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Jing Lu, Lin Wu, Yufang Hu, Sui Wang, Zhiyong Guo
In this study, a novel electrochemiluminescence (ECL) biosensor for sensitive detection of femtomolar miRNA-141 was constructed on the basis of Faraday cage-type strategy via graphene oxide (GO) and hybridization chain reaction (HCR)-assisted cascade amplification. A capture probe (CP) was immobilized on Fe3 O4 @SiO2 @Au nanoparticles as capture unit, which could catch the miRNA-141, and the immobilization of the signal unit (Ru(phen)3 2+ -HCR/GO) was allowed via nucleic acid hybridization. The prepared biosensor exhibited two advantages for signal amplification: firstly, GO could lap on the electrode surface directly, extending Outer Helmholtz Plane (OHP) of the sensor due to the large surface area and good electronic transport property; secondly, HCR-assisted cascade amplification was designed by anchoring all HCR products on the GO surface, then embedding Ru(phen)3 2+ as a signal readout pathway...
March 6, 2018: Biosensors & Bioelectronics
Guiqin Wang, Yuling Zeng, Jifeng Xu, Wengui Liu
We report a new method for calibrating the current gain of 1013 Ω amplifiers in both positive and negative mode used in thermal ionisation mass spectrometry (TIMS). This method uses any isotopic standard or sample to calibrate the gain factor as long as it can produce a stable current signal. It is simpler and more flexible than that recommended by Thermo-Fisher (the manufacture of the TIMS). In these analyses, the gains of five 1013 Ω amplifiers were assessed. The precision of gain factors was better than 100 ppm (2 RSD) in a day, and the long term reproducibility was better than 300 ppm (2 RSD) within 2 - 8 months...
March 9, 2018: Journal of Mass Spectrometry: JMS
Chiara Genovese, Manfred E Schuster, Emma K Gibson, Diego Gianolio, Victor Posligua, Ricardo Grau-Crespo, Giannantonio Cibin, Peter P Wells, Debi Garai, Vladyslav Solokha, Sandra Krick Calderon, Juan J Velasco-Velez, Claudio Ampelli, Siglinda Perathoner, Georg Held, Gabriele Centi, Rosa Arrigo
The carbon-carbon coupling via electrochemical reduction of carbon dioxide represents the biggest challenge for using this route as platform for chemicals synthesis. Here we show that nanostructured iron (III) oxyhydroxide on nitrogen-doped carbon enables high Faraday efficiency (97.4%) and selectivity to acetic acid (61%) at very-low potential (-0.5 V vs silver/silver chloride). Using a combination of electron microscopy, operando X-ray spectroscopy techniques and density functional theory simulations, we correlate the activity to acetic acid at this potential to the formation of nitrogen-coordinated iron (II) sites as single atoms or polyatomic species at the interface between iron oxyhydroxide and the nitrogen-doped carbon...
March 5, 2018: Nature Communications
G Shaw, J Brisbois, L B G L Pinheiro, J Müller, S Blanco Alvarez, T Devillers, N M Dempsey, J E Scheerder, J Van de Vondel, S Melinte, P Vanderbemden, M Motta, W A Ortiz, K Hasselbach, R B G Kramer, A V Silhanek
We present a detailed quantitative magneto-optical imaging study of several superconductor/ferromagnet hybrid structures, including Nb deposited on top of thermomagnetically patterned NdFeB and permalloy/niobium with erasable and tailored magnetic landscapes imprinted in the permalloy layer. The magneto-optical imaging data are complemented with and compared to scanning Hall probe microscopy measurements. Comprehensive protocols have been developed for calibrating, testing, and converting Faraday rotation data to magnetic field maps...
February 2018: Review of Scientific Instruments
Daniel P Engelhart, James Patton, Elena Plis, Russell Cooper, Ryan Hoffmann, Dale Ferguson, Robert V Hilmer, John McGarity, Ernest Holeman
The Mumbo space environment simulation chamber discussed here comprises a set of tools to calibrate a variety of low flux, low energy electron and ion detectors used in satellite-mounted particle sensors. The chamber features electron and ion beam sources, a Lyman-alpha ultraviolet lamp, a gimbal table sensor mounting system, cryogenic sample mount and chamber shroud, and beam characterization hardware and software. The design of the electron and ion sources presented here offers a number of unique capabilities for space weather sensor calibration...
February 2018: Review of Scientific Instruments
Weixiong Zhao, Bo Fang, Xiaoxiao Lin, Yan-Bo Gai, Wei-Jun Zhang, Wenge Chen, Zhiyou Chen, Haifeng Zhang, Weidong Chen
Atmospheric simulation chambers play vital roles in validation of chemical mechanisms and act as a bridge between field measurements and modeling. Chambers operating at atmospheric levels of OH radicals (10^6-10^7 molecule/cm3) can significantly enhance the possibility for investigating the discrepancies between the observation and model predications. However, few chambers can directly detect chamber OH radical at ambient levels. In this paper, we report on the first combination of a superconducting magnet with mid-infrared Faraday rotation spectroscopy (FRS) for real time in-situ measurement of OH concentration in an atmospheric simulation chamber...
February 28, 2018: Analytical Chemistry
Jiaqi Zhou, Weiwei Pan, Xijia Gu, Lei Zhang, Yan Feng
A long-term stable picosecond dissipative soliton (DS) is achieved for the first time using nonlinear polarization evolution. The environmental stabilization is performed by a Faraday mirror, which can cancel environmentally induced changes in the birefringence of the fiber. The laser cavity with all-polarization-maintaining fiber components generates DS pulses with 2.9 nJ single pulse energy and 5.9 ps pulse width. The output power test over 2 hours shows the excellent mode-locking stability of this design...
February 19, 2018: Optics Express
Marie Teresa Nawka, Jan Sedlacik, Andreas Frölich, Maxim Bester, Jens Fiehler, Jan-Hendrik Buhk
OBJECTIVE: To evaluate multiparametric MRI including non-contrast and contrast-enhanced morphological and angiographic techniques for intracranial aneurysms treated with the single-layer Woven EndoBridge (WEB) embolization system applying simultaneous digital subtraction angiography (DSA) as the reference of standard. MATERIALS AND METHODS: We retrospectively identified all patients with incidental and acute ruptured intracranial aneurysms treated with a WEB device (WEB SL and WEB SLS) between March 2014 and June 2016 in our neurovascular center with early (within 7 days) postinterventional multiparametric MRI as well as mid-term (5-8 months) follow-up MRI and DSA available...
February 10, 2018: Journal of Neurointerventional Surgery
Ricardo Jiménez-Martínez, Jan Kołodyński, Charikleia Troullinou, Vito Giovanni Lucivero, Jia Kong, Morgan W Mitchell
We study causal waveform estimation (tracking) of time-varying signals in a paradigmatic atomic sensor, an alkali vapor monitored by Faraday rotation probing. We use Kalman filtering, which optimally tracks known linear Gaussian stochastic processes, to estimate stochastic input signals that we generate by optical pumping. Comparing the known input to the estimates, we confirm the accuracy of the atomic statistical model and the reliability of the Kalman filter, allowing recovery of waveform details far briefer than the sensor's intrinsic time resolution...
January 26, 2018: Physical Review Letters
Krystian Sycz, Adam M Wojciechowski, Wojciech Gawlik
We report on the creation, observation and optimization of superposition states of cold atoms. In our experiments, rubidium atoms are prepared in a magneto-optical trap and later, after switching off the trapping fields, Faraday rotation of a weak probe beam is used to characterize atomic states prepared by application of appropriate light pulses and external magnetic fields. We discuss the signatures of polarization and alignment of atomic spin states and identify main factors responsible for deterioration of the atomic number and their coherence and present means for their optimization, like relaxation in the dark with the strobed probing...
February 12, 2018: Scientific Reports
B A Smit, E Van Zyl, J J Joubert, W Meyer, S Prévéral, C T Lefèvre, S N Venter
Magnetotactic bacteria (MTB) have the unique ability to produce magnetic particles surrounded by a biomembrane to form the magnetosome organelle. Therefore, MTB have novel physical and magnetic properties and have consequently been used in several biotechnological applications. The magnetic properties of these microorganisms and their magnetosomes have, however, never been used for the generation of electricity as described in this letter. Comparisons were made between, firstly, the electricity generated from purified magnetosomes, MTB culture (bacterial cells with magnetosomes) and sterile, liquid growth medium (control)...
February 12, 2018: Letters in Applied Microbiology
M Lübbesmeyer, D Leifert, H Schäfer, A Studer
The electron-catalyzed formation of phenanthridines starting from isonitriles initiated by an electrochemical reduction of the Togni reagent is presented. The required number of faradays per mole of starting material and the respective yields clearly show the catalytic character of the electron in this reaction. The mechanism is supported by cyclic voltammetry experiments.
February 12, 2018: Chemical Communications: Chem Comm
Marceli Koralewski, Lucia Balejčíková, Zuzana Mitroova, Mikołaj Pochylski, Mikołaj Baranowski, Peter Kopcansky
The ferritin is a protein, which serves as a storage and transportation capsule for iron inside living organisms. Continuous charging protein with iron and releasing it from the ferritin is necessary to assure proper management of this important ions within organism. From other side synthetic ferritin have great potential for biomedical and technological applications. In this work the behavior of ferritin during the processes of iron loading and releasing was examined using multiplicity of experimental technique...
February 8, 2018: ACS Applied Materials & Interfaces
Lin Chen, Xiang Xu, Haifeng Zeng, Kannie W Y Chan, Nirbhay Yadav, Shuhui Cai, Kathryn J Schunke, Nauder Faraday, Peter C M van Zijl, Jiadi Xu
PURPOSE: To develop a method that can separate and quantify the fast (>1 kHz) and slow exchange transfer and magnetization transfer components in Z-spectra. METHODS: Z-spectra were recorded as a function of mixing time using a train of selective pulses providing variable-delay multipulse build-up curves. Fast and slow transfer components in the Z-spectra were separated and quantified on a voxel-by-voxel basis by fitting the mixing time-dependent CEST signal using a 3-pool model...
February 5, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
A O Maksimov, T G Leighton
The subject of acoustic radiation pressure on a gas bubble is important in many applications because it controls how bubbles are moved by acoustic fields to target locations, and often how they act upon the target. Previous theoretical treatments assume a spherical bubble undergoing linear pulsations, but some (such as cleaning using Faraday waves on the bubble wall) require that the bubble be aspherical. Therefore, this paper derives ways to calculate the variation in the radiation pressure due to the non-spherical bubble oscillations...
January 2018: Journal of the Acoustical Society of America
D Nakamura, H Sawabe, S Takeyama
The maximum magnetic field obtained by the electro-magnetic flux compression technique was investigated with respect to the initial seed magnetic field. It was found that the reduction in the seed magnetic field from 3.8 T to 3.0 T led to a substantial increase in the final peak magnetic field. The optical Faraday rotation method with a minimal size probe evades disturbances from electromagnetic noise and shockwave effects to detect such final peak fields in a reduced space of an inner wall of the imploding liner...
January 2018: Review of Scientific Instruments
Z Y Zou, H Q Liu, W X Ding, J Chen, D L Brower, H Lian, S X Wang, W M Li, Y Yao, L Zeng, Y X Jie
A double-pass radially view 11 chords polarimeter-interferometer system has been operated on the experimental advanced superconducting tokamak and provides important current profile information for plasma control. Stray light originating from spurious reflections along the optical path (unwanted reflections from various optical components/mounts and transmissive optical elements such as windows, waveplates, and lens as well as the detectors) and also direct feedback from the retro-reflector used to realize the double-pass configuration can both contribute to contamination of the Faraday rotation measurement accuracy...
January 2018: Review of Scientific Instruments
G Gitgeatpong, Y Zhao, P Piyawongwatthana, Y Qiu, L W Harriger, N P Butch, T J Sato, K Matan
Inelastic neutron scattering measurements were performed to study spin dynamics in the noncentrosymmetric antiferromagnet α-Cu_{2}V_{2}O_{7}. For the first time, nonreciprocal magnons were experimentally measured in an antiferromagnet. These nonreciprocal magnons are caused by the incompatibility between anisotropic exchange and antisymmetric Dzyaloshinskii-Moriya interactions, which arise from broken symmetry, resulting in a collinear ordered state but helical spin dynamics. The nonreciprocity introduces the difference in the phase velocity of the counterrotating modes, causing the opposite spontaneous magnonic Faraday rotation of the left- and right-propagating spin waves...
July 28, 2017: Physical Review Letters
Frank A J L James
No abstract text is available yet for this article.
January 1, 2018: Public Understanding of Science
Mahdi Ahmadi, Rajesh Rajamani, Serdar Sezen
Capacitive micro-sensors such as accelerometers, gyroscopes and pressure sensors are increasingly used in the modern electronic world. However, the in vivo use of capacitive sensing for measurement of pressure or other variables inside a human body suffers from significant errors due to stray capacitance. This paper proposes a solution consisting of a transparent thin flexible Faraday cage that surrounds the sensor. By supplying the active sensing voltage simultaneously to the deformable electrode of the capacitive sensor and to the Faraday cage, the stray capacitance during in vivo measurements can be largely eliminated...
October 2017: IEEE Sensors Letters
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