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Vanni Lopresto, Rosanna Pinto, Laura Farina, Marta Cavagnaro
Microwave thermal ablation (MTA) therapy for cancer treatments relies on the absorption of electromagnetic energy at microwave frequencies to induce a very high and localized temperature increase, which causes an irreversible thermal damage in the target zone. Treatment planning in MTA is based on experimental observations of ablation zones in ex vivo tissue, while predicting the treatment outcomes could be greatly improved by reliable numerical models. In this work, a fully dynamical simulation model is exploited to look at effects of temperature-dependent variations in the dielectric and thermal properties of the targeted tissue on the prediction of the temperature increase and the extension of the thermally coagulated zone...
June 21, 2017: Medical Engineering & Physics
Tan Shi, Roger C Walker, Igor Jovanovic, Joshua A Robinson
The remarkable electronic properties of layered semiconducting transition metal dichalcogenides (TMDs) make them promising candidates for next-generation ultrathin, low-power, high-speed electronics. It has been suggested that electronics based upon ultra-thin TMDs may be appropriate for use in high radiation environments such as space. Here, we present the effects of irradiation by protons, iron, and silver ions at MeV-level energies on a WSe2/6H-SiC vertical heterostructure studied using XPS and UV-Vis-NIR spectroscopy...
June 23, 2017: Scientific Reports
Hicham Bakkali, Eduardo Blanco, Manuel Dominguez, Jose S Garitaonandia
Discontinuous multilayer (DML) thin films, which consist of nano-granular metals (NGMs) embedded in a dielectric matrix, have attracted significant interest as engineered plasmonic metamaterials. In this study, a systematic layer-by-layer deposition of three-dimensional sub-wavelength periodic plasmonic DML structures via the radio frequency sputtering of a composite target has been reported. The overall optical response of the DML films composed of AuAl2O3 NGM homogenous layers, which are periodically sandwiched between two amorphous Al2O3 layers, are studied using reflection spectroscopic ellipsometry and transmission spectroscopy techniques...
June 23, 2017: Nanotechnology
Pankaj Kumar, Charles H Patterson
First-principles calculations of the dielectric anisotropy of the GaP/Si(001) interface are compared to the anisotropy extracted from reflectance measurements on GaP thin films on Si(001) [O. Supplie et al., Phys. Rev. B 86, 035308 (2012)PRBMDO1098-012110.1103/PhysRevB.86.035308]. Optical excitations from two states localized in several Si layers adjacent to the interface result in the observed anisotropy of the interface. The calculations show excellent agreement with experiment only for a gapped interface with a P layer in contact with Si and show that a combination of theory and experiment can reveal localized electronic states and the atomic structure at buried interfaces...
June 9, 2017: Physical Review Letters
Abdul Rahim Ferhan, Gamaliel Junren Ma, Joshua A Jackman, Tun Naw Sut, Jae Hyeon Park, Nam-Joon Cho
The integration of supported lipid membranes with surface-based nanoplasmonic arrays provides a powerful sensing approach to investigate biointerfacial phenomena at membrane interfaces. While a growing number of lipid vesicles, protein, and nucleic acid systems have been explored with nanoplasmonic sensors, there has been only very limited investigation of the interactions between solution-phase nanomaterials and supported lipid membranes. Herein, we established a surface-based localized surface plasmon resonance (LSPR) sensing platform for probing the interaction of dielectric nanoparticles with supported lipid bilayer (SLB)-coated, plasmonic nanodisk arrays...
June 23, 2017: Sensors
Jean A Boutin, Anne Bonnaud, Chantal Brasseur, Olivier Bruno, Nolwenn Lepretre, Peter Oosting, Sophie Coumailleau, Philippe Delagrange, Olivier Nosjean, Céline Legros
The search for melatonin receptor agonists and antagonists specific towards one of the receptor subtypes will extend our understanding of the role of this system in relaying circadian information to the body. A series of compounds derived from a hit compound discovered in a screening process led to powerful agonists specific for one of the isoform of the melatonin receptor namely, MT₂. The compounds are based on a poorly explored skeleton in the molecular pharmacology of melatonin. By changing the steric hindrance of one substituent (i...
June 23, 2017: International Journal of Molecular Sciences
Miao Wang, Fuyang Xu, Yu Lin, Bing Cao, Linghua Chen, Chinhua Wang, Jianfeng Wang, Ke Xu
We proposed and demonstrated an integrated high energy efficient and high linearly polarized InGaN/GaN green LED grown on (0001) oriented sapphire with combined metasurface polarizing converter and polarizer system. It is different from those conventional polarized light emissions generated with plasmonic metallic grating in which at least 50% high energy loss occurs inherently due to high reflection of the transverse electric (TE) component of an electric field. A reflecting metasurface, with a two dimensional elliptic metal cylinder array (EMCA) that functions as a half-wave plate, was integrated at the bottom of a LED such that the back-reflected TE component, that is otherwise lost by a dielectric/metal bi-layered wire grids (DMBiWG) polarizer on the top emitting surface of the LED, can be converted to desired transverse magnetic (TM) polarized emission after reflecting from the metasurface...
June 23, 2017: Nanoscale
Shinji Miwa, Motohiro Suzuki, Masahito Tsujikawa, Kensho Matsuda, Takayuki Nozaki, Kazuhito Tanaka, Takuya Tsukahara, Kohei Nawaoka, Minori Goto, Yoshinori Kotani, Tadakatsu Ohkubo, Frédéric Bonell, Eiiti Tamura, Kazuhiro Hono, Tetsuya Nakamura, Masafumi Shirai, Shinji Yuasa, Yoshishige Suzuki
Electric fields at interfaces exhibit useful phenomena, such as switching functions in transistors, through electron accumulations and/or electric dipole inductions. We find one potentially unique situation in a metal-dielectric interface in which the electric field is atomically inhomogeneous because of the strong electrostatic screening effect in metals. Such electric fields enable us to access electric quadrupoles of the electron shell. Here we show, by synchrotron X-ray absorption spectroscopy, electric field induction of magnetic dipole moments in a platinum monatomic layer placed on ferromagnetic iron...
June 23, 2017: Nature Communications
Zhongyang Wang, Kai Sun, Peitao Xie, Yao Liu, Runhua Fan
Recently, negative parameters such as negative permittivity and negative permeability are attracting extensive attention for their unique electromagnetic properties. Usually, negative permittivity is well achieved by plasma oscillation of free electrons in conductor-insulator composites or metamaterials, while some attention has been drawn to attaining the negative permittivity in ceramics to reduce the dielectric loss. In this paper, negative permittivity in barium titanate and yttrium iron garnet composites was reported which was well fitted by Lorentz model...
June 23, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
R Elilarassi, G Chandrasekaran
In the present investigation, diluted magnetic semiconductor (Zn1-xFexO) nanoparticles with different doping concentrations (x=0, 0.02, 0.04, 0.06, and 0.08) were successfully synthesized by sol-gel auto-combustion method. The crystal structure, morphology, optical, electrical and magnetic properties of the prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis using x-rays (EDAX), ultraviolet-visible spectrophotometer, fluorescence spectroscope (FS), vibrating sample magnetometer (VSM) and broad band dielectric spectrometer (BDS)...
May 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Manuel Grundmann
Label-free biosensors are increasingly employed in drug discovery. Cell-based biosensors provide valuable insights into the biological consequences of exposing cells and tissues to chemical agents and the underlying molecular mechanisms associated with these effects. Optical biosensors based on the detection of dynamic mass redistribution (DMR) and impedance biosensors using cellular dielectric spectroscopy (CDS) capture changes of the cytoskeleton of living cells in real time. Because signal transduction correlates with changes in cell morphology, DMR and CDS biosensors are exquisitely suited for recording integrated cell responses in an unbiased, yet pathway-specific manner without the use of labels that may interfere with cell function...
June 22, 2017: Current Protocols in Pharmacology
Marcia Oliveira Fenley, Alexander H Boschitsch, Robert C Harris
Many researchers compute surface maps of the electrostatic potential with the Poisson-Boltzmann (PB) equation to relate the structural information obtained from X-ray and NMR experiments to biomolecular functions. Here we demonstrate that the usual method of obtaining these surface maps of electrostatic potential, by interpolating from neighboring grid points on the solution grid generated by a PB solver, generates large errors because of the large discontinuity in the dielectric constant (and thus in the normal derivative of the electrostatic potential) at the surface...
June 22, 2017: Journal of Chemical Theory and Computation
Hyeongwon Choi, Eun Ha Choi, Kyung Sook Kim
Mechanical properties of a single cell are closely related to the fate and functions of the cell. Changes in mechanical properties may cause diseases or cell apoptosis. Selective cytotoxic effects of nonthermal atmospheric pressure micro-dielectric barrier discharge (DBD) plasma have been demonstrated on cancer cells. In this work, changes in the mechanical properties of a single cell induced by nonthermal atmospheric pressure micro-DBD plasma were investigated using atomic force microscopy (AFM). Two cervical cancer cell lines (HeLa and SiHa) and normal human fibroblast cells (HFBs) were exposed to micro-DBD plasma for various exposure times...
June 22, 2017: Microscopy Research and Technique
Daming Fan, Liyun Wang, Nana Zhang, Lei Xiong, Luelue Huang, Jianxin Zhao, Mingfu Wang, Hao Zhang
The effect of non-ionizing microwave radiation on starch is due to a gelatinization temperature range that changes starch structure and properties. However, the changes in starch upon microwave heating are observable throughout the heating process. We compared the effects on starch heating by microwaves to the effects by rapid and regular conventional heating. Our results show that microwave heating promotes the rapid rearrangement of starch molecules at low temperatures; starch showed a stable dielectric response and a high dielectric constant...
June 21, 2017: Scientific Reports
Benjamin Vial, Max Munoz Torrico, Yang Hao
We report the design, fabrication and experimental verification of an illusion device working at microwave frequencies. A two dimensional topology optimization procedure is employed to find the binary layout of a dielectric coating that, when wrapped around a metallic cylinder, mimics the scattering from a predefined, arbitrarily-shaped dielectric object. Fabrication is carried out with 3D-printing and spatially resolved near field measurements in a waveguide configuration were performed, allowing us to map the illusion effect...
June 21, 2017: Scientific Reports
Zhonglei Li, Boxue Du, Chenlei Han, Hang Xu
The role of trap characteristics in modulating charge transport properties is attracting much attentions in electrical and electronic engineering, which has an important effect on the electrical properties of dielectrics. This paper focuses on the electrical properties of Low-density Polyethylene (LDPE)/graphene nanocomposites (NCs), as well as the corresponding trap level characteristics. The dc conductivity, breakdown strength and space charge behaviors of NCs with the filler content of 0 wt%, 0.005 wt%, 0...
June 21, 2017: Scientific Reports
Hong Zhang, Jie Jiang, Na Li, Ming Li, Yingying Wang, Jing He, Hong You
A variant of dielectric-barrier discharge named surface desorption dielectric-barrier discharge ionization (SDDBDI) mass spectrometry was developed for high-efficiency ion transmission and high spatial resolution imaging. In SDDBDI, a tungsten nanotip and the inlet of the mass spectrometer are used as electrodes, and a piece of cover slip is used as a sample plate as well as an insulating dielectric barrier, which simplifies the configuration of instrument and thus the operation. Different from volume dielectric-barrier discharge (VDBD), the microdischarges are generated on the surface at SDDBDI, and therefore the plasma density is extremely high...
June 21, 2017: Analytical Chemistry
Benedikt Röska, So-Hyun Park, Yusuke Yoshimori, Kenta Kimura, Tsuyoshi Kimura
An anomalous increase in the real part of dielectric response is observed in Mn<sub>0.5</sub>Fe<sub>0.5</sub>AlPO<sub>4</sub>(OH)<sub>2</sub>H<sub>2</sub>O while cooling to ~70 K. This is addressed to field-induced proton dynamics in a short hydrogen bond of 2.480(3) Å. The absence of discontinuities in heat capacity curves above the Néel temperature (T<sub>N</sub> ≈ 7 K) excludes a paraelectric to antiferroelectric phase transition...
June 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Andrei Diaconu, Simona-Lacramioara Lupu, Ionela Rusu, Ioan-Marian Risca, Lionel Salmon, Gabor Molnár, Azzedine Bousseksou, Philippe Demont, Aurelian Rotaru
We report on the effect of hydrostatic pressure on the electrical conductivity and dielectric permittivity of the [Fe(Htrz)2(trz)](BF4) (Htrz = 1H-1,2,4, triazole) spin crossover complex. Variable temperature and pressure broadband imped-ance spectrometry revealed a piezo-resistive effect of more than one order of magnitude for pressures as low as 500 bar, associated with a large pressure-induced hysteresis of 1700 bar. The origin of the piezo-resistive effect has been attributed to the pressure induced spin-state switching in the complex and the associated P,T phase diagram was determined...
June 21, 2017: Journal of Physical Chemistry Letters
Charles B Sweeney, Blake A Lackey, Martin J Pospisil, Thomas C Achee, Victoria K Hicks, Aaron G Moran, Blake R Teipel, Mohammad A Saed, Micah J Green
Additive manufacturing through material extrusion, often termed three-dimensional (3D) printing, is a burgeoning method for manufacturing thermoplastic components. However, a key obstacle facing 3D-printed plastic parts in engineering applications is the weak weld between successive filament traces, which often leads to delamination and mechanical failure. This is the chief obstacle to the use of thermoplastic additive manufacturing. We report a novel concept for welding 3D-printed thermoplastic interfaces using intense localized heating of carbon nanotubes (CNTs) by microwave irradiation...
June 2017: Science Advances
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