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Changhao Wang, Li Xiao, Ray Luo
Continuum solvent models, particularly those based on the Poisson-Boltzmann equation (PBE), are widely used in the studies of biomolecular structures and functions. Existing PBE developments have been mainly focused on how to obtain more accurate and/or more efficient numerical potentials and energies. However to adopt the PBE models for molecular dynamics simulations, a difficulty is how to interpret dielectric boundary forces accurately and efficiently for robust dynamics simulations. This study documents the implementation and analysis of a range of standard fitting schemes, including both one-sided and two-sided methods with both first-order and second-order Taylor expansions, to calculate molecular surface electric fields to facilitate the numerical calculation of dielectric boundary forces...
March 20, 2017: Journal of Computational Chemistry
Biao Zhao, Junwei Liu, Xiaoqin Guo, Wanyu Zhao, Luyang Liang, Chao Ma, Rui Zhang
In this article, composites consisting of porous Ni cores coated with boehmite/nickel aluminum oxide nanoflakes were successfully prepared by a versatile method. The crystal constituents and shapes of the boehmite/nickel aluminum oxide nanoflakes were strongly influenced by reaction temperature, and their microwave absorption properties were investigated in terms of complex permittivity and permeability. The results reveal that the composites comprising porous Ni cores coated with boehmite/nickel aluminum oxide synthesized at 180 °C present superior absorption properties...
March 20, 2017: Physical Chemistry Chemical Physics: PCCP
Bo Lu, Khalid Lamnawar, Abderrahim Maazouz
We provide rheological and dynamic insights into the role of an in situ reactive interphase with graft copolymers in multilayered polymer systems, using a polyamide-6 (PA6)/maleic anhydride grafted poly(vinylidene fluoride) (PVDF-g-MAH) bilayer as a model. Firstly, the influence of the reactive interphase on macroscopic melt flow behavior was studied. The in situ generated interphase from coupling reactions in bilayers significantly contributed to overall viscoelastic responses in both linear and nonlinear regimes...
March 20, 2017: Soft Matter
Nikita Kostylev, Maxim Goryachev, Andrey D Bulanov, Vladimir A Gavva, Michael E Tobar
The low dielectric losses of an isotopically pure single crystal (28)Si sample were determined at a temperature of 20 mK and at powers equivalent to that of a single photon. Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order 2 × 10(6) (dielectric loss ~5 × 10(-7)) at high powers, degrading to 7 × 10(-5) (dielectric loss ~1.4 × 10(-6) at single photon energy. A very low-loss narrow line width paramagnetic spin flip transition was detected with extreme sensitivity in (28)Si, with very small concentration below 10(10) cm(-3) (less than 10 parts per trillion) and g-factor of 1...
March 20, 2017: Scientific Reports
Shang Sun, Zhenxing Zhou, Chen Zhang, Yisheng Gao, Zonghui Duan, Shumin Xiao, Qinghai Song
Recently, color generation in resonant nanostructures have been intensively studied. Despite of their exciting progresses, the structural colors are usually generated by the plasmonic resonances of metallic nanoparticles. Due to the inherent plasmon damping, such plasmonic nanostructures are usually hard to create very distinct color impressions. Here we utilize the concept of metasurfaces to produce all-dielectric, low-loss, and high resolution structural colors. We have fabricated TiO2 metasurfaces with electron-beam lithography and a very simple lift-off process...
March 19, 2017: ACS Nano
Qingteng Zhang, Eric M Dufresne, Pice Chen, Joonkyu Park, Margaret P Cosgriff, Mohammed Yusuf, Yongqi Dong, Dillon D Fong, Hua Zhou, Zhonghou Cai, Ross J Harder, Sara J Callori, Matthew Dawber, Paul G Evans, Alec R Sandy
Ferroelectric-dielectric superlattices consisting of alternating layers of ferroelectric PbTiO_{3} and dielectric SrTiO_{3} exhibit a disordered striped nanodomain pattern, with characteristic length scales of 6 nm for the domain periodicity and 30 nm for the in-plane coherence of the domain pattern. Spatial disorder in the domain pattern gives rise to coherent hard x-ray scattering patterns exhibiting intensity speckles. We show here using variable-temperature Bragg-geometry x-ray photon correlation spectroscopy that x-ray scattering patterns from the disordered domains exhibit a continuous temporal decorrelation due to spontaneous domain fluctuations...
March 3, 2017: Physical Review Letters
Allen Caldwell, Gia Dvali, Béla Majorovits, Alexander Millar, Georg Raffelt, Javier Redondo, Olaf Reimann, Frank Simon, Frank Steffen
We propose a new strategy to search for dark matter axions in the mass range of 40-400 μeV by introducing dielectric haloscopes, which consist of dielectric disks placed in a magnetic field. The changing dielectric media cause discontinuities in the axion-induced electric field, leading to the generation of propagating electromagnetic waves to satisfy the continuity requirements at the interfaces. Large-area disks with adjustable distances boost the microwave signal (10-100 GHz) to an observable level and allow one to scan over a broad axion mass range...
March 3, 2017: Physical Review Letters
Hari Mohan Rai, Preetam Singh, Shailendra K Saxena, Vikash Mishra, M Kamal Warshi, Rajesh Kumar, Parasmani Rajput, Archna Sagdeo, Indrani Choudhuri, Biswarup Pathak, Pankaj R Sagdeo
We report an observation of room-temperature magneto-dielectric (RTMD) effect in LaGa0.7Fe0.3O3+γ compound. The contribution of intrinsic/resistive sources in the presently observed RTMD effect was analyzed by measuring direct-current (dc) magnetoresistance (MR) in four-probe geometry and frequency-dependent MR via impedance spectroscopy (MRIS). Present MRIS analysis reveals that at frequencies corresponding to grain contribution (≥1 × 10(6) Hz for present sample), the observed MD phenomenon is MR-free/intrinsic, whereas at lower probing frequencies (<1 × 10(6) Hz), the observed MD coupling appears to be MR-dominated possibly due to oxygen excess, that is, due to coexistence of Fe(3+) and Fe(4+)...
March 17, 2017: Inorganic Chemistry
Hongmiao Tian, Jinyou Shao, Xiaoliang Chen, Wei Jiang, Li Wang, Yucheng Ding
Electrically induced structure formation (EISF), as a physical approach to fabricate micro/nano-structures, has attracted much attention because of the simple process, low cost, high efficiency and wide applications on electronics, microfluidics, and so forth. Hitherto, the influence of some process parameters, such as voltage, air gap, film thickness, polymer properties, on the polymeric behavior and the structure formation has been explored, neglecting the effects of the template features, which affect the polymer deformation...
March 17, 2017: Electrophoresis
Lijun Liu, Issei Nakamura
We illustrate the effects of chain connectivity on the solvation energy of ions immersed in polymer liquids by developing a new coarse-grained molecular dynamics simulation. Our theory accounts for the dielectric response of the polymers through the connection of dipolar, monomeric units with nonlinear springs. In stark contrast to the standard Born solvation energy of ions, our results depend substantially on the chain length of the polymers. We also demonstrate the marked difference in the solvation energies of the ions immersed in non-polymeric particle mixtures, single-component polymers, polymer blends, and block copolymers...
March 17, 2017: Journal of Physical Chemistry. B
Yaşar Özlem Alifakı, Özge Şakıyan
The aim of this study was to correlate dielectric properties with quality parameters, and to optimize cake formulation and baking conditions by response surface methodology. Weight loss, color, specific volume, hardness and porosity were evaluated. The samples with different DATEM (0.4, 0.8 and 1.2%) and chickpea flour concentrations (30, 40 and 50%) were baked in microwave oven at different power (300, 350, 400 W) and baking times (2.50, 3.0, 3.50 min). It was found that microwave power showed significant effect on color, while baking time showed effect on weight loss, porosity, hardness, specific volume and dielectric properties...
March 2017: Journal of Food Science and Technology
Kyeong Tae Kang, Haeyong Kang, Jeongmin Park, Dongseok Suh, Woo Seok Choi
Quantum Hall conductance in monolayer graphene on an epitaxial SrTiO3 (STO) thin film is studied to understand the role of oxygen vacancies in determining the dielectric properties of STO. As the gate-voltage sweep range is gradually increased in the device, systematic generation and annihilation of oxygen vacancies, evidenced from the hysteretic conductance behavior in the graphene, are observed. Furthermore, based on the experimentally observed linear scaling relation between the effective capacitance and the voltage sweep range, a simple model is constructed to manifest the relationship among the dielectric properties of STO with oxygen vacancies...
March 16, 2017: Advanced Materials
C M Daikuzono, C Delaney, H Tesfay, L Florea, O N Oliveira, A Morrin, D Diamond
Herein we present a novel sensor for the detection of monosaccharides (e.g. glucose, fructose) in solution, using electrical impedance spectroscopy. The sensor is based on carbon interdigitated electrodes, printed on paper using screen printing. The surface of the electrodes was modified with a thin layer of hydrogel containing acrylamide copolymerised with 20 mol% 3-(Acrylamido)phenylboronic acid (PBA). It was observed that the hydrogel layers containing 20 mol% PBA swell considerably in the presence of glucose and fructose...
March 16, 2017: Analyst
Guangqin Gu, Changbao Han, Jingjing Tian, Cunxin Lu, Chuan He, Tao Jiang, Zhou Li, Zhong Lin Wang
As a green and eco-friendly technology, triboelectric nanogenerator (TENG) can harvest energy from human motion to generate electricity, so TENGs have been widely applied in wearable electronic devices to replace the traditional batteries. However, the surface of these TENGs is easy to be contaminated and breed bacteria, which is a threat to human health. Here, we report an antibacterial composite film-based triboelectric nanogenerator (ACF-TENG) that uses Ag exchanged zeolite (Ag-zeolite) and polypropylene (PP) composite film as the triboelectric layer...
March 16, 2017: ACS Applied Materials & Interfaces
Cheng Peng, Y Sungtaek Ju
Portable microfluidic devices are promising for point-of-care (POC) diagnosis and bio- and environmental surveillance in resource-constrained or non-laboratory environments. Lateral-flow devices, some built off paper or strings, have been widely developed but the fixed layouts of their underlying wicking/microchannel structures limit their flexibility and present challenges in implementing multistep reactions. Digital microfluidics can circumvent these difficulties by addressing discrete droplets individually...
2017: Methods in Molecular Biology
Hadar Ben-Yoav, Peter H Dykstra, William E Bentley, Reza Ghodssi
A microfluidic electrochemical lab-on-a-chip (LOC) device for DNA hybridization detection has been developed. The device comprises a 3 × 3 array of microelectrodes integrated with a dual layer microfluidic valved manipulation system that provides controlled and automated capabilities for high throughput analysis of microliter volume samples. The surface of the microelectrodes is functionalized with single-stranded DNA (ssDNA) probes which enable specific detection of complementary ssDNA targets. These targets are detected by a capacitive technique which measures dielectric variation at the microelectrode-electrolyte interface due to DNA hybridization events...
2017: Methods in Molecular Biology
S P Bierwirth, P Münzner, T A Knapp, C Gainaru, R Böhmer
Highly unusual linear-response spectra involving contributions from hydrogen-bonded supramolecular processes and from structural relaxations are found in 4-methyl-3-heptanol mixed with 2-ethyl-1-hexylbromide. Although the mean time scales of the underlying relaxations are separated by more than 3 decades, the overall spectra cannot be decomposed into a sum of these processes. This finding challenges the ubiquitous practice of disentangling susceptibility spectra of Debye liquids by adding suitable subspectra...
March 14, 2017: Journal of Chemical Physics
Keiichiro Shiraga, Aya Adachi, Masahito Nakamura, Takuro Tajima, Katsuhiro Ajito, Yuichi Ogawa
Modification of the water hydrogen bond network imposed by disaccharides is known to serve as a bioprotective agent in living organisms, though its comprehensive understanding is still yet to be reached. In this study, aiming to characterize the dynamical slowing down and destructuring effect of disaccharides, we performed broadband dielectric spectroscopy, ranging from 0.5 GHz to 12 THz, of sucrose and trehalose aqueous solutions. The destructuring effect was examined in two ways (the hydrogen bond fragmentation and disordering) and our result showed that both sucrose and trehalose exhibit an obvious destructuring effect with a similar strength, by fragmenting hydrogen bonds and distorting the tetrahedral-like structure of water...
March 14, 2017: Journal of Chemical Physics
Patrick Figliozzi, Nishant Sule, Zijie Yan, Ying Bao, Stanislav Burov, Stephen K Gray, Stuart A Rice, Suriyanarayanan Vaikuntanathan, Norbert F Scherer
To date investigations of the dynamics of driven colloidal systems have focused on hydrodynamic interactions and often employ optical (laser) tweezers for manipulation. However, the optical fields that provide confinement and drive also result in electrodynamic interactions that are generally neglected. We address this issue with a detailed study of interparticle dynamics in an optical ring vortex trap using 150-nm diameter Ag nanoparticles. We term the resultant electrodynamically interacting nanoparticles a driven optical matter system...
February 2017: Physical Review. E
Carlos Molero, Raúl Rodríguez-Berral, Francisco Mesa, Francisco Medina
Microstructured metallic devices have been extensively studied because of their interesting properties for controlling the transmission, reflection, and absorption of electromagnetic waves. A very simple implementation is an array of infinitely long parallel metal strips printed on a dielectric substrate. In the past few years, several analytical models have been reported based on the use of equivalent circuits with distributed and lumped components to account for the electrical performance of these structures...
February 2017: Physical Review. E
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