yi Luo, Dong Liu, Yi Deng, Hong Yi, Jyh-Fu Lee, Chih-Wen Pao, Jeng-Lung Chen, Aiwen Lei
The first example of DMSO serving not only as a solvent but also as an oxidant to promote the oxidation of Cu(I) to Cu(II) has been demonstrated. X-ray absorption and electron paramagnetic resonance evidence revealed a single-electron redox process where DMSO could oxidize Cu(I) to Cu(II). The novel discovery guided the rational design of copper-catalyzed oxidative cyclization of aryl ketones with styrenes to furans, providing a new method for the synthesis of multiaryl-substituted furans from cheap and readily available starting materials...
April 19, 2017: Organic Letters
https://www.readbyqxmd.com/read/28419595/lipopolysaccharide-lps-binding-to-the-periplasmic-protein-lpta
#13
Kathryn M Schultz, Tanner J Lundquist, Candice S Klug
Lipopolysaccharide (LPS) and the periplasmic protein LptA are two essential components of Gram-negative bacteria. LPS, also known as endotoxin, is found asymmetrically distributed in the outer leaflet of the outer membrane of Gram-negative bacteria such as Escherichia coli and plays a role in the organism's natural defenses in adverse environmental conditions. LptA is a member of the lipopolysaccharide transport protein (Lpt) family, which also includes LptC, LptDE, and LptBFG2 , that functions to transport LPS through the periplasm to the outer leaflet of the outer membrane after MsbA flips LPS across the inner membrane...
April 17, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28418260/fine-tuning-of-multicolored-photoluminescence-in-crystalline-magnetic-materials-constructed-of-trimetallic-euxtb1-x-co-cn-6-cyanido-bridged-chains
#14
Szymon Chorazy, Kunal Kumar, Koji Nakabayashi, Barbara Sieklucka, Shin-Ichi Ohkoshi
Coordination compounds built of trivalent lanthanide ions have been demonstrated as promising solid-state materials for diverse photoluminescent applications and as attractive magnetic objects with the prospective application in information storage and spintronics. We present a synthetic methodology in which both luminescent and magnetic functionalities are induced within lanthanide-based coordination polymers by the application of hexacyanocobaltate(III) anions and 3-hydroxypyridine (3-OHpy), both coordinated to 4f-metal ions modulating the lanthanide-centered properties...
April 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28418042/selective-orbital-reconstruction-in-tetragonal-fes-a-density-functional-dynamical-mean-field-theory-study
#15
Luis Craco, Stefano Leoni
Transport properties of tetragonal iron monosulfide, mackinawite, show a range of complex features. Semiconductive behavior and proximity to metallic states with nodal superconductivity mark this d-band system as unconventional quantum material. Here, we use the density functional dynamical mean-field theory (DFDMFT) scheme to comprehensively explain why tetragonal FeS shows both semiconducting and metallic responses in contrast to tetragonal FeSe which is a pseudogaped metal above the superconducting transition temperature...
April 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28415402/fattigation-platform-theranostic-nanoparticles-for-cancer-therapy
#16
Thao Truong-Dinh Tran, Phuong Ha-Lien Tran, Tae-Jong Yoon, Beom-Jin Lee
A new conceptual nanoparticle consisting of a silica-coated iron oxide magnetic core and a fattigation-based biocompatible shell with oleic acid and hydrophilic protein (gelatin). The prepared particle can be a useful theranostics platform material for diagnostic imaging and as a drug delivery system. Oleic acid and gelatin were conjugated on the silica-coated magnetic nanoparticle surface to provide three primary functionalities: 1) enhancing biocompatibility and solubility in aqueous solution and providing the ability to incorporate hydrophobic chemical drugs into the shell for delivery, 2) improving treatment-response magnetic monitoring as a diagnostic agent with low nanotoxicity, and 3) increasing anticancer efficacy owing to the controlled release of the incorporated drug in cells and in an animal model...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28415374/explicit-calculation-of-nuclear-magnetic-resonance-relaxation-rates-in-small-pores-to-elucidate-molecular-scale-fluid-dynamics
#17
D A Faux, P J McDonald
Nuclear-magnetic-resonance (NMR) spin-lattice (T_{1}^{-1}) and spin-spin (T_{2}^{-1}) relaxation rate measurements can act as effective nondestructive probes of the nanoscale dynamics of ^{1}H spins in porous media. In particular, fast-field-cycling T_{1}^{-1} dispersion measurements contain information on the dynamics of diffusing spins over time scales spanning many orders of magnitude. Previously published experimental T_{1}^{-1} dispersions from a plaster paste, synthetic saponite, mortar, and oil-bearing shale are reanalyzed using a model and associated theory which describe the relaxation rate contributions due to the interaction between spin ensembles in quasi-two-dimensional pores...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415296/nuclear-magnetic-resonance-relaxation-due-to-the-translational-diffusion-of-fluid-confined-to-quasi-two-dimensional-pores
#18
D A Faux, P J McDonald, N C Howlett
Nuclear-magnetic-resonance (NMR) relaxation experimentation is an effective technique for nondestructively probing the dynamics of proton-bearing fluids in porous media. The frequency-dependent relaxation rate T_{1}^{-1} can yield a wealth of information on the fluid dynamics within the pore provided data can be fit to a suitable spin diffusion model. A spin diffusion model yields the dipolar correlation function G(t) describing the relative translational motion of pairs of ^{1}H spins which then can be Fourier transformed to yield T_{1}^{-1}...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415285/ellipsoidal-brownian-self-driven-particles-in-a-magnetic-field
#19
Wai-Tong Louis Fan, On Shun Pak, Mario Sandoval
We study the two-dimensional Brownian dynamics of an ellipsoidal paramagnetic microswimmer moving at a low Reynolds number and subject to a magnetic field. Its corresponding mean-square displacement, showing the effect of a particles's shape, activity, and magnetic field on the microswimmer's diffusion, is analytically obtained. Comparison between analytical and computational results shows good agreement. In addition, the effect of self-propulsion on the transition time from anisotropic to isotropic diffusion of the ellipse is investigated...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28414431/mononuclear-sulfido-tungsten-v-complexes-completing-the-tp-mexy-m-mo-w-e-o-s-series
#20
Stephen Sproules, Aston A Eagle, Graham N George, Jonathan M White, Charles G Young
Orange Tp*WSCl2 has been synthesized from the reactions of Tp*WOCl2 with boron sulfide in refluxing toluene or Tp*WS2Cl with PPh3 in dichloromethane at room temperature. Mononuclear sulfido-tungsten(V) complexes, Tp*WSXY {X = Y = Cl, OPh, SPh, SePh; X = Cl, Y = OPh; XY = toluene-3,4-dithiolate (tdt), quinoxaline-2,3-dithiolate (qdt); and Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate} were prepared by metathesis of Tp*WSCl2 with the respective alkali metal salt of X(-)/XY(2-), or [NHEt3]2(qdt). The complexes were characterized by microanalysis, mass spectrometry, electrochemistry, and infrared (IR), electron paramagnetic resonance (EPR) and electronic absorption spectroscopies...
April 17, 2017: Inorganic Chemistry
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