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Pawel Olczyk, Katarzyna Komosinska-Vassev, Pawel Ramos, Lukasz Mencner, Krystyna Olczyk, Barbara Pilawa
The influence of heating at a temperature of 50 °C and UV-irradiation of propolis drops and spray on their free radical scavenging activity was determined. The kinetics of interactions of the propolis samples with DPPH free radicals was analyzed. Interactions of propolis drops and propolis spray with free radicals were examined by electron paramagnetic resonance spectroscopy. A spectrometer generating microwaves of 9.3 GHz frequency was used. The EPR spectra of the model DPPH free radicals were compared with the EPR spectra of DPPH in contact with the tested propolis samples...
January 13, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Bo Lv, Jiahui Fu, Bian Wu, Rujiang Li, Qingsheng Zeng, Xinhua Yin, Qun Wu, Lei Gao, Wan Chen, Zhefei Wang, Zhiming Liang, Ao Li, Ruyu Ma
Parity-time (PT) symmetric structures present the unidirectional invisibility at the spontaneous PT-symmetry breaking point. In this paper, we propose a PT-symmetric circuit consisting of a resistor and a microwave tunnel diode (TD) which represent the attenuation and amplification, respectively. Based on the scattering matrix method, the circuit can exhibit an ideal unidirectional performance at the spontaneous PT-symmetry breaking point by tuning the transmission lines between the lumped elements. Additionally, the resistance of the reactance component can alter the bandwidth of the unidirectional invisibility flexibly...
January 18, 2017: Scientific Reports
Ghulam Ali, Asad Mehmood, Heung Yong Ha, Jaehoon Kim, Kyung Yoon Chung
We report the feasibility of using reduced graphene oxide (RGO) as a cost-effective and high performance cathode material for sodium-ion batteries (SIBs). Graphene oxide is synthesized by a modified Hummers' method and reduced using a solid-state microwave irradiation method. The RGO electrode delivers an exceptionally stable discharge capacity of 240 mAh g(-1) with a stable long cycling up to 1000 cycles. A discharge capacity of 134 mAh g(-1) is obtained at a high current density of 600 mA g(-1), and the electrode recovers a capacity of 230 mAh g(-1) when the current density is reset to 15 mA g(-1) after deep cycling, thus demonstrating the excellent stability of the electrode with sodium de/intercalation...
January 18, 2017: Scientific Reports
François Robert, Sylvie Derenne, Guillaume Lombardi, Khaled Hassouni, Armelle Michau, Peter Reinhardt, Rémi Duhamel, Adriana Gonzalez, Kasia Biron
The hydrogen isotope ratio (D/H) is commonly used to reconstruct the chemical processes at the origin of water and organic compounds in the early solar system. On the one hand, the large enrichments in deuterium of the insoluble organic matter (IOM) isolated from the carbonaceous meteorites are interpreted as a heritage of the interstellar medium or resulting from ion-molecule reactions taking place in the diffuse part of the protosolar nebula. On the other hand, the molecular structure of this IOM suggests that organic radicals have played a central role in a gas-phase organosynthesis...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
Seyed Amir Hossein Banuazizi, Sohrab R Sani, Anders Eklund, Maziar M Naiini, Seyed Majid Mohseni, Sunjae Chung, Philipp Dürrenfeld, B Gunnar Malm, Johan Åkerman
Spin torque nano-oscillators (STNO) represent a unique class of nano-scale microwave signal generators and offer a combination of intriguing properties, such as nano sized footprint, ultrafast modulation rates, and highly tunable microwave frequencies from 100 MHz to close to 100 GHz. However, their low output power and relatively high threshold current still limit their applicability and must be improved. In this study, we investigate the influence of the bottom Cu electrode thickness (tCu) in nano-contact STNOs based on Co/Cu/NiFe GMR stacks and with nano-contact diameters ranging from 60 to 500 nm...
January 17, 2017: Nanoscale
Alisa Leavesley, Daphna Shimon, Ting Ann Siaw, Akiva Feintuch, Daniella Goldfarb, Shimon Vega, Ilia Kaminker, Songi Han
Here, we present an integrated experimental and theoretical study of (1)H dynamic nuclear polarization (DNP) of a frozen aqueous glass containing free radicals at 7 T, under static conditions and at temperatures ranging between 4 and 20 K. The DNP studies were performed with a home-built 200 GHz quasi-optics microwave bridge, powered by a tunable solid-state diode source. DNP using monochromatic and continuous wave (cw) irradiation applied to the electron paramagnetic resonance (EPR) spectrum of the radicals induces the transfer of polarization from the electron spins to the surrounding nuclei of the solvent and solutes in the frozen aqueous glass...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
Vladimir Tomović, Marija Jokanović, Mila Tomović, Milana Lazović, Branislav Šojić, Snežana Škaljac, Maja Ivić, Sunčica Kocić-Tanackov, Igor Tomašević, Aleksandra Martinović
Concentrations of cadmium (Cd) were determined in the samples of 144 animals around 1 and of 144 animals around 4 years old. Cd was analyzed by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), after microwave digestion. Cd concentrations were higher (p < 0.05) in kidney than in liver and higher (p < 0.05) in older animals than in young ones. In domestic Balkan goat which was raised in a free-ranged system Cd accumulation was lower (p < 0.05) than in Alpine goat raised in an intensive production system...
January 16, 2017: Food Additives & Contaminants. Part B, Surveillance
Madhumita Dalal, Ayan Mallick, Jean-Marc Greneche, Dipankar Das, Pabitra K Chakrabarti
Nanocrystalline samples of Ni0.3Zn0.4Co0.2Cu0.1Fe2O4 (NZCCF) are prepared by a simple co-precipitation method. To obtain nanoparticles of different sizes, the as prepared sample is annealed at 400, 600, 800 and 1000 °C. Nanoparticles of the sample annealed at 600 °C are encapsulated in multi-walled carbon nanotubes (MWCNT). To confirm the crystallographic phase, x-ray diffraction (XRD) patterns are analyzed by the Rietveld method and cation distribution in A- and B-sites is estimated from the analysis. Occupancy of Zn(2+) ions in A-site and that of Fe(3+) ions in B-site increase with the increase of annealing temperature (T A) and lattice parameters lie within 8...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Daniel A Gonçalves, Ana C Soncin, George L Donati, Mirian C Dos Santos
Tungsten coil atomic emission spectrometry (WCAES) is used to determine trace levels of Mn (403.1 nm) and Cr (425.5 nm) in cow placenta. All samples were collected in Ilha Solteira, SP, Brazil. The instrumental setup is based on a tungsten filament extracted from 150 W, 15 V microscope light bulbs, a solid state power supply, fused silica lens, crossed Czerny-Turner spectrograph, and a thermoelectrically cooled charge-coupled device detector. The limits of detection (LOD) and quantification (LOQ) for Cr are 2 and 8 μg L(-1), and 20 and 60 μg L(-1) for Mn, respectively...
January 16, 2017: Biological Trace Element Research
Julian Schaumann, Manuel Loor, Derya Ünal, Anja Mudring, Stefan Heimann, Ulrich Hagemann, Stephan Schulz, Franziska Maculewicz, Gabi Schierning
A systematic study on the microwave-assisted thermolysis of the single source precursor (Et2Sb)2Te (1) in different asymmetric 1-alkyl-3-methylimidazolium- and symmetric 1,3-dialkylimidazolium-based ionic liquids (ILs) reveals the distinctive role of both the anion and the cation in tuning the morphology and microstructure of the resulting Sb2Te3 nanoparticles as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS)...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Samuel Spillane, Rupali Sharma, Athanasios Zavras, Roger Mulder, C André Ohlin, Lars Goerigk, Richard A J O'Hair, Chris Ritchie
We report a new approach for the synthesis of heterohexa- and heterodecametalates via the use of non-aqueous, microwave-assisted reaction conditions. The two novel molybdovanadates have been isolated and characterized in the solid and solution states using single-crystal X-ray diffraction, FT-IR, UV/Vis, multinuclear NMR spectroscopy, and ESI-MS. The relative stabilities of the possible structural isomers were probed using dispersion-corrected DFT calculations for both polyoxometalate systems.
January 16, 2017: Angewandte Chemie
Sofia M Rudin, David W Murray, Timothy J S Whitfeld
PREMISE OF THE STUDY: Herbarium specimens may provide a record of past environmental conditions, including heavy metal pollution. To explore this potential, we compared concentrations of copper, lead, and zinc in historical and new collections from four sites in Rhode Island, USA. METHODS: We compared historical specimens (1846 to 1916) to congener specimens collected in 2015 at three former industrial sites in Providence, Rhode Island, and one nonindustrial site on Block Island...
January 2017: Applications in Plant Sciences
Tian Zhong, Jonathan M Kindem, Jake Rochman, Andrei Faraon
Ensembles of solid-state optical emitters enable broadband quantum storage and transduction of photonic qubits, with applications in high-rate quantum networks for secure communications and interconnecting future quantum computers. To transfer quantum states using ensembles, rephasing techniques are used to mitigate fast decoherence resulting from inhomogeneous broadening, but these techniques generally limit the bandwidth, efficiency and active times of the quantum interface. Here, we use a dense ensemble of neodymium rare-earth ions strongly coupled to a nanophotonic resonator to demonstrate a significant cavity protection effect at the single-photon level-a technique to suppress ensemble decoherence due to inhomogeneous broadening...
January 16, 2017: Nature Communications
M Mirzaian, P Wisse, M J Ferraz, A R A Marques, P Gaspar, S V Oussoren, K Kytidou, J D C Codée, G van der Marel, H S Overkleeft, J M Aerts
Free sphingoid bases (lysosphingolipids) of primary storage sphingolipids are increased in tissues and plasma of several sphingolipidoses. As shown earlier by us, sphingoid bases can be accurately quantified using UPLC-ESI-MS/MS, particularly in combination with identical (13)C-encoded internal standards. The feasibility of simultaneous quantitation of sphingoid bases in plasma specimens spiked with a mixture of such standards is here described. The sensitivity and linearity of detection is excellent for all examined sphingoid bases (sphingosine, sphinganine, hexosyl-sphingosine (glucosylsphingosine), hexosyl2-sphingosine (lactosylsphingosine), hexosyl3-sphingosine (globotriaosylsphingosine), phosphorylcholine-sphingosine) in the relevant concentration range and the measurements show very acceptable intra- and inter-assay variation (<10% average)...
January 12, 2017: Clinica Chimica Acta; International Journal of Clinical Chemistry
S Khamlich, T Khamliche, M S Dhlamini, M Khenfouch, B M Mothudi, M Maaza
Silver nanoparticles (AgNPs) grown on a three dimensional (3d) graphene networks (GNs) has been successfully prepared by an efficient and rapid microwave-assisted growth process to form GNs/AgNPs nanocomposite electrode materials for supercapacitor application. The 3d nature of the used GNs offers a unique architecture, which creates an efficient conduction networks and maximum utilization of space and interface, and acts as a conductive layer for the deposited AgNPs. The electrochemical performances of the fabricated electrode were evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) tests...
January 7, 2017: Journal of Colloid and Interface Science
Carmen Gianfrani, Gianfranco Mamone, Barbara la Gatta, Alessandra Camarca, Luigia Di Stasio, Francesco Maurano, Stefania Picascia, Vito Capozzi, Giuseppe Perna, Gianluca Picariello, Aldo Di Luccia
Microwave based treatment (MWT) of wet wheat kernels induced a striking reduction of gluten, up to <20 ppm as determined by R5-antibodybased ELISA, so that wheat could be labeled as gluten-free. In contrast, analysis of gluten peptides by G12 antibody-based ELISA, mass spectrometry-based proteomics and in vitro assay with T cells of celiac subjects, indicated no difference of antigenicity before and after MWT. SDS-PAGE analysis and Raman spectroscopy demonstrated that MWT simply induced conformational modifications, reducing alcohol solubility of gliadins and altering the access of R5-antibody to the gluten epitopes...
January 11, 2017: Food and Chemical Toxicology
Canan Aydaş, Semra Tepe Çam
This study aims primarily to investigate the usage of differences in microwave (MW) saturation behaviour of food samples for identification of radiation treatment. Twenty different samples (dry plant, herbal, spice etc.) which do not have radiation specific satellite ESR signal were especially selected. It is not possible to detect radiation treatment on these samples by European standard (EN 1787, 2000). MW saturation studies were performed on all samples in the range of 0.01-160mW. Our experimental results demonstrate that radiation identification can be possible for ten samples and cannot be possible for the other ten samples by performing the MW saturation studies...
December 29, 2016: Applied Radiation and Isotopes
Brian H Kolner, Lanbing Kang
A LiNbO<sub>3</sub>-loaded microwave cavity pumped with weakly AM-modulated 30 fs optical pulses was used as a platform to investigate AM-to-PM conversion in the optical rectification process. Theoretical treatment of AM-to-PM conversion (i.e., peak-induced electrical phase deviation β<sub>i</sub> due to optical power modulation with index m) suggests that the dominant mechanism is self-group-velocity modulation due to χ<sup>(3)</sup> and cascaded χ<sup>(2)</sup> processes with a value of δ=β<sub>i</sub>/m=-151  dB, linearly dependent on the optical power at intensities of 6×10<sup>10</sup>  W/m<sup>2</sup> in a 40 mm long LiNbO<sub>3</sub> crystal...
January 15, 2017: Optics Letters
Qian Liang, Huaguo Chen, Xin Zhou, Qingfang Deng, Enming Hu, Chao Zhao, Xiaojian Gong
Microwave extraction combined ultrasonic pretreatment of flavonoids from Periploca forrestii Schltr. was investigated in this study, extraction process was firstly performed in an ultrasonic cleaner, then treated by microwave irradiation. The optimum ultrasonic time of 25 min was selected by single-factor experiments. A response surface methodology (RSM) has been used to obtain a mathematical model that describes the process and analyzes the significant parameters ethanol concentration 59.92%, liquid to raw materials ratio 21...
January 12, 2017: Electrophoresis
Jeremy B Clark, Florent Lecocq, Raymond W Simmonds, José Aumentado, John D Teufel
Quantum fluctuations of the electromagnetic vacuum produce measurable physical effects such as Casimir forces and the Lamb shift. They also impose an observable limit-known as the quantum backaction limit-on the lowest temperatures that can be reached using conventional laser cooling techniques. As laser cooling experiments continue to bring massive mechanical systems to unprecedentedly low temperatures, this seemingly fundamental limit is increasingly important in the laboratory. Fortunately, vacuum fluctuations are not immutable and can be 'squeezed', reducing amplitude fluctuations at the expense of phase fluctuations...
January 11, 2017: Nature
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