bluuebunny/crossref_metadata_2025 huggingface dataset:
Compensator design based on inverted decoupling for non‐square processes
Authors: Luan Xiaoli , Chen Qiang , Albertos Pedro , Liu Fei
Published: January 2017

The design of decoupling controllers for multivariable systems with time delays is a complex issue, even more for non‐square plants, and some approximations are usually required. In this study, based on the inverted decoupling structure, a model‐based designed centralised controller is decomposed into two controllers: one is in the direct path and the other is in a feedback loop. Owing to the non‐square nature of the process, the expression of the controller in the direct path might be very complicated, mainly for large‐size systems. The main contribution of this study is the introduction of a new diagonal pre‐compensator which to simplify the controller structure. The different possible configurations of the controller structure are analysed to satisfy the physical realisability of the compensators taking into account the possible existence of time delays and non‐minimum phase behaviour. The control goal is to achieve a decoupled dynamic behaviour characterised by the bandwidth of each loop. Comparisons with existing works through several simulation examples demonstrate the effectiveness and significant performance improvement of the proposed methodology. The need of additional manipulated variables is illustrated.
Stability analysis of fractional differential time‐delay equations
Authors: Thanh Nguyen T. , Trinh Hieu , Phat Vu N.
Published: January 2017

This study provides a novel analytical approach to studying the solutions and stability of fractional differential delay equations without using Lyapunov function method. By applying the properties of Caputo fractional derivatives, the Laplace transform and the Mittag–Leffler function, the authors first provide an explicit formula and solution bounds for the solutions of linear fractional differential delay equations. Then, they prove new sufficient conditions for exponential boundedness, asymptotic stability and finite‐time stability of such equations. The results are illustrated by numerical examples.
Fast and secure detection technique for loss of field occurrence in synchronous generators
Authors: Hasani Abbas , Haghjoo Farhad
Published: January 2017

Loss of field (LOF) phenomenon in synchronous generators may cause serious damages and voltage drop in the power system, which can result in a blackout. Conventional methods, which detect LOF on the basis of the measured impedance from terminal viewpoint, are slow and may exhibit mal‐operation in the face of other phenomena, e.g. stable power swing (SPS). In this paper, a novel technique is proposed to detect LOF in synchronous generators on the basis of some electrical quantities variations including voltage of terminal (V), current (I), active power (P), reactive power (Q) and power angle (δ). To evaluate the performance of the proposed algorithm, some cases are simulated under various operation conditions. Obtained results show that this algorithm on the basis of V, Q and δ not only can be considered as a fast LOF detector in comparison with the conventional impedance‐based schemes, but also it is a robust and secure technique in the face of SPS and other power system disturbances. The proposed algorithm is tested by using an experimental setup including the laboratory synchronous generators, too. The obtained results show that the proposed technique can exhibit suitable performance in the actual conditions.
Use of superconducting fault current limiters for mitigation of distributed generation influences in radial distribution network fuse–recloser protection systems
Authors: Wheeler Keaton , Elsamahy Mohamed , Faried Sherif
Published: January 2017

In this study, extensive dynamic simulation studies are carried out to explore the impact of synchronous machine (SM)‐based distributed generation (DG) integration on existing radial fuse–recloser protection infrastructure. Furthermore, dynamic simulation studies are also conducted to highlight the use of superconducting fault current limiters (SFCLs) to mitigate such an impact. These studies have included the effects of SM‐based DG sources on fuse–recloser coordination and recloser sensitivity adequacy. In addition, a comparison between the performances of two different SFCL types has been also offered. The dynamic results of these investigations have shown that the presence of SFCLs has prevented any excessive fault current contribution from SM‐based DG sources, as a result, it has restored the fuse–recloser coordination and recloser sensitivity adequacy. Within the frame of reference of the study is the dynamic simulations of a test benchmark that have been conducted using the PSCAD/EMTDC software.
Pollution accumulation characteristics of insulators under natural rainfall
Authors: Jiang Zidan , Jiang Xingliang , Guo Yujun , Hu Yuyao , Meng Zhigao
Published: January 2017

Under natural environment, the washing effect of rainfall has great influence on the cleaning of outdoor insulators. To study the law of natural contamination on the insulator surface in the rainy weather. The natural contamination experimental study has been carried out for four 500 kV transmission lines in hundreds of sites and stations in Hunan Province for five years. The equivalent salt deposit density (ESDD) and non‐soluble deposit density (NSDD) were measured monthly, and the meteorological data were statistically analysed. The results show that the residual ESDD and NSDD on the surface of insulators were affected by the rainfall intensity, duration and flushing angle. Meanwhile, based on the measured data of ESDD and NSDD, a cleaning model of insulators was established. The effects of splash on the bottom surface of insulators were studied by using the raindrop kinetic energy and Gaussian probability statistical distribution.
Optimal capacity planning of MG with multi‐energy coordinated scheduling under uncertainties considered
Authors: Bao Zhejing , Zhou Qin , Wu Lei , Yang Zhihui , Zhang Jianhua
Published: January 2017

Multi‐objective optimisation of capacity planning for a grid‐connected Microgrid (MG) with multi‐energy demands is developed in this study. The optimal multi‐energy coordinated scheduling, in which uncertainties of renewable energy generation and electricity demand are described by uncertainty intervals, is considered within the capacity planning model. To solve the capacity planning problem while considering the optimal scheduling with uncertainties, a two‐level optimisation approach is proposed by integrating interval mixed integer linear programming for scheduling into the multi‐objective particle swarm optimisation for capacity planning. The multi‐objective addresses the economic issue by minimising the worst‐case optimal annual costs of device investments, operation and maintenance, and pollutant emission treatment, as well as the reliability concern by minimising the worst‐case optimal annual costs of energy outage. Several MG cases studies are shown to demonstrate the proposed method.
Optimal monitoring of voltage sags through simultaneous analysis of short‐circuits in distribution systems
Authors: Kempner Thais R. , Oleskovicz Mário , Gomes Douglas P.S.
Published: January 2017

This study aims to ensure the observability of voltage sags in the entire distribution system (DS) for any short‐circuit manifested by the optimal allocation of monitors focusing on power quality. After determining a voltage sag matrix for each type of short‐circuit (balanced or unbalanced), a resulting binary matrix is determined which simultaneously observes the voltage sags for all types of faults. Later, a proposal is made to reduce this matrix to decrease the computational effort in large DS. Furthermore, the vulnerability of each node is analysed to establish the monitors’ installation priority. The IEEE 13‐nodes distribution test system is used to describe each step of the methodology in detail. Moreover, the IEEE 123‐nodes distribution test system is used to validate the results observed so far.
Combination of adaptive vector median filter and weighted mean filter for removal of high‐density impulse noise from colour images
Authors: Roy Amarjit , Singha Joyeeta , Manam Lalit , Laskar Rabul Hussain
Published: January 2017

In this study, a combination of adaptive vector median filter (VMF) and weighted mean filter is proposed for removal of high‐density impulse noise from colour images. In the proposed filtering scheme, the noisy and non‐noisy pixels are classified based on the non‐causal linear prediction error. For a noisy pixel, the adaptive VMF is processed over the pixel where the window size is adapted based on the availability of good pixels. Whereas, a non‐noisy pixel is substituted with the weighted mean of the good pixels of the processing window. The experiments have been carried out on a large database for different classes of images, and the performance is measured in terms of peak signal‐to‐noise ratio, mean squared error, structural similarity and feature similarity index. It is observed from the experiments that the proposed filter outperforms (∼1.5 to 6 dB improvement) some of the existing noise removal techniques not only at low density impulse noise but also at high‐density impulse noise.
Concept and numerical simulations of a widely tunable GaAs‐based sampled‐grating diode laser emitting at 976 nm
Authors: Tawfieq Mahmoud , Wenzel Hans , Brox Olaf , Della Casa Pietro , Sumpf Bernd , Tränkle Günther
Published: January 2017

Tunable diode lasers are essential components in various optical systems. The authors present a concept and simulations of a four‐section, widely tunable GaAs‐based sampled‐grating (SG) distributed‐Bragg reflector (DBR) laser emitting at 976 nm. This work includes the design approach of the SG reflectors and the simulation of the behaviour of the modes in the active cavity during the wavelength tuning process. Parameters such as the lasing wavelength, threshold current and the gain of the lasing and of the adjacent side modes during the tuning are presented. The numerical results presented suggest a tunability of at least 17 nm, with a threshold current change of only 2.5 mA and single‐mode operation over the entire tuning range, without the need of simultaneous adjustments of the phase section. Finally, the authors present early experimental results of a developed GaAs‐based vertical structure, providing a high coupling coefficient of , thus suitable for implementation of an SG‐DBR laser design.
Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra
Authors: Elyajouri M. , Lallement R. , Monreal-Ibero A. , Capitanio L. , Cox N. L. J.
Published: January 2017

Aims. Information on the existence and properties of diffuse interstellar bands (DIBs) outside the optical domain is still limited. Additional infra-red (IR) measurements and IR-optical correlative studies are needed to constrain DIB carriers and locate various absorbers in 3D maps of the interstellar matter.

Methods. We extended our study of H-band DIBs in Apache Point Observatory Galactic Evolution Experiment (APOGEE) Telluric Standard Star (TSS) spectra. We used the strong λ15273 band to select the most and least absorbed targets. We used individual spectra of the former subsample to extract weaker DIBs, and we searched the two stacked series for differences that could indicate additional bands. High-resolution NARVAL and SOPHIE optical spectra for a subsample of 55 TSS targets were additionally recorded for NIR/optical correlative studies.

Results. From the TSS spectra we extract a catalog of measurements of the poorly studied λλ15617, 15653, and 15673 DIBs in ≃300 sightlines, we obtain a first accurate determination of their rest wavelength and constrained their intrinsic width and shape. In addition, we studied the relationship between these weak bands and the strong λ15273 DIB. We provide a first or second confirmation of several other weak DIBs that have been proposed based on different instruments, and we add new constraints on their widths and locations. We finally propose two new DIB candidates.

Conclusions. We compared the strength of the λ15273 absorptions with their optical counterparts λλ5780, 5797, 6196, 6283, and 6614. Using the 5797–5780 ratio as a tracer of shielding against the radiation field, we showed that the λ15273 DIB carrier is significantly more abundant in unshielded (σ-type) clouds, and it responds even more strongly than the λ5780 band carrier to the local ionizing field.
Anaerobic Strength and Power in Master Athletes
Authors: Gacesa Jelena
Published: January 2017

The study compared anaerobic capacity and power in master athletes of different ages, and correlated 2 different anaerobic tests. The study was conducted on 60 male athletes: group I 30–35 years (n1=35, age 32.23±1.53 y), group II 35–45 years (n2=15, age 39.17±3.60 y), group III above 46 years (n3=10, age 52.13±4.50 y). The Wingate anaerobic test and ergometry of elbow flexors, elbow extensors, and knee extensors were performed. Average peak anaerobic power (PP) in group I was 692.94±216.53 W, in group II 593.40±185.91 W, non-significantly lower by 14.4% (p>0.05). In group III, PP was 381.50±117.62 W, significantly lower by 44.9% when compared with group I (p≤0.001). Ergometry parameter of muscle strength and power showed greater decline with age (up to 32.3%) in comparison with contraction velocity (up to 14.1%). Significant correlation was registered between PP and ergometric parameter power for knee extensors (KE) (PP/KE power: r was 0.59 in group I, 0.85 in group II, and 0.90 in group III, p≤0.05). Master athletes represent an interesting population for studying the chronic effects of physical activity on functional capacity changes during ageing. Strength parameters “age” in different fashion, because the contraction velocity parameter is less influenced than strength by the muscle alterations with increasing age.
Contractivity properties of a quantum diffusion semigroup
Authors: Datta Nilanjana , Pautrat Yan , Rouzé Cambyse
Published: January 2017

We consider a quantum generalization of the classical heat equation and study contractivity properties of its associated semigroup. We prove a Nash inequality and a logarithmic Sobolev inequality. The former leads to an ultracontractivity result. This in turn implies that the largest eigenvalue and the purity of a state with positive Wigner function, evolving under the action of the semigroup, decrease at least inverse polynomially in time, while its entropy increases at least logarithmically in time.
Stability analysis of dissolution-driven convection in porous media
Authors: Emami-Meybodi Hamid
Published: January 2017

We study the stability of dissolution-driven convection in the presence of a capillary transition zone and hydrodynamic dispersion in a saturated anisotropic porous medium, where the solute concentration is assumed to decay via a first-order chemical reaction. While the reaction enhances stability by consuming the solute, porous media anisotropy, hydrodynamic dispersion, and capillary transition zone destabilize the diffusive boundary layer that is unstably formed in a gravitational field. We perform linear stability analysis, based on the quasi-steady-state approximation, to assess critical times, critical wavenumbers, and neutral stability curves as a function of anisotropy ratio, dispersivity ratio, dispersion strength, material parameter, Bond number, Damköhler number, and Rayleigh number. The results show that the diffusive boundary layer becomes unstable in anisotropic porous media where both the capillary transition zone and dispersion are considered, even if the geochemical reaction is significantly large. Using direct numerical simulations, based on the finite difference method, we study the nonlinear dynamics of the system by examining dissolution flux, interaction of convective fingers, and flow topology. The results of nonlinear simulations confirm the predictions from the linear stability analysis and reveal that the fingering pattern is significantly influenced by combined effects of reaction, anisotropy, dispersion, and capillarity. Finally, we draw conclusions on implications of our results on carbon dioxide sequestration in deep saline aquifers.
Water-driven actuation of Ornithoctonus huwena spider silk fibers
Authors: Lin Shuyuan , Zhu Jia , Li Xinming , Guo Yang , Fang Yaopeng , Cheng Huanyu , Zhu Hongwei
Published: January 2017

Spider silk possesses remarkable mechanical properties and can lift weight effectively. Certain kinds of spider silk have unique response to liquid, especially water, because of their hydrophilic proteins, β-sheet characters, and surface structure. The Ornithoctonus huwena (O. huwena) spider is a unique species because it can be bred artificially and it spins silk whose diameter is in nanometer scale. In this work, we report the “shrink–stretch” behavior of the O. huwena spider silk fibers and show how they can be actuated by water to lift weight over long distance, at a fast speed, and with high efficiency. We further rationalize this behavior by analyzing the mechanical energy of the system. The lifting process is energy-efficient and environmentally friendly, allowing applications in actuators, biomimetic muscles, or hoisting devices.
The role of hydrophobic silane coating on Si stamps in nanoimprint lithography
Authors: Amirsadeghi Alborz , Brumfield Lance , Choi Junseo , Brown Emily , Lee Jae Jong , Park Sunggook
Published: January 2017

Hydrophobic silane coatings have been successfully applied to the surface of Si stamps to improve demolding in nanoimprint lithography (NIL). However, the role of the silane coating has only been studied either indirectly, by measuring adhesion or friction coefficients for Si and substrate surfaces without patterns, or collectively, by measuring the overall demolding force that does not differentiate contributions of friction dissipation, stored elastic energy, and adhesion. Here, for the first time, we present experimental evidence on the role of the silane coating in improving demolding in UV-NIL by using different silane coatings. The silane coatings were characterized by x-ray photoelectron spectroscopy, water contact angle, and friction force measurements. Then, the work of demolding was systematically measured for different silane coatings using stamps with the same micropattern but different pattern depths. Comparison of the results to the theoretical model developed for fiber-matrix debonding energy by Sutcu and Hillig [Acta Metall. Mater. 38(12), 2653–2662] indicated that with a hydrophobic silane coating, the main parameter contributing to overall demolding work shifts from adhesion to stored elastic energy and frictional dissipation as surface adhesion keeps decreasing. The results confirm that the main role of the silane coating in reducing the demolding is to reduce surface adhesion rather than friction at the stamp/substrate interface.
Enhanced thermal stability of Ti/TiO2/n-Ge contacts through plasma nitridation of TiO2 interfacial layer
Authors: Biswas Dipankar , Biswas Jayeeta , Ghosh Sayantan , Wood Bingxi , Lodha Saurabh
Published: January 2017

This work demonstrates a solution to the problem of increase in Schottky barrier height (ϕB) with thermal annealing (thermal instability) in unpinned (low ϕB) Ti/TiO2/n-Ge metal-interfacial layer (IL)-semiconductor (MIS) contacts through plasma nitridation of the TiO2 layer. Unlike TiO2, unpinned (ϕB = 0.09 eV) TiOxNy contacts are thermally stable for anneals up to 30 min at 400 °C. The thermal stability improves with increasing nitrogen concentration ([N], 2.5–9.5%) and is independent of thickness (2–5 nm) for [N] = 9.5%. Additionally, the plasma nitridation process is shown to increase the oxygen vacancy concentration (n-type doping) and reduce the ϕB dependence on TiOxNy thickness in unannealed TiOxNy contacts. Enhanced thermal stability is attributed to the incorporated nitrogen acting as a diffusion barrier that prevents contact pinning through reduction of the TiO2 layer by contact metal during the anneal, as well as preserves the amorphous nature of the IL along with its fixed charge and interfacial dipoles that contribute to ϕB reduction.
One-bead coarse-grained model for RNA dynamics
Authors: Villada-Balbuena Mario , Carbajal-Tinoco Mauricio D.
Published: January 2017

We present a revised version of a coarse-grained model for RNA dynamics. In such approach, the description of nucleotides is reduced to single points that interact between them through a series of effective pair potentials that were obtained from an improved analysis of RNA structures from the Protein Data Bank. These interaction potentials are the main constituents of a Brownian dynamics simulation algorithm that allows to perform a variety of tasks by taking advantage of the reduced number of variables. Such tasks include the prediction of the three-dimensional configuration of a series of test molecules. Moreover, the model permits the inclusion of effective magnesium ions and the ends of the RNA chains can be pulled with an external force to study the process of unfolding. In spite of the simplicity of the model, we obtain a good agreement with the experimental results.
Small polaron hopping conduction mechanism in LiFePO4 glass and crystal
Authors: Banday Azeem , Murugavel Sevi
Published: January 2017

The optimization of a cathode material is the most important criterion of lithium ion battery technology, which decides the power density. In order to improve the rate capability, a cathode material must possess high electronic and ionic conductivities. Therefore, it is important to understand the charge transport mechanism in such an advanced cathode material in its intrinsic state before modifying it by various means. In this work, we report the thermal, structural, and electrical conductivity studies on lithium iron phosphate, LiFePO4, both in its polycrystalline (LFPC) and glassy (LFPG) counterpart states. The vibrational spectroscopic measurements reveal the characteristic vibrational modes, which are the intrinsic part of LFPC, whereas in LFPG, the phonon modes become broader and overlap with each other due to the lattice disorder. The electrical conductivity measurements reveal that LFPG exhibits a higher polaronic conductivity of 1.6 orders than the LFPC sample. The temperature dependent dc conductivity has been analyzed with the Mott model of polarons and reveals the origin of enhanced polaronic conductivity in LFPG. Based on the analysis, the enhanced polaronic conductivity in LFPG has been attributed to the combined effect of reduced hopping length, decreased activation energy, and enhanced polaron concentration.
3.5-μm radius race-track microlasers operating at room temperature with 1.3-μm quantum dot active region
Authors: Kryzhanovskaya N. V. , Polubavkina Yu. S. , Scherbak S. A. , Moiseev E. I. , Zhurikhina V. V. , Zubov F. I. , Lipovskii A. A. , Kulagina M. M. , Troshkov S. I. , Zadiranov Yu. M. , Maximov M. V. , Zhukov A. E.
Published: January 2017

We present detailed studies of optically pumped InAs/InGaAs quantum dot based racetrack microlasers with 3.5-μm bend radius operating at room temperature. Q factor over 8000 and room temperature threshold power in the mW-range were achieved in the racetrack microlasers with straight section length ranging from 0 to 4 μm. A systematic investigation of the influence of the racetrack straight section length on spatial distribution of optical modes is presented. The microcavity eigenmodes and electromagnetic field distribution calculated by means of three-dimensional numerical simulation demonstrate a good agreement with the experimental results obtained by micro-photoluminescence and scanning near-field optical microscopy. The racetracks demonstrate zigzagging behavior of the modes inside the cavity and the energy switching between the radial maxima in second-order modes. Higher-order modes are found to be suppressed in micro-photoluminescence spectra.
Aptamer strategy for ATP detection on nanocrystalline diamond functionalized by a nitrogen and hydrogen radical beam system
Authors: Suaebah E. , Seshimo Y. , Shibata M. , Kono S. , Hasegawa M. , Kawarada H.
Published: January 2017

Here, we report a novel method for micropatterning oligonucleotides on the diamond surface via forming amine groups on the diamond surface by nitrogen/hydrogen radical treatment. The covalent bonding of the supporting oligonucleotide and characterization of an immobilized hybridized oligonucleotide with Cy5 modification were investigated by fluorescence microscopy. To investigate the effectiveness of nitrogen/hydrogen radical treatment for amine termination, two types of radical treatment were used: hydrogen/nitrogen radical treatment and pure nitrogen radical treatment. From the results, hydrogen/nitrogen radical treatment produces amine (NH2) termination on the diamond surface. The effect of amine termination was investigated by immobilization of single-stranded DNA via amide bonding between surface NH2 groups and COOH groups terminating the DNA. The immobilized single-stranded DNA (supporting DNA), which has a complementary relationship with the adenosine triphosphate (ATP) aptamer (DNA), hybridizes with the aptamer with attached fluorescence dye. When ATP molecules approach the double-stranded DNA, the aptamer forms a close relationship with the supporting DNA and combines with ATP. ATP detection was effectively carried out by reduction of fluorescence.
Elliptically polarized modes in relativistic magnetized spin quantum plasma
Authors: Habibi M. , Mendonca J. T. , Ghamari F.
Published: January 2017

The influence of relativistic correction on the propagation properties of a high-frequency range of the elliptically polarized extraordinary electromagnetic (EP-X-EM) waves in the magnetized spin quantum plasma (MSQP) is investigated by a quantum magneto hydrodynamics model. In such a situation, the relativistic effect becomes particularly noticeable in the presence of a very strong external magnetic field B0≥BQ≡4.4138×109 T and a highly dense plasma n0≫nQ≃1032 m−3 where BQ and nQ are the quantum critical magnetic field strength and electron density, respectively. For comparing with a non-relativistic regime, a new dispersion relation that extends the classical EP-X-EM waves to the quantum relativistic context is derived. Furthermore, the cut-off and resonance frequencies of this type of waves are also obtained, allowing us to define the pass and stop bands where waves can propagate in the plasma. As a new result of our work, it is found that the relativistic effect can lead to reduction in the group velocities of these waves through a MSQP. The paper discusses a number of consequential results that are useful in understanding the propagation properties of such waves in dense astrophysical bodies as well as intense laser-solid density plasma interaction experiments.
Dust ion acoustic solitary structures in presence of nonthermally distributed electrons and positrons
Authors: Paul Ashesh , Bandyopadhyay Anup , Das K. P.
Published: January 2017

The purpose of this paper is to extend the recent work of Paul and Bandyopadhyay [Astrophys. Space Sci. 361, 172 (2016)] on the existence of different dust ion acoustic solitary structures in an unmagnetized collisionless dusty plasma consisting of negatively charged static dust grains, adiabatic warm ions, nonthermal electrons, and isothermal positrons in a more generalized form by considering nonthermal positrons instead of isothermal positrons. The present system supports both positive and negative potential double layers, coexistence of solitary waves of both polarities, and positive potential supersolitons. The qualitative and quantitative changes in existence domains of different solitary structures, which occur in the presence of nonthermal positrons, have been presented in comparison with the results of Paul and Bandyopadhyay [Astrophys. Space Sci. 361, 172 (2016)]. The formation of supersoliton structures and their limitations has been analyzed with the help of phase portraits of the dynamical system corresponding to the dust ion acoustic solitary structures. Phase portrait analysis clearly indicates a smooth transition between solitons and supersolitons.
Detection of individual iron-oxide nanoparticles with vertical and lateral sensitivity using domain wall nucleation in CoFeB/Pt nanodevices
Authors: Wells James , Fernández Scarioni Alexander , Schumacher Hans W. , Cox David , Mansell Rhodri , Cowburn Russell , Kazakova Olga
Published: January 2017

We present new studies of the characteristics and detection ability of nanoscale sensors based on domain wall nucleation within perpendicularly magnetised ultrathin CoFeB/Pt films. A combination of MFM imaging and anomalous Hall effect transport measurements were used to verify and characterise the behaviour of fabricated devices. After initial characterisation, the influence of magnetic nanoparticles on device behaviour was studied using individual iron oxide (FeOx) particles mounted on modified atomic force microscopy probes. We demonstrate the successful detection of particles ranging in diameter between 2.8 μm and 100 nm. In the case of the 2.8 μm particle, we have mapped the signal amplitude produced at a variety of distances from the sensor. We find that the particle’s influence may be detected at separations up to 700 nm. Furthermore, we demonstrate a method for resolving the location of a particle with respect to the centre of the device, providing a lateral sensing ability.
Micromagnetic simulation of domain wall propagation along meandering magnetic strip with spatially modulated material parameters
Authors: Zhang Z. , Tanaka T. , Matsuyama K.
Published: January 2017

Feasibility of two-dimensional propagation of the domain wall (DW) was investigated by micromagnetic simulations. Successful bit-by-bit propagation of the DW was demonstrated in a designed meandering magnetic strip with periodic material parameter modulation, used as DW pinning sites (PSs). The DW was successively shifted along the straight part and around the corner with a spin polarized current pulses with 1 ns-width, 3 ns-interval and same amplitude. A practical current amplitude margin (30 % of mid value) was achieved by analyzing the energy landscape around the meandering corner and optimizing the location of the PSs, which energy barrier height assures a thermal stability criterion (>60 kBT).
Electrostatically actuated membranes made from silica thin films
Authors: Stout John M. , Welker Taylor M. , Hawkins Aaron R.
Published: January 2017

We present a method for fabricating flexible nano-scale membranes using surface micromachining and silica thin films. Standard microfabrication techniques are used, and the membrane can be moved using electrostatic forces. The degree of deflection is set by an applied voltage, and the devices can be fully collapsed (100 nm movement) by applying approximately 150 V. Deflection tests were performed using an optical profilometer when the area under the membrane was filled with air and water.
Spin pumping and inverse spin Hall effect in antiferromagnetic exchange coupled [Co/Ru/Co]/Pt heterostructures
Authors: Avilés-Félix L. , Butera A. , Gómez J. E.
Published: January 2017

We report the observation of spin pumping and inverse spin Hall effects in antiferromagnetically coupled [Co/Ru/Co]/Pt heterostructures. The “spin-flop” magnetization process observed in antiferromagnetically exchange coupled Co layers combined with spin pumping and inverse spin Hall effects allowed us to detect both transversal and longitudinal charge accumulations. By controlling the exchange coupling strength and the spin flop transition in the magnetization process, it was possible to produce spin currents polarized in different directions.
Endothelial Wnt/β-catenin signaling reduces immune cell infiltration in multiple sclerosis
Authors: Lengfeld Justin E. , Lutz Sarah E. , Smith Julian R. , Diaconu Claudiu , Scott Cameron , Kofman Sigal B. , Choi Claire , Walsh Craig M. , Raine Cedric S. , Agalliu Ilir , Agalliu Dritan
Published: January 2017

Significance

Endothelial cells (ECs) in the CNS form a unique blood–brain barrier (BBB) that is broken down in multiple sclerosis (MS). New therapies are sorely needed to restore BBB function in this disease. The wingless integrated MMTV (Wnt)/β-catenin pathway, which is essential for barrier formation, is activated in CNS ECs in MS and the animal model experimental autoimmune encephalomyelitis. When this pathway is inhibited in ECs before disease onset, mice develop more severe disease, with more immune cells entering the CNS owing to increased levels of proteins that promote interactions of immune cells with blood vessels and transport across vessels. Our findings suggest that pharmacologic enhancement of Wnt signaling may be helpful to limit BBB damage and CNS immune cell infiltration in MS.
Nucleotide-dependent switch in proteasome assembly mediated by the Nas6 chaperone
Authors: Li Frances , Tian Geng , Langager Deanna , Sokolova Vladyslava , Finley Daniel , Park Soyeon
Published: January 2017

Significance

The proteasome is a molecular machine essential for protein degradation. The proteasome holoenzyme assembles from the association of three subcomplexes: lid, base, and core particle (CP). The base binding chaperones, Nas6, Rpn14, Hsm3, and Nas2, antagonize base–CP interaction. Here, we demonstrate that the Nas6 chaperone also obstructs base–lid association. The specificity of Nas6 activity is determined by the nucleotide state of the base. When ATP hydrolysis is blocked, Nas6 interferes with base–lid association. In contrast, under conditions of ATP hydrolysis, Nas6 interferes with base–CP association. Nas6 uses the mechanism of steric hindrance at both major interfaces of the proteasome: base–lid and base–CP. We demonstrate that Nas6 provides a dual mechanism to control proteasome assembly.
A mechanism for the induction of type 2 immune responses by a protease allergen in the genital tract
Authors: Oh Ji Eun , Oh Dong Sun , Jung Hi Eun , Lee Heung Kyu
Published: January 2017

Significance

In contrast to other T helper cell populations, the manner in which type 2 immune responses are induced within the female genital tract remains unknown. For these reasons, we show that IL-33 derived from the vaginal epithelium plays a critical role in the generation of type 2 immunity, likely through the activation of type 2 innate lymphoid cells via the myeloid differentiation primary response gene 88 (MyD88) signaling pathway. In addition, intravaginal papain-induced type 2 immunity is dependent on a specific dendritic cell subset that is controlled by interferon regulatory factor 4 (IRF4). These findings provide insight into the mechanisms by which the secretion of proteases from opportunistic pathogens in susceptibility to various sexually transmitted pathogens may induce type 2 immunity within the female genital tract.
Siberian Arctic black carbon sources constrained by model and observation
Authors: Winiger Patrik , Andersson August , Eckhardt Sabine , Stohl Andreas , Semiletov Igor P. , Dudarev Oleg V. , Charkin Alexander , Shakhova Natalia , Klimont Zbigniew , Heyes Chris , Gustafsson Örjan
Published: January 2017

Significance

A successful mitigation strategy for climate warming agents such as black carbon (BC) requires reliable source information from bottom-up emission inventory data, which can only be verified by observation. We measured BC in one of the fastest-warming and, at the same time, substantially understudied regions on our planet, the northeastern Siberian Arctic. Our observations, compared with an atmospheric transport model, imply that quantification and spatial allocation of emissions at high latitudes, specifically in the Russian Arctic, need improvement by reallocating emissions and significantly shifting source contributions for the transport, domestic, power plant, and gas flaring sectors. This strong shift in reported emissions has potentially considerable implications for climate modeling and BC mitigation efforts.
Single polysaccharide assembly protein that integrates polymerization, termination, and chain-length quality control
Authors: Williams Danielle M. , Ovchinnikova Olga G. , Koizumi Akihiko , Mainprize Iain L. , Kimber Matthew S. , Lowary Todd L. , Whitfield Chris
Published: January 2017

Significance

Glycosyltransferase enzymes synthesize complex sugar-containing macromolecules that play pivotal roles in the biology of all cells. Bacteria produce a vast range of glycoconjugate structures that frequently dictate host–pathogen interactions. The composition and chain length of bacterial glycans are both important for biological function, yet the mechanisms for chain-length determination are generally poorly understood. Here, we describe a remarkable family of proteins in which each member contains multiple glycosyltransferase modules (often representing new glycosyltransferase families) for glycan polymerization and chain termination. The polymerase and terminator activities are separated by a molecular ruler that establishes product length. The modularity of these proteins provides an adaptable platform for generating antigenic diversity in nature and potential new strategies for glycoengineering.
How electron two-stream instability drives cyclic Langmuir collapse and continuous coherent emission
Authors: Che Haihong , Goldstein Melvyn L. , Diamond Patrick H. , Sagdeev Roald Z.
Published: January 2017

Significance

Electron two-stream instability (ETSI) is believed to be responsible for the radio bursts observed in both the solar corona and interplanetary medium. What nonlinear kinetic processes self-consistently reconcile the several orders of magnitude difference between the short linear saturation time scale of ETSI and the long duration of bursts is fundamental in plasma turbulence and has remained unsolved for nearly 50 y. Using massive particle-in-cell simulations, we find a self-consistent and complete nonlinear solution to this problem.
Efficient in vivo gene editing using ribonucleoproteins in skin stem cells of recessive dystrophic epidermolysis bullosa mouse model
Authors: Wu Wenbo , Lu Zhiwei , Li Fei , Wang Wenjie , Qian Nannan , Duan Jinzhi , Zhang Yu , Wang Fengchao , Chen Ting
Published: January 2017

Significance

The prokaryotic CRISPR/Cas9 system has recently been applied in genome editing in mammalian cells with the potential to bring curative therapies to patients with genetic diseases. However, efficient in vivo delivery of this machinery remains challenging for most tissue types. We now developed a method to locally deliver Cas9/sgRNA ribonucleoproteins into the skin of postnatal mice, which was used to correct genetic defects in skin stem cells of postnatal recessive dystrophic epidermolysis bullosa (RDEB) mice. Our study provides proof-of-principle evidence that Cas9/sgRNA ribonucleoprotein-based gene therapies can be applied to restore collagen VII protein function in postnatal RDEB mice, suggesting that the Cas9/sgRNA ribonucleoprotein-based gene therapy may offer curative treatment for RDEB and other genetic disorders.
Dynamics of GreB-RNA polymerase interaction allow a proofreading accessory protein to patrol for transcription complexes needing rescue
Authors: Tetone Larry E. , Friedman Larry J. , Osborne Melisa L. , Ravi Harini , Kyzer Scotty , Stumper Sarah K. , Mooney Rachel A. , Landick Robert , Gelles Jeff
Published: January 2017

Significance

RNA polymerases (RNAPs) from all organisms share a common form of regulation: Regulator proteins bind in a conserved “secondary channel” pore on RNAP and alter RNAP activity. In bacteria, multiple such regulators are present in the same cell, but how these bind without mutual interference is unclear. We directly observed binding of single molecules of secondary channel protein GreB to RNAP transcription complexes. Unexpectedly, GreB was not selectively recruited to RNAPs requiring its transcript proofreading function. Instead, GreB transiently bound to multiple types of complexes, eventually finding via random search RNAPs that require its activity. The observations suggest a paradigm by which a regulator can act while minimizing obstruction of a binding site that must be shared with other proteins.
Enteroviruses infect human enteroids and induce antiviral signaling in a cell lineage-specific manner
Authors: Drummond Coyne G. , Bolock Alexa M. , Ma Congrong , Luke Cliff J. , Good Misty , Coyne Carolyn B.
Published: January 2017

Significance

Enteroviruses are a leading source of human infections worldwide and are primarily transmitted by the fecal–oral route. However, very little is known regarding the events associated with enterovirus infection of the human gastrointestinal tract. Here, we used a primary stem cell-derived enteroid model to interrogate the susceptibility of human enteroids to a panel of enteroviruses and to determine the antiviral signaling pathways induced in response to infection. Our study provides important insights into the mechanisms associated with enteroviral infections of the human gastrointestinal tract.
Simple stochastic dynamical models capturing the statistical diversity of El Niño Southern Oscillation
Authors: Chen Nan , Majda Andrew J.
Published: January 2017

Significance

The El Niño Southern Oscillation (ENSO) has significant impact on global climate and seasonal prediction. A simple modeling framework is developed here that automatically captures the statistical diversity of ENSO. In addition to simulating different types of El Niño and La Niña with realistic features, the model succeeds in capturing both the variance and the non-Gaussian statistical properties in different Niño regions spanning the Pacific. Particularly, the observed episode during the 1990s, where a 5-y central Pacific El Niño is followed by a super El Niño and then a La Niña, is reproduced by the model. Key features of the model are state-dependent stochastic wind bursts and nonlinear advection of sea-surface temperature that allow effective transitions between different ENSO states.
Influence of iron doping on tetravalent nickel content in catalytic oxygen evolving films
Authors: Li Nancy , Bediako D. Kwabena , Hadt Ryan G. , Hayes Dugan , Kempa Thomas J. , von Cube Felix , Bell David C. , Chen Lin X. , Nocera Daniel G.
Published: January 2017

Significance

Iron-doped nickel oxide films are the most active nonnoble metal oxygen evolution reaction (OER) catalysts in alkaline electrolyte. Since Corrigan’s original discovery of enhanced activity with Fe doping in nickel oxides, the chemical basis for this synergy remains unclear. Recent studies suggest iron to assume a high valent oxidation state, thus promoting OER. We provide evidence for an alternative role of Fe3+as a Lewis acid in the host nickel oxide. We observe that Fe3+promotes the formation of Ni4+, which leads to enhanced catalytic activity. This result is consistent with Fe3+to be one of the strongest Lewis acidic metals by any measure of Lewis acidity, including hard–soft acid base theory, metal ion pKas, and chemical inertness.
Targeting IRE1 with small molecules counteracts progression of atherosclerosis
Authors: Tufanli Ozlem , Telkoparan Akillilar Pelin , Acosta-Alvear Diego , Kocaturk Begum , Onat Umut Inci , Hamid Syed Muhammad , Çimen Ismail , Walter Peter , Weber Christian , Erbay Ebru
Published: January 2017

Significance

Endoplasmic reticulum (ER) stress is linked to the development of complex metabolic diseases, including diabetes, obesity, and atherosclerosis. Irremediable ER stress can push the unfolded protein response (UPR) toward proinflammatory and proapoptotic signaling. The need to dissociate the adaptive UPR responses from its destructive outputs has become a major challenge for therapeutic strategies aimed at mitigating ER stress that is often observed in chronic diseases. Our findings show that inositol-requiring enzyme 1 (IRE1) plays a critical role in metaflammation and that administering IRE1-specific inhibitors to hyperlipidemic mice counteracts atherosclerosis progression.
IgD class switching is initiated by microbiota and limited to mucosa-associated lymphoid tissue in mice
Authors: Choi Jin Huk , Wang Kuan-wen , Zhang Duanwu , Zhan Xiaowei , Wang Tao , Bu Chun-Hui , Behrendt Cassie L. , Zeng Ming , Wang Ying , Misawa Takuma , Li Xiaohong , Tang Miao , Zhan Xiaoming , Scott Lindsay , Hildebrand Sara , Murray Anne R. , Moresco Eva Marie Y. , Hooper Lora V. , Beutler Bruce
Published: January 2017

Significance

Immunoglobulins exist in several forms, or isotypes, that carry out distinct effector functions. During an antibody response, B cells can switch their immunoglobulin isotype through the process of class-switch recombination (CSR). CSR to IgD is a rare event compared with CSR to other isotypes, and its regulation is poorly understood. Here we report that mice lacking the DNA damage-response protein 53BP1 display a hyper-IgD syndrome despite deficiencies of other immunoglobulin classes. By studying these mice, we discovered that CSR to IgD in 53BP1 mutant mice and in wild-type mice depends on an intact microbiome and Toll-like receptor signaling, and is anatomically confined to B cells of mucosa-associated lymphoid tissues.
E3 ubiquitin ligase Mule targets β-catenin under conditions of hyperactive Wnt signaling
Authors: Dominguez-Brauer Carmen , Khatun Rahima , Elia Andrew J. , Thu Kelsie L. , Ramachandran Parameswaran , Baniasadi Shakiba P. , Hao Zhenyue , Jones Lisa D. , Haight Jillian , Sheng Yi , Mak Tak W.
Published: January 2017

Significance

Wnt signaling, named after the secreted proteins that bind to cell surface receptors to activate the pathway, is crucial for normal cell functions, and its deregulation can culminate in cancer. Several surveillance mechanisms have evolved as a precautionary measure to ensure proper development and the avoidance of cancer. Here we reveal that the E3 ubiquitin ligase Mule can target β-catenin for degradation to stop the Wnt signal during constitutive activation. Significantly, our data indicate that a combined loss of
Mule
and
Apc
accelerates the conversion of normal intestinal stem cells into cancer stem cells, paving the way to colorectal cancer development. It may be possible to use this knowledge to manipulate Mule, β-catenin, or Wnt pathway functions to reduce cancer initiation.
Role of active site conformational changes in photocycle activation of the AppA BLUF photoreceptor
Authors: Goyal Puja , Hammes-Schiffer Sharon
Published: January 2017

Significance

Photoreceptor proteins play a critical role in the light regulation of physiologically essential processes, including color vision, circadian rhythms, and photomovement. Photoexcitation of a chromophore bound to the photoreceptor protein leads to local conformational changes that propagate to distal regions of the protein and thereby drive vital chemical and physical changes. Understanding the fundamental mechanisms of these proteins is important for engineering systems that use light to control biological processes with high spatiotemporal resolution. In this study, computer simulations of a photoreceptor protein provide valuable insights into the active site conformations prior to and following photoexcitation. The position of a certain tryptophan residue, as well as the hydrogen-bonding pattern, is shown to impact the activation and efficiency of this photoreceptor.
Creatine maintains intestinal homeostasis and protects against colitis
Authors: Turer Emre , McAlpine William , Wang Kuan-wen , Lu Tianshi , Li Xiaohong , Tang Miao , Zhan Xiaoming , Wang Tao , Zhan Xiaowei , Bu Chun-Hui , Murray Anne R. , Beutler Bruce
Published: January 2017

Significance

The present study used a forward genetic approach to identify new causative mutations in an environmentally sensitized screen for colitis. A candidate mutation in
Gatm
, verified by CRISPR/Cas9 targeting, demonstrated the need for rapid replenishment of cytoplasmic ATP within colonic epithelial cells to restore barrier integrity. This environmentally specified requirement for energy to avert colitis suggests a new category of mutations with the potential to cause inflammatory bowel disease.