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Dai Long Vu, Karolína Ranglová, Jan Hájek, Pavel Hrouzek
Quantification of selenated amino-acids currently relies on methods employing inductively coupled plasma mass spectrometry (ICP-MS). Although very accurate, these methods do not allow the simultaneous determination of standard amino-acids, hampering the comparison of the content of selenated versus non-selenated species such as methionine (Met) and selenomethionine (SeMet). This paper reports two approaches for the simultaneous quantification of Met and SeMet. In the first approach, standard enzymatic hydrolysis employing Protease XIV was applied for the preparation of samples...
March 9, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Shinpei Ogawa, Masafumi Kimata
Electromagnetic wave absorbers have been investigated for many years with the aim of achieving high absorbance and tunability of both the absorption wavelength and the operation mode by geometrical control, small and thin absorber volume, and simple fabrication. There is particular interest in metal-insulator-metal-based plasmonic metamaterial absorbers (MIM-PMAs) due to their complete fulfillment of these demands. MIM-PMAs consist of top periodic micropatches, a middle dielectric layer, and a bottom reflector layer to generate strong localized surface plasmon resonance at absorption wavelengths...
March 20, 2018: Materials
Chunxue Hao, Bochong Wang, Fusheng Wen, Congpu Mu, Jianyong Xiang, Lei Li, Zhongyuan Liu
Through a facile self-assembled process, an ultralight reduced graphene oxide/black phosphorus (rGO/BP) composite aerogel was successfully fabricated. The BP nanosheets were homogeneously distributed throughout the rGO 3D framework, and the interfaces between rGO and BP possessed four kinds of interconnections, such as wrapping, wearing, bridging and weak linking. As an ultralight composite, the rGO/BP aerogel could easily stand on the stamen of a flower. Compared with pure rGO aerogel, the rGO/BP composite aerogel exhibited enhanced microwave absorption ability...
March 20, 2018: Nanotechnology
W Verhoeven, J F M van Rens, E R Kieft, P H A Mutsaers, O J Luiten
Ultrashort, low-emittance electron pulses can be created at a high repetition rate by using a TM110 deflection cavity to sweep a continuous beam across an aperture. These pulses can be used for time-resolved electron microscopy with atomic spatial and temporal resolution at relatively large average currents. In order to demonstrate this, a cavity has been inserted in a transmission electron microscope, and picosecond pulses have been created. No significant increase of either emittance or energy spread has been measured for these pulses...
March 10, 2018: Ultramicroscopy
Krishnendu Kundu, Akiva Feintuch, Shimon Vega
Recently it has been shown that experimental ELDOR spectra of amorphous glasses containing free radicals with inhomogeneously broadened EPR spectra can be analyzed using a set of coupled rate equations for the electron polarizations of frequency bins composing these spectra, named the eSD (electron spectral diffusion) model. The rate matrix defining these equations has elements depending on the microwave, the spin lattice relaxation rates and on eSD rate constants responsible for polarization exchange. In this study, we show that in addition to the static dipolar flip-flop terms in the Hamiltonian a zero-quantum electron cross-relaxation mechanism can be responsible for the polarization exchange process in our samples...
March 19, 2018: Journal of Physical Chemistry Letters
Weiwei Cao, Xiaoyan Yang, Fengqi Lu, Wenfeng Zhu, Laijun Liu, Xiaojun Kuang, Mathieu Allix
Isovalent substitution of Zr4+ for smaller Ti4+ was performed in the 8-layer twinned hexagonal perovskite (referred to as 8H) tantalate Ba8 Ti3 Ta4 O24 , which stabilizes a 10-layer twinned hexagonal perovskite (referred to as 10H). The formation of the 10H phase occurs at low substitution concentration ( x = 0.1) in Ba8 Zrx Ti3- x Ta4 O24 at 1300 °C and reverts back to the 8H phase upon heating at elevated temperatures. Such a 10H-to-8H phase transformation is suppressed at higher Zr-substitution contents ( x > 0...
March 19, 2018: Inorganic Chemistry
Sanna Rauhamäki, Pekka A Postila, Sanna Niinivehmas, Sami Kortet, Emmi Schildt, Mira Pasanen, Elangovan Manivannan, Mira Ahinko, Pasi Koskimies, Niina Nyberg, Pasi Huuskonen, Elina Multamäki, Markku Pasanen, Risto O Juvonen, Hannu Raunio, Juhani Huuskonen, Olli T Pentikäinen
Monoamine oxidase B (MAO-B) catalyzes deamination of monoamines such as neurotransmitters dopamine and norepinephrine. Accordingly, small-molecule MAO-B inhibitors potentially alleviate the symptoms of dopamine-linked neuropathologies such as depression or Parkinson's disease. Coumarin with a functionalized 3-phenyl ring system is a promising scaffold for building potent MAO-B inhibitors. Here, a vast set of 3-phenylcoumarin derivatives was designed using virtual combinatorial chemistry or rationally de novo and synthesized using microwave chemistry...
2018: Frontiers in Chemistry
Juliana S Novais, Caroline S Moreira, Ana Carolina J A Silva, Raquel S Loureiro, Agnes Marie Sá Figueiredo, Vitor F Ferreira, Helena C Castro, David R da Rocha
The aims of this study were the planning, synthesis and in vitro evaluation of 2-hydroxy-3-phenylsulfanylmethyl-[1,4]-naphthoquinones against Gram-negative and Gram-positive strains, searching for potential lead compounds against bacterial biofilm formation. A series of 12 new analogs of 2-hydroxy-3-phenylsulfanylmethyl-[1,4]-naphthoquinones were synthesized by adding a thiol and different substituents to a ο-quinone methide using microwave irradiation. The compounds were tested against Gram-positive (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S...
March 14, 2018: Microbial Pathogenesis
Chan Wang, Tantan Hu, Zhuoqi Wen, Jingdan Zhou, Xioajie Wang, Qian Wu, Chuanxi Wang
Nitrogen doping can effectly adjust the compositions and structures of carbon dots and hence enhance their fluorescence. In this work, we report a fast and low-cost route for synthesis of nitrogen-doped carbon dots (N-CDs) by microwave pyrolysis of citric acid and ammonium within 7 min. The as-prepared N-CDs contain plentiful oxygen and nitrogen functional groups, and dispaly intense fluorescence with high quantum yield of ca. 44.3% and have an average size of 1.8 nm. The obtained N-CDs exhibit highly stable against photobleaching, ionic strengths, and can be used for selective and sensitive detection of Fe(III)...
March 8, 2018: Journal of Colloid and Interface Science
Sunantha Ketnawa, Malithi Wickramathilaka, Andrea M Liceaga
Two samples of trout frame protein hydrolysates were prepared by Microwave Pretreatment followed by Conventional Enzymatic hydrolysis (MPCE) and Non-Pretreated followed by Microwave-assisted Enzymatic hydrolysis (NPME), respectively, were subjected to simulated gastrointestinal digestion. Changes on degree of hydrolysis, antioxidant activity, molecular weight, and amino acid composition between undigested and after gastrointestinal digestion of peptides were investigated. Comparing to undigested peptides, a breakdown of MPCE and NPME into smaller molecules was observed...
July 15, 2018: Food Chemistry
Jiaqiang Luo, Cheryl Taylor, Thomas Nebl, Ken Ng, Louise E Bennett
Animal and aquatic meats represent important sources of dietary protein and micro-nutrients. Although red and processed meats carry some risks for human health, sensory and nutritional advantages drive meat consumption. Therefore, it is important to understand how meat processing and cooking influence healthiness. The research aim was to investigate relationships of meat composition (proximates, amino acids and minerals) and cooking conditions (raw, 90 s microwave, 200 °C oven for 10 or 30 min) on protein digestibility, for a selection of four animal (beef, chicken, pork, kangaroo) and four aquatic meats (salmon, trout, prawn, oyster)...
July 15, 2018: Food Chemistry
Petra Ložnjak, Jette Jakobsen
Information on the retention of vitamin D in food following household cooking is scarce. So far the retention of its metabolites vitamin D3 , vitamin D2 , and 25-hydroxyvitamin D3 has shown that the type of food and the cooking method are the essential determinants, and there is no significant difference between the metabolites. We investigated the retention of vitamin D3 and vitamin D2 in sunflower oil, vitamin D3 in rainbow trout, and vitamin D2 in button mushrooms. The investigated cooking methods were boiling at different pH, steam cooking, microwave cooking, pan-frying, and oven baking...
July 15, 2018: Food Chemistry
S Lenaerts, M Van Der Borght, A Callens, L Van Campenhout
Freeze drying represents the current practice to stabilize mealworms, even though it is an energy demanding technique. Therefore, it was examined in the present study whether microwave drying could be a proper alternative. To this end, the impact of both drying techniques on the proximate composition, vitamin B12 content, fatty acid profile, oxidation status and colour parameters of mealworms was investigated. Furthermore, the influence of the application of vacuum during microwave drying was studied. The different drying technologies resulted in small differences in the proximate composition, while the vitamin B12 content was only reduced by microwave drying...
July 15, 2018: Food Chemistry
A Rehemanjiang, M Richter, U Kuhl, H-J Stöckmann
Following an idea by Joyner et al. [Europhys. Lett. 107, 50004 (2014)EULEEJ0295-507510.1209/0295-5075/107/50004], a microwave graph with antiunitary symmetry T obeying T^{2}=-1 has been realized, thus mimicking a spin-1/2 system. The Kramers doublets expected for such systems have been clearly identified and could be lifted by a perturbation which breaks the antiunitary symmetry. The observed spectral level-spacing distribution of the Kramers doublets agreed with the predictions from the Gaussian symplectic ensemble (GSE), expected for chaotic systems with such a symmetry...
February 2018: Physical Review. E
T R Hartke, Y-Y Liu, M J Gullans, J R Petta
Quantum confinement leads to the formation of discrete electronic states in quantum dots. Here we probe electron-phonon interactions in a suspended InAs nanowire double quantum dot (DQD) that is electric-dipole coupled to a microwave cavity. We apply a finite bias across the wire to drive a steady state population in the DQD excited state, enabling a direct measurement of the electron-phonon coupling strength at the DQD transition energy. The amplitude and phase response of the cavity field exhibit oscillations that are periodic in the DQD energy level detuning due to the phonon modes of the nanowire...
March 2, 2018: Physical Review Letters
Jingshan Han, Thibault Vogt, Christian Gross, Dieter Jaksch, Martin Kiffner, Wenhui Li
We present an experimental demonstration of converting a microwave field to an optical field via frequency mixing in a cloud of cold ^{87}Rb atoms, where the microwave field strongly couples to an electric dipole transition between Rydberg states. We show that the conversion allows the phase information of the microwave field to be coherently transferred to the optical field. With the current energy level scheme and experimental geometry, we achieve a photon-conversion efficiency of ∼0.3% at low microwave intensities and a broad conversion bandwidth of more than 4 MHz...
March 2, 2018: Physical Review Letters
Davide Bartesaghi, Adam H Slavney, María C Gélvez-Rueda, Bridget A Connor, Ferdinand C Grozema, Hemamala I Karunadasa, Tom J Savenije
Double perovskites, comprising two different cations, are potential nontoxic alternatives to lead halide perovskites. Here, we characterized thin films and crystals of Cs2 AgBiBr6 by time-resolved microwave conductance (TRMC), which probes formation and decay of mobile charges upon pulsed irradiation. Optical excitation of films results in the formation of charges with a yield times mobility product, φΣμ > 1 cm2 /Vs. On excitation of millimeter-sized crystals, the TRMC signals show, apart from a fast decay, a long-lived tail...
March 8, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Xiaolong Liu, Yuan Yu, Haitao Tang, Lu Xu, Jianji Dong, Xinliang Zhang
We propose and demonstrate a silicon-on-insulator (SOI)-based widely tunable microwave photonic filter (MPF), which is implemented by using an under-coupled microring resonator (MRR) assisted by two cascaded tunable Mach-Zehnder interferometers. In the experiment, the MPF achieves an ultrahigh peak rejection exceeding 60 dB, a full width at half-maximum bandwidth of 780 MHz, and a frequency tuning range of 0-40 GHz, even when the propagation loss of the MRR is 1.65 dB/cm. To the best of our knowledge, this MPF demonstrates ultrahigh peak rejection and narrow bandwidth simultaneously in SOI for the first time with MRR of such propagation loss and avoids using external electrical devices to improve the rejection...
March 15, 2018: Optics Letters
N Pinsker, M Papoulas, M Sodergren, P Harrison, N Heaton, K Menon
Introduction A bronchobiliary fistula (BBF) following liver directed therapy (resection/ablation) is a rare complication in which an abnormal communication between the biliary tract and bronchial tree is formed. This case report describes the successful management of a persistent BBF following multiple liver wedge resections and microwave ablation in a patient with a metastatic neuroendocrine tumour of the terminal ileum. Case history A 69-year-old man presented with unexplained weight loss and was subsequently diagnosed with a neuroendocrine tumour of the terminal ileum and liver metastasis...
March 15, 2018: Annals of the Royal College of Surgeons of England
Junling Long, H S Ku, Xian Wu, Xiu Gu, Russell E Lake, Mustafa Bal, Yu-Xi Liu, David P Pappas
Quantum networks will enable extraordinary capabilities for communicating and processing quantum information. These networks require a reliable means of storage, retrieval, and manipulation of quantum states at the network nodes. A node receives one or more coherent inputs and sends a conditional output to the next cascaded node in the network through a quantum channel. Here, we demonstrate this basic functionality by using the quantum interference mechanism of electromagnetically induced transparency in a transmon qubit coupled to a superconducting resonator...
February 23, 2018: Physical Review Letters
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