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https://www.readbyqxmd.com/read/27920435/evolution-of-the-intrinsic-electronic-phase-separation-in-la0-6er0-1sr0-3mno3-perovskite
#1
Lili Chen, Jiyu Fan, Wei Tong, Dazhi Hu, Yanda Ji, Jindong Liu, Lei Zhang, Li Pi, Yuheng Zhang, Hao Yang
Magnetic and electronic transport properties of perovskite manganite La0.6Er0.1Sr0.3MnO3 have been thoroughly examined through the measurements of magnetization, electron paramagnetic resonance(EPR), and resistivity. It was found that the substitution of Er(3+) for La(3+) ions introduced the chemical disorder and additional strain in this sample. An extra resonance signal occurred in EPR spectra at high temperatures well above T C gives a strong evidence of electronic phase separation(EPS). The analysis of resistivity enable us to identify the polaronic transport mechanism in the paramagnetic region...
December 2016: Scientific Reports
https://www.readbyqxmd.com/read/27918930/paramagnetic-solid-state-nmr-of-materials
#2
REVIEW
Marko Bertmer
Solid-state NMR (SSNMR) experiments are mainly performed on diamagnetic materials. However, the study of paramagnetic materials offers access to additional information in combination with the unpaired electron. This article discusses the experimental complications arising when considering paramagnetic materials such as large shift effects and large linewidths. A look at the theoretical description as well as experimental methods are shown and accompanied by techniques for signal assignment, also with the help of quantum-chemical calculations...
November 9, 2016: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/27918126/versatile-trityl-spin-labels-for-nanometer-distance-measurements-on-biomolecules-in%C3%A2-vitro-and-within-cells
#3
J Jacques Jassoy, Andreas Berndhäuser, Fraser Duthie, Sebastian P Kühn, Gregor Hagelueken, Olav Schiemann
Structure determination of biomacromolecules under in-cell conditions is a relevant yet challenging task. Electron paramagnetic resonance (EPR) distance measurements in combination with site-directed spin labeling (SDSL) are a valuable tool in this endeavor but the usually used nitroxide spin labels are not well-suited for in-cell measurements. In contrast, triarylmethyl (trityl) radicals are highly persistent, exhibit a long relaxation time and a narrow spectral width. Here, the synthesis of a versatile collection of trityl spin labels and their application in in vitro and in-cell trityl-iron distance measurements on a cytochrome P450 protein are described...
December 5, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27918029/probing-the-role-of-the-backbone-carbonyl-interaction-with-the-cua-center-in-azurin-by-replacing-the-peptide-bond-with-an-ester-linkage
#4
Kevin M Clark, Shiliang Tian, Wilfred A van der Donk, Yi Lu
The role of a backbone carbonyl interaction with an engineered CuA center in azurin was investigated by developing a method of synthesis and incorporation of a depsipeptide where one of the amide bonds in azurin is replaced by an ester bond using expressed protein ligation. Studies by electronic absorption and electron paramagnetic resonance spectroscopic techniques indicate that, while the substitution does not significantly alter the geometry of the site, it weakens the axial interaction to the CuA center and strengthens the Cu-Cu bond, as evidenced by the blue shift of the near-IR absorption that has been assigned to the Cu-Cu ψ → ψ* transition...
December 5, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27918022/a-systematic-study-of-25-mg-nmr-in-paramagnetic-transition-metal-oxides-applications-to-mg-ion-battery-materials
#5
Jeongjae Lee, Ieuan D Seymour, Andrew J Pell, Siân E Dutton, Clare P Grey
Rechargeable battery systems based on Mg-ion chemistries are generating significant interest as potential alternatives to Li-ion batteries. Despite the wealth of local structural information that could potentially be gained from Nuclear Magnetic Resonance (NMR) experiments of Mg-ion battery materials, systematic (25)Mg solid-state NMR studies have been scarce due to the low natural abundance, low gyromagnetic ratio, and significant quadrupole moment of (25)Mg (I = 5/2). This work reports a combined experimental (25)Mg NMR and first principles density functional theory (DFT) study of paramagnetic Mg transition metal oxide systems Mg6MnO8 and MgCr2O4 that serve as model systems for Mg-ion battery cathode materials...
December 5, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27917865/critical-exponents-and-scaling-invariance-in-the-absence-of-a-critical-point
#6
N Saratz, D A Zanin, U Ramsperger, S Cannas, D Pescia, A Vindigni
The paramagnetic-to-ferromagnetic phase transition is classified as a critical phenomenon due to the power-law behaviour shown by thermodynamic observables when the Curie point is approached. Here we report the observation of such a behaviour over extraordinarily many decades of suitable scaling variables in ultrathin Fe films, for certain ranges of temperature T and applied field B. This despite the fact that the underlying critical point is practically unreachable because protected by a phase with a modulated domain structure, induced by the dipole-dipole interaction...
December 5, 2016: Nature Communications
https://www.readbyqxmd.com/read/27915179/axially-uniform-magnetic-field-modulation-excitation-for-electron-paramagnetic-resonance-in-rectangular-and-cylindrical-cavities-by-slot-cutting
#7
Jason W Sidabras, James E Richie, James S Hyde
In continuous-wave (CW) Electron Paramagnetic Resonance (EPR) a low-frequency time-harmonic magnetic field, called field modulation, is applied parallel to the static magnetic field and incident on the sample. Varying amplitude of the field modulation incident on the sample has consequences on spectral line-shape and line-height over the axis of the sample. Here we present a method of coupling magnetic field into the cavity using slots perpendicular to the sample axis where the slot depths are designed in such a way to produce an axially uniform magnetic field along the sample...
November 25, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/27915178/anticancer-copper-pyridine-benzimidazole-complexes-ros-generation-biomolecule-interactions-and-cytotoxicity
#8
Kathleen E Prosser, Stephanie W Chang, Felix Saraci, Phuc H Le, Charles J Walsby
The Cu(II) complex CuCl2(pbzH), pbzH=2-(2-pyridyl)benzimidazole, and derivatives modified at the non-coordinated nitrogen of the benzimidazole fragment, have been studied as anticancer agents. These compounds show promising cytotoxicity against A549 adenocarcinomic alveolar basal epithelial cells with IC50 values in the range of 5-10μM. Importantly, this activity is higher than either CuCl2·2H2O or the individual ligands, demonstrating that ligand coordination to the Cu(II) centres of the complexes is required for full activity...
November 5, 2016: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/27911811/the-structure-of-the-catechin-binding-site-of-human-sulfotransferase-1a1
#9
Ian Cook, Ting Wang, Mark Girvin, Thomas S Leyh
We are just beginning to understand the allosteric regulation of the human cytosolic sulfotransferase (SULTs) family-13 disease-relevant enzymes that regulate the activities of hundreds, if not thousands, of signaling small molecules. SULT1A1, the predominant isoform in adult liver, harbors two noninteracting allosteric sites, each of which binds a different molecular family: the catechins (naturally occurring flavonols) and nonsteroidal antiinflammatory drugs (NSAIDs). Here, we present the structure of an SULT allosteric binding site-the catechin-binding site of SULT1A1 bound to epigallocatechin gallate (EGCG)...
November 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27911517/universal-signatures-of-quantum-critical-points-from-finite-size-torus-spectra-a-window-into-the-operator-content-of-higher-dimensional-conformal-field-theories
#10
Michael Schuler, Seth Whitsitt, Louis-Paul Henry, Subir Sachdev, Andreas M Läuchli
The low-energy spectra of many body systems on a torus, of finite size L, are well understood in magnetically ordered and gapped topological phases. However, the spectra at quantum critical points separating such phases are largely unexplored for (2+1)D systems. Using a combination of analytical and numerical techniques, we accurately calculate and analyze the low-energy torus spectrum at an Ising critical point which provides a universal fingerprint of the underlying quantum field theory, with the energy levels given by universal numbers times 1/L...
November 18, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27911291/a-metal-free-method-for-producing-mri-contrast-at-amyloid-%C3%AE
#11
Silvia Hilt, Tang Tang, Jeffrey H Walton, Madhu Budamagunta, Izumi Maezawa, Tamás Kálai, Kálmán Hideg, Vikrant Singh, Heike Wulff, Qizhi Gong, Lee-Way Jin, Angelique Louie, John C Voss
Alzheimer's disease (AD) is characterized by depositions of the amyloid-β (Aβ) peptide in the brain. The disease process develops over decades, with substantial neurological loss occurring before a clinical diagnosis of dementia can be rendered. It is therefore imperative to develop methods that permit early detection and monitoring of disease progression. In addition, the multifactorial pathogenesis of AD has identified several potential avenues for AD intervention. Thus, evaluation of therapeutic candidates over lengthy trial periods also demands a practical, noninvasive method for measuring Aβ in the brain...
November 26, 2016: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/27910780/naringenin-ameliorates-doxorubicin-toxicity-and-hypoxic-condition-in-dalton-s-lymphoma-ascites-tumor-mouse-model-evidence-from-electron-paramagnetic-resonance-imaging
#12
Venkatesan Kathiresan, Swathika Subburaman, Arun Venkatesh Krishna, Mathivanan Natarajan, Gandhidasan Rathinasamy, Kumaresan Ganesan, Murugesan Ramachandran
Doxorubicin (DOX) is a well-known cytotoxic agent used extensively as a chemotherapeutic drug to eradicate a wide variety of human cancers. Reactive oxygen species (ROS)-mediated oxidative stress during DOX treatment can induce cardiac, renal, and hepatic toxicities, which can constrain its use as a potential cytotoxic agent. The present work investigates the antioxidant potential of naringenin (NAR) against DOXinduced toxicities of a Dalton's lymphoma ascites (DLA) tumor-bearing mouse model. Mice were randomized into four groups: a negative control, positive control, DOX (2...
2016: Journal of Environmental Pathology, Toxicology and Oncology
https://www.readbyqxmd.com/read/27907864/heterolytic-oo-bond-cleavage-functional-role-of-glu113-during-bis-fe-iv-formation-in-maug
#13
Jiafeng Geng, Lu Huo, Aimin Liu
The diheme enzyme MauG utilizes H2O2 to perform oxidative posttranslational modification on a protein substrate. A bis-Fe(IV) species of MauG was previously identified as a key intermediate in this reaction. Heterolytic cleavage of the OO bond of H2O2 drives the formation of the bis-Fe(IV) intermediate. In this work, we tested a hypothesis that a glutamate residue, Glu113 in the distal pocket of the pentacoordinate heme of MauG, facilitates heterolytic OO bond cleavage, thereby leading to bis-Fe(IV) formation...
November 9, 2016: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/27905523/test-of-quantum-thermalization-in-the-two-dimensional-transverse-field-ising-model
#14
Benjamin Blaß, Heiko Rieger
We study the quantum relaxation of the two-dimensional transverse-field Ising model after global quenches with a real-time variational Monte Carlo method and address the question whether this non-integrable, two-dimensional system thermalizes or not. We consider both interaction quenches in the paramagnetic phase and field quenches in the ferromagnetic phase and compare the time-averaged probability distributions of non-conserved quantities like magnetization and correlation functions to the thermal distributions according to the canonical Gibbs ensemble obtained with quantum Monte Carlo simulations at temperatures defined by the excess energy in the system...
December 1, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27905382/-complexes-of-nitric-oxide-with-hemoglobin-and-paramagnetic-metalloenzymes-in-the-brain-and-blood-of-mammals-after-intermittent-hypoxia
#15
Z V Kuropteva, V P Reutov, L M Baider, A L Krushinsky
AIM: To investigate an effect of hypoxia on the formation of nitric oxide (NO) in the brain and blood of rats and an influence of L-NNA, the NO-synthase inhibitor, and sodium nitrite on NO generation in separate and simultaneous introduction of these compounds in the animal body. MATERIAL AND METHODS: Experiments were conducted on 42 rats of Krushinsky-Molodkina (K-M) line without adaptation to hypoxia and short-term adaptation to hypobaric hypoxia. Animals were intraperitoneally injected with sodium nitrite (0...
2016: Zhurnal Nevrologii i Psikhiatrii Imeni S.S. Korsakova
https://www.readbyqxmd.com/read/27901150/correlation-of-dielectric-electrical-and-magnetic-properties-near-the-magnetic-phase-transition-temperature-of-cobalt-zinc-ferrite
#16
Dhiren K Pradhan, Shalini Kumari, Venkata S Puli, Proloy T Das, Dillip K Pradhan, Ashok Kumar, J F Scott, Ram S Katiyar
Multiferroic composite structures, i.e., composites of magnetostrictive and piezoelectric materials, can be envisioned to achieve the goal of strong room-temperature ME coupling for real practical device applications. Magnetic materials with high magnetostriction, high Néel temperature (TN), high resistivity and large magnetization are required to observe high ME coupling in composite structures. In continuation of our investigations on suitable magnetic candidates for multiferroic composite structures, we have studied the crystal structure, dielectric, transport, and magnetic properties of Co0...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27898372/gamma-radiation-induced-thermoluminescence-trace-element-and-paramagnetic-defect-of-quartz-from-the-sambagawa-metamorphic-belt-central-shikoku-japan
#17
T Chuenpee, O Nishikawa, Y Kon, K Ninagawa, S Toyoda, T Ogata, T Uchida, I Takashima
This study analyzes the Thermoluminescence (TL) emissions for five emission bands, trace element concentrations and defects in quartz grains extracted from metamorphic rocks and quartz veins in the Sambagawa metamorphic belt, central Shikoku. An emission of 500nm with 195, 245, and 320-325°C glow peaks are observed through the lowest to highest grade samples. A 450nm emission band with intense 195 and 245°C glow peaks and a 320-325°C shoulder peak is found in the higher grade samples. A 570nm emission band with a 170°C glow peak is observed in the samples derived from the lower grade zones...
November 17, 2016: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/27897355/aqueous-eu-ii-oxidation-rate-tuned-by-coordination-environment
#18
Levi A Ekanger, Lina A Basal, Matthew John Allen
The Eu(II/III) redox couple offers metal-based oxidation-sensing with magnetic resonance imaging making the study of Eu(II) oxidation chemistry important in the design of new probes. Accordingly, we explored oxidation reactions with a set of Eu(II)-containing complexes. We report the observation of superoxide formation from the reaction between Eu(II) and dioxygen using electron paramagnetic resonance spectroscopy. Additionally, we report oxidation kinetics of three Eu(II)-containing complexes with bromate and glutathione disulfide at pH values including 5 and 7...
November 29, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27897163/direct-visualization-of-a-fe-iv-oh-intermediate-in-a-heme-enzyme
#19
Hanna Kwon, Jaswir Basran, Cecilia M Casadei, Alistair J Fielding, Tobias E Schrader, Andreas Ostermann, Juliette M Devos, Pierre Aller, Matthew P Blakeley, Peter C E Moody, Emma L Raven
Catalytic heme enzymes carry out a wide range of oxidations in biology. They have in common a mechanism that requires formation of highly oxidized ferryl intermediates. It is these ferryl intermediates that provide the catalytic engine to drive the biological activity. Unravelling the nature of the ferryl species is of fundamental and widespread importance. The essential question is whether the ferryl is best described as a Fe(IV)=O or a Fe(IV)-OH species, but previous spectroscopic and X-ray crystallographic studies have not been able to unambiguously differentiate between the two species...
November 29, 2016: Nature Communications
https://www.readbyqxmd.com/read/27896733/3d-computational-modeling-of-proteins-using-sparse-paramagnetic-nmr-data
#20
Kala Bharath Pilla, Gottfried Otting, Thomas Huber
Computational modeling of proteins using evolutionary or de novo approaches offers rapid structural characterization, but often suffers from low success rates in generating high quality models comparable to the accuracy of structures observed in X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. A computational/experimental hybrid approach incorporating sparse experimental restraints in computational modeling algorithms drastically improves reliability and accuracy of 3D models. This chapter discusses the use of structural information obtained from various paramagnetic NMR measurements and demonstrates computational algorithms implementing pseudocontact shifts as restraints to determine the structure of proteins at atomic resolution...
2017: Methods in Molecular Biology
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