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https://www.readbyqxmd.com/read/28088759/how-accurate-are-accurate-force-fields-for-b-dna
#1
Pablo D Dans, Ivan Ivani, Adam Hospital, Guillem Portella, Carlos González, Modesto Orozco
Last generation of force-fields are raising expectations on the quality of molecular dynamics (MD) simulations of DNA, as well as to the belief that theoretical models can substitute experimental ones in several cases. However these claims are based on limited benchmarks, where MD simulations have shown the ability to reproduce already existing 'experimental models', which in turn, have an unclear accuracy to represent DNA conformation in solution. In this work we explore the ability of different force-fields to predict the structure of two new B-DNA dodecamers, determined herein by means of (1)H nuclear magnetic resonance (NMR)...
January 13, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28088483/physiology-recording-with-magnetic-field-probes-for-fmri-denoising
#2
Simon Gross, Laetitia Vionnet, Lars Kasper, Benjamin E Dietrich, Klaas P Pruessmann
Physiological noise originating in cardiovascular and respiratory processes is a substantial confound in BOLD fMRI. When unaccounted for it reduces the temporal SNR and causes error in inferred brain activity and connectivity. Physiology correction typically relies on auxiliary measurements with peripheral devices such as ECG, pulse oximeters, and breathing belts. These require direct skin contact or at least a tight fit, impairing subject comfort and adding to the setup time. In this work, we explore a touch-free alternative for physiology recording, using magnetic detection with NMR field probes...
January 11, 2017: NeuroImage
https://www.readbyqxmd.com/read/28088162/molecular-collisions-and-reactive-scattering-in-external-fields-are-field-induced-couplings-important-at-short-range
#3
D Vieira, R V Krems, T V Tscherbul
We use accurate quantum scattering calculations to elucidate the role of short-range molecule-field interactions in atom-molecule inelastic collisions and abstraction chemical reactions at low temperatures. We consider two examples: elastic and inelastic scattering of NH(Σ3) molecules with Mg(S1) atoms in a magnetic field; reactive scattering LiF + H → Li + HF in an electric field. Our calculations suggest that, for non-reactive collision systems and abstraction chemical reactions, the molecule-field interactions cannot generally be neglected at short range because the atom-molecule potential passes through zero at short range...
January 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28081561/a-novel-richardson-lucy-model-with-dictionary-basis-and-spatial-regularization-for-isolating-isotropic-signals
#4
Tiantian Xu, Yuanjing Feng, Ye Wu, Qingrun Zeng, Jun Zhang, Jianzhong He, Qichuan Zhuge
Diffusion-weighted magnetic resonance imaging is a non-invasive imaging method that has been increasingly used in neuroscience imaging over the last decade. Partial volume effects (PVEs) exist in sampling signal for many physical and actual reasons, which lead to inaccurate fiber imaging. We overcome the influence of PVEs by separating isotropic signal from diffusion-weighted signal, which can provide more accurate estimation of fiber orientations. In this work, we use a novel response function (RF) and the correspondent fiber orientation distribution function (fODF) to construct different signal models, in which case the fODF is represented using dictionary basis function...
2017: PloS One
https://www.readbyqxmd.com/read/28081452/differential-white-matter-involvement-associated-with-distinct-visuospatial-deficits-after-right-hemisphere-stroke
#5
Alex R Carter, Mark P McAvoy, Joshua S Siegel, Xin Hong, Serguei V Astafiev, Jennifer Rengachary, Kristi Zinn, Nicholas V Metcalf, Gordon L Shulman, Maurizio Corbetta
Visuospatial attention depends on the integration of multiple processes, and people with right hemisphere lesions after a stroke may exhibit severe or no visuospatial deficits. The anatomy of core components of visuospatial attention is an area of intense interest. Here we examine the relationship between the disruption of core components of attention and lesion distribution in a heterogeneous group (N = 70) of patients with right hemisphere strokes regardless of the presence of clinical neglect. Deficits of lateralized spatial orienting, measured as the difference in reaction times for responding to visual targets in the contralesional or ipsilesional visual field, and deficits in re-orienting attention, as measured by the difference in reaction times for invalidly versus validly cued targets, were measured using a computerized spatial orienting task...
December 20, 2016: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28081239/statistical-modeling-applied-to-deformation-relaxation-processes-in-a-composite-biopolymer-network-induced-by-magnetic-field
#6
Javier Tarrío-Saavedra, Cécilia Galindo González, Salvador Naya, Jorge López-Beceiro, Alain Ponton
This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling...
2017: PloS One
https://www.readbyqxmd.com/read/28081199/mesons-from-laser-induced-processes-in-ultra-dense-hydrogen-h-0
#7
Leif Holmlid
Large signals of charged light mesons are observed in the laser-induced particle flux from ultra-dense hydrogen H(0) layers. The mesons are formed in such layers on metal surfaces using < 200 mJ laser pulse-energy. The time variation of the signal to metal foil collectors and the magnetic deflection to a movable pin collector are now studied. Relativistic charged particles with velocity up to 500 MeV u-1 thus 0.75 c are observed. Characteristic decay time constants for meson decay are observed, for charged and neutral kaons and also for charged pions...
2017: PloS One
https://www.readbyqxmd.com/read/28081157/simultaneous-quantitative-mri-mapping-of-t1-t2-and-magnetic-susceptibility-with-multi-echo-mp2rage
#8
Riccardo Metere, Tobias Kober, Harald E Möller, Andreas Schäfer
The knowledge of relaxation times is essential for understanding the biophysical mechanisms underlying contrast in magnetic resonance imaging. Quantitative experiments, while offering major advantages in terms of reproducibility, may benefit from simultaneous acquisitions. In this work, we demonstrate the possibility of simultaneously recording relaxation-time and susceptibility maps with a prototype Multi-Echo (ME) Magnetization-Prepared 2 RApid Gradient Echoes (MP2RAGE) sequence. T1 maps can be obtained using the MP2RAGE sequence, which is relatively insensitive to inhomogeneities of the radio-frequency transmit field, [Formula: see text]...
2017: PloS One
https://www.readbyqxmd.com/read/28081101/design-of-many-body-spin-states-of-rydberg-atoms-excited-to-highly-tunable-magnetic-sublevels
#9
Svetlana A Malinovskaya
Quantum control methodology is presented to design many-body spin states in a spin chain of Rydberg atoms using laser pulses and a magnetic field. A two-photon ladder-type configuration is implemented, which is advantageous due to the combined action of the one-photon and two-photon detunings as control parameters. Many-body spin states are designed consisting of an ensemble of spins encoded in sublevels of Rydberg states and coupled via the van der Waals interactions.
January 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28081017/lattice-parameters-guide-superconductivity-in-iron-arsenides
#10
Lance M N Konzen, Athena S Sefat
The discovery of superconducting materials has led to their use in technological marvels such as magnetic-field sensors in MRI machines, powerful research magnets, short transmission cables, and high-speed trains. Despite such applications, the uses of superconductors are not widespread because they function much below room-temperature, hence the costly cooling. Since the discovery of Cu- and Fe-based high-temperature superconductors (HTS), much intense effort has tried to explain and understand the superconducting phenomenon...
January 12, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28081013/magneto-photoluminescence-measurements-of-tungsten-disulphide-monolayers
#11
Jan Kuhnert, Arash Rahimi-Iman, Wolfram Heimbrodt
Layered transition-metal dichalcogenides have attracted great interest in the last few years. Thinned down to the monolayer limit they change from an indirect band structure to a direct band gap in the visible region. Due to the monolayer thickness the inversion symmetry of the crystal is broken and spin and valley are coupled to each other. The degeneracy between the two equivalent valleys, K and K', respectively, can be lifted by applying an external magnetic field. Here, we present photoluminescence measurements of CVD-grown tungsten disulphide (WS2) monolayers at temperatures of 2 K...
January 12, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28081012/the-lead-acceptor-in-p-type-natural-2h-polytype-mos2-crystals-evidenced-by-electron-paramagnetic-resonance
#12
S Iacovo, A Stesmans, M Houssa, V V Afanas'ev
A low-temperature (T  =  1.5-8 K) electron paramagnetic resonance study of p-type 2H-polytype natural MoS2 crystals reveals a previously unreported anisotropic signal of corresponding defect density (spin S  =  ½) ~5  ×  10(14) cm(-3). For the applied magnetic field B//c-axis, the response is comprised of a single central asymmetric Zeeman peak at zero-crossing g  =  2.102(1), amid a symmetrically positioned hyperfine doublet of splitting 6.6(2) G. Field angular observations reveal a two-branch g pattern, indicative of a defect of lower than axial symmetry, likely orthorhombic (C 2v)...
January 12, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28080044/structural-dependence-of-the-ising-type-magnetic-anisotropy-and-of-the-relaxation-time-in-mononuclear-trigonal-bipyramidal-co-ii-single-molecule-magnets
#13
Feng Shao, Benjamin Cahier, Eric Rivière, Régis Guillot, Nathalie Guihéry, Victoria E Campbell, Talal Mallah
This paper describes the correlation between Ising-type magnetic anisotropy and structure in trigonal bipyramidal Co(II) complexes. Three sulfur-containing trigonal bipyramidal Co(II) complexes were synthesized and characterized. It was shown that we can engineer the magnitude of the Ising anisotropy using ligand field theory arguments in conjunction with structural parameters. To prepare this series of compounds, we used, on the one hand, a tetradentate ligand containing three sulfur atoms and one amine (NS3(tBu)) and on the other hand three different axial ligands, namely, Cl(-), Br(-), and NCS(-)...
January 12, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28079975/edge-states-and-topological-phase-transitions-in-chains-of-dielectric-nanoparticles
#14
Sergey Kruk, Alexey Slobozhanyuk, Denitza Denkova, Alexander Poddubny, Ivan Kravchenko, Andrey Miroshnichenko, Dragomir Neshev, Yuri Kivshar
Recently introduced field of topological photonics aims to explore the concepts of topological insulators for novel phenomena in optics. Here polymeric chains of subwavelength silicon nanodisks are studied and it is demonstrated that these chains can support two types of topological edge modes based on magnetic and electric Mie resonances, and their topological properties are fully dictated by the spatial arrangement of the nanoparticles in the chain. It is observed experimentally and described how theoretically topological phase transitions at the nanoscale define a change from trivial to nontrivial topological states when the edge mode is excited...
January 12, 2017: Small
https://www.readbyqxmd.com/read/28079303/mononuclear-clusterfullerene-single-molecule-magnet-containing-strained-fused-pentagons-stabilized-by-a-nearly-linear-metal-cyanide-cluster
#15
Fupin Liu, Song Wang, Cong-Li Gao, Qingming Deng, Xianjun Zhu, Aram Kostanyan, Rasmus Westerström, Fei Jin, Su-Yuan Xie, Alexey A Popov, Thomas Greber, Shangfeng Yang
Fused-pentagons results in an increase of local steric strain according to the isolated pentagon rule (IPR), and for all reported non-IPR clusterfullerenes multiple (two or three) metals are required to stabilize the strained fused-pentagons, making it difficult to access the single-atom properties. Herein, we report the syntheses and isolations of novel non-IPR mononuclear clusterfullerenes MNC@C76 (M=Tb, Y), in which one pair of strained fused-pentagon is stabilized by a mononuclear cluster. The molecular structures of MNC@C76 (M=Tb, Y) were determined unambiguously by single-crystal X-ray diffraction, featuring a non-IPR C2v (19138)-C76 cage entrapping a nearly linear MNC cluster, which is remarkably different from the triangular MNC cluster within the reported analogous clusterfullerenes based on IPR-obeying C82 cages...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28079264/electromagnetic-computation-and-modeling-in-mri
#16
REVIEW
Xin Chen, Michael Steckner
Electromagnetic (EM) computational modeling is used extensively during the development of a Magnetic Resonance Imaging (MRI) scanner, its installation, and use. MRI, which relies on interactions between nuclear magnetic moments and the applied magnetic fields, uses a range of EM tools to optimize all of the magnetic fields required to produce the image. The main field magnet is designed to exacting specifications but challenges in manufacturing, installation, and use require additional tools to maintain target operational performance...
January 12, 2017: Medical Physics
https://www.readbyqxmd.com/read/28079117/high-field-transport-properties-of-a-p-doped-bafe2as2-film-on-technical-substrate
#17
Kazumasa Iida, Hikaru Sato, Chiara Tarantini, Jens Hänisch, Jan Jaroszynski, Hidenori Hiramatsu, Bernhard Holzapfel, Hideo Hosono
High temperature (high-Tc) superconductors like cuprates have superior critical current properties in magnetic fields over other superconductors. However, superconducting wires for high-field-magnet applications are still dominated by low-Tc Nb3Sn due probably to cost and processing issues. The recent discovery of a second class of high-Tc materials, Fe-based superconductors, may provide another option for high-field-magnet wires. In particular, AEFe2As2 (AE: Alkali earth elements, AE-122) is one of the best candidates for high-field-magnet applications because of its high upper critical field, Hc2, moderate Hc2 anisotropy, and intermediate Tc...
January 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28079028/observation-of-ultrasharp-metamagnetic-jumps-in-polycrystalline-er2cu2o5
#18
Anupam Banerjee, Jhuma Sannigrahi, Saurav Giri, Subham Majumdar
The observation of ultrasharp metamagnetic jumps in the field variation of magnetization ($M$ versus $H$) data of the highly insulating metal oxide Er$_2$Cu$_2$O$_5$ is investigated. The compound orders antiferromagnetically below about $T_{N1}$ = 28 K and shows conventional `not-so-sharp' metamagnetism around 13 kOe on the field increasing leg in the polycrystalline sample. The uniqueness of the ultrasharp jumps in Er$_2$Cu$_2$O$_5$ is that it is only observed in the field decreasing segment of the magnetization curve...
January 12, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28078913/silibinin-loaded-magnetic-nanoparticles-inhibit-htert-gene-expression-and-proliferation-of-lung-cancer-cells
#19
Soumaye Amirsaadat, Younes Pilehvar-Soltanahmadi, Faraz Zarghami, Shahriar Alipour, Zohreh Ebrahimnezhad, Nosratollah Zarghami
Nanoparticle-based targeted drug delivery has the potential for rendering silibinin specifically at the favorite site using an external magnetic field. Also, it can circumvent the pitfalls of poor solubility. For this purpose, silibinin-loaded magnetic nanoparticles are fabricated, characterized and evaluated cytotoxicity and hTERT gene expression in A549 lung cancer cell line. silibinin-loaded PLGA-PEG-Fe3O4 had dose- and time-dependent cytotoxicity than pure silibinin. Additionally, hTERT expression is more efficiently reduced with increasing concentrations of nanosilibinin than pure silibinin...
January 12, 2017: Artificial Cells, Nanomedicine, and Biotechnology
https://www.readbyqxmd.com/read/28078855/the-impact-of-electromagnetic-field-at-a-frequency-of-50-hz-and-a-magnetic-induction-of-2-5-mt-on-viability-of-pineal-cells-in-vitro
#20
A Koziorowska, E Pasiud, M Fila, M Romerowicz-Misielak
The impact of electromagnetic fields (EMF) on the pineal gland has been described in numerous studies, but many questions still remain unanswered. The aim of the experiment described in this study was to evaluate the effect of EMF on the viability of the pineal gland cells of pig in vitro. Primary culture of the pineal gland cells has been exposed to the influence of an EMF at a frequency of 50 Hz with 1, 2 or 3 hours and for 3 hours every 2 or 3 days. After the experiment, viability of cells was assessed by MTT assay and compared to a control culture not exposed to electromagnetic fields...
October 2016: Journal of Biological Regulators and Homeostatic Agents
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