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Magnetization transfer

Alessandro Agostini, Jens Niklas, Tim Schulte, Marilena Di Valentin, Marco Bortolus, Eckhard Hofmann, Wolfgang Lubitz, Donatella Carbonera
The peridinin-chlorophyll-a protein (PCP) is a water-soluble light harvesting protein of the dinoflagellate Amphidinium carterae, employing peridinin (Per) as the main carotenoid to fulfil light harvesting and photo-protective functions. Per molecules bound to the protein experience specific molecular surroundings which lead to different electronic and spectral properties. In the refolded N89 L variant PCP (N89 L-RFPCP) a significant part of the intensity on the long wavelength side of the absorption spectrum is shifted to shorter wavelengths due to a significant change in the Per-614 site energy...
May 18, 2018: Biochimica et Biophysica Acta
Markus Kinauer, Martin Diefenbach, Heiko Bamberger, Serhiy Demeshko, Edward J Reijerse, Christian Volkmann, Christian Würtele, Joris van Slageren, Bas de Bruin, Max C Holthausen, Sven Schneider
The iridium(iii/iv/v) imido redox series [Ir(N t Bu){N(CHCHP t Bu2 )2 }]0/+/2+ was synthesized and examined spectroscopically, magnetically, crystallographically and computationally. The monocationic iridium(iv) imide exhibits an electronic doublet ground state with considerable 'imidyl' character as a result of covalent Ir-N t Bu bonding. Reduction gives the neutral imide [Ir(N t Bu){N(CHCHP t Bu2 )2 }] as the first example of an iridium complex with a triplet ground state. Its reactivity with respect to nitrene transfer to selected electrophiles (CO2 ) and nucleophiles (PMe3 ), respectively, is reported...
May 14, 2018: Chemical Science
Lina A Basal, Matthew D Bailey, Jonathan Romero, Meser M Ali, Lyazat Kurenbekova, Jason Yustein, Robia G Pautler, Matthew J Allen
Magnetic resonance imaging (MRI) using redox-active, EuII -containing complexes is one of the most promising techniques for noninvasively imaging hypoxia in vivo . In this technique, positive ( T 1 -weighted) contrast enhancement persists in areas of relatively low oxidizing ability, such as hypoxic tissue. Herein, we describe a fluorinated, EuII -containing complex in which the redox-active metal is caged by intramolecular interactions. The position of the fluorine atoms enables temperature-responsive contrast enhancement in the reduced form of the contrast agent and detection of the oxidized contrast agent via MRI in vivo ...
December 1, 2017: Chemical Science
Hongmei Fang, Nuli Xie, Min Ou, Jin Huang, Wenshan Li, Qing Wang, Jianbo Liu, Xiaohai Yang, Kemin Wang
Nucleic acids, as one kind of significant biomarkers, have attracted tremendous attention and exhibited immense value in fundamental studies and clinical applications. In this work, we developed a fluorescent assay for detecting nucleic acids in complex samples based on magnetic microbead (MMB)-assisted catalyzed hairpin assembly (CHA) and donor donor-acceptor fluorescence resonance energy transfer ("DD-A" FRET) signaling mechanism. Three types of DNA hairpin probes were employed in this system, including Capture, H1 (double FAM-labelled probe as FRET donor) and H2 (TAMRA-labelled probe as FRET acceptor)...
May 21, 2018: Analytical Chemistry
Ilia Kaminker, Songi Han
Dynamic nuclear polarization (DNP) takes center stage in nuclear magnetic resonance (NMR) as a tool to amplify its signal by orders of magnitude through the transfer of polarization from electron to nuclear spins. In contrast to modern NMR and electron paramagnetic resonance (EPR) that extensively rely on pulses for spin manipulation in the time domain, the current mainstream DNP technology exclusively relies on monochromatic continuous wave (CW) irradiation. This study introduces arbitrary phase shaped pulses that constitute a train of coherent chirp pulses in the time domain at 200 GHz (7 Tesla) to dramatically enhance the saturation bandwidth and DNP performance compared to CW DNP, yielding up to 500-fold in NMR signal enhancements...
May 18, 2018: Journal of Physical Chemistry Letters
Shuzhen Lv, Kangyao Zhang, Yongyi Zeng, Dianping Tang
A new double photosystems-based 'Z-scheme' photoelectrochemical (PEC) sensing platform is designed for ultrasensitive detection of prostate-specific antigen (PSA) by coupling with three-dimensional (3D) DNA walker. Two photosystems consist of CdS quantum dots (photosystem I; PS I) and BiVO4 photoactive materials (photosystem II; PS II), whereas gold nanoparticles (AuNPs) photodeposited on high-active {010} facets of BiVO4 are used as the electron mediators to promote electron transfer from conduction band (CB) of PS II to valence band (VB) of PS I...
May 18, 2018: Analytical Chemistry
Hyunjun Kim, Sang-Jun Suh, Ho-Jun Kang, Min-Seok Lee, Yoon-Soo Lee, Jeong-Ho Lee, Dong-Gee Kang
Objective: Patients with traumatic acute subdural hematoma (ASDH) often require surgical treatment. Among patients who primarily underwent craniotomy for the removal of hematoma, some consequently developed aggressive intracranial hypertension and brain edema, and required secondary decompressive craniectomy (DC). To avoid reoperation, we investigated factors which predict the requirement of DC by comparing groups of ASDH patients who did and did not require DC after craniotomy. Methods: The 129 patients with ASDH who underwent craniotomy from September 2007 to September 2017 were reviewed...
April 2018: Korean Journal of Neurotrauma
Helge Lux, Matthias Edling, Peter Siemroth, Sigurd Schrader
In this paper, we present an innovative and ultra-fast process for the deposition of high-quality graphene on different metal foils and thin metal films. The graphene layer can be homogeneously deposited in only 30 s process time. Due to the weak adhesion to the substrate material, the monolayer graphene is easy to transfer using the established processes. For the production, we use magnetic filtered high-current arc evaporation (Φ-HCA) with a solid, graphitic carbon source. This ultra-fast growth process can pave the way towards a cost-effective graphene synthesis for the mass production e...
May 16, 2018: Materials
Nicholas J Freeman, Henrik Odéen, Dennis L Parker
PURPOSE: Evaluate a numerical inverse Green's function method of deriving specific absorption rates (SARs) from high intensity focused ultrasound (HIFU) sonications given tissue parameters (thermal conductivity, specific heat capacity, and mass density) and 3-D magnetic resonance imaging (MRI) temperature measurements. METHODS: SAR estimates were evaluated using simulations and MR temperature measurements from HIFU sonications. For simulations, a "true" SAR was calculated using the hybrid angular spectrum method for ultrasound simulations...
May 17, 2018: Medical Physics
Anastassia Karageorgis, Stephen C Lenhard, Brittany Yerby, Mikael F Forsgren, Serguei Liachenko, Edvin Johansson, Mark A Pilling, Richard A Peterson, Xi Yang, Dominic P Williams, Sharon E Ungersma, Ryan E Morgan, Kim L R Brouwer, Beat M Jucker, Paul D Hockings
Drug-induced liver injury (DILI) is a leading cause of acute liver failure and transplantation. DILI can be the result of impaired hepatobiliary transporters, with altered bile formation, flow, and subsequent cholestasis. We used gadoxetate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), combined with pharmacokinetic modelling, to measure hepatobiliary transporter function in vivo in rats. The sensitivity and robustness of the method was tested by evaluating the effect of a clinical dose of the antibiotic rifampicin in four different preclinical imaging centers...
2018: PloS One
Hongmei Liu, Xiaolong Li, Changmin Shi, Dongchao Wang, Li Chen, Yuanyuan He, Jianwei Zhao
The recently synthesized two-dimensional metal bis(dithiolene) complex (MDT), a kind of metal-organic framework with a kagome lattice structure, has been found to be a promising material for electronic devices. Here we report the surface adsorption effects of gas molecules on the electronic properties and transport behaviors of two-dimensional MDT (M = Fe, Co, Ni, Pd, and Pt) films. The first-principles results reveal that the MDT nanosheets are selectively sensitive to different adsorbed molecules, such as CO, NO, and O2 molecules...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
Ping Yin, Hua Xiong, Yi Liu, Shambhu K Sah, Chun Zeng, Jingjie Wang, Yongmei Li, Nan Hong
Objective: To investigate the application value of using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with extended Tofts linear model for relapsing-remitting multiple sclerosis (RRMS) and its correlation with expanded disability status scale (EDSS) scores and disease duration. Materials and Methods: Thirty patients with multiple sclerosis (MS) underwent conventional magnetic resonance imaging (MRI) and DCE-MRI with a 3.0 Tesla MR scanner. An extended Tofts linear model was used to quantitatively measure MR imaging biomarkers...
May 2018: Neurology India
Vlastimil Dorcak, David Novak, Martin Kabelac, Ondrej Kroutil, Lucie Bednarova, Václav Veverka, Jan Vacek
Molecular wires are functional molecules applicable in the field of transfer processes in technological and biochemical applications. Besides molecular wires with the ability to transfer electrons, research is currently focused on molecular wires with high proton affinity and proton transfer ability. Recently proposed peptidic proton wires (H-wires) are one example. Their ability to mediate the transport of protons from aqueous solutions onto the surface of a Hg electrode in a catalytic hydrogen evolution reaction (CHER) was investigated by constant-current chronopotentiometric stripping (CPS)...
May 15, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Ye Liu, Akash Kannegulla, Bo Wu, Li-Jing Cheng
Spherical fullerene (C60 ) can quench the fluorescence of a quantum dot (QD) through energy transfer and charge transfer processes, with the quenching efficiency regulated by the number of proximate C60 on each QD. With the quenching property and its small size compared with other nanoparticle-based quenchers, it is advantageous to group a QD reporter and multiple C60 -labeled oligonucleotide probes to construct a molecular beacon (MB) probe for sensitive, robust nucleic acid detection. We demonstrated a rapid, high-sensitivity DNA detection method using the nanosensors composed of QD-C60 based MBs carried by magnetic nanoparticles (MNPs)...
May 15, 2018: ACS Applied Materials & Interfaces
Anja Müller-Lutz, Alexandra Ljimani, Julia Stabinska, Moritz Zaiss, Johannes Boos, Hans-Jörg Wittsack, Christoph Schleich
PURPOSE: The study compares glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging of intervertebral discs corrected for solely B0 inhomogeneities or both B0 and B1 inhomogeneities. METHODS: Lumbar intervertebral discs of 20 volunteers were examined with T2 -weighted and gagCEST imaging. Field inhomogeneity correction was performed with B0 correction only and with correction of both B0 and B1 . GagCEST effects measured by the asymmetric magnetization transfer ratio (MTRasym ) and signal-to-noise ratio (SNR) were compared between both methods...
May 14, 2018: Magma
Sergey Korchak, Shengjun Yang, Salvatore Mamone, Stefan Glöggler
Diseases such as Alzheimer's and cancer have been linked to metabolic dysfunctions, and further understanding of metabolic pathways raises hope to develop cures for such diseases. To broaden the knowledge of metabolisms in vitro and in vivo, methods are desirable for direct probing of metabolic function. Here, we are introducing a pulsed nuclear magnetic resonance (NMR) approach to generate hyperpolarized metabolites within seconds, which act as metabolism probes. Hyperpolarization represents a magnetic resonance technique to enhance signals by over 10 000-fold...
May 2018: ChemistryOpen
Parasmani Pageni, Peng Yang, Marpe Bam, Tianyu Zhu, Yung Pin Chen, Alan W Decho, Mitzi Nagarkatti, Chuanbing Tang
Over-prescription and improper use of antibiotics has led to the emergence of bacterial resistance, posing a major threat to public health. There has been significant interest in the development of alternative therapies and agents to combat antibiotic resistance. We report the preparation of recyclable magnetic iron oxide nanoparticles grafted with charged cobaltocenium-containing metallopolymers by surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization. β-Lactam antibiotics were then conjugated with metallopolymers to enhance their vitality against both Gram-positive and Gram-negative bacteria...
May 3, 2018: Biomaterials
P A Robinson, J C Pagès, N C Gabay, T Babaie, K N Mukta
Neural field theory is used to predict and analyze the phenomenon of perceptual echo in which random input stimuli at one location are correlated with electroencephalographic responses at other locations. It is shown that this echo correlation (EC) yields an estimate of the transfer function from the stimulated point to other locations. Modal analysis then explains the observed spatiotemporal structure of visually driven EC and the dominance of the alpha frequency; two eigenmodes of similar amplitude dominate the response, leading to temporal beating and a line of low correlation that runs from the crown of the head toward the ears...
April 2018: Physical Review. E
Jeramy Lewis, Robert E Camley, Nicholas R Anderson
We study nonlinear spin motion in one-dimensional magnetic chains. We find significant differences from the classic Fermi-Pasta-Ulam (FPU) problem examining nonlinear elastic motion in a chain. We find that FPU behavior, the transfer of energy among low order eigenmodes, does not occur in magnetic systems with only exchange and external fields, but does exist if a uniaxial anisotropy is also present. The FPU behavior may be altered or turned off through the magnitude and orientation of an external magnetic field...
April 20, 2018: Physical Review Letters
Cristiano Nisoli
While particle-based ices are often considered essentially equivalent to magnet-based spin ices, the two differ essentially in frustration and energetics. We show that at equilibrium particle-based ices correspond exactly to spin ices coupled to a background field. In trivial geometries, such a field has no effect, and the two systems are indeed thermodynamically equivalent. In other cases, however, the field controls a richer phenomenology, absent in magnetic ices, and still largely unexplored: ice rule fragility, topological charge transfer, radial polarization, decimation induced disorder, and glassiness...
April 20, 2018: Physical Review Letters
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