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https://www.readbyqxmd.com/read/28938135/bang-bang-optimal-control-of-large-spin-systems-enhancement-of-13-c-13-c-singlet-order-at-natural-abundance
#1
Deepak Khurana, T S Mahesh
Using a bang-bang optimal control technique, we transfer polarization from a set of abundant high-γ nuclei directly to singlet order of a low-γ spin-pair. This approach is analogous to algorithmic cooling (AC) procedure used in quantum state purification. Specifically, we apply this method for enhancing the singlet order in a natural abundant (13)C- (13)C spin pair by exploiting nine equivalent protons of an 11-spin system. Compared to the standard method not involving polarization transfer, we find an enhancement of singlet order by about 3...
September 14, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28938134/long-lived-states-detect-interactions-between-small-molecules-and-diamagnetic-metal-ions
#2
Cristina Stavarache, Anamaria Hanganu, Anca Paun, Codruta Paraschivescu, Mihaela Matache, Paul R Vasos
Long-lived states of nuclear spin order were used for the first time to probe interactions between molecules and diamagnetic metal ions. Proton spin states with lifetimes twice as long as the spin-lattice relaxation time constants of the same nuclei were promoted on the methoxyphenyl and tolyl substituents of a 1,3,4-oxadiazole derivative. The transient interaction of this oxadiazole derivative with silver(I) ions significantly speeds up the relaxation rate constants of proton long-lived states. The interactions between silver and organic compounds lead to the formation of coordination polymers that can be used for the preparation of bio-compatible materials...
September 6, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28938068/direct-patterning-of-zinc-sulfide-on-a-sub-10-nanometer-scale-via-electron-beam-lithography
#3
Mohammad S M Saifullah, Mohamed Asbahi, Maryam Binti-Kamran Kiyani, Sudhiranjan Tripathy, Esther A H Ong, Asadullah Ibn Saifullah, Hui Ru Tan, Tanmay Dutta, Ramakrishnan Ganesan, Suresh Valiyaveettil, Karen Siew-Ling Chong
Nanostructures of metal sulfides are conventionally prepared via chemical techniques and patterned using self-assembly. This poses a considerable amount of challenge when arbitrary shapes and sizes of nanostructures are desired to be placed at precise locations. Here we describe an alternative approach of nanoscale patterning of zinc sulfide (ZnS) directly using a spin-coatable and electron beam-sensitive zinc butylxanthate resist without the lift-off or etching step. Time-resolved electron beam damage studies using micro-Raman and micro-FTIR spectroscopies suggest that exposure to a beam of electrons lead to quick disappearance of xanthate moieties most likely via the Chugaev elimination, and further increase of electron dose results in the appearance of ZnS, thereby making the exposed resist insoluble in organic solvents...
September 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28937756/direct-comparison-of-c-h-bond-amination-efficacy-through-manipulation-of-nitrogen-valence-centered-redox-imido-versus-iminyl
#4
Matthew J T Wilding, Diana A Iovan, Alexandra T Wrobel, James T Lukens, Samantha N MacMillan, Kyle M Lancaster, Theodore A Betley
Reduction of previously reported iminyl radical (ArL)FeCl(•N(C6H4-p-tBu)) (2) with potassium graphite furnished the corresponding high-spin (S = 5/2) imido (ArL)Fe(N(C6H4-p-tBu)) (3) (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin). Oxidation of the three-coordinate imido (ArL)Fe(NAd) (5) with chlorotriphenylmethane afforded (ArL)FeCl(•NAd) (6) with concomitant expulsion of Ph3C(C6H5)CPh2. The respective alkyl/aryl imido/iminyl pairs (3, 2; 5, 6) have been characterized by EPR, zero-field 57Fe Mössbauer, magnetometry, single crystal X-ray diffraction, XAS, and EXAFS for 6...
September 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28937745/mononuclear-fe-ii-complexes-based-on-the-methylpyrazinyl-diamine-ligand-chemical-thermo-and-photocontrol-of-their-magnetic-switchability
#5
Xue Liu, Jian Zhou, Xin Bao, Zheng Yan, Guo Peng, Mathieu Rouzières, Corine Mathonière, Jun-Liang Liu, Rodolphe Clérac
Two new mononuclear Fe(II) complexes, [Fe((2Me)Lpz)(NCX)2] (L = N,N'-dimethyl-N,N'-bis((pyrazin-2-yl)methyl)-1,2-ethanediamine and X = S (1), BH3 (2)), have been synthesized and characterized by single-crystal X-ray diffraction, magnetic, optical reflectivity, and photomagnetic measurements. They have similar FeN6 coordination environments offered by the tetradentate ligand with a cis-α conformation and two NCX(-) coligands in cis positions. However, 1 and 2 have different molecular arrangements and crystal packings, and are isolated in orthorhombic Pbnb and monoclinic C2/c space groups, respectively...
September 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28937744/methane-c-h-activation-via-3d-metal-methoxide-complexes-with-potentially-redox-noninnocent-pincer-ligands-a-density-functional-theory-study
#6
Ahmad Najafian, Thomas R Cundari
This paper reports a density functional theory study of 3d transition-metal methoxide complexes with potentially redox-noninnocent pincer supporting ligands for methane C-H bond activation to form methanol (LnM-OMe + CH4 → LnM-Me + CH3OH). The three types of tridentate pincer ligands [terpyridine (NNN), bis(2-pyridyl)phenyl-C,N,N' (NCN), and 2,6-bis(2-phenyl)pyridine-N,C,C' (CNC)] and different first-row transition metals (M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) are used to elucidate the reaction mechanism as well as the effect of the metal identity on the thermodynamics and kinetics of a methane activation reaction...
September 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28937741/influence-of-carbon-nanotube-characteristics-on-macroscopic-fiber-properties
#7
Dmitri E Tsentalovich, Robert James Headrick, Francesca Mirri, Junli Hao, Natnael Behabtu, Colin C Young, Matteo Pasquali
We study how intrinsic parameters of CNT samples affect the properties of macroscopic CNT fibers with optimized structure. We measure CNT diameter, number of walls, aspect ratio, graphitic character, and purity (residual catalyst and non-CNT carbon) in samples from 19 suppliers; we process the highest quality CNT samples into aligned, densely packed fibers, by using an established wet-spinning solution process. We find that fiber properties are mainly controlled by CNT aspect ratio and that sample purity is important for effective spinning...
September 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28937637/adsorption-mechanisms-of-dodecylbenzene-sulfonic-acid-by-corn-straw-and-poplar-leaf-biochars
#8
Nan Zhao, Xixiang Yang, Jing Zhang, Ling Zhu, Yizhong Lv
Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer-Emmett-Teller N₂ surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA)...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28937608/assessment-of-clicker-training-for-shelter-cats
#9
Lori Kogan, Cheryl Kolus, Regina Schoenfeld-Tacher
Clicker training has the potential to mitigate stress among shelter cats by providing environmental enrichment and human interaction. This study assessed the ability of cats housed in a shelter-like setting to learn new behaviors via clicker training in a limited amount of time. One hundred shelter cats were enrolled in the study. Their baseline ability to perform four specific behaviors touching a target, sitting, spinning, and giving a high-five was assessed, before exposing them to 15, five-min clicker training sessions, followed by a post-training assessment...
September 22, 2017: Animals: An Open Access Journal From MDPI
https://www.readbyqxmd.com/read/28937607/tip-pressure-on-semicircular-specimens-in-tapping-mode-atomic-force-microscopy-in-viscous-fluid-environments
#10
Hua-Ju Shih, Ching-Liang Dai, Po-Jen Shih
Tapping mode (TM) atomic force microscopy (AFM) in a liquid environment is widely used to measure the contours of biological specimens. The TM triggers the AFM probe approximately at the resonant frequencies and controls the tip such that it periodically touches the specimen along the scanning path. The AFM probe and its tip produce a hydrodynamic pressure on the probe itself and press the specimen. The tip to specimen size ratio is known to affect the measurement accuracy of AFM, however, few studies have focused on the hydrodynamic pressure caused by the effects of specimen size...
September 22, 2017: Sensors
https://www.readbyqxmd.com/read/28937545/non-contrast-pseudo-continuous-arterial-spin-labeling-and-accelerated-3-dimensional-radial-acquisition-intracranial-3-dimensional-magnetic-resonance-angiography-for-the-detection-and-classification-of-intracranial-arteriovenous-shunts
#11
Tilman Schubert, Zachary Clark, Carolina Sandoval-Garcia, Ryan Zea, Oliver Wieben, Huimin Wu, Patrick A Turski, Kevin M Johnson
OBJECTIVES: The aim of this study was to assess the sensitivity and specificity of pseudo-continuous arterial spin labeling (PCASL) magnetic resonance angiography (MRA) with 3-dimensional (3D) radial acquisition for the detection of intracranial arteriovenous (AV) shunts. MATERIALS AND METHODS: A total of 32 patients who underwent PCASL-MRA, clinical magnetic resonance imaging (MRI)/MRA exam, and digital subtraction angiography (DSA) were included in this retrospective analysis...
September 20, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/28936889/t2-relaxometry-mapping-in-demonstrating-layered-uterine-architecture-parameter-optimisation-and-utility-in-endometrial-carcinoma-and-adenomyosis-a-feasibility-study
#12
Adarsh Ghosh, Tulika Singh, Rashmi Bagga, Radhika Srinivasan, Veenu Singhla, Niranjan Khandelwal
OBJECTIVE: We evaluate the feasibility of t2 mapping of the uterus and demonstrate its diagnostic utility in endometrial carcinoma and adenomyosis and discuss the optimum imaging parameters as used in our institute. METHOD: Institute review board approval was obtained and multi spin echo imaging of the pelvic was done with variable time to echo in three patients, two with endometrial carcinoma and one with adenomyosis. T2 parametric maps and curves were plotted and the T2 times of the disease endometrium, superficial and deep myometrium were established...
September 22, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/28936697/reactive-oxygen-species-and-glutathione-antioxidants-in-the-testis-of-the-soil-biosentinel-podarcis-sicula-rafinesque-1810
#13
Giulia Guerriero, Gerardino D'Errico, Rossella Di Giaimo, Dea Rabbito, Oladokun Sulaiman Olanrewaju, Gaetano Ciarcia
Important toxicological achievements have been made during the last decades using reptiles. We focus our investigation on gonadal reproductive health of the soil biosentinel Podarcis sicula which is very sensitive to endocrine-disrupting chemicals. The aim of this study is to quantitatively detect, by sensitive microassays, reactive oxygen species and the glutathione antioxidants in the testis and investigate if they are differentially expressed before and after remediation of a site of the "Land of Fires" (Campania, Italy) subject to illicit dumping of unknown material...
September 22, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28936278/modulating-the-catalytic-activity-of-cerium-oxide-nanoparticles-with-the-anion-of-the-precursor-salt
#14
Swetha Barkam, Julian Ortiz, Shashank Saraf, Nicholas Eliason, Rameech Mccormack, Soumen Das, Ankur Gupta, Craig Neal, Alex Petrovici, Cameron Hanson, Michael D Sevilla, Amitava Adhikary, Sudipta Seal
In this work, we tested our hypothesis that surface chemistry and antioxidant properties of cerium nanoparticles (CNPs) are affected by presence of counterions. We first employed various precursor cerium (III) (Ce(III)) salts with different counterions (acetate, nitrate, chloride, sulfate) to synthesize CNPs following the same wet chemical methodology. Electron spin resonance (ESR) studies provided evidence for the formation of radicals from counterions (e.g., NO3•(2-) from reduction of NO3(-) in CNPs synthesized from Ce(III) nitrate)...
September 14, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
https://www.readbyqxmd.com/read/28935973/scaling-of-memories-and-crossover-in-glassy-magnets
#15
A M Samarakoon, M Takahashi, D Zhang, J Yang, N Katayama, R Sinclair, H D Zhou, S O Diallo, G Ehlers, D A Tennant, S Wakimoto, K Yamada, G-W Chern, T J Sato, S-H Lee
Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of [Formula: see text]...
September 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28935962/excitation-of-coupled-spin-orbit-dynamics-in-cobalt-oxide-by-femtosecond-laser-pulses
#16
Takuya Satoh, Ryugo Iida, Takuya Higuchi, Yasuhiro Fujii, Akitoshi Koreeda, Hiroaki Ueda, Tsutomu Shimura, Kazuo Kuroda, V I Butrim, B A Ivanov
Ultrafast control of magnets using femtosecond light pulses attracts interest regarding applications and fundamental physics of magnetism. Antiferromagnets are promising materials with magnon frequencies extending into the terahertz range. Visible or near-infrared light interacts mainly with the electronic orbital angular momentum. In many magnets, however, in particular with iron-group ions, the orbital momentum is almost quenched by the crystal field. Thus, the interaction of magnons with light is hampered, because it is only mediated by weak unquenching of the orbital momentum by spin-orbit interactions...
September 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28935961/field-cycling-nmr-with-high-resolution-detection-under-magic-angle-spinning-determination-of-field-window-for-nuclear-hyperpolarization-in-a-photosynthetic-reaction-center
#17
Daniel Gräsing, Pavlo Bielytskyi, Isaac F Céspedes-Camacho, A Alia, Thorsten Marquardsen, Frank Engelke, Jörg Matysik
Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect...
September 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28935931/asymmetric-electron-hole-decoherence-in-ion-gated-epitaxial-graphene
#18
Kil-Joon Min, Jaesung Park, Wan-Seop Kim, Dong-Hun Chae
We report on asymmetric electron-hole decoherence in epitaxial graphene gated by an ionic liquid. The observed negative magnetoresistance near zero magnetic field for different gate voltages, analyzed in the framework of weak localization, gives rise to distinct electron-hole decoherence. The hole decoherence rate increases prominently with decreasing negative gate voltage while the electron decoherence rate does not exhibit any substantial gate dependence. Quantitatively, the hole decoherence rate is as large as the electron decoherence rate by a factor of two...
September 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28935897/a-gateway-towards-non-collinear-spin-processing-using-three-atom-magnets-with-strong-substrate-coupling
#19
J Hermenau, J Ibañez-Azpiroz, Chr Hübner, A Sonntag, B Baxevanis, K T Ton, M Steinbrecher, A A Khajetoorians, M Dos Santos Dias, S Blügel, R Wiesendanger, S Lounis, J Wiebe
A cluster of a few magnetic atoms on the surface of a nonmagnetic substrate is one suitable realization of a bit for spin-based information technology. The prevalent approach to achieve magnetic stability is decoupling the cluster spin from substrate conduction electrons in order to suppress destabilizing spin-flips. However, this route entails less flexibility in tailoring the coupling between the bits needed for spin-processing. Here, we use a spin-resolved scanning tunneling microscope to write, read, and store spin information for hours in clusters of three atoms strongly coupled to a substrate featuring a cloud of non-collinearly polarized host atoms, a so-called non-collinear giant moment cluster...
September 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28935891/structural-properties-of-thin-film-ferromagnetic-topological-insulators
#20
C L Richardson, J M Devine-Stoneman, G Divitini, M E Vickers, C-Z Chang, M Amado, J S Moodera, J W A Robinson
We present a comprehensive study of the crystal structure of the thin-film, ferromagnetic topological insulator (Bi, Sb)2-x V x Te3. The dissipationless quantum anomalous Hall edge states it manifests are of particular interest for spintronics, as a natural spin filter or pure spin source, and as qubits for topological quantum computing. For ranges typically used in experiments, we investigate the effect of doping, substrate choice and film thickness on the (Bi, Sb)2Te3 unit cell using high-resolution X-ray diffractometry...
September 21, 2017: Scientific Reports
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