4,092 research outputs found
Cladding of Mg alloy with Zr based BMG Alloy
In the present work, an attempt has been made to clad AZ31 magnesium alloy with Zr-based bulk metallic glassy alloy (Vit-1), by casting method. The interface studies conducted using SEM-EDS line scan indicate that a good bond is formed at the clad interface of Zr and Mg. And the mechanism involved is discussed herein.110Ysciescopu
Highly Conductive Graphene/Ag Hybrid Fibers for Flexible Fiber-Type Transistors
Mechanically robust, flexible, and electrically conductive textiles are highly suitable for use in wearable electronic applications. In this study, highly conductive and flexible graphene/Ag hybrid fibers were prepared and used as electrodes for planar and fiber-type transistors. The graphene/Ag hybrid fibers were fabricated by the wet-spinning/drawing of giant graphene oxide and subsequent functionalization with Ag nanoparticles. The graphene/Ag hybrid fibers exhibited record-high electrical conductivity of up to 15,800 S cm(-1). As the graphene/Ag hybrid fibers can be easily cut and placed onto flexible substrates by simply gluing or stitching, ion gel-gated planar transistors were fabricated by using the hybrid fibers as source, drain, and gate electrodes. Finally, fibertype transistors were constructed by embedding the graphene/Ag hybrid fiber electrodes onto conventional polyurethane monofilaments, which exhibited excellent flexibility (highly bendable and rollable properties), high electrical performance (mu(h) = 15.6 cm(2) V-1 s(-1), I-on/I-off > 10(4)), and outstanding device performance stability (stable after 1,000 cycles of bending tests and being exposed for 30 days to ambient conditions). We believe that our simple methods for the fabrication of graphene/Ag hybrid fiber electrodes for use in fiber-type transistors can potentially be applied to the development all-organic wearable devices.111912Ysciescopu
Chicken genome analysis reveals novel genes encoding biotin-binding proteins related to avidin family
BACKGROUND: A chicken egg contains several biotin-binding proteins (BBPs), whose complete DNA and amino acid sequences are not known. In order to identify and characterise these genes and proteins we studied chicken cDNAs and genes available in the NCBI database and chicken genome database using the reported N-terminal amino acid sequences of chicken egg-yolk BBPs as search strings. RESULTS: Two separate hits showing significant homology for these N-terminal sequences were discovered. For one of these hits, the chromosomal location in the immediate proximity of the avidin gene family was found. Both of these hits encode proteins having high sequence similarity with avidin suggesting that chicken BBPs are paralogous to avidin family. In particular, almost all residues corresponding to biotin binding in avidin are conserved in these putative BBP proteins. One of the found DNA sequences, however, seems to encode a carboxy-terminal extension not present in avidin. CONCLUSION: We describe here the predicted properties of the putative BBP genes and proteins. Our present observations link BBP genes together with avidin gene family and shed more light on the genetic arrangement and variability of this family. In addition, comparative modelling revealed the potential structural elements important for the functional and structural properties of the putative BBP proteins
Delayed Lubricant Depletion of Slippery Liquid Infused Porous Surfaces Using Precision Nanostructures
Slippery liquid infused porous surfaces (SLIPS) are an important class of repellent materials, comprising micro/nanotextures infused with a lubricating liquid. Unlike superhydrophobic surfaces, SLIPS do not rely on a stable air-liquid interface and thus can better manage low surface tension fluids, are less susceptible to damage under physical stress, and are able to self-heal. However, these collective properties are only efficient as long as the lubricant remains infused, which has proved challenging. We hypothesized that, in comparison to a nanohole and nanopillar morphology, the "hybrid" morphology of a hole within a nanopillar, namely a nanotube, would be able to retain and redistribute lubricant more effectively, owing to capillary forces trapping a reservoir of lubricant within the tube, while lubricant between tubes can facilitate redistribution to depleted areas. By virtue of recent fabrication advances in spacer defined intrinsic multiple patterning (SDIMP), we fabricated an array of silicon nanotubes and equivalent arrays of nanoholes and nanopillars (pitch, 560 nm; height, 2 μm). After infusing the nanostructures (prerendered hydrophobic) with lubricant Krytox 1525, we probed the lubricant stability under dynamic conditions and correlated the degree of the lubricant film discontinuity to changes in the contact angle hysteresis. As a proof of concept, the durability test, which involved consecutive deposition of droplets onto the surface amounting to 0.5 L, revealed 2-fold and 1.5-fold enhancements of lubricant retention in nanotubes in comparison to nanopillars and nanoholes, respectively, showing a clear trajectory for prolonging the lifetime of a slippery surface
Abnormal Stop Band Behavior Induced by Rotational Resonance in Flexural Metamaterial
This paper investigates abnormal stop band behavior of resonance-based flexural elastic metamaterials under the rotational resonance motion. Due to the unique physics of flexural waves, we found that the stop band generated by the rotational resonance motion exhibits peculiar behavior which are quite different from general belief - it is shown that the negativity due to the rotational resonance does not provide any stop bands and the stop band generation due to the rotational resonance is governed by totally different band gap condition. To explain the peculiar behavior, a discrete Timoshenko beam model with both effective mass and rotational inertia as independent variables is introduced, and the wave behaviors of resonance-based flexural elastic metamaterial are precisely and fully described. The unique band gap condition, including the peculiar behavior, is derived with numerical validations. We expect our new model can provide a strong background for various flexural elastic metamaterials which can be effectively applied in various vibration devices
Macroscopic transport by synthetic molecular machines
Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with—and perform physical tasks in—the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (‘molecular shuttles’) to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.
Enhanced Supersymmetry of Nonrelativistic ABJM Theory
We study the supersymmetry enhancement of nonrelativistic limits of the ABJM
theory for Chern-Simons level . The special attention is paid to the
nonrelativistic limit (known as `PAAP' case) containing both particles and
antiparticles. Using supersymmetry transformations generated by the monopole
operators, we find additional 2 kinematical, 2 dynamical, and 2 conformal
supercharges for this case. Combining with the original 8 kinematical
supercharges, the total number of supercharges becomes maximal: 14
supercharges, like in the well-known PPPP limit. We obtain the corresponding
super Schr\"odinger algebra which appears to be isomorphic to the one of the
PPPP case. We also discuss the role of monopole operators in supersymmetry
enhancement and partial breaking of supersymmetry in nonrelativistic limit of
the ABJM theory.Comment: 22 pages, references added, version to appear in JHE
BASS. XXXV. The MBH-σ* Relation of 105 Month Swift-BAT Type 1 AGNs
We present two independent measurements of stellar velocity dispersions (sigma(star)) from the Ca II H+K lambda 3969, 3934 and Mg I b lambda 5183, 5172, 5167 region (3880-5550 angstrom) and the calcium triplet region (8350-8750 angstrom) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs; z <= 0.08) from the 105 month Swift-BAT catalog. We construct one of the largest samples of local Type 1 AGNs that have both single-epoch virial black hole mass (M-BH) estimates and sigma(star) measurements obtained from high spectral resolution data, allowing us to test the usage of such methods for supermassive black hole studies. We find that the two independent sigma(star) measurements are highly consistent with each other, with an average offset of only 0.002 +/- 0.001 dex. Comparing M-BH estimates based on broad emission lines and stellar velocity dispersion measurements, we find that the former is systematically lower by approximate to 0.12 dex. Consequently, Eddington ratios estimated through broad-line MBH determinations are similarly biased (but in the opposite way). We argue that the discrepancy is driven by extinction in the broad-line region. We also find an anticorrelation between the offset from the M-BH-sigma(star) relation and the Eddington ratio. Our sample of Type 1 AGNs shows a shallower M-BH-sigma(star) relation (with a power-law exponent of approximate to 3.5) compared with that of inactive galaxies (with a power-law exponent of approximate to 4.5), confirming earlier results obtained from smaller samples
Do Characteristics of Faces That Convey Trustworthiness and Dominance Underlie Perceptions of Criminality?
BACKGROUND: This study tested whether the 2D face evaluation model proposed by Oosterhof and Todorov can parsimoniously account for why some faces are perceived as more criminal-looking than others. The 2D model proposes that trust and dominance are spontaneously evaluated from features of faces. These evaluations have adaptive significance from an evolutionary standpoint because they indicate whether someone should be approached or avoided. METHOD: Participants rated the emotional state, personality traits, and criminal appearance of faces shown in photographs. The photographs were of males and females taken under naturalistic conditions (i.e., police mugshots) and highly controlled conditions. In the controlled photographs, the emotion display of the actor was systematically varied (happy expression, emotionally neutral expression, or angry expression). RESULTS: Both male and female faces rated high in criminal appearance were perceived as less trustworthy and more dominant in police mugshots as well as in photographs taken under highly controlled conditions. Additionally, emotionally neutral faces were deemed as less trustworthy if they were perceived as angry, and more dominant if they were morphologically mature. Systematically varying emotion displays also affected criminality ratings, with angry faces perceived as the most criminal, followed by neutral faces and then happy faces. CONCLUSION: The 2D model parsimoniously accounts for criminality perceptions. This study extends past research by demonstrating that morphological features that signal high dominance and low trustworthiness can also signal high criminality. Spontaneous evaluations regarding criminal propensity may have adaptive value in that they may help us to avoid someone who is physically threatening. On the other hand, such evaluations could inappropriately influence decision making in criminal identification lineups. Hence, additional research is needed to discover whether and how people can avoid making evaluations regarding criminality from a person's facial appearance
Scalar and vector Slepian functions, spherical signal estimation and spectral analysis
It is a well-known fact that mathematical functions that are timelimited (or
spacelimited) cannot be simultaneously bandlimited (in frequency). Yet the
finite precision of measurement and computation unavoidably bandlimits our
observation and modeling scientific data, and we often only have access to, or
are only interested in, a study area that is temporally or spatially bounded.
In the geosciences we may be interested in spectrally modeling a time series
defined only on a certain interval, or we may want to characterize a specific
geographical area observed using an effectively bandlimited measurement device.
It is clear that analyzing and representing scientific data of this kind will
be facilitated if a basis of functions can be found that are "spatiospectrally"
concentrated, i.e. "localized" in both domains at the same time. Here, we give
a theoretical overview of one particular approach to this "concentration"
problem, as originally proposed for time series by Slepian and coworkers, in
the 1960s. We show how this framework leads to practical algorithms and
statistically performant methods for the analysis of signals and their power
spectra in one and two dimensions, and, particularly for applications in the
geosciences, for scalar and vectorial signals defined on the surface of a unit
sphere.Comment: Submitted to the 2nd Edition of the Handbook of Geomathematics,
edited by Willi Freeden, Zuhair M. Nashed and Thomas Sonar, and to be
published by Springer Verlag. This is a slightly modified but expanded
version of the paper arxiv:0909.5368 that appeared in the 1st Edition of the
Handbook, when it was called: Slepian functions and their use in signal
estimation and spectral analysi
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