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Sample records for suspended nanobelt bimorph

  1. Bimorphic polymeric photomechanical actuator

    NASA Technical Reports Server (NTRS)

    Sarkisov, Sergey S. (Inventor); Curley, Michael J. (Inventor); Adamovsky, Grigory (Inventor); Sarkisov, Jr., Sergey S. (Inventor); Fields, Aisha B. (Inventor)

    2006-01-01

    A bimorphic polymeric photomechanical actuator, in one embodiment using polyvinylidene fluoride (PVDF) as a photosensitive body, transmitting light over fiber optic cables, and controlling the shape and pulse duration of the light pulse to control movement of the actuator. Multiple light beams are utilized to generate different ranges of motion for the actuator from a single photomechanical body and alternative designs use multiple light beams and multiple photomechanical bodies to provide controlled movement. Actuator movement using one or more ranges of motion is utilized to control motion to position an actuating element in three dimensional space.

  2. A piezoelectric pseudo-bimorph actuator

    NASA Astrophysics Data System (ADS)

    Shi, Huaduo; Chen, Jianguo; Liu, Guoxi; Xiao, Wenlei; Dong, Shuxiang

    2013-06-01

    We report a piezoelectric pseudo-bimorph actuator, which is made of only one single plate with interdigitated electrodes on both sides and polarized alternately in longitudinal direction. Like a bimorph actuator, it can also produce a large bending actuation based on anti-symmetrically longitudinal piezoelectric d33 strain effect under an applied electric field. The presented pseudo-bimorph actuator shows much better temperature stability than conventional piezoelectric bimorph actuators from room temperature to the depolarization temperature of the material due to lacking of interface strain loss.

  3. Morphing of Segmented Bimorph Mirrors

    NASA Astrophysics Data System (ADS)

    Rodrigues, Gonçalo; Bastaits, Renaud; Preumont, André

    2010-08-01

    Atmospheric turbulence compensation for the next generation of terrestrial telescopes (30-40 m diameter) will require deformable mirrors of increasing size and a number of actuators reaching several thousands. However, the mere extrapolation of existing designs leads to complicated and extremely expensive mirrors. This article discusses an alternative solution based on the use of segmented identical hexagonal bimorph mirrors. This allows to indefinitely increase the degree of correction while maintaining the first mechanical resonance at the level of a single segment, and shows an increase in price only proportional to the number of segments. Extensive simulations using random turbulent screens show that the segmentation produces only moderate reductions of the Strehl number, compared to a monolithic bimorph mirror with the same number of actuators (S = 0.86 instead of S = 0.89 in this study).

  4. Note: Helical nanobelt force sensors

    NASA Astrophysics Data System (ADS)

    Hwang, G.; Hashimoto, H.

    2012-12-01

    We present the fabrication and characterization of helical nanobelt force sensors. These self-sensing force sensors are based on the giant piezoresistivity of helical nanobelts. The three-dimensional helical nanobelts are self-formed from 27 nm-thick n-type InGaAs/GaAs bilayers using rolled-up techniques, and assembled onto electrodes on a micropipette using nanorobotic manipulations. The helical nanobelt force sensors can be calibrated using a calibrated atomic force microscope cantilever system under scanning electron microscope. Thanks to their giant piezoresistance coefficient (515 × 10-10 Pa-1), low stiffness (0.03125 N/m), large-displacement capability (˜10 μm), and good fatigue resistance, they are well suited to function as stand-alone, compact (˜20 μm without the plug-in support), light (˜5 g including the plug-in support), versatile and large range (˜μN) and high resolution (˜nN) force sensors.

  5. Bi nanobelts, nanocubes and their thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Wang, Wenzhong; Chen, Shuo; Huang, Jianyu; Ren, Zhifeng; Harris, T.; Chen, Gang; Dresselhaus, M.

    2006-03-01

    Highly crystallized Bi nanobelts and monodispersed nanocubes have been synthesized via a low-temperature organic solution approach, in which sodium bismuthate was reduced by ethylene glycol in the presence of poly(vinylpyrrolidone) (PVP). By changing some experimental conditions, Bi nanobelts and nanocubes have been prepared successfully. The as-prepared Bi nanobelts are single crystal with high crystallinity. The width of the nanobelts is in the range of 50-500 nanometers and the length is up to of several tens of micrometers. The as-synthesized Bi nanocubes are highly crystallized and monodispersed with edge length of 50-60 nm. The electrical, thermal, and Seebeck properties of the as-grown nanobelts were studied by a TEM-STM probe inside a high resolution TEM. The same studies were also carried out on bulk samples made by hot-press using the nanocubes.

  6. Light-Driven Polymeric Bimorph Actuators

    NASA Technical Reports Server (NTRS)

    Adamovsky, Gregory; Sarkisov, Sergey S.; Curley, Michael J.

    2009-01-01

    Light-driven polymeric bimorph actuators are being developed as alternatives to prior electrically and optically driven actuators in advanced, highly miniaturized devices and systems exemplified by microelectromechanical systems (MEMS), micro-electro-optical-mechanical systems (MEOMS), and sensor and actuator arrays in smart structures. These light-driven polymeric bimorph actuators are intended to satisfy a need for actuators that (1) in comparison with the prior actuators, are simpler and less power-hungry; (2) can be driven by low-power visible or mid-infrared light delivered through conventional optic fibers; and (3) are suitable for integration with optical sensors and multiple actuators of the same or different type. The immediate predecessors of the present light-driven polymeric bimorph actuators are bimorph actuators that exploit a photorestrictive effect in lead lanthanum zirconate titanate (PLZT) ceramics. The disadvantages of the PLZT-based actuators are that (1) it is difficult to shape the PLZT ceramics, which are hard and brittle; (2) for actuation, it is necessary to use ultraviolet light (wavelengths < 380 nm), which must be generated by use of high-power, high-pressure arc lamps or lasers; (3) it is difficult to deliver sufficient ultraviolet light through conventional optical fibers because of significant losses in the fibers; (4) the response times of the PLZT actuators are of the order of several seconds unacceptably long for typical applications; and (5) the maximum mechanical displacements of the PLZT-based actuators are limited to those characterized by low strains beyond which PLZT ceramics disintegrate because of their brittleness. The basic element of a light-driven bimorph actuator of the present developmental type is a cantilever beam comprising two layers, at least one of which is a polymer that exhibits a photomechanical effect (see figure). The dominant mechanism of the photomechanical effect is a photothermal one: absorption of

  7. Dual-use bimorph deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, M. S.; Laycock, L. C.; Bagshaw, J. M.; Rowe, D.

    2005-11-01

    Adaptive Optics (AO) is a critical underpinning technology for future optical countermeasures, laser delivery, target illumination and imaging systems. It measures and compensates for optical distortion caused by transmission through the atmosphere, resulting in the ability to deploy smaller lasers and identify targets at greater ranges. AO is also well established in ground based astronomy, and is finding applications in free space optical communications and ophthalmology. One of the key components in an AO system is the wavefront modifier, which acts on the incoming or outgoing beam to counter the effects of the atmosphere. BAE SYSTEMS ATC is developing multi-element Deformable Bimorph Mirrors (DBMs) for such applications. A traditional bimorph deformable mirror uses a set of edge electrodes outside the active area in order to meet the required boundary conditions for the active aperture. This inflicts a significant penalty in terms of bandwidth, which is inversely proportional to the square of the full mirror diameter. We have devised a number of novel mounting arrangements that reduce dead space and thus provide a much improved trade-off between bandwidth and stroke. These schemes include a novel method for providing vertical displacement at the periphery of the aperture, a method for providing a continuous compliant support underneath the bimorph mirror, and a method for providing a three point support underneath the bimorph. In all three cases, there is no requirement for edge electrodes to provide the boundary conditions, resulting in devices of much higher bandwidth. The target is to broaden the use of these types of mirror beyond the current limits of either low order/low bandwidth, to address the high order, high bandwidth systems required by long range, horizontal path applications. This paper will discuss the different mirror designs, and present experimental results for the most recently assembled mirrors.

  8. Functional oxide nanobelts - from materials to nanodevices

    NASA Astrophysics Data System (ADS)

    Lin, Zhong; Wang

    2003-11-01

    Nanowire and nanotube based materials have been demonstrated as building blocks for nanocircuits, nanosystems and nano-optoelectronics. Recently, ultra-long belt-like, quasi-one-dimensional nanostructures (so called nanobelts or nanoribbons) have been successfully synthesized for semiconducting oxides of zinc, tin, indium, cadmium and gallium, by simply evaporating the desired commercial metal oxide powders at high temperatures [1]. The as-synthesized oxide nanobelts are pure, structurally uniform, single crystalline and most of them free from dislocations; they have a rectangular-like cross-section with typical widths of 30 - 300 nm, width-to-thickness ratios of 5 - 10 and lengths of up to a few millimeters. The belt-like morphology appears to be a unique and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. Using the technique demonstrated for measuring the mechanical properties of carbon nanotubes based on in-situ transmission electron microscopy [2,3], the bending modulus of the oxide nanobelts has been measured and the nanobelt is shown to be a dual mode nanoresonator for NEMS technology. Field effect transistors [4] and ultra-sensitive nano-size gas sensors [5], nanoresonators and nanocantilevers [6] have also been fabricated based on individual nanobelts. Thermal transport along the nanobelt has also been measured. Nanocantilevers based on nanobelts have been fabricated. Very recently, structurally nanobelts exhibiting piezoelectric and ferroelectric properties have been synthesized, which could be a candidate for nano-scale traducers, actuators and sensors. [1] Z.W. Pan, Z.R. Dai and Z.L. Wang, Science, 209 (2001) 1947. [2] P. Poncharal, Z.L. Wang, D. Ugarte and W.A. de Heer, Science, 283 (1999) 1513; Electron Microscopy of Nanotubes, ed. Z.L. Wang and C. Hui, Kluwer Academic Publisher (2003). [3] R.P. Gao, Z.L. Wang, Z.G. Bai, W. de Heer

  9. Flow Energy Piezoelectric Bimorph Nozzle Harvester

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Lee, Hyeong Jae; Kim, Namhyo; Sun, Kai; Corbett, Gary; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffery L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro

    2014-01-01

    There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

  10. Flow energy piezoelectric bimorph nozzle harvester

    NASA Astrophysics Data System (ADS)

    Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffrey L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro; Kim, Namhyo; Sun, Kai; Corbett, Gary

    2014-04-01

    There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

  11. Ferromagnetic ZnO bicrystal nanobelts fabricated in low temperature

    SciTech Connect

    Xu Congkang; Chun, Junghwan; Rho, Keehan; Lee, Hyo Jin; Jeong, Yoon Hee; Kim, Dong-Eon; Chon, Bonghwan; Hong, Sangsu; Joo, Taiha

    2006-08-28

    Zinc oxide bicrystal nanobelts were fabricated via a vapor phase transport of a powder mixture of Zn, BiI{sub 3}, and MnCl{sub 2}{center_dot}H{sub 2}O at temperatures as low as 300 deg. C. The bicrystal nanobelts, growing along the [011{sup -}3] direction, have the widths of 40-150 nm and lengths of tens of microns. The energy dispersive x-ray spectroscopy result verifies that the bicrystal nanobelts contain higher concentration of both Bi and Mn along the grain boundary. The investigation of the growth mechanism proposes that MnBi may induce the formation of bicrystal nanobelts. Photoluminescence spectra show that the ultraviolet emission of the bicrystal nanobelts has a blueshift of 18 meV as compared to Bi-ZnO nanowires at 10 K. The bicrystal nanobelts also exhibit ferromagnetism at room temperature.

  12. NiMnGa/Si Shape Memory Bimorph Nanoactuation

    NASA Astrophysics Data System (ADS)

    Lambrecht, Franziska; Lay, Christian; Aseguinolaza, Iván R.; Chernenko, Volodymyr; Kohl, Manfred

    2016-12-01

    The size dependences of thermal bimorph and shape memory effect of nanoscale shape memory alloy (SMA)/Si bimorph actuators are investigated in situ in a scanning electron microscope and by finite element simulations. By combining silicon nanomachining and magnetron sputtering, freestanding NiMnGa/Si bimorph cantilever structures with film/substrate thickness of 200/250 nm and decreasing lateral dimensions are fabricated. Electrical resistance and mechanical beam bending tests upon direct Joule heating demonstrate martensitic phase transformation and reversible thermal bimorph effect, respectively. Corresponding characteristics are strongly affected by the large temperature gradient in the order of 50 K/µm forming along the nano bimorph cantilever upon electro-thermal actuation, which, in addition, depends on the size-dependent heat conductivity in the Si nano layer. Furthermore, the martensitic transformation temperatures show a size-dependent decrease by about 40 K for decreasing lateral dimensions down to 200 nm. The effects of heating temperature and stress distribution on the nanoactuation performance are analyzed by finite element simulations revealing thickness ratio of SMA/Si of 90/250 nm to achieve an optimum SME. Differential thermal expansion and thermo-elastic effects are discriminated by comparative measurements and simulations on Ni/Si bimorph reference actuators.

  13. Bimorph mirrors: The Good, the Bad, and the Ugly

    NASA Astrophysics Data System (ADS)

    Alcock, Simon G.; Sutter, John P.; Sawhney, Kawal J. S.; Hall, David R.; McAuley, Katherine; Sorensen, Thomas

    2013-05-01

    Bimorph mirrors are widely used by the X-ray, Laser, Space, and Astronomy communities to focus or collimate photon beams. Applying voltages to the embedded piezo ceramics enables the user to globally bend the optical substrate to a range of figures (including cylindrical, parabolic, and elliptical), and finely correct low spatial frequency errors, thus improving optical performance. Bimorph mirrors are employed on numerous synchrotron X-ray beamlines, including several at Diamond Light Source. However, many such beamlines were not achieving the desired size and shape of the reflected X-ray beam. Metrology data from ex-situ, slope measuring profilometry (using the Diamond-NOM) and in-situ, synchrotron X-ray "pencil-beam" scans, revealed sharp defects on the optical substrate directly above the locations at which the piezo ceramics are bonded together. This so-called "junction effect" has been observed on a variety of bimorph mirrors with different numbers of piezos, substrate length, and thickness. To repair this damage, three pairs of bimorph mirrors were re-polished at Thales-SESO. We review the re-polishing process, and show that it successfully removed the junction effect, and significantly improved beamline performance. Since the internal structure of the bimorph mirrors was not modified during re-polishing, it is hoped that the mirrors will retain their surface quality, and remain operational for many years. We also highlight the combination of super-polishing techniques with bimorph technology to create the "Ultimate" mirror, and discuss a next generation, bimorph mirror which is predicted not to suffer from the junction effect.

  14. Development of an innovative energy harvesting device using MFC bimorphs

    NASA Astrophysics Data System (ADS)

    Tabesh, Majid; Nguyen, The; Motlagh, Amin M.; Elahinia, Mohammad

    2009-03-01

    Recently, widespread attention has been directed towards scavenging energy from renewable sources such as wind. Piezoelectric materials are particularly suitable for capturing energy from motion since mechanical deflection of a piezoelectric specimen results in an electric displacement. This electricity can be stored in batteries or used to power portable devices. The present work is on the development of a device that can generate electricity from an oscillating motion using a piezoelectric Macro Fiber Composite (MFC) bimorph. Previously, bimorph vibration was created by a rotating or reciprocating part hitting the bimorph tip; whereas in the current work, base reciprocation excites the piezoelectric bimorph. The device includes a fan blade, which aligns with the direction of the wind and moves a rod in vertical direction. The microfiber composite beams (MFC) are attached to the upper end of the rod. Reciprocation of the rod acts as a harmonic excitation for the MFC bimorphs. Vibration of the MFCs produces electricity which is stored in a capacitor to be used to power electronic systems such as different types of remote sensors. Simulation and experimental results have been compared. In vibration and wind tunnel experiments, comparable amounts of energy were collected and accumulated in a capacitor.

  15. Laser cooling of CdS nanobelts: thickness matters.

    PubMed

    Li, Dehui; Zhang, Jun; Xiong, Qihua

    2013-08-12

    We report on the thickness dependent laser cooling in CdS nanobelts pumped by a 532 nm green laser. The lowest achievable cooling temperature is found to strongly depend on thickness. No net cooling can be achieved in nanobelts with a thickness below 65 nm due to nearly zero absorption and larger surface nonradiative recombination. While for nanobelts thicker than ~120 nm, the reabsorption effect leads to the reduction of the cooling temperature. Based on the thickness dependent photoconductivity gain, mean emission energy and external quantum efficiency, the modeling of the normalized temperature change suggests a good agreement with the experimental results.

  16. Integration of metal oxide nanobelts with microsystems for nerve agent detection

    NASA Astrophysics Data System (ADS)

    Yu, Choongho; Hao, Qing; Saha, Sanjoy; Shi, Li; Kong, Xiangyang; Wang, Z. L.

    2005-02-01

    We have assembled tin dioxide nanobelts with low-power microheaters for detecting dimethyl methylphosphonate (DMMP), a nerve agent simulant. The electrical conductance of a heated nanobelt increased for 5% upon exposure to 78 parts per billion DMMP in air. The nanobelt conductance recovered fully quickly after the DMMP was shut off, suggesting that the single-crystal nanobelt was not subject to poisoning often observed in polycrystalline metal oxide sensors. While the sensitivity can be improved via doping nanobelts with catalytic additives, directed assembly or growth of nanobelts on microsystems will potentially allow for the large-scale fabrication of nanosensor arrays.

  17. Novel high-bandwidth bimorph deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, Michael S.; Laycock, Leslie C.; Archer, Nick J.

    2004-12-01

    Adaptive Optics (AO) is a critical underpinning technology for future laser delivery (including free-space optical communications), target illumination and imaging systems. It measures and compensates for optical distortion caused by transmission through the atmosphere, resulting in the ability to deploy smaller lasers and identify targets at greater ranges. One of the key components in an AO system is the wavefront modifier, which acts on the incoming or outgoing beam to counter the effects of the atmosphere. BAE SYSTEMS Advanced Technology Centre is developing multi-element bimorph deformable mirrors for such an applications. Our initial designs were based on a standard construction and exhibited a resonant frequency of 1kHz with a maximum stroke of +/-20μm for an active aperture of 50mm. These devices were limited by the necessity to have a 'dead space' between the inner active area and the mirror boundary; this ensured that both the requirements for the stroke and the fixed boundary conditions could be met simultaneously. However, there was a significant penalty to pay in terms of bandwidth, which is inversely proportional to the square of the full mirror diameter. In a series of iteration steps, we have created novel mounting arrangements that reduce dead space and thus provide the optimum trade-off between bandwidth and stroke. These schemes include supporting the mirror from underneath, rather than at its edge. As a result, models of 60mm active diameter mirrors predict a resonance in excess of 5kHz, combined with a maximum stroke greater than +/-40μm. This paper will discuss a number of different mirror designs and present experimental results for recently assembled devices.

  18. Reactivity of gold nanobelts with unique {110} facets.

    PubMed

    Chen, Ying; Milenkovic, Srdjan; Hassel, Achim Walter

    2010-09-10

    Gold nanobelts were synthesized by directional solidification of the Fe-Au eutectoid followed by selective phase dissolution. Cleaning from organic molecules was performed in alkaline solution by PbO(2) deposition/dissolution to avoid surface reconstruction. The electrochemical behaviour of the Au nanobelts was determined by structure-sensitive electrochemical reactions, and the findings confirm the results obtained by selected area electron diffraction (SAED). The underpotential deposition (UPD) of lead under alkaline conditions and cyclic voltammograms (CVs) in sulphuric acid revealed an unusual large amount of (110) domains (>65%). Finally, after cleaning the Au nanobelts showed a higher and stable electrocatalytic behaviour toward methanol oxidation in alkaline media. The possible mechanism and the potential applications of the Au nanobelts are discussed.

  19. Optical Sensor Based on a Single CdS Nanobelt

    PubMed Central

    Li, Lei; Yang, Shuming; Han, Feng; Wang, Liangjun; Zhang, Xiaotong; Jiang, Zhuangde; Pan, Anlian

    2014-01-01

    In this paper, an optical sensor based on a cadmium sulfide (CdS) nanobelt has been developed. The CdS nanobelt was synthesized by the vapor phase transportation (VPT) method. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) results revealed that the nanobelt had a hexagonal wurtzite structure of CdS and presented good crystal quality. A single nanobelt Schottky contact optical sensor was fabricated by the electron beam lithography (EBL) technique, and the device current-voltage results showed back-to-back Schottky diode characteristics. The photosensitivity, dark current and the decay time of the sensor were 4 × 104, 31 ms and 0.2 pA, respectively. The high photosensitivity and the short decay time were because of the exponential dependence of photocurrent on the number of the surface charges and the configuration of the back to back Schottky junctions. PMID:24763211

  20. Optical sensor based on a single CdS nanobelt.

    PubMed

    Li, Lei; Yang, Shuming; Han, Feng; Wang, Liangjun; Zhang, Xiaotong; Jiang, Zhuangde; Pan, Anlian

    2014-04-23

    In this paper, an optical sensor based on a cadmium sulfide (CdS) nanobelt has been developed. The CdS nanobelt was synthesized by the vapor phase transportation (VPT) method. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) results revealed that the nanobelt had a hexagonal wurtzite structure of CdS and presented good crystal quality. A single nanobelt Schottky contact optical sensor was fabricated by the electron beam lithography (EBL) technique, and the device current-voltage results showed back-to-back Schottky diode characteristics. The photosensitivity, dark current and the decay time of the sensor were 4 × 10⁴, 31 ms and 0.2 pA, respectively. The high photosensitivity and the short decay time were because of the exponential dependence of photocurrent on the number of the surface charges and the configuration of the back to back Schottky junctions.

  1. Transport properties and nanosensors of oxide nanowires and nanobelts

    NASA Astrophysics Data System (ADS)

    Lao, Changshi

    ZnO is one of the most important materials for electronics, optoelectronics, piezoelectricity and optics. With a wide band gap of 3.37eV and an exiton binding energy of 60meV, ZnO ID nanostructures exhibit promising properties in a lot of optical device applications. It is also an important piezoelectric material and has applications in a new category of nanodevices, nano-piezotronics. Demonstrated prototype of devices includes nanogenerators, piezoelectric-FET, and a series of evolutive devices based on the concept of nanogenerator. This is based on working principle of a semiconductor and piezoelectric coupled property. This thesis is about the growth, characterization and device fabrication of ZnO nanowires and nanobelts for sensors and UV detectors. First, the fundamental synthesis of ZnO nanostructurs is investigated, particularly polar surface dominated nanostructues, to illustrate the unique growth configurations of ZnO nanobelts, nanorings and nanosprings. Detail study in this part includes nanobelts, nanorings, nanocombs, nanonetworks, and nanodiskettes synthesis. Important factors in driving the nanostructure synthesis mechanism are analyzed, such as the chemical activities of different surface of ZnO, the abundant of available Zn ions in the vapor, and the polar surface dominated effects. These factors contribute to the large abundant available ZnO nanostructures. Then, the devices fabricated methods using individual nanowires/nanobelts and their electrical transport properties were carefully characterized. In this part, dominant factors which are critical for nanobelt device performance are investigated, such as the contact properties, interface effects, and durability testing. Also, a metal doping method is studied to explore the controlling and modification of nanowire electric and optical properties. Research results obtained here provide a basic and thoroughly understanding the control process and fabrication criteria in building a functional

  2. New Interfacial Nanochemistry on Sensory Bioscaffold-Membranes of Nanobelts

    NASA Astrophysics Data System (ADS)

    Chen, Feng

    Nanostructured bioscaffolds and biosensors are evolving as popular and powerful tools in life science and biotechnology, due to the possible control of their surface and structural properties at the nm-scale. Being seldom discussed in literature and long-underexploited in materials and biomedical sciences, development of nanofiber-based sensory bioscaffolds has great promises and grand challenges in finding an ideal platform for low-cost quantifications of biological and chemical species in real-time, label-free, and ultrasensitive fashion. In this study, titanate nanobelts were first of all synthesized, from hydrothermal reactions of a NaOH (or KOH solution) with TiO2 powder, to possess underexploited structure and surface vital to the rapid and label-free electrochemical detections of protein (cytochrome c) and neurotransmitter (dopamine). This work is based on a suite of new physical and chemical properties on the titanate nanobelt in water, including high surface area, zwitterionic surface, chemical- and photochemical-durability, cation-exchange and anion- and cation-sorption capacities, protein- and cell-compatibility, thermal-stability, and charge conductivity. The Fourier transform infrared (FTIR) was used for identifying any denaturing of the cytochrome c pre-immobilized on the titanate nanobelts. On that basis, the pheochromocytoma cells (PC-12 cell) were chosen to grow on the titanate nanobelts. These experiments prove that the sensory bioscaffolds of titanate nanobelt-membrane is a multiplex platform for developing new tools for energy, environmental and life sciences.

  3. Electromechanical properties of nanotube-PVA composite actuator bimorphs.

    PubMed

    Bartholome, Christèle; Derré, Alain; Roubeau, Olivier; Zakri, Cécile; Poulin, Philippe

    2008-08-13

    Oxidized multiwalled carbon nanotube (oxidized-MWNT)/polyvinyl alcohol (PVA) composite sheets have been prepared for electromechanical actuator applications. MWNT have been oxidized by nitric acid treatments. They were then dispersed in water and mixed with various amounts of PVA of high molecular weight (198 000 g mol(-1)). The composite sheets were then obtained through a membrane filtration process. The composition of the systems has been optimized to combine suitable mechanical and electrical properties. Thermogravimetric analysis, mechanical tensile tests and conductivity measurements show that the best compromise of mechanical and electrical properties was obtained for a PVA weight fraction of about 30 wt%. In addition, one face of the sheets was coated with gold to increase the conductivity of the sheets and promote uniform actuation. Pseudo-bimorph devices have been realized by subsequently coating the composite sheets with an inert layer of PVA. The devices have been tested electromechanically in a liquid electrolyte (tetrabutylammonium/tetrafluoroborate (TBA/TFB) in acetonitrile) at constant frequency and different applied voltages, from 2 to 10 V. Measurements of the bimorph deflections were used to determine the stress generated by the nanotube-PVA sheets. The results show that the stress generated increases with increasing amplitude of the applied voltage and can reach 1.8 MPa. This value compares well with and even exceeds the stress generated by recently obtained bimorphs made of gold nanoparticles.

  4. Tailoring insoluble nanobelts into soluble anti-UV nanopotpourris

    NASA Astrophysics Data System (ADS)

    Wang, Jinmin; Sun, Xiao Wei; Jiao, Zhihui; Khoo, Eugene; Lee, Pooi See; Ma, Jan; Demir, Hilmi Volkan

    2011-11-01

    Soluble, transparent and anti-UV nanopotpourris have been prepared by tailoring long nanobelts. The strains and layered structures facilitate the breaking of the as-synthesized nanobelts under an applied mechanical action. The developed tailoring process of nanobelts is a general top-down secondary processing of layered nanostructures at the nanoscale level, which can be expended to the modifications of layered nanowires, nanotubes and hierarchical nanostructures. By tailoring, the size, morphology and solubility are modified, which may open up an area of advanced processing of nanomaterials and hint at some potential applications. Because of the excellent solubility of the tailored nanopotpourris, they are easily dispersed in cosmetics or polymer films, which are quite useful for some anti-UV protection applications, such as anti-UV sunscreen creams and anti-UV window films for vehicles and buildings.

  5. Novel hybrid materials based on the vanadium oxide nanobelts

    NASA Astrophysics Data System (ADS)

    Zabrodina, G. S.; Makarov, S. G.; Kremlev, K. V.; Yunin, P. A.; Gusev, S. A.; Kaverin, B. S.; Kaverina, L. B.; Ketkov, S. Yu.

    2016-04-01

    Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V2O5·nH2O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB - cetyltrimethylammonium bromide, TBAB - tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA)0.33V2O5 flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA)0.33V2O5, (TBA)0.16V2O5 nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

  6. Syntax-Directed Translations and Quasi-alphabetic Tree Bimorphisms — Revisited

    NASA Astrophysics Data System (ADS)

    Maletti, Andreas; Tîrnăucă, Cătălin Ionuţ

    Quasi-alphabetic tree bimorphisms [ Steinby, Tîrnă ucă: Defining syntax-directed translations by tree bimorphisms. Theor. Comput. Sci., to appear. http://dx.doi.org/10.1016/j.tcs.2009.03.009 , 2009] are reconsidered. It is known that the class of (string) translations defined by such bimorphisms coincides with the class of syntax-directed translations. This result is extended to a smaller class of tree bimorphisms namely (linear and complete) symbol-to-symbol tree bimorphisms. Moreover, it is shown that the class of simple syntax-directed translations coincides with the class of translations defined by alphabetic tree bimorphisms (also known as finite-state relabelings). This proves that alphabetic tree bimorphisms are not sufficiently powerful to model all syntax-directed translations. Finally, it is shown that the class of tree transformations defined by quasi-alphabetic tree bimorphisms is closed under composition. The corresponding result is known in the variable-free case. Overall, the main results of [ Steinby, Tîrnă ucă] are strengthened.

  7. Porous and single-crystalline ZnO nanobelts: fabrication with annealing precursor nanobelts, and gas-sensing and optoelectronic performance.

    PubMed

    Jin, Xiao-Bo; Li, Yi-Xiang; Su, Yao; Guo, Zheng; Gu, Cui-Ping; Huang, Jia-Rui; Meng, Fan-Li; Huang, Xing-Jiu; Li, Min-Qiang; Liu, Jin-Huai

    2016-09-02

    Porous and single-crystalline ZnO nanobelts have been prepared through annealing precursors of ZnSe · 0.5N2H4 well-defined and smooth nanobelts, which have been synthesized via a simple hydrothermal method. The composition and morphology evolutions with the calcination temperatures have been investigated in detail for as-prepared precursor nanobelts, suggesting that they can be easily transformed into ZnO nanobelts by preserving their initial morphology via calcination in air. In contrast, the obtained ZnO nanobelts are densely porous, owing to the thermal decomposition and oxidization of the precursor nanobelts. More importantly, the achieved porous ZnO nanobelts are single-crystalline, different from previously reported ones. Motivated by the intrinsic properties of the porous structure and good electronic transporting ability of single crystals, their gas-sensing performance has been further explored. It is demonstrated that porous ZnO single-crystalline nanobelts exhibit high response and repeatability toward volatile organic compounds, such as ethanol and acetone, with a short response/recovery time. Furthermore, their optoelectronic behaviors indicate that they can be promisingly employed to fabricate photoelectrochemical sensors.

  8. Porous and single-crystalline ZnO nanobelts: fabrication with annealing precursor nanobelts, and gas-sensing and optoelectronic performance

    NASA Astrophysics Data System (ADS)

    Jin, Xiao-Bo; Li, Yi-Xiang; Su, Yao; Guo, Zheng; Gu, Cui-Ping; Huang, Jia-Rui; Meng, Fan-Li; Huang, Xing-Jiu; Li, Min-Qiang; Liu, Jin-Huai

    2016-09-01

    Porous and single-crystalline ZnO nanobelts have been prepared through annealing precursors of ZnSe · 0.5N2H4 well-defined and smooth nanobelts, which have been synthesized via a simple hydrothermal method. The composition and morphology evolutions with the calcination temperatures have been investigated in detail for as-prepared precursor nanobelts, suggesting that they can be easily transformed into ZnO nanobelts by preserving their initial morphology via calcination in air. In contrast, the obtained ZnO nanobelts are densely porous, owing to the thermal decomposition and oxidization of the precursor nanobelts. More importantly, the achieved porous ZnO nanobelts are single-crystalline, different from previously reported ones. Motivated by the intrinsic properties of the porous structure and good electronic transporting ability of single crystals, their gas-sensing performance has been further explored. It is demonstrated that porous ZnO single-crystalline nanobelts exhibit high response and repeatability toward volatile organic compounds, such as ethanol and acetone, with a short response/recovery time. Furthermore, their optoelectronic behaviors indicate that they can be promisingly employed to fabricate photoelectrochemical sensors.

  9. Piezoelectric Bimorph Cantilever for Vibration-Producing-Hydrogen

    PubMed Central

    Zhang, Jun; Wu, Zheng; Jia, Yanmin; Kan, Junwu; Cheng, Guangming

    2013-01-01

    A device composed of a piezoelectric bimorph cantilever and a water electrolysis device was fabricated to realize piezoelectrochemical hydrogen production. The obvious output of the hydrogen and oxygen through application of a mechanical vibration of ∼0.07 N and ∼46.2 Hz was observed. This method provides a cost-effective, recyclable, environment-friendly and simple way to directly split water for hydrogen fuels by scavenging mechanical waste energy forms such as noise or traffic vibration in the environment. PMID:23271601

  10. Bimorph mirrors for adaptive optics in space telescopes

    NASA Astrophysics Data System (ADS)

    Alaluf, D.; Bastaits, R.; Wang, K.; Horodinca, M.; Burda, I.; Martic, G.; Preumont, A.

    2016-07-01

    This paper discusses a concept of bimorph deformable mirror used in adaptive optics to compensate for manufacturing errors, gravity release and thermal distortion affecting large lightweight mirrors in space telescopes. The mirror consists of a single-crystal Silicon wafer (D=75 mm t=500μm) covered with an optical coating on the front side and an array of 25 independent PZT actuators acting in d31 mode on the back side. The mirror is mounted on an isostatic support with three linear PZT actuators controlling the rigid-body motion. The paper presents the experimental results obtained with this design and a new, more compact alternative.

  11. Suspended microfluidics.

    PubMed

    Casavant, Benjamin P; Berthier, Erwin; Theberge, Ashleigh B; Berthier, Jean; Montanez-Sauri, Sara I; Bischel, Lauren L; Brakke, Kenneth; Hedman, Curtis J; Bushman, Wade; Keller, Nancy P; Beebe, David J

    2013-06-18

    Although the field of microfluidics has made significant progress in bringing new tools to address biological questions, the accessibility and adoption of microfluidics within the life sciences are still limited. Open microfluidic systems have the potential to lower the barriers to adoption, but the absence of robust design rules has hindered their use. Here, we present an open microfluidic platform, suspended microfluidics, that uses surface tension to fill and maintain a fluid in microscale structures devoid of a ceiling and floor. We developed a simple and ubiquitous model predicting fluid flow in suspended microfluidic systems and show that it encompasses many known capillary phenomena. Suspended microfluidics was used to create arrays of collagen membranes, mico Dots (μDots), in a horizontal plane separating two fluidic chambers, demonstrating a transwell platform able to discern collective or individual cellular invasion. Further, we demonstrated that μDots can also be used as a simple multiplexed 3D cellular growth platform. Using the μDot array, we probed the combined effects of soluble factors and matrix components, finding that laminin mitigates the growth suppression properties of the matrix metalloproteinase inhibitor GM6001. Based on the same fluidic principles, we created a suspended microfluidic metabolite extraction platform using a multilayer biphasic system that leverages the accessibility of open microchannels to retrieve steroids and other metabolites readily from cell culture. Suspended microfluidics brings the high degree of fluidic control and unique functionality of closed microfluidics into the highly accessible and robust platform of open microfluidics.

  12. Large-scale growth of millimeter-long single-crystalline ZnS nanobelts

    SciTech Connect

    Li Jianye Zhang Qi; An Lei; Qin Luchang; Liu Jie

    2008-11-15

    Millimeter-long single-crystalline hexagonal ZnS nanobelts were grown on specific locations on a wafer scale. This is the first time that the millimeter-scale ZnS nanobelt has been synthesized. The longest nanobelts are about 3 mm. The as-grown nanobelts were characterized by means of field emission scanning electron microscopy, X-ray powder diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction. The results indicate that the ultra-long nanobelts are pure single-crystalline hexagonal ZnS. There are two kinds of ZnS nanobelts existing in the products. One is the nanobelts that have two smooth sides and grow along the [0 0 1] longitudinal direction, and the other is the nanobelts that have one smooth side and one saw-teeth-like side, namely nanosaws, and grow along the [2 1 0] longitudinal direction. A vapor-liquid-solid mechanism is suggested for the lengthwise growth of the ZnS nanobelts (nanosaws) and a vapor-solid mechanism for the side direction growth of the saw-teeth of the nanosaws. - Graphical Abstract: Millimeter-long single-crystalline ZnS nanobelts were grown on specific locations on a large scale. There are two kinds of nanobelts in the products-one has two smooth sides, and the other has one smooth side and one saw-teeth-like side, namely nanosaws. Mechanisms for the longitudinal direction growth of the nanobelts/nanosaws and the side saw-teeth direction growth of the nanosaws are discussed.

  13. Viability study of oscillatory flow pumps using bimorph piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Vatanabe, Sandro L.; Pires, Rogério F.; Choi, Andres; Nakasone, Paulo H.; Silva, Emílio C. N.

    2007-04-01

    Precision flow pumps have been widely studied over the last three decades. They have been applied in the areas of Biology, Pharmacy and Medicine in applications usually related to the dosage of medicine and chemical reagents. In addition, thermal management solutions for electronic devices have also been recently developed using these kinds of pumps offering better performance with low noise and low power consumption. In a previous work, the working principle of a pump based on the use of a bimorph piezoelectric actuator inserted in a fluid channel to generate flow was presented. In this work, a novel configuration of this piezoelectric flow pump that consists of a flow pump using two bimorph piezoelectric actuators in parallel configuration has been studied and it is presented. This configuration was inspired on fish swimming modes. The complete cycle of pump development was conducted, consisting in designing, manufacturing, and experimental characterization steps. Load-loss and flow rate characterization experimental tests were conducted, generating data that allows us to analyze the influence of geometric parameters in the pump performance. Comparisons among numerical and experimental results were made to validate the computational results and improve the accuracy of the implemented models.

  14. New configurations of oscillatory flow pumps using bimorph piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Vatanabe, Sandro L.; Pires, Rogério F.; Nakasone, Paulo H.; Silva, Emílio C. N.

    2008-03-01

    Precision flow pumps have been widely studied over the last three decades. They have been applied in the areas of Biology, Pharmacy and Medicine in applications usually related to the dosage of medicine and chemical reagents. In addition, thermal management solutions for electronic devices have also been recently developed using these kinds of pumps offering better performance with low noise and low power consumption. In previous works was presented the working principle of a pump based on the use of a bimorph piezoelectric actuator inserted in a fluid channel to generate flow. This work presents a novel configuration of piezoelectric flow pumps using a bimorph piezoelectric actuator of different aspect ratio. Sensibility studies of the rectangular cross-sectional area channel are conducted computationally (CFD) and three parameters are investigated: resonance frequency and oscillation amplitude of the piezoelectric actuator, and pressure inside the channel. Also, experimental tests are conducted to verify the influence of clamps' rigidity and actuator's insulator. The experimental results show that improving these two aspects it is possible to achieve higher flow rates.

  15. Temperature effect on electrospinning of nanobelts: the case of hafnium oxide

    NASA Astrophysics Data System (ADS)

    Su, Yurong; Lu, Bingan; Xie, Yizhu; Ma, Ziwei; Liu, Lixin; Zhao, Haiting; Zhang, Jia; Duan, Huigao; Zhang, Hongliang; Li, Jian; Xiong, Yuqing; Xie, Erqing

    2011-07-01

    Electrospinning is a convenient and versatile method for fabricating different kinds of one-dimensional nanostructures such as nanofibres, nanotubes and nanobelts. Environmental parameters have a great influence on the electrospinning nanostructure. Here we report a new method to fabricate hafnium oxide (HfO2) nanobelts. HfO2 nanobelts were prepared by electrospinning a sol-gel solution with the implementation of heating and subsequent calcination treatment. We investigate the temperature dependence of the products by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and energy-dispersive x-ray (EDX) spectroscopy. The heating temperature of spinning ambient is found to be crucial to the formation of HfO2 nanobelts. By tuning the temperature, the morphological transformation of HfO2 from nanowires to nanobelts was achieved. It was found that the rapid evaporation of solvent played an important role in the formation process of HfO2 nanobelts. It is shown that nanobelts can only be obtained with the temperature higher than 50 °C and they are in the high quality monoclinic phase. A possible growth mechanism of the nanobelts based on phase separation is proposed. The enhanced photoluminescence (PL) of HfO2:Eu3 + nanobelts is also illustrated.

  16. Controllable synthesis of ultrathin vanadium oxide nanobelts via an EDTA-mediated hydrothermal process

    NASA Astrophysics Data System (ADS)

    Yu-Xiang, Qin; Cheng, Liu; Wei-Wei, Xie; Meng-Yang, Cui

    2016-02-01

    Ultrathin VO2 nanobelts with rough alignment features are prepared on the induction layer-coated substrates by an ethylenediaminetetraacetic acid (EDTA)-mediated hydrothermal process. EDTA acts as a chelating reagent and capping agent to facilitate the one-dimensional (1D) preferential growth of ultrathin VO2 nanobelts with high crystallinities and good uniformities. The annealed induction layer and concentration of EDTA are found to play crucial roles in the formation of aligned and ultrathin nanobelts. Variation in EDTA concentration can change the VO2 morphology of ultrathin nanobelts into that of thick nanoplates. Mild annealing of ultrathin VO2 nanobelts at 350 °C in air results in the formation of V2O5 nanobelts with a nearly unchanged ultrathin structure. The nucleation and growth mechanism involved in the formations of nanobelts and nanoplates are proposed. The ethanol gas sensing properties of the V2O5 nanobelt networks-based sensor are investigated in a temperature range from 100 °C to 300 °C over ethanol concentrations ranging from 3 ppm to 500 ppm. The results indicate that the V2O5 nanobelt network sensor exhibits high sensitivity, good reversibility, and fast response-recovery characteristics with an optimal working temperature of 250 °C. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274074, 61271070, and 61574100).

  17. Noble metal nanoparticle-decorated TiO2 nanobelts for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    He, Haiyan; Yang, Ping; Jia, Changchao; Miao, Yanping; Zhao, Jie; Du, Yingying

    2014-07-01

    TiO2 nanobelts have been fabricated through a hydrothermal method and subsequently sulfuric-acid-corrosion-treated for a rough surface. Noble metal nanoparticles such as Ag and Au were deposited on the coarse surface of TiO2 nanobelts via a coprecipitation procedure. Ag-TiO2 nanobelts were prepared in ethanolic solution contained silver nitrate (AgNO3) and sodium hydroxide (NaOH). Au-TiO2 nanobelts were obtained in chloroauric acid (HAuCl4) using sodium borohydride (NaBH4) as the reductant. It is confirmed by the results of XRD patterns together with the SEM images that the composite of noble metal and TiO2 nanobelts were obtained successfully and the Ag or Au nanoparticles were well-dispersed on the TiO2 nanobelts. Moreover, the as-prepared Ag and Au nanoparticle-decorated TiO2 nanobelts represent an enhanced photocatalytic activity compared with pure TiO2 nanobelts, which is due to the fact that the Ag and Au nanoparticles on the surface of TiO2 nanobelts act as sinks for the photogenerated electrons and promote the separation of the electrons and holes.

  18. Y-shaped ZnO Nanobelts Driven from Twinned Dislocations

    NASA Astrophysics Data System (ADS)

    Shi, Yuan; Bao, Shuhan; Shi, Run; Huang, Chengzi; Amini, Abbas; Wu, Zefei; Zhang, Linfei; Wang, Ning; Cheng, Chun

    2016-03-01

    Y-shaped ZnO nanobelts are fabricated by a simple thermal evaporation method. Transmission Electron Microscopy (TEM) investigation shows that these ZnO nanobelts are crystals with twinned planes {11–21}. Convergent Beam Electron Diffraction studies show that the two sides of twinned nanobelts are O-terminated towards the twinned boundary and Zn-terminated outwards. The two branches of twinned ZnO nanobelts grow along [11–26] from the trunk and then turn to the polarization direction [0001]. The featured Y-shape morphology and TEM characterizations indicate that the growth of these novel nanostructures is driven by an unusual twinned dislocation growth mechanism.

  19. Enhanced Magnetoelectric Coupling in Layered Structure of Piezoelectric Bimorph and Metallic Alloy

    NASA Astrophysics Data System (ADS)

    Petrov, V. M.; Bichurin, M. I.; Lavrentyeva, K. V.; Leontiev, V. S.

    2016-08-01

    We have investigated the enhanced magnetoelectric (ME) coupling in a layered structure of piezoelectric bimorph and magnetostrictive metallic alloy. The observed ME coefficient in the piezoelectric bimorph-based structure was found to be two times higher than in the traditional piezoelectric/magnetostrictive bilayer. The observed enhancement in ME coupling strength is related to equal signs of induced voltage in both lead zirconate titanate layers with opposite poling directions due to the flexural deformations. The piezoelectric bimorph-based structure has promising potential for sensor and technological applications.

  20. An exceptional bimorph effect and a low quality factor from carbon nanotube-polymer composites.

    PubMed

    Hsu, Wen-Kuang; Chu, Huai-Yuan; Chen, Ting-Hsien; Cheng, Tung-Wen; Fang, Weileun

    2008-04-02

    Microcantilever actuators made from carbon nanotube polymer are driven at very low pull-in voltages and the thermal bimorph effect reaches 325 microm at 26-110 degrees C, much greater than the values for existing devices.

  1. Flapping Wing Technology for Micro Air Vehicles Incorporating a Lead Zirconate Titanate (PZT) Bimorph Actuator

    DTIC Science & Technology

    2012-06-01

    Flapping Wing Technology for Micro Air Vehicles Incorporating a Lead Zirconate Titanate (PZT) Bimorph Actuator by Asha J. Hall, Richard A...Laboratory Aberdeen Proving Ground, MD 21005 ARL-TR-6040 June 2012 Flapping Wing Technology for Micro Air Vehicles Incorporating a Lead Zirconate ...2011 to April 2012 4. TITLE AND SUBTITLE Flapping Wing Technology for Micro Air Vehicles Incorporating a Lead Zirconate Titanate (PZT) Bimorph

  2. Taming excitons in II-VI semiconductor nanowires and nanobelts

    NASA Astrophysics Data System (ADS)

    Xu, Xinlong; Zhang, Qing; Zhang, Jun; Zhou, Yixuan; Xiong, Qihua

    2014-10-01

    Excitons are one of the most important fundamental quasi-particles, and are involved in a variety of processes forming the basis of a wide range of opto-electronic and photonic devices based on II-VI semiconductor nanowires and nanobelts, such as light-emitting diodes, photovoltaic cells, photodetectors and nanolasers. A clear understanding of their properties and unveiling the potential engineering for excitons is of particular importance for the design and optimization of nanoscale opto-electronic and photonic devices. Herein, we present a comprehensive review on discussing the fundamental behaviours of the excitons in one-dimensional (1D) II-VI semiconductor nanomaterials (nanowires and nanobelts). We will start with a focus on the unique properties (origin, generation, etc) and dynamics of excitons and exciton complexes in the II-VI semiconductor nanowires and nanobelts. Then we move to the recent progress on the excitonic response in 1D nanomaterials and focus on the tailoring and engineering of excitonic properties through rational controlling of the physical parameters and conditions, intrinsically and extrinsically. These include (1) exciton-exciton interaction, which is important for 1D nanomaterial nanolasing; (2) exciton-phonon interaction, which has interesting applications for laser cooling; and (3) exciton-plasmon interaction, which is the cornerstone towards the realization of plasmonic lasers. The potential of electric field, morphology and size control for excitonic properties is also discussed. Unveiling and controlling excitonic properties in II-VI semiconductor nanowires and nanobelts would promote the development of 1D nanoscience and nanotechnology.

  3. Characterization of polymer films for use in bimorph chemical sensors

    NASA Astrophysics Data System (ADS)

    Chatzandroulis, S.; Goustouridis, D.; Raptis, I.

    2005-01-01

    In the present work white light interferometry is applied for the characterization of polymer films commonly used in bimorph chemical sensors. The study focuses on methacrylate polymers with positive tone patterning capabilities. The behavior upon exposure to controlled concentrations volatile organic compound and water vapors of thin poly (hydroxy ethyl methacrylate) (PHEMA) and poly (methyl methacrylate) (PMMA) layers was evaluated. The normalized film expansion for PHEMA, compared to PMMA, is higher in the case of water and methanol vapors, almost equal for ethanol and significantly lower in the case of acetone. This behavior could be attributed to the combination of polarity and hydrogen bonding capability of the analytes. A wide polymer film thickness range was examined and it was revealed that the normalized film expansion in both PHEMA and PMMA is nearly constant for films thicker than 100 nm and increases for thinner films.

  4. Degradation of bimorph piezoelectric bending beams in energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Pillatsch, P.; Xiao, B. L.; Shashoua, N.; Gramling, H. M.; Yeatman, E. M.; Wright, P. K.

    2017-03-01

    Piezoelectric energy harvesting is an attractive alternative to battery powering for wireless sensor networks. However, in order for it to be a viable long term solution the fatigue life needs to be assessed. Many vibration harvesting devices employ bimorph piezoelectric bending beams as transduction elements to convert mechanical to electrical energy. This paper introduces two degradation studies performed under symmetrical and asymmetrical sinusoidal loading. It is shown that besides a loss in output power, the most dramatic effect of degradation is a shift in resonance frequency which is highly detrimental to resonant harvester designs. In addition, micro-cracking was shown to occur predominantly in piezoelectric layers under tensile stress. This opens the opportunity for increased life time through compressive operation or pre-loading of piezoceramic layers.

  5. Cantilevered bimorph-based scanner for high speed atomic force microscopy with large scanning range.

    PubMed

    Zhou, Yusheng; Shang, Guangyi; Cai, Wei; Yao, Jun-en

    2010-05-01

    A cantilevered bimorph-based resonance-mode scanner for high speed atomic force microscope (AFM) imaging is presented. The free end of the bimorph is used for mounting a sample stage and the other one of that is fixed on the top of a conventional single tube scanner. High speed scanning is realized with the bimorph-based scanner vibrating at resonant frequency driven by a sine wave voltage applied to one piezolayer of the bimorph, while slow scanning is performed by the tube scanner. The other piezolayer provides information on vibration amplitude and phase of the bimorph itself simultaneously, which is used for real-time data processing and image calibration. By adjusting the free length of the bimorph, the line scan rate can be preset ranging from several hundred hertz to several kilohertz, which would be beneficial for the observation of samples with different properties. Combined with a home-made AFM system and a commercially available data acquisition card, AFM images of various samples have been obtained, and as an example, images of the silicon grating taken at a line rate of 1.5 kHz with the scan size of 20 microm are given. By manually moving the sample of polished Al foil surface while scanning, the capability of dynamic imaging is demonstrated.

  6. Sb2O3 nanobelt networks for excellent visible-light-range photodetectors

    NASA Astrophysics Data System (ADS)

    Li, L.; Zhang, Y. X.; Fang, X. S.; Zhai, T. Y.; Liao, M. Y.; Wang, H. Q.; Li, G. H.; Koide, Y.; Bando, Y.; Golberg, D.

    2011-04-01

    Excellent photoconductive properties have been found in Sb2O3 nanobelts synthesized by a surfactant-assisted solvothermal method. Visible-light photodetectors have been designed from Sb2O3 nanobelt networks using micrometer-wide gold wires as masks. Photodetectors show high sensitivity to visible light, high stability, and reproducibility. Fast response and decay times (<0.3 s) are comparable or even better than these parameters in many other metal oxide nanoscale photodetectors. The dominant mechanism of excellent photoconductivity is attributed to the barrier height modulations in the nanobelt-to-nanobelt contact regions. These results demonstrate that Sb2O3 nanobelt networks can indeed serve as high-performance photodetectors in the visible light range.

  7. Enhanced photocatalytic performance of porous TiO2 nanobelts with phase junctions

    NASA Astrophysics Data System (ADS)

    Pang, Lai-xue; Wang, Xiao-ying; Tang, Xin-de

    2015-01-01

    Porous TiO2 nanobelts with rutile/anatase phase junctions are successfully prepared through a hydrothermal route and ion exchange process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were conducted to characterize the products. The photocatalytic performance of the porous nanobelts was evaluated by measuring the degradation of methyl blue under UV light irradiation. The photocatalytic activity of the porous nanobelts is much superior to that of P-25 and pristine non-porous nanobelts. The excellent photocatalytic of porous nanobelts can be attributed to pores which enhanced ability in UV-light harvesting. What's more, the existence of rutile/anatase phase junction is favorable for the formation and separation of the hole-electron pair, resulting in a reduced electron-hole recombination.

  8. Characterization of a next-generation piezo bimorph X-ray mirror for synchrotron beamlines

    PubMed Central

    Alcock, Simon G.; Nistea, Ioana; Sutter, John P.; Sawhney, Kawal; Fermé, Jean-Jacques; Thellièr, Christophe; Peverini, Luca

    2015-01-01

    Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the ‘junction effect’: a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate. In order to address this problem, a next-generation bimorph with piezos bonded to the side faces of a monolithic substrate was developed at Thales-SESO and optimized at Diamond Light Source. Using metrology feedback from the Diamond-NOM, the optical slope error was reduced to ∼0.5 µrad r.m.s. for a range of ellipses. To maximize usability, a novel holder was built to accommodate the substrate in any orientation. When replacing a first-generation bimorph on a synchrotron beamline, the new mirror significantly improved the size and shape of the reflected X-ray beam. Most importantly, there was no evidence of the junction effect even after eight months of continuous beamline usage. It is hoped that this new design will reinvigorate the use of active bimorph optics at synchrotron and free-electron laser facilities to manipulate and correct X-ray wavefronts. PMID:25537582

  9. Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

    PubMed Central

    Cathcart, Nicole; Kitaev, Vladimir

    2016-01-01

    A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design. PMID:27605125

  10. Characterization of a next-generation piezo bimorph X-ray mirror for synchrotron beamlines.

    PubMed

    Alcock, Simon G; Nistea, Ioana; Sutter, John P; Sawhney, Kawal; Fermé, Jean Jacques; Thellièr, Christophe; Peverini, Luca

    2015-01-01

    Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the `junction effect': a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate. In order to address this problem, a next-generation bimorph with piezos bonded to the side faces of a monolithic substrate was developed at Thales-SESO and optimized at Diamond Light Source. Using metrology feedback from the Diamond-NOM, the optical slope error was reduced to ∼ 0.5 µrad r.m.s. for a range of ellipses. To maximize usability, a novel holder was built to accommodate the substrate in any orientation. When replacing a first-generation bimorph on a synchrotron beamline, the new mirror significantly improved the size and shape of the reflected X-ray beam. Most importantly, there was no evidence of the junction effect even after eight months of continuous beamline usage. It is hoped that this new design will reinvigorate the use of active bimorph optics at synchrotron and free-electron laser facilities to manipulate and correct X-ray wavefronts.

  11. Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

    NASA Astrophysics Data System (ADS)

    Cathcart, Nicole; Kitaev, Vladimir

    2016-09-01

    A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.

  12. Piezoelectric Bimorphs' Characteristics as In-Socket Sensors for Transfemoral Amputees

    PubMed Central

    El-Sayed, Amr M.; Hamzaid, Nur Azah; Osman, Noor Azuan Abu

    2014-01-01

    Alternative sensory systems for the development of prosthetic knees are being increasingly highlighted nowadays, due to the rapid advancements in the field of lower limb prosthetics. This study presents the use of piezoelectric bimorphs as in-socket sensors for transfemoral amputees. An Instron machine was used in the calibration procedure and the corresponding output data were further analyzed to determine the static and dynamic characteristics of the piezoelectric bimorph. The piezoelectric bimorph showed appropriate static operating range, repeatability, hysteresis, and frequency response for application in lower prosthesis, with a force range of 0–100 N. To further validate this finding, an experiment was conducted with a single transfemoral amputee subject to measure the stump/socket pressure using the piezoelectric bimorph embedded inside the socket. The results showed that a maximum interface pressure of about 27 kPa occurred at the anterior proximal site compared to the anterior distal and posterior sites, consistent with values published in other studies. This paper highlighted the capacity of piezoelectric bimorphs to perform as in-socket sensors for transfemoral amputees. However, further experiments are recommended to be conducted with different amputees with different socket types. PMID:25513823

  13. Piezoelectric bimorphs' characteristics as in-socket sensors for transfemoral amputees.

    PubMed

    El-Sayed, Amr M; Hamzaid, Nur Azah; Abu Osman, Noor Azuan

    2014-12-10

    Alternative sensory systems for the development of prosthetic knees are being increasingly highlighted nowadays, due to the rapid advancements in the field of lower limb prosthetics. This study presents the use of piezoelectric bimorphs as in-socket sensors for transfemoral amputees. An Instron machine was used in the calibration procedure and the corresponding output data were further analyzed to determine the static and dynamic characteristics of the piezoelectric bimorph. The piezoelectric bimorph showed appropriate static operating range, repeatability, hysteresis, and frequency response for application in lower prosthesis, with a force range of 0-100 N. To further validate this finding, an experiment was conducted with a single transfemoral amputee subject to measure the stump/socket pressure using the piezoelectric bimorph embedded inside the socket. The results showed that a maximum interface pressure of about 27 kPa occurred at the anterior proximal site compared to the anterior distal and posterior sites, consistent with values published in other studies. This paper highlighted the capacity of piezoelectric bimorphs to perform as in-socket sensors for transfemoral amputees. However, further experiments are recommended to be conducted with different amputees with different socket types.

  14. Flexible Heteroepitaxy of CoFe2O4/Muscovite Bimorph with Large Magnetostriction.

    PubMed

    Liu, Heng-Jui; Wang, Chih-Kuo; Su, Dong; Amrillah, Tahta; Hsieh, Ying-Hui; Wu, Kun-Hong; Chen, Yi-Chun; Juang, Jenh-Yih; Eng, Lukas M; Jen, Shien-Uang; Chu, Ying-Hao

    2017-03-01

    A bimorph composed of ferrimagnetic cobalt ferrite (CoFe2O4, CFO) and flexible muscovite was fabricated via van der Waals epitaxy. The combination of X-ray diffraction and transmission electron microscopy was conducted to reveal the heteroepitaxy of the CFO/muscovite system. The robust magnetic behaviors against mechanical bending were characterized by hysteresis measurements and magnetic force microscopy, which maintain a saturation magnetization (Ms) of ∼120-150 emu/cm(3) under different bending states. The large magnetostrictive response of the CFO film was then determined by digital holographic microscopy, where the difference of magnetostrction coefficient (Δλ) is -104 ppm. The superior performance of this bimorph is attributed to the nature of weak interaction between film and substrate. Such a flexible CFO/muscovite bimorph provides a new platform to develop next-generation flexible magnetic devices.

  15. Flexible Heteroepitaxy of CoFe 2 O 4 /Muscovite Bimorph with Large Magnetostriction

    DOE PAGES

    Liu, Heng-Jui; Wang, Chih-Kuo; Su, Dong; ...

    2017-02-03

    Van der Waals epitaxy was used to fabricate a bimorph composed of ferrimagnetic cobalt ferrite (CoFe2O4, CFO) and flexible muscovite. The combination of X-ray diffraction and transmission electron microscopy was conducted to reveal the heteroepitaxy of the CFO/muscovite system. The robust magnetic behaviors against mechanical bending were characterized by hysteresis measurements and magnetic force microscopy, which maintain a saturation magnetization (Ms) of ~120–150 emu/cm3 under different bending states. The large magnetostrictive response of the CFO film was then determined by digital holographic microscopy, where the difference of magnetostrction coefficient (Δλ) is -104 ppm. We attribute the superior performance of thismore » bimorph to the nature of weak interaction between film and substrate. Such a flexible CFO/muscovite bimorph provides a new platform to develop next-generation flexible magnetic devices.« less

  16. Surface depletion induced quantum confinement in CdS nanobelts.

    PubMed

    Li, Dehui; Zhang, Jun; Xiong, Qihua

    2012-06-26

    We investigate the surface depletion induced quantum confinement in CdS nanobelts beyond the quantum confinement regime, where the thickness is much larger than the bulk exciton Bohr radius. From room temperature to 77 K, the emission energy of free exciton A scales linearly versus 1/L(2) when the thickness L is less than 100 nm, while a deviation occurs for those belts thicker than 100 nm due to the reabsorption effect. The 1/L(2) dependence can be explained by the surface depletion induced quantum confinement, which modifies the confinement potential leading to a quasi-square potential well smaller than the geometric thickness of nanobelts, giving rise to the confinement effect to exciton emission beyond the quantum confinement regime. The surface depletion is sensitive to carrier concentration and surface states. As the temperature decreases, the decrease of the electrostatic potential drop in the surface depletion region leads to a weaker confinement due to the decrease of carrier concentration. With a layer of polymethyl methacrylate (PMMA) passivation, PL spectra exhibit pronounced red shifts due to the decrease of the surface states at room temperature. No shift is found at 10 K both with or without PMMA passivation, suggesting a much weaker depletion field due to the freezing-out of donors.

  17. Growth and low-temperature photoluminescence properties of hybrid ZnO-SnO2 nanobelts

    NASA Astrophysics Data System (ADS)

    Sinha, S. K.; Rakshit, T.; Ray, S. K.; Bysakh, S.; Manna, I.

    2012-09-01

    Hybrid ZnO-SnO2 nanobelts were synthesized through a simple thermal evaporation technique without using any catalyst. Detailed microstructural investigation showed that the nanobelts possessed doped/alloyed wurtzite (ZnO) and rutile (SnO2) structures. The diameter and length of the nanobelts were in the ranges 100-200 and 20-40 µm, respectively. Low-temperature photoluminescence properties of the hybrid ZnO-SnO2 nanostructured aggregate revealed a red shift of near-band-edge emission peaks of ZnO with increasing temperature. The method of synthesis offers a convenient and effective technique of producing hybrid ZnO-SnO2 nanobelts for gas sensing in the large quantity.

  18. Investigation of photoelectrical properties of α-Si3N4 nanobelts with surface modifications using first-principles calculations.

    PubMed

    Xiong, Li; Dai, Jianhong; Song, Yan; Wen, Guangwu; Qin, Chunlin

    2016-06-21

    The structural stability, electronic and optical properties of α-Si3N4 nanobelts orientating along the different directions with surface H, F and Cl modifications are investigated using first-principles methods. The stabilities of α-Si3N4 nanobelts are greatly affected by the surface modifications and increased in the order of H, Cl and F. All the modified α-Si3N4 nanobelts exhibit semiconductor characteristics. The effective masses of nanobelts are mainly affected by their orientations as well as surface modifications. The band gaps of α-Si3N4 nanobelts are found to be modulated by surface modifications. The Cl-modified nanobelts result in a smaller band gap than that of H- or F-modified ones. The electronic properties of α-Si3N4 nanobelts have significantly affected their optical properties. The linear light response ranges are mainly located in the ultraviolet region, where the absorption and refraction of light mainly occur, while the reflection is very weak. As the halogen coverage increases to 100%, the absorption edges of α-Si3N4 nanobelts have an obvious red-shift and new dielectric peaks appear. The Cl-modified nanobelts possess higher ε2(ω) peaks, lower absorption edges and better photoelectric characteristics than those of H- or F-modified nanobelts. The static optical parameters ε(0) and n(0) of 100% Cl-modified α-Si3N4 nanobelts are significantly larger than those of other nanobelts, indicating special applications in certain optical components.

  19. Crystal-phase control of molybdenum carbide nanobelts for dehydrogenation of benzyl alcohol.

    PubMed

    Li, Zhongcheng; Chen, Chunhui; Zhan, Ensheng; Ta, Na; Li, Yong; Shen, Wenjie

    2014-05-04

    Belt-shaped molybdenum carbides in α- and β-phases were synthesized by reducing and carburizing a nano-sized α-MoO3 precursor with hydrocarbon-hydrogen mixtures at appropriate temperatures; the β-Mo2C nanobelts with a higher fraction of coordinatively unsaturated Mo sites were more active than the α-MoC1-x nanobelts in dehydrogenation of benzyl alcohol to benzaldehyde.

  20. Hexagonal NiS nanobelts as advanced cathode materials for rechargeable Al-ion batteries.

    PubMed

    Yu, Zhijing; Kang, Zepeng; Hu, Zongqian; Lu, Jianhong; Zhou, Zhigang; Jiao, Shuqiang

    2016-08-16

    Hexagonal NiS nanobelts served as novel cathode materials for rechargeable Al-ion batteries based on an AlCl3/[EMIm]Cl ionic liquid electrolyte system. The nano-banded structure of the materials can facilitate the electrolyte immersion and enhance Al(3+) diffusion. The hexagonal NiS nanobelt based cathodes exhibit high storage capacity, good cyclability and low overpotential.

  1. Synthesis of CaCO3 Nanobelts for Drug Delivery in Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Sun, Dongmei; Peng, Haibao; Wang, Shilong; Zhu, Dazhang

    2015-05-01

    Nanobelt carriers have demonstrated some advantages such as good biocompatibility, biodegradability, and strain-accommodating properties. We prepared an optimized nanobelt carrier formulation for drug (etoposide) as an oral delivery system and estimated the potential of calcium carbonate (CaCO3) nanobelts. The nanobelts were prepared by the method of binary solvent approach and were characterized by transmission electron microscope (TEM), scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) spectra. MTT (3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide) assay test exhibited that etoposide-loaded calcium carbonate nanobelts (ECCNBs) showed a higher cell kill ratio against SGC-7901 cells compared with free drug. The apoptosis test and cell cycle test analysis revealed that etoposide entrapped in calcium carbonate nanobelts (CCNBs) could enhance the delivery efficiencies of drug and improved inhibition effect. The present findings demonstrated that ECCNBs might induce cell cycle arrest at G2/M phase and cell apoptosis in a p53-related manner. It can be foreseen that CCNBs are a promising drug carrier to store the anti-cancer drug for cancer therapy and drug delivery.

  2. Centimeter-long Ta3N5 nanobelts: synthesis, electrical transport, and photoconductive properties

    NASA Astrophysics Data System (ADS)

    Wu, X. C.; Tao, Y. R.; Li, L.; Bando, Y.; Golberg, D.

    2013-05-01

    Centimeter-long Ta3N5 nanobelts were synthesized by a reaction of centimeter-long TaS3 nanobelt templates with flowing NH3 at 800 °C for 2 h. The nanobelts have cross-sections of about 50 × 100 nm2, and lengths up to 0.5 cm. A field effect transistor (FET) made of a single Ta3N5 nanobelt was fabricated on silica/silicon substrate. The electric transport of the individual nanobelt revealed that the nanobelt is a semiconductor with a room-temperature resistivity of 11.88 Ω m, and can be fitted well with an empirical formula ρ = 10831 exp(-T/43.8) - 22.6, where ρ is resistivity (Ω m) and T is absolute temperature (K). The FET showed decent photoconductive performance under light irradiation in the range 250-630 nm. The photocurrent increased by nearly 10 times the dark current under 450 nm light irradiation at an applied voltage of 5.0 V.

  3. Orientation- and passivation-dependent stability and electronic properties of α-Si3N4 nanobelts.

    PubMed

    Xiong, Li; Dai, Jianhong; Zhong, Bo; Wen, Guangwu; Song, Yan

    2014-11-28

    The energetic stability and electronic properties of unpassivated, hydrogen (-H) and hydroxyl (-OH) passivated α-Si3N4 nanobelts orientating along the [101], [210], [011], [100], [001], and [110] directions are investigated by first-principles calculations. Calculations show that the energetic stabilities of α-Si3N4 nanobelts depend weakly upon orientations of nanobelts, but sensitively on passivation treatments. The most stable nanobelt is the OH cluster partially passivated α-Si3N4, followed by the H atom fully passivated and the unpassivated systems. All the unpassivated nanobelts show metallic characteristics due to the presence of dangling bonds of surficial atoms in nanobelts, while all the passivated nanobelts exhibit semiconducting characteristics. The valence band maximum (VBM) and the conduction band minimum (CBM) mainly originate from the surface N-2p and Si-3p states, respectively. For α-Si3N4 nanobelts orientating along [101], [210], [011] and [110] directions, the OH passivated systems exhibit a much smaller band gap than the H passivated systems, while the [100] and [001] orientated nanobelts exhibit the opposite band-gap properties.

  4. A versatile MEMS bimorph actuator with large vertical displacement and high resolution: Design and fabrication process

    NASA Astrophysics Data System (ADS)

    Rangra, Aarushee; Maninder, K.; Soni, Shilpi; Rangra, K. J.

    2016-04-01

    This paper presents design, simulation results and envisaged fabrication process for a versatile MEMS bimorph actuator with large out of plane displacement and high resolution. A comparative study of mechanical, thermal and electrical response of the micro-actuator is presented by using two well-known MEMS simulation tools. The bimorph structure measuring 700 × 1280 mm2 is fully integrable with CMOS fabrication process. It is indented for tunable filter applications where the precise vertical motion of the payload, the top metallic electrode anchored rigidly to bimorph `springs' spans the vertical range of 250-300 microns with submicron resolution. Each bimorph spring resembles a hair pin structure and is composed of materials with large difference in thermal expansion coefficients e.g. electroplated gold and polysilicon for optimal out-of-the plane deflection. The novel structure can also be configured for analog micro-mirror based optical and IR spectroscopy applications by controlling the actuation bias and top electrode surface parameters.

  5. Structural and optical properties of hydrothermally synthesized vanadium oxides nanobelts

    NASA Astrophysics Data System (ADS)

    Derkaoui, I.; Khenfouch, M.; Elmokri, I.; Mothudi, B. M.; Dhlamini, M. S.; Moloi, S. J.; Zorkani, I.; Jorio, A.; Maaza, M.

    2017-03-01

    Nanostructured metal oxides have attracted a lot of attention recently owning to their unique structural advantages, and demonstrated promising chemical and physical properties for various applications. In this study, we report the structural and optical properties of vanadium oxide nanoparticles (VO-NPs) prepared via a hydrothermal method. Our results are revealing that the components of VO-NPs films are having a belt-like shape with a uniform size distribution. The nanobelts with very smooth and flat surfaces have a typical length of up to 1μm and a width of about 9-14 nm. Moreover, The UV-Visible spectroscopy revealed an excellent optical propertiesshowing clearly the good stoichiometry and crystallinity of our VO-NPs films. This synthesis method provides a new simple route to fabricate one-dimensional nanostructured metal oxides which is suitable for a large field of applications.

  6. Synthesis and characterization of α-cobalt hydroxide nanobelts

    NASA Astrophysics Data System (ADS)

    Tian, L.; Zhu, J. L.; Chen, L.; An, B.; Liu, Q. Q.; Huang, K. L.

    2011-08-01

    α-Cobalt hydroxide was synthesized by a facile hydrothermal process from Co(Ac)2 and NH3·H2O in the presence of 1,3-propanediol. The large-scale-prepared cobalt hydroxide has a uniform nanobelt morphology with a considerably high aspect-ratio more than 20 which may be advantageous for exploration of their physicochemical properties. This synthetic method is convenient, economical, and controllable. The samples were characterized by powder X-ray diffraction, energy dispersive spectrum, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, CHN element analysis, thermogravimetric and differential-thermogravimetric analysis, which revealed the compound is lamellar structural cobalt organic-inorganic hybrid with the chemical formula of Co(OH)1.49(NH3)0.01(CO3 2-)0.22(Ac-)0.07(H2O)0.11 and single-crystalline.

  7. A finger-like hardness tester based on the contact electromechanical impedance of a piezoelectric bimorph cantilever.

    PubMed

    Fu, Ji; Li, Faxin

    2015-10-01

    We proposed a finger-like hardness tester based on the electromechanical impedance of a piezoelectric bimorph cantilever. A Vickers indenter was fabricated to the free end of the bimorph to contact the sample. The contact force was monitored by a strain gauge and the contact area was obtained by tracking the bimorph's resonance frequency. The bimorph-sample contact system was modeled by the electromechanical equivalent circuit method. Verification experiments on standard hardness samples were conducted and the measured hardness values agreed well with those given by a conventional Vickers hardness tester. Further hardness measurement on a gear wheel showed that the proposed hardness tester is very adaptive and can be used for inner surface testing or in situ testing, where other hardness testers may not be applicable. The proposed hardness tester can be regarded as an improved ultrasonic hardness tester.

  8. One-dimensional copper hydroxide nitrate nanorods and nanobelts for radiochemical applications.

    PubMed

    Liu, Bin

    2012-11-21

    I report a facile wet-chemical method for the synthesis of one-dimensional copper hydroxide nitrate nanostructures in 2-propanol under solvothermal conditions. Single-crystalline nearly monodispersed copper hydroxide nitrate nanorods and nanobelts with selected breadths in the range of 100 nm to 1 μm have been successfully prepared by a solvothermal method through controlling the experimental parameters, including initial concentrations of reagents, reaction temperature, solvent and reaction time. The resultant nanorods and nanobelts were characterized using FESEM, TEM, XRD, FTIR and TGA techniques. Upon thermal calcination, the copper hydroxide nitrate nanorods and nanobelts self-assemble into one-dimensional arrays (rods, belts or tubes) of copper oxide nanoparticles. The as-prepared copper hydroxide nitrate nanorods and nanobelts were tested as ion exchangers for removal of long-lived radioactive anions such as (129)I(-) and (99)TcO(4)(-). The copper hydroxide nitrate nanorods or nanobelts were over two times more active in the removal of anion species than copper hydroxide nitrate nanoplatelets.

  9. Enhanced photocatalytic performances of CeO2/TiO2 nanobelt heterostructures.

    PubMed

    Tian, Jian; Sang, Yuanhua; Zhao, Zhenhuan; Zhou, Weijia; Wang, Dongzhou; Kang, Xueliang; Liu, Hong; Wang, Jiyang; Chen, Shaowei; Cai, Huaqiang; Huang, Hui

    2013-11-25

    CeO2 /TiO2 nanobelt heterostructures are synthesized via a cost-effective hydrothermal method. The as-prepared nanocomposites consist of CeO2 nanoparticles assembled on the rough surface of TiO2 nanobelts. In comparison with P25 TiO2 colloids, surface-coarsened TiO2 nanobelts, and CeO2 nanoparticles, the CeO2 /TiO2 nanobelt heterostructures exhibit a markedly enhanced photocatalytic activity in the degradation of organic pollutants such as methyl orange (MO) under either UV or visible light irradiation. The enhanced photocatalytic performance is attributed to a novel capture-photodegradation-release mechanism. During the photocatalytic process, MO molecules are captured by CeO2 nanoparticles, degraded by photogenerated free radicals, and then released to the solution. With its high degradation efficiency, broad active light wavelength, and good stability, the CeO2 /TiO2 nanobelt heterostructures represent a new effective photocatalyst that is low-cost, recyclable, and will have wide application in photodegradation of various organic pollutants. The new capture-photodegradation-release mechanism for improved photocatalysis properties is of importance in the rational design and synthesis of new photocatalysts.

  10. The Sensing Properties of Single Y-Doped SnO2 Nanobelt Device to Acetone.

    PubMed

    Li, Xinmin; Liu, Yingkai; Li, Shuanghui; Huang, Jieqing; Wu, Yuemei; Yu, Dapeng

    2016-12-01

    Pure SnO2 and Y-doped SnO2 nanobelts were prepared by thermal evaporation at 1350 °C in the presence of Ar carrier gas (30 sccm). The samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersion spectrometer (EDS), X-ray photoelectron spectrometer (XPS), UV-Vis absorption spectroscopy, Raman spectroscopy, and Fourier transform infrared spectrum (FTIR). The sensing properties of the devices based on a single SnO2 nanobelt and Y-doped SnO2 nanobelt were explored to acetone, ethanol, and ethanediol. It reveals that the sensitivity of single Y-doped SnO2 nanobelt device is 11.4 to 100 ppm of acetone at 210 °C, which is the highest response among the three tested VOC gases. Y(3+) ions improve the sensitivity of SnO2 sensor and have an influence on the optical properties of Y-doped SnO2 nanobelts.

  11. Modeling of the Through-the-Thickness Electric Potentials of a Piezoelectric Bimorph Using the Spectral Element Method

    PubMed Central

    Dong, Xingjian; Peng, Zhike; Hua, Hongxing; Meng, Guang

    2014-01-01

    An efficient spectral element (SE) with electric potential degrees of freedom (DOF) is proposed to investigate the static electromechanical responses of a piezoelectric bimorph for its actuator and sensor functions. A sublayer model based on the piecewise linear approximation for the electric potential is used to describe the nonlinear distribution of electric potential through the thickness of the piezoelectric layers. An equivalent single layer (ESL) model based on first-order shear deformation theory (FSDT) is used to describe the displacement field. The Legendre orthogonal polynomials of order 5 are used in the element interpolation functions. The validity and the capability of the present SE model for investigation of global and local responses of the piezoelectric bimorph are confirmed by comparing the present solutions with those obtained from coupled 3-D finite element (FE) analysis. It is shown that, without introducing any higher-order electric potential assumptions, the current method can accurately describe the distribution of the electric potential across the thickness even for a rather thick bimorph. It is revealed that the effect of electric potential is significant when the bimorph is used as sensor while the effect is insignificant when the bimorph is used as actuator, and therefore, the present study may provide a better understanding of the nonlinear induced electric potential for bimorph sensor and actuator. PMID:24561399

  12. Size-tunable Synthesis of Silver Nanobelts Using a Polyaniline Derived Polymer as a Template

    NASA Astrophysics Data System (ADS)

    Padmanaban, Sudakar; Kim, Minog; Yoon, Sungho

    2017-03-01

    Silver nanobelts (AgNBs) have attracted a great interest due to their excellent electrical conductivity and mechanical strength, leading a facile synthesis of these AgNBs in great demand. In here, we are reporting a simple, aqueous phase, size tunable synthesis of smooth surfaced 1D-silver nanobelts using a Polyaniline (PANi) derived polymer at room temperature. The specifically designed PANi polymer, comprising a pendant carboxyl group in the chain, acted as both a reducing agent and template. The resulting Ag nanobelts have more than 10 μm of length, mean width values ranging from 41.1 (11.5) nm to 118.5 (8.8) nm and a mean thickness value of 36.7 (12.5) nm. The UV-Visible spectrum of the AgNBs has shown two Surface Plasmon Resonance peaks at 352 nm and 383 nm.

  13. Size-tunable Synthesis of Silver Nanobelts Using a Polyaniline Derived Polymer as a Template

    PubMed Central

    Padmanaban, Sudakar; Kim, Minog; Yoon, Sungho

    2017-01-01

    Silver nanobelts (AgNBs) have attracted a great interest due to their excellent electrical conductivity and mechanical strength, leading a facile synthesis of these AgNBs in great demand. In here, we are reporting a simple, aqueous phase, size tunable synthesis of smooth surfaced 1D-silver nanobelts using a Polyaniline (PANi) derived polymer at room temperature. The specifically designed PANi polymer, comprising a pendant carboxyl group in the chain, acted as both a reducing agent and template. The resulting Ag nanobelts have more than 10 μm of length, mean width values ranging from 41.1 (11.5) nm to 118.5 (8.8) nm and a mean thickness value of 36.7 (12.5) nm. The UV-Visible spectrum of the AgNBs has shown two Surface Plasmon Resonance peaks at 352 nm and 383 nm. PMID:28317940

  14. Deep-ultraviolet solar-blind photoconductivity of individual gallium oxide nanobelts

    NASA Astrophysics Data System (ADS)

    Li, Liang; Auer, Erwin; Liao, Meiyong; Fang, Xiaosheng; Zhai, Tianyou; Gautam, Ujjal K.; Lugstein, Alois; Koide, Yasuo; Bando, Yoshio; Golberg, Dmitri

    2011-03-01

    We designed solar-blind deep-ultraviolet semiconductor photodetectors using individual Ga2O3 nanobelts. The photoconductive behavior was systematically studied. The photodetectors demonstrate high selectivity towards 250 nm light, fast response times of less than 0.3 s, and a large photocurrent to dark current ratio of up to 4 orders of magnitude. The photoresponse parameters such as photocurrent, response time, and quantum efficiency depend strongly on the intensity of light, the detector environment, and the nanobelt size. The photoresponse mechanism was discussed, which was mainly attributed to the band bending, surface traps, and distribution of traps in the bandgap. Present Ga2O3 nanobelts can be exploited for future applications in photo sensing, light-emitting diodes, and optical switches.

  15. A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts

    NASA Astrophysics Data System (ADS)

    Alaferdov, A. V.; Savu, R.; Rackauskas, T. A.; Rackauskas, S.; Canesqui, M. A.; de Lara, D. S.; Setti, G. O.; Joanni, E.; de Trindade, G. M.; Lima, U. B.; de Souza, A. S.; Moshkalev, S. A.

    2016-09-01

    A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ˜103) graphite nanobelt thin films deposited by a modified Langmuir-Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain-release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.

  16. A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts.

    PubMed

    Alaferdov, A V; Savu, R; Rackauskas, T A; Rackauskas, S; Canesqui, M A; de Lara, D S; Setti, G O; Joanni, E; de Trindade, G M; Lima, U B; de Souza, A S; Moshkalev, S A

    2016-09-16

    A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ∼10(3)) graphite nanobelt thin films deposited by a modified Langmuir-Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain-release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.

  17. Adaptive optics vision simulation and perceptual learning system based on a 35-element bimorph deformable mirror.

    PubMed

    Dai, Yun; Zhao, Lina; Xiao, Fei; Zhao, Haoxin; Bao, Hua; Zhou, Hong; Zhou, Yifeng; Zhang, Yudong

    2015-02-10

    An adaptive optics visual simulation combined with a perceptual learning (PL) system based on a 35-element bimorph deformable mirror (DM) was established. The larger stroke and smaller size of the bimorph DM made the system have larger aberration correction or superposition ability and be more compact. By simply modifying the control matrix or the reference matrix, select correction or superposition of aberrations was realized in real time similar to a conventional adaptive optics closed-loop correction. PL function was first integrated in addition to conventional adaptive optics visual simulation. PL training undertaken with high-order aberrations correction obviously improved the visual function of adult anisometropic amblyopia. The preliminary application of high-order aberrations correction with PL training on amblyopia treatment was being validated with a large scale population, which might have great potential in amblyopia treatment and visual performance maintenance.

  18. Synthesis and characterization of α-MoO{sub 3} nanobelt composite positive electrode materials for lithium battery application

    SciTech Connect

    Nadimicherla, Reddeppa; Chen, Wen; Guo, Xin

    2015-06-15

    Graphical abstract: (a) TEM image of MoO{sub 3}/PEO nanobelts composite, (b) CV curves of MoO{sub 3}/PEO nanobelts composite. - Highlights: • α-MoO{sub 3} and PEO surfactant MoO{sub 3} nanobelts were synthesized by solvothermal method. • The capacity retention of 12.5 wt% PEO surfactant MoO{sub 3} nanobelts is 88.78%. • The specific capacity of 12.5 wt% PEO surfactant MoO{sub 3} nanobelts is 352 mAh g{sup −1}. • MoO{sub 3}/PEO nanobelts composite material demonstrates good cycling stability as cathode. - Abstract: α-MoO{sub 3} and PEO surfactant MoO{sub 3} nanobelts were synthesized by a solvothermal method. The morphology and nanostructure of samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bare α-MoO{sub 3} and 12.5 wt% PEO surfactant MoO{sub 3} nanobelts have an initial specific capacities of 279 and 352 mAh g{sup −1}, respectively, at constant current density 30 mA g{sup −1} with potential range of 1.5–4.0 V vs. Li/Li{sup +}. While MoO{sub 3} is modified by the intercalation of PEO, it is effectively shielded against electrostatic interaction between the MoO{sub 3} interlayer and Li{sup +} ions. We reported positive material, a nanocomposite of MoO{sub 3} coated with polyethylene oxide. It presents good cycling stability due to existence of the conductive and protective polyethylene oxide coating and the nanobelt morphology of MoO{sub 3}. The polyethylene oxide acts as a conducting matrix, a binder and an active material, as well as a volume change buffer agent, which holds the MoO{sub 3} particles in place during the discharge cycles. The cyclic voltammograms of the 12.5 wt% PEO surfactant MoO{sub 3} nanobelt composite displayed better cyclic performance compared with pure MoO{sub 3} nanobelts. The specific capacity of the pure MoO{sub 3} nanobelts and 12.5 wt% PEO surfactant MoO{sub 3

  19. An experimentally validated bimorph cantilever model for piezoelectric energy harvesting from base excitations

    NASA Astrophysics Data System (ADS)

    Erturk, A.; Inman, D. J.

    2009-02-01

    Piezoelectric transduction has received great attention for vibration-to-electric energy conversion over the last five years. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure, to generate electrical energy from base excitations. Several authors have investigated modeling of cantilevered piezoelectric energy harvesters under base excitation. The existing mathematical modeling approaches range from elementary single-degree-of-freedom models to approximate distributed parameter solutions in the sense of Rayleigh-Ritz discretization as well as analytical solution attempts with certain simplifications. Recently, the authors have presented the closed-form analytical solution for a unimorph cantilever under base excitation based on the Euler-Bernoulli beam assumptions. In this paper, the analytical solution is applied to bimorph cantilever configurations with series and parallel connections of piezoceramic layers. The base excitation is assumed to be translation in the transverse direction with a superimposed small rotation. The closed-form steady state response expressions are obtained for harmonic excitations at arbitrary frequencies, which are then reduced to simple but accurate single-mode expressions for modal excitations. The electromechanical frequency response functions (FRFs) that relate the voltage output and vibration response to translational and rotational base accelerations are identified from the multi-mode and single-mode solutions. Experimental validation of the single-mode coupled voltage output and vibration response expressions is presented for a bimorph cantilever with a tip mass. It is observed that the closed-form single-mode FRFs obtained from the analytical solution can successfully predict the coupled system dynamics for a wide range of electrical load resistance. The performance of the bimorph device is analyzed extensively for the short circuit and open circuit resonance

  20. Design of a Compact, Bimorph Deformable Mirror-Based Adaptive Optics Scanning Laser Ophthalmoscope.

    PubMed

    He, Yi; Deng, Guohua; Wei, Ling; Li, Xiqi; Yang, Jinsheng; Shi, Guohua; Zhang, Yudong

    2016-01-01

    We have designed, constructed and tested an adaptive optics scanning laser ophthalmoscope (AOSLO) using a bimorph mirror. The simulated AOSLO system achieves diffraction-limited criterion through all the raster scanning fields (6.4 mm pupil, 3° × 3° on pupil). The bimorph mirror-based AOSLO corrected ocular aberrations in model eyes to less than 0.1 μm RMS wavefront error with a closed-loop bandwidth of a few Hz. Facilitated with a bimorph mirror at a stroke of ±15 μm with 35 elements and an aperture of 20 mm, the new AOSLO system has a size only half that of the first-generation AOSLO system. The significant increase in stroke allows for large ocular aberrations such as defocus in the range of ±600° and astigmatism in the range of ±200°, thereby fully exploiting the AO correcting capabilities for diseased human eyes in the future.

  1. Analytical and experimental comparisons of electromechanical vibration response of a piezoelectric bimorph beam for power harvesting

    NASA Astrophysics Data System (ADS)

    Lumentut, M. F.; Howard, I. M.

    2013-03-01

    Power harvesters that extract energy from vibrating systems via piezoelectric transduction show strong potential for powering smart wireless sensor devices in applications of health condition monitoring of rotating machinery and structures. This paper presents an analytical method for modelling an electromechanical piezoelectric bimorph beam with tip mass under two input base transverse and longitudinal excitations. The Euler-Bernoulli beam equations were used to model the piezoelectric bimorph beam. The polarity-electric field of the piezoelectric element is excited by the strain field caused by base input excitation, resulting in electrical charge. The governing electromechanical dynamic equations were derived analytically using the weak form of the Hamiltonian principle to obtain the constitutive equations. Three constitutive electromechanical dynamic equations based on independent coefficients of virtual displacement vectors were formulated and then further modelled using the normalised Ritz eigenfunction series. The electromechanical formulations include both the series and parallel connections of the piezoelectric bimorph. The multi-mode frequency response functions (FRFs) under varying electrical load resistance were formulated using Laplace transformation for the multi-input mechanical vibrations to provide the multi-output dynamic displacement, velocity, voltage, current and power. The experimental and theoretical validations reduced for the single mode system were shown to provide reasonable predictions. The model results from polar base excitation for off-axis input motions were validated with experimental results showing the change to the electrical power frequency response amplitude as a function of excitation angle, with relevance for practical implementation.

  2. Ag nanoparticle mediated growth of CdS nanobelts

    NASA Astrophysics Data System (ADS)

    Sreejith, K.; Nuwad, J.; Thinaharan, C.; Dey, G. K.; Pillai, C. G. S.

    2007-06-01

    Catalytic growth of CdS have been carried out on large scale by evaporation of bulk CdS on Ag deposited Si (1 1 1) at atmospheric pressure. The as prepared CdS had wurtzite structure as evidenced by X-ray diffraction. The nanostructures were beltlike with several tens of micrometers length, several micrometers width and few nanometers to tens of nanometers thick as seen by scanning electron microscope and confirmed by TEM studies. The nanobelts were single crystalline in nature and showed reflection corresponding to (1 1 2) and (0 0 2) planes in SAED. The PL studies revealed the green band due to band gap emission and red band due to emission from the surface states. The higher intensity of the defect emission indicated the presence of considerable concentration of surface defects in the as prepared sample. The deposition of CdS could be explained on the basis of catalyst assisted vapor-liquid-solid and vapor-solid mechanism.

  3. Gas dependent sensing mechanism in ZnO nanobelt sensor

    NASA Astrophysics Data System (ADS)

    Kaur, Manmeet; Kailasaganapathi, S.; Ramgir, Niranjan; Datta, Niyanta; Kumar, Sushil; Debnath, A. K.; Aswal, D. K.; Gupta, S. K.

    2017-02-01

    Gas sensing properties of ZnO nanobelts synthesized using carbothermal reduction method has been investigated. At room temperature (28 °C), the sensor films exhibit an appreciable response towards H2S and NO and response of these two gases were studied as a function of concentration. For NO the sensor films exhibit a complete reversible curve for the concentration range between 1 and 60 ppm. However, for H2S a complete recovery was obtained for concentration <5 ppm and for higher concentration a partial recovery of the baseline resistance was observed. The reason for the incomplete recovery was investigated using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies of the sample before and after the H2S exposure. After exposure, appearance of an additional peak at 26.6° corresponding to the formation of ZnS was observed in XRD. Formation of additional phase was further corroborated using the results of XPS. H2S exposure causes decrease in the intensity of O 1s peak and appearance of sulphide peaks at binding energies of 162.8 and 161.8 eV corresponding to S-2p peaks - 2p3/2 and 2p1/2, confirms the formation of ZnS upon exposure.

  4. Structure and resistivity of bismuth nanobelts in situ synthesized on silicon wafer through an ethanol-thermal method

    SciTech Connect

    Gao Zheng; Qin Haiming; Yan Tao

    2011-12-15

    Bismuth nanobelts in situ grown on a silicon wafer were synthesized through an ethanol-thermal method without any capping agent. The structure of the bismuth belt-silicon composite nanostructure was characterized by scanning electron microscope, energy-dispersive X-ray spectroscopy, and high resolution transmission electron microscope. The nanobelt is a multilayered structure 100-800 nm in width and over 50 {mu}m in length. One layer has a thickness of about 50 nm. A unique sword-like nanostructure is observed as the initial structure of the nanobelts. From these observations, a possible growth mechanism of the nanobelt is proposed. Current-voltage property measurements indicate that the resistivity of the nanobelts is slightly larger than that of the bulk bismuth material. - Graphical Abstract: TEM images, EDS, and electron diffraction pattern of bismuth nanobelts. Highlights: Black-Right-Pointing-Pointer Bismuth nanobelts in situ grown on silicon wafer were achieved. Black-Right-Pointing-Pointer Special bismuth-silicon nanostructure. Black-Right-Pointing-Pointer Potential application in sensitive magnetic sensor and other electronic devices.

  5. Visible photocatalytic and photoelectrochemical activities of TiO2 nanobelts modified by In2O3 nanoparticles.

    PubMed

    Yang, Hongru; Tian, Jian; Bo, Yanyan; Zhou, Yanli; Wang, Xinzhen; Cui, Hongzhi

    2017-02-01

    Novel In2O3 nanoparticle/TiO2 nanobelt heterostructures with enhanced visible-light photocatalytic and photoelectrochemical (PEC) performance were successfully prepared via a facile hydrothermal method. Well-dispersed In2O3 nanoparticles with small sizes are uniformly attached on the surface of TiO2 nanobelts to form In2O3 nanoparticle/TiO2 nanobelt heterostructures. The TiO2 nanobelts as backbones restrict the aggregation of In2O3 nanoparticles, resulting in the formation of smaller In2O3 nanoparticles with more interaction sites for pollutants. The visible photocatalytic activity of as-prepared heterostructures for degradation of methyl blue (MB) is higher than those of TiO2 nanobelts and In2O3 nanoparticles alone. Moreover, the In2O3 nanoparticle/TiO2 nanobelt heterostructure shows an enhanced PEC performance under irradiation of visible light. The enhanced photocatalytic and PEC activities are mainly ascribed to the synergic effect of efficient charge separation of heterostructure, visible-light harvesting ability of In2O3, and the formation of preferential adsorption sites by the small size of In2O3 nanoparticles. Finally, based on the experimental results of Mott-Schottky, UV-vis DRS, photocurrent and open-circuit voltage response, a possible photocatalytic mechanism over the In2O3 nanoparticle/TiO2 nanobelt heterostructure is proposed.

  6. X-ray beam expansion by the application of re-entrant surface profiles to deformable bimorph mirrors

    NASA Astrophysics Data System (ADS)

    Sutter, John P.; Alcock, Simon G.; Kashyap, Yogesh; Nistea, Ioana; Wang, Hongchang; Sawhney, Kawal

    2016-09-01

    Deformable, piezo bimorph mirrors are often used to expand X-ray beams to a continuous range of sizes. However, optical polishing errors present on all X-ray mirrors introduce striations into the reflected beam. To counteract them, reentrant surface modifications with alternating concave and convex curvature have been proposed and applied to mirrors of fixed shape or bimorph mirrors. For the latter, a new method of constructing re-entrant surface modifications on segments of unequal length is described. This allows the re-entrant modification required for a desired beam size at the focal point to be matched to the bimorph mirror's polishing errors, thus reducing the voltage variations. Optical profilometry using the Diamond-NOM showed that a 5-segment and a 7-segment modification could be suitably applied to a deformable bimorph mirror. X-ray tests showed that striations caused by the 5-segment modification in the beam at the focus are concentrated at the beam edges, while the beam center is left clear. This is in contrast to simple defocusing, in which a strong side shoulder appears. The 7-segment modification produces a pattern of evenly spaced striations. The intensity spikes seen with the re-entrant modifications are caused chiefly by the finite curvature of the mirror at the turning points. The question of whether deformable bimorph mirrors with different piezo response functions could sharpen the curvature changes will be investigated. Optimal modifications of continuous curvature, which could more realistically be applied, will be sought.

  7. Energy scavenging based on a single-crystal PMN-PT nanobelt

    NASA Astrophysics Data System (ADS)

    Wu, Fan; Cai, Wei; Yeh, Yao-Wen; Xu, Shiyou; Yao, Nan

    2016-03-01

    Self-powered nanodevices scavenging mechanical energy require piezoelectric nanostructures with high piezoelectric coefficients. Here we report the fabrication of a single-crystal (1 ‑ x)Pb(Mg1/3Nb2/3)O3 ‑ xPbTiO3 (PMN-PT) nanobelt with a superior piezoelectric constant (d33 = ~550 pm/V), which is approximately ~150%, 430%, and 2100% of the largest reported values for previous PMN-PT, PZT and ZnO nanostructures, respectively. The high d33 of the single-crystalline PMN-PT nanobelt results from the precise orientation control during its fabrication. As a demonstration of its application in energy scavenging, a piezoelectric nanogenerator (PNG) is built on the single PMN-PT nanobelt, generating a maximum output voltage of ~1.2 V. This value is ~4 times higher than that of a single-CdTe PNG, ~13 times higher than that of a single-ZnSnO3 PNG, and ~26 times higher than that of a single-ZnO PNG. The profoundly increased output voltage of a lateral PNG built on a single PMN-PT nanobelt demonstrates the potential application of PMN-PT nanostructures in energy harvesting, thus enriching the material choices for PNGs.

  8. Energy scavenging based on a single-crystal PMN-PT nanobelt

    PubMed Central

    Wu, Fan; Cai, Wei; Yeh, Yao-Wen; Xu, Shiyou; Yao, Nan

    2016-01-01

    Self-powered nanodevices scavenging mechanical energy require piezoelectric nanostructures with high piezoelectric coefficients. Here we report the fabrication of a single-crystal (1 − x)Pb(Mg1/3Nb2/3)O3 − xPbTiO3 (PMN-PT) nanobelt with a superior piezoelectric constant (d33 = ~550 pm/V), which is approximately ~150%, 430%, and 2100% of the largest reported values for previous PMN-PT, PZT and ZnO nanostructures, respectively. The high d33 of the single-crystalline PMN-PT nanobelt results from the precise orientation control during its fabrication. As a demonstration of its application in energy scavenging, a piezoelectric nanogenerator (PNG) is built on the single PMN-PT nanobelt, generating a maximum output voltage of ~1.2 V. This value is ~4 times higher than that of a single-CdTe PNG, ~13 times higher than that of a single-ZnSnO3 PNG, and ~26 times higher than that of a single-ZnO PNG. The profoundly increased output voltage of a lateral PNG built on a single PMN-PT nanobelt demonstrates the potential application of PMN-PT nanostructures in energy harvesting, thus enriching the material choices for PNGs. PMID:26928788

  9. Energy scavenging based on a single-crystal PMN-PT nanobelt.

    PubMed

    Wu, Fan; Cai, Wei; Yeh, Yao-Wen; Xu, Shiyou; Yao, Nan

    2016-03-01

    Self-powered nanodevices scavenging mechanical energy require piezoelectric nanostructures with high piezoelectric coefficients. Here we report the fabrication of a single-crystal (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (PMN-PT) nanobelt with a superior piezoelectric constant (d33 = ~550 pm/V), which is approximately ~150%, 430%, and 2100% of the largest reported values for previous PMN-PT, PZT and ZnO nanostructures, respectively. The high d33 of the single-crystalline PMN-PT nanobelt results from the precise orientation control during its fabrication. As a demonstration of its application in energy scavenging, a piezoelectric nanogenerator (PNG) is built on the single PMN-PT nanobelt, generating a maximum output voltage of ~1.2 V. This value is ~4 times higher than that of a single-CdTe PNG, ~13 times higher than that of a single-ZnSnO3 PNG, and ~26 times higher than that of a single-ZnO PNG. The profoundly increased output voltage of a lateral PNG built on a single PMN-PT nanobelt demonstrates the potential application of PMN-PT nanostructures in energy harvesting, thus enriching the material choices for PNGs.

  10. Synthesis and characterization of graphite-like carbon nitride nanobelts and nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Jie; Cao, Chuanbao; Zhu, Hesun

    2007-03-01

    Carbon nitride nanobelts and nanotubes were synthesized through polycondensation of dicyandiamide (H4C2N4) and melamine (C3N6H6) at 290 °C and 4.5-5 MPa. The as-synthesized samples were investigated by powder x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, elemental analysis and photoluminescence spectra. The results indicate that a new kind of graphite-like carbon nitride nanobelt and nanotube has been synthesized. The widths of the nanobelts range from 100 nm to 3 µm, the thickness is about 5-50 nm, and lengths range from several micrometres to tens of micrometres or longer. The nanotubes have outer diameters of 70-200 nm, inner diameters of 5-20 nm, and lengths of several micrometres. These nanobelts and nanotubes have luminescent properties and may have potential uses as components of optical nanoscale devices. The mechanism of formation is also investigated.

  11. Zn doped MoO3 nanobelts and the enhanced gas sensing properties to ethanol

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Liu, Yueli; Chen, Tao; Jin, Wei; Yang, Tingqiang; Cao, Minchi; Liu, Shunshun; Zhou, Jing; Zakharova, Galina S.; Chen, Wen

    2017-01-01

    Zn doped MoO3 nanobelts with the thickness of 120-275 nm, width of 0.3-1.4 μm and length of more than 100 μm are prepared by hydrothermal reaction. The operating temperature of sensors based on Zn doped MoO3 nanobelts is 100-380 °C with a better response to low concentration of ethanol. The highest response value of sensors based on Zn doped MoO3 to 1000 ppm ethanol at 240 °C is 321, which is about 15 times higher than that of pure MoO3 nanobelts. The gas sensors based on Zn doped MoO3 nanobelts possess good selectivity to ethanol compared with methanol, ammonia, acetone and toluene, which implies that it would be a good candidate in the potential application. The improvement of gas sensing properties may be attributed to the increasing absorbed ethanol, the decreasing probability of ethoxy recombination, the promoted dehydrogenation progress at lower temperature, and the narrowed band gap by Zn doping.

  12. Gap States Assisted MoO3 Nanobelt Photodetector with Wide Spectrum Response

    PubMed Central

    Xiang, Du; Han, Cheng; Zhang, Jialin; Chen, Wei

    2014-01-01

    Molybdenum oxides have been widely investigated for their broad applications ranging from electronics to energy storage. Photodetectors based on molybdenum trioxide (MoO3), however, were seldom reported owing to their low conductivity and weak photoresponse. Herein we report a photodetector based on single MoO3 nanobelt with wide visible spectrum response by introducing substantial gap states via H2 annealing. The pristine MoO3 nanobelt possessed low electrical conductance and no photoresponse for nearly all visible lights. The H2 annealing can significantly improve the conductance of MoO3 nanobelt, and result in a good photodetector with wide visible spectrum response. Under illumination of 680 nm light, the photodetector exhibited high responsivity of ~56 A/W and external quantum efficiency of ~10200%. As corroborated by in situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy investigations, such strong wide spectrum photoresponse arises from the largely enriched gap states in the MoO3 nanobelt after H2 annealing. PMID:24809461

  13. Synthesis and electrochemical performance of cable-like copper vanadates/polypyrrole nanobelts as anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Shaoyan; Hou, Menghua; Hou, Linlin; Lu, Min

    2016-08-01

    Cable-like CuV2O6/polypyrrole (CVO/PPy) nanobelts have been synthesized via in-situ oxidative polymerization of pyrrole monomers on the surface of hydrothermally synthesized α-CuV2O6 (CVO) nanobelts. The microscope analysis revealed that the diameter of cable-like CVO/PPy nanobelts focused on 80-110 nm and the shell thickness was about 10-30 nm. The electrochemical properties of the cable-like CVO/PPy nanobelts as anode materials were systematically investigated and compared with bare α-CuV2O6 nanobelts. It was found that the electrochemical performance of the CVO/PPy nanobelts was significantly enhanced. The results suggest that the conductive PPy nanolayer coating help to preserve high capacity, maintain high electrochemical stability, and reduce charge transfer resistance during cycling performance.

  14. Facile solution synthesis and photoelectric properties of monolithic tin(II) sulfide nanobelt arrays.

    PubMed

    Zhang, Xing; Yang, Long; Jiang, Yan; Yu, Bin-Bin; Zou, Yu-Gang; Fang, Ying; Hu, Jin-Song; Wan, Li-Jun

    2013-10-01

    The tremendous future energy demand and environmental concerns prompt the lasting search for new materials for low-cost and high-efficiency solar cells. SnS, as a low-cost, earth-abundant, and environmentally friendly material with proper band gap and absorption coefficient, has received attention as a potential candidate for solar absorber, but it is still under-developed due to insufficient conversion efficiency. Fabricating SnS nanostructured films for solar cell design could be effective to boost photovoltaic performance and pave the way for applications in photovoltaics. Herein, a facile surfactant-free solution-based approach has been developed to prepare monolithic SnS nanostructured films directly on tin foil substrate. The morphologies of nanostructured films could be tuned from well-defined orthorhombic SnS nanobelt arrays to nanorods, nanosheets, or nanoflakes by simply changing the ratio of used solvents. The photoelectric response and electronic transportation properties of SnS nanobelts were investigated by fabricating single-nanobelt-based nanodevices. The SnS nanobelt exhibited a fast and reliable photoresponse even at illumination intensity as weak as 0.103 mW cm(-2). The measurements on SnS FET devices also indicated that the synthesized SnS nanobelts demonstrated a hole mobility as high as 12.33 cm(2) V(-1) s(-1). These results reveal that the reported approach for preparing monolithic SnS nanostructured films could be useful to further develop SnS as an alternative material for low-cost solar cells and electronic devices.

  15. Enhanced electrochemical performance of orientated VO2(B) raft-like nanobelt arrays through direct lithiation for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Liang; Liu, Qiang; Zhao, Wen; Li, Guochun; Wang, Limei; Shi, Weidong; Chen, Long

    2017-02-01

    Lithiation modification of VO2(B) has been carried out by a facile hydrothermal process, and the compact and locally ordered VO2(B) raft-like nanobelt arrays have been prepared. The synthesis route provides a new approach to elaborate a VO2(B) nanostructure under a mild environment condition. It is found that the growth mechanism of VO2(B) raft-like nanobelt arrays is different from the traditional nucleation-growth process. A novel chemical lithiating-exfoliating-splitting model is proposed. Compared with the bulk counterpart, the lithiated VO2(B) raft-like nanobelt arrays as cathodes exhibit a higher discharge capacity and an enhanced high-rate performance owing to their increased structural anisotropy and decreased polarization. This work indicates that VO2(B) raft-like nanobelt arrays have great potential applications as cathode materials for lithium ion batteries.

  16. Enhanced electrochemical performance of orientated VO2(B) raft-like nanobelt arrays through direct lithiation for lithium ion batteries.

    PubMed

    Liu, Liang; Liu, Qiang; Zhao, Wen; Li, Guochun; Wang, Limei; Shi, Weidong; Chen, Long

    2017-02-10

    Lithiation modification of VO2(B) has been carried out by a facile hydrothermal process, and the compact and locally ordered VO2(B) raft-like nanobelt arrays have been prepared. The synthesis route provides a new approach to elaborate a VO2(B) nanostructure under a mild environment condition. It is found that the growth mechanism of VO2(B) raft-like nanobelt arrays is different from the traditional nucleation-growth process. A novel chemical lithiating-exfoliating-splitting model is proposed. Compared with the bulk counterpart, the lithiated VO2(B) raft-like nanobelt arrays as cathodes exhibit a higher discharge capacity and an enhanced high-rate performance owing to their increased structural anisotropy and decreased polarization. This work indicates that VO2(B) raft-like nanobelt arrays have great potential applications as cathode materials for lithium ion batteries.

  17. Engineering the Electrical Conductivity of Lamellar Silver-Doped Cobalt(II) Selenide Nanobelts for Enhanced Oxygen Evolution.

    PubMed

    Zhao, Xu; Zhang, Hantao; Yan, Yu; Cao, Jinhua; Li, Xingqi; Zhou, Shiming; Peng, Zhenmeng; Zeng, Jie

    2017-01-02

    Precisely engineering the electrical conductivity represents a promising strategy to design efficient catalysts towards oxygen evolution reaction (OER). Here, we demonstrate a versatile partial cation exchange method to fabricate lamellar Ag-CoSe2 nanobelts with controllable conductivity. The electrical conductivity of the materials was significantly enhanced by the addition of Ag(+) cations of less than 1.0 %. Moreover, such a trace amount of Ag induced a negligible loss of active sites which was compensated through the effective generation of active sites as shown by the excellent conductivity. Both the enhanced conductivity and the retained active sites contributed to the remarkable electrocatalytic performance of the Ag-CoSe2 nanobelts. Relative to the CoSe2 nanobelts, the as-prepared Ag-CoSe2 nanobelts exhibited a higher current density and a lower Tafel slope towards OER. This strategy represents a rational design of efficient electrocatalysts through finely tuning their electrical conductivities.

  18. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites

    PubMed Central

    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

    2016-01-01

    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data. PMID:26907290

  19. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites.

    PubMed

    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

    2016-02-20

    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.

  20. Synthesis of porous and nonporous ZnO nanobelt, multipod, and hierarchical nanostructure from Zn-HDS

    SciTech Connect

    Jang, Eue-Soon; Won, Jung-Hee; Kim, Young-Woon; Cheng, Zhen; Choy, Jin-Ho

    2010-08-15

    Zn based hydroxide double salts (Zn-HDS) with an interlayer spacing of 20 A was produced by dissolving dumbbell-like ZnO crystal. The resulting Zn-HDS with a ribbon-like shape has a suitable morphology to explore the remarkably mild procedure for synthesis of ZnO nanobelts. We found that the intercalated water molecules into the Zn-HDS could play a key role in the ZnO nanobelts porosity. The nonporous ZnO nanobelts were successfully synthesized from the Zn-HDS by soft-solution process at 95 {sup o}C through mild dehydration agent as Na{sub 2}CO{sub 3}. As-synthesized ZnO nanobelts were grown along not only the [0 1 -1 0], but also the [2 -1 -1 0]. On the other hand, the porous ZnO nanobelts were obtained from the Zn-HDS by calcinations at 200 and 400 {sup o}C. In addition, flower-like ZnO multipod and hierarchical nanostructures were produced from the Zn-HDS by using of strong dehydration agent (NaOH) through hydrothermal reaction at 150 and 230 {sup o}C. - Graphical abstract: Porous and nonporous ZnO nanobelts, multipod, and hierarchical nanostructure were successfully synthesized from Zn based hydroxyl double salts by hydrothermal reaction.

  1. Vapor-phase synthesis, growth mechanism and thickness-independent elastic modulus of single-crystal tungsten nanobelts.

    PubMed

    Wang, Shiliang; Chen, Guoliang; Huang, Han; Ma, Shujun; Xu, Hongyi; He, Yuehui; Zou, Jin

    2013-12-20

    Single-crystal tungsten nanobelts with thicknesses from tens to hundreds of nanometers, widths of several micrometers and lengths of tens of micrometers were synthesized using chemical vapor deposition. Surface energy minimization was believed to have played a crucial role in the growth of the synthesized nanobelts enclosed by the low-energy {110} crystal planes of body-centered-cubic structure. The anisotropic growth of the crystallographically equivalent {110} crystal planes could be attributable to the asymmetric concentration distribution of the tungsten atom vapor around the nanobelts during the growth process. The elastic moduli of the synthesized tungsten nanobelts with thicknesses ranging from 65 to 306 nm were accurately measured using a newly developed thermal vibration method. The measured modulus values of the tungsten nanobelts were thickness-dependent. After eliminating the effect of surface oxidization using a core-shell model, the elastic modulus of tungsten nanobelts became constant, which is close to that of the bulk tungsten value of 410 GPa.

  2. Hydrothermal Synthesis of Silver Vanadium Oxide (Ag0.35V2O5) Nanobelts for Sensing Amines

    NASA Astrophysics Data System (ADS)

    Fu, Haitao; Xie, Hui; Yang, Xiaohong; An, Xizhong; Jiang, Xuchuan; Yu, Aibing

    2015-10-01

    A simple hydrothermal method for the synthesis of Ag0.35V2O5 nanobelts with the assistance of sodium dodecyl sulfate (SDS) is reported in this study. The experimental variables that may affect the nanoparticle structures were investigated. And several advanced techniques, such as TEM, HRTEM, X-ray diffraction (XRD), were used to characterize the morphology and composition of the as-prepared nanobelts. The mechanism of the formation and growth of Ag0.35V2O5 nanobelts was also investigated and discussed. The results show that SDS, as a weak reducing agent, plays a crucial role in the formation of Ag0.35V2O5. According to N2 sorption isothermals, the as-prepared Ag0.35V2O5 nanobelts are found to exhibit relative high surface area. The gas sensing performance of the Ag0.35V2O5 nanobelts towards organic amine was tested. It is found that the nanobelts show superior sensitivity of amine(s) to V2O5 particles, lower detection limit (5 ppm), and higher selectivity of amine versus ammonia at an optimized working temperature of ~260 °C. Moreover, the density functional theory (DFT) simulation was conducted to better understand the sensing mechanism. These findings may be useful in designing promising materials to detect amine gases for medical or food industrial applications.

  3. Electrochemical performance of new α-MoO3 nanobelt cathode materials for rechargeable Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Nadimicherla, Reddeppa; Liu, Yueli; Chen, Keqiang; Chen, Wen

    2014-08-01

    The orthorhombic molybdenum trioxide (α-MoO3) nanobelts and polyvinyl pyrrolidone (PVP) surfactant MoO3 nanobelts with high quality were prepared through hydrothermal synthesis. The morphology and microstructure of the samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The nanobelts with rectangular cross-section have an orthorhombic phase structure, preferentially grow in [001] direction. The results showed that the H atoms in polyvinyl pyrrolidone are H-bonded with the O atoms in the Modbnd O bonds of MoO3 nanobelts. When MoO3 is modified by the intercalation of PVP, it is effectively shielded against electrostatic interaction between the MoO3 interlayer and Li+ ions. The specific capacity of pure MoO3 nanobelts battery and (PVP)0.2MoO3 nanobelts exhibit as 195 mAh g-1 and 237 mAh g-1, respectively after 14 cycles, suggests that the stability of surfactant material is worthy.

  4. Electrothermally-Actuated Micromirrors with Bimorph Actuators--Bending-Type and Torsion-Type.

    PubMed

    Tsai, Cheng-Hua; Tsai, Chun-Wei; Chang, Hsu-Tang; Liu, Shih-Hsiang; Tsai, Jui-Che

    2015-06-22

    Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively.

  5. Automated in-situ optimization of bimorph mirrors at Diamond Light Source

    NASA Astrophysics Data System (ADS)

    Sutter, John P.; Alcock, Simon G.; Sawhney, Kawal J. S.

    2011-09-01

    Bimorph mirrors are used on many synchrotron beamlines to focus or collimate light. They are highly adaptable because not only their overall figure but also their local slope errors can be corrected. However, the optimization procedure is complex. At Diamond Light Source, highly repeatable and accurate pencil beam measurements are used to determine a mirror's slope errors. These data are then used by automated scripts to calculate the necessary corrections. This procedure may be applied to any type of active mirror, but for hard X-ray mirrors, diffraction from the slits must be considered.

  6. Electrothermally-Actuated Micromirrors with Bimorph Actuators—Bending-Type and Torsion-Type

    PubMed Central

    Tsai, Cheng-Hua; Tsai, Chun-Wei; Chang, Hsu-Tang; Liu, Shih-Hsiang; Tsai, Jui-Che

    2015-01-01

    Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively. PMID:26110409

  7. The effects of first-order strain gradient in micro piezoelectric-bimorph power harvesters.

    PubMed

    Hu, Yuantai; Wang, Jining; Yang, Feng; Xue, Huan; Hu, Hongping; Wang, Ji

    2011-04-01

    The effects of first-order strain gradient in micro piezoelectric-bimorph (PB) power harvesters are investigated by including the first-order gradient terms in the energy density functions. For a PB, the gradient effects can be focused on the analysis of the strain gradient effect in the thickness direction through choosing the strains and the electric displacements as the independent constitutive variables. It is shown theoretically that the first-order gradient effects have raised the natural frequency of the PB and effectively enhanced the output power density of the harvester.

  8. Study of oscillatory piezoelectric flow pumps using bimorph actuators with different tip geometries

    NASA Astrophysics Data System (ADS)

    Pires, Rogério F.; Koga, Adriano A.; Nakasone, Paulo H.; Silva, Emílio C. N.

    2008-03-01

    Precision flow pumps have been widely studied over the last three decades. They have been applied in the areas of Biology, Pharmacy and Medicine in applications usually related to the dosage of medicine and chemical reagents. In addition, thermal management solutions for electronic devices have also been recently developed using these kinds of pumps offering better performance with low noise and low power consumption. In a previous work, the working principle of a pump based on the use of bimorph piezoelectric actuators inserted in a fluid channel to generate flow was presented. The present work aims at the development of novel configurations of piezoelectric flow pumps based on the use of bimorph actuators with biomimetic tip geometries that are inspired in fish caudal fin shapes, such as ostraciiform, subcarangiform, carangiform and thunniform. The pump development consists in designing, manufacturing and experimental characterization steps. In the design step, computational models of pump configurations are built to perform sensitivity studies and to apply optimization techniques using ANSYS finite element analysis software. The prototype manufacturing is guided by the computational simulations. Electronic circuits for pump electrical excitation and control are developed and implemented. Comparisons among numerical and experimental results are also made.

  9. Ion-assisted coating for large-scale Bimorph deformable mirror

    NASA Astrophysics Data System (ADS)

    Mikami, Takuya; Okamoto, Takayuki; Yoshida, Kunio; Jitsuno, Takahisa; Motokoshi, Shinji; Samarkin, Vadim V.; Kudryashov, Alexis V.; Kawanaka, Junji; Miyanaga, Noriaki

    2016-07-01

    We have fabricated a 410 x 468 mm size deformable mirror with 100 Bimorph piezoceramic actuators for the LFEX laser system at Osaka University. In the case of Bimorph-type deformable mirrors, the mirror surface had to be polished and coated after bonding the piezoceramic actuators to the rear side of the thin mirror substrate. This provides a good surface figure, but the coating temperature for the high-reflection mirror was strictly limited because of the thermal fragility of piezoceramic actuators. The mirror substrate with the actuators was polished, and an ion-assisted multilayer dielectric coating was produced at 60 degrees Celsius with our 80-inch coating chamber. The flatness of the mirror just after coating was 7 μm, and reduced by aging to 3.2 μm when the mirror was assembled. The surface figure of the assembled mirror with 20 piezostack bonded actuators is demonstrated and a laser-induced damage threshold tested with a witness sample is also reported.

  10. Research on the optimization of a bimorph piezoelectric deformable mirror based on zeroth-order method

    NASA Astrophysics Data System (ADS)

    Wang, Hairen; Hu, Lin

    2016-07-01

    The deformable mirror adjusts the mirror surface shape to compensate the wavefront error in the adaptive optics system. Recently, the adaptive optics has been widely used in many applications, such as astronomical telescopes, high power laser systems, etc. These applications require large diameter deformable mirrors with large stroke, high speed and low cost. Thus, the bimorph piezoelectric deformable mirror, which is a good match for the applications, has attracted more and more attentions. In this paper, we use zeroth-order optimization method to optimize the physical parameters of a bimorph piezoelectric deformable mirror that consists of a metal reflective layer deposited on the top of a slim piezoelectric ceramic surface layer. The electrodes are deposited on the bottom of the piezoelectric ceramic layer. The physical parameters to be optimized include the optimal thickness ratio between the piezoelectric layer and reflective layer, inter-electrode distance, and so on. A few reasonable designs are obtained by a comparative study presented for three geometries of electrodes, which are circular, square and hexagon, respectively.

  11. Fabrication and Characterization of Nitinol-Copper Shape Memory Alloy Bimorph Actuators

    NASA Astrophysics Data System (ADS)

    Wongweerayoot, E.; Srituravanich, W.; Pimpin, A.

    2015-02-01

    This study aims to examine the effect of annealing conditions on nitinol (NiTi) characteristics and applies this knowledge to fabricate a NiTi-copper shape memory alloy bimorph actuator. The effect of the annealing conditions was investigated at various temperatures, i.e., 500, 600, and 650 °C, for 30 min. With the characterizations using x-ray diffraction, energy dispersive spectroscopy, and differential scanning calorimetry techniques, the results showed that annealing temperatures at 600 and 650 °C were able to appropriately form the crystalline structure of NiTi. However, at these high annealing temperatures, the oxide on a surface was unavoidable. In the fabrication of actuator, the annealing at 650 °C for 30 min was chosen, and it was performed at two pre-stressing conditions, i.e., straight and curved molds. From static and dynamic response experiments, the results suggested that the annealing temperature significantly affected the deflection of the actuator. On the other hand, the effect of pre-stressing conditions was relatively small. Furthermore, the micro gripper consisting of two NiTi-copper bimorph actuators successfully demonstrated for the viability of small object manipulation as the gripper was able to grasp and hold a small plastic ball with its weight of around 0.5 mg.

  12. Construction of a Fish-like Robot Based on High Performance Graphene/PVDF Bimorph Actuation Materials.

    PubMed

    Xiao, Peishuang; Yi, Ningbo; Zhang, Tengfei; Huang, Yi; Chang, Huicong; Yang, Yang; Zhou, Ying; Chen, Yongsheng

    2016-06-01

    Smart actuators have many potential applications in various areas, so the development of novel actuation materials, with facile fabricating methods and excellent performances, are still urgent needs. In this work, a novel electromechanical bimorph actuator constituted by a graphene layer and a PVDF layer, is fabricated through a simple yet versatile solution approach. The bimorph actuator can deflect toward the graphene side under electrical stimulus, due to the differences in coefficient of thermal expansion between the two layers and the converse piezoelectric effect and electrostrictive property of the PVDF layer. Under low voltage stimulus, the actuator (length: 20 mm, width: 3 mm) can generate large actuation motion with a maximum deflection of about 14.0 mm within 0.262 s and produce high actuation stress (more than 312.7 MPa/g). The bimorph actuator also can display reversible swing behavior with long cycle life under high frequencies. on this basis, a fish-like robot that can swim at the speed of 5.02 mm/s is designed and demonstrated. The designed graphene-PVDF bimorph actuator exhibits the overall novel performance compared with many other electromechanical avtuators, and may contribute to the practical actuation applications of graphene-based materials at a macro scale.

  13. Production of large-scale, freestanding vanadium pentoxide nanobelt porous structures.

    PubMed

    Yun, Yong Ju; Kim, Byung Hoon; Hong, Won G; Kim, Chang Hee; Kim, Yark Yeon; Jeong, Eun-ju; Jang, Won Ick; Yu, Han Young

    2012-03-07

    Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm(-3) and 40-80 m(2) g(-1), respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface.

  14. Production of large-scale, freestanding vanadium pentoxide nanobelt porous structures

    NASA Astrophysics Data System (ADS)

    Yun, Yong Ju; Kim, Byung Hoon; Hong, Won G.; Kim, Chang Hee; Kim, Yark Yeon; Jeong, Eun-Ju; Jang, Won Ick; Yu, Han Young

    2012-02-01

    Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm-3 and 40-80 m2 g-1, respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface.

  15. Carbon-coated SnO2 nanobelts and nanoparticles by single catalytic step

    NASA Astrophysics Data System (ADS)

    Carreño, Neftali L. V.; Nunes, Michael R.; Garcia, Irene T. S.; Orlandi, Marcelo O.; Fajardo, Humberto V.; Longo, Elson

    2009-05-01

    Several types of carbon nanostructures (amorphous and graphitic), for the coating of SnO2 nanobelts and nanoparticles were obtained by a single catalytic process, during methane, natural gas, and methanol decomposition using the reactivity of surface-modified SnO2 nanostructure as a nanotemplate. The nanostructured catalyst templates were based on transition metal nanoparticles supported on SnO2 nanobelts previously prepared by a carbothermal reduction process. Carbon-coated SnO2 nanopowders were also successfully synthesized for the fabrication of carbon spheres. The carbon coating process and yield, along with the nature of the nanostructured carbon, are strongly influenced by the chemically modified surface of the SnO2 nanostructure template and the chemical reaction gas composition. The preliminary catalytic activity and gas-sensing properties of these novel materials based on metal nanoparticles and carbon-coated SnO2 were determined.

  16. Solid-state semiconductor optical cryocooler based on CdS nanobelts.

    PubMed

    Li, Dehui; Zhang, Jun; Wang, Xinjiang; Huang, Baoling; Xiong, Qihua

    2014-08-13

    We demonstrate the laser cooling of silicon-on-insulator (SOI) substrate using CdS nanobelts. The local temperature change of the SOI substrate exactly beneath the CdS nanobelts is deduced from the ratio of the Stokes and anti-Stokes Raman intensities from the Si layer on the top of the SOI substrate. We have achieved a 30 and 20 K net cooling starting from 290 K under a 3.8 mW 514 nm and a 4.4 mW 532 nm pumping, respectively. In contrast, a laser heating effect has been observed pumped by 502 and 488 nm lasers. Theoretical analysis based on the general static heat conduction module in the Ansys program package is conducted, which agrees well with the experimental results. Our investigations demonstrate the laser cooling capability of an external thermal load, suggesting the applications of II-VI semiconductors in all-solid-state optical cryocoolers.

  17. Raman selection rule for surface optical phonons in ZnS nanobelts

    NASA Astrophysics Data System (ADS)

    Ho, Chih-Hsiang; Varadhan, Purushothaman; Wang, Hsin-Hua; Chen, Cheng-Ying; Fang, Xiaosheng; He-Hau, Jr.

    2016-03-01

    We report Raman scattering results for high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In the Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition to a strong surface optical (SO) phonon mode at 329 cm-1. The existence of the SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectra were recorded on a single ZnS NB and for the first time a SO phonon band has been detected on a single nanobelt. Different selection rules for the SO phonon mode are shown from their corresponding E1/A1 phonon modes, and were attributed to the breaking of anisotropic translational symmetry on the NB surface.

  18. A novel polytype - the stacking fault based γ-MoO3 nanobelts.

    PubMed

    Sławiński, Wojciech A; Fjellvåg, Øystein S; Ruud, Amund; Fjellvåg, Helmer

    2016-04-01

    γ-MoO3 nanobelts prepared by hydrothermal synthesis were studied by synchrotron radiation powder diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction. Their nm dimensions, in particular in two crystallographic directions, have a profound influence on electrochemical properties during cycling as the cathode material in lithium-ion batteries (LIBs). The diffraction analysis shows clearly that the crystal structure for the γ-MoO3 nanobelts differs significantly from that of bulk α-MoO3. The observed powder diffraction pattern, with asymmetric peaks, extremely broad peaks, as well as additional or absent diffraction peaks, is fully described by means of a model based on stacking disorder of MoO3 slabs.

  19. S-induced modifications of the optoelectronic properties of ZnO mesoporous nanobelts

    PubMed Central

    Fabbri, Filippo; Nasi, Lucia; Fedeli, Paolo; Ferro, Patrizia; Salviati, Giancarlo; Mosca, Roberto; Calzolari, Arrigo; Catellani, Alessandra

    2016-01-01

    The synthesis of ZnO porous nanobelts with high surface-to-volume ratio is envisaged to enhance the zinc oxide sensing and photocatalytic properties. Yet, controlled stoichiometry, doping and compensation of as-grown n-type behavior remain open problems for this compound. Here, we demonstrate the effect of residual sulfur atoms on the optical properties of ZnO highly porous, albeit purely wurtzite, nanobelts synthesized by solvothermal decomposition of ZnS hybrids. By means of combined cathodoluminescence analyses and density functional theory calculations, we attribute a feature appearing at 2.36 eV in the optical emission spectra to sulfur related intra-gap states. A comparison of different sulfur configurations in the ZnO matrix demonstrates the complex compensating effect on the electronic properties of the system induced by S-inclusion. PMID:27301986

  20. Bifunctional Ag/C3N4.5 composite nanobelts for photocatalysis and antibacterium

    NASA Astrophysics Data System (ADS)

    Lei, Renbo; Jian, Jikang; Zhang, Zhihua; Song, Bo; Wu, Rong

    2016-09-01

    Multiple functions can be achieved in carbon nitride-based composite nanomaterials by tuning their components and structures. Here, we report on a large-scale synthesis of novel bifunctional Ag/C3N4.5 composite nanobelts (CNBs) with efficient photocatalytic and antibacterial activity. The Ag/C3N4.5 CNBs were synthesized in high yield by a two-step route including a homogeneous precipitation process and a subsequent calcination treatment. The structural, morphological, compositional, and spectroscopic characterizations revealed that the Ag/C3N4.5 CNBs are composed of N-deficient melem ultrathin nanobelts and crystalline Ag nanoparticles attached to the surface of the nanobelts with good contact. The band gap of the Ag/C3N4.5 CNBs is determined to be about 3.04 eV. The efficient photocatalytic and antibacterial activities of the composite nanomaterials are verified by testing the degradation of Rhodamine B (RhB) and the inhibition zone to bacterium E. coli. The work provides a facile route to bifunctional carbon nitride-based composites with potential applications in the fields of the environment and biology.

  1. Bifunctional Ag/C3N4.5 composite nanobelts for photocatalysis and antibacterium.

    PubMed

    Lei, Renbo; Jian, Jikang; Zhang, Zhihua; Song, Bo; Wu, Rong

    2016-09-30

    Multiple functions can be achieved in carbon nitride-based composite nanomaterials by tuning their components and structures. Here, we report on a large-scale synthesis of novel bifunctional Ag/C3N4.5 composite nanobelts (CNBs) with efficient photocatalytic and antibacterial activity. The Ag/C3N4.5 CNBs were synthesized in high yield by a two-step route including a homogeneous precipitation process and a subsequent calcination treatment. The structural, morphological, compositional, and spectroscopic characterizations revealed that the Ag/C3N4.5 CNBs are composed of N-deficient melem ultrathin nanobelts and crystalline Ag nanoparticles attached to the surface of the nanobelts with good contact. The band gap of the Ag/C3N4.5 CNBs is determined to be about 3.04 eV. The efficient photocatalytic and antibacterial activities of the composite nanomaterials are verified by testing the degradation of Rhodamine B (RhB) and the inhibition zone to bacterium E. coli. The work provides a facile route to bifunctional carbon nitride-based composites with potential applications in the fields of the environment and biology.

  2. Oriented free-standing ammonium vanadium oxide nanobelt membranes: highly selective absorbent materials.

    PubMed

    Zou, Rujia; Zhang, Zhenyu; Yu, Li; Tian, Qiwei; Wu, Jianghong; Sun, Yangang; Chen, Zhigang; Hu, Junqing

    2010-12-27

    Highly selective, absorbent, free-standing, paper-like membranes made of ammonium vanadium oxide (NH(4)V(4)O(14)) nanobelts have been engineered by taking advantage of the nanoscaled self-assembly of architectures that display a mesh structure with an average periodic pore size of about 5 to 10 nm. The NH(4)V(4)O(14) nanobelts are synthesized by using a simple hydrothermal process, and exhibit the same orientation and assemble into bundles, each about 40 to 80 nm in width, 3 to 5 nm in thickness, and up to several millimeters in length. Importantly, the as-obtained NH(4)V(4)O(14) nanobelt membranes can highly selectively absorb a variety of organic solvents, covering both polar and non-polar solvents, for example, the absorbent capacity of glycol is 28 times as high as the initial weight of the membrane, and it can even separate organic solvents with similar polarities and absorb solid contaminants in organic solvents. These highly selective, absorbent membrane materials can be an ideal candidate for the separation and removal of pollution in industrial and environmental applications.

  3. Synthesis and Gas Sensing Properties of Single La-Doped SnO₂ Nanobelts.

    PubMed

    Wu, Yuemei; Zhang, Heng; Liu, Yingkai; Chen, Weiwu; Ma, Jiang; Li, Shuanghui; Qin, Zhaojun

    2015-06-16

    Single crystal SnO2 nanobelts (SnO2 NBs) and La-SnO2 nanobelts (La-SnO2 NBs) were synthesized by thermal evaporation. Both a single SnO2 NB sensor and a single La-SnO2 NB sensor were developed and their sensing properties were investigated. It is found that the single La-SnO2 NB sensor had a high sensitivity of 8.76 to ethanediol at a concentration of 100 ppm at 230 °C, which is the highest sensitivity of a single SnO2 NB to ethanediol among three kinds of volatile organic (VOC) liquids studied, including ethanediol, ethanol, and acetone. The La-SnO2 NBs sensor also exhibits a high sensitivity, good selectivity and long-term stability with prompt response time to ethanediol. The mechanism behind the enhanced sensing performance of La-doped SnO2 nanobelts is discussed.

  4. Hydrogen gas sensors from polysilicon nanobelt devices selectively modified with sensing materials

    NASA Astrophysics Data System (ADS)

    Tran, Nhan Ai; Pan, Fu-Ming; Sheu, Jeng-Tzong

    2016-12-01

    Double-junction n+/n-/n+ polysilicon nanobelts featuring selectively deposited sensing materials have been investigated for application as H2 gas sensors. The selective modification of the devices was performed through a combination of localized ablation of a resist and lift-off of a previous catalyst material deposited through e-beam evaporation. Four nanobelt devices, differentiated by their doping concentrations at the n- region (from 2.5 × 1013 to 2.5 × 1014 cm-2), were analyzed in terms of the responses to H2 and their self-heating effects. A low doping concentration improved the response at room temperature, owing to a longer Debye length. The variation in the H2-induced surface potential associated with temperature, accounting for degradation in the response of the nanobelts with Joule heating bias, was analyzed in terms of the I-V characteristics of the double-junction device. Among various catalysts (Pt, Pd, Pt/Pd) evaluated for their H2 sensing characteristics, an ultrathin film of Pt/Pd was most favorable.

  5. Ultrathin Na1.1V3O7.9 nanobelts with superior performance as cathode materials for lithium-ion batteries.

    PubMed

    Liang, Shuquan; Zhou, Jiang; Fang, Guozhao; Liu, Jing; Tang, Yan; Li, Xilin; Pan, Anqiang

    2013-09-11

    The Na1.1V3O7.9 nanobelts have been synthesized by a facile and scalable hydrothermal reaction with subsequent calcinations. The morphologies and the crystallinity of the nanobelts are largely determined by the calcination temperatures. Ultrathin nanobelts with a thickness around 20 nm can be obtained, and the TEM reveals that the nanobelts are composed of many stacked thinner belts. When evaluated as a cathode material for lithium batteries, the Na1.1V3O7.9 nanobelts exhibit high specific capacity, good rate capability, and superior long-term cyclic stability. A high specific capacity of 204 mA h g(-1) can be delivered at the current density of 100 mA g(-1). It shows excellent capacity retention of 95% after 200 cycles at the current density of 1500 mA g(-1). As demonstrated by the ex situ XRD results, the Na1.1V3O7.9 nanobelts have very good structural stability upon cycling. The superior electrochemical performances can be attributed to the ultra-thin nanobelts and the good structural stability of the Na1.1V3O7.9 nanobelts.

  6. Electric-field-dependent photoconductivity in CdS nanowires and nanobelts: exciton ionization, Franz-Keldysh, and Stark effects.

    PubMed

    Li, Dehui; Zhang, Jun; Zhang, Qing; Xiong, Qihua

    2012-06-13

    We report on the electric-field-dependent photoconductivity (PC) near the band-edge region of individual CdS nanowires and nanobelts. The quasi-periodic oscillations above the band edge in nanowires and nanobelts have been attributed to a Franz-Keldesh effect. The exciton peaks in PC spectra of the nanowires and thinner nanobelts show pronounced red-shifting due to the Stark effect as the electric field increases, while the exciton ionization is mainly facilitated by strong electron-longitudinal optical (LO) phonon coupling. However, the band-edge transition of thick nanobelts blue-shifts due to the field-enhanced exciton ionization, suggesting partial exciton ionization as the electron-LO phonon coupling is suppressed in the thicker belts. Large Stark shifts, up to 48 meV in the nanowire and 12 meV in the thinner nanobelts, have been achieved with a moderate electric field on the order of kV/cm, indicating a strong size and dimensionality implication due to confinement and surface depletion.

  7. Primary bimorphic adrenocortical disease: cause of hypercortisolism in McCune-Albright syndrome.

    PubMed

    Carney, J Aidan; Young, William F; Stratakis, Constantine A

    2011-09-01

    McCune-Albright syndrome (polyostotic fibrous dysplasia, café-au-lait skin spots, and precocious puberty) is a genetically mosaic disorder with populations of mutant and normal cells in affected organs. Cushing syndrome, a rare feature of the condition, usually affects infants and is the result of corticotropin-independent primary bilateral adrenal disease, usually interpreted as nodular adrenocortical hyperplasia. In this study of 9 patients with Cushing syndrome and McCune-Albright syndrome, light microscopy revealed a characteristic bimorphic pattern of diffuse and nodular hyperplasia and a distinctive form of cortical atrophy with apparent zona glomerulosa hyperplasia in 8 patients, all very young. The pattern could be explained by the presence of a mosaic distribution of mutant and normal cells in the adrenal glands. The findings are different from those in inherited or other forms of genetically caused Cushing syndrome. The ninth patient, aged 17 years, had an adrenal adenoma and diffuse cortical hyperplasia in each adrenal gland.

  8. Compact, planar, translational piezoelectric bimorph actuator with Archimedes’ spiral actuating tethers

    NASA Astrophysics Data System (ADS)

    Yang, Chenye; Liu, Sanwei; Xie, Xin; Livermore, Carol

    2016-12-01

    The design, analytical modelling, finite element analysis (FEA), and experimental characterization of a microelectromechanical system (MEMS) out-of-plane (vertical) translational piezoelectric lead-zirconate-titanate (PZT) bimorph actuator supported on Archimedes’ spiral tethers are presented. Three types of bimorph actuators with different electrode patterns (with spiral tethers half actuated, fully actuated with uniform polarity, or fully actuated with reversed polarity) are designed and modelled. The two actuators with the highest predicted performance (half actuated and fully actuated with uniform polarity) are implemented and characterized. Both designs are fabricated by commercial processes and are compatible with integration into more complex MEMS systems. Analytical modelling and FEA are used to analyze and predict the actuators’ displacements and blocking forces. Experimental measurements of the deflections and blocking forces of actuators with full uniform actuation and half actuation validate the design. At an applied voltage of 110 V, the out-of-plane deflections of the actuators with half actuation and full uniform actuation are measured at about 17 µm and 29 µm respectively, in good agreement with analytical predictions of 17.3 µm and 34.2 µm and FEA predictions of 17.1 µm and 25.8 µm. The blocking force for devices with half-actuated tethers is predicted to be 12 mN (analytical) and 10 mN (FEA), close to the experimental value of 9 mN. The blocking force for devices with full uniform actuation is predicted to be 23 mN (analytical) and 17 mN (FEA), as compared with 15 mN in experiments.

  9. Global nonlinear electroelastic dynamics of a bimorph piezoelectric cantilever for energy harvesting, sensing, and actuation

    NASA Astrophysics Data System (ADS)

    Leadenham, Stephen; Erturk, Alper

    2014-04-01

    Inherent nonlinearities of piezoelectric materials are inevitably pronounced in various engineering applications such as sensing, actuation, their combined applications for vibration control, and most recently, energy harvesting from dynamical systems. The existing literature focusing on the dynamics of electroelastic structures made of piezoelectric materials have explored such nonlinearities in a disconnected way for the separate problems of mechanical and electrical excitation such that nonlinear resonance trends have been assumed to be due to different additional terms in constitutive equations by different researchers. Similar manifestations of softening nonlinearities have been attributed to purely elastic nonlinear terms, coupling nonlinearities, hysteresis, or a combination of these effects, by various authors. However, a reliable nonlinear constitutive equation for a given piezoelectric material is expected to be rather unique and valid regardless of the application, e.g. energy harvesting, sensing, or actuation. A systematic approach focusing on the two-way coupling can result in a sound mathematical framework. To this end, the present work investigates the nonlinear dynamic behavior of a bimorph piezoelectric cantilever under low-to-high mechanical and electrical excitation levels in energy harvesting, sensing, and actuation. A physical model is proposed including both ferroelastic hysteresis, stiffness, and electromechanical coupling nonlinearities. A lumped parameter electroelastic model is developed by accounting for these nonlinearities to analyze the primary resonance of a cantilever using the method of harmonic balance. Strong agreement between the model and experimental investigation is found, providing solid evidence that the the dominant source of observed softening nonlinear effects in geometrically linear piezolectric cantilever beams is well represented by a quadratic term resulting from ferroelastic hysteresis. Electromechanical coupling and

  10. Theoretical modeling and equivalent electric circuit of a bimorph piezoelectric micromachined ultrasonic transducer.

    PubMed

    Sammoura, Firas; Kim, Sang-Gook

    2012-05-01

    An electric circuit model for a circular bimorph piezoelectric micromachined ultrasonic transducer (PMUT) was developed for the first time. The model was made up of an electric mesh, which was coupled to a mechanical mesh via a transformer element. The bimorph PMUT consisted of two piezoelectric layers of the same material, having equal thicknesses, and sandwiched between three thin electrodes. The piezoelectric layers, having the same poling axis, were biased with electric potentials of the same magnitude but opposite polarity. The strain mismatches between the two layers created by the converse piezoelectric effect caused the membrane to vibrate and, hence, transmit a pressure wave. Upon receiving the echo of the acoustic wave, the membrane deformation led to the generation of electric charges as a result of the direct piezoelectric phenomenon. The membrane angular velocity and electric current were related to the applied electric field, the impinging acoustic pressure, and the moment at the edge of the membrane using two canonical equations. The transduction coefficients from the electrical to the mechanical domain and vice-versa were shown to be bilateral and the system was shown to be reversible. The circuit parameters of the derived model were extracted, including the transformer ratio, the clamped electric impedance, the spring-softening impedance, and the open-circuit mechanical impedance. The theoretical model was fully examined by generating the electrical input impedance and average plate displacement curves versus frequency under both air and water loading conditions. A PMUT composed of piezoelectric material with a lossy dielectric was also investigated and the maximum possible electroacoustical conversion efficiency was calculated.

  11. Carrier transport in graphite/Si{sub 3}N{sub 4}-nanobelt/PtIr Schottky barrier diodes

    SciTech Connect

    Bi, Jinghui; Wei, Guodong; Shang, Minghui; Gao, Fengmei; Yang, Weiyou E-mail: weiyouyang@tsinghua.org.cn; Tang, Bin E-mail: weiyouyang@tsinghua.org.cn

    2014-11-10

    Understanding the roles of contacts and interfaces between metals and semiconductors is critically important for exploring nanostructure-based nanodevices. The present study shed some light on the dominated mechanism of size-dependent carrier transfer in the Schottky barrier diodes configured by the Pt-Ir/Si{sub 3}N{sub 4}-nanobelt/graphite (metal-semiconductor-metal (MSM)) sandwiched structure via a conductive atomic force microscopy using nanobelts with various thicknesses. The observed I-V behaviors suggested that the charge transports under the low and high biases were dominated by the reverse-biased Schottky barrier and space-charge-limited current (SCLC), respectively. The intermediate region between the low and high biases presented the transition between the Ohmic and SCLC behaviors, in which the ≡Si and =N dangling bonds acted as the defects within the Si{sub 3}N{sub 4} nanobelt surface are predominant in the charge transfer.

  12. Real-time observation of morphological transformations in II-VI semiconducting nanobelts via environmental transmission electron microscopy

    DOE PAGES

    Agarwal, Rahul; Zakharov, Dmitri N.; Krook, Nadia M.; ...

    2015-05-01

    It has been observed that wurtzite II–VI semiconducting nanobelts transform into single-crystal, periodically branched nanostructures upon heating. The mechanism of this novel transformation has been elucidated by heating II–VI nanobelts in an environmental transmission electron microscope (ETEM) in oxidizing, reducing and inert atmospheres while observing their structural changes with high spatial resolution. The interplay of surface reconstruction of high-energy surfaces of the wurtzite phase and environment-dependent anisotropic chemical etching of certain crystal surfaces in the branching mechanism of nanobelts has been observed. Understanding of structural and chemical transformations of materials via in situ microscopy techniques and their role in designingmore » new nanostructured materials is discussed.« less

  13. Real-time observation of morphological transformations in II-VI semiconducting nanobelts via environmental transmission electron microscopy

    SciTech Connect

    Agarwal, Rahul; Zakharov, Dmitri N.; Krook, Nadia M.; Liu, Wenjing; Berger, Jacob; Stach, Eric A.; Agarwal, Ritesh

    2015-05-01

    It has been observed that wurtzite II–VI semiconducting nanobelts transform into single-crystal, periodically branched nanostructures upon heating. The mechanism of this novel transformation has been elucidated by heating II–VI nanobelts in an environmental transmission electron microscope (ETEM) in oxidizing, reducing and inert atmospheres while observing their structural changes with high spatial resolution. The interplay of surface reconstruction of high-energy surfaces of the wurtzite phase and environment-dependent anisotropic chemical etching of certain crystal surfaces in the branching mechanism of nanobelts has been observed. Understanding of structural and chemical transformations of materials via in situ microscopy techniques and their role in designing new nanostructured materials is discussed.

  14. Synthesis of Cu0.95V2O5/polypyrrole core/sheath nanobelts and its electrochemical property

    NASA Astrophysics Data System (ADS)

    Zhang, Shaoyan; Han, Weirong; Chang, Yongfang; Sun, Yan; Li, Chunsheng

    2017-01-01

    A novel heterogeneous Cu0.95V2O5/polypyrrole core/sheath nanobelts have been synthesized via in-situ oxidative polymerization of pyrrole monomers on the surface of hydrothermally synthesized Cu0.95V2O5 nanobelts. The composite are several micrometers in length and 100-200 nm in width. The electrochemical performance of the composites for use as anode materials in lithium-ion batteries were investigated and compared with bare Cu0.95V2O5 nanobelts. It was found the electrochemical performance of Cu0.95V2O5/PPy was significantly enhanced. The remarkable electrochemical performance is mainly attributed to the heterogeneous core/sheath structure, the conductive PPy nanolayer coating help to preserve high capacity, maintain high electrochemical stability, and reduce charge transfer resistance during cycling performance.

  15. Hydrogenated TiO2 nanobelts as highly efficient photocatalytic organic dye degradation and hydrogen evolution photocatalyst.

    PubMed

    Tian, Jian; Leng, Yanhua; Cui, Hongzhi; Liu, Hong

    2015-12-15

    TiO2 nanobelts have gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Here we report the facile synthesis of hydrogenated TiO2 (H-TiO2) nanobelts, which exhibit excellent UV and visible photocatalytic decomposing of methyl orange (MO) and water splitting for hydrogen production. The improved photocatalytic property can be attributed to the Ti(3+) ions and oxygen vacancies in TiO2 nanobelts created by hydrogenation. Ti(3+) ions and oxygen vacancies can enhance visible light absorption, promote charge carrier trapping, and hinder the photogenerated electron-hole recombination. This work offers a simple strategy for the fabrication of a wide solar spectrum of active photocatalysts, which possesses significant potential for more efficient photodegradation, photocatalytic water splitting, and enhanced solar cells using sunlight as light source.

  16. Real-Time Observation of Morphological Transformations in II-VI Semiconducting Nanobelts via Environmental Transmission Electron Microscopy.

    PubMed

    Agarwal, Rahul; Zakharov, Dmitri N; Krook, Nadia M; Liu, Wenjing; Berger, Jacob S; Stach, Eric A; Agarwal, Ritesh

    2015-05-13

    It has been observed that wurtzite II-VI semiconducting nanobelts transform into single-crystal, periodically branched nanostructures upon heating. The mechanism of this novel transformation has been elucidated by heating II-VI nanobelts in an environmental transmission electron microscope (ETEM) in oxidizing, reducing, and inert atmospheres while observing their structural changes with high spatial resolution. The interplay of surface reconstruction of high-energy surfaces of the wurtzite phase and environment-dependent anisotropic chemical etching of certain crystal surfaces in the branching mechanism of nanobelts has been observed. Understanding of structural and chemical transformations of materials via in situ microscopy techniques and their role in designing new nanostructured materials is discussed.

  17. Ultrahigh quantum efficiency of CuO nanoparticle decorated In2Ge2O7 nanobelt deep-ultraviolet photodetectors

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Zhi, Chunyi; Zhai, Tianyou; Wang, Xi; Liao, Meiyong; Li, Songlin; Chen, Shimou; Golberg, Dmitri; Bando, Yoshio

    2012-09-01

    Although there has been significant progress in the fabrication and performance optimization of 1-D nanostructure-based deep-ultraviolet photodetectors, it is still a challenge to develop an effective device with high performance characteristics, such as high photocurrent-dark current ratio and high quantum efficiency. Herein, an efficient and simple method to fabricate high performance CuO nanoparticle decorated In2Ge2O7 nanobelt deep-ultraviolet photodetectors is presented. A CuO coated In2Ge2O7 nanobelt based photodetector showed very high responsivity (7.34 × 105 A W-1) and high quantum efficiency (3.5 × 106). The underlying mechanism is proposed to be the formation of p-n heterojunctions between decorated nanoparticles and nanobelts, which enhances the spatial separation of photogenerated electrons and holes. This study opens up a new horizon for creation of novel photodetectors with high quantum efficiency.Although there has been significant progress in the fabrication and performance optimization of 1-D nanostructure-based deep-ultraviolet photodetectors, it is still a challenge to develop an effective device with high performance characteristics, such as high photocurrent-dark current ratio and high quantum efficiency. Herein, an efficient and simple method to fabricate high performance CuO nanoparticle decorated In2Ge2O7 nanobelt deep-ultraviolet photodetectors is presented. A CuO coated In2Ge2O7 nanobelt based photodetector showed very high responsivity (7.34 × 105 A W-1) and high quantum efficiency (3.5 × 106). The underlying mechanism is proposed to be the formation of p-n heterojunctions between decorated nanoparticles and nanobelts, which enhances the spatial separation of photogenerated electrons and holes. This study opens up a new horizon for creation of novel photodetectors with high quantum efficiency. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31791e

  18. Electrospinning synthesis of InVO4/BiVO4 heterostructured nanobelts and their enhanced photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Liu, Zhendong; Lu, Qifang; Guo, Enyan; Liu, Suwen

    2016-08-01

    In the present work, one-dimensional InVO4/BiVO4 heterostructured nanobelts with the width of about 800 nm have been successfully prepared by a simple electrospinning technique followed by the subsequent calcination process. The prepared products were characterized by thermogravimetry, fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-Vis absorbance spectroscopy, high-performance liquid chromatography, and photoluminescence spectroscopy. The obtained InVO4/BiVO4 heterostructured nanobelts presented an admirable morphology and excellent photocatalytic properties for the degradation of methylene blue solution under visible-light irradiation.

  19. Synthesis of Peptide-Based Hybrid Nanobelts with Enhanced Color Emission by Heat Treatment or Water Induction.

    PubMed

    Liu, Xingcen; Zhu, Pengli; Fei, Jinbo; Zhao, Jie; Yan, Xuehai; Li, Junbai

    2015-06-22

    We demonstrate that an inorganic lanthanide ion (Tb(3+)) or organic dye molecules were encapsulated in situ into diphenylalanine (FF) organogels by a general, simple, and efficient co-assembly process, which generated peptide-based hybrid nanobelts with a range of colored emissions. In the presence of a photosensitizer (salicylic acid), the organogel can serve as an excellent molecular-donor scaffold to investigate FRET to Tb(3+). More importantly, heat treatment or water induction instigated a morphology transition from nanofibers to nanobelts, after which the participation of guest molecules in the FF assembly was promoted and the stability and photoluminescence emission of the composite organogels were enhanced.

  20. Hysteresis-free high-temperature precise bimorph actuators produced by direct bonding of lithium niobate wafers

    SciTech Connect

    Shur, V. Ya.; Baturin, I. S.; Mingaliev, E. A.; Zorikhin, D. V.; Udalov, A. R.; Greshnyakov, E. D.

    2015-02-02

    The current paper presents a piezoelectric bimorph actuator produced by direct bonding of lithium niobate wafers with the mirrored Y and Z axes. Direct bonding technology allowed to fabricate bidomain plate with precise positioning of ideally flat domain boundary. By optimizing the cutting angle (128° Y-cut), the piezoelectric constant became as large as 27.3 pC/N. Investigation of voltage dependence of bending displacement confirmed that bimorph actuator has excellent linearity and hysteresis-free. Decrease of the applied voltage down to mV range showed the perfect linearity up to the sub-nm deflection amplitude. The frequency and temperature dependences of electromechanical transmission coefficient in wide temperature range (from 300 to 900 K) were investigated.

  1. Hysteresis-free high-temperature precise bimorph actuators produced by direct bonding of lithium niobate wafers

    NASA Astrophysics Data System (ADS)

    Shur, V. Ya.; Baturin, I. S.; Mingaliev, E. A.; Zorikhin, D. V.; Udalov, A. R.; Greshnyakov, E. D.

    2015-02-01

    The current paper presents a piezoelectric bimorph actuator produced by direct bonding of lithium niobate wafers with the mirrored Y and Z axes. Direct bonding technology allowed to fabricate bidomain plate with precise positioning of ideally flat domain boundary. By optimizing the cutting angle (128° Y-cut), the piezoelectric constant became as large as 27.3 pC/N. Investigation of voltage dependence of bending displacement confirmed that bimorph actuator has excellent linearity and hysteresis-free. Decrease of the applied voltage down to mV range showed the perfect linearity up to the sub-nm deflection amplitude. The frequency and temperature dependences of electromechanical transmission coefficient in wide temperature range (from 300 to 900 K) were investigated.

  2. Piezoelectric bimorph-based scanner in the tip-scan mode for high speed atomic force microscope.

    PubMed

    Zhao, Jianyong; Gong, Weitao; Cai, Wei; Shang, Guangyi

    2013-08-01

    A piezoelectric bimorph-based scanner operating in tip-scan mode for high speed atomic force microscope (AFM) is first presented. The free end of the bimorph is used for fixing an AFM cantilever probe and the other one is mounted on the AFM head. The sample is placed on the top of a piezoelectric tube scanner. High speed scan is performed with the bimorph that vibrates at the resonant frequency, while slow scanning is carried out by the tube scanner. The design and performance of the scanner is discussed and given in detailed. Combined with a commercially available data acquisition system, a high speed AFM has been built successfully. By real-time observing the deformation of the pores on the surface of a commercial piezoelectric lead zirconate titanate (PZT-5) ceramics under electric field, the dynamic imaging capability of the AFM is demonstrated. The results show that the notable advantage of the AFM is that dynamic process of the sample with large dimensions can be easily investigated. In addition, this design could provide a way to study a sample in real time under the given experimental condition, such as under an external electric field, on a heating stage, or in a liquid cell.

  3. Photocatalytic CO2 Reduction by Carbon-Coated Indium-Oxide Nanobelts.

    PubMed

    Pan, Yun-Xiang; You, Ya; Xin, Sen; Li, Yutao; Fu, Gengtao; Cui, Zhiming; Men, Yu-Long; Cao, Fei-Fei; Yu, Shu-Hong; Goodenough, John B

    2017-03-22

    Indium-oxide (In2O3) nanobelts coated by a 5-nm-thick carbon layer provide an enhanced photocatalytic reduction of CO2 to CO and CH4, yielding CO and CH4 evolution rates of 126.6 and 27.9 μmol h(-1), respectively, with water as reductant and Pt as co-catalyst. The carbon coat promotes the absorption of visible light, improves the separation of photoinduced electron-hole pairs, increases the chemisorption of CO2, makes more protons from water splitting participate in CO2 reduction, and thereby facilitates the photocatalytic reduction of CO2 to CO and CH4.

  4. Synthesis of Tapered CdS Nanobelts and CdSe Nanowires with Good Optical Property by Hydrogen-Assisted Thermal Evaporation.

    PubMed

    Wang, Min; Fei, Guangtao

    2009-07-10

    The tapered CdS nanobelts and CdSe nanowires were prepared by hydrogen-assisted thermal evaporation method. Different supersaturation leads to two different kinds of 1D nanostructures. The PL measurements recorded from the as-prepared tapered CdS nanobelts and CdSe nanowires show only a bandgap emission with relatively narrow full-width half maximum, which means that they possess good optical property. The as-synthesized high-quality tapered CdS nanobelts and CdSe nanowires may be excellent building blocks for photonic devices.

  5. Anatase TiO2 ultrathin nanobelts derived from room-temperature-synthesized titanates for fast and safe lithium storage

    PubMed Central

    Wen, Wei; Wu, Jin-ming; Jiang, Yin-zhu; Yu, Sheng-lan; Bai, Jun-qiang; Cao, Min-hua; Cui, Jie

    2015-01-01

    Lithium-ion batteries (LIBs) are promising energy storage devices for portable electronics, electric vehicles, and power-grid applications. It is highly desirable yet challenging to develop a simple and scalable method for constructions of sustainable materials for fast and safe LIBs. Herein, we exploit a novel and scalable route to synthesize ultrathin nanobelts of anatase TiO2, which is resource abundant and is eligible for safe anodes in LIBs. The achieved ultrathin nanobelts demonstrate outstanding performances for lithium storage because of the unique nanoarchitecture and appropriate composition. Unlike conventional alkali-hydrothermal approaches to hydrogen titanates, the present room temperature alkaline-free wet chemistry strategy guarantees the ultrathin thickness for the resultant titanate nanobelts. The anatase TiO2 ultrathin nanobelts were achieved simply by a subsequent calcination in air. The synthesis route is convenient for metal decoration and also for fabricating thin films of one/three dimensional arrays on various substrates at low temperatures, in absence of any seed layers. PMID:26133276

  6. A New Device for Bimorph Mirrors Technology: the A1902BS Bipolar Power Supply System

    NASA Astrophysics Data System (ADS)

    Cautero, M.; Cautero, G.; Krastanov, B.; Billè, F.; Borghes, R.; Iviani, L.; Cocco, D.; Sostero, G.; Signorato, R.

    2007-01-01

    An important feature of X-ray Piezoelectric Bimorph Mirror (PBM) is the possibility to continuously vary its curvature (dynamical bending); this ability allows the precise adjustment of their optical properties to different beamline geometries and permits the variation of the grazing angle of incidence or to optimize the focal spot dimensions in the experimental chamber. When a driving voltage is applied at a particular position of the mirror, one of the piezo plates shrinks while the other one expands and, as an example, it can result in a purely spherical bending of the device if the same voltage is applied to all electrodes. The applied voltages have to be kept extremely stable on a very long time scale (weeks or even months). This means that the performance and the general behavior of the mirror are strongly dependent on the power supply used to drive it. For this challenging application, Sincrotrone Trieste developed a particularly stable high voltage bipolar power supply system (ranging from -2kV to + 2kV, zero crossing). This system is controlled by an Intel SBC board and accessible via Ethernet through any common web browser, Lab VIEW client or some of the most popular synchrotron facility control systems (Epics and Tango for instance). The maximum drain and source capabilities are 500uA per channel. Voltage monitoring is achieved by sensing the real output and feeding it to a true 16bit ADC. The voltage resolution achieved is about 60mV while the current resolution is about 60nA. Noise and residual ripple (rms) are better than 15ppm/FS and, most important, the long term stability (1 week observation) is better than 100ppm/FS. Some metrological measurements, on different bimorph mirrors, was carried out at the optical laboratory of Elettra. These measures demonstrate the high level of resolution and stability of the power supplies, able to change considerably the radius of curvature of the mirror and, in the meantime, correct even very small shape error.

  7. Micromachining of a bimorph Pb(Zr,Ti)O3 (PZT) cantilever using a micro-electromechanical systems (MEMS) process for energy harvesting application.

    PubMed

    Kim, Moonkeun; Hwang, Beomseok; Jeong, Jaehwa; Min, Nam Ki; Kwon, Kwang-Ho

    2012-07-01

    We designed and fabricated a bimorph Pb(Zr,Ti)O3 (PZT) cantilever with an integrated Si proof mass to obtain a low resonant frequency for an energy harvesting application. The cantilevers were fabricated on the micro-electromechanical systems (MEMS) scale. A mode of piezoelectric conversions were d31 and d33 mode in cantilever vibration Therefore, we designed and fabricated a single cantilever with d31 unimorph, d31 bimorph, d33 unimorph, and d33 bimorph modes. Finally, we fabricated a device with beam dimensions of about 5,400 microm x 480 microm x 14 microm (< +/- 5%), and an integrated Si proof mass with dimensions of about 1,481 microm x 988 microm x 450 microm (< +/- 5%). In order to measure the d31 and d33 modes, we fabricated top and bottom electrodes. The distance between the top electrodes was 50 microm and the resonant frequency was 89.4 Hz. The average powers of the d31 unimorph, d31 bimorph, d33 unimorph, and d33 bimorph modes were 3.90, 9.60, 21.42, and 22.47 nW at 0.8 g (g = 9.8 m/s2) and optimal resistance, respectively.

  8. A Single Nanobelt Transistor for Gas Identification: Using a Gas-Dielectric Strategy.

    PubMed

    Cai, Bin; Song, Zhiqi; Tong, Yanhong; Tang, Qingxin; Shaymurat, Talgar; Liu, Yichun

    2016-06-21

    Despite tremendous potential and urgent demand in high-response low-cost gas identification, the development of gas identification based on a metal oxide semiconductor nanowire/nanobelt remains limited by fabrication complexity and redundant signals. Researchers have shown a multisensor-array strategy with "one key to one lock" configuration. Here, we describe a new strategy to create high-response room-temperature gas identification by employing gas as dielectric. This enables gas discrimination down to the part per billion (ppb) level only based on one pristine single nanobelt transistor, with the excellent average Mahalanobis distance (MD) as high as 35 at the linear discriminant analysis (LDA) space. The single device realizes the selective recognition function of electronic nose. The effect of the gas dielectric on the response of the multiple field-effect parameters is discussed by the comparative investigation of gas and solid-dielectric devices and the studies on trap density changes in the conductive channel. The current work opens up exciting opportunities for room-temperature gas recognition based on the pristine single device.

  9. A Single Nanobelt Transistor for Gas Identification: Using a Gas-Dielectric Strategy

    PubMed Central

    Cai, Bin; Song, Zhiqi; Tong, Yanhong; Tang, Qingxin; Shaymurat, Talgar; Liu, Yichun

    2016-01-01

    Despite tremendous potential and urgent demand in high-response low-cost gas identification, the development of gas identification based on a metal oxide semiconductor nanowire/nanobelt remains limited by fabrication complexity and redundant signals. Researchers have shown a multisensor-array strategy with “one key to one lock” configuration. Here, we describe a new strategy to create high-response room-temperature gas identification by employing gas as dielectric. This enables gas discrimination down to the part per billion (ppb) level only based on one pristine single nanobelt transistor, with the excellent average Mahalanobis distance (MD) as high as 35 at the linear discriminant analysis (LDA) space. The single device realizes the selective recognition function of electronic nose. The effect of the gas dielectric on the response of the multiple field-effect parameters is discussed by the comparative investigation of gas and solid-dielectric devices and the studies on trap density changes in the conductive channel. The current work opens up exciting opportunities for room-temperature gas recognition based on the pristine single device. PMID:27338394

  10. Ultrafast spatially-resolved carrier dynamics in single CdSSe nanobelts

    NASA Astrophysics Data System (ADS)

    Gundlach, Lars; Piotrowiak, Piotr

    2009-03-01

    A recently constructed Kerr-gated microscope was applied to spatially, temporally, and spectrally resolve the ultrafast non-linear excitation relaxation dynamics in single CdSSe nanobelts. Luminescence movies with a 100 fs frame resolution were constructed. The ability to spatially resolve the femtosecond dynamics in a single emitting object gives insights which would be impossible to obtain in an ensemble measurement. By applying the Kerr-gated microscope we are able to monitor the dynamics in a single nanobelt with a sufficient time resolution to reveal the different pathways that compete with the dissociation of multiple excitons. We will show that ensemble averaging methods give results that are complicated because of ensemble inhomogeneities. Indeed, already a different orientation of the nanoparticles with respect to the light-field leads to different dynamic response and difficult to interpret results. The onset of nonlinear behavior and the subsequent dynamics are particularly sensitive to even the most subtle inhomogeneities in composition and morphology and hence most difficult to study under the condition of ensemble averaging making time-resolved wide-field fluorescence microscopy a perfect aid in disentangling the complex response.

  11. Local defect-induced red-shift of cathodoluminescence in individual ZnS nanobelts.

    PubMed

    Liu, B D; Yang, B; Dierre, B; Sekiguchi, T; Jiang, X

    2014-11-07

    The luminescence of semiconductor nanostructures is strongly dependent on their size, dimensions, morphology, composition, or defects, and their band emissions can be properly and selectively tailored through the rational manipulation of these parameters during material growth. Using spatially-resolved cathodoluminescence spectroscopy, monochromatic contrast maps and high-resolution transmission electron microscopy, an obvious red-shift of the near-band-edge emission of wurtzite ZnS nanobelts, resulting from a strip of stacking faults or a zinc-blende phase with tens of atomic layers in width, has been observed and its related mechanism has been discussed. This finding is not specific to the defect-dependent optical properties tailoring of ZnS nanostructures and represents a general validity for clarifying the mechanism of peak-shift (band-gap expansion or shrinking) of a wide range of semiconductor nanostructures with various defects. In addition, the general formation mechanism of the belt-like nanostructure was proposed based on precise microstructure analyses on a ZnS nanobelt with atomic terrace growth fronts.

  12. Ti(3+)-Promoted High Oxygen-Reduction Activity of Pd Nanodots Supported by Black Titania Nanobelts.

    PubMed

    Yuan, Xiaotao; Wang, Xin; Liu, Xiangye; Ge, Hongxin; Yin, Guoheng; Dong, Chenlong; Huang, Fuqiang

    2016-10-04

    One-dimensional nanocrystals favoring efficient charge transfer have attracted enormous attentions, and conductive nanobelts of black titania with a unique band structure and high electrical conductivity would be interestingly used in electrocatalysis. Here, Pd nanodots supported by two kinds of black titania, the oxygen-deficient titania (TiO2-x) and nitrogen-doped titania (TiO2-x:N), were synthesized as efficient composite catalysts for oxygen-reduction reaction (ORR). These composite catalysts show improved catalytic activity with lower overpotential and higher limited current, compared to the Pd nanodots supported on the white titania (Pd/TiO2). The improved activity is attributed to the relatively high conductivity of black titania nanobelts for efficient charge transfer (CT) between Ti(3+) species and Pd nanodots. The CT process enhances the strong metal-support interaction (SMSI) between Pd and TiO2, which lowers the absorption energy of O2 on Pd and makes it more suitable for oxygen reduction. Because of the stronger interaction between Pd and support, the Pd/TiO2-x:N also shows excellent durability and immunity to methanol poisoning.

  13. Characterization of a bimorph deformable mirror using stroboscopic phase-shifting interferometry

    PubMed Central

    Horsley, David A.; Park, Hyunkyu; Laut, Sophie P.; Werner, John S.

    2008-01-01

    The static and dynamic characteristics of a bimorph deformable mirror (DM) for use in an adaptive optics system are described. The DM is a 35-actuator device composed of two disks of lead magnesium niobate (PMN), an electrostrictive ceramic that produces a mechanical strain in response to an imposed electric field. A custom stroboscopic phase-shifting interferometer was developed to measure the deformation of the mirror in response to applied voltage. The ability of the mirror to replicate optical aberrations described by the Zernike polynomials was tested as a measure of the mirror’s static performance. The natural frequencies of the DM were measured up to 20 kHz using both stroboscopic interferometry as well as a commercial laser Doppler vibrometer (LDV). Interferometric measurements of the DM surface profile were analyzed by fitting the surface with mode-shapes predicted using classical plate theory for an elastically supported disk. The measured natural frequencies were found to be in good agreement with the predictions of the theoretical model. PMID:19122798

  14. Development of in-series piezoelectric bimorph bending beam actuators for active flow control applications

    NASA Astrophysics Data System (ADS)

    Chan, Wilfred K.; Clingman, Dan J.; Amitay, Michael

    2016-04-01

    Piezoelectric materials have long been used for active flow control purposes in aerospace applications to increase the effectiveness of aerodynamic surfaces on aircraft, wind turbines, and more. Piezoelectric actuators are an appropriate choice due to their low mass, small dimensions, simplistic design, and frequency response. This investigation involves the development of piezoceramic-based actuators with two bimorphs placed in series. Here, the main desired characteristic was the achievable displacement amplitude at specific driving voltages and frequencies. A parametric study was performed, in which actuators with varying dimensions were fabricated and tested. These devices were actuated with a sinusoidal waveform, resulting in an oscillating platform on which to mount active flow control devices, such as dynamic vortex generators. The main quantification method consisted of driving these devices with different voltages and frequencies to determine their free displacement, blocking force, and frequency response. It was found that resonance frequency increased with shorter and thicker actuators, while free displacement increased with longer and thinner actuators. Integration of the devices into active flow control test modules is noted. In addition to physical testing, a quasi-static analytical model was developed and compared with experimental data, which showed close correlation for both free displacement and blocking force.

  15. Experimental validation of a distributed parameter piezoelectric bimorph cantilever energy harvester

    NASA Astrophysics Data System (ADS)

    Rafique, S.; Bonello, P.

    2010-09-01

    Recent rapid advances in low-power portable electronic applications have motivated researchers and industry to explore schemes to embed an endless power supply mechanism within these systems. These self-charging embedded power supply systems convert ambient energy (vibration, solar, wind, etc) into electrical energy and subsequently provide power to these portable applications. Ambient vibration is one of the most promising sources of energy as it is abundantly present in indoor/outdoor systems. This paper discusses briefly the mathematical model of a bimorph piezoelectric cantilever beam with distributed inertia, and its experimental validation. Research on such a component typically included a tip mass, which reduced the influence of the distributed inertia of the beam and restricted effective operation to low frequencies. The present work excludes the tip mass and only the distributed mass of the harvester is considered. Due to the coupled electromechanical nature of piezoelectric materials, the effects of electrical coupling on the mechanical properties of the harvester are investigated, particularly the dependence of the induced additional stiffness and damping on the electrical load. Both the model and the experimental results show that the resonance frequency and the response amplitude of the harvester exhibit considerable shifts due to the electrical coupling. The experimental work uses both magnitude and Nyquist plots of the electromechanical frequency response functions to thoroughly validate the accuracy and applicability of the distributed parameter model at higher frequencies than previously considered.

  16. Dispersive suspended microextraction.

    PubMed

    Yang, Zhong-Hua; Liu, Yu; Lu, Yue-Le; Wu, Tong; Zhou, Zhi-Qiang; Liu, Dong-Hui

    2011-11-14

    A novel sample pre-treatment technique termed dispersive suspended microextraction (DSME) coupled with gas chromatography-flame photometric detection (GC-FPD) has been developed for the determination of eight organophosphorus pesticides (ethoprophos, malathion, chlorpyrifos, isocarbophos, methidathion, fenamiphos, profenofos, triazophos) in aqueous samples. In this method, both extraction and two phases' separation process were performed by the assistance of magnetic stirring. After separating the two phases, 1 μL of the suspended phase was injected into GC for further instrument analysis. Varieties of experiment factors which could affect the experiment results were optimized and the following were selected: 12.0 μL p-xylene was selected as extraction solvent, extraction speed was 1200 rpm, extraction time was 30 s, the restoration speed was 800 rpm, the restoration time was 8 min, and no salt was added. Under the optimum conditions, limits of detections (LODs) varied between 0.01 and 0.05 μg L(-1). The relative standard deviation (RSDs, n=6) ranged from 4.6% to 12.1%. The linearity was obtained by five points in the concentration range of 0.1-100.0 μg L(-1). Correlation coefficients (r) varied from 0.9964 to 0.9995. The enrichment factors (EFs) were between 206 and 243. In the final experiment, the developed method has been successfully applied to the determination of organophosphorus pesticides in wine and tap water samples and the obtained recoveries were between 83.8% and 101.3%. Compared with other pre-treatment methods, DSME has its own features and could achieve satisfied results for the analysis of trace components in complicated matrices.

  17. Large electrical manipulation of permittivity in BaTiO{sub 3} and Pb(Zr,Ti)O{sub 3} bimorph heterostructure

    SciTech Connect

    Ci, Penghong; Liu, Guoxi; Dong, Shuxiang; Zhang, Li

    2014-08-18

    We report a strain-mediated electric field manipulation of permittivity in BaTiO{sub 3} (barium titanate, BT) ceramic by a Pb(Zr,Ti)O{sub 3} (PZT) bimorph. This BT/PZT heterostructure exhibited a relatively large permittivity tunability of BT up to ±10% in a wide frequency range under an electric field of ±4 kV/cm applied to the PZT bimorph. The permittivity tunability is attributed to the strain in BT produced by the PZT bimorph. Calculations of the relationship between permittivity and applied electric field were developed, and corresponded well with measurements. The BT/PZT heterostructure has potential for applications in broadband field tunable smart electronic devices.

  18. Suspended-sediment transport measurement

    USGS Publications Warehouse

    Gray, John R.

    2007-01-01

    Of the two operationally defined phases of fluvial-sediment transport – suspended load and bedload – collection of suspended-load data is the more common. This is a reflection of a number of factors including the general predominance of suspended load over bedload in mass transport and the greater difficulty and costs associated with collecting bedload data. Acquisition of suspended-sediment data for sediment-transport computations requires collection of water-sediment samples that represent, or can be reliably adjusted to represent, the mean discharge-weighted concentration and particle-size distribution in a cross section at the time of sample collection. Analytical results from a sufficient number of representative samples obtained with concurrent water-discharge values are needed to compute suspended-sediment discharge for the period of interest.

  19. Suspended graphene variable capacitor

    NASA Astrophysics Data System (ADS)

    AbdelGhany, M.; Mahvash, F.; Mukhopadhyay, M.; Favron, A.; Martel, R.; Siaj, M.; Szkopek, T.

    2016-12-01

    Electromechanical variable capacitors, or varactors, find a wide range of applications including sensing applications and the tuning of electrical circuit resonance. We demonstrate a nano-electromechanical graphene varactor, a variable capacitor wherein the capacitance is tuned by voltage controlled deflection of a dense array of suspended graphene membranes. The low flexural rigidity of graphene monolayers is exploited to achieve low actuation voltage and high tunable capacitance density in an ultra-thin structure. Large arrays comprising thousands of suspensions were fabricated to give a tunable capacitance of over 10 pF mm-2. This capacitance density suggests that graphene offers a potential solution to the challenge of reducing the size of micro-electromechanical systems (MEMS). A capacitance tuning of 55% was achieved with a 10 V actuating voltage, exceeding the 50% tuning limit of Hookean parallel plate pull-in without the use of complex mechanical schemes that occupy substrate area. Capacitor behavior was investigated experimentally, and described by a simple theoretical model. Mechanical properties of the graphene membranes were measured independently using atomic force microscopy. We present a comparison of state-of-the-art MEMS and graphene varactors. The quality factor of graphene varactors is limited by graphene sheet resistance, pull-in voltage can be improved with more aggressive scaling, while the power handling and cycling stability of graphene varactors remains unknown.

  20. Self-assembly of ultrathin Cu2MoS4 nanobelts for highly efficient visible light-driven degradation of methyl orange

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Chen, Wenxing; Lin, Yunxiang; Chen, Haiping; Haleem, Yasir A.; Wu, Chuanqiang; Ye, Fei; Wang, Tianxing; Song, Li

    2015-10-01

    We demonstrate ultrathin self-assembled Cu2MoS4 nanobelts synthesized by using Cu2O as the starting sacrificial template via a hydrothermal method. The nanobelts exhibit strong light absorption over a broad wavelength spectrum, suggesting their potential application as photocatalysts. The photocatalytic activity of nanobelts is evaluated by the degradation of Methyl Orange (MO) dye under visible light irradiation. Notably, the nanobelts can completely degrade 100 mL of 15 mg mL-1 MO in 20 minutes with excellent recycling and structural stability, suggesting their excellent photocatalytic performance. In comparison with a sheet-like sample, the high efficiency of the self-assembled Cu2MoS4 nanobelts is attributed to a high surface area and a unique band gap, agreeing with the nitrogen adsorption analysis and photoluminescence spectra. This study offers a self-assembled synthetic route to create new multifunctional nanoarchitectures composed of atomic layers, and thus may open a window for greatly extending potential applications in water pollution treatment, photocatalytic water-splitting, solar cells and other related fields.We demonstrate ultrathin self-assembled Cu2MoS4 nanobelts synthesized by using Cu2O as the starting sacrificial template via a hydrothermal method. The nanobelts exhibit strong light absorption over a broad wavelength spectrum, suggesting their potential application as photocatalysts. The photocatalytic activity of nanobelts is evaluated by the degradation of Methyl Orange (MO) dye under visible light irradiation. Notably, the nanobelts can completely degrade 100 mL of 15 mg mL-1 MO in 20 minutes with excellent recycling and structural stability, suggesting their excellent photocatalytic performance. In comparison with a sheet-like sample, the high efficiency of the self-assembled Cu2MoS4 nanobelts is attributed to a high surface area and a unique band gap, agreeing with the nitrogen adsorption analysis and photoluminescence spectra. This study

  1. A soft-polymer piezoelectric bimorph cantilever-actuated peristaltic micropump.

    PubMed

    Graf, Neil J; Bowser, Michael T

    2008-10-01

    A peristaltic micropump was fabricated and characterized. The micropump was fabricated using soft lithography, and actuated using piezoelectric bimorph cantilevers. The micropump channel was formed by bonding two layers of PDMS, mixed at 5:1 and 30:1 ratios. The channel was fabricated in the 5:1 layer using replica molding (REM), where a very simple and inexpensive template was made by straddling a 75 microm wire over a glass substrate, followed by covering and smoothing over the wire with a piece of aluminium foil. Not only was this template inexpensive and extremely simple to fabricate, it also created a rounded cross-sectional geometry which is favorable for complete valve shutoff. The cantilevers were driven at Vp=+/-90 V with amplified square wave signals generated by a virtual function generator created in LabVIEW. Connections to the micropump were made by placing capillary tubes in the channel, and then sealed between the two layers of PDMS. Machined aluminium clamps were adhered to the tips of the cantilevers with general purpose adhesive. These clamps allowed for aluminium valves, with finely machined tips of dimensions 3 mm by 200 microm, to be held firmly in place. The variables characterized for this micropump were flow rate, maximum attainable backpressure, free cantilever deflection, valve shutoff, and valve leakage. Three actuation patterns with phase differences of 60, 90, and 120 degrees were compared for flow rate and maximum backpressure. It was determined that the 120 degrees signal outperformed the 60 degrees and 90 degrees signals for both maximum flowrate and maximum attainable backpressure. The maximum and minimum flowrates demonstrated by the micropump were 289 nL min(-1) and 53 nL min(-1), respectively. The maximum backpressure attained was 35 300 Pa. It was also demonstrated that the valves fully closed the channels upon actuation, with minimal observed leakage.

  2. Electroelastic modeling and experimental validations of piezoelectric energy harvesting from broadband random vibrations of cantilevered bimorphs

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Erturk, A.

    2013-01-01

    We present electroelastic modeling, analytical and numerical solutions, and experimental validations of piezoelectric energy harvesting from broadband random vibrations. The modeling approach employed herein is based on a distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included, since broadband random vibrations, such as Gaussian white noise, might excite higher vibration modes. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given power spectral density (PSD) or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first of the two numerical solution methods employs the Fourier series representation of the base acceleration history in an ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H bimorph under different random excitation levels. The simulations exhibit very good agreement with the experimental measurements for a range of resistive electrical boundary conditions and input PSD levels. It is also shown that lightly damped higher vibration modes can alter the expected power curve under broadband random excitation. Therefore, the distributed-parameter modeling and solutions presented herein can be used as a more accurate alternative to the existing single-degree-of-freedom solutions for broadband random vibration energy harvesting.

  3. Present perspectives of broadband photodetectors based on nanobelts, nanoribbons, nanosheets and the emerging 2D materials

    NASA Astrophysics Data System (ADS)

    Dhanabalan, Sathish Chander; Ponraj, Joice Sophia; Zhang, Han; Bao, Qiaoliang

    2016-03-01

    Recent research on photodetectors has been mainly focused on nanostructured materials that form the building blocks of device fabrication. The selection of a suitable material with well-defined properties forms the key issue for the fabrication of photodetectors that cover different ranges of the electromagnetic spectrum. In this review, the latest progress in light detection using nanobelts, nanoribbons, nanosheets and the emerging two-dimensional (2D) materials is reviewed. Particular emphasis is placed on the detection of light by the hybrid structures of the mentioned nanostructured materials in order to enhance the efficiency of the light-matter interaction. The booming research area of black phosphorus based photo-detection is also reviewed. This review provides an overview of basic concepts and new directions towards photodetectors, and highlights potential for the future development of high performance broadband photodetectors.

  4. Nanotubes, nanobelts, nanowires, and nanorods of silicon carbide from the wheat husks

    SciTech Connect

    Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Feng, J.; Qadri, S. N.; Caldwell, J. D.

    2015-09-14

    Nanotubes, nanowires, nanobelts, and nanorods of SiC were synthesized from the thermal treatment of wheat husks at temperatures in excess of 1450 °C. From the analysis based on x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, it has been found that the processed samples of wheat husk consisted of 2H and 3C polytypes of SiC exhibiting the nanostructure shapes. These nanostructures of silicon carbide formed from wheat husks are of technological importance for designing advance composites, applications in biotechnology, and electro-optics. The thermodynamics of the formation of SiC is discussed in terms of the rapid solid state reaction between hydrocarbons and silica on the molecular scale, which is inherently present in the wheat husks.

  5. Electrochemical sensing of bisphenol using a multilayer graphene nanobelt modified photolithography patterned platinum electrode

    NASA Astrophysics Data System (ADS)

    Karthick Kannan, Padmanathan; Hu, Chunxiao; Morgan, Hywel; Moshkalev, Stanislav A.; Sekhar Rout, Chandra

    2016-09-01

    An electrochemical sensor has been developed for the detection of Bisphenol-A (BPA) using photolithographically patterned platinum electrodes modified with multilayer graphene nanobelts (GNB). Compared to bare electrodes, the GNB modified electrode exhibited enhanced BPA oxidation current, due to the high effective surface area and high adsorption capacity of the GNB. The sensor showed a linear response over the concentration range from 0.5 μM-9 μM with a very low limit of detection = 37.33 nM. In addition, the sensor showed very good stability and reproducibility with good specificity, demonstrating that GNB is potentially a new material for the development of a practical BPA electrochemical sensor with application in both industrial and plastic industries.

  6. Present perspectives of broadband photodetectors based on nanobelts, nanoribbons, nanosheets and the emerging 2D materials.

    PubMed

    Dhanabalan, Sathish Chander; Ponraj, Joice Sophia; Zhang, Han; Bao, Qiaoliang

    2016-03-28

    Recent research on photodetectors has been mainly focused on nanostructured materials that form the building blocks of device fabrication. The selection of a suitable material with well-defined properties forms the key issue for the fabrication of photodetectors that cover different ranges of the electromagnetic spectrum. In this review, the latest progress in light detection using nanobelts, nanoribbons, nanosheets and the emerging two-dimensional (2D) materials is reviewed. Particular emphasis is placed on the detection of light by the hybrid structures of the mentioned nanostructured materials in order to enhance the efficiency of the light-matter interaction. The booming research area of black phosphorus based photo-detection is also reviewed. This review provides an overview of basic concepts and new directions towards photodetectors, and highlights potential for the future development of high performance broadband photodetectors.

  7. Enhancing the electrical and optoelectronic performance of nanobelt devices by molecular surface functionalization.

    PubMed

    Lao, Changshi; Li, Yi; Wong, C P; Wang, Z L

    2007-05-01

    By functionalizing the surfaces of ZnO nanobelts (NBs) with a thin self-assembled molecular layer, the electrical and optoelectronic performances of a single NB-based device are drastically improved. For a single NB-based device, due to energy band tuning and surface modification, the conductance was enhanced by 6 orders of magnitude upon functionalization; a coating molecule layer has changed a Schottky contact into an Ohmic contact without sophisticated deposition of multilayered metals. A functionalized NB showed negative differential resistance and exhibited huge improved photoconductivity and gas sensing response. The functionalized molecular layer also greatly reduced the etching rate of the ZnO NBs by buffer solution, largely extending their life time for biomedical applications. Our study demonstrates a new approach for improving the physical properties of oxide NBs and nanowires for device applications.

  8. Nanotubes, nanobelts, nanowires, and nanorods of silicon carbide from the wheat husks

    NASA Astrophysics Data System (ADS)

    Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Feng, J.; Qadri, S. N.; Caldwell, J. D.

    2015-09-01

    Nanotubes, nanowires, nanobelts, and nanorods of SiC were synthesized from the thermal treatment of wheat husks at temperatures in excess of 1450 °C. From the analysis based on x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, it has been found that the processed samples of wheat husk consisted of 2H and 3C polytypes of SiC exhibiting the nanostructure shapes. These nanostructures of silicon carbide formed from wheat husks are of technological importance for designing advance composites, applications in biotechnology, and electro-optics. The thermodynamics of the formation of SiC is discussed in terms of the rapid solid state reaction between hydrocarbons and silica on the molecular scale, which is inherently present in the wheat husks.

  9. Highly sensitive and selective electrochemical dopamine sensing properties of multilayer graphene nanobelts

    NASA Astrophysics Data System (ADS)

    Karthick Kannan, Padmanathan; Moshkalev, Stanislav A.; Sekhar Rout, Chandra

    2016-02-01

    In the present study, we report the electrochemical sensing property of multi-layer graphene nanobelts (GNBs) towards dopamine (DA). GNBs are synthesized from natural graphite and characterized by using techniques like field-emission scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An electrochemical sensor based on GNBs is developed for the detection of DA. From the cyclic voltammetry and amperometry studies, it is found that GNBs possess excellent electrocatalytic activity towards DA molecules. The developed DA sensor showed a sensitivity value of 0.95 μA μM-1 cm-2 with a linear range of 2 μM to 0.2 mM. The interference data exhibited that GNB is highly selective to DA even in the presence of common interfering species like ascorbic acid, uric acid, glucose and lactic acid.

  10. Differential mouse pulmonary dose and time course responses to titanium dioxide nanospheres and nanobelts.

    PubMed

    Porter, Dale W; Wu, Nianqiang; Hubbs, Ann F; Mercer, Robert R; Funk, Kathleen; Meng, Fanke; Li, Jiangtian; Wolfarth, Michael G; Battelli, Lori; Friend, Sherri; Andrew, Michael; Hamilton, Raymond; Sriram, Krishnan; Yang, Feng; Castranova, Vincent; Holian, Andrij

    2013-01-01

    Three anatase titanium dioxide (TiO(2)) nanoparticles (NPs) were prepared; nanospheres (NSs), short nanobelts (NB1), and long nanobelts (NB2). These NPs were used to investigate the effect of NP shape and length on lung toxicity. Mice were exposed (0-30 µg per mouse) by pharyngeal aspiration and pulmonary toxicity was assessed over a 112-day time course. Whole lung lavage data indicated that NB1- and NB2-exposed mice, but not NS-exposed mice, had significant dose- and time-dependent pulmonary inflammation and damage. Histopathological analyses at 112 days postexposure determined no interstitial fibrosis in any NS-exposed mice, an increased incidence in 30 µg NB1-exposed mice, and significant interstitial fibrosis in 30 µg NB2-exposed mice. At 112 days postexposure, lung burden of NS was decreased by 96.4% and NB2 by 80.5% from initial deposition levels. At 112 days postexposure, enhanced dark field microscopy determined that alveolar macro- phages were the dominant deposition site, but a fraction of NB1 and NB2 was observed in the alveolar interstitial spaces. For the 30 µg exposure groups at 112 days postexposure, confocal micro- scopy and immunofluorescent staining demonstrated that retained NB2 but not NS were present in the interstitium subjacent to the terminal bronchiole near the normal location of the smallest lymphatic capillaries in the lung. These lymphatic capillaries play a critical role in particle clearance, and the accumulation of NB2, but not NS, suggests possible impaired lymphatic clearance by the high aspect ratio particles. In summary, our data indicate that TiO(2) NP shape alters pulmonary responses, with severity of responses being ranked as NS < NB1 < NB2.

  11. Differential Mouse Pulmonary Dose and Time Course Responses to Titanium Dioxide Nanospheres and Nanobelts

    PubMed Central

    Porter, Dale W.

    2013-01-01

    Three anatase titanium dioxide (TiO2) nanoparticles (NPs) were prepared; nanospheres (NSs), short nanobelts (NB1), and long nanobelts (NB2). These NPs were used to investigate the effect of NP shape and length on lung toxicity. Mice were exposed (0–30 µg per mouse) by pharyngeal aspiration and pulmonary toxicity was assessed over a 112-day time course. Whole lung lavage data indicated that NB1- and NB2-exposed mice, but not NS-exposed mice, had significant dose- and time-dependent pulmonary inflammation and damage. Histopathological analyses at 112 days postexposure determined no interstitial fibrosis in any NS-exposed mice, an increased incidence in 30 µg NB1-exposed mice, and significant interstitial fibrosis in 30 µg NB2-exposed mice. At 112 days postexposure, lung burden of NS was decreased by 96.4% and NB2 by 80.5% from initial deposition levels. At 112 days postexposure, enhanced dark field microscopy determined that alveolar macro- phages were the dominant deposition site, but a fraction of NB1 and NB2 was observed in the alveolar interstitial spaces. For the 30 µg exposure groups at 112 days postexposure, confocal micro- scopy and immunofluorescent staining demonstrated that retained NB2 but not NS were present in the interstitium subjacent to the terminal bronchiole near the normal location of the smallest lymphatic capillaries in the lung. These lymphatic capillaries play a critical role in particle clearance, and the accumulation of NB2, but not NS, suggests possible impaired lymphatic clearance by the high aspect ratio particles. In summary, our data indicate that TiO2 NP shape alters pulmonary responses, with severity of responses being ranked as NS < NB1 < NB2. PMID:22956629

  12. 7 CFR 1206.21 - Suspend.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.21 Suspend. Suspend means...

  13. 7 CFR 1206.21 - Suspend.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.21 Suspend. Suspend means...

  14. 7 CFR 1206.21 - Suspend.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.21 Suspend. Suspend means...

  15. 7 CFR 1206.21 - Suspend.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.21 Suspend. Suspend means...

  16. 7 CFR 1206.21 - Suspend.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.21 Suspend. Suspend means...

  17. Fabrication of a self-sensing electroactive polymer bimorph actuator based on polyvinylidene fluoride and its electrostrictive terpolymer

    NASA Astrophysics Data System (ADS)

    Engel, Leeya; Van Volkinburg, Kyle R.; Ben-David, Moti; Washington, Gregory N.; Krylov, Slava; Shacham-Diamand, Yosi

    2016-04-01

    In this paper, we report on the fabrication of a self-sensing electroactive polymer cantilevered bimorph beam actuator and its frequency response. Tip deflections of the beam, induced by applying an AC signal across ferroelectric relaxor polyvinylidene fluoride-trifluoroethylene chlorotrifluoroethylene (P(VDF-TrFE-CTFE)), reached a magnitude of 350μm under a field of ~55MV/m and were recorded externally using a laser Doppler vibrometer (LDV). Deflections were determined simultaneously by applying a sensing model to the voltage measured across the bimorph's integrated layer of piezoelectric polymer polyvinylidene fluoride (PVDF). The sensing model treats the structure as a simple Euler- Bernoulli cantilevered beam with two distributed active elements represented through the use of generalized functions and offers a method through which real time tip deflection can be measured without the need for external visualization. When not being used as a sensing element, the PVDF layer can provide an additional means for actuation of the beam via the converse piezoelectric effect, resulting in bidirectional control of the beam's deflections. Integration of flexible sensing elements together with modeling of the electroactive polymer beam can benefit the developing field of polymer microactuators which have applications in soft robotics as "smart" prosthetics/implants, haptic displays, tools for less invasive surgery, and sensing.

  18. Vanadium nanobelts coated nickel foam 3D bifunctional electrode with excellent catalytic activity and stability for water electrolysis

    NASA Astrophysics Data System (ADS)

    Yu, Yu; Li, Pei; Wang, Xiaofang; Gao, Wenyu; Shen, Zongxu; Zhu, Yanan; Yang, Shuliang; Song, Weiguo; Ding, Kejian

    2016-05-01

    Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity.Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity. Electronic supplementary information (ESI) available: More SEM, TEM images, XRD patterns, LSV curves, XPS spectra. See DOI: 10.1039/c6nr02395a

  19. High-aspect-ratio HfC nanobelts accompanied by HfC nanowires: Synthesis, characterization and field emission properties

    NASA Astrophysics Data System (ADS)

    Tian, Song; Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang; Li, Hejun

    2017-04-01

    As a key refractory carbide, hafnium carbide (HfC) is commonly used as structural materials while the field emission (FE) application of HfC in the field of vacuum microelectronics is almost the only one for functional material purposes. Based on its outstanding physical and chemical characteristics, HfC is identified as a potential candidate with satisfactory mechanical properties and long-term and/or high-temperature FE stability for future applications in high-performance field emitters. However, the development of HfC in various FE applications is hindered because it is not facile to fabricate large-scale low-dimensional HfC field nanoemitters. Herein, High-aspect-ratio HfC nanobelts accompanied by HfC nanowires were synthesized on a large scale by a traditional and simple catalytic chemical vapor deposition (CVD) method. Classical vapor-liquid-solid (VLS) theory was employed to explain the growth of the HfC nanowires and nanobelts along axial direction. The thin HfO2 shell and thin C layer surrounding the nanostructures might give rise to the diameter fluctuation of HfC nanowires and the width increase of HfC nanobelts in lateral direction. Field emission results show that the high-aspect-ratio HfC nanobelts accompanied by the nanowires are promising field nanoemitters, which exhibit excellent field emission properties with a fairly low turn-on field of ∼1.5 V μm-1 and a low current fluctuation less than ∼10%. This suggests that HfC ceramics with high-aspect-ratio nanostructures are ideal cathode material for various field emission applications.

  20. Enhanced degradation of persistent pharmaceuticals found in wastewater treatment effluents using TiO2 nanobelt photocatalysts

    NASA Astrophysics Data System (ADS)

    Liang, Robert; Hu, Anming; Li, Wenjuan; Zhou, Y. Norman

    2013-10-01

    Pharmaceuticals in wastewater effluents are a current and emerging global problem and the development of cost-effective methods to facilitate their removal is needed to mitigate this issue. Advanced oxidation processes (AOPs), in particular UV/TiO2, have potential for wastewater treatment. In this study, TiO2 anatase phase nanobelts (30-100 nm in width and 10 μm in length) have been synthesized using a high temperature hydrothermal method as a means to photocatalyze the oxidation of pharmaceutical contaminants. We have investigated a model dye (malachite green), three pharmaceuticals and personal care products—naproxen, carbamazepine, and theophylline—that are difficult to oxidize without AOP processes. TiO2 nanobelts were exposed to 365 nm UV illumination and the measured photocatalytic degradation rates and adsorption parameters of pharmaceuticals were explored using kinetic models. Furthermore we have determined the degree of pharmaceutical degradation as a function of solution pH, illumination time, temperature, and concentration of contaminant. In addition, the roles of active oxygen species—hydroxyl radial (OH·), positive holes (h+), and hydrogen peroxide (H2O2)—involved were also investigated in the degradation process. These studies offer additional applications of hierarchical TiO2 nanobelt membranes, including those harnessing sunlight for water treatment.

  1. V2O5-C-SnO2 Hybrid Nanobelts as High Performance Anodes for Lithium-ion Batteries

    PubMed Central

    Zhang, Linfei; Yang, Mingyang; Zhang, Shengliang; Wu, Zefei; Amini, Abbas; Zhang, Yi; Wang, Dongyong; Bao, Shuhan; Lu, Zhouguang; Wang, Ning; Cheng, Chun

    2016-01-01

    The superior performance of metal oxide nanocomposites has introduced them as excellent candidates for emerging energy sources, and attracted significant attention in recent years. The drawback of these materials is their inherent structural pulverization which adversely impacts their performance and makes the rational design of stable nanocomposites a great challenge. In this work, functional V2O5-C-SnO2 hybrid nanobelts (VCSNs) with a stable structure are introduced where the ultradispersed SnO2 nanocrystals are tightly linked with glucose on the V2O5 surface. The nanostructured V2O5 acts as a supporting matrix as well as an active electrode component. Compared with existing carbon-V2O5 hybrid nanobelts, these hybrid nanobelts exhibit a much higher reversible capacity and architectural stability when used as anode materials for lithium-ion batteries. The superior cyclic performance of VCSNs can be attributed to the synergistic effects of SnO2 and V2O5. However, limited data are available for V2O5-based anodes in lithium-ion battery design. PMID:27677326

  2. Mechanism and optimization of pH sensing using SnO2 nanobelt field effect transistors.

    PubMed

    Cheng, Yi; Xiong, P; Yun, C Steven; Strouse, G F; Zheng, J P; Yang, R S; Wang, Z L

    2008-12-01

    We report a systematic investigation about the mechanism of pH sensing using SnO2 nanobelt field effect transistors (FETs). The FETs, based on single SnO2 nanobelts, are channel-limited and with proper contact passivation; the pH sensing was conducted with sodium phosphate solutions through integrated microfluidics. The responses of the FET channel conductance to pH were measured at different gate voltages: a linear pH dependence was observed in the linear transport "on" state, while an exponential dependence was observed in the subthreshold regime. Measurements at the same pH but different ion concentrations demonstrated that the FET's pH sensitivity decreases logarithmically with the ion concentration. The effect of APTES-functionalization was evaluated by comparing the pH responses of the same device with and without the surface modification. The APTES functionalization results in a slight enhancement of the pH sensitivity and a large suppression of the noise level, leading to marked improvement in the signal-to-noise ratio. The results indicate that the pH sensing is based on a screened field-effect response of the FETs to the surface protonation/deprotonation on the nanobelt. This study provides several useful guidelines for optimizing the sensor performance for chemical and biomolecular detection.

  3. Functionalized SnO₂ nanobelt field-effect transistor sensors for label-free detection of cardiac troponin.

    PubMed

    Cheng, Yi; Chen, Kan-Sheng; Meyer, Nancy L; Yuan, Jing; Hirst, Linda S; Chase, P Bryant; Xiong, Peng

    2011-07-15

    Real-time label-free electrical detection of proteins, including cardiac troponin (cTn), is demonstrated using functionalized SnO₂ nanobelt field-effect transistors (FETs) with integrated microfluidics. Selective biomolecular functionalization of the active SnO₂ nanobelt channel and effective passivation of the substrate surface were realized and verified through fluorescence microscopy. The validation/verification of the sensing scheme was initially demonstrated via detection of biotin-streptavidin binding: devices with single biotinylated SnO₂ nanobelts showed pronounced conductance changes in response to streptavidin binding. Importantly, the pH-dependence of the conductance changes was fully consistent with the charged states of streptavidin at different pH. Moreover, the specificity of the sensors' electrical responses was confirmed by co-labeling with quantum dots. Finally, the sensing platform was successfully applied for detection of the cardiac troponin I (cTnI) subunit within cTn, a clinically important protein marker for myocardial infarction.

  4. V2O5-C-SnO2 Hybrid Nanobelts as High Performance Anodes for Lithium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Linfei; Yang, Mingyang; Zhang, Shengliang; Wu, Zefei; Amini, Abbas; Zhang, Yi; Wang, Dongyong; Bao, Shuhan; Lu, Zhouguang; Wang, Ning; Cheng, Chun

    2016-09-01

    The superior performance of metal oxide nanocomposites has introduced them as excellent candidates for emerging energy sources, and attracted significant attention in recent years. The drawback of these materials is their inherent structural pulverization which adversely impacts their performance and makes the rational design of stable nanocomposites a great challenge. In this work, functional V2O5-C-SnO2 hybrid nanobelts (VCSNs) with a stable structure are introduced where the ultradispersed SnO2 nanocrystals are tightly linked with glucose on the V2O5 surface. The nanostructured V2O5 acts as a supporting matrix as well as an active electrode component. Compared with existing carbon-V2O5 hybrid nanobelts, these hybrid nanobelts exhibit a much higher reversible capacity and architectural stability when used as anode materials for lithium-ion batteries. The superior cyclic performance of VCSNs can be attributed to the synergistic effects of SnO2 and V2O5. However, limited data are available for V2O5-based anodes in lithium-ion battery design.

  5. A Single Eu-Doped In2O3 Nanobelt Device for Selective H2S Detection

    PubMed Central

    Chen, Weiwu; Liu, Yingkai; Qin, Zhaojun; Wu, Yuemei; Li, Shuanghui; Ai, Peng

    2015-01-01

    Eu-doped In2O3 nanobelts (Eu-In2O3 NBs) and pure In2O3 nanobelts (In2O3 NBs) are synthesized by the carbon thermal reduction method. Single nanobelt sensors are fabricated via an ion beam deposition system with a mesh-grid mask. The gas-sensing response properties of the Eu-In2O3 NB device and its undoped counterpart are investigated with several kinds of gases (including H2S, CO, NO2, HCHO, and C2H5OH) at different concentrations and different temperatures. It is found that the response of the Eu-In2O3 NB device to 100 ppm of H2S is the best among these gases and the sensitivity reaches 5.74, which is five times that of pure In2O3 NB at 260 °C. We also found that the former has an excellent sensitive response and great selectivity to H2S compared to the latter. Besides, there is a linear relationship between the response and H2S concentration when its concentration changes from 5 to 100 ppm and from 100 to 1000 ppm. The response/recovery time is quite short and remains stable with an increase of H2S concentration. These results mean that the doping of Eu can improve the gas-sensing performance of In2O3 NB effectually. PMID:26633404

  6. Substrate-free fabrication of self-supported V2O5 nanobelt arrays by a low-temperature solvothermal method with high electrochemical performance.

    PubMed

    Xu, Haitao; Zhang, Huijuan; Liu, Li; Fang, Ling; Wang, Yu

    2016-08-05

    In the designed synthesis, self-supported NH4V3O8 nanobelt arrays were prepared via a low-temperature solvothermal method. Then the NH4V3O8 nanobelt arrays were calcined in air atmosphere. Finally, a self-supported pattern of oriented V2O5 nanobelts was obtained for the first time. Further characterization methods certified that the growth direction of NH4V3O8 nanobelts was perpendicular to the orientation plane of self-formed NH4V3O8 sheet-like substrates. As a result, the nanobelts should stretch easily on the sheet-like substrate in an oriented manner. We prove that the solvent of ethanol plays a key role in the reaction and crystal growth process. It balances the two competing oxolation and olation reactions. Furthermore, the unique pattern served as high performance a lithium-ion battery and supercapacitor. Overall, the excellent electrochemical performances, for example, outstanding rate stability, remarkable cycling capacitance and ultrahigh capacity verify that the self-supported alignments have great potential applications in lithium-ion batteries and supercapacitors.

  7. Substrate-free fabrication of self-supported V2O5 nanobelt arrays by a low-temperature solvothermal method with high electrochemical performance

    NASA Astrophysics Data System (ADS)

    Xu, Haitao; Zhang, Huijuan; Liu, Li; Fang, Ling; Wang, Yu

    2016-08-01

    In the designed synthesis, self-supported NH4V3O8 nanobelt arrays were prepared via a low-temperature solvothermal method. Then the NH4V3O8 nanobelt arrays were calcined in air atmosphere. Finally, a self-supported pattern of oriented V2O5 nanobelts was obtained for the first time. Further characterization methods certified that the growth direction of NH4V3O8 nanobelts was perpendicular to the orientation plane of self-formed NH4V3O8 sheet-like substrates. As a result, the nanobelts should stretch easily on the sheet-like substrate in an oriented manner. We prove that the solvent of ethanol plays a key role in the reaction and crystal growth process. It balances the two competing oxolation and olation reactions. Furthermore, the unique pattern served as high performance a lithium-ion battery and supercapacitor. Overall, the excellent electrochemical performances, for example, outstanding rate stability, remarkable cycling capacitance and ultrahigh capacity verify that the self-supported alignments have great potential applications in lithium-ion batteries and supercapacitors.

  8. Carbon-coated Magnéli-phase TinO2n-1 nanobelts as anodes for Li-ion batteries and hybrid electrochemical cells

    NASA Astrophysics Data System (ADS)

    Han, Wei-Qiang; Wang, Xiao-Liang

    2010-12-01

    We describe a method for preparing carbon-coated Ti9O17 nanowires using H2Ti3O7 nanobelts as precursors to react with ethane and hydrogen at high-temperature. The carbon-coating layers play a key role in restraining the sintering growth of the core during the phase transformation from H2Ti3O7 to Magnéli-phase TinO2n-1, and in retaining the morphology of nanobelts. We demonstrated that the initial reversible capacity of these Ti9O17 nanobelts attained 182 mA h g-1, a value even higher than the theoretical value of a-TiO2 (167 mA h g-1). Cyclic-voltammetry measurement supports the pseudocapacitive lithium-storage behavior of these Magnéli-phase Ti9O17 nanobelts. Furthermore, the nanobelts exhibit high power density along with excellent cycling stability in their application as hybrid electrochemical cells.

  9. Yellow-light generation and engineering in zinc-doped cadmium sulfide nanobelts with low-threshold two-photon excitation.

    PubMed

    Wang, Xiaoxu; Li, Jing; Li, Qisong; Chen, Bingkun; Song, Guangli; Zhang, Wensheng; Shi, Lijie; Zou, Bingsuo; Liu, Ruibin

    2014-08-15

    Through a simple doping route with zinc ion as a dopant in cadmium sulfide nanobelts, a bright yellow-colored light was obtained. The detailed chromaticity and brightness of the light can be engineered by the dopant concentration and the pumping power, which are used to control the dominant wavelength to any fine yellow color, and even cover the sodium-yellow-line of 589 nm. The nanobelts were synthesized through a chemical vapor deposition method. The peak shift of the XRD result proves that the zinc ions as a dopant exist in the nanobelts rather than in the ZnCdS alloy formation. Time-resolved photoluminescence of the nanobelt reveals the existence of the defect-related state, which induces a red band to further mix with green band-edge emission to form the yellow light. Moreover, low-threshold two-photon excitation was observed in the proper Zn-doped cadmium sulfide nanobelts. The dopant and pumping power-tuned generation and engineering of the yellow light makes it possible to use this kind of material as yellow light-emitting source.

  10. Wettability of partially suspended graphene

    PubMed Central

    Ondarçuhu, Thierry; Thomas, Vincent; Nuñez, Marc; Dujardin, Erik; Rahman, Atikur; Black, Charles T.; Checco, Antonio

    2016-01-01

    The dependence of the wettability of graphene on the nature of the underlying substrate remains only partially understood. Here, we systematically investigate the role of liquid-substrate interactions on the wettability of graphene by varying the area fraction of suspended graphene from 0 to 95% by means of nanotextured substrates. We find that completely suspended graphene exhibits the highest water contact angle (85° ± 5°) compared to partially suspended or supported graphene, regardless of the hydrophobicity (hydrophilicity) of the substrate. Further, 80% of the long-range water-substrate interactions are screened by the graphene monolayer, the wettability of which is primarily determined by short-range graphene-liquid interactions. By its well-defined chemical and geometrical properties, supported graphene therefore provides a model system to elucidate the relative contribution of short and long range interactions to the macroscopic contact angle. PMID:27072195

  11. Wettability of partially suspended graphene

    DOE PAGES

    Ondarçuhu, Thierry; Thomas, Vincent; Nuñez, Marc; ...

    2016-04-13

    Dependence on the wettability of graphene on the nature of the underlying substrate remains only partially understood. We systematically investigate the role of liquid-substrate interactions on the wettability of graphene by varying the area fraction of suspended graphene from 0 to 95% by means of nanotextured substrates. We find that completely suspended graphene exhibits the highest water contact angle (85° ± 5°) compared to partially suspended or supported graphene, regardless of the hydrophobicity (hydrophilicity) of the substrate. Moreover, 80% of the long-range water-substrate interactions are screened by the graphene monolayer, the wettability of which is primarily determined by short-range graphene-liquidmore » interactions. By its well-defined chemical and geometrical properties, supported graphene therefore provides a model system to elucidate the relative contribution of short and long range interactions to the macroscopic contact angle.« less

  12. Wettability of partially suspended graphene

    SciTech Connect

    Ondarçuhu, Thierry; Thomas, Vincent; Nuñez, Marc; Dujardin, Erik; Rahman, Atikur; Black, Charles T.; Checco, Antonio

    2016-04-13

    Dependence on the wettability of graphene on the nature of the underlying substrate remains only partially understood. We systematically investigate the role of liquid-substrate interactions on the wettability of graphene by varying the area fraction of suspended graphene from 0 to 95% by means of nanotextured substrates. We find that completely suspended graphene exhibits the highest water contact angle (85° ± 5°) compared to partially suspended or supported graphene, regardless of the hydrophobicity (hydrophilicity) of the substrate. Moreover, 80% of the long-range water-substrate interactions are screened by the graphene monolayer, the wettability of which is primarily determined by short-range graphene-liquid interactions. By its well-defined chemical and geometrical properties, supported graphene therefore provides a model system to elucidate the relative contribution of short and long range interactions to the macroscopic contact angle.

  13. Growth of Fe2O3/SnO2 nanobelt arrays on iron foil for efficient photocatalytic degradation of methylene blue

    NASA Astrophysics Data System (ADS)

    Lei, Rui; Ni, Hongwei; Chen, Rongsheng; Zhang, Bowei; Zhan, Weiting; Li, Yang

    2017-04-01

    Tin(IV) oxide has been intensively employed in optoelectronic devices due to its excellent electrical and optical properties. But the high recombination rates of the photogenerated electron-hole pairs of SnO2 nanomaterials often results in low photocatalytic efficiency. Herein, we proposed a facile route to prepare a novel Fe2O3/SnO2 heterojunction structure. The nanobelt arrays grown on iron foil naturally form a Schottky-type contact and provide a direct pathway for the photogenerated excitons. Hence, the Fe2O3/SnO2 nanobelt arrays exhibit much improved photocatalytic performance with the degradation rate constant on the Fe2O3/SnO2 film of approximately 12 times to that of α-Fe2O3 nanobelt arrays.

  14. Suspended animation for delayed resuscitation.

    PubMed

    Bellamy, R; Safar, P; Tisherman, S A; Basford, R; Bruttig, S P; Capone, A; Dubick, M A; Ernster, L; Hattler, B G; Hochachka, P; Klain, M; Kochanek, P M; Kofke, W A; Lancaster, J R; McGowan, F X; Oeltgen, P R; Severinghaus, J W; Taylor, M J; Zar, H

    1996-02-01

    Suspended animation is defined as the therapeutic induction of a state of tolerance to temporary complete systemic ischemia, i.w., protection-preservation of the whole organism during prolonged circulatory arrest ( > or = 1 hr), followed by resuscitation to survival without brain damage. The objectives of suspended animation include: a) helping to save victims of temporarily uncontrollable (internal) traumatic (e.g., combat casualties) or nontraumatic (e.g., ruptured aortic aneurysm) exsanguination, without severe brain trauma, by enabling evacuation and resuscitative surgery during circulatory arrest, followed by delayed resuscitation; b) helping to save some nontraumatic cases of sudden death, seemingly unresuscitable before definite repair; and c) enabling selected (elective) surgical procedures to be performed which are only feasible during a state of no blood flow. In the discussion session, investigators with suspended animation-relevant research interests brainstorm on present knowledge, future research potentials, and the advisability of a major research effort concerning this subject. The following topics are addressed: the epidemiologic facts of sudden death in combat casualties, which require a totally new resuscitative approach; the limits and potentials of reanimation research; complete reversibility of circulatory arrest of 1 hr in dogs under profound hypothermia ( < 10 degrees C), induced and reversed by portable cardiopulmonary bypass; the need for a still elusive pharmacologic or chemical induction of suspended animation in the field; asanguinous profound hypothermic low-flow with cardiopulmonary bypass; electric anesthesia; opiate therapy; lessons learned by hypoxia tolerant vertebrate animals, hibernators, and freeze-tolerant animals (cryobiology); myocardial preservation during open-heart surgery; organ preservation for transplantation; and reperfusion-reoxygenation injury in vital organs, including the roles of nitric oxide and free radicals

  15. Magnetically suspended reaction wheel assembly

    NASA Technical Reports Server (NTRS)

    Stocking, G.

    1984-01-01

    The magnetically suspended reaction wheel assembly (MSRWA) is the product of a development effort funded by the Air Force Materials Laboratory (AFML) at Wright Patterson AFB. The specific objective of the project was to establish the manufacturing processes for samarium cobalt magnets and demonstrate their use in a space application. The development was successful on both counts. The application portion of the program, which involves the magnetically suspended reaction wheel assembly, is emphasized. The requirements for the reaction wheel were based on the bias wheel requirements of the DSP satellite. The tasks included the design, fabrication, and test of the unit to the DSP program qualification requirements.

  16. A Finite Element Model Of Self-Resonating Bimorph Microcantilever For Fast Temperature Cycling In A Pyroelectric Energy Harvester

    SciTech Connect

    Mostafa, Salwa; Lavrik, Nickolay V; Bannuru, Thirumalesh; Rajic, Slobodan; Islam, Syed K; Datskos, Panos G; Hunter, Scott Robert

    2011-01-01

    A self resonating bimorph cantilever structure for fast temperature cycling in a pyroelectric energy harvester has been modeled using a finite element method. The effect of constituting material properties and system parameters on the frequency and magnitude of temperature cycling and the efficiency of energy recycling using the proposed structure has been investigated. Results show that thermal contact conductance and heat source temperature play a key role in dominating the cycling frequency and efficiency of energy recycling. An optimal solution for the most efficient energy scavenging process has been sought by studying the performance trend with different variable parameters such as thermal contact conductance, heat source temperature, device aspect ratio and constituent materials of varying thermal conductivity and expansion coefficients.

  17. Creating flat-top X-ray beams by applying surface profiles of alternating curvature to deformable piezo bimorph mirrors

    PubMed Central

    Sutter, John P.; Alcock, Simon G.; Kashyap, Yogesh; Nistea, Ioana; Wang, Hongchang; Sawhney, Kawal

    2016-01-01

    Beam shaping is becoming increasingly important for synchrotron X-ray applications. Although routine for visible light lasers, this is challenging for X-rays due to the limited source coherence and extreme optical tolerances required for the shaping mirrors. In deliberate defocusing, even surface errors <5 nm r.m.s. introduce damagingly large striations into the reflected beam. To counteract such problems, surface modifications with alternating concave and convex curvature on equal segments were polished onto the surface of non-active mirrors of fixed curvature. Such optics are useful for providing a fixed size of X-ray beam, but do not provide the adaptability required by many experiments. In contrast, deformable piezo bimorph mirrors permit a continuous range of X-ray beam sizes and shapes. A new theory is developed for applying non-periodic modifications of alternating curvature to optical surfaces. The position and length of the segments may be freely chosen. For the first time, surface modifications of alternating curvature are applied to bimorph mirrors to generate non-Gaussian X-ray beam profiles of specified width. The new theory’s freedom is exploited to choose the segments to match the polishing errors of medium wavelength (>10 mm) and the piezos’ influence on the mirror’s figure. Five- and seven-segment modifications of alternating curvature are calculated and verified by visible light and X-ray metrology. The latter yields beam profiles with less striation than those made by defocusing. Remaining beam striations are explained by applying geometrical optics to the deviations from the ideal surface modifications of alternating curvature. PMID:27787239

  18. Creating flat-top X-ray beams by applying surface profiles of alternating curvature to deformable piezo bimorph mirrors.

    PubMed

    Sutter, John P; Alcock, Simon G; Kashyap, Yogesh; Nistea, Ioana; Wang, Hongchang; Sawhney, Kawal

    2016-11-01

    Beam shaping is becoming increasingly important for synchrotron X-ray applications. Although routine for visible light lasers, this is challenging for X-rays due to the limited source coherence and extreme optical tolerances required for the shaping mirrors. In deliberate defocusing, even surface errors <5 nm r.m.s. introduce damagingly large striations into the reflected beam. To counteract such problems, surface modifications with alternating concave and convex curvature on equal segments were polished onto the surface of non-active mirrors of fixed curvature. Such optics are useful for providing a fixed size of X-ray beam, but do not provide the adaptability required by many experiments. In contrast, deformable piezo bimorph mirrors permit a continuous range of X-ray beam sizes and shapes. A new theory is developed for applying non-periodic modifications of alternating curvature to optical surfaces. The position and length of the segments may be freely chosen. For the first time, surface modifications of alternating curvature are applied to bimorph mirrors to generate non-Gaussian X-ray beam profiles of specified width. The new theory's freedom is exploited to choose the segments to match the polishing errors of medium wavelength (>10 mm) and the piezos' influence on the mirror's figure. Five- and seven-segment modifications of alternating curvature are calculated and verified by visible light and X-ray metrology. The latter yields beam profiles with less striation than those made by defocusing. Remaining beam striations are explained by applying geometrical optics to the deviations from the ideal surface modifications of alternating curvature.

  19. Fabrication and performance evaluation of a metal-based bimorph piezoelectric MEMS generator for vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Kuo, Chun-Liang; Lin, Shun-Chiu; Wu, Wen-Jong

    2016-10-01

    This paper presents the development of a bimorph microelectromechanical system (MEMS) generator for vibration energy harvesting. The bimorph generator is in cantilever beam structure formed by laminating two lead zirconate titanate thick-film layers on both sides of a stainless steel substrate. Aiming to scavenge vibration energy efficiently from the environment and transform into useful electrical energy, the two piezoelectric layers on the device can be poled for serial and parallel connections to enhance the output voltage or output current respectively. In addition, a tungsten proof mass is bonded at the tip of the device to adjust the resonance frequency. The experimental result shows superior performance the generator. At the 0.5 g base excitation acceleration level, the devices pooled for serial connection and the device poled for parallel connection possess an open-circuit output voltage of 11.6 VP-P and 20.1 VP-P, respectively. The device poled for parallel connection reaches a maximum power output of 423 μW and an output voltage of 15.2 VP-P at an excitation frequency of 143.4 Hz and an externally applied based excitation acceleration of 1.5 g, whereas the device poled serial connection achieves a maximum power output of 413 μW and an output voltage of 33.0 VP-P at an excitation frequency of 140.8 Hz and an externally applied base excitation acceleration of 1.5 g. To demonstrate the feasibility of the MEMS generator for real applications, we finished the demonstration of a self-powered Bluetooth low energy wireless temperature sensor sending readings to a smartphone with only the power from the MEMS generator harvesting from vibration.

  20. Optimizing the electrode size of circular bimorph plates with different boundary conditions for maximum deflection of piezoelectric micromachined ultrasonic transducers.

    PubMed

    Sammoura, Firas; Smyth, Katherine; Kim, Sang-Gook

    2013-02-01

    The effect of plate electrode area on the deflection of a symmetric circular bimorph piezoelectric micromachined ultrasonic transducer (pMUT) with clamped and simply supported boundary conditions was studied for the first time. Distinct plate displacement shape functions were defined for the regions underneath and outside the active electrodes. The plate shape functions were solved analytically using classic plate theory in conjunction with the external boundary conditions and the internal ones between the two regions in order to calculate the exact plate displacement under both external voltage stimulus and acoustic pressure. The model was used to study the effect of the electrode area on the overall plate deflection per unit input voltage such that the electromechanical coupling is optimized. While the center plate deflection increased monotonically with the electrode area for a simply supported plate, it followed a parabolic shape for a clamped one with a maximum deflection when the electrode radius covered 60% of the total plate radius. The simply supported plate exhibited four times the plate deflection capability of its clamped counterpart, when both are operating at their optimal electrode size. Both an experimental clamped bimorph aluminum nitride (AlN) pMUT, recently reported in the literature, and Finite Element Modeling (FEM) were used to verify the developed model. The theoretical model predicted a static displacement per unit voltage of 10.9nm/V and a resonant frequency of 196.5kHz, which were in excellent agreement with the FEM results of 10.32nm/V and 198.5kHz, respectively. The modeling data matched well with the experimental measurements and the error ranged from 2.7-22% due to process variations across the wafer. As such, the developed model can be used to design more sensitive pMUTs or extract the flexural piezoelectric coefficient using piezoelectrically actuated circular plates.

  1. Toward clean suspended CVD graphene

    SciTech Connect

    Yulaev, Alexander; Cheng, Guangjun; Hight Walker, Angela R.; Vlassiouk, Ivan V.; Myers, Alline; Leite, Marina S.; Kolmakov, Andrei

    2016-08-26

    The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the target of interest. Here, we use thermally evaporated anthracene films as the sacrificial layer for graphene transfer onto an arbitrary substrate. We show that clean suspended graphene can be achieved via desorbing the anthracene layer at temperatures in the 100 °C to 150 °C range, followed by two sequential annealing steps for the final cleaning, using a Pt catalyst and activated carbon. The cleanliness of the suspended graphene membranes was analyzed employing the high surface sensitivity of low energy scanning electron microscopy and X-ray photoelectron spectroscopy. A quantitative comparison with two other commonly used transfer methods revealed the superiority of the anthracene approach to obtain a larger area of clean, suspended CVD graphene. Lastly, our graphene transfer method based on anthracene paves the way for integrating cleaner graphene in various types of complex devices, including the ones that are heat and humidity sensitive.

  2. Toward Clean Suspended CVD Graphene.

    PubMed

    Yulaev, Alexander; Cheng, Guangjun; Walker, Angela R Hight; Vlassiouk, Ivan V; Myers, Alline; Leite, Marina S; Kolmakov, Andrei

    2016-01-01

    The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the target of interest. Here, we use thermally evaporated anthracene films as the sacrificial layer for graphene transfer onto an arbitrary substrate. We show that clean suspended graphene can be achieved via desorbing the anthracene layer at temperatures in the 100 °C to 150 °C range, followed by two sequential annealing steps for the final cleaning, using Pt catalyst and activated carbon. The cleanliness of the suspended graphene membranes was analyzed employing the high surface sensitivity of low energy scanning electron microscopy and x-ray photoelectron spectroscopy. A quantitative comparison with two other commonly used transfer methods revealed the superiority of the anthracene approach to obtain larger area of clean, suspended CVD graphene. Our graphene transfer method based on anthracene paves the way for integrating cleaner graphene in various types of complex devices, including the ones that are heat and humidity sensitive.

  3. Modulation of electronic properties of tin oxide nanobelts via thermal control of surface oxygen defects.

    PubMed

    Keiper, Timothy D; Barreda, Jorge L; Zheng, Jim P; Xiong, Peng

    2017-02-03

    Nanomaterials made from binary metal oxides are of increasing interest because of their versatility in applications from flexible electronics to portable chemical and biological sensors. Controlling the electrical properties of these materials is the first step in device implementation. Tin dioxide (SnO2) nanobelts (NB) synthesized by the vapor-liquid-solid mechanism have shown much promise in this regard. We explore the modification of devices prepared with single crystalline NBs by thermal annealing in vacuum and oxygen, resulting in a viable field-effect transistor (FET) for numerous applications at ambient temperature. An oxygen annealing step initially increases the device conductance by up to a factor of 10(5), likely through the modification of the surface defects of the NB, leading to Schottky barrier limited devices. A multi-step annealing procedure leads to further increase of the conductance by approximately 350% and optimization of the electronic properties. The effects of each step is investigated systematically on a single NB. The optimization of the electrical properties of the NBs makes possible the consistent production of channel-limited FETs and control of the device performance. Understanding these improvements on the electrical properties over the as-grown materials provides a pathway to enhance and tailor the functionalities of tin oxide nanostructures for a wide variety of optical, electronic, optoelectronic, and sensing applications that operate at room temperature.

  4. Modulation of electronic properties of tin oxide nanobelts via thermal control of surface oxygen defects

    NASA Astrophysics Data System (ADS)

    Keiper, Timothy D.; Barreda, Jorge L.; Zheng, Jim P.; Xiong, Peng

    2017-02-01

    Nanomaterials made from binary metal oxides are of increasing interest because of their versatility in applications from flexible electronics to portable chemical and biological sensors. Controlling the electrical properties of these materials is the first step in device implementation. Tin dioxide (SnO2) nanobelts (NB) synthesized by the vapor-liquid-solid mechanism have shown much promise in this regard. We explore the modification of devices prepared with single crystalline NBs by thermal annealing in vacuum and oxygen, resulting in a viable field-effect transistor (FET) for numerous applications at ambient temperature. An oxygen annealing step initially increases the device conductance by up to a factor of 105, likely through the modification of the surface defects of the NB, leading to Schottky barrier limited devices. A multi-step annealing procedure leads to further increase of the conductance by approximately 350% and optimization of the electronic properties. The effects of each step is investigated systematically on a single NB. The optimization of the electrical properties of the NBs makes possible the consistent production of channel-limited FETs and control of the device performance. Understanding these improvements on the electrical properties over the as-grown materials provides a pathway to enhance and tailor the functionalities of tin oxide nanostructures for a wide variety of optical, electronic, optoelectronic, and sensing applications that operate at room temperature.

  5. Controllable synthesis and electrochemical hydrogen storage properties of Sb2Se3 ultralong nanobelts with urchin-like structures

    NASA Astrophysics Data System (ADS)

    Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

    2011-09-01

    The controlled synthesis of one-dimensional and three-dimensional Sb2Se3 nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb2Se3 with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb2Se3 nanostructures. The Sb2Se3 ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g-1) and better cycle stability at room temperature.The controlled synthesis of one-dimensional and three-dimensional Sb2Se3 nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb2Se3 with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The

  6. Characterization of Sputtered Nickel-Titanium (NiTi) Stress and Thermally Actuated Cantilever Bimorphs Based on NiTi Shape Memory Alloy (SMA)

    DTIC Science & Technology

    2015-11-01

    Actuated Cantilever Bimorphs Based on NiTi Shape Memory Alloy (SMA) by Merric D Srour, Cory R Knick, and Christopher J Morris Sensors and...applications7 so a natural focus was to achieve large recovery stresses in films as thin as possible. By varying the sputtering parameters of NiTi...alloys. Sensors and Actuators A. 2002;99:55–58. 2. Ohta A, Bhansali S, Kishimoto I, Umeda A. Novel fabrication techique of TiNi shape memory alloy

  7. Suspended Solids Profiler Shop Test Report

    SciTech Connect

    STAEHR, T.W.

    2000-01-19

    The Suspended Solids Profiler (SSP) Instrument is planned to be installed in the AZ-101 tank to measure suspended solids concentrations during mixer pump testing. The SSP sensor uses a reflectance measurement principle to determine the suspended solids concentrations. The purpose of this test is to provide a documented means of verifying that the functional components of the SSP operate properly.

  8. 21 CFR 1404.1010 - Suspending official.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Suspending official. 1404.1010 Section 1404.1010 Food and Drugs OFFICE OF NATIONAL DRUG CONTROL POLICY GOVERNMENTWIDE DEBARMENT AND SUSPENSION (NONPROCUREMENT) Definitions § 1404.1010 Suspending official. (a) Suspending official means an agency official...

  9. 30 CFR 57.16009 - Suspended loads.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Suspended loads. 57.16009 Section 57.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 57.16009 Suspended loads. Persons shall stay clear of suspended loads....

  10. 30 CFR 56.16009 - Suspended loads.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Suspended loads. 56.16009 Section 56.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 56.16009 Suspended loads. Persons shall stay clear of suspended loads....

  11. 30 CFR 57.16009 - Suspended loads.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Suspended loads. 57.16009 Section 57.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 57.16009 Suspended loads. Persons shall stay clear of suspended loads....

  12. 30 CFR 57.16009 - Suspended loads.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Suspended loads. 57.16009 Section 57.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 57.16009 Suspended loads. Persons shall stay clear of suspended loads....

  13. 30 CFR 56.16009 - Suspended loads.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Suspended loads. 56.16009 Section 56.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 56.16009 Suspended loads. Persons shall stay clear of suspended loads....

  14. 30 CFR 56.16009 - Suspended loads.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Suspended loads. 56.16009 Section 56.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 56.16009 Suspended loads. Persons shall stay clear of suspended loads....

  15. 30 CFR 56.16009 - Suspended loads.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Suspended loads. 56.16009 Section 56.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 56.16009 Suspended loads. Persons shall stay clear of suspended loads....

  16. 30 CFR 57.16009 - Suspended loads.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Suspended loads. 57.16009 Section 57.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 57.16009 Suspended loads. Persons shall stay clear of suspended loads....

  17. 30 CFR 57.16009 - Suspended loads.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Suspended loads. 57.16009 Section 57.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 57.16009 Suspended loads. Persons shall stay clear of suspended loads....

  18. 30 CFR 56.16009 - Suspended loads.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Suspended loads. 56.16009 Section 56.16009 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Handling § 56.16009 Suspended loads. Persons shall stay clear of suspended loads....

  19. Toward clean suspended CVD graphene

    DOE PAGES

    Yulaev, Alexander; Cheng, Guangjun; Hight Walker, Angela R.; ...

    2016-08-26

    The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the target of interest. Here, we use thermally evaporated anthracene films as the sacrificial layer for graphene transfer onto an arbitrary substrate. We show that clean suspended graphene can be achieved via desorbing the anthracene layer at temperatures in the 100 °C to 150 °C range, followed by two sequential annealing steps for the final cleaning, using a Pt catalyst and activated carbon. The cleanliness of the suspendedmore » graphene membranes was analyzed employing the high surface sensitivity of low energy scanning electron microscopy and X-ray photoelectron spectroscopy. A quantitative comparison with two other commonly used transfer methods revealed the superiority of the anthracene approach to obtain a larger area of clean, suspended CVD graphene. Lastly, our graphene transfer method based on anthracene paves the way for integrating cleaner graphene in various types of complex devices, including the ones that are heat and humidity sensitive.« less

  20. Highly porous NiCo2O4 Nanoflakes and nanobelts as anode materials for lithium-ion batteries with excellent rate capability.

    PubMed

    Mondal, Anjon Kumar; Su, Dawei; Chen, Shuangqiang; Xie, Xiuqiang; Wang, Guoxiu

    2014-09-10

    Highly porous NiCo2O4 nanoflakes and nanobelts were synthesized by using a hydrothermal technique, followed by calcination of the NiCo2O4 precursors. The as-synthesized materials were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Brunauer-Emmett-Teller methods. The NiCo2O4 nanoflakes and nanobelts were applied as anode materials for lithium-ion batteries. Owing to the unique porous structural features, the NiCo2O4 nanoflakes and nanobelts exhibited high specific capacities of 1033 and 1056 mA h g(-1), respectively, and good cycling stability and rate capability. These exceptional electrochemical performances could be ascribed to the remarkable structural feature with a high surface area and void spaces within the surface of nanoflakes and nanobelts, which provide large contact areas between electrolyte and active materials for electrolyte diffusion and cushion the volume variation during the lithium-ion insertion/extraction process.

  1. Exfoliated β-Ga2O3 nano-belt field-effect transistors for air-stable high power and high temperature electronics.

    PubMed

    Kim, Janghyuk; Oh, Sooyeoun; Mastro, Michael A; Kim, Jihyun

    2016-06-21

    This study demonstrated the exfoliation of a two-dimensional (2D) β-Ga2O3 nano-belt and subsequent processing into a thin film transistor structure. This mechanical exfoliation and transfer method produces β-Ga2O3 nano-belts with a pristine surface as well as a continuous defect-free interface with the SiO2/Si substrate. This β-Ga2O3 nano-belt based transistor displayed an on/off ratio that increased from approximately 10(4) to 10(7) over the operating temperature range of 20 °C to 250 °C. No electrical breakdown was observed in our measurements up to VDS = +40 V and VGS = -60 V between 25 °C and 250 °C. Additionally, the electrical characteristics were not degraded after a month-long storage in ambient air. The demonstration of high-temperature/high-voltage operation of quasi-2D β-Ga2O3 nano-belts contrasts with traditional 2D materials such as transition metal dichalcogenides that intrinsically have limited temperature and power operational envelopes owing to their narrow bandgap. This work motivates the application of 2D β-Ga2O3 to high power nano-electronic devices for harsh environments such as high temperature chemical sensors and photodetectors as well as the miniaturization of power circuits and cooling systems in nano-electronics.

  2. High detectivity solar-blind high-temperature deep-ultraviolet photodetector based on multi-layered (l00) facet-oriented β-Ga₂O₃ nanobelts.

    PubMed

    Zou, Rujia; Zhang, Zhenyu; Liu, Qian; Hu, Junqing; Sang, Liwen; Liao, Meiyong; Zhang, Wenjun

    2014-05-14

    Fabrication of a high-temperature deep-ultraviolet photodetector working in the solar-blind spectrum range (190-280 nm) is a challenge due to the degradation in the dark current and photoresponse properties. Herein, β-Ga2O3 multi-layered nanobelts with (l00) facet-oriented were synthesized, and were demonstrated for the first time to possess excellent mechanical, electrical properties and stability at a high temperature inside a TEM studies. As-fabricated DUV solar-blind photodetectors using (l00) facet-oriented β-Ga2O3 multi-layered nanobelts demonstrated enhanced photodetective performances, that is, high sensitivity, high signal-to-noise ratio, high spectral selectivity, high speed, and high stability, importantly, at a temperature as high as 433 K, which are comparable to other reported semiconducting nanomaterial photodetectors. In particular, the characteristics of the photoresponsivity of the β-Ga2O3 nanobelt devices include a high photoexcited current (>21 nA), an ultralow dark current (below the detection limit of 10(-14) A), a fast time response (<0.3 s), a high R(λ) (≈851 A/W), and a high EQE (~4.2 × 10(3)). The present fabricated facet-oriented β-Ga2O3 multi-layered nanobelt based devices will find practical applications in photodetectors or optical switches for high-temperature environment.

  3. Self-assembly of palladium nanoparticles: Synthesis of nanobelts, nanoplates and nanotrees using vitamin B1 and their application in carbon-carbon coupling reactions

    EPA Science Inventory

    An environmentally friendly one-step method to synthesize palladium (Pd) nanobelts, nanoplates and nanotrees using vitamin B1 without using any special capping agents at room temperature is described. This greener method, which uses water as benign solvent and vitamin B1 as a red...

  4. Synthesis, characterization, and variable range hopping transport of pyrite (FeS₂) nanorods, nanobelts, and nanoplates.

    PubMed

    Cabán-Acevedo, Miguel; Liang, Dong; Chew, Kit S; Degrave, John P; Kaiser, Nicholas S; Jin, Song

    2013-02-26

    We report the growth, structural, and electrical characterization of single-crystalline iron pyrite (FeS₂) nanorods, nanobelts, and nanoplates synthesized via sulfidation reaction with iron dichloride (FeCl₂) and iron dibromide (FeBr₂). The as-synthesized products were confirmed to be single-crystal phase pure cubic iron pyrite using powder X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. An intermediate reaction temperature of 425 °C or a high sulfur vapor pressure under high temperatures was found to be critical for the formation of phase pure pyrite. Field effect transport measurements showed that these pyrite nanostructures appear to behave as a moderately p-doped semiconductor with an average resistivity of 2.19 ± 1.21 Ω·cm, an improved hole mobility of 0.2 cm² V⁻¹ s⁻¹, and a lower carrier concentration on the order of 10¹⁸-10¹⁹ cm⁻³ compared with previous reported pyrite nanowires. Temperature-dependent electrical transport measurements reveal Mott variable range hopping transport in the temperature range 40-220 K and transport via thermal activation of carriers with an activation energy of 100 meV above room temperature (300-400 K). Most importantly, the transport properties of the pyrite nanodevices do not change if highly pure (99.999%) precursors are utilized, suggesting that the electrical transport is dominated by intrinsic defects in pyrite. These single-crystal pyrite nanostructures are nice platforms to further study the carrier conduction mechanisms, semiconductor defect physics, and surface properties in depth, toward improving the physical properties of pyrite for efficient solar energy conversion.

  5. Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures.

    PubMed

    Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

    2011-09-01

    The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

  6. Solvothermal synthesis of TiO2 nanocrystals with {001} facets using titanic acid nanobelts for superior photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Cao, Yuhui; Zong, Lanlan; Li, Qiuye; Li, Chen; Li, Junli; Yang, Jianjun

    2017-01-01

    Anatase TiO2 nanocrystals exposed with {001} facets were fabricated by solvothermal strategy in HF-C4H9OH mixed solution, using titanic acid nanobelts (TAN) as a precursor. The shape of TAN is a long flat plane with a high aspect ratio, and F- is easily adsorbed on the surface of the nanobelts, inducing a higher exposure of {001} facet of TiO2 nanoparticles during the structure reorganization. The exposed percentage of {001} facets could vary from 40 to 77% by adjusting the amount of HF. The as-prepared samples were characterized by transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscope. The photocatalytic measurement showed that TiO2 nanocrystals with 77% {001} facets exhibited much superior photocatalytic activity for photodegradation of methyl orange, methylene blue, and rhodamine B. And what's more, the mineralization rate of methyl orange was as high as 96% within 60 min. The photocatalytic enhancement is due to a large amount of the high energetic {001} facets exposing, the special truncated octahedral morphology and a stronger ability for dyes adsorption.

  7. High-performance ultraviolet photodetectors based on solution-grown ZnS nanobelts sandwiched between graphene layers

    PubMed Central

    Kim, Yeonho; Kim, Sang Jin; Cho, Sung-Pyo; Hong, Byung Hee; Jang, Du-Jeon

    2015-01-01

    Ultraviolet (UV) light photodetectors constructed from solely inorganic semiconductors still remain unsatisfactory because of their low electrical performances. To overcome this limitation, the hybridization is one of the key approaches that have been recently adopted to enhance the photocurrent. High-performance UV photodetectors showing stable on-off switching and excellent spectral selectivity have been fabricated based on the hybrid structure of solution-grown ZnS nanobelts and CVD-grown graphene. Sandwiched structures and multilayer stacking strategies have been applied to expand effective junction between graphene and photoactive ZnS nanobelts. A multiply sandwich-structured photodetector of graphene/ZnS has shown a photocurrent of 0.115 mA under illumination of 1.2 mWcm−2 in air at a bias of 1.0 V, which is higher 107 times than literature values. The multiple-sandwich structure of UV-light sensors with graphene having high conductivity, flexibility, and impermeability is suggested to be beneficial for the facile fabrication of UV photodetectors with extremely efficient performances. PMID:26197784

  8. TiO{sub 2} nanobelts photocatalysts decorated with Bi{sub 2}WO{sub 6} nanocrystals: Preparation and enhanced photocatalytic activity

    SciTech Connect

    Li, Yang; Wu, Wenjian; Wu, Mingzai; Dai, Peng; Zhang, Lili; Sun, Zhaoqi; Li, Guang; Liu, Xiansong; Chen, Xiaoshuang; Zheng, Xiuwen

    2014-07-01

    Highlights: • TiO{sub 2} nanobelts decorated with Bi{sub 2}WO{sub 6} nanocrystals have been prepared. • The introduction of Bi{sub 2}WO{sub 6} nanocrystals can induce red-shift of absorption edge. • The Bi{sub 2}WO{sub 6}/TiO{sub 2} composites show higher photocatalytic activity than TiO{sub 2} nanobelts. • The Bi{sub 2}WO{sub 6}/TiO{sub 2} composites have long-time recyclable ability of photodegradation. - Abstract: In this paper, the controllable preparation of one-dimensional TiO{sub 2} nanobelts decorated with Bi{sub 2}WO{sub 6} nanocrystals based on Ti foils was reported using two-step hydrothermal treatment method. X-ray photoelectron spectroscopy measurement results exhibited the binding energy changes of Ti and O elements, implying the strong adhesion of Bi{sub 2}WO{sub 6} nanocrystals onto the surface of TiO{sub 2} nanobelts. The ultraviolet–visible (UV–vis) absorption spectra showed that the introduction of Bi{sub 2}WO{sub 6} nanocrystals could induce the red-shift of absorption edge and exhibited a broad absorption band in the visible region, which extended the scope of absorption spectrum and help to improve the photocatalytic degradation efficiency. The photocatalytic experiment results revealed that Bi{sub 2}WO{sub 6}/TiO{sub 2} composites possess higher photocatalytic activities toward methyl orange than pure TiO{sub 2} nanobelts. The degradation efficiency of 90% after 5 cycles indicated that the as-prepared composite photocatalysts exhibited excellent long-time recyclable ability for the degradation of contaminants.

  9. Fe(NO3)3-assisted large-scale synthesis of Si3N4 nanobelts from quartz and graphite by carbothermal reduction–nitridation and their photoluminescence properties

    PubMed Central

    Liu, Shuyue; Fang, Minghao; Huang, Zhaohui; Huang, Juntong; Ji, Haipeng; Liu, Haitao; Liu, Yan-gai; Wu, Xiaowen

    2015-01-01

    The large-scale synthesis of Si3N4 nanobelts from quartz and graphite on a graphite-felt substrate was successfully achieved by catalyst-assisted carbothermal reduction–nitridation. The phase composition, morphology, and microstructure of Si3N4 nanobelts were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The Si3N4 nanobelts were ~4–5 mm long and ~60 nm thick and exhibited smooth surfaces and flexible shapes. The Si3N4 nanobelts were well crystallized and grow along the [101] direction. The growth is dominated by the combined mechanisms of vapor–liquid–solid base growth and vapor–solid tip growth. The Fe(NO3)3 played a crucial role in promoting the nanobelt formation in the initial stage. The room-temperature photoluminescence spectrum of Si3N4 nanobelts consists of three emission peaks centered at 413, 437, and 462 nm, indicating potential applications in optoelectronic nanodevices. PMID:25757903

  10. Measuring suspended sediment: Chapter 10

    USGS Publications Warehouse

    Gray, J.R.; Landers, M.N.

    2013-01-01

    Suspended sediment in streams and rivers can be measured using traditional instruments and techniques and (or) surrogate technologies. The former, as described herein, consists primarily of both manually deployed isokinetic samplers and their deployment protocols developed by the Federal Interagency Sedimentation Project. They are used on all continents other than Antarctica. The reliability of the typically spatially rich but temporally sparse data produced by traditional means is supported by a broad base of scientific literature since 1940. However, the suspended sediment surrogate technologies described herein – based on hydroacoustic, nephelometric, laser, and pressure difference principles – tend to produce temporally rich but in some cases spatially sparse datasets. The value of temporally rich data in the accuracy of continuous sediment-discharge records is hard to overstate, in part because such data can often overcome the shortcomings of poor spatial coverage. Coupled with calibration data produced by traditional means, surrogate technologies show considerable promise toward providing the fluvial sediment data needed to increase and bring more consistency to sediment-discharge measurements worldwide.

  11. 7 CFR 1221.30 - Suspend.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.30 Suspend....

  12. 7 CFR 1221.30 - Suspend.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.30 Suspend....

  13. 7 CFR 1221.30 - Suspend.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.30 Suspend....

  14. 7 CFR 1221.30 - Suspend.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.30 Suspend....

  15. 7 CFR 1221.30 - Suspend.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.30 Suspend....

  16. 7 CFR 1218.20 - Suspend.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.20 Suspend....

  17. 7 CFR 1218.20 - Suspend.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.20 Suspend....

  18. 7 CFR 1218.20 - Suspend.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.20 Suspend....

  19. 7 CFR 1218.20 - Suspend.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.20 Suspend....

  20. 7 CFR 1218.20 - Suspend.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.20 Suspend....

  1. 7 CFR 1216.27 - Suspend.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.27 Suspend....

  2. 7 CFR 1216.27 - Suspend.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.27 Suspend....

  3. 7 CFR 1216.27 - Suspend.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.27 Suspend....

  4. 7 CFR 1216.27 - Suspend.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.27 Suspend....

  5. 7 CFR 1216.27 - Suspend.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.27 Suspend....

  6. 7 CFR 1280.124 - Suspend.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.124 Suspend....

  7. Diffusiophoretic Focusing of Suspended Colloids

    NASA Astrophysics Data System (ADS)

    Shi, Nan; Nery-Azevedo, Rodrigo; Abdel-Fattah, Amr I.; Squires, Todd M.

    2016-12-01

    Using a microfluidic system to impose and maintain controlled, steady-state multicomponent p H and electrolyte gradients, we present systems where the diffusiophoretic migration of suspended colloids leads them to focus at a particular position, even in steady-state gradients. We show that naively superpositing effects of each gradient may seem conceptually and qualitatively reasonable, yet is invalid due to the coupled transport of these multicomponent electrolytes. In fact, reformulating the classic theories in terms of the flux of each species (rather than local gradients) reveals rather stringent conditions that are necessary for diffusiophoretic focusing in steady gradients. Either particle surface properties must change as a function of local composition in solution (akin to isoelectric focusing in electrophoresis), or chemical reactions must occur between electrolyte species, for such focusing to be possible. The generality of these findings provides a conceptual picture for understanding, predicting, or designing diffusiophoretic systems.

  8. Few-layered MoS2 nanosheets wrapped ultrafine TiO2 nanobelts with enhanced photocatalytic property

    NASA Astrophysics Data System (ADS)

    Li, Haidong; Wang, Yana; Chen, Guohui; Sang, Yuanhua; Jiang, Huaidong; He, Jiating; Li, Xu; Liu, Hong

    2016-03-01

    Photocatalytic materials comprised of semiconductor nanostructures have attracted tremendous scientific and technological interest over the last 30 years. This is due to the fact that these photocatalytic materials have unique properties that allow for an effective direct energy transfer from light to highly reactive chemical species which are applicable in the remediation of environmental pollutants and photocatalytic hydrogen generation. Heterostructured photocatalysts are a promising type of photocatalyst which can combine the properties of different components to generate a synergic effect, resulting in a high photocatalytic activity. In this work, a heterostructured photocatalyst comprised of few-layered MoS2 nanosheets coated on a TiO2 nanobelts surface was synthesized through a simple hydrothermal treatment. The hybrid heterostructures with enhanced broad spectrum photocatalytic properties can harness UV and visible light energy to decompose organic contaminants in aqueous solutions as well as split water to hydrogen and oxygen. The mechanism of the enhancement is that the MoS2/TiO2 nanobelts heterostructure can enhance the separation of the photo-induced carriers, which results in a higher photocurrent due to the special electronic characteristics of the graphene-like layered MoS2 nanosheets. This methodology is potentially applicable to the synthesis of a range of hybrid nanostructures with promising applications in photocatalysis and other relevant areas.Photocatalytic materials comprised of semiconductor nanostructures have attracted tremendous scientific and technological interest over the last 30 years. This is due to the fact that these photocatalytic materials have unique properties that allow for an effective direct energy transfer from light to highly reactive chemical species which are applicable in the remediation of environmental pollutants and photocatalytic hydrogen generation. Heterostructured photocatalysts are a promising type of

  9. 5 CFR 919.1010 - Suspending official.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Suspending official. 919.1010 Section 919.1010 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS... official. (a) Suspending official means an agency official who is authorized to impose suspension....

  10. Suspending and Reinstating Joint Activities with Dialogue

    ERIC Educational Resources Information Center

    Chevalley, Eric; Bangerter, Adrian

    2010-01-01

    Interruptions are common in joint activities like conversations. Typically, interrupted participants suspend the activity, address the interruption, and then reinstate the activity. In conversation, people jointly commit to interact and to talk about a topic, establishing these commitments sequentially. When a commitment is suspended, face is…

  11. 30 CFR 56.9317 - Suspended loads.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Suspended loads. 56.9317 Section 56.9317 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... § 56.9317 Suspended loads. Persons shall not work or pass under the buckets or booms of loaders...

  12. 30 CFR 56.9317 - Suspended loads.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Suspended loads. 56.9317 Section 56.9317 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... § 56.9317 Suspended loads. Persons shall not work or pass under the buckets or booms of loaders...

  13. 30 CFR 56.9317 - Suspended loads.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Suspended loads. 56.9317 Section 56.9317 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... § 56.9317 Suspended loads. Persons shall not work or pass under the buckets or booms of loaders...

  14. 30 CFR 56.9317 - Suspended loads.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Suspended loads. 56.9317 Section 56.9317 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... § 56.9317 Suspended loads. Persons shall not work or pass under the buckets or booms of loaders...

  15. 30 CFR 56.9317 - Suspended loads.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Suspended loads. 56.9317 Section 56.9317 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... § 56.9317 Suspended loads. Persons shall not work or pass under the buckets or booms of loaders...

  16. Probing microstructure and phase evolution of α-MoO3 nanobelts for sodium-ion batteries by in situ transmission electron microscopy

    DOE PAGES

    Xia, Weiwei; Xu, Feng; Zhu, Chongyang; ...

    2016-07-15

    The fundamental electrochemical reaction mechanisms and the phase transformation pathways of layer-structured α-MoO3 nanobelt during the sodiation/desodiation process to date remain largely unknown. In this study, to observe the real-time sodiation/desodiaton behaviors of α-MoO3 during electrochemical cycling, we construct a MoO3 anode sodium-ion battery inside a transmission electron microscope (TEM). Utilizing in situ TEM and electron diffraction pattern (EDP) observation, α-MoO3 nanobelts are found to undergo a unique multi-step phase transformation. Upon the first sodiation, α-MoO3 nanobelts initially form amorphous NaxMoO3 phase and are subsequently sodiated into intermediate phase of crystalline NaMoO2, finally resulting in the crystallized Mo nanograins embeddedmore » within the Na2O matrix. During the first desodiation process, Mo nanograins are firstly re-oxidized into intermediate phase NaMoO2 that is further transformed into amorphous Na2MoO3, resulting in an irreversible phase transformation. Upon subsequent sodiation/desodiation cycles, however, a stable and reversible phase transformation between crystalline Mo and amorphous Na2MoO3 phases has been revealed. In conclusion, our work provides an in-deepth understanding of the phase transformation pathways of α-MoO3 nanobelts upon electrochemical sodiation/desodiation processes, with the hope of assistance in designing sodium-ion batteries with enhanced performance.« less

  17. A novel 3D structure composed of strings of hierarchical TiO{sub 2} spheres formed on TiO{sub 2} nanobelts with high photocatalytic properties

    SciTech Connect

    Jiang, Yongjian; Li, Meicheng; Song, Dandan; Li, Xiaodan; Yu, Yue

    2014-03-15

    A novel hierarchical titanium dioxide (TiO{sub 2}) composite nanostructure with strings of anatase TiO{sub 2} hierarchical micro-spheres and rutile nanobelts framework (TiO{sub 2} HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO{sub 2} nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m{sup 2}/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO{sub 2} HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO{sub 2} may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries. -- Graphical abstract: Novel TiO{sub 2} with anatase micro-spheres and rutile nanobelts is synthesized. Enhanced photocatalysis is attributed to hierarchical structures (3D spheres), conductive channel (1D nanobelts) and large specific surface area (2D nanosheet). Highlights: • The novel TiO{sub 2} nanostructure (HSN) is fabricated for the first time. • HSN is composed of strings of anatase hierarchical spheres and rutile nanobelt. • HSN presents a larger S{sub BET} of 191 m{sup 2}/g, 3 times larger than the Degussa P25 (59 m{sup 2}/g). • HSN owns three kinds of dimensional TiO{sub 2} (1D, 2D and 3D) simultaneously. • HSN exhibits better photocatalytic performance compared with Degussa P25.

  18. Organic solvent-induced controllable crystallization of the inorganic salt Na3[Au(SO3)2] into ultralong nanobelts and hierarchical microstructures of nanowires

    NASA Astrophysics Data System (ADS)

    Liu, Sen; Tian, Jingqi; Wang, Lei; Li, Hailong; Sun, Xuping

    2011-04-01

    The present paper reports an organic solvent-induced controllable crystallization of a water-soluble inorganic salt Na3[Au(SO3)2] into ultralong nanobelts and hierarchical microstructures of one-dimensional (1D) nanowires. It was found that the morphology of the resulting crystals can be fine tuned by simply varying the experimental parameters, such as the ratios of water to organic solvent and gold salt to organic solvent, as well as the type of organic solvent.The present paper reports an organic solvent-induced controllable crystallization of a water-soluble inorganic salt Na3[Au(SO3)2] into ultralong nanobelts and hierarchical microstructures of one-dimensional (1D) nanowires. It was found that the morphology of the resulting crystals can be fine tuned by simply varying the experimental parameters, such as the ratios of water to organic solvent and gold salt to organic solvent, as well as the type of organic solvent. Electronic supplementary information (ESI) available: EDS and XRD analysis of nanobelts. See DOI: 10.1039/c0nr00690d

  19. Synthesis of scaly Sn3O4/TiO2 nanobelt heterostructures for enhanced UV-visible light photocatalytic activity.

    PubMed

    Chen, Guohui; Ji, Shaozheng; Sang, Yuanhua; Chang, Sujie; Wang, Yana; Hao, Pin; Claverie, Jerome; Liu, Hong; Yu, Guangwei

    2015-02-21

    A novel scaly Sn3O4/TiO2 nanobelt heterostructured photocatalyst was fabricated via a facile hydrothermal route. The scaly Sn3O4 nanoflakes can be synthesized in situ and assembled on surface coarsened TiO2 nanobelts through a hydrothermal process. The morphology and distribution of Sn3O4 nanoflakes can be well-controlled by simply tuning the Sn/Ti molar ratio of the reactants. Compared with single phase nanostructures of Sn3O4 and TiO2, the scaly hybrid nanobelts exhibited markedly enhanced photoelectrochemical (PEC) response, which caused higher photocatalytic hydrogen evolution even without the assistance of Pt as a co-catalyst, and enhanced the degradation ability of organic pollutants under both UV and visible light irradiation. In addition to the increased exposure of active facets and broad light absorption, the outstanding performance is ascribed to the matching energy band structure between Sn3O4 and TiO2 at the two sides of the heterostructure, which efficiently reduces the recombination of photo-excited electron-hole pairs and prolongs the lifetime of charge carriers. Both photocatalytic assessment and PEC tests revealed that Sn3O4/TiO2 heterostructures with a molar ratio of Sn/Ti of 2/1 exhibited the highest photocatalytic activity. This study provides a facile and low-cost method for the large scale production of Sn3O4 based materials in various applications.

  20. Synthesis of few-layer MoS2 nanosheet-coated TiO2 nanobelt heterostructures for enhanced photocatalytic activities.

    PubMed

    Zhou, Weijia; Yin, Zongyou; Du, Yaping; Huang, Xiao; Zeng, Zhiyuan; Fan, Zhanxi; Liu, Hong; Wang, Jiyang; Zhang, Hua

    2013-01-14

    MoS(2) nanosheet-coated TiO(2) nanobelt heterostructures--referred to as TiO(2)@MoS(2)--with a 3D hierarchical configuration are prepared via a hydrothermal reaction. The TiO(2) nanobelts used as a synthetic template inhibit the growth of MoS(2) crystals along the c-axis, resulting in a few-layer MoS(2) nanosheet coating on the TiO(2) nanobelts. The as-prepared TiO(2)@MoS(2) heterostructure shows a high photocatalytic hydrogen production even without the Pt co-catalyst. Importantly, the TiO(2)@MoS(2) heterostructure with 50 wt% of MoS(2) exhibits the highest hydrogen production rate of 1.6 mmol h(-1) g(-1). Moreover, such a heterostructure possesses a strong adsorption ability towards organic dyes and shows high performance in photocatalytic degradation of the dye molecules.

  1. Shenzhen: city of suspended possibility.

    PubMed

    Bach, Jonathan

    2011-01-01

    This essay on Shenzhen, China, presents three vignettes addressing the question of home in a city of migrants. The first section explores the ubiquitous narratives of success forming the city's foundational myth. The second follows this myth into the world of a Shenzhen filmmaker and his characters, as they navigate the tension between the idea of home and the urge to start anew, resulting in the suspended possibility of the title. The last section looks at young architects who hope to preserve the city's heterotopic sites of migrants and original villagers through architectural innovations. The cases show how an economy of desire supplements the political economy of this export-driven city. The city appears as an urban desiring machine that produces itself as an object of desire for the migrants of all classes who flock to its factories, "urban villages", white-collar jobs, luxury villas and underground economy. The essay is an encounter with the mythology of success and failure, the intertwining of home as an end and home as the beginning, and with the manipulation of space that allows residents to control their own subjectivity.

  2. Optimization of Deposition Process and Microscopic Characterization of Highly Oriented Aluminum Nitride Thin Films for Bimorph Structures of Piezoelectric Tunable Capacitors

    NASA Astrophysics Data System (ADS)

    Nagano, Toshihiko; Nishigaki, Michihiko; Itaya, Kazuhiko; Kawakubo, Takashi

    2009-02-01

    Film deposition with RF sputtering to control residual stress in aluminum nitride (AlN) thin films has been investigated to fabricate the bimorph actuator for a piezoelectric tunable capacitor with low-voltage operation. The effects of conditions in sputtering and surface cleaning were studied both to obtain a preferable film orientation for piezoelectric actuation and to suppress structural deformation of the cantilever due to the residual stress in films. Microscopic analysis revealed that (0001)-oriented AlN and (111)-oriented Al films were epitaxially grown at each interface in the bimorph structure. The current-voltage (I-V) measurements showed a leakage current of less than 5 ×10-5 A m-2 in 500-nm thick AlN films up to 30 V. The effect of optimization of process parameters was demonstrated by the capacitance-voltage (C-V) characteristics of the folded-beam tunable capacitor, in which the suppression of residual stress in piezoelectric layers was shown to be effective to obtain low-voltage operation.

  3. Pre-stressed piezoelectric bimorph micro-actuators based on machined 40 µm PZT thick films: batch scale fabrication and integration with MEMS

    NASA Astrophysics Data System (ADS)

    Wilson, S. A.; Jourdain, R. P.; Owens, S.

    2010-09-01

    The projected force-displacement capability of piezoelectric ceramic films in the 20-50 µm thickness range suggests that they are well suited to many micro-fluidic and micro-pneumatic applications. Furthermore when they are configured as bending actuators and operated at ~ 1 V µm - 1 they do not necessarily conform to the high-voltage, very low-displacement piezoelectric stereotype. Even so they are rarely found today in commercial micro-electromechanical devices, such as micro-pumps and micro-valves, and the main barriers to making them much more widely available would appear to be processing incompatibilities rather than commercial desirability. In particular, the issues associated with integration of these devices into MEMS at the production level are highly significant and they have perhaps received less attention in the mainstream than they deserve. This paper describes a fabrication route based on ultra-precision ceramic machining and full-wafer bonding for cost-effective batch scale production of thick film PZT bimorph micro-actuators and their integration with MEMS. The resulting actuators are pre-stressed (ceramic in compression) which gives them added performance, they are true bimorphs with bi-directional capability and they exhibit full bulk piezoelectric ceramic properties. The devices are designed to integrate with ancillary systems components using transfer-bonding techniques. The work forms part of the European Framework 6 Project 'Q2M—Quality to Micro'.

  4. Satellite power using magnetically suspended flywheel stack

    NASA Technical Reports Server (NTRS)

    Kirk, James A.; Anand, Davinder K.

    1987-01-01

    Research activities with magnetically suspended flywheels are reported. The purpose of the effort is to critically examine and further the development of all the key technologies which impact the inertial energy storage system. The results presented discuss the concept of a magnetically suspended flywheel as it applies to a 500 Watt-hour energy storage system. The proposed system is currently under hardware development and is based upon two pancake magnetic bearings arranged in a vertical stack.

  5. Stability of suspended graphene under Casimir force

    NASA Astrophysics Data System (ADS)

    Chudnovsky, E. M.; Zarzuela, R.

    2016-08-01

    We consider a graphene sheet suspended above a conducting surface. Treating graphene as an elastic membrane subjected to Casimir force, we study its stability against sagging towards the conductor. There exists a critical elevation at the edges below which the central part of the suspended graphene nucleates a trunk that sinks under the action of the Casimir force. The dependence of the critical elevation on temperature, dimensions, and the elastic stress applied to the graphene sheet is computed.

  6. [Suspended particulates and lung health].

    PubMed

    Neuberger, Manfred; Moshammer, Hanns

    2004-01-01

    Based on several severe air pollution episodes, a temporal correlation between high concentrations of particulate matter (PM) and SO2 pollution and acute increases in respiratory and cardiopulmonary mortality had been established in Vienna for the 1970's. After air pollution had decreased in Austria in the 1980's--as documented by data on SO2, and total suspended particles (TSP)--no such associations between day-to-day changes of SO2 and TSP and mortality have been documented any more, however, traffic related pollutants like fine particles and NO2 remained a problem. Therefore, short term effects of PM on lung function, morbidity and mortality were investigated in Vienna, Linz, Graz and a rural control area. Long-term exposure and chronic disease--even more important for public health--were studied in repeated cross-sectional, a mixed longitudinal and a birth cohort study on school children in the city of Linz. Lung function growth was found impaired from long-term exposure to air pollutants and improved in districts where ambient air pollution had decreased. Where only TSP and SO2 had decreased, no continuous improvement of small airway function was found and end-expiratory flow rates stayed impaired where NO2-reduction from technical improvements of cars and industry was counterbalanced by increase of motorized (diesel) traffic. Remaining acute effects of ambient air pollution in 2001 from PM, NO2 and co-pollutants found in a time series study also show that continuing efforts are necessary. Active surface of particles inhaled several hours to days before spirometry was found related to short-term reductions in forced vital capacity-FVC (p<0.01), forced expiratory volume in one second-FEV1 (p<0.01) and maximal expiratory flow rate at 50% of vital capacity-MEF50 (p<0.05). In pupils with asthma or previous airway obstruction 4-week-diaries proved that the following symptoms increased with acute exposure to higher active surface of particles: wheezing (p<0

  7. Facile conversion of silicon nitride nanobelts into sandwich-like nanosaws II: growth mechanism and optical properties

    NASA Astrophysics Data System (ADS)

    Guo, Gang Feng; He, Mingsheng; Kong, Xiang Yang; Lin, Hong; Li, Jianbao; Fan, Li-Zhen

    2010-02-01

    In a previous paper (G.F. Guo et al., Appl. Phys. A, 2009), the microstructures of sandwich-like nanosaws have been revealed clearly. Here, the growth mechanism and optical properties of Si3N4 sandwich-like nanosaws were further investigated. It is assumed that the growth atmosphere with a large amount of *N (active nitrogen) from the decomposition of NH3 would be the key factor for the formation of sandwich-like nanosaws during the catalyst-assisted pyrolysis of the polymeric precursors. From the characterizations of TEM together with the systematic composition analysis, we found that a large excess of nitrogen element occurred in the central “soldering” region as well as high density defects, which induced the asymmetric growth of nanoteeth on the original nanobelt sidewall, forming into a sandwich-like nanosaw morphology. The unique optical properties of sandwich-like nanosaws could be attributed from the presence of a large amount of nitrogen dangling bond defects in the central “soldering” region, and a new optical band-gap model was proposed for the interpretation of the photoluminescence spectra.

  8. Self-powered flexible and transparent photovoltaic detectors based on CdSe nanobelt/graphene Schottky junctions.

    PubMed

    Gao, Zhiwei; Jin, Weifeng; Zhou, Yu; Dai, Yu; Yu, Bin; Liu, Chu; Xu, Wanjin; Li, Yanping; Peng, Hailin; Liu, Zhongfan; Dai, Lun

    2013-06-21

    Flexible and transparent electronic and optoelectronic devices have attracted more and more research interest due to their potential applications in developing portable, wearable, low-cost, and implantable devices. We have fabricated and studied high-performance flexible and transparent CdSe nanobelt (NB)/graphene Schottky junction self-powered photovoltaic detectors for the first time. Under 633 nm light illumination, typical photosensitivity and responsivity of the devices are about 1.2 × 10(5) and 8.7 A W(-1), respectively. Under 3500 Hz switching frequency, the response and recovery times of them are about 70 and 137 μs, respectively, which, to the best of our knowledge, are the best reported values for nanomaterial based Schottky junction photodetectors up to date. The detailed properties of the photodetectors, such as the influences of incident light wavelength and light intensity on the external quantum efficiency and speed, are also investigated. Detailed discussions are made in order to understand the observed phenomena. Our work demonstrates that the self-powered flexible and transparent CdSe NB/graphene Schottky junction photovoltaic detectors have a bright application prospect.

  9. Size and Temperature Dependence of Electron Transfer between CdSe Quantum Dots and a TiO 2 Nanobelt

    DOE PAGES

    Tafen, De Nyago; Prezhdo, Oleg V.

    2015-02-24

    Understanding charge transfer reactions between quantum dots (QD) and metal oxides is fundamental for improving photocatalytic, photovoltaic and electronic devices. The complexity of these processes makes it difficult to find an optimum QD size with rapid charge injection and low recombination. We combine time-domain density functional theory with nonadiabatic molecular dynamics to investigate the size and temperature dependence of the experimentally studied electron transfer and charge recombination at CdSe QD-TiO2 nanobelt (NB) interfaces. The electron injection rate shows strong dependence on the QD size, increasing for small QDs. The rate exhibits Arrhenius temperature dependence, with the activation energy of themore » order of millielectronvolts. The charge recombination process occurs due to coupling of the electronic subsystem to vibrational modes of the TiO2 NB. Inelastic electron-phonon scattering happens on a picosecond time scale, with strong dependence on the QD size. Our simulations demonstrate that the electron-hole recombination rate decreases significantly as the QD size increases, in excellent agreement with experiments. The temperature dependence of the charge recombination rates can be successfully modeled within the framework of the Marcus theory through optimization of the electronic coupling and the reorganization energy. Our simulations indicate that by varying the QD size, one can modulate the photoinduced charge separation and charge recombination, fundamental aspects of the design principles for high efficiency devices.« less

  10. High-performance single CdS nanowire (nanobelt) Schottky junction solar cells with Au/graphene Schottky electrodes.

    PubMed

    Ye, Yu; Dai, Yu; Dai, Lun; Shi, Zujin; Liu, Nan; Wang, Fei; Fu, Lei; Peng, Ruomin; Wen, Xiaonan; Chen, Zhijian; Liu, Zhongfan; Qin, Guogang

    2010-12-01

    High-performance single CdS nanowire (NW) as well as nanobelt (NB) Schottky junction solar cells were fabricated. Au (5 nm)/graphene combined layers were used as the Schottky contact electrodes to the NWs (NBs). Typical as-fabricated NW solar cell shows excellent photovoltaic behavior with an open circuit voltage of ∼0.15 V, a short circuit current of ∼275.0 pA, and an energy conversion efficiency of up to ∼1.65%. The physical mechanism of the combined Schottky electrode was discussed. We attribute the prominent capability of the devices to the high-performance Schottky combined electrode, which has the merits of low series resistance, high transparency, and good Schottky contact to the CdS NW (NB). Besides, a promising site-controllable patterned graphene transfer method, which has the advantages of economizing graphene material and free from additional etching process, was demonstrated in this work. Our results suggest that semiconductor NWs (NBs) are promising materials for novel solar cells, which have potential application in integrated nano-optoelectronic systems.

  11. Suspended two-dimensional electron and hole gases

    SciTech Connect

    Kazazis, D.; Bourhis, E.; Gierak, J.; Gennser, U.; Bourgeois, O.; Antoni, T.

    2013-12-04

    We report on the fabrication of fully suspended two-dimensional electron and hole gases in III-V heterostructures. Low temperature transport measurements verify that the properties of the suspended gases are only slightly degraded with respect to the non-suspended gases. Focused ion beam technology is used to pattern suspended nanostructures with minimum damage from the ion beam, due to the small width of the suspended membrane.

  12. Fabrication of V2O3/C core-shell structured composite and VC nanobelts by the thermal treatment of VO2/C composite

    NASA Astrophysics Data System (ADS)

    Zhang, Yifu; Fan, Meijuan; Hu, Ling; Wu, Weibing; Zhang, Juecheng; Liu, Xinghai; Zhong, Yalan; Huang, Chi

    2012-10-01

    Belt-like V2O3 encapsulated into carbon tubes (V2O3/C) core-shell structured composite and vanadium carbide (VC) nanobelts have been successfully synthesized by the thermal treatment with VO2/C core-shell structured composite through adjusting the heating temperature for the first time. The amorphous carbon on the surface of VO2 plays a dual role in this thermal process, namely as the reductant to reduce VO2 to V2O3 or VC, and as the carbon precursor for the V2O3/C carbon shell and VC. The as-obtained samples were respectively characterized by X-ray powder diffraction, energy-dispersive X-ray spectrometer, Raman spectrum, elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller. V2O3/C was successfully synthesized at 700-900 °C for 2 h, and VC nanobelts were successfully prepared at 1000 °C for 2 h. The as-obtained V2O3/C composite and VC nanobelts contain C-H groups, which will facilitate the linkage of catalytic species or polymers to the surface in their potential applications. V2O3/C composite has higher specific surface area than that of VC due to the amorphous carbon coated on the surface of V2O3. Furthermore, the thermal stability of VC in air was investigated by Thermo-Gravimetric/Differential Thermal Analyzer, revealing that it had good thermal stability and oxidation resistance below 335 °C in air.

  13. Suspending superconducting qubits by silicon micromachining

    NASA Astrophysics Data System (ADS)

    Chu, Y.; Axline, C.; Wang, C.; Brecht, T.; Gao, Y. Y.; Frunzio, L.; Schoelkopf, R. J.

    2016-09-01

    We present a method for relieving aluminum 3D transmon qubits from a silicon substrate using micromachining. Our technique is a high yield, one-step deep reactive ion etch that requires no additional fabrication processes and results in the suspension of the junction area and edges of the aluminum film. The drastic change in the device geometry affects both the dielectric and the flux noise environment experienced by the qubit. In particular, the participation ratios of various dielectric interfaces are significantly modified, and suspended qubits exhibited longer T1's than non-suspended ones. We also find that the suspension increases the flux noise experienced by tunable SQUID-based qubits.

  14. Polymer microlasers with a suspended cavity design

    NASA Astrophysics Data System (ADS)

    Vanga, Sudheer Kumar; Nalla, Venkatram; Bettiol, Andrew A.

    2015-04-01

    We report on the fabrication of microlasers with suspended cavity design in a thin layer of Rhodamine B doped SU-8 polymer using proton beam writing. Optical characterization of the fabricated three-dimensional microlasers under ambient atmosphere results in low lasing threshold of 0.5 μJ/mm2, which is an improvement by factor of 2 when compared to planar microlasers. The directional behavior is also observed in whispering gallery mode microlasers with spiral cavity design. These microlasers with suspended cavity design are not only useful in reducing the lasing threshold but also have significance in 3D photonic integrated circuits.

  15. A Successful Retention Program for Suspended Students

    ERIC Educational Resources Information Center

    Dill, Anna L.; Gilbert, Jerome A.; Hill, Jennifer P.; Minchew, Sue S.; Sempier, Tracie A.

    2011-01-01

    Traditionally at Mississippi State University (MSU), students who are placed on academic suspension are required to stay out of school one regular semester. As an alternative, the university designed a program for early readmission for suspended students who agree to follow the requirements outlined in the "Learning Skills Support…

  16. Size of Suspended Sediment Over Dunes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Samples of suspended sediment were collected at four elevations simultaneously over two-dimensional mobile dunes in 0.5 mm sand in a laboratory flume channel. A constant sampling position relative to the dunes was maintained by adjusting the translation rate of the sampling carriage to be the same ...

  17. Size of Suspended Sediment over Dunes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Samples of suspended sediment were collected at four elevations simultaneously over two-dimensional mobile dunes in two mixtures of 0.5 mm sand in a laboratory flume channel. A constant sampling position relative to the dunes was maintained by adjusting the translation rate of the sampling carriage...

  18. 7 CFR 1212.28 - Suspend.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS..., PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion, Consumer Education, and Industry Information Order Definitions § 1212.28 Suspend. “Suspend” means to...

  19. The transport of 'suspended' sediment by water

    NASA Astrophysics Data System (ADS)

    Parsons, Anthony; Cooper, James; Wainwright, John; Sekiguichi, Tomohiro

    2013-04-01

    Coherent turbulent flow structures, such as eddy-like, macro-turbulent structures and smaller scale bursting events, cause a two-way vertical exchange of momentum between the sediment bed and the water surface. Thus movement of suspended particles in open channel flows has a strong correlation with the advection and propagation of these turbulent flow structures, controlling entrainment , travel and deposition. Consequently, there is an argument in favour of the view that suspended sediment merely travels in suspension, but that its distance of travel is finite, and that between periods of travel it is at rest on the bed of the river. To test his hypothesis we added 25 kg of fluorescent sand, fine enough to be transported in suspension, into a steady flow discharge of 0.95 cumecs in the 160-m-long flume at Tsukuba University. After the flow event, a few grains of the sand were identified less than 5 m from the point of introduction and progressively (but irregularly) more downflume. Although our results are both limited and preliminary due to the nature of the existing flume, they clearly show that suspended sediment has a virtual velocity that is less than that of the flow in which the sediment is suspended. For the sediment-size range and flow velocity used in our experiment this virtual velocity is of the order of 50% of the water velocity.

  20. N-Doped TiO2 Nanobelts with Coexposed (001) and (101) Facets and Their Highly Efficient Visible-Light-Driven Photocatalytic Hydrogen Production.

    PubMed

    Sun, Shuchao; Gao, Peng; Yang, Yurong; Yang, Piaoping; Chen, Yujin; Wang, Yanbo

    2016-07-20

    To narrow the band gap (3.2 eV) of TiO2 and extend its practical applicability under sunlight, the doping with nonmetal elements has been used to tune TiO2 electronic structure. However, the doping also brings new recombination centers among the photoinduced charge carriers, which results in a quantum efficiency loss accordingly. It has been proved that the {101} facets of anatase TiO2 are beneficial to generating and transmitting more reductive electrons to promote the H2-evolution in the photoreduction reaction, and the {001} facets exhibit a higher photoreactivity to accelerate the reaction involved of photogenerated hole. Thus, it was considered by us that using the surface heterojunction composed of both {001} and {101} facets may depress the disadvantage of N doping. Fortunately, we successfully synthesized anatase N-doped TiO2 nanobelts with a surface heterojunction of coexposed (101) and (001) facets. As expected, it realized the charge pairs' spatial separation and showed higher photocatalytic activity under a visible-light ray: a hydrogen generation rate of 670 μmol h(-1) g(-1) (much higher than others reported previously in literature of N-doped TiO2 nanobelts).

  1. A high energy and power Li-ion capacitor based on a TiO2 nanobelt array anode and a graphene hydrogel cathode.

    PubMed

    Wang, Huanwen; Guan, Cao; Wang, Xuefeng; Fan, Hong Jin

    2015-03-25

    A novel hybrid Li-ion capacitor (LIC) with high energy and power densities is constructed by combining an electrochemical double layer capacitor type cathode (graphene hydrogels) with a Li-ion battery type anode (TiO(2) nanobelt arrays). The high power source is provided by the graphene hydrogel cathode, which has a 3D porous network structure and high electrical conductivity, and the counter anode is made of free-standing TiO(2) nanobelt arrays (NBA) grown directly on Ti foil without any ancillary materials. Such a subtle designed hybrid Li-ion capacitor allows rapid electron and ion transport in the non-aqueous electrolyte. Within a voltage range of 0.0-3.8 V, a high energy of 82 Wh kg(-1) is achieved at a power density of 570 W kg(-1). Even at an 8.4 s charge/discharge rate, an energy density as high as 21 Wh kg(-1) can be retained. These results demonstrate that the TiO(2) NBA//graphene hydrogel LIC exhibits higher energy density than supercapacitors and better power density than Li-ion batteries, which makes it a promising electrochemical power source.

  2. Fabrication of BiOBr nanosheets@TiO2 nanobelts p-n junction photocatalysts for enhanced visible-light activity

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Huang, Xiang; Tan, Xin; Yu, Tao; Li, Xiangli; Yang, Libin; Wang, Shucong

    2016-03-01

    The construction of p-n junction structure is a smart strategy for improving the photocatalytic activity, since p-n junctions can inhibit the recombination of photo-induced charges. Herein, BiOBr nanosheets@TiO2 nanobelts p-n junction photocatalysts were prepared by assembling BiOBr nanosheets on the surface of TiO2 nanobelts via a hydrothermal route followed by a co-precipitation process. BiOBr@TiO2 p-n junction photocatalysts exhibited enhanced photocatalytic activity in photocatalytic H2 production over water splitting and photodegradation of Rhodamine B (RhB) under visible light irradiation. Mott-Schottky plots confirmed the formation of p-n junctions in the interface of BiOBr and TiO2. The enhanced photocatalytic performance can be ascribed to the 1D nanostructure and the formation of p-n junctions. This work shows a potential application of low cost BiOBr as a substitute for noble metals in photocatalytic H2 production under visible light irradiation.

  3. MoS2 coating on MoO3 nanobelts: A novel approach for a high specific charge electrode for rechargeable Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Villevieille, Claire; Wang, Xiao-Jun; Krumeich, Frank; Nesper, Reinhard; Novák, Petr

    2015-04-01

    The electrochemical properties of MoS2 coated MoO3 nanobelts in lithium-ion batteries were investigated. A thin layer of MoS2 was coated on the nanobelts of MoO3 successfully through a facile sulfur transfer method, and the X-ray synchrotron diffraction revealed the crystallographic features of this composite material. The specific charge of the coated sample was beyond 1100 Ah/kg (at 1C rate) and 1400 Ah/kg at C/10 rate when tested in the 0.05 V-3.5 V vs. Li+/Li range. It was found that, with coating the Coulombic efficiency was higher than 98% which indicates a highly reversible process. Additionally, the electrochemical reaction and the degradation mechanism were studied by in situ X-ray synchrotron diffraction (1st and 50th cycle), and by post mortem SEM analysis. Both revealed a structural degradation as well as a surface degradation of the electrode by means of a thick amorphous layer on the surface of the active material.

  4. Graphene oxide coated coordination polymer nanobelt composite material: a new type of visible light active and highly efficient photocatalyst for Cr(VI) reduction.

    PubMed

    Shi, Gui-Mei; Zhang, Bin; Xu, Xin-Xin; Fu, Yan-Hong

    2015-06-28

    A visible light active photocatalyst was synthesized successfully by coating graphene oxide (GO) on a coordination polymer nanobelt (CPNB) using a simple colloidal blending process. Compared with neat CPNB, the resulting graphene oxide coated coordination polymer nanobelt composite material (GO/CPNB) exhibits excellent photocatalytic efficiency in the reduction of K2Cr2O7 under visible light irradiation. In the composite material, GO performs two functions. Firstly, it cuts down the band gap (E(g)) of the photocatalyst and extends its photoresponse region from the ultraviolet to visible light region. Secondly, GO exhibits excellent electron transportation ability that impedes its recombination with holes, and this can enhance photocatalytic efficiency. For GO, on its surface, the number of functional groups has a great influence on the photocatalytic performance of the resulting GO/CPNB composite material and an ideal GO"coater" to obtain a highly efficient GO/CPNB photocatalyst has been obtained. As a photocatalyst that may be used in the treatment of Cr(VI) in wastewater, GO/CPNB exhibited outstanding stability during the reduction of this pollutant.

  5. Modeling Total Suspended Solids (TSS) Concentrations in Narragansett Bay.

    EPA Science Inventory

    This work covers mechanistic modeling of suspended particulates in estuarine systems with an application to Narragansett Bay, RI. Suspended particles directly affect water clarity and attenuate light in the water column. Water clarity affects both phytoplankton and submerged aqua...

  6. Suspended monolayer graphene under true uniaxial deformation

    NASA Astrophysics Data System (ADS)

    Polyzos, Ioannis; Bianchi, Massimiliano; Rizzi, Laura; Koukaras, Emmanuel N.; Parthenios, John; Papagelis, Konstantinos; Sordan, Roman; Galiotis, Costas

    2015-07-01

    2D crystals, such as graphene, exhibit the higher strength and stiffness of any other known man-made or natural material. So far, this assertion has been primarily based on modelling predictions and on bending experiments in combination with pertinent modelling. True uniaxial loading of suspended graphene is not easy to accomplish; however such an experiment is of paramount importance in order to assess the intrinsic properties of graphene without the influence of an underlying substrate. In this work we report on uniaxial tension of graphene up to moderate strains of ~0.8%. This has been made possible by sandwiching the graphene flake between two polymethylmethacrylate (PMMA) layers and by suspending its central part by the removal of a section of PMMA with e-beam lithography. True uniaxial deformation is confirmed by the measured large phonon shifts with strain by Raman spectroscopy and the indication of lateral buckling (similar to what is observed for thin macroscopic membranes under tension). Finally, we also report on how the stress is transferred to the suspended specimen through the adhesive grips and determine the value of interfacial shear stress that is required for efficient axial loading in such a system.2D crystals, such as graphene, exhibit the higher strength and stiffness of any other known man-made or natural material. So far, this assertion has been primarily based on modelling predictions and on bending experiments in combination with pertinent modelling. True uniaxial loading of suspended graphene is not easy to accomplish; however such an experiment is of paramount importance in order to assess the intrinsic properties of graphene without the influence of an underlying substrate. In this work we report on uniaxial tension of graphene up to moderate strains of ~0.8%. This has been made possible by sandwiching the graphene flake between two polymethylmethacrylate (PMMA) layers and by suspending its central part by the removal of a section of

  7. Oscillation Control of Suspended Load with Flywheels

    NASA Astrophysics Data System (ADS)

    Tsuji, Toshiaki; Ohnishi, Kouhei

    This study is about an attitude control device applying flywheels. Reaction torque of a flywheel is applied for oscillation suppression of a suspended load. We suggest a sensorless estimation method of the attitude angular velocity. The band pass filter extracts the component of oscillation velocity from flywheel rotation velocity that contains various kinds of errors. A disturbance observer eliminates the steady state error on the wheel. Since the disturbance observer is for low frequency range, it does not interfere to angle velocity estimation. This attitude control device is convenient because it needs least calibrations when it is remounted on various suspended loads. The experimental result shows the validity of angle velocity estimation and the validity of oscillation suppression.

  8. Molybdenum-rhenium superconducting suspended nanostructures

    SciTech Connect

    Aziz, Mohsin; Christopher Hudson, David; Russo, Saverio

    2014-06-09

    Suspended superconducting nanostructures of MoRe 50%/50% by weight are fabricated employing commonly used fabrication steps in micro- and nano-meter scale devices followed by wet-etching with Hydro-fluoric acid of a SiO{sub 2} sacrificial layer. Suspended superconducting channels as narrow as 50 nm and length 3 μm have a critical temperature of ≈6.5 K, which can increase by 0.5 K upon annealing at 400 °C. A detailed study of the dependence of the superconducting critical current and critical temperature upon annealing and in devices with different channel widths reveals that desorption of contaminants is responsible for the improved superconducting properties. These findings pave the way for the development of superconducting electromechanical devices using standard fabrication techniques.

  9. Inclusions in freely suspended smectic films

    NASA Astrophysics Data System (ADS)

    Stannarius, Ralf; Harth, Kirsten

    Smectic liquid crystal phases have a unique property: Like soap solutions, they can form stable freely suspended films. Their aspect ratios can be larger than one million to one. Such films can serve as models for two-dimensional (2D) uids, with or without in-plane anisotropy. Solid or liquid inclusions trapped in these films by capillary forces can move in the film plane and interact with other inclusions, with film thickness gradients or the film boundaries, and even with the local orientation field. We describe preparation techniques to incorporate particles or droplets in thin smectic films, and optical observation methods. Several aspects make inclusions in freely suspended films interesting research objects: They provide rich information on capillary forces as well as surface and interfacial tensions, they can serve as platforms for hydrodynamic studies in 2D, and they may help to understand coalescence dynamics at the transition from 2D to 3D...

  10. Pointwise plucking of suspended carbon nanotubes.

    PubMed

    Luo, Jun; Ouyang, Wengen; Li, Xiaopei; Jin, Zhong; Yang, Leijing; Chen, Changqing; Zhang, Jin; Li, Yan; Warner, Jamie H; Peng, Lian-Mao; Zheng, Quanshui; Zhu, Jing

    2012-07-11

    Vibration of nanotubes/wires is significant for fundamental and applied researches. However, it remains challenging to control the vibration with point-level precision. Herein, individual suspended carbon nanotubes are plucked point by point to vibrate in scanning electron microscope with the electron beam as a nanoscale pointer. The vibration is directly imaged, and its images fit well with simulations from the plucking mechanism. This demonstrates a new way to manipulate the nanotube vibration with unprecedented precision.

  11. Characterization of suspended particles in Everglades wetlands

    USGS Publications Warehouse

    Noe, G.B.; Harvey, J.W.; Saiers, J.E.

    2007-01-01

    We report the concentration, phosphorus (P) and nitrogen (N) content, and size and chemical fractionation of fine suspended particles (0.2-100 ??m) and colloids (3 kilodalton [kDa]-0.1 ??m) in the surface water of Everglades wetlands along regional and P-enrichment gradients. Total suspended sediment concentrations ranged from 0.7 to 2.7 mg L-1. Total particulate P concentrations increased from 0.05 ??mol L-1 to 0.31 ??mol L -1 along the P-enrichment gradient. Particles contained from 20% to 43% of total P but <12% of total N in surface water. Dissolved (<0.2 ??m) organic N contained about 90% of total N, with the 3-100-kDa colloidal size class containing the most N of any size class. The 0.45-2.7-??m size fraction held the most particulate P at all sites, whereas particulate N was most abundant in the 2.7-10-??m size class at most sites. Standard chemical fractionation of particles identified acid-hydrolyzable P as the most abundant species of particulate P, with little reactive or refractory organic P. Sequential chemical extraction revealed that about 65% of total particulate P was microbial, while about 25% was associated with humic and fulvic organic matter. The size and chemical fractionation information suggested that P-rich particles mostly consisted of suspended bacteria. Suspended particles in Everglades wetlands were small in size and had low concentrations, yet they stored a large proportion of surface-water P in intermediately reactive forms, but they held little N. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

  12. Suspended sediments limit coral sperm availability

    PubMed Central

    Ricardo, Gerard F.; Jones, Ross J.; Clode, Peta L.; Humanes, Adriana; Negri, Andrew P.

    2015-01-01

    Suspended sediment from dredging activities and natural resuspension events represent a risk to the reproductive processes of coral, and therefore the ongoing maintenance of reefal populations. To investigate the underlying mechanisms that could reduce the fertilisation success in turbid water, we conducted several experiments exposing gametes of the corals Acropora tenuis and A. millepora to two sediment types. Sperm limitation was identified in the presence of siliciclastic sediment (230 and ~700 mg L−1), with 2–37 fold more sperm required to achieve maximum fertilisation rates, when compared with sediment-free treatments. This effect was more pronounced at sub-optimum sperm concentrations. Considerable (>45%) decreases in sperm concentration at the water’s surface was recorded in the presence of siliciclastic sediment and a >20% decrease for carbonate sediment. Electron microscopy then confirmed sediment entangled sperm and we propose entrapment and sinking is the primary mechanism reducing sperm available to the egg. Longer exposure to suspended sediments and gamete aging further decreased fertilisation success when compared with a shorter exposure. Collectively, these findings demonstrate that high concentrations of suspended sediments effectively remove sperm from the water’s surface during coral spawning events, reducing the window for fertilisation with potential subsequent flow-on effects for recruitment. PMID:26659008

  13. Acoustic vibrations of single suspended gold nanostructures

    NASA Astrophysics Data System (ADS)

    Major, Todd A.

    The acoustic vibrations for single gold nanowires and gold plates were studied using time-resolved ultrafast transient absorption. The objective of this work was to remove the contribution of the supporting substrate from the damping of the acoustic vibrations of the metal nano-objects. This was achieved by suspending the nano-objects across trenches created by photolithography and reactive ion etching. Transient absorption measurements for single suspended gold nanowires were initially completed in air and water environments. The acoustic vibrations for gold nanowires over the trench in air last typically for several nanoseconds, whereas gold nanowires in water are damped more quickly. Continuum mechanics models suggest that the acoustic impedance mismatch between air and water dominates the damping rate. Later transient absorption studies on single suspended gold nanowires were completed in glycerol and ethylene glycol environments. However, our continuum mechanical model suggests nearly complete damping in glycerol due to its high viscosity, but similar damping rates are seen between the two liquids. The continuum mechanics model thus incorrectly addresses high viscosity effects on the lifetimes of the acoustic vibrations, and more complicated viscoelastic interactions occur for the higher viscosity liquids. (Abstract shortened by UMI.).

  14. Suspended monolayer graphene under true uniaxial deformation.

    PubMed

    Polyzos, Ioannis; Bianchi, Massimiliano; Rizzi, Laura; Koukaras, Emmanuel N; Parthenios, John; Papagelis, Konstantinos; Sordan, Roman; Galiotis, Costas

    2015-08-14

    2D crystals, such as graphene, exhibit the higher strength and stiffness of any other known man-made or natural material. So far, this assertion has been primarily based on modelling predictions and on bending experiments in combination with pertinent modelling. True uniaxial loading of suspended graphene is not easy to accomplish; however such an experiment is of paramount importance in order to assess the intrinsic properties of graphene without the influence of an underlying substrate. In this work we report on uniaxial tension of graphene up to moderate strains of ∼0.8%. This has been made possible by sandwiching the graphene flake between two polymethylmethacrylate (PMMA) layers and by suspending its central part by the removal of a section of PMMA with e-beam lithography. True uniaxial deformation is confirmed by the measured large phonon shifts with strain by Raman spectroscopy and the indication of lateral buckling (similar to what is observed for thin macroscopic membranes under tension). Finally, we also report on how the stress is transferred to the suspended specimen through the adhesive grips and determine the value of interfacial shear stress that is required for efficient axial loading in such a system.

  15. Imaging Mechanical Vibrations in Suspended Graphene Sheets

    NASA Astrophysics Data System (ADS)

    Garcia-Sanchez, D.; van der Zande, A. M.; Paulo, A. San; Lassagne, B.; McEuen, P. L.; Bachtold, A.

    2008-05-01

    We carried out measurements on nanoelectromechanical systems based on multilayer graphene sheets suspended over trenches in silicon oxide. The motion of the suspended sheets was electrostatically driven at resonance using applied radio-frequency voltages. The mechanical vibrations were detected using a novel form of scanning probe microscopy, which allowed identification and spatial imaging of the shape of the mechanical eigenmodes. In as many as half the resonators measured, we observed a new class of exotic nanoscale vibration eigenmodes not predicted by the elastic beam theory, where the amplitude of vibration is maximum at the free edges. By modeling the suspended sheets with the finite element method, these edge eigenmodes are shown to be the result of non-uniform stress with remarkably large magnitudes (up to 1.5 GPa). This non-uniform stress, which arises from the way graphene is prepared by pressing or rubbing bulk graphite against another surface, should be taken into account in future studies on electronic and mechanical properties of graphene.

  16. Suspended sediments limit coral sperm availability.

    PubMed

    Ricardo, Gerard F; Jones, Ross J; Clode, Peta L; Humanes, Adriana; Negri, Andrew P

    2015-12-14

    Suspended sediment from dredging activities and natural resuspension events represent a risk to the reproductive processes of coral, and therefore the ongoing maintenance of reefal populations. To investigate the underlying mechanisms that could reduce the fertilisation success in turbid water, we conducted several experiments exposing gametes of the corals Acropora tenuis and A. millepora to two sediment types. Sperm limitation was identified in the presence of siliciclastic sediment (230 and ~700 mg L(-1)), with 2-37 fold more sperm required to achieve maximum fertilisation rates, when compared with sediment-free treatments. This effect was more pronounced at sub-optimum sperm concentrations. Considerable (>45%) decreases in sperm concentration at the water's surface was recorded in the presence of siliciclastic sediment and a >20% decrease for carbonate sediment. Electron microscopy then confirmed sediment entangled sperm and we propose entrapment and sinking is the primary mechanism reducing sperm available to the egg. Longer exposure to suspended sediments and gamete aging further decreased fertilisation success when compared with a shorter exposure. Collectively, these findings demonstrate that high concentrations of suspended sediments effectively remove sperm from the water's surface during coral spawning events, reducing the window for fertilisation with potential subsequent flow-on effects for recruitment.

  17. Transient dehydration of lungs in tail-suspended rats

    NASA Technical Reports Server (NTRS)

    Hargens, A. R.; Steskal, J.; Morey-Holton, E. R.

    1985-01-01

    The fluid balance in the lungs of rats exposed to head-down tilt is examined. Six Munich-Wister rats were suspended for 7 days and 10 Sprague-Dawley rats for 14 days using the technique of Morey (1979). The water contents of the lungs of the suspended and a control group are calculated and compared. The data reveal that the two-days suspended rats had dehydrated lungs; however, the lungs of the 14-day suspended and control group rats were similar. It is noted that the dehydration in the 2-day suspended rats is caused by general dehydration not the head-tilt position.

  18. Numerical Modeling and Experimental Validation by Calorimetric Detection of Energetic Materials Using Thermal Bimorph Microcantilever Array: A Case Study on Sensing Vapors of Volatile Organic Compounds (VOCs)

    PubMed Central

    Kang, Seok-Won; Fragala, Joe; Banerjee, Debjyoti

    2015-01-01

    Bi-layer (Au-Si3N4) microcantilevers fabricated in an array were used to detect vapors of energetic materials such as explosives under ambient conditions. The changes in the bending response of each thermal bimorph (i.e., microcantilever) with changes in actuation currents were experimentally monitored by measuring the angle of the reflected ray from a laser source used to illuminate the gold nanocoating on the surface of silicon nitride microcantilevers in the absence and presence of a designated combustible species. Experiments were performed to determine the signature response of this nano-calorimeter platform for each explosive material considered for this study. Numerical modeling was performed to predict the bending response of the microcantilevers for various explosive materials, species concentrations, and actuation currents. The experimental validation of the numerical predictions demonstrated that in the presence of different explosive or combustible materials, the microcantilevers exhibited unique trends in their bending responses with increasing values of the actuation current. PMID:26334276

  19. Real-time deflection and friction force imaging by bimorph-based resonance-type high-speed scanning force microscopy in the contact mode

    PubMed Central

    2014-01-01

    We report herein an alternative high-speed scanning force microscopy method in the contact mode based on a resonance-type piezoelectric bimorph scanner. The experimental setup, the modified optical beam deflection scheme suitable for smaller cantilevers, and a high-speed control program for simultaneous data capture are described in detail. The feature of the method is that the deflection and friction force images of the sample surface can be obtained simultaneously in real time. Images of various samples (e.g., a test grating, a thin gold film, and fluorine-doped tin oxide-coated glass slides) are acquired successfully. The imaging rate is 25 frames per second, and the average scan speed reaches a value of approximately 2.5 cm/s. The method combines the advantages of both observing the dynamic processes of the sample surface and monitoring the frictional properties on the nanometer scale. PACS 07.79.Lh; 07.79.Sp; 68.37.Ps PMID:25593555

  20. Monitoring of suspended sediment in South Tyrol

    NASA Astrophysics Data System (ADS)

    Nadalet, Rudi; Dinale, Roberto; Pernter, Martin; Maraldo, Luca; Peterlin, Dieter; Richter, Arnold; Comiti, Francesco

    2016-04-01

    In the context of the EU Water Framework Directive (WFD), which aims to achieve a good status of European water bodies, the Hydrographic Office of the Autonomous Province of Bolzano (Italy) extended in 2014 its institutional activities including the monitoring of suspended sediment in the river channel network. Currently, the only active monitoring station is on the Adige River at the gauging station of Ponte Adige near Bolzano (drainage area 2705 km2). The applied monitoring strategy and the data analysis concept are both based on the guidelines issued by the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (BMLFUW). The results indicates that the temporal variability strongly differs during the investigated period (2014-2015). In addition to the analysis of precipitation and water discharge, temperature and lightning activity were also included to better understand the sediment transport dynamics observed at the station. In summer 2015, the combination of constantly high daily temperature throughout the Adige basin (which drove intense glacier melting in the headwaters) with a high frequency of convective rainfall events (90% more than in 2014, obtained through lightning detection), led to an annual mass of transported suspended sediment of 260000 t. Interestingly, this value is similar to the one estimated for 2014 (300000 t), which was characterized by very different meteorological conditions (colder and wetter summer), but with the occurrence of an important flood in August, which transported half of the annual amount. Finally, we can conclude that the adopted monitoring strategy is applicable for institutional aims in terms of costs as well as in terms of time effort. During the next years, other stations for suspended sediment monitoring are planned to be installed in the Province to cover the most important river segments.

  1. DESORPTION OF PYRETHROIDS FROM SUSPENDED SOLIDS

    PubMed Central

    Fojut, Tessa L.; Young, Thomas M.

    2014-01-01

    Pyrethroid insecticides have been widely detected in sediments at concentrations that can cause toxicity to aquatic organisms. Desorption rates play an important role in determining the bioavailability of hydrophobic organic compounds, such as pyrethroids, because these compounds are more likely to be sorbed to solids in the environment and times to reach sorptive equilibrium can be long. In this study, sequential Tenax desorption experiments were performed with three sorbents, three aging times, and four pyrethroids. A biphasic rate model was fit to the desorption data with r2 > 0.99 and the rapid and slow compartment desorption rate constants and compartment fractions are reported. Suspended solids from irrigation runoff water collected from a field that had been sprayed with permethrin one day prior were used in the experiments to compare desorption rates for field-applied pyrethroids to those for laboratory-spiked materials. Suspended solids were used in desorption experiments because suspended solids can be a key source of hydrophobic compounds to surface waters. The rapid desorption rate parameters of field-applied permethrin were not statistically different than those of laboratory spiked permethrin, indicating that the desorption of the spiked pyrethroids is comparable to those added and aged in the field. Sorbent characteristics had the greatest effect on desorption rate parameters; as organic carbon content of the solids increased, the rapid desorption fractions and rapid desorption rate constants both decreased. The desorption rate constant of the slow compartment for sediment containing permethrin aged for 28 d was significantly different from those aged 1 d and 7 d, while desorption in the rapid and slow compartments did not differ between these treatments. PMID:21538493

  2. Intrinsic non-ohmic electronic transport properties of the transparent In-Zn-O compound nanobelts under ohmic contact and out of the space charge limited transport region

    NASA Astrophysics Data System (ADS)

    Wen, Jing; Zhang, Xitian; Gao, Hong

    2016-02-01

    It is generally accepted that the nonlinear I-V characteristics for semiconductor nanostructures are mainly induced by the Schottky contacts or by the space charge limited transport mechanism. We perform I-V measurements on undoped and doped In-Zn-O compound nanobelts and confirm that their intrinsic non-ohmic transport behaviors are not caused by these mechanisms. A model based on the hopping assisted trap state electrons transport process is introduced to explain the nonlinear I-V characteristics and to extract their electrical parameters. An understanding of this trap-state influenced carrier transport can advance the progress of nanomaterials applications and enable us to distinguish their intrinsic transport behaviors from contact effects. The results also indicate that the material has good electrical properties and can be used as a potential substitute for In2O3.

  3. Electronic thermal conductivity of suspended graphene

    SciTech Connect

    Begum, K. Rizwana Sankeshwar, N. S.

    2014-04-24

    Electronic thermal conductivity, κ{sub e}, of suspended graphene is studied for 20K 100K, becoming dominant for T > 250K. Good agreement with recent experimental data is obtained.

  4. Oscillation damped movement of suspended objects

    SciTech Connect

    Jones, J.F.; Petterson, B.J.

    1988-01-01

    Transportation of objects using overhead cranes or manipulators can induce pendulum motion of the object. Residual oscillation from transportation typically must be damped or allowed to decay before the next process can take place. By properly programming the acceleration of the transporting device (e.g., crane) an oscillation damped transport and swing free stop is obtainable. This paper reviews the theory associated with oscillation damped trajectories for simply suspended objects and describes a particular implementation using a CIMCORP XR 6100 gantry robot. 8 refs., 7 figs., 1 tab.

  5. Elastic properties of suspended black phosphorus nanosheets

    SciTech Connect

    Wang, Jia-Ying; Li, Yang; Zhen, Liang; Xu, Cheng-Yan; Zhan, Zhao-Yao; Li, Tie

    2016-01-04

    The mechanical properties of black phosphorus (BP) nanosheets suspended over circular holes were measured by an atomic force microscope nanoindentation method. The continuum mechanic model was introduced to calculate the elastic modulus and pretension of BP nanosheets with thicknesses ranging from 14.3 to 34 nm. Elastic modulus of BP nanosheets declines with thickness, and the maximum value is 276 ± 32.4 GPa. Besides, the effective strain of BP ranges from 8 to 17% with a breaking strength of 25 GPa. Our results show that BP nanosheets serve as a promising candidate for flexible electronic applications.

  6. Development of a magnetically suspended momentum wheel

    NASA Technical Reports Server (NTRS)

    Hamilton, S. B.

    1973-01-01

    An engineering model of a magnetically suspended momentum wheel was designed, fabricated, and tested under laboratory conditions. The basic unit consisted of two magnet bearings, a sculptured aluminum rotor, brushless dc spin motor, and electronics. The magnet bearings, utilizing rare-earth cobltrat-samarium magnets were active radially and passive axially. The results of the program showed that momentum wheels with magnetic bearings are feasible and operable, and that magnetic bearings of this type are capable of being used for applications where high capacity, high stiffness, and low power consumption are required. The tests performed developed criteria for improved performance for future designs.

  7. Safety Harness For Work Under Suspended Load

    NASA Technical Reports Server (NTRS)

    Sunoo, Su Young

    1994-01-01

    Safety device protects worker under suspended engine or other heavy load. Mechanically linked with load so if load should fall, worker yanked safely away. Worker wears chest-plate vest with straps crossing eye on back. Lower safety cable connected to eye extends horizontally away from worker to nearby wall, wrapped on pulley and extends upward to motion amplifier or reducer. Safety cables transform any sudden downward motion of overhanging load into rapid sideways motion of worker. Net catches worker, preventing worker from bumping against wall.

  8. Suspended-sediment inflows to Watts Bar Reservoir. Revision 1

    SciTech Connect

    Ewing, L.K.

    1993-09-01

    Suspended-sediment inflows to Watts Bar Reservoir are important data that are required in numerical modeling of transport and deposition of sediment in the reservoir. Acceptable numerical modeling requires sediment inflow rates and locations in order to be able to compute the location and quantity of sediment deposited within the reservoir. Therefore, the representativeness of modeling results is highly dependent on the characteristics of sediment input to the model. The following recommendations, that account for suspended-sediment inflows to be used in the numerical modeling of sediment transport and deposition in Watts Bar Reservoir, were developed through an evaluation of available watershed and sediment deposition data. (1) Use the suspended-sediment rating regression equations of Gaydos et al., for Emory River at Oakdale, TN, and for Poplar Creek near Oak Ridge, TN, to represent the suspended-sediment inflows into Watts Bar Reservoir from its tributaries; (2) Use a suspended-sediment rating regression equation that was derived from suspended-sediment and streamflow data of the Little Tennessee River at McGhee, TN, to represent sediment inflow from the Little Tennessee River for simulation of any historical year before the completion of Tellico Dam; (3) Check the appropriateness of any assumption for suspended-sediment inflows from upstream reservoirs by using its long-term relationship to local suspended-sediment inflows and to the suspended-sediment outflow through Watts Bar Dam; and (4) Focus refinements to suspended-sediment inflow rates on the Clinch arm of Watts Bar Reservoir.

  9. Black TiO2 nanobelts/g-C3N4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance.

    PubMed

    Shen, Liyan; Xing, Zipeng; Zou, Jinlong; Li, Zhenzi; Wu, Xiaoyan; Zhang, Yuchi; Zhu, Qi; Yang, Shilin; Zhou, Wei

    2017-02-06

    Black TiO2 nanobelts/g-C3N4 nanosheets laminated heterojunctions (b-TiO2/g-C3N4) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption, and UV-visible diffuse reflectance spectroscopy, respectively. The results show that special laminated heterojunctions are formed between black TiO2 nanobelts and g-C3N4 nanosheets, which favor the separation of photogenerated electron-hole pairs. Furthermore, the presence of Ti(3+) and g-C3N4 greatly enhance the absorption of visible light. The resultant b-TiO2/g-C3N4 materials exhibit higher photocatalytic activity than that of g-C3N4, TiO2, b-TiO2 and TiO2/g-C3N4 for degradation of methyl orange (95%) and hydrogen evolution (555.8 μmol h(-1 )g(-1)) under visible light irradiation. The apparent reaction rate constant (k) of b-TiO2/g-C3N4 is ~9 times higher than that of pristine TiO2. Therefore, the high-efficient laminated heterojunction composites will have potential applications in fields of environment and energy.

  10. Black TiO2 nanobelts/g-C3N4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance

    PubMed Central

    Shen, Liyan; Xing, Zipeng; Zou, Jinlong; Li, Zhenzi; Wu, Xiaoyan; Zhang, Yuchi; Zhu, Qi; Yang, Shilin; Zhou, Wei

    2017-01-01

    Black TiO2 nanobelts/g-C3N4 nanosheets laminated heterojunctions (b-TiO2/g-C3N4) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption, and UV-visible diffuse reflectance spectroscopy, respectively. The results show that special laminated heterojunctions are formed between black TiO2 nanobelts and g-C3N4 nanosheets, which favor the separation of photogenerated electron-hole pairs. Furthermore, the presence of Ti3+ and g-C3N4 greatly enhance the absorption of visible light. The resultant b-TiO2/g-C3N4 materials exhibit higher photocatalytic activity than that of g-C3N4, TiO2, b-TiO2 and TiO2/g-C3N4 for degradation of methyl orange (95%) and hydrogen evolution (555.8 μmol h−1 g−1) under visible light irradiation. The apparent reaction rate constant (k) of b-TiO2/g-C3N4 is ~9 times higher than that of pristine TiO2. Therefore, the high-efficient laminated heterojunction composites will have potential applications in fields of environment and energy. PMID:28165021

  11. Black TiO2 nanobelts/g-C3N4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance

    NASA Astrophysics Data System (ADS)

    Shen, Liyan; Xing, Zipeng; Zou, Jinlong; Li, Zhenzi; Wu, Xiaoyan; Zhang, Yuchi; Zhu, Qi; Yang, Shilin; Zhou, Wei

    2017-02-01

    Black TiO2 nanobelts/g-C3N4 nanosheets laminated heterojunctions (b-TiO2/g-C3N4) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption, and UV-visible diffuse reflectance spectroscopy, respectively. The results show that special laminated heterojunctions are formed between black TiO2 nanobelts and g-C3N4 nanosheets, which favor the separation of photogenerated electron-hole pairs. Furthermore, the presence of Ti3+ and g-C3N4 greatly enhance the absorption of visible light. The resultant b-TiO2/g-C3N4 materials exhibit higher photocatalytic activity than that of g-C3N4, TiO2, b-TiO2 and TiO2/g-C3N4 for degradation of methyl orange (95%) and hydrogen evolution (555.8 μmol h‑1 g‑1) under visible light irradiation. The apparent reaction rate constant (k) of b-TiO2/g-C3N4 is ~9 times higher than that of pristine TiO2. Therefore, the high-efficient laminated heterojunction composites will have potential applications in fields of environment and energy.

  12. A comparison of load estimates using total suspended solids and suspended-sediment concentration data

    USGS Publications Warehouse

    Glysson, G.D.; Gray, J.R.; Schwarz, G.E.

    2001-01-01

    This paper presents the results to-date from a continuing investigation into the differences between total suspended solids (TSS) and suspended-sediment concentration (SSC) data and the ramifications of using each type of data to estimate sediment loads. It compares estimates of annual suspended-sediment loads that were made using regression equations developed from paired TSS and SSC data, to annual loads computed by the U.S. Geological Survey (USGS) using traditional techniques and SSC data. Load estimates were compared for 10 stations where sufficient TSS and SSC paired data were available to develop sediment-transport curves for the same time period that daily suspended-sediment records were available. Results of these analyses indicate that as the time frame over which the estimates were made increases, the overall errors associated with the estimates decreases with respect to loads computed using traditional USGS techniques. Using SSC data to compute loads tends to produce estimates closer to those computed by traditional techniques than those computed from TSS data. Loads computed from TSS data tend to be negatively biased with respect to those computed by traditional USGS techniques.

  13. Nanoscale coating of LiMO2 (M = Ni, Co, Mn) nanobelts with Li+-conductive Li2TiO3: toward better rate capabilities for Li-ion batteries.

    PubMed

    Lu, Jun; Peng, Qing; Wang, Weiyang; Nan, Caiyun; Li, Lihong; Li, Yadong

    2013-02-06

    By using a novel coating approach based on the reaction between MC(2)O(4)·xH(2)O and Ti(OC(4)H(9))(4), a series of nanoscale Li(2)TiO(3)-coated LiMO(2) nanobelts with varied Ni, Co, and Mn contents was prepared for the first time. The complete, thin Li(2)TiO(3) coating layer strongly adheres to the host material and has a 3D diffusion path for Li(+) ions. It is doped with Ni(2+) and Co(3+) ions in addition to Ti(4+) in LiMO(2), both of which were found to favor Li(+)-ion transfer at the interface. As a result, the coated nanobelts show improved rate, cycling, and thermal capabilities when used as the cathode for Li-ion battery.

  14. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2002-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  15. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2001-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  16. Acoustic measuring techniques for suspended sediment

    NASA Astrophysics Data System (ADS)

    Gruber, P.; Felix, D.; Storti, G.; Lattuada, M.; Fleckenstein, P.; Deschwanden, F.

    2016-11-01

    Acoustic signals can be used in various ways for suspended sediment monitoring. One possibility which lends itself particularly well in the context of hydropower plants (HPPs), is to use installations for acoustic discharge measurement (ADM). Such installations already exist at waterways of many HPPs. Similar to certain turbidimeters, the attenuation of the forward scattered signal travelling through the water-sediment mixture is correlated with suspended sediment concentration (SSC). This correlation can be based on reference SSCs, e.g. from gravimetric analyses of bottle samples. Without the need of additional sensors and practically maintenance-free, this method is used successfully in the HPP Fieschertal to warn the HPP operator of high SSC to prevent excessive turbine abrasion. Acoustic methods and systems that allow for estimating both SSC and particle size distribution (PSD) are under development. The simultaneous determination of SSC and PSD is not possible using a single frequency. Therefore, multi-frequency approaches are investigated for generally scattered signals. When backscattered signals are used, a stronger frequency dependency can be exploited. However, the reliable simultaneous determination of particle size (and distribution) and concentration is still a major challenge due to a low signal-to-noise ratio and an ill- posed problem of estimating concentration and size from recorded signals. The optimal setup configuration (angles, frequencies) for such a system is not unique and further investigations are recommended.

  17. Electrodialytic remediation of suspended mine tailings.

    PubMed

    Hansen, Henrik K; Rojo, Adrian; Pino, Denisse; Ottosen, Lisbeth M; Ribeiro, Alexandra B

    2008-07-01

    This work shows the laboratory results of nine electrodialytic remediation experiments on copper mine tailings. A newly designed remediation cell, where the solids were kept in suspension by airflow, was tested. The results show that electric current could remove copper from suspended tailings applying 40 mA during 7 days. The liquid-to-solid ratios used were 3, 6 and 9 mL g(- 1). With addition of sulfuric acid, the process was enhanced because the pH decreased to either 2 or 4, and copper was therefore dissolved. The maximum copper removal was 80% with addition of sulfuric acid in 7-day experiment at 40 mA, with approximately 137.5 g mine tailings on dry basis. The removal for a static (baseline) experiment only amounted 15% when passing approximately the same amount of charge through 130 g of mine tailings. The use of air bubbling to keep the tailings suspended increased the removal efficiency from 1% to 80% compared to experiments with no stirring but with the same operational conditions. This showed the crucial importance of having the solids in suspension and not settled during the remediation.

  18. Method for forming suspended micromechanical structures

    DOEpatents

    Fleming, James G.

    2000-01-01

    A micromachining method is disclosed for forming a suspended micromechanical structure from {111} crystalline silicon. The micromachining method is based on the use of anisotropic dry etching to define lateral features of the structure which are etched down into a {111}-silicon substrate to a first etch depth, thereby forming sidewalls of the structure. The sidewalls are then coated with a protection layer, and the substrate is dry etched to a second etch depth to define a spacing of the structure from the substrate. A selective anisotropic wet etchant (e.g. KOH, EDP, TMAH, NaOH or CsOH) is used to laterally undercut the structure between the first and second etch depths, thereby forming a substantially planar lower surface of the structure along a {111} crystal plane that is parallel to an upper surface of the structure. The lateral extent of undercutting by the wet etchant is controlled and effectively terminated by either timing the etching, by the location of angled {111}-silicon planes or by the locations of preformed etch-stops. This present method allows the formation of suspended micromechanical structures having large vertical dimensions and large masses while allowing for detailed lateral features which can be provided by dry etch definition. Additionally, the method of the present invention is compatible with the formation of electronic circuitry on the substrate.

  19. Elastic properties of suspended multilayer WSe2

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Koutsos, Vasileios; Cheung, Rebecca

    2016-01-01

    We report the experimental determination of the elastic properties of suspended multilayer WSe2, a promising two-dimensional (2D) semiconducting material combined with high optical quality. The suspended WSe2 membranes have been fabricated by mechanical exfoliation of bulk WSe2 and transfer of the exfoliated multilayer WSe2 flakes onto SiO2/Si substrates pre-patterned with hole arrays. Then, indentation experiments have been performed on these membranes with an atomic force microscope. The results show that the 2D elastic modulus of the multilayer WSe2 membranes increases linearly while the prestress decreases linearly as the number of layers increases. The interlayer interaction in WSe2 has been observed to be strong enough to prevent the interlayer sliding during the indentation experiments. The Young's modulus of multilayer WSe2 (167.3 ± 6.7 GPa) is statistically independent of the thickness of the membranes, whose value is about two thirds of other most investigated 2D semiconducting transition metal dichalcogenides, namely, MoS2 and WS2. Moreover, the multilayer WSe2 can endure ˜12.4 GPa stress and ˜7.3% strain without fracture or mechanical degradation. The 2D WSe2 can be an attractive semiconducting material for application in flexible optoelectronic devices and nano-electromechanical systems.

  20. Probing microstructure and phase evolution of α-MoO3 nanobelts for sodium-ion batteries by in situ transmission electron microscopy

    SciTech Connect

    Xia, Weiwei; Xu, Feng; Zhu, Chongyang; Xin, Huolin L.; Xu, Qingyu; Sun, Pingping; Sun, Litao

    2016-07-15

    The fundamental electrochemical reaction mechanisms and the phase transformation pathways of layer-structured α-MoO3 nanobelt during the sodiation/desodiation process to date remain largely unknown. In this study, to observe the real-time sodiation/desodiaton behaviors of α-MoO3 during electrochemical cycling, we construct a MoO3 anode sodium-ion battery inside a transmission electron microscope (TEM). Utilizing in situ TEM and electron diffraction pattern (EDP) observation, α-MoO3 nanobelts are found to undergo a unique multi-step phase transformation. Upon the first sodiation, α-MoO3 nanobelts initially form amorphous NaxMoO3 phase and are subsequently sodiated into intermediate phase of crystalline NaMoO2, finally resulting in the crystallized Mo nanograins embedded within the Na2O matrix. During the first desodiation process, Mo nanograins are firstly re-oxidized into intermediate phase NaMoO2 that is further transformed into amorphous Na2MoO3, resulting in an irreversible phase transformation. Upon subsequent sodiation/desodiation cycles, however, a stable and reversible phase transformation between crystalline Mo and amorphous Na2MoO3 phases has been revealed. In conclusion, our work provides an in-deepth understanding of the phase transformation pathways of α-MoO3 nanobelts upon electrochemical sodiation/desodiation processes, with the hope of assistance in designing sodium-ion batteries with enhanced performance.

  1. Reconviction rates after suspended sentences: comparison of the effects of different types of suspended sentences on reconviction in the Netherlands.

    PubMed

    Aarten, Pauline G M; Denkers, Adriaan; Borgers, Matthias J; van der Laan, Peter H

    2015-02-01

    Previous research has focused mainly on determining the effectiveness of suspended sentences compared with other sentences, and seldom on understanding to what extent the different types of suspended sentences reduce recidivism rates. This study examined reconviction rates of offenders (N = 1,258) who received fully or partly suspended prison sentences, with or without special conditions, in 2006 in two of the largest court districts in the Netherlands. Cox proportional hazard models revealed no difference in reconviction rates between fully and partly suspended prison sentences, with and without special conditions. However, suspended sentences without special conditions had significantly lower reconviction rates compared with special conditions that were solely control-orientated. Although there are indications that certain types of suspended sentences reduced reconviction rates more than other types, more rigorous research is still required.

  2. Suspended sediment yield in Texas watersheds

    NASA Astrophysics Data System (ADS)

    Coonrod, Julia Ellen Allred

    The Texas Water Development Board collected suspended sediment samples across the state of Texas for approximately 60 years. Until this research, no comprehensive analysis of the data had been conducted. This study compiles the suspended sediment data along with corresponding streamflow and rainfall. GIS programs are developed which characterize watersheds corresponding to the sediment gauging stations. The watersheds are characterized according to topography, climate, soils, and land use. All of the data is combined to form several SAS data sets which can subsequently be analyzed using regression. Annual data for all of the stations across the state are classified temporally and spatially to determine trends in the sediment yield. In general, the suspended sediment load increases with increasing runoff but no correlation exists with rainfall. However, the annual average rainfall can be used to classify the watersheds according to climate, which improves the correlation between sediment load and runoff. The watersheds with no dams have higher sediment loads than watersheds with dams. Dams in the drier parts of Texas reduce the sediment load more than dams in the wetter part of the state. Sediment rating curves are developed separately for each basin in Texas. All but one of the curves fall into a band which varies by about two orders of magnitude. The study analyzes daily time series data for the Lavaca River near Edna station. USGS data are used to improve the sediment rating curve by the addition of physically related variables and interaction terms. The model can explain an additional 41% of the variability in sediment concentration compared to a simple bivariate regression of sediment load and flow. The TWDB daily data for the Lavaca River near Edna station are used to quantify temporal trends. There is a high correlation between sediment load and flowrate for the Lavaca River. The correlation can be improved by considering a flow-squared term and by

  3. An equivalent network representation of a clamped bimorph piezoelectric micromachined ultrasonic transducer with circular and annular electrodes using matrix manipulation techniques.

    PubMed

    Sammoura, Firas; Smyth, Katherine; Kim, Sang-Gook

    2013-09-01

    An electric circuit model for a clamped circular bimorph piezoelectric micromachined ultrasonic transducer (pMUT) was developed for the first time. The pMUT consisted of two piezoelectric layers sandwiched between three thin electrodes. The top and bottom electrodes were separated into central and annular electrodes by a small gap. While the middle electrode was grounded, the central and annular electrodes were biased with two independent voltage sources. The strain mismatch between the piezoelectric layers caused the plate to vibrate and transmit a pressure wave, whereas the received echo generated electric charges resulting from plate deformation. The clamped pMUT plate was separated into a circular and an annular plate, and the respective electromechanical transformation matrices were derived. The force and velocity vectors were properly selected using Hamilton's principle and the necessary boundary conditions were invoked. The electromechanical transformation matrix for the clamped circular pMUT was deduced using simple matrix manipulation techniques. The pMUT performance under three biasing schemes was elaborated: 1) central electrode only, 2) central and annular electrodes with voltages of the same magnitude and polarity, and 3) central and annular electrodes with voltages of the same magnitude and opposite polarity. The circuit parameters of the pMUT were extracted for each biasing scheme, including the transformer ratio, the clamped electric impedance, and the open-circuit mechanical impedance. Each pMUT scheme was characterized under different acoustic loadings using the theoretically developed model, which was verified with finite element modeling (FEM) simulation. The electrode size was optimized to maximize the electromechanical transformer ratio. As such, the developed model could provide more insight into the design, optimization, and characterization of pMUTs and allow for performance comparison with their cMUT counterparts.

  4. System characterization of a magnetically suspended flywheel

    NASA Technical Reports Server (NTRS)

    Kirk, James A.; Anand, Dave K.; Plant, David P.

    1988-01-01

    The purpose of flywheel energy storage is to provide a means to save energy during times when the satellite is in sunlight, and then return the energy during the time when the satellite is in darkness. Typically, an energy storage device operates cyclically, where for satellites in Low Earth Orbit (LEO) the typical period is 60 minutes of sunlight followed by 30 minutes of darkness. If a lifetime of 17 years is required the energy storage system must be capable of sustaining approximately 100,000 cycles. The recent developments at the University of Maryland and how these progressions apply to a 500 Watt-hour magnetically suspended flywheel stack energy storage system are covered. The work includes hardware testing results from a stack flywheel energy storage system, improvements in the area of non-contacting displacement transducers, and performance enhancements of magnetic bearings. The experimental results show that a stack flywheel energy storage system is a feasible technology.

  5. Flywheel energy storage. II - Magnetically suspended superflywheel

    NASA Technical Reports Server (NTRS)

    Kirk, J. A.; Studer, P. A.

    1977-01-01

    This article, the second of a two part paper, describes the general design requirements for a flywheel energy storage system. A new superflywheel energy storage system, using a spokeless, magnetically suspended, composite material pierced disk rotor is proposed. The new system is configured around a permanent magnet ('flux biased') magnetic suspension system with active control in the radial direction and passive control in the axial direction. The storage ring is used as a moving rotor and electronic commutation of stationary armature coils is proposed. There is no mechanical contact with the rotating ring and long life and low run down losses are projected. A discussion of major components for a 10 kwh system is presented.

  6. Electrically rotating suspended films of polar liquids

    NASA Astrophysics Data System (ADS)

    Shirsavar, R.; Amjadi, A.; Tonddast-Navaei, A.; Ejtehadi, M. R.

    2011-02-01

    Controlled rotation of a suspended soap water film, simply generated by applying an electric field, has been reported recently. The film rotates when the applied electric field exceeds a certain threshold. In this study, we investigate the phenomenon in films made of a number of other liquids with various physical and chemical properties. Our measurements show that the intrinsic electrical dipole moments of the liquid molecules seems to be vital for the corresponding film rotation. All the investigated rotating liquids have a molecular electric dipole moment of above 1 Debye, while weakly polar liquids do not rotate. However, the liquids investigated here cover a wide range of physical parameters (e.g. viscosity, density, conductivity, etc.). So far, no significant correlation has been observed between the electric field thresholds and macroscopic properties of the liquids.

  7. Actively suspended counter-rotating machine

    NASA Technical Reports Server (NTRS)

    Studer, Philip A. (Inventor)

    1983-01-01

    A counter-rotating machine, such as a positive displacement pump having a pair of meshed, non-contacting helical screws (10,12), subjects its rotating members to axial and radial thrust forces when used for such purposes as compression of liquid or gaseous phase fluids while transporting them through a pump cavity (11,13). Each helical screw (10,12) has a shaft (17,17') which is actively suspended at opposite ends (11a,11b) of the pump cavity by a servo-controlled magnetic bearing assembly (19) and a servo-controlled rotary drive motor (20). Both bearing assemblies and drive motors are mounted on the outside of the pump cavity (11,13). Opto-electric angular position sensors (250) provide synchronization between radial orientation of the drive motors. The bearing assemblies and drive motors conjugately provide axial stabilization and radial centering of the helical screws during volumetric compression of aspirated liquid or gaseous phase fluids.

  8. Design consideration for magnetically suspended flywheel systems

    NASA Technical Reports Server (NTRS)

    Anand, D.; Kirk, J. A.; Frommer, D. A.

    1985-01-01

    Consideration is given to the design, fabrication, and testing of a magnetically suspended flywheel system for energy storage applications in space. The device is the prototype of a system combining passive suspension of the flywheel plate by samarium cobalt magnets and active control in the radial direction using eight separate magnetic coils. The bearing assembly was machined from a nickel-iron alloy, and the machine parts are all hydrogen annealed. Slots in the magnetic plate allow four independent quadrants for control. The motor/generator component of the system is a brushless dc-permanent magnetic/ironless engine using electronic communication. The system has been tested at over 2500 rpm with satisfactory results. The system characteristics of the flywheel for application in low earth orbit (LEO) are given in a table.

  9. Parachute suspended solar pointing control system

    NASA Astrophysics Data System (ADS)

    Sakoda, G. T.; Fujimoto, R. J.; Shigemoto, J. M.; Windsor, R. M.

    A high altitude parachute suspended solar pointing control system has been developed and flight tested for use in the altitude range of 30 to 70 kilometers. This development provides an opportunity for extended solar observations at altitudes higher than that attainable by helium balloons. The new system utilizes the NASA high altitude cross parachute to slow the descent of a rocket launched payload allowing observations in the region of interest. Solar pointing is established by using solar sensors in conjunction with a servo controlled platform and cold gas thrusters for payload roll control. The inherent spin of the cross parachute is decoupled by a swivel joint attached to the parachute suspension lines. This paper describes the design, test and flight performance of the new system.

  10. Parachute-suspended solar pointing control system

    NASA Astrophysics Data System (ADS)

    Sakoda, G. T.; Fujimoto, R. J.; Shigemoto, J. M.; Windsor, R. M.

    1984-04-01

    A high altitude parachute suspended solar pointing control system has been developed and flight tested for use in the altitude range of 30 to 70 kilometers. This development provides an opportunity for extended solar observations at altitudes higher than that attainable by helium balloons. The new system utilizes the NASA high altitude cross parachute to slow the descent of a rocket launched payload allowing observations in the region of interest. Solar pointing is established by using solar sensors in conjunction with a servo controlled platform and cold gas thrusters for payload roll control. The inherent spin of the cross parachute is decoupled by a swivel joint attached to the parachute suspension lines. This paper describes the design, test and flight performance of the new system.

  11. Properties of freely suspended liquid crystal films and their applications

    NASA Astrophysics Data System (ADS)

    Yablonskii, S. V.; Bodnarchuk, V. V.; Yoshino, K.

    2016-05-01

    We report the review on the physical properties of the liquid crystal freely suspended films. The importance of the freely suspended films for the study of the fundamental problems of the self-confined systems as well as their practical implementations are demonstrated.

  12. Suspended sediment in Trail Creek at Michigan City, Indiana

    USGS Publications Warehouse

    Crawford, Charles G.; Jacques, David V.

    1992-01-01

    Trail Creek is a small (54.1-square-mile drainage area) tributary of Lake Michigan located in northwestern Indiana. A harbor at the mouth of the stream has experienced excessive sediment deposition. A study was done to investigate the suspended-sediment characteristics of Trail Creek. The study included analysis of suspended-sediment concentration and particle-size data, and estimates of annual suspended-sediment load. Suspended-sediment concentrations ranged from only a few milligrams per liter at low flows to about 300 milligrams per liter at high flows. At low flows, the suspended sediment was mostly silt- and clay-sized material (less than 0.062 millimeter). The percentage of silt- and clay-sized material gradually decreased to about 50 percent of the suspended sediment at high flows. Estimates of the annual suspended-sediment load for the 1981-90 water years were calculated by the flow-duration, rating-curve method. Annual loads ranged from 3,690 to 8,250 tons. The average annual load for the 10-year period was 6,180 tons. Annual suspended-sediment yield (load per unit drainage area) averaged 114 tons per square mile; this value is within the range of values from 14 other previously investigated streams in northern Indiana. Average annual yields of these 14 streams ranged from 11 to 152 tons per square mile; the median annual yield was 56 tons per square mile.

  13. 40 CFR 52.330 - Control strategy: Total suspended particulates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Control strategy: Total suspended... PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Colorado § 52.330 Control strategy: Total suspended particulates. (a) Part D—Conditional Approval: The Pueblo plan is approved assuming...

  14. 40 CFR 230.21 - Suspended particulates/turbidity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., usually smaller than silt, and organic particles. Suspended particulates may enter water bodies as a..., and man's activities including dredging and filling. Particulates may remain suspended in the water column for variable periods of time as a result of such factors as agitation of the water...

  15. Suspended particulate matter in the Chesapeake Bay entrance and adjacent shelf waters

    NASA Technical Reports Server (NTRS)

    Gingerich, K. J.; Oertel, G. F.

    1981-01-01

    Approximately 400 samples were collected from the mouth of the Chesapeake Bay for various analyses, including 138 for suspended solids. Characteristics of suspended solids that were analyzed included: total suspended matter; total suspended inorganics, total suspended organics; percent organics; particle size distribution; and presence or absence of 11 of the most prominent particle types.

  16. Sensorless Oscillation Control of a Suspended Load with Flywheels

    NASA Astrophysics Data System (ADS)

    Nishimura, Koichi; Tsuji, Toshiaki; Ohnishi, Kouhei

    This study proposes a method of sensorless oscillation control of a suspended load. To suppress oscillation of a suspended load, we use flywheels as a control device. Reaction torque of flywheels is applied for the oscillation control. An angular velocity value of a suspended load must be acquired for the oscillation control. Therefore, a method to estimate the angular velocity value is indispensable. By conventional methods, the estimation and the oscillation control cannot be realized simultaneously in case of one flywheel. Hence, inertia torque observer is proposed. Inertia torque appears as a disturbance torque on flywheels when a suspended load is oscillating. The angular velocity value is calculated based on this inertia toque. By using inertia torque observer, estimation of the angular velocity value and oscillation control of a suspended load are achieved at the same time.

  17. 21 CFR 1404.715 - What notice does the suspending official give me if I am suspended?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false What notice does the suspending official give me if I am suspended? 1404.715 Section 1404.715 Food and Drugs OFFICE OF NATIONAL DRUG CONTROL POLICY... this part, and any other Office of National Drug Control Policy procedures governing...

  18. 21 CFR 1404.715 - What notice does the suspending official give me if I am suspended?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false What notice does the suspending official give me if I am suspended? 1404.715 Section 1404.715 Food and Drugs OFFICE OF NATIONAL DRUG CONTROL POLICY... this part, and any other Office of National Drug Control Policy procedures governing...

  19. 21 CFR 1404.715 - What notice does the suspending official give me if I am suspended?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false What notice does the suspending official give me if I am suspended? 1404.715 Section 1404.715 Food and Drugs OFFICE OF NATIONAL DRUG CONTROL POLICY... this part, and any other Office of National Drug Control Policy procedures governing...

  20. 21 CFR 1404.715 - What notice does the suspending official give me if I am suspended?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false What notice does the suspending official give me if I am suspended? 1404.715 Section 1404.715 Food and Drugs OFFICE OF NATIONAL DRUG CONTROL POLICY... this part, and any other Office of National Drug Control Policy procedures governing...

  1. Droplet Suspended on a Wire Begins Ignition

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber Supported Droplet Combustion Experiment completing a number of successful burns on STS-94, July 11, 1997, MET:9/17:40 (approximate). The photo shows a droplet of 95% heptane and 5% hexadecane, suspended and positioned by the fiber wire, just as it is being ignited by the glowing coil beneath. Study of the physical properties of burning fuel from this experiment is expected to contribute to more efficient use of fossil fuels and reduction of combustion by-products on Earth. The sequence is from a time-lapse movie (34 seconds condensed to 12 seconds), and clearly shows particles emanating from the droplet during the burn. The droplet shrank to nothing as it was consumed. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.2 MB, 11-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300180.html.

  2. Ignition of Droplet Suspended on a Wire

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber Supported Droplet Combustion Experiment completing a number of successful burns on STS-94, July 11, 1997, MET:9/17:40 (approximate). The photo shows a droplet of 95% heptane and 5% hexadecane, suspended and positioned by the fiber wire, just as it is being ignited by the glowing coil beneath. Study of the physical properties of burning fuel from this experiment is expected to contribute to more efficient use of fossil fuels and reduction of combustion by-products on Earth. The sequence is from a time-lapse movie (34 seconds condensed to 12 seconds), and clearly shows particles emanating from the droplet during the burn. The droplet shrank to nothing as it was consumed. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (133KB JPEG, 656 x 741 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300181.html.

  3. Cokriging estimation of daily suspended sediment loads

    USGS Publications Warehouse

    Li, Z.; Zhang, Y.-K.; Schilling, K.; Skopec, M.

    2006-01-01

    Daily suspended sediment loads (S) were estimated using cokriging (CK) of S with daily river discharge based on weekly, biweekly, or monthly sampled sediment data. They were also estimated with ordinary kriging (OK) and a rating curve method. The estimated daily loads were compared with the daily measured values over a nine-year-period. The results show that the estimated daily sediment loads with the CK using the weekly measured data best matched the measured daily values. The rating curve method based on the same data provides a fairly good match but it tends to underestimate the peak and overestimate the low values. The CK estimation was better than the rating curve because CK considers the temporal correlation among the data values and honors the measured points whereas the rating curve method does not. For the site studied, weekly sampling may be frequent enough for estimating daily sediment loads with CK when daily discharge data is available. The estimated daily loads with CK were less reliable when the sediment samples were taken less frequently, i.e., biweekly or monthly. The OK estimates using the weekly measured data significantly underestimates the daily S because unlike CK and the rating curve, OK makes no use of the correlation of sediment loads with frequently measured river discharge. ?? 2005 Elsevier B.V. All rights reserved.

  4. Triad mode resonant interactions in suspended cables

    NASA Astrophysics Data System (ADS)

    Guo, TieDing; Kang, HouJun; Wang, LianHua; Zhao, YueYu

    2016-03-01

    A triad mode resonance, or three-wave resonance, is typical of dynamical systems with quadratic nonlinearities. Suspended cables are found to be rich in triad mode resonant dynamics. In this paper, modulation equations for cable's triad resonance are formulated by the multiple scale method. Dynamic conservative quantities, i.e., mode energy and Manley-Rowe relations, are then constructed. Equilibrium/dynamic solutions of the modulation equations are obtained, and full investigations into their stability and bifurcation characteristics are presented. Various bifurcation behaviors are detected in cable's triad resonant responses, such as saddle-node, Hopf, pitchfork and period-doubling bifurcations. Nonlinear behaviors, like jump and saturation phenomena, are also found in cable's responses. Based upon the bifurcation analysis, two interesting properties associated with activation of cable's triad resonance are also proposed, i.e., energy barrier and directional dependence. The first gives the critical amplitude of high-frequency mode to activate cable's triad resonance, and the second characterizes the degree of difficulty for activating cable's triad resonance in two opposite directions, i.e., with positive or negative internal detuning parameter.

  5. Methods of and system for swing damping movement of suspended objects

    DOEpatents

    Jones, J.F.; Petterson, B.J.; Strip, D.R.

    1991-03-05

    A payload suspended from a gantry is swing damped in accordance with a control algorithm based on the periodic motion of the suspended mass or by servoing on the forces induced by the suspended mass. 13 figures.

  6. 76 FR 54735 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-02

    ... International Trade Administration Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation... countervailing duty order, finding, or suspended investigation. All deadlines for the submission of comments or... request administrative review of the following orders, findings, or suspended investigations,...

  7. 77 FR 44233 - Clothianidin; Emergency Petition To Suspend; Notice of Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ... AGENCY Clothianidin; Emergency Petition To Suspend; Notice of Availability AGENCY: Environmental... immediately suspend Clothianidin and take other actions affecting the registration. The EPA is announcing the... organizations requesting that the EPA suspend registrations for the insecticide clothianidin for the...

  8. Distribution and concentration of suspended matter in Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator); Philpot, W.

    1977-01-01

    The author has identified the following significant results. The problem of remote sensing of suspended matter in water was analyzed in terms of the single-scattering albedo, and a semiempirical relationship between satellite radiance measurements and the concentration of suspended matter in the water was developed. The relationship was tested using data from the 7 July 1973 LANDSAT overpass of Delaware Bay with good results. Suspended sediment concentration maps for the entire Delaware Bay were prepared using radiance values extracted from LANDSAT MSS imagery and correlating them with ground truth samples collected from boats and helicopter.

  9. A novel 3D structure composed of strings of hierarchical TiO2 spheres formed on TiO2 nanobelts with high photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Jiang, Yongjian; Li, Meicheng; Song, Dandan; Li, Xiaodan; Yu, Yue

    2014-03-01

    A novel hierarchical titanium dioxide (TiO2) composite nanostructure with strings of anatase TiO2 hierarchical micro-spheres and rutile nanobelts framework (TiO2 HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO2 nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m2/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO2 HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO2 may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries.

  10. Multifunctional flexible free-standing titanate nanobelt membranes as efficient sorbents for the removal of radioactive 90Sr2+ and 137Cs+ ions and oils

    PubMed Central

    Wen, Tao; Zhao, Zhiwei; Shen, Congcong; Li, Jiaxing; Tan, Xiaoli; Zeb, Akif; Wang, Xiangke; Xu, An-Wu

    2016-01-01

    For the increasing attention focused on saving endangered environments, there is a growing need for developing membrane materials able to perform complex functions such as removing radioactive pollutants and oil spills from water. A major challenge is the scalable fabrication of membranes with good mechanical and thermal stability, superior resistance to radiation, and excellent recyclability. In this study, we constructed a multifunctional flexible free-standing sodium titanate nanobelt (Na-TNB) membrane that was assembled as advanced radiation-tainted water treatment and oil uptake. We compared the adsorption behavior of 137Cs+ and 90Sr2+ on Na-TNB membranes under various environmental conditions. The maximum adsorption coefficient value (Kd) for Sr2+ reaches 107 mL g−1. The structural collapse of the exchange materials were confirmed by XRD, FTIR and XPS spectroscopy as well as Raman analysis. The adsorption mechanism of Na-TNB membrane is clarified by forming a stable solid with the radioactive cations permanently trapped inside. Besides, the engineered multilayer membrane is exceptionally capable in selectively and rapidly adsorbing oils up to 23 times the adsorbent weight when coated with a thin layer of hydrophobic molecules. This multifunctional membrane has exceptional potential as a suitable material for next generation water treatment and separation technologies. PMID:26865116

  11. Size and Temperature Dependence of Electron Transfer between CdSe Quantum Dots and a TiO 2 Nanobelt

    SciTech Connect

    Tafen, De Nyago; Prezhdo, Oleg V.

    2015-02-24

    Understanding charge transfer reactions between quantum dots (QD) and metal oxides is fundamental for improving photocatalytic, photovoltaic and electronic devices. The complexity of these processes makes it difficult to find an optimum QD size with rapid charge injection and low recombination. We combine time-domain density functional theory with nonadiabatic molecular dynamics to investigate the size and temperature dependence of the experimentally studied electron transfer and charge recombination at CdSe QD-TiO2 nanobelt (NB) interfaces. The electron injection rate shows strong dependence on the QD size, increasing for small QDs. The rate exhibits Arrhenius temperature dependence, with the activation energy of the order of millielectronvolts. The charge recombination process occurs due to coupling of the electronic subsystem to vibrational modes of the TiO2 NB. Inelastic electron-phonon scattering happens on a picosecond time scale, with strong dependence on the QD size. Our simulations demonstrate that the electron-hole recombination rate decreases significantly as the QD size increases, in excellent agreement with experiments. The temperature dependence of the charge recombination rates can be successfully modeled within the framework of the Marcus theory through optimization of the electronic coupling and the reorganization energy. Our simulations indicate that by varying the QD size, one can modulate the photoinduced charge separation and charge recombination, fundamental aspects of the design principles for high efficiency devices.

  12. Multifunctional flexible free-standing titanate nanobelt membranes as efficient sorbents for the removal of radioactive 90Sr2+ and 137Cs+ ions and oils

    NASA Astrophysics Data System (ADS)

    Wen, Tao; Zhao, Zhiwei; Shen, Congcong; Li, Jiaxing; Tan, Xiaoli; Zeb, Akif; Wang, Xiangke; Xu, An-Wu

    2016-02-01

    For the increasing attention focused on saving endangered environments, there is a growing need for developing membrane materials able to perform complex functions such as removing radioactive pollutants and oil spills from water. A major challenge is the scalable fabrication of membranes with good mechanical and thermal stability, superior resistance to radiation, and excellent recyclability. In this study, we constructed a multifunctional flexible free-standing sodium titanate nanobelt (Na-TNB) membrane that was assembled as advanced radiation-tainted water treatment and oil uptake. We compared the adsorption behavior of 137Cs+ and 90Sr2+ on Na-TNB membranes under various environmental conditions. The maximum adsorption coefficient value (Kd) for Sr2+ reaches 107 mL g-1. The structural collapse of the exchange materials were confirmed by XRD, FTIR and XPS spectroscopy as well as Raman analysis. The adsorption mechanism of Na-TNB membrane is clarified by forming a stable solid with the radioactive cations permanently trapped inside. Besides, the engineered multilayer membrane is exceptionally capable in selectively and rapidly adsorbing oils up to 23 times the adsorbent weight when coated with a thin layer of hydrophobic molecules. This multifunctional membrane has exceptional potential as a suitable material for next generation water treatment and separation technologies.

  13. Introduction to suspended-sediment sampling

    USGS Publications Warehouse

    Nolan, K. Michael; Gray, John R.; Glysson, G. Douglas

    2005-01-01

    Knowledge of the amount and timing of sediment transport in streams is important to those directly or indirectly responsible for developing and managing water and land resources. Such data are often used to judge the health of watershed and the success or failure of activities designed to mitigate adverse impacts of sediment on streams and stream habitats. This training class presents an introduction to methods currently used by the U.S. Geological Survey (USGS) to sample suspended-sediment concentrations in streams. The presentation is narrated, but you control the pace of the presentation. If the computer you are using can view 'MPEG' videos you will be able to take advantage of videos interspersed in the presentation. A test, found at the end of the presentation, can be taken to assess how well you understood the training material. The class, which is registered as class SW4416 with the National Training Center of the USGS, should take two or three hours to complete. In order to use the presentation provided via this Web page, you will need to download a large disc images (linked below) and 'burn' it to a blank CD-ROM using a CD-ROM recorder on your computer. The presentation will only run on a Windows-based personal computer (PC). The presentation was developed using Macromedia Director MX 20041 and is contained in the file 'SIR05-5077.exe' which should autolaunch. If it does not, the presentation can be started by double-clicking on the file name. A sound card and speakers are necessary to take advantage of narrations that accompany the presentation. Text of narrations is provided, if you are unable to listen to narrations. Instructions for installing and running the presentation are included in the file 'Tutorial.htm', which is on the CD. 1 Registered Trademark: Macromedia Incorporated

  14. Ratios of total suspended solids to suspended sediment concentrations by particle size

    USGS Publications Warehouse

    Selbig, W.R.; Bannerman, R.T.

    2011-01-01

    Wet-sieving sand-sized particles from a whole storm-water sample before splitting the sample into laboratory-prepared containers can reduce bias and improve the precision of suspended-sediment concentrations (SSC). Wet-sieving, however, may alter concentrations of total suspended solids (TSS) because the analytical method used to determine TSS may not have included the sediment retained on the sieves. Measuring TSS is still commonly used by environmental managers as a regulatory metric for solids in storm water. For this reason, a new method of correlating concentrations of TSS and SSC by particle size was used to develop a series of correction factors for SSC as a means to estimate TSS. In general, differences between TSS and SSC increased with greater particle size and higher sand content. Median correction factors to SSC ranged from 0.29 for particles larger than 500m to 0.85 for particles measuring from 32 to 63m. Great variability was observed in each fraction-a result of varying amounts of organic matter in the samples. Wide variability in organic content could reduce the transferability of the correction factors. ?? 2011 American Society of Civil Engineers.

  15. Estimation of suspended-sediment rating curves and mean suspended-sediment loads

    USGS Publications Warehouse

    Crawford, Charles G.

    1991-01-01

    A simulation study was done to evaluate: (1) the accuracy and precision of parameter estimates for the bias-corrected, transformed-linear and non-linear models obtained by the method of least squares; (2) the accuracy of mean suspended-sediment loads calculated by the flow-duration, rating-curve method using model parameters obtained by the alternative methods. Parameter estimates obtained by least squares for the bias-corrected, transformed-linear model were considerably more precise than those obtained for the non-linear or weighted non-linear model. The accuracy of parameter estimates obtained for the biascorrected, transformed-linear and weighted non-linear model was similar and was much greater than the accuracy obtained by non-linear least squares. The improved parameter estimates obtained by the biascorrected, transformed-linear or weighted non-linear model yield estimates of mean suspended-sediment load calculated by the flow-duration, rating-curve method that are more accurate and precise than those obtained for the non-linear model.

  16. 31 CFR 8.51 - Authority to disbar or suspend.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... BUREAU OF ALCOHOL, TOBACCO AND FIREARMS Disciplinary Proceedings § 8.51 Authority to disbar or suspend... or prospective client, by word, circular, letter, or by advertisement. (Sec. 3, 23 Stat. 258 (31...

  17. Detail of window treatment, suspended radiators, and fluorescent lights, prop ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of window treatment, suspended radiators, and fluorescent lights, prop shop. View to east. - San Bernardino Valley College, Auditorium, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA

  18. 16. DETAIL VIEW OF NORTHWEST SIDE LOADING DOCKS, SHOWING SUSPENDER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. DETAIL VIEW OF NORTHWEST SIDE LOADING DOCKS, SHOWING SUSPENDER BARS AND ORIGINAL SHIPLAP SIDING - Oakland Army Base, Transit Shed, East of Dunkirk Street & South of Burma Road, Oakland, Alameda County, CA

  19. 6. INTERIOR VIEW OF TYPICAL OPERATING ROOM; NOTE APPARATUS SUSPENDED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. INTERIOR VIEW OF TYPICAL OPERATING ROOM; NOTE APPARATUS SUSPENDED FROM CEILING & REMAINING COPPER STRIPS IN FLOOR - Fort McCoy, Building No. T-1032, North side of South Tenth Avenue, Block 10, Sparta, Monroe County, WI

  20. EPA Suspended Work on a Pesticide Container Recycling Proposed Rule

    EPA Pesticide Factsheets

    EPA suspended work on the proposed container recycling regulation as of July 2008 after receiving a letter from OMB, because we did not have data that specifically addressed the concern OMB identified.

  1. Astronaut Curtis Brown suspended by simulated parachute gear during training

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Curtis L. Brown, STS-66 pilot, is suspended by a simulated parachute gear during an emergency bailout training exercise in JSC's Weightless Environment Training Facility (WETF). He is wearing his orange launch and entry suit.

  2. 38. INTERIOR VIEW OF TANK. Suspended wooden platform obscures bottom ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. INTERIOR VIEW OF TANK. Suspended wooden platform obscures bottom of tank No date - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  3. 12. VIEW FROM SOUTHWEST OF STEPS SUSPENDED OVER THE STREAM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW FROM SOUTHWEST OF STEPS SUSPENDED OVER THE STREAM WITH PLUNGE POOL AND 'MOTHER AND CHILD' BRONZE SCULPTURE BY JACQUES LIPCHITZ IN BACKGROUND. - Fallingwater, State Route 381 (Stewart Township), Ohiopyle, Fayette County, PA

  4. 13. TURNING DEVICE SUSPENDED FROM, AND LIFTED BY THE OVERHEAD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. TURNING DEVICE SUSPENDED FROM, AND LIFTED BY THE OVERHEAD CRANE SYSTEM EAST OF No. 1 PRESS. - U.S. Steel Homestead Works, Press Shop No. 1, Along Monongahela River, Homestead, Allegheny County, PA

  5. 14. CLOSEUP OF TURNING DEVICE SUSPENDED FROM, AND LIFTED BY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. CLOSE-UP OF TURNING DEVICE SUSPENDED FROM, AND LIFTED BY THE OVERHEAD CRANE SYSTEM EAST OF No. 1 PRESS. - U.S. Steel Homestead Works, Press Shop No. 1, Along Monongahela River, Homestead, Allegheny County, PA

  6. Suspended-sediment and suspended-sand concentrations and loads for selected streams in the Mississippi River Basin, 1940-2009

    USGS Publications Warehouse

    Heimann, David C.; Cline, Teri L.; Glaspie, Lori M.

    2011-01-01

    This report presents suspended-sediment concentration and streamflow data, describes load-estimation techniques used in the computation of annual suspended-sediment loads, and presents annual suspended-sediment loads for 48 streamgaging stations within the Mississippi River Basin. Available published, unpublished, and computed annual total suspended-sediment and suspended-sand loads are presented for water years 1940 through 2009. When previously published annual loads were not available, total suspended-sediment and sand loads were computed using available data for water years 1949 through 2009. A table of suspended-sediment concentration and daily mean streamflow data used in the computation of annual loads is presented along with a table of compiled and computed annual suspended-sediment and suspended-sand loads, annual streamflows, and flow-weighted concentrations for the 48 stations.

  7. Satellite power using a magnetically suspended flywheel stack

    NASA Technical Reports Server (NTRS)

    Kirk, James A.; Anand, Davinder K.

    1988-01-01

    Research activities with magnetically suspended flywheels are reported. The purpose of the effort is to critically examine and further the development of all the key technologies which impact the inertial energy storage system. The results presented discuss the concept of a magnetically suspended flywheel as it applies to a 500 Watt-hour energy storage system. The proposed system is currently under hardware development and is based upon two pancake magnetic bearings arranged in a vertical stack.

  8. Drawing suspended polymer micro-/nanofibers using glass micropipettes

    NASA Astrophysics Data System (ADS)

    Nain, Amrinder S.; Wong, Joanna C.; Amon, Cristina; Sitti, Metin

    2006-10-01

    This letter proposes a method for fabricating suspended micro-/nanoscale polymer fibers continuously, in which polymeric micro-/nanofibers are formed by drawing and solidification of a viscous liquid polymer solution which is pumped through a glass micropipette. By controlling the drawing parameters, this method is demonstrated to form networks of suspended fibers having amorphous internal structure and uniform diameters from micrometers down to sub-50-nm for different molecular weights of polystyrene dissolved in xylene.

  9. Suspended sediment apportionment in a South-Korean mountain catchment

    NASA Astrophysics Data System (ADS)

    Birkholz, Axel; Meusburger, Katrin; Park, Ji-Hyung; Alewell, Christine

    2016-04-01

    Due to the rapid agricultural expansion and intensification during the last decades in South-Korea, large areas of hill slope forests were transformed to paddies and vegetable fields. The intensive agriculture and the easily erodible soils in our catchment are a major reason for the increased erosion causing suspended sediments to infiltrate into the close drinking water reservoir. The drinking water reservoir Lake Soyang provides water supply for over ten million people in Seoul. Landscape managers need to know the exact origin of these sediments before they can create landscape amelioration schemes. We applied a compound-specific stable isotope (CSSI) approach (Alewell et al., 2015) to apportion the sources of the suspended sediments between forest and agricultural soil contribution to the suspended sediments in a different catchment and applied the same approach to identify and quantify the different sources of the suspended sediments in the river(s) contributing to Lake Soyang. We sampled eight soil sites within the catchment considering the different landuse types forest, rice paddies, maize and vegetables. Suspended sediments were sampled at three outlets of the different sub-catchments. Soils and suspended sediments are analysed for bulk carbon and nitrogen isotopes, compound-specific carbon isotopes of plant-wax derived long-chain fatty acids and long-chain n-alkanes. Fatty acid and alkane isotopes are then used in mixing calculations and the mixing model software IsoSource to find out the contribution of the different source soils to the suspended sediments. We present first data of the source soils and the suspended sediments. C. Alewell, A. Birkholz, K. Meusburger, Y. Schindler-Wildhaber, L. Mabit, 2015. Sediment source attribution from multiple land use systems with CSIA. Biogeosciences Discuss. 12: 14245-14269.

  10. Suspended sediment fluxes in the Humber catchment, UK

    NASA Astrophysics Data System (ADS)

    Wass, Paul D.; Leeks, Graham J. L.

    1999-05-01

    An extensive sediment monitoring network was established within the LOIS programme, involving 10 of the main tributaries of the River Humber (UK). Its primary purpose was to measure the flux of suspended sediment to the estuary. A turbidity monitoring system was developed to provide a continuous record of suspended sediment concentration in the rivers, from which the fluxes were calculated. Linear relationships were established between suspended sediment concentration and turbidity (with slopes varying from 0·89 to 1·69) to enable the conversion of nephelometric turbidity [NTU] to suspended sediment concentration [mg l-1]. Potential uncertainties were identified and quantified. The suspended sediment flux to the Humber (November 1994-October 1997) was calculated to be 699 861 t, equivalent to a yield of 15 t km-2 yr-1. Large temporal and spatial variations in the flux were measured during the monitoring period, in response to factors such as climate, land use, catchment scale, deposition and reservoir trapment. The particle size composition of the suspended sediment was measured and found to vary little, except at very high discharges, when it coarsened. The organic content of the sediment was found to be directly related to the discharge of sewage effluent to the rivers.

  11. Comparability of suspended-sediment concentration and total suspended-solids data for two sites on the L'Anguille River, Arkansas, 2001 to 2003

    USGS Publications Warehouse

    Galloway, Joel M.; Evans, Dennis A.; Green, W. Reed

    2005-01-01

    Suspended-sediment concentration and total suspended solids data collected with automatic pumping samplers at the L'Anguille River near Colt and the L'Anguille River at Palestine, Arkansas, August 2001 to October 2003 were compared using ordinary least squares regression analyses to determine the relation between the two datasets for each of the two sites. The purpose of this report is to describe the suspended-sediment concentration and total suspended-solids data and examine the comparability of the two datasets for each site. Suspended-sediment concentration and total suspended solids data for the L'Anguille River varied spatially and temporally from August 2001 to October 2003. The site at the L'Anguille River at Palestine represents a larger portion of the L'Anguille River Basin than the site near Colt, and generally had higher median suspended-sediment concentration and total suspended solids and greater ranges in values. The differences between suspended-sediment concentration and total suspended solids data for the L'Anguille River near Colt appeared inversely related to streamflow and not related to time. The relation between suspended-sediment concentration and total suspended solids at the L'Anguille River at Palestine was more variable than at Colt and did not appear to have a relation with flow or time. The relation between suspended-sediment concentration and total suspended solids for the L'Anguille River near Colt shows that total suspended solids increased proportionally as suspended-sediment concentration increased. However, the relation between suspended-sediment concentration and total suspended solids for the L'Anguille River at Palestine showed total suspended solids increased less proportionally as suspended-sediment concentration increased compared to the L'Anguille River near Colt. Differences between the two analytical methods may partially explain differences between the suspended-sediment concentration and total suspended solids data at

  12. 33 CFR 159.126a - Suspended solids test: Type II devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Suspended solids test: Type II... Suspended solids test: Type II devices. During the sewage processing test (§ 159.121) 40 effluent samples... suspended solids in accordance with 40 CFR Part 136. The arithmetic mean of the total suspended solids in...

  13. 33 CFR 159.126a - Suspended solids test: Type II devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Suspended solids test: Type II... Suspended solids test: Type II devices. During the sewage processing test (§ 159.121) 40 effluent samples... suspended solids in accordance with 40 CFR part 136. The arithmetic mean of the total suspended solids in...

  14. Suspended sediment transport under estuarine tidal channel conditions

    USGS Publications Warehouse

    Sternberg, R.W.; Kranck, K.; Cacchione, D.A.; Drake, D.E.

    1988-01-01

    A modified version of the GEOPROBE tripod has been used to monitor flow conditions and suspended sediment distribution in the bottom boundary layer of a tidal channel within San Francisco Bay, California. Measurements were made every 15 minutes over three successive tidal cycles. They included mean velocity profiles from four electromagnetic current meters within 1 m of the seabed; mean suspended sediment concentration profiles from seven miniature nephelometers operated within 1 m of the seabed; near-bottom pressure fluctuations; vertical temperature gradient; and bottom photographs. Additionally, suspended sediment was sampled from four levels within 1 m of the seabed three times during each successive flood and ebb cycle. While the instrument was deployed, STD-nephelometer measurements were made throughout the water column, water samples were collected each 1-2 hours, and bottom sediment was sampled at the deployment site. From these measurements, estimates were made of particle settling velocity (ws) from size distributions of the suspended sediment, friction velocity (U*) from the velocity profiles, and reference concentration (Ca) was measured at z = 20 cm. These parameters were used in the suspended sediment distribution equations to evaluate their ability to predict the observed suspended sediment profiles. Three suspended sediment particle conditions were evaluated: (1) individual particle size in the 4-11 ?? (62.5-0.5 ??m) range with the reference concentration Ca at z = 20 cm (C??), (2) individual particle size in the 4-6 ?? size range, flocs representing the 7-11 ?? size range with the reference concentration Ca at z = 20 cm (Cf), and (3) individual particle size in the 4-6 ?? size range, flocs representing the 7-11 ?? size range with the reference concentration predicted as a function of the bed sediment size distribution and the square of the excess shear stress. In addition, computations of particle flux were made in order to show vertical variations

  15. Cathodoluminescence characterization of suspended GaN nanomembranes

    NASA Astrophysics Data System (ADS)

    Stevens-Kalceff, M. A.; Tiginyanu, I. M.; Popa, V.; Braniste, T.; Brenner, P.

    2013-07-01

    Continuous suspended ˜15 nm thick gallium nitride (GaN) nano-membranes have been investigated using cathodoluminescence microanalysis. The GaN nanomembranes are fabricated by focused ion beam (FIB) pre-treatment of GaN epilayer surfaces followed by photoelectrochemical (PEC) etching. CL microanalysis enables high sensitivity, nanoscale spatial resolution detection of impurities, and defects, and is associated with key features of the suspended GaN nano-membranes. CL spectra and images of the suspended nano-membranes reveal the broad emission band at ˜2.2 eV which is associated with deep acceptor states and the near edge emission at ˜3.4 eV which is associated with free exciton transitions at 295 K. The near edge emission can be resolved into two components, one associated with emission from the nanomembrane and the other associated with CL from underlying GaN transmitted through the nanomembrane. CL spectroscopy gives insight into the physical properties and optical quality of the suspended GaN nano-membranes. Blue shift of the CL near band edge emission indicates that the suspended GaN nanomembranes exhibit the combined effects of quantum confinement and strain.

  16. Three human cell types respond to multi-walled carbon nanotubes and titanium dioxide nanobelts with cell-specific transcriptomic and proteomic expression patterns

    PubMed Central

    Tilton, Susan C.; Karin, Norman J.; Tolic, Ana; Xie, Yumei; Lai, Xianyin; Hamilton, Raymond F.; Waters, Katrina M.; Holian, Andrij; Witzmann, Frank A.; Orr, Galya

    2014-01-01

    The growing use of engineered nanoparticles (NPs) in commercial and medical applications raises the urgent need for tools that can predict NP toxicity. We conducted global transcriptome and proteome analyses of three human cell types, exposed to two high aspect ratio NP types, to identify patterns of expression that might indicate high vs. low NP toxicity. Three cell types representing the most common routes of human exposure to NPs, including macrophage like (THP-1), small airway epithelial (SAE), and intestinal (Caco-2/HT29-MTX) cells, were exposed to TiO2 nanobelts (TiO2-NB; high toxicity) and multi-walled carbon nanotubes (MWCNT; low toxicity) at low (10 μg/ml) and high (100 μg/ml) concentrations for 1 and 24 h. Unique patterns of gene and protein expressions were identified for each cell type, with no differentially expressed (p<0.05, 1.5-fold change) genes or proteins overlapping across all three cell types. While unique to each cell-type, the early response was primarily independent of NP type, showing similar expression patterns in response to both TiO2-NB and MWCNT. The early response might therefore indicate a general response to insult. In contrast, the 24 h response was unique to each NP type. The most significantly (p<0.05) enriched biological processes in THP-1 cells indicated TiO2-NB regulation of pathways associated with inflammation, apoptosis, cell cycle arrest, DNA replication stress and genomic instability, while MWCNT regulated pathways indicating increased cell proliferation, DNA repair and anti-apoptosis. These two distinct sets of biological pathways might therefore underlie cellular responses to high and low NP toxicity, respectively. PMID:23659652

  17. Three Human Cell Types Respond to Multi-Walled Carbon Nanotubes and Titanium Dioxide Nanobelts with Cell-Specific Transcriptomic and Proteomic Expression Patterns.

    SciTech Connect

    Tilton, Susan C.; Karin, Norman J.; Tolic, Ana; Xie, Yumei; Lai, Xianyin; Hamilton, Raymond F.; Waters, Katrina M.; Holian, Andrij; Witzmann, Frank A.; Orr, Galya

    2014-08-01

    The growing use of engineered nanoparticles (NPs) in commercial and medical applications raises the urgent need for tools that can predict NP toxicity. Global transcriptome and proteome analyses were conducted on three human cell types, exposed to two high aspect ratio NP types, to identify patterns of expression that might indicate high versus low NP toxicity. Three cell types representing the most common routes of human exposure to NPs, including macrophage-like (THP-1), small airway epithelial and intestinal (Caco-2/HT29-MTX) cells, were exposed to TiO2 nanobelts (TiO2-NB; high toxicity) and multi-walled carbon nanotubes (MWCNT; low toxicity) at low (10 µg/mL) and high (100 µg/mL) concentrations for 1 and 24 h. Unique patterns of gene and protein expressions were identified for each cell type, with no differentially expressed (p < 0.05, 1.5-fold change) genes or proteins overlapping across all three cell types. While unique to each cell type, the early response was primarily independent of NP type, showing similar expression patterns in response to both TiO2-NB and MWCNT. The early response might, therefore, indicate a general response to insult. In contrast, the 24 h response was unique to each NP type. The most significantly (p < 0.05) enriched biological processes in THP-1 cells indicated TiO2-NB regulation of pathways associated with inflammation, apoptosis, cell cycle arrest, DNA replication stress and genomic instability, while MWCNT-regulated pathways indicated increased cell proliferation, DNA repair and anti-apoptosis. These two distinct sets of biological pathways might, therefore, underlie cellular responses to high and low NP toxicity, respectively.

  18. Mapping the nanomechanical properties of graphene suspended on silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Osváth, Z.; Gergely-Fülöp, E.; Deák, A.; Hwang, C.; Biró, L. P.

    2016-09-01

    Using nanoparticles to impart extrinsic rippling in graphene is a relatively new method to induce strain and to tailor the properties of graphene. Here we study the structure and elastic properties of graphene grown by chemical vapour deposition and transferred onto a continuous layer of SiO2 nanoparticles with diameters of around 25 nm, prepared by Langmuir-Blodgett technique on Si substrate. We show that the transferred graphene follows only roughly the morphology induced by nanoparticles. The graphene membrane parts bridging the nanoparticles are suspended and their adhesion to the AFM tip is larger compared to that of supported graphene parts. These suspended graphene regions can be deformed with forces of the order of 10 nN. The elastic modulus of graphene was determined from indentation measurements performed on suspended membrane regions with diameters in the 100 nm range.

  19. Space charge neutralization by electron-transparent suspended graphene.

    PubMed

    Srisonphan, Siwapon; Kim, Myungji; Kim, Hong Koo

    2014-01-20

    Graphene possesses many fascinating properties originating from the manifold potential for interactions at electronic, atomic, or molecular levels. Here we report measurement of electron transparency and hole charge induction response of a suspended graphene anode on top of a void channel formed in a SiO2/Si substrate. A two-dimensional (2D) electron gas induced at the oxide interface emits into air and makes a ballistic transport toward the suspended graphene. A small fraction (>~0.1%) of impinging electrons are captured at the edge of 2D hole system in graphene, demonstrating good transparency to very low energy (<3 eV) electrons. The hole charges induced in the suspended graphene anode have the effect of neutralizing the electron space charge in the void channel. This charge compensation dramatically enhances 2D electron gas emission at cathode to the level far surpassing the Child-Langmuir's space-charge-limited emission.

  20. Flywheel Energy Storage System Suspended by Hybrid Magnetic Bearing

    NASA Astrophysics Data System (ADS)

    Owusu-Ansah, Prince; Hu, Yefa; Misbawu, Adam

    This work presents a prototype flywheel energy storage system (FESS) suspended by hybrid magnetic bearing (HMB) rotating at a speed of 20000rpm with a maximum storage power capacity of 30W with a maximum tip speed of 300m/s. The design presented is an improvement of most existing FESS, as the design incorporates a unique feature in that the upper and the lower rotor and stator core are tapered which enhances larger thrust and much lower radial force to be exerted on the system. Without any adverse effect being experienced by the model. The work also focuses on the description of developing a prototype FESS suspended by HMB using solid works as a basis of developing in the nearer future a more improved FESS suspended by HMB capable of injecting the ever increasing high energy demand situation in the 21st century and beyond.

  1. Nano-superconducting quantum interference devices with suspended junctions

    SciTech Connect

    Hazra, D.; Hasselbach, K.; Kirtley, J. R.

    2014-04-14

    Nano-Superconducting Quantum Interference Devices (nano-SQUIDs) are usually fabricated from a single layer of either Nb or Al. We describe here a simple method for fabricating suspended nano-bridges in Nb/Al thin-film bilayers. We use these suspended bridges, which act as Josephson weak links, to fabricate nano-SQUIDs which show critical current oscillations at temperatures up to 1.5 K and magnetic flux densities up to over 20 mT. These nano-SQUIDs exhibit flux modulation depths intermediate between all-Al and all-Nb devices, with some of the desirable characteristics of both. The suspended geometry is attractive for magnetic single nanoparticle measurements.

  2. System for concentrating and analyzing particles suspended in a fluid

    DOEpatents

    Fiechtner, Gregory J.; Cummings, Eric B.; Singh, Anup K.

    2011-04-26

    Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

  3. Tracing suspended sediment sources in catchments and river systems.

    PubMed

    Walling, D E

    2005-05-15

    Recent years have seen a growing awareness of the wider environmental significance of the suspended sediment loads transported by rivers and streams. This includes the importance of fine sediment in the transport of nutrients and contaminants, including phosphorus (P). Sediment source exerts a key control on the physical and geochemical properties of suspended sediment, including its P content, and will also influence the potential for implementing effective sediment and diffuse source pollution control strategies. Information on suspended sediment source, defined in terms of both source type and spatial origin, is therefore increasingly needed. Such information is difficult to obtain using traditional monitoring techniques, but source tracing or fingerprinting techniques afford a valuable and effective alternative approach to establish the relative importance of potential sediment sources. This contribution reviews the development of source fingerprinting techniques, presents several examples of their application in UK catchments and discusses the need for future development of the approach and the potential for extending its application.

  4. Optimal estimation of suspended-sediment concentrations in streams

    USGS Publications Warehouse

    Holtschlag, D.J.

    2001-01-01

    Optimal estimators are developed for computation of suspended-sediment concentrations in streams. The estimators are a function of parameters, computed by use of generalized least squares, which simultaneously account for effects of streamflow, seasonal variations in average sediment concentrations, a dynamic error component, and the uncertainty in concentration measurements. The parameters are used in a Kalman filter for on-line estimation and an associated smoother for off-line estimation of suspended-sediment concentrations. The accuracies of the optimal estimators are compared with alternative time-averaging interpolators and flow-weighting regression estimators by use of long-term daily-mean suspended-sediment concentration and streamflow data from 10 sites within the United States. For sampling intervals from 3 to 48 days, the standard errors of on-line and off-line optimal estimators ranged from 52.7 to 107%, and from 39.5 to 93.0%, respectively. The corresponding standard errors of linear and cubic-spline interpolators ranged from 48.8 to 158%, and from 50.6 to 176%, respectively. The standard errors of simple and multiple regression estimators, which did not vary with the sampling interval, were 124 and 105%, respectively. Thus, the optimal off-line estimator (Kalman smoother) had the lowest error characteristics of those evaluated. Because suspended-sediment concentrations are typically measured at less than 3-day intervals, use of optimal estimators will likely result in significant improvements in the accuracy of continuous suspended-sediment concentration records. Additional research on the integration of direct suspended-sediment concentration measurements and optimal estimators applied at hourly or shorter intervals is needed.

  5. Sources of suspended sediment in the Lower Roanoke River, NC

    NASA Astrophysics Data System (ADS)

    Jalowska, A. M.; McKee, B. A.; Rodriguez, A. B.; Laceby, J. P.

    2015-12-01

    The Lower Roanoke River, NC, extends 220 km from the fall line to the bayhead delta front in the Albemarle Sound. The Lower Roanoke is almost completely disconnected from the upper reaches by a series of dams, with the furthest downstream dam located at the fall line. The dams effectively restrict the suspended sediment delivery from headwaters, making soils and sediments from the Lower Roanoke River basin, the sole source of suspended sediment. In flow-regulated rivers, bank erosion, especially mass wasting, is the major contributor to the suspended matter. Additional sources of the suspended sediment considered in this study are river channel, surface soils, floodplain surface sediments, and erosion of the delta front and prodelta. Here, we examine spatial and temporal variations in those sources. This study combined the use of flow and grain size data with a sediment fingerprinting method, to examine the contribution of surface and subsurface sediments to the observed suspended sediment load along the Lower Roanoke River. The fingerprinting method utilized radionuclide tracers 210Pb (natural atmospheric fallout), and 137Cs (produced by thermonuclear bomb testing). The contributions of surface and subsurface sources to the suspended sediment were calculated with 95% confidence intervals using a Monte-Carlo numerical mixing model. Our results show that with decreasing river slope and changing hydrography along the river, the contribution of surface sediments increases and becomes a main source of sediments in the Roanoke bayhead delta. At the river mouth, the surface sediment contribution decreases and is replaced by sediments eroded from the delta front and prodelta. The area of high surface sediment contribution is within the middle and upper parts of the delta, which are considered net depositional. Our study demonstrates that floodplains, often regarded to be a sediment sink, are also a sediment source, and they should be factored into sediment, carbon and

  6. Colorimetry Technique for Scalable Characterization of Suspended Graphene.

    PubMed

    Cartamil-Bueno, Santiago J; Steeneken, Peter G; Centeno, Alba; Zurutuza, Amaia; van der Zant, Herre S J; Houri, Samer

    2016-11-09

    Previous statistical studies on the mechanical properties of chemical-vapor-deposited (CVD) suspended graphene membranes have been performed by means of measuring individual devices or with techniques that affect the material. Here, we present a colorimetry technique as a parallel, noninvasive, and affordable way of characterizing suspended graphene devices. We exploit Newton's rings interference patterns to study the deformation of a double-layer graphene drum 13.2 μm in diameter when a pressure step is applied. By studying the time evolution of the deformation, we find that filling the drum cavity with air is 2-5 times slower than when it is purged.

  7. Effect of strain on thermoelectric power of suspended graphene

    SciTech Connect

    Vaidya, R. G.; Sankeshwar, N. S. Mulimani, B. G.

    2013-12-04

    Thermoelectric power, S, of suspended graphene in the presence of strain is investigated. The electrons are considered to be scattered by in-plane and flexural phonons. The dominant contribution to S of non-strained and strained suspended graphene (SG) is found to be from the phonon drag component, S{sub g} for T < 90K. For T > 150 K contribution from diffusion thermopower becomes important. The effect of strain is found to be suppress S{sub d} and to alter its behavior, the effect being larger at higher temperatures.

  8. Dynamic transport of suspended sediment by solitary wave: Experimental study

    NASA Astrophysics Data System (ADS)

    cho, JaeNam; Kim, DongHyun; Hwang, KyuNam; Lee, SeungOh

    2016-04-01

    Solitary waves are able to transport a large amount of suspended sediment when approaching on the beach, which sometimes causes - serious beach erosion, especially in the east and south coastal lines in Korea. But it has rarely been known about the method how to evaluate or estimate the amount of beach erosion caused by solitary waves. Experimental assessment is necessary to comprehend the process of sediment transport on a slope. The prismatic rectangular channel is 12 m long, 0.8 m wide, and 0.75 m high. A sluice gate is applied at prismatic channel in order to produce the solitary waves. Upstream water depth is more than channel water depth and the sluice gate is suddenly opened to simulate conditions of solitary waves. A sand slope with a 1/6 and a sediment thickness is 0.03 m. The experimental sediments are used anthracite (d_50=1.547 mm ,C_u=1.38) and Jumoonjin sand (d_50=0.627 mm ,C_u=1.68). Specific laboratory equipment are designed to collect suspended sediment samples at the same time along the wave propagation at 5 points with evenly space. Each amount of sampling is approximately 25 ml and they are completely dried in oven over 24 hours according to the USGS (Guideline and standard techniques and method 3-C4). Two video cameras (Model No. : Sony, HDR-XR550) are mounted for capturing images at top and side-view when the processes of solitary wave and run up/down on slope. Also, this study are analyzed the correlation between Suspended sediment concentration and turbidity. Also, this study are analyzed the correlation between suspended sediment concentration and turbidity. Turbidity is used to verify suspended sediment concentration. Dimensionless analyses of experimental results carried out in this study. One dimensionless parameter is expressed with pressure of solitary wave on a slope to suspended sediment concentration, which is concerned about lifting force. The other is relate to drag force presenting with run up/down velocity on a slope and

  9. Design of a LC-tuned magnetically suspended rotating gyroscope

    NASA Astrophysics Data System (ADS)

    Jin, Lichuan; Zhang, Huaiwu; Zhong, Zhiyong

    2011-04-01

    A inductor-capacitor (LC) tuned magnetically suspended rotating gyroscope prototype is designed and analyzed. High permeability ferrite cores are used for providing suspension force, and the rotation system is designed using the switched reluctance motor (SRM) principle. According to the LC-tuned principle, magnetic suspension force expression has been derived. The electromagnetic properties of the gyroscope are simulated by the Ansoft Maxwell software. And our result is expected to be able to serve as a prototype of micro-electromechanical system (MEMS) magnetically suspended rotating gyroscope in future practical applications.

  10. 14 CFR 221.211 - Cancellation of suspended matter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Cancellation of suspended matter. 221.211 Section 221.211 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION... matter. When, pursuant to an order of the Department, the cancellation of rules, fares, charges, or...

  11. 14 CFR 221.211 - Cancellation of suspended matter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Cancellation of suspended matter. 221.211 Section 221.211 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION... matter. When, pursuant to an order of the Department, the cancellation of rules, fares, charges, or...

  12. 14 CFR 221.211 - Cancellation of suspended matter.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Cancellation of suspended matter. 221.211 Section 221.211 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION... matter. When, pursuant to an order of the Department, the cancellation of rules, fares, charges, or...

  13. 14 CFR 221.211 - Cancellation of suspended matter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Cancellation of suspended matter. 221.211 Section 221.211 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION... matter. When, pursuant to an order of the Department, the cancellation of rules, fares, charges, or...

  14. 14 CFR 221.211 - Cancellation of suspended matter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Cancellation of suspended matter. 221.211 Section 221.211 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION... matter. When, pursuant to an order of the Department, the cancellation of rules, fares, charges, or...

  15. Simultaneous removal of ammonium and suspended solids in multipurpose filters.

    PubMed

    Alkas, Deniz; Baykal, Bilsen Beler; Kinaci, Cumali

    2012-06-01

    A multipurpose filter in which sand and clinoptilolite are used together as filter material is suggested for the simultaneous removal of suspended solids and ammonium in one single unit. The capacity of the clinoptilolite used was determined as 10.4 mg/g for 20 mg/l initial ammonium concentration. In addition, a packed column ion exchanger with clinoptilolite and a classical sand filter were also investigated for comparison. Ammonium and suspended solids removal rates were observed and compared for all columns. The results of the column analysis have revealed that the ammonium removal rate, which was only 20% in the sand column, was increased to 100% by replacing 50% of the sand with clinoptilolite; similarly, the suspended solids removal, which was only 17% in the clinoptilolite column, was increased to 75% by replacing 50% of the clinoptilolite with sand. As such, when ion exchange and filtration processes were carried out in a multipurpose column, high removals for both parameters could be obtained simultaneously. Multipurpose columns could be an alternative both for the upgrading of existing treatment plants or for new plants for simultaneous removal of ammonium and suspended solids, giving considerable savings in terms of land requirements.

  16. Opportunities Suspended: The Disparate Impact of Disciplinary Exclusion from School

    ERIC Educational Resources Information Center

    Losen, Daniel J.; Gillespie, Jonathan

    2012-01-01

    Well over three million children, K-12, are estimated to have lost instructional "seat time" in 2009-2010 because they were suspended from school, often with no guarantee of adult supervision outside the school. That's about the number of children it would take to fill every seat in every major league baseball park and every NFL stadium…

  17. Is There an Educational Penalty for Being Suspended from School?

    ERIC Educational Resources Information Center

    Cobb-Clark, Deborah A.; Kassenboehmer, Sonja C.; Le, Trinh; McVicar, Duncan; Zhang, Rong

    2015-01-01

    Suspension from school is a commonly used, yet controversial, school disciplinary measure. This paper uses unique survey data to estimate the impact of suspension on the educational outcomes of those suspended. It finds that while suspension is strongly associated with educational outcomes, the relationship is unlikely to be causal, but rather…

  18. Suspended sediments of the modern Amazon and Orinoco rivers

    USGS Publications Warehouse

    Meade, R.H.

    1994-01-01

    The Amazon and Orinoco Rivers are massive transcontinental conveyance systems for suspended sediment. They derive about 90% of their sediment from the Andes that support their western headwaters, transport it for thousands of kilometers across the breadth of the continent and deposit it in the coastal zones of the Atlantic. At their points of maximum suspended-sediment discharge, the Amazon transports an average of 1100-1300 ?? 106 tons per year and the Orinoco transports about 150 ?? 106 tons per year. Relations of sediment discharge to water discharge are complicated by unusual patterns of seasonal storage and remobilization, increased storage and reduced transport of sediment in the middle Orinoco during periods of peak water discharge, and storage of suspended sediment in the lower Amazon during rising discharge and resuspension during falling discharge. Spatial distributions of suspended sediment in cross-sections of both rivers are typically heterogeneous, not only in the vertical sense but also in the lateral. The cross-channel mixing of tributary inputs into the mainstem waters is a slow process that requires several hundred kilometers of downriver transport to complete. Considerable fine-grained sediment is exchanged between rivers and floodplains by the combination of overbank deposition and bank erosion. ?? 1994.

  19. Suspended onion particles and potential corneal injury in onion harvesters.

    PubMed

    Hwang, Yaw-Huei; Chou, En-Ju; Chang, Ching-Wen; Chen, Chih-Chieh; Ho, Chi-Kung; Chou, Chih-Liang; Lee, Zhih-Young; Tseng, Chi-Ting

    2002-01-01

    The authors suspected that suspended onion particles contributed to corneal ulcers in onion harvesters in southern Taiwan. In the present study, the authors used manikins to study suspended onion particles in fields in an effort to simulate typical conditions experienced by onion harvesters. An animal eye-exposure simulation study was also performed by the authors, who impacted suspended soil grains or onion particles onto the corneas of guinea pigs via aerosol generated from the Palas dispersion nozzle. The average size of 25.9 pm for suspended particles collected during the digging of onions was the largest one of those for various harvesting activities. Some onion skin flakes were found in samples obtained from gathering and packing activities; the typical flake size was approximately 3.5 x 2.5 mm2. The results of the animal study indicated that the size of soil grains has a demonstrable effect on the severity of corneal injury (p = .009). With respect to onion skin flakes, wind velocity was also associated significantly with the occurrence of corneal injury (p = .0004). A wind velocity threshold of 7 m/sec is recommended for the maintenance of safety, and if the wind speed exceeds this threshold level, workers should not engage in harvesting activities. Furthermore, use of appropriately designed goggles is necessary for the protection of onion harvesters who work in high-wind conditions.

  20. Suspended sediment modeling using genetic programming and soft computing techniques

    NASA Astrophysics Data System (ADS)

    Kisi, Ozgur; Dailr, Ali Hosseinzadeh; Cimen, Mesut; Shiri, Jalal

    2012-07-01

    SummaryModeling suspended sediment load is an important factor in water resources engineering as it crucially affects the design and management of water resources structures. In this study the genetic programming (GP) technique was applied for estimating the daily suspended sediment load in two stations in Cumberland River in U.S. Daily flow and sediment data from 1972 to 1989 were used to train and test the applied genetic programming models. The effect of various GP operators on sediment load estimation was investigated. The optimal fitness function, operator functions, linking function and learning algorithm were obtained for modeling daily suspended sediment. The GP estimates were compared with those of the Adaptive Neuro-Fuzzy Inference System (ANFIS), Artificial Neural Networks (ANNs) and Support Vector Machine (SVM) results, in term of coefficient of determination, mean absolute error, coefficient of residual mass and variance accounted for. The comparison results indicated that the GP is superior to the ANFIS, ANN and SVM models in estimating daily suspended sediment load.

  1. Nonlinear effects generation in suspended core chalcogenide fibre

    NASA Astrophysics Data System (ADS)

    El-Amraoui, M.; Duhant, M.; Desevedavy, F.; Renard, W.; Canat, G.; Gadret, G.; Jules, J.-C.; Fatome, J.; Kibler, B.; Renversez, G.; Troles, J.; Brilland, L.; Messaddeq, Y.; Smektala, F.

    2011-05-01

    In this work we report our achievements in the elaboration and optical characterizations of low-losses suspended core optical fibers elaborated from As2S3 glass. For preforms elaboration, alternatively to other processes like the stack and draw or extrusion, we use a process based on mechanical drilling. The drawing of these drilled performs into fibers allows reaching a suspended core geometry, in which a 2 μm diameter core is linked to the fiber clad region by three supporting struts. The different fibers that have been drawn show losses close to 0.9 dB/m at 1.55 μm. The suspended core waveguide geometry has also an efficient influence on the chromatic dispersion and allows its management. Indeed, the zero dispersion wavelength, which is around 5 μm in the bulk glass, is calculated to be shifted towards around 2μm in our suspended core fibers. In order to qualify their nonlinearity we have pumped them at 1.995 μm with the help of a fibered ns source. We have observed a strong non linear response with evidence of spontaneous Raman scattering and strong spectral broadening.

  2. 51. DETAIL, VIEW OF CABLE SUSPENDED BRIDGE COUNTERWEIGHTS AND PULLEYS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. DETAIL, VIEW OF CABLE SUSPENDED BRIDGE COUNTERWEIGHTS AND PULLEYS FROM BRIDGE SUSPENSION STRUCTURE ON BRIDGE NO. 11. LOOKING WEST. - Greenville Yard, Transfer Bridge System, Port of New York/New Jersey, Upper New York Bay, Jersey City, Hudson County, NJ

  3. 5. An outboard view of a weight suspended over a ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. An outboard view of a weight suspended over a buoy tender's side through a chain stopper. - U.S. Coast Guard Buoy Tenders, 180' Class, U.S. Coast Guard Headquarters, 2100 Second Street Southwest, Washington, District of Columbia, DC

  4. Suspended Education Department Official Had Approved Waiver for Former Employer

    ERIC Educational Resources Information Center

    Basken, Paul

    2007-01-01

    Matteo Fontana, the student-aid official in the U.S. Department of Education who was suspended last month in an ethics case, issued a controversial high-stakes legal ruling in 2004 that benefited his former employer, Sallie Mae, on the day before the nation's top student lender completed its transition from a government-founded lender into a…

  5. 20. Photographic copy of photograph of roof suspender system taken ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Photographic copy of photograph of roof suspender system taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

  6. DEVELOPING WATER QUALITY CRITERIA FOR SUSPENDED AND BEDDED SEDIMENTS

    EPA Science Inventory

    The U.S. EPA’s Framework for Developing Suspended and Bedded Sediments (SABS) Water Quality Criteria (SABS Framework) is a nationally-consistent process for developing ambient sediment quality criteria for surface waters. The SABS Framework accommodates natural variation among wa...

  7. Vibrotactile evaluation: osseointegrated versus socket-suspended transfemoral prostheses.

    PubMed

    Häggström, Eva; Hagberg, Kerstin; Rydevik, Björn; Brånemark, Rickard

    2013-01-01

    This study investigated detection thresholds of vibrometric stimuli in patients with transfemoral amputation supplied with osseointegrated (OI) and socket-suspended prostheses. It included 17 patients tested preoperatively with socket-suspended prostheses and after 2 yr with OI prostheses and a control group (n = 17) using socket-suspended prostheses, evaluated once. Assessments on the prosthetic and intact feet were conducted at six frequencies (8, 16, 32, 64, 125, and 250 Hz). Furthermore, measurements were conducted to investigate how vibrometric signals are transmitted through a test prosthesis. The results showed that the OI group had improved ability to detect vibrations through the prosthesis at 125 Hz (p = 0.01) at follow-up compared with the preoperative measurement. Compared with the control group, the OI group at follow-up had better ability to detect high frequency vibrations through the prosthesis (125 Hz, p = 0.02; 250 Hz, p = 0.03). The vibrometric signal transmitted through the test prosthesis was reduced at 8, 125, and 250 Hz but was amplified at 16, 32, and 64 Hz. Differences between the OI and the control groups were found in the highest frequencies in which the test prosthesis showed reduction of the vibrometric signal. The study provides insight into the mechanisms of vibration transmission between the exterior and bone-anchored as well as socket-suspended amputation prostheses.

  8. Academic Success of Suspended Students. AIR 2001 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Howard, Richard D.; Borland, Ken; Johnson, Cel; Baker, Larry J.

    Cohorts of entering freshmen were tracked over time to determine whether the suspension policy at Montana State University (MSU), Bozeman was having the intended effect on academic success, defined as degree completion. The university's current policy requires students to be suspended after receiving grade point averages (GPAs) of lower than 2.00…

  9. 22. Detail view of sign suspended from portal strut (this ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Detail view of sign suspended from portal strut (this sign was located at the same place at both ends of Moody Bridge). Bottom: General elevation view to southeast showing northern abutment with solid rock foundation. - Moody Bridge, Spanning South Fork Eel River, Garberville, Humboldt County, CA

  10. Electrostatically suspended and sensed micro-mechanical rate gyroscope

    NASA Technical Reports Server (NTRS)

    Torti, R.; Gerver, M.; Gondhalekar, V.; Bart, S.; Maxwell, B.

    1994-01-01

    The goal of this work is development of fully electrostatically suspended and rebalancing angular rate sensing micro-gyroscope fabricated according to standard VLSI techniques. Fabrication of test structures is proceeding. Off chip electronics for the electrostatic sensing and driving circuits has been tested. The prototype device will be assembled in a hybrid construction including the FET input stages of the sensors.

  11. 40 CFR 230.21 - Suspended particulates/turbidity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Suspended particulates/turbidity. 230.21 Section 230.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING... time. These new levels may reduce light penetration and lower the rate of photosynthesis and...

  12. 40 CFR 230.21 - Suspended particulates/turbidity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Suspended particulates/turbidity. 230.21 Section 230.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING... time. These new levels may reduce light penetration and lower the rate of photosynthesis and...

  13. Effective Counseling Strategies for Supporting Long-Term Suspended Students

    ERIC Educational Resources Information Center

    Johnson, Janet L.; Sparks, Eric; Lewis, Rita G.; Niedrich, Kris; Hall, Mary; Johnson, Julie

    2006-01-01

    Long-term suspended (LTS) students are barred from the school system for lengthy periods, leaving them at risk of academic failure and vulnerable from lack of services. A program in a North Carolina public school system provided counselors to work with each LTS student. Outcome data were analyzed to determine the effectiveness of counseling…

  14. A Buoy for Continuous Monitoring of Suspended Sediment Dynamics

    PubMed Central

    Mueller, Philip; Thoss, Heiko; Kaempf, Lucas; Güntner, Andreas

    2013-01-01

    Knowledge of Suspended Sediments Dynamics (SSD) across spatial scales is relevant for several fields of hydrology, such as eco-hydrological processes, the operation of hydrotechnical facilities and research on varved lake sediments as geoarchives. Understanding the connectivity of sediment flux between source areas in a catchment and sink areas in lakes or reservoirs is of primary importance to these fields. Lacustrine sediments may serve as a valuable expansion of instrumental hydrological records for flood frequencies and magnitudes, but depositional processes and detrital layer formation in lakes are not yet fully understood. This study presents a novel buoy system designed to continuously measure suspended sediment concentration and relevant boundary conditions at a high spatial and temporal resolution in surface water bodies. The buoy sensors continuously record turbidity as an indirect measure of suspended sediment concentrations, water temperature and electrical conductivity at up to nine different water depths. Acoustic Doppler current meters and profilers measure current velocities along a vertical profile from the water surface to the lake bottom. Meteorological sensors capture the atmospheric boundary conditions as main drivers of lake dynamics. It is the high spatial resolution of multi-point turbidity measurements, the dual-sensor velocity measurements and the temporally synchronous recording of all sensors along the water column that sets the system apart from existing buoy systems. Buoy data collected during a 4-month field campaign in Lake Mondsee demonstrate the potential and effectiveness of the system in monitoring suspended sediment dynamics. Observations were related to stratification and mixing processes in the lake and increased turbidity close to a catchment outlet during flood events. The rugged buoy design assures continuous operation in terms of stability, energy management and sensor logging throughout the study period. We conclude that

  15. An analysis of bedload and suspended load interactions

    NASA Astrophysics Data System (ADS)

    Recking, alain; Navratil, Oldrich

    2013-04-01

    Several approaches were used to develop suspension equations. It includes semi-theoretical equations based on the convection diffusion equation (Einstein 1950; Van Rijn 1984; Camenen and Larson 2008; Julien 2010), semi-empirical tools based on energy concept (Velikanov 1954; Bagnold 1966), empirical adjustments (Prosser and Rusttomji 2000). One essential characteristic of all these equations is that most of them were developed by considering continuity between bedload and suspended load, and that the partitioning between these two modes of transport evolves progressively with increasing shear stress, which is the case for fine bed materials. The use of these equations is thus likely to be welcome in estuaries or lowland sandy rivers, but may be questionable in gravel-bed rivers and headwater streams where the bed is usually structured vertically and fine sediments potentially contributing to suspension are stored under a poorly mobile surface armour comprising coarse sediments. Thus one question this work aimed to answer is does the presence of an armour at the bed surface influence suspended load? This was investigated through a large field data set comprising instantaneous measurements of both bedload and suspension. We also considered the river characteristics, distinguishing between lowland rivers, gravel bed rivers and headwater streams. The results showed that a correlation exist between bedload and suspension for lowland and gravel bed rivers. This suggests that in gravel bed rivers a large part of the suspended load is fed by subsurface material, and depends on the remobilization of the surface material. No correlation was observed for head water streams where the sediment production is more likely related to hillslope processes. These results were used with a bedload transport equation for proposing a method for suspended load estimate. The method is rough, but especially for gravel bed rivers, it predicts suspended load reasonably well when compared to

  16. USING TURBIDITY DATA TO PREDICT SUSPENDED SEDIMENT CONCENTRATIONS: POSSIBILITIES, LIMITATIONS, AND PITFALLS

    EPA Science Inventory

    This talk will look at the relationships between turbidity and suspended sediment concentrations in a variety of geographic areas, geomorphic river types, and river sizes; and attempt to give guidance on using existing turbidity data to predict suspended sediment concentrations.

  17. Suspended single-walled carbon nanotube fluidic sensors

    NASA Astrophysics Data System (ADS)

    Son, B. H.; Park, Ji-Yong; Lee, Soonil; Ahn, Y. H.

    2015-09-01

    In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent with the ion depletion model. We also have measured conductance as a function of gate bias at different flow rates and have determined the flow-rate dependent effective charge density, which influences the electrostatic configuration around SWNT devices.In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent

  18. Turbidity - a Semi-Continuous Monitoring Option for Suspended Solids

    NASA Astrophysics Data System (ADS)

    Lendvay, J. M.; Rosasco, M. V.; David, K. E.

    2012-12-01

    Redwood Creek, a third order coastal stream flowing through Muir Woods National Monument and Golden Gate National Recreation Area in Marin County, California, was once the spawning grounds for a relatively large population of Coho Salmon (Oncorhynchus kisutch). In recent years less than 1% of historic populations have been returning to the stream. Redwood creek is currently undergoing extensive ecological restoration in an attempt to improve the spawning habitat for the salmon. The original stream path has been altered in the past to make way for development and the National Park Service has been working towards restoring much of the stream's natural functionality with the hope that the salmon population will increase. The restoration process has altered the surrounding riparian landscape in the Redwood Creek watershed. Riparian disturbance caused by vegetation and levee removal as a part of the restoration process followed by installation of seedlings raises concern about the concentration of sediments in the water. Throughout 2011-2012 three parameters for water quality were monitored at Redwood Creek. Suspended sediment concentration (SSC) and total suspended solids (TSS) measurements to determine the concentration of suspended particles in the water column at a given point in time. Turbidity, measured in Nephelometric Turbidity Units (NTU) is a measure of the water's cloudiness caused by suspended particles. Turbidity measurements are favored as they provide a semi-automated monitoring option. Therefore, development of a relationship between turbidity and SSC and TSS is desired. Water samples were analyzed for TSS and SSC using the EPA standard methods, and Turbidity was measured using a Hach 2100Q portable turbidimeter. Additional semi-continuous monitoring of turbidity was completed in situ using Hydrolab DS5X datasondes (with self-cleaning turbidity sensor). The relationship between TSS, SSC and turbidity was determined using a linear regression model for

  19. 30 CFR 585.1014 - When will BOEM suspend an Alternate Use RUE?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 2 2012-07-01 2012-07-01 false When will BOEM suspend an Alternate Use RUE... Alternate Use Rue Administration § 585.1014 When will BOEM suspend an Alternate Use RUE? (a) BOEM may suspend an Alternate Use RUE if: (1) Necessary to comply with judicial decrees; (2) Continued...

  20. 30 CFR 285.1014 - When will MMS suspend an Alternate Use RUE?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 2 2011-07-01 2011-07-01 false When will MMS suspend an Alternate Use RUE? 285... Facilities Alternate Use Rue Administration § 285.1014 When will MMS suspend an Alternate Use RUE? (a) The MMS may suspend an Alternate Use RUE if: (1) Necessary to comply with judicial decrees; (2)...

  1. 30 CFR 585.1014 - When will BOEM suspend an Alternate Use RUE?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 2 2014-07-01 2014-07-01 false When will BOEM suspend an Alternate Use RUE... Alternate Use Rue Administration § 585.1014 When will BOEM suspend an Alternate Use RUE? (a) BOEM may suspend an Alternate Use RUE if: (1) Necessary to comply with judicial decrees; (2) Continued...

  2. 30 CFR 285.1014 - When will MMS suspend an Alternate Use RUE?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false When will MMS suspend an Alternate Use RUE? 285... Rue Administration § 285.1014 When will MMS suspend an Alternate Use RUE? (a) The MMS may suspend an Alternate Use RUE if: (1) Necessary to comply with judicial decrees; (2) Continued activities pursuant...

  3. 30 CFR 585.1014 - When will BOEM suspend an Alternate Use RUE?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false When will BOEM suspend an Alternate Use RUE... Alternate Use Rue Administration § 585.1014 When will BOEM suspend an Alternate Use RUE? (a) BOEM may suspend an Alternate Use RUE if: (1) Necessary to comply with judicial decrees; (2) Continued...

  4. 9 CFR 2.10 - Licensees whose licenses have been suspended or revoked.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Licensees whose licenses have been suspended or revoked. 2.10 Section 2.10 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... have been suspended or revoked. (a) Any person whose license has been suspended for any reason...

  5. 12 CFR 116.260 - May the OCC suspend processing of my application?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false May the OCC suspend processing of my... APPLICATION PROCESSING PROCEDURES OCC Review Standard Treatment § 116.260 May the OCC suspend processing of my application? (a) Suspension. The OCC may, at any time, indefinitely suspend processing of your application...

  6. Understanding hydrothermal transformation from Mn2O3 particles to Na0.55Mn2O4·1.5H2O nanosheets, nanobelts, and single crystalline ultra-long Na4Mn9O18 nanowires

    PubMed Central

    Park, Yohan; Woo Lee, Sung; Kim, Ki Hyeon; Min, Bong-Ki; Kumar Nayak, Arpan; Pradhan, Debabrata; Sohn, Youngku

    2015-01-01

    Manganese oxides are one of the most valuable materials for batteries, fuel cells and catalysis. Herein, we report the change in morphology and phase of as-synthesized Mn2O3 by inserting Na+ ions. In particular, Mn2O3 nanoparticles were first transformed to 2 nm thin Na0.55Mn2O4·1.5H2O nanosheets and nanobelts via hydrothermal exfoliation and Na cation intercalation, and finally to sub-mm ultra-long single crystalline Na4Mn9O18 nanowires. This paper reports the morphology and phase-dependent magnetic and catalytic (CO oxidation) properties of the as-synthesized nanostructured Na intercalated Mn-based materials. PMID:26667348

  7. Ultraclean suspended monolayer graphene achieved by in situ current annealing

    NASA Astrophysics Data System (ADS)

    Wang, Haidong; Zhang, Xing; Takamatsu, Hiroshi

    2017-01-01

    Ultraclean graphene is essential for studying its intrinsic transport properties or fabricating high-performance electronic devices. Unfortunately, the contamination on graphene is unavoidable after microelectromechanical system processing. Here, we report an in situ current-annealing method for achieving ultraclean suspended monolayer graphene. The charge mobility of cleaned graphene reached a surprising 3.8 × 105 cm2 V-1 s-1, one of the highest values ever reported. For the first time, the process of current annealing was recorded under a high-resolution electron scanning microscope. It was demonstrated that temperature was the only dominant factor of the current-annealing process. Meanwhile, the mobility of suspended graphene was found to be highly sensitive to structural defects. The mobility decreased by a factor of over 100 after ion irradiation on graphene. The results revealed the underlying mechanism of current annealing on graphene and provided an effective means of preparing ultraclean graphene membranes.

  8. Directional Movement of Droplets in Grooves: Suspended or Immersed?

    PubMed Central

    Xu, Wei; Lan, Zhong; Peng, Benli; Wen, Rongfu; Chen, Yansong; Ma, Xuehu

    2016-01-01

    The behavior of droplets trapped in geometric structures is essential to droplet manipulation applications such as for droplet transport. Here we show that directional droplet movement can be realized by a V-shaped groove with the movement direction controlled by adjusting the surface wettability of the groove inner wall and the cross sectional angle of the groove. Experiments and analyses show that a droplet in a superhydrophobic groove translates from the immersed state to the suspended state as the cross sectional angle of the groove decreases and the suspended droplet departs from the groove bottom as the droplet volume increases. We also demonstrate that this simple grooved structure can be used to separate a water-oil mixture and generate droplets with the desired sizes. The structural effect actuated droplet movements provide a controllable droplet transport method which can be used in a wide range of droplet manipulation applications. PMID:26743167

  9. Superior thermal conductivity in suspended bilayer hexagonal boron nitride

    PubMed Central

    Wang, Chengru; Guo, Jie; Dong, Lan; Aiyiti, Adili; Xu, Xiangfan; Li, Baowen

    2016-01-01

    We reported the basal-plane thermal conductivity in exfoliated bilayer hexagonal boron nitride h-BN that was measured using suspended prepatterned microstructures. The h-BN sample suitable for thermal measurements was fabricated by dry-transfer method, whose sample quality, due to less polymer residues on surfaces, is believed to be superior to that of PMMA-mediated samples. The measured room temperature thermal conductivity is around 484 Wm−1K−1(+141 Wm−1K−1/ −24 Wm−1K−1) which exceeds that in bulk h-BN, providing experimental observation of the thickness-dependent thermal conductivity in suspended few-layer h-BN. PMID:27142571

  10. Gate-voltage induced trions in suspended carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yoshida, Masahiro; Popert, Alexander; Kato, Yuichiro K.

    We observe trion emission from suspended carbon nanotubes where carriers are introduced electrostatically using field-effect transistor structures. The trion peak emerges below the E11 emission energy at gate voltages that coincide with the onset of bright exciton quenching. By investigating nanotubes with various chiralities, we verify that the energy separation between the bright exciton peak and the trion peak becomes smaller for larger diameter tubes. Trion binding energies that are significantly larger compared to surfactant-wrapped carbon nanotubes are obtained, and the difference is attributed to the reduced dielectric screening in suspended tubes. Work supported by JSPS (KAKENHI 24340066), the Canon Foundation, the Sasakawa Scientific Research Grant, and MEXT (Photon Frontier Network Program, Nanotechnology Platform). M.Y. is supported by ALPS.

  11. Planktivorous Fish Recognize Temporal Motion Patterns of Suspended Particles

    NASA Astrophysics Data System (ADS)

    Strickler, J. R.; Tsonis, A.

    2004-12-01

    Small planktivorous fish feed by selective captures of individual zooplankters. We realize that: 1) the predator, as well as the prey is suspended in the water column, which does not provide either with stable reference points; 2) the ambient flow field acts differently on the larger predators than on the much smaller prey; and 3) within the water column there are many suspended particles of lower nutritional value than the zooplankters represent. We investigated in the laboratory whether or not fish can distinguish between small targets moving with different swimming patterns, e.g. particles entrained passively in the ambient water flow versus entrained but actively swimming particles. We created in an aquarium computer-animated stimuli with motion patterns ranging from random to actual swimming motions of live animals. The results show that planktivorous fish can recognize temporal patterns in a visually homogeneous environment. Therefore, blue-water fish must process visual information similar to terrestrial animals processing auditory information.

  12. Directional Movement of Droplets in Grooves: Suspended or Immersed?

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Lan, Zhong; Peng, Benli; Wen, Rongfu; Chen, Yansong; Ma, Xuehu

    2016-01-01

    The behavior of droplets trapped in geometric structures is essential to droplet manipulation applications such as for droplet transport. Here we show that directional droplet movement can be realized by a V-shaped groove with the movement direction controlled by adjusting the surface wettability of the groove inner wall and the cross sectional angle of the groove. Experiments and analyses show that a droplet in a superhydrophobic groove translates from the immersed state to the suspended state as the cross sectional angle of the groove decreases and the suspended droplet departs from the groove bottom as the droplet volume increases. We also demonstrate that this simple grooved structure can be used to separate a water-oil mixture and generate droplets with the desired sizes. The structural effect actuated droplet movements provide a controllable droplet transport method which can be used in a wide range of droplet manipulation applications.

  13. Suspended sediment transport in an ephemeral stream following wildfire

    USGS Publications Warehouse

    Malmon, D.V.; Reneau, S.L.; Katzman, D.; Lavine, A.; Lyman, J.

    2007-01-01

    We examine the impacts of a stand-clearing wildfire on the characteristics and magnitude of suspended sediment transport in ephemeral streams draining the burn area. We report the results of a monitoring program that includes 2 years of data prior to the Cerro Grande fire in New Mexico, and 3 years of postfire data. Suspended sediment concentration (SSC) increased by about 2 orders of magnitude following the fire, and the proportion of silt and clay increased from 50% to 80%. For a given flow event, SSC is highest at the flood bore and decreases monotonically with time, a pattern evident in every flood sampled both before and after the fire. We propose that the accumulation of flow and wash load at the flow front is an inherent characteristic of ephemeral stream flows, due to amplified momentum losses at the flood bore. We present a new model for computing suspended sediment transport in ephemeral streams (in the presence or absence of wildfire) by relating SSC to the time following the arrival of the flood bore, rather than to instantaneous discharge. Using this model and a rainfall history, we estimate that in the 3 years following the fire, floods transported in suspension a mass equivalent to about 3 mm of landscape lowering across the burn area, 20% of this following a single rainstorm. We test the model by computing fine sediment delivery to a small reservoir in an adjacent watershed, where we have a detailed record of postfire sedimentation based on repeat surveys. Systematic discrepancies between modeled and measured sedimentation rates in the reservoir suggest rapid reductions in suspended sediment delivery in the first several years after the fire.

  14. Converting near-bottom OBS measurements into suspended sediment concentrations

    USGS Publications Warehouse

    Xu, J. P.

    1997-01-01

    A method of estimating the mass proportion of nonhomogeneous sediment constituents in suspension is presented. This method provides a more accurate conversion of OBS measurements (volts) to suspended sediment concentrations (grams per liter). Given a set of calibration coefficients of end-members, the method allows one to obtain the spatially and temporally varying in situ coefficients that are used in the conversion. Field and/or laboratory experiments are needed to verify the method.

  15. Magnetically suspended stacks for inertial energy storage flywheel

    NASA Technical Reports Server (NTRS)

    Anand, Davinder K.; Kirk, James A.; Iwaskiw, Peter

    1987-01-01

    A magnetically suspended flywheel stack based on a 'pancake' magnetic bearing stack is proposed for a 500 watt-hour energy storage system. Backup ball bearings in the system configuration both prevent damage to the system whenever there is a loss of magnetic suspension due to excessive outside disturbances, and insure that the fywheel stays within the linear control range. Design tools to investigate the performance of the control system and the magnetic circuits are also discussed.

  16. Prototype of a magnetically suspended flywheel energy storage system

    NASA Technical Reports Server (NTRS)

    Plant, David P.; Kirk, J. A.; Anand, D. K.

    1989-01-01

    The authors describe recent progress in the development of a 500-Wh magnetically suspended flywheel stack energy storage system. The design of the system and a critical study of the noncontacting displacement transducers and their placement in the stack system are discussed. The storage system has been designed and constructed and is currently undergoing experimental analysis. The results acquired from the noncontacting displacement transducer study show that currently available transducers will not function as desired and that further research is essential.

  17. Suspended core photonic microcells for sensing and device applications.

    PubMed

    Wang, Chao; Jin, Wei; Ma, Jun; Wang, Ying; Ho, Hoi Lut; Shi, Xin

    2013-06-01

    In-line fiber-optic microcells are fabricated by postprocessing NKT LMA10 photonic crystal fibers. The cells are suspended core (SC) elements created by locally inflating some of the air holes while the core is being tapered. Based on a SC microcell with six air holes, a cantilever beam accelerometer is demonstrated. The microcells could also be used as gain and absorption cells for amplifier and spectroscopy applications.

  18. [Light absorption by suspended particulate matter in Chagan Lake, Jilin].

    PubMed

    Wang, Yuan-Dong; Liu, Dian-Wei; Song, Kai-Shan; Zhang, Bai; Wang, Zong-Ming; Jiang, Guang-Ji; Tang, Xu-Guang; Lei, Xiao-Chun; Wu, Yan-Qing

    2011-01-01

    Spectral characteristics and the magnitudes of light absorption by suspended particulate matter were determined by spectrophotometry in this optically complex Lake Chagan waters for the purpose of surveying the natural variability of the absorption coefficients to parameterize the bio-optical models for converting satellite or in-situ water reflectance signatures into water quality information. Experiments were carried out on seasonal frozen Lake Chagan, one representative inland case-2 water body in Northeast of China. Particulate absorption properties analyzed using the field data on July 15th and October 12th 2009 were measured using the quantitative filter technique to produce absorption spectra containing several fractions that could be attributed to two main optical active constituents (OACs) phytoplankton pigments and non-algal particulates (mineral sediments, and organic detritus). Results suggested that the suspended particulate matter (SPM) concentration was higher while phytoplankton biomass (chlorophyll-a concentration) was lower in July and that in October. The spectral shape of total suspended particulate matter resembled that of non-algal particulates which contributed greater than phytoplankton in total particulate absorption during both periods. An obvious absorption peak occurring at around 440 nm exhibited an increase in phytoplankton contribution in October. Non-algal particulate absorption at 440 nm (a(NAP) (440)) had better correlation with total suspended particulate matter concentration than that with chlorophyll-a over the two periods. Light absorption by phytoplankton pigments in the Chagan lake region was generally lower than that of non-algal components. Chl. a dominating phytoplankton pigment composition functioned exponentially with its absorption coefficients at 440 and 675 nm specifically, the average values of which in July were 0.146 8 m2 x mg(-1) and 0.050 3 respectively while in October they were 0.153 3 and 0.013 2 m2 x mg(-1

  19. Pyrethroid sorption to Sacramento River suspended solids and bed sediments

    PubMed Central

    Fojut, Tessa L.; Young, Thomas M.

    2011-01-01

    Sorption of pyrethroid insecticides to solid materials will typically dominate the fate and transport of these hydrophobic compounds in aquatic environments. Batch reactor isotherm experiments were performed with bifenthrin and λ-cyhalothrin with suspended material and bed sediment collected from the Sacramento River, CA. These batch reactor experiments were performed with low spiking concentrations and a long equilibration time (28 d) to be more relevant to environmental conditions. Sorption to suspended material and bed sediment was compared to examine the role of differential sorption between these phases in the environmental transport of pyrethroids. The equilibrium sorption data were fit to the Freundlich isotherm model and fit with r2 > 0.87 for all experiments. Freundlich exponents ranged from 0.72 ± 0.19 to 1.07 ± 0.050, indicating sorption nonlinearity for some of the experimental conditions and linearity for others over the concentration range tested. The Freundlich capacity factors were larger for the suspended solids than for the bed sediments and the suspended material had a higher specific surface area and higher organic carbon content compared to the bed sediment. Calculated organic carbon-normalized distribution coefficients were larger than those previously reported in the literature by approximately an order of magnitude and ranged from 106.16 to 106.68 at an equilibrium aqueous concentration of 0.1 µg/L. Higher than expected sorption of pyrethroids to the tested materials may be explained by sorption to black carbon and/or mineral surfaces. PMID:21191877

  20. Technological advances in suspended-sediment surrogate monitoring

    USGS Publications Warehouse

    Gray, John R.; Gartner, Jeffrey W.

    2009-01-01

    Surrogate technologies to continuously monitor suspended sediment show promise toward supplanting traditional data collection methods requiring routine collection and analysis of water samples. Commercially available instruments operating on bulk optic (turbidity), laser optic, pressure difference, and acoustic backscatter principles are evaluated based on cost, reliability, robustness, accuracy, sample volume, susceptibility to biological fouling, and suitable range of mass concentration and particle size distribution. In situ turbidimeters are widely used. They provide reliable data where the point measurements can be reliably correlated to the river's mean cross section concentration value, effects of biological fouling can be minimized, and concentrations remain below the sensor's upper measurement limit. In situ laser diffraction instruments have similar limitations and can cost 6 times the approximate $5000 purchase price of a turbidimeter. However, laser diffraction instruments provide volumetric-concentration data in 32 size classes. Pressure differential instruments measure mass density in a water column, thus integrating substantially more streamflow than a point measurement. They are designed for monitoring medium-to-large concentrations, are generally unaffected by biological fouling, and cost about the same as a turbidimeter. However, their performance has been marginal in field applications. Acoustic Doppler profilers use acoustic backscatter to measure suspended sediment concentrations in orders of magnitude more streamflow than do instruments that rely on point measurements. The technology is relatively robust and generally immune to effects of biological fouling. Cost of a single-frequency device is about double that of a turbidimeter. Multifrequency arrays also provide the potential to resolve concentrations by clay silt versus sand size fractions. Multifrequency hydroacoustics shows the most promise for revolutionizing collection of continuous

  1. Pseudomagnetic fields and ballistic transport in a suspended graphene sheet.

    PubMed

    Fogler, M M; Guinea, F; Katsnelson, M I

    2008-11-28

    We study a suspended graphene sheet subject to the electric field of a gate underneath. We compute the elastic deformation of the sheet and the corresponding effective gauge field, which modifies the electronic transport. In a clean system the two-terminal conductance of the sample is reduced below the ballistic limit and is almost totally suppressed at low carrier concentrations in samples under tension. Residual disorder restores a small finite conductivity.

  2. Magnetically suspended centrifugal blood pump with a self bearing motor.

    PubMed

    Masuzawa, Toru; Onuma, Hiroyuki; Kim, Seung-Jong; Okada, Yohji

    2002-01-01

    A magnetically suspended centrifugal blood pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semiopened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal blood pump is a candidate for an implantable left ventricular assist device.

  3. Raman spectroscopy of suspended mono and bilayer graphene

    NASA Astrophysics Data System (ADS)

    Kitt, Alexander; Feldman, Benjamin; Remi, Sebastian; Martin, Jens; Swan, Anna; Yacoby, Amir; Goldberg, Bennett

    2010-03-01

    Suspended mono and bilayer graphene flakes have been shown to have higher mobility and lower disorder than their supported counterparts^1. The geometry which decouples the flake from the substrate also causes an as yet uncharacterized backgate specific strain due to an electrostatic attraction between the graphene and the back gated substrate. We study this strain using spatially resolved Raman spectroscopy with a diffraction limited spot size. Upon application of uni-axial strain the unit cell is stretched reducing the symmetry of the system and breaking the double degeneracy of the G band causing a split in the peak. Additionally the Raman modes show a linear softening as a function of strain in the case of supported graphene. Suspended flakes provide an ideal system to study back gate tunable strain while avoiding complications due to substrates including the determination of the Poisson ratio and sample slippage^2. Here we present preliminary results of our observations. 1: B Feldman, J Martin, A Yacoby, ``Broken-symmetry states and divergent resistance in suspended bilayer graphene'', Nature Physics, doi:10.1038/nphys1406 2: C Metzger et al, ``Biaxial strain in graphene adhered to shallow depressions'', Accepted for publication in Nano Letters

  4. Method of making suspended thin-film semiconductor piezoelectric devices

    DOEpatents

    Casalnuovo, Stephen A.; Frye-Mason, Gregory C.

    2001-01-01

    A process for forming a very thin suspended layer of piezoelectric material of thickness less than 10 microns. The device is made from a combination of GaAs and AlGaAs layers to form either a sensor or an electronic filter. Onto a GaAs substrate is epitaxially deposited a thin (1-5 micron) sacrificial AlGaAs layer, followed by a thin GaAs top layer. In one embodiment the substrate is selectively etched away from below until the AlGaAs layer is reached. Then a second selective etch removes the sacrificial AlGaAs layer, that has acted here as an etch stop, leaving the thin suspended layer of piezoelectric GaAs. In another embodiment, a pattern of small openings is etched through the thin layer of GaAs on top of the device to expose the sacrificial AlGaAs layer. A second selective etch is done through these openings to remove the sacrificial AlGaAs layer, leaving the top GaAs layer suspended over the GaAs substrate. A novel etchant solution containing a surface tension reducing agent is utilized to remove the AlGaAs while preventing buildup of gas bubbles that would otherwise break the thin GaAs layer.

  5. Suspended single-walled carbon nanotube fluidic sensors.

    PubMed

    Son, B H; Park, Ji-Yong; Lee, Soonil; Ahn, Y H

    2015-10-07

    In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent with the ion depletion model. We also have measured conductance as a function of gate bias at different flow rates and have determined the flow-rate dependent effective charge density, which influences the electrostatic configuration around SWNT devices.

  6. Suspended sediment prolongs larval development in a coral reef fish.

    PubMed

    Wenger, Amelia S; McCormick, Mark I; Endo, Geoffrey G K; McLeod, Ian M; Kroon, Frederieke J; Jones, Geoffrey P

    2014-04-01

    Increasing sediment input into coastal environments is having a profound influence on shallow marine habitats and associated species. Coral reef ecosystems appear to be particularly sensitive, with increased sediment deposition and re-suspension being associated with declines in the abundance and diversity of coral reef fishes. While recent research has demonstrated that suspended sediment can have negative impacts on post-settlement coral reef fishes, its effect on larval development has not been investigated. In this study, we tested the effects of different levels of suspended sediment on larval growth and development time in Amphiprion percula, a coral reef damselfish. Larvae were subjected to four experimental concentrations of suspended sediment spanning the range found around coastal coral reefs (0-45 mg l(-1)). Larval duration was significantly longer in all sediment treatments (12 days) compared with the average larval duration in the control treatment (11 days). Approximately 75% of the fish in the control had settled by day 11, compared with only 40-46% among the sediment treatments. In the highest sediment treatment, some individuals had a larval duration twice that of the median duration in the control treatment. Unexpectedly, in the low sediment treatment, fish at settlement were significantly longer and heavier compared with fish in the other treatments, suggesting delayed development was independent of individual condition. A sediment-induced extension of the pelagic larval stage could significantly reduce numbers of larvae competent to settle and, in turn, have major effects on adult population dynamics.

  7. Estimation of suspended-sediment concentration from total suspended solids and turbidity data for Kentucky, 1978-1995

    USGS Publications Warehouse

    Williamson, Tanja N.; Crawford, Charles G.

    2011-01-01

    Suspended sediment is a constituent of water quality that is monitored because of concerns about accelerated erosion, nonpoint contamination of water resources, and degradation of aquatic environments. In order to quantify the relationship among different sediment parameters for Kentucky streams, long-term records were obtained from the National Water Information System of the U.S. Geological Survey. Suspended-sediment concentration (SSC), the parameter traditionally measured and reported by the U.S. Geological Survey, was statistically compared to turbidity and total suspended solids (TSS), two parameters that are considered surrogate data. A linear regression of log-transformed observations was used to estimate SSC from TSS; 72% of TSS observations were less than coincident SSC observations; however, the estimated SSC values were almost as likely to be overestimated as underestimated. The SSC-turbidity relationship also used log-transformed observations, but required a nonlinear, breakpoint regression that separated turbidity observations ???6nephelometric turbidity units. The slope for these low turbidity values was not significantly different than zero, indicating that low turbidity observations provide no real information about SSC; in the case of the Kentucky sediment record, this accounts for 30% of the turbidity observations. ?? 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA.

  8. A New Simple Suspended-Load Sampler: Continuous Particulate Matter Collection from Rivers with Low and High Suspended Matter Load

    NASA Astrophysics Data System (ADS)

    Kralik, Martin; Miesbauer, Hermann; Humer, Franko; Oberndorfer, Hermann

    2010-05-01

    Please fill in your abstract text. Suspended particulate matter (SPM) or suspended load in waters is the part of the stream load that is carried for a considerable period of time in suspension. Long term suspended sediment monitoring is hampered by the limited sample size or enormous investments in equipment and/or working hours. In addition many samplers are limited to easily accessible sampling points equipped with electric power supply or to certain types of streams and cannot operate unattended in case of floods. The sorption characteristics of the suspended particulate matter (wash load) have been recognized as important transporters of natural and anthropogenic trace constituents. To allow repeated analyses sometimes several grams of dried SPM are needed. All parts of the sediment sampler are available as spare parts in hardware stores and made of polyvinylchloride (PVC). The inlet device is connected with the sampler by a tubing of several meter length. Without a pump the sampler can be positioned at a safe place lower than the inlet device to allow a continuous flow. Only a small portion (0.001-0.002 l/s) of the river water flows down through the central pipe by gravitational force to the bottom of the container. Due to the considerable larger diameter of the container the water rises very slowly (1-3 hours) and leaves the container at a small overflow-pipe allowing a nearly complete settling and/or flocculation (80-90%) of the suspended load in the container. The sampler was tested in an alpine torrent and two rivers in flat areas. The newly developed sampler offers following advantages. The sampler (1) is inexpensive and robust, (2) operates in case of small cascade or cataracts (>0.5 m) without power supply, (3) can be used singly or in lateral or vertical nests, (4) allows continuous settling and flocculation without perturbation by vibrating movements of the sampler (5) is resistant to plugging and clogging by coarser particles and plant debris, (6

  9. Suspended Alexandrium spp. hypnozygote cysts in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Kirn, Sarah L.; Townsend, David W.; Pettigrew, Neal R.

    2005-09-01

    The life cycle of dinoflagellates of the genus Alexandrium includes sexual reproduction followed by the formation of a dormant hypnozygote cyst, which serves as a resting stage. Negatively buoyant cysts purportedly fall to the benthos where they undergo a mandatory period of quiescence. Previous reports of cysts in the surficial sediments of the Gulf of Maine, where Alexandrium blooms are well documented, show a broad distribution of cysts, with highest concentrations generally in sediments below 100 m depth. We report here an exploration of cysts suspended in the water column, where they would be better positioned to inoculate springtime Alexandrium populations. During cruises in February, April, and June of 2000, water samples were collected at depths just off the bottom (within 5 m), at the top of the bottom nepheloid layer, and near the surface (1 m) and examined for cyst concentrations. Suspended cysts were found throughout the Gulf of Maine and westernmost Bay of Fundy. Planktonic cyst densities were generally greater in near-bottom and top of the bottom nepheloid layer samples than in near-surface water samples; densities were of the order of 10 2 cysts m -3 in surface waters, and 10 2-10 3 cysts m -3 at near-bottom depths. Temporally, they were most abundant in February and least abundant in April. Reports by earlier workers of cysts in the underlying sediments were on the order of 10 3 cysts cm -3. We present calculations that demonstrate the likelihood of cyst resuspension from bottom sediments forced by swell and tidal currents, and propose that such resuspended cysts are important in inoculating the seasonal bloom. We estimate that suspended cysts may contribute significantly to the annual vegetative cell population in the Gulf of Maine.

  10. Super-bridges suspended over carbon nanotube cables

    NASA Astrophysics Data System (ADS)

    Carpinteri, Alberto; Pugno, Nicola M.

    2008-11-01

    In this paper the new concept of 'super-bridges', i.e. kilometre-long bridges suspended over carbon nanotube cables, is introduced. The analysis shows that the use of realistic (thus defective) carbon nanotube bundles as suspension cables can enlarge the current limit main span by a factor of ~3. Too large compliance and dynamic self-excited resonances could be avoided by additional strands, rendering the super-bridge anchored as a spider's cobweb. As an example, we have computed the limit main spans of the current existing 19 suspended-deck bridges longer than 1 km assuming them to have substituted their cables with carbon nanotube bundles (thus maintaining the same geometry, with the exception of the length) finding spans of up to ~6.3 km. We thus suggest that the design of the Messina bridge in Italy, which would require a main span of ~3.3 km, could benefit from the use of carbon nanotube bundles. We believe that their use represents a feasible and economically convenient solution. The plausibility of these affirmations is confirmed by a statistical analysis of the existing 100 longest suspended bridges, which follow a Zipf's law with an exponent of 1.1615: we have found a Moore-like (i.e. exponential) law, in which the doubling of the capacity (here the main span) per year is substituted by the factor 1.0138. Such a law predicts that the realization of the Messina bridge using conventional materials will only occur around the middle of the present century, whereas it could be expected in the near future if carbon nanotube bundles were used. A simple cost analysis concludes the paper.

  11. Closeup view of the Orbiter Discovery as it is suspended ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up view of the Orbiter Discovery as it is suspended vertically by the hoist in the transfer aisle of the Vehicle Assembly Building at Kennedy Space Center. This view is a detail of the starboard wing of the orbiter. Note the Reinforced Carbon-Carbon panels on the leading edge of the wing, the elevons and the elevon seal panels on the wing's trailing edge. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  12. Connecting source and transport: Suspended sediments in the Nepal Himalayas

    NASA Astrophysics Data System (ADS)

    Andermann, Christoff; Crave, Alain; Gloaguen, Richard; Davy, Philippe; Bonnet, Stéphane

    2012-10-01

    Understanding the dynamics of sediment fluxes is a key issue to constrain modern erosion rates in mountain belts and determine the still debated level of control exerted by precipitation, topography and tectonics. The well defined monsoon seasonality in the Himalayas, together with active tectonics and strong relief provide an ideal environment to assess these possible interactions. For this purpose, we present a new compilation of daily suspended sediment data for 12 stations of the major rivers of the Nepal Himalayas. We analyze the relationships of sediment transport with daily river discharge and precipitation data as well as with morphometric parameters. We show that suspended sediment concentrations vary systematically through the seasons and asynchronously to river discharge displaying a hysteresis effect. This clockwise hysteresis effect disappears when suspended sediment fluxes are directly compared with direct storm discharge. Therefore we attribute the hysteresis effect to groundwater dilution rather than a sediment supply limitation. We infer a rating model to calculate erosion rates directly from long river discharge chronicles. We show that, when normalized by drainage area and mean sediment flux, all rivers exhibit the same trend. This similarity implies that all river basins have the same erosion behavior, independent of location, size and catchment characteristics. Erosion rates calculated from suspended sediment fluxes range between 0.1 and 2.8 mm/yr. The erosion rates of the three main basins of Nepal are in the range 0.9-1.5 mm/yr, Erosion rates in the Higher Himalayas are relatively low (<0.5 mm/yr, except for Kali Gandaki), while in the Lesser Himalayas they range from 0.2 to 2 mm/yr. We propose that material transport in the rivers depends on hillslope sediment supply, which is, in turn, controlled by those rainfalls producing direct runoff. In other words, the rivers in the Nepal Himalayas are supply-limited and the hillsopes as a

  13. Photoacoustic response of suspended and hemolyzed red blood cells

    NASA Astrophysics Data System (ADS)

    Saha, Ratan K.; Karmakar, Subhajit; Roy, Madhusudan

    2013-07-01

    The effect of confinement of hemoglobin molecules on photoacoustic (PA) signal is studied experimentally. The PA amplitudes for samples with suspended red blood cells (SRBCs) and hemolyzed red blood cells (HRBCs) were found to be comparable at each hematocrit for 532 nm illumination. The difference between the corresponding amplitudes increased with increasing hematocrit for 1064 nm irradiation. For example, the PA amplitude for the SRBCs was about 260% higher than that of the HRBCs at 40% hematocrit. This observation may help to develop a PA method detecting hemolysis noninvasively.

  14. Regional volume changes in canine lungs suspended in air

    NASA Technical Reports Server (NTRS)

    Abbrecht, Peter H.; Kyle, Richard R.; Bryant, Howard J.; Feuerstein, Irwin

    1995-01-01

    The purpose of this study was to determine the effect of the absence of a pleural pressure gradient (simulating the presumed condition found in microgravity) upon regional expansion of the lung. We attempted to produce a uniform pressure over the surface of the lung by suspending excised lungs in air. Such studies should help determine whether or not the absence of a pleural pressure gradient leads to uniform ventilation. A preparation in which there is no pleural pressure gradient should also be useful in studying non-gravitational effects on ventilation distribution.

  15. Suspended sediment control and water quality conservation through riparian vegetation:

    NASA Astrophysics Data System (ADS)

    Pavanelli, D.; Cavazza, C.; Correggiari, S.

    2009-04-01

    Soil erosion and Suspended Sediment River are strongly related in the Apennines catchments which are generally characterised by a clayey lithology and impermeable soils and extensive and severe erosion and slope stability problems. In fact the suspended sediment yield represents one of the most reliable tools to assess real basin soil loss (Pavanelli and Pagliarani, 2002; Pavanelli and Rigotti, 2007) from the surface rain erosive features in a mountain watershed, as rills and interrills erosion, gullies, bad-lands (calanchi basins). Suspended sediment yield is known to imply several detrimental consequences: soil losses from agricultural land, worsening of the quality of the water, clogging of water supply filters and reservoir siltation. In addition, suspended sediment yield is also one of the main vector for pollutants and nutrients: various studies have already proved how nitrogen content has been constantly rising in aquifers and surface waters [Böhlke and Denver, 1995]. Finer particles and their aggregates have been proved to be the preferential vehicle for particulate nitrogen [Droppo et al., 1997; Ongley et al., 1992]. In one research [Pavanelli and al. 2006] four Apennines torrents (Gaiana, Sillaro, Savena and Lavino) with mountain basins ranging from 8.7 to 139 Km2 were monitored via automatic sampling devices, the samples of water collected were analysed to characterise suspended solids in terms of their grain size distribution and total nitrogen with respect to the source of eroded area in the catchment. Preliminary results [Pavanelli and al. 2007] seem to show the existence of a direct relationship between nitrogen concentration and finer particle concentration (<20 μm), with the maximum nitrogen loss values being related to factors like the presence of clayey formations, their position within the catchment and the availability of suspended particles. The results seem to indicate hillsides as main sources of suspended sediment to the torrents

  16. Characterizing the kinetics of suspended cylindrical particles by polarization measurements

    NASA Astrophysics Data System (ADS)

    Liao, Ran; Ou, Xueheng; Ma, Hui

    2015-09-01

    Polarization has promising potential to retrieve the information of the steady samples, such as tissues. However, for the fast changing sample such as the suspended algae in the water, the kinetics of the particles also influence the scattered polarization. The present paper will show our recent results to extract the information about the kinetics of the suspended cylindrical particles by polarization measurements. The sample is the aqueous suspension of the glass fibers stirred by a magnetic stirrer. We measure the scattered polarization of the fibers by use of a simultaneous polarization measurement system and obtain the time series of two orthogonal polarization components. By use of correlation analysis, we obtain the time parameters from the auto-correlation functions of the polarization components, and observe the changes with the stirring speeds. Results show that these time parameters indicate the immigration of the fibers. After discussion, we find that they may further characterize the kinetics, including the translation and rotation, of the glass fibers in the fluid field.

  17. Elastic properties of suspended multilayer WSe{sub 2}

    SciTech Connect

    Zhang, Rui Cheung, Rebecca; Koutsos, Vasileios

    2016-01-25

    We report the experimental determination of the elastic properties of suspended multilayer WSe{sub 2}, a promising two-dimensional (2D) semiconducting material combined with high optical quality. The suspended WSe{sub 2} membranes have been fabricated by mechanical exfoliation of bulk WSe{sub 2} and transfer of the exfoliated multilayer WSe{sub 2} flakes onto SiO{sub 2}/Si substrates pre-patterned with hole arrays. Then, indentation experiments have been performed on these membranes with an atomic force microscope. The results show that the 2D elastic modulus of the multilayer WSe{sub 2} membranes increases linearly while the prestress decreases linearly as the number of layers increases. The interlayer interaction in WSe{sub 2} has been observed to be strong enough to prevent the interlayer sliding during the indentation experiments. The Young's modulus of multilayer WSe{sub 2} (167.3 ± 6.7 GPa) is statistically independent of the thickness of the membranes, whose value is about two thirds of other most investigated 2D semiconducting transition metal dichalcogenides, namely, MoS{sub 2} and WS{sub 2}. Moreover, the multilayer WSe{sub 2} can endure ∼12.4 GPa stress and ∼7.3% strain without fracture or mechanical degradation. The 2D WSe{sub 2} can be an attractive semiconducting material for application in flexible optoelectronic devices and nano-electromechanical systems.

  18. Electrooptical behaviour and control of a suspended particle device

    NASA Astrophysics Data System (ADS)

    Vergaz, R.; Pena, J. M. S.; Barrios, D.; Pérez, I.; Torres, J. C.

    2007-09-01

    A suspended particle device is made by electrophoretic rod-shape particles suspended in an organic gel. These particles can twist and order with an applied voltage. The light crossing the material suffers more or less scattering according to that voltage. A commercial device is analyzed in this work. Several electrical models are tested, being the best one a series configuration including a shunt double layer capacitance and a Warburg element. Main parameter errors are below 2%, showing the quality of this new electrical model for this kind of devices. A quick method to improve the manufacturing process on-line is also proposed. Impedance measurements will be fitted to the selected electrical model, in order to check physical aspects such as charge diffusion lengths and response times. An electronic driver to obtain several levels of device transmission has been also developed, being its linearity demonstrated too. Colour changes are negligible for the main part of the bleaching process. All these features allow the use of this set in domotics application.

  19. Suspended sediment transport on the continental shelf near Davenport, California

    USGS Publications Warehouse

    Xu, J. P.; Noble, M.; Eittreim, S.L.

    2002-01-01

    Suspended sediment transport on the shelves off Santa Cruz and Davenport, California is studied using field measurements and bottom boundary layer modeling. Strong transport events mostly occur during storms in winter; the volume of winter sediment transport is at least one order of magnitude greater than that of summer/spring transport. Rock outcrops on the inner shelf (< 40 m of water) indicates an erosional environment, but an elongated mid-shelf mud deposit evidently suggests a depositional environment on the mid-shelf. The seafloor geology appears to correlate to the poleward and offshore sediment transport pattern. This study also suggests that suspended sediment moves out of Monterey Bay, roughly along the isobaths of the northern bay. This fine material, originally from river sources, and the material from the coastal cliff erosion that is subsequently introduced to the transport system through cross-shelf sediment transport, are believed to be the sources of the mid-shelf mud deposit. ?? 2002 Elsevier Science B.V. All rights reserved.

  20. Suspended animation-like state protects mice from lethal hypoxia.

    PubMed

    Blackstone, Eric; Roth, Mark B

    2007-04-01

    Joseph Priestley observed the high burn rate of candles in pure oxygen and wondered if people would "live out too fast" if we were in the same environment. We hypothesize that sulfide, a natural reducer of oxygen that is made in many cell types, acts as a buffer to prevent unrestricted oxygen consumption. To test this, we administered sulfide in the form of hydrogen sulfide (H2S) to mice (Mus musculus). As we have previously shown, H2S decreases the metabolic rate of mice by approximately 90% and induces a suspended animation-like state. Mice cannot survive for longer than 20 min when exposed to 5% oxygen. However, if mice are first put into a suspended animation-like state by a 20-min pretreatment with H2S and then are exposed to low oxygen, they can survive for more than 6.5 h in 5% oxygen with no apparent detrimental effects. In addition, if mice are exposed to a 20-min pretreatment with H2S followed by 1 h at 5% oxygen, they can then survive for several hours at oxygen tensions as low as 3%. We hypothesize that prior exposure to H2S reduces oxygen demand, therefore making it possible for the mice to survive with low oxygen supply. These results suggest that H2S may be useful to prevent damage associated with hypoxia.

  1. IUTAM symposium on hydrodynamic diffusion of suspended particles

    SciTech Connect

    Davis, R.H.

    1995-12-31

    Hydrodynamic diffusion refers to the fluctuating motion of nonBrownian particles (or droplets or bubbles) which occurs in a dispersion due to multiparticle interactions. For example, in a concentrated sheared suspension, particles do not move along streamlines but instead exhibit fluctuating motions as they tumble around each other. This leads to a net migration of particles down gradients in particle concentration and in shear rate, due to the higher frequency of encounters of a test particle with other particles on the side of the test particle which has higher concentration or shear rate. As another example, suspended particles subject to sedimentation, centrifugation, or fluidization, do not generally move relative to the fluid with a constant velocity, but instead experience diffusion-like fluctuations in velocity due to interactions with neighboring particles and the resulting variation in the microstructure or configuration of the suspended particles. In flowing granular materials, the particles interact through direct collisions or contacts (rather than through the surrounding fluid); these collisions also cause the particles to undergo fluctuating motions characteristic of diffusion processes. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  2. Controlled ripple texturing of suspended graphene and ultrathin graphite membranes.

    PubMed

    Bao, Wenzhong; Miao, Feng; Chen, Zhen; Zhang, Hang; Jang, Wanyoung; Dames, Chris; Lau, Chun Ning

    2009-09-01

    Graphene is nature's thinnest elastic material and displays exceptional mechanical and electronic properties. Ripples are an intrinsic feature of graphene sheets and are expected to strongly influence electronic properties by inducing effective magnetic fields and changing local potentials. The ability to control ripple structure in graphene could allow device design based on local strain and selective bandgap engineering. Here, we report the first direct observation and controlled creation of one- and two-dimensional periodic ripples in suspended graphene sheets, using both spontaneously and thermally generated strains. We are able to control ripple orientation, wavelength and amplitude by controlling boundary conditions and making use of graphene's negative thermal expansion coefficient (TEC), which we measure to be much larger than that of graphite. These results elucidate the ripple formation process, which can be understood in terms of classical thin-film elasticity theory. This should lead to an improved understanding of suspended graphene devices, a controlled engineering of thermal stress in large-scale graphene electronics, and a systematic investigation of the effect of ripples on the electronic properties of graphene.

  3. Thermoelectric unipolar spin battery in a suspended carbon nanotube.

    PubMed

    Cao, Zhan; Fang, Tie-Feng; He, Wan-Xiu; Luo, Hong-Gang

    2017-04-26

    A quantum dot formed in a suspended carbon nanotube exposed to an external magnetic field is predicted to act as a thermoelectric unipolar spin battery which generates pure spin current. The built-in spin flip mechanism is a consequence of the spin-vibration interaction resulting from the interplay between the intrinsic spin-orbit coupling and the vibrational modes of the suspended carbon nanotube. On the other hand, utilizing thermoelectric effect, the temperature difference between the electron and the thermal bath to which the vibrational modes are coupled provides the driving force. We find that both magnitude and direction of the generated pure spin current are dependent on the strength of spin-vibration interaction, the sublevel configuration in dot, the temperatures of electron and thermal bath, and the tunneling rate between the dot and the pole. Moreover, in the linear response regime, the kinetic coefficient is non-monotonic in the temperature T and it reaches its maximum when [Formula: see text] is about one phonon energy. The existence of a strong intradot Coulomb interaction is irrelevant for our spin battery, provided that high-order cotunneling processes are suppressed.

  4. Photoacoustic study on the possible components of total suspended particles

    NASA Astrophysics Data System (ADS)

    Wang, Xidong; Huang, Zuohua; Tang, Zhilie

    2006-02-01

    Total suspended particles (TSP) are one of the main atmospheric pollutants. The ingredients are very complex, mainly including black carbon (C),organic compound, inorganic compound and biologic component, which will do great harm to human's health. During environmental monitoring, the airborne suspended particle always is an index for evaluating the quality of atmosphere. In this article, possible mixture of TSP is proposed to determine its ingredients and content by photoacoustic spectroscopy. The normalized photoacoustic (PA) signal of the sulfur powder, mixtures of sulfur and black carbon in different proportions are obtained respectively. Simulation with linear equation says that the PA signal has a certain relationship with the content of sample. The normalized PA spectroscopy of various materials is acquired via examining the sample of the powder of cupric sulfate mixed with nitro compound (2, 5 -methoxybenzoic-4nitro-dehyde), Portland cement, residual particles of automobile exhaust pipe, ash of power plant's stocks. The experimental results have important reference value to the practical analysis of TSP, it also provides new possible methodology to the environmental monitoring.

  5. Suspended crystalline films of protein hydrophobin I (HFBI).

    PubMed

    Oude Vrielink, Anneloes S; Bomans, Paul H H; Vredenbregt, Edgar J D; Wirix, Maarten J M; Sommerdijk, Nico A J M; Luiten, O J; Voets, Ilja K

    2015-06-01

    Protein interfaces play an essential role in both natural and man-made materials as stabilizers, sensors, catalysts, and selective channels for ions and small molecules. Probing the molecular arrangement within such interfaces is of prime importance to understand the relation between structure and functionality. Here we report on the preparation and characterization of large area suspended crystalline films of class II hydrophobin HFBI. This small, amphiphilic globular protein readily self-assembles at the air-water interface into a 2D hexagonal lattice which can be transferred onto a holey carbon electron microscopy grid yielding large areas of hundreds of square micrometers intact hydrophobin film spun across micron-sized holes. Fourier transform analysis of low-dose electron microscopy images and selected area electron diffraction profiles reveal a unit cell dimension a=5.6±0.1nm, in agreement with reported atomic force microscopy studies on solid substrates and grazing incidence X-ray scattering experiments at the air-water interface. These findings constitute the first step towards the utilization of large-area suspended crystalline hydrophobin films as membranes for ultrapurification and chiral separation or as biological substrates for ultrafast electron diffraction.

  6. Thermoelectric unipolar spin battery in a suspended carbon nanotube

    NASA Astrophysics Data System (ADS)

    Cao, Zhan; Fang, Tie-Feng; He, Wan-Xiu; Luo, Hong-Gang

    2017-04-01

    A quantum dot formed in a suspended carbon nanotube exposed to an external magnetic field is predicted to act as a thermoelectric unipolar spin battery which generates pure spin current. The built-in spin flip mechanism is a consequence of the spin-vibration interaction resulting from the interplay between the intrinsic spin–orbit coupling and the vibrational modes of the suspended carbon nanotube. On the other hand, utilizing thermoelectric effect, the temperature difference between the electron and the thermal bath to which the vibrational modes are coupled provides the driving force. We find that both magnitude and direction of the generated pure spin current are dependent on the strength of spin-vibration interaction, the sublevel configuration in dot, the temperatures of electron and thermal bath, and the tunneling rate between the dot and the pole. Moreover, in the linear response regime, the kinetic coefficient is non-monotonic in the temperature T and it reaches its maximum when {{k}\\text{B}}T is about one phonon energy. The existence of a strong intradot Coulomb interaction is irrelevant for our spin battery, provided that high-order cotunneling processes are suppressed.

  7. A passively suspended Tesla pump left ventricular assist device.

    PubMed

    Izraelev, Valentin; Weiss, William J; Fritz, Bryan; Newswanger, Raymond K; Paterson, Eric G; Snyder, Alan; Medvitz, Richard B; Cysyk, Joshua; Pae, Walter E; Hicks, Dennis; Lukic, Branka; Rosenberg, Gerson

    2009-01-01

    The design and initial test results of a new passively suspended Tesla type left ventricular assist device blood pump are described. Computational fluid dynamics (CFD) analysis was used in the design of the pump. Overall size of the prototype device is 50 mm in diameter and 75 mm in length. The pump rotor has a density lower than that of blood and when spinning inside the stator in blood it creates a buoyant centering force that suspends the rotor in the radial direction. The axial magnetic force between the rotor and stator restrain the rotor in the axial direction. The pump is capable of pumping up to 10 L/min at a 70 mm Hg head rise at 8,000 revolutions per minute (RPM). The pump has demonstrated a normalized index of hemolysis level below 0.02 mg/dL for flows between 2 and 9.7 L/min. An inlet pressure sensor has also been incorporated into the inlet cannula wall and will be used for control purposes. One initial in vivo study showed an encouraging result. Further CFD modeling refinements are planned and endurance testing of the device.

  8. Magnetically suspended stepping motors for clean room and vacuum environments

    NASA Technical Reports Server (NTRS)

    Higuchi, Toshiro

    1994-01-01

    To answer the growing needs for super-clean or contact free actuators for uses in clean rooms, vacuum chambers, and space, innovative actuators which combine the functions of stepping motors and magnetic bearings in one body were developed. The rotor of the magnetically suspended stepping motor is suspended like a magnetic bearing and rotated and positioned like a stepping motor. The important trait of the motor is that it is not a simple mixture or combination of a stepping motor and conventional magnetic bearing, but an amalgam of a stepping motor and a magnetic bearing. Owing to optimal design and feed-back control, a toothed stator and rotor are all that are needed structurewise for stable suspension. More than ten types of motors such as linear type, high accuracy rotary type, two-dimensional type, and high vacuum type were built and tested. This paper describes the structure and design of these motors and their performance for such applications as precise positioning rotary table, linear conveyor system, and theta-zeta positioner for clean room and high vacuum use.

  9. IUTAM symposium on hydrodynamic diffusion of suspended particles

    NASA Technical Reports Server (NTRS)

    Davis, R. H. (Editor)

    1995-01-01

    Hydrodynamic diffusion refers to the fluctuating motion of nonBrownian particles (or droplets or bubbles) which occurs in a dispersion due to multiparticle interactions. For example, in a concentrated sheared suspension, particles do not move along streamlines but instead exhibit fluctuating motions as they tumble around each other. This leads to a net migration of particles down gradients in particle concentration and in shear rate, due to the higher frequency of encounters of a test particle with other particles on the side of the test particle which has higher concentration or shear rate. As another example, suspended particles subject to sedimentation, centrifugation, or fluidization, do not generally move relative to the fluid with a constant velocity, but instead experience diffusion-like fluctuations in velocity due to interactions with neighboring particles and the resulting variation in the microstructure or configuration of the suspended particles. In flowing granular materials, the particles interact through direct collisions or contacts (rather than through the surrounding fluid); these collisions also cause the particles to undergo fluctuating motions characteristic of diffusion processes. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  10. A Passively-Suspended Tesla Pump Left Ventricular Assist Device

    PubMed Central

    Izraelev, Valentin; Weiss, William J.; Fritz, Bryan; Newswanger, Raymond K.; Paterson, Eric G.; Snyder, Alan; Medvitz, Richard B.; Cysyk, Joshua; Pae, Walter E.; Hicks, Dennis; Lukic, Branka; Rosenberg, Gerson

    2009-01-01

    The design and initial test results of a new passively suspended Tesla type LAVD blood pump are described. CFD analysis was used in the design of the pump. Overall size of the prototype device is 50 mm in diameter and 75 mm in length. The pump rotor has a density lower than that of blood and when spinning inside the stator in blood it creates a buoyant centering force that suspends the rotor in the radial direction. The axial magnetic force between the rotor and stator restrain the rotor in the axial direction. The pump is capable of pumping up to 10 liters/min at a 70 mmHg head rise at 8000 RPM. The pump has demonstrated a normalized index of hemolysis level below .02 mg/dL for flows between 2 and 9.7 L/min. An inlet pressure sensor has also been incorporated into the inlet cannula wall and will be used for control purposes. One initial in vivo study showed an encouraging result. Further CFD modeling refinements are planned as well as endurance testing of the device. PMID:19770799

  11. Structure and Dynamics of Freely Suspended Liquid Crystals

    NASA Technical Reports Server (NTRS)

    Clark, Noel A.

    2004-01-01

    Smectic liquid crystals are phases of rod shaped molecules organized into one dimensionally (1 D) periodic arrays of layers, each layer being between one and two molecular lengths thick. In the least ordered smectic phases, the smectics A and C, each layer is a two dimensional (2D) liquid. Additionally there are a variety of more ordered smectic phases having hexatic short range translational order or 2D crystalline or quasi long range translational order within the layers. The inherent fluid-layer structure and low vapor pressure of smectic liquid crystals enables the long term stabilization of freely suspended, single component, layered fluid films as thin as 30A, a single molecular layer. The layering forces the films to be an integral number of smectic layers thick, quantizing their thickness in layer units and forcing a film of a particular number of layers to be physically homogeneous with respect to its layer structure over its entire area. Optical reflectivity enables the precise determination of the number of layers. These ultrathin freely suspended liquid crystal films are structures of fundamental interest in condensed matter and fluid physics. They are the thinnest known stable fluid structures and have the largest surface-to-volume ratio of any stable fluid preparation, making them ideal for the study of the effects of reduced dimensionality on phase behavior and on fluctuation and interface phenomena. Their low vapor pressure and quantized thickness enable the effective use of microgravity to extend the study of basic capillary phenomena to ultrathin fluid films. Freely suspended films have been a wellspring of new LC physics. They have been used to provide unique experimental conditions for the study of condensed phase transitions in two dimensions. They are the only system in which the hexatic has been unambiguously identified as a phase of matter, and the only physical system in which fluctuations of a 2D XY system and Kosterlitz Thouless phase

  12. Development of an Integrated Suspended Sediment Sampling System - Prototype Results

    NASA Astrophysics Data System (ADS)

    Nerantzaki, Sofia; Moirogiorgou, Konstantia; Efstathiou, Dionissis; Giannakis, George; Voutsadaki, Stella; Zervakis, Michalis; Sibetheros, Ioannis A.; Zacharias, Ierotheos; Karatzas, George P.; Nikolaidis, Nikolaos P.

    2015-04-01

    The Mediterranean region is characterized by a unique micro-climate and a complex geologic and geomorphologic environment caused by its position in the Alpine orogenesis belt. Unique features of the region are the temporary rivers that are dry streams or streams with very low flow for most of the time over decadal time scales. One of their key characteristics is that they present flashy hydrographs with response times ranging from minutes to hours. It is crucial to monitor flash-flood events and observe their behavior since they can cause environmental degradation of the river's wider location area. The majority of sediment load is transferred during these flash events. Quantification of these fluxes through the development of new measuring devices is of outmost importance as it is the first step for a comprehensive understanding of the water quality, the soil erosion and erosion sources, and the sediment and nutrient transport routes. This work proposes an integrated suspended sediment sampling system which is implemented in a complex semi-arid Mediterranean watershed (i.e. the Koiliaris River Basin of Crete) with temporary flow tributaries and karstic springs. The system consists of sensors monitoring water stage and turbidity, an automated suspended sediment sampler, and an online camera recording video sequence of the river flow. Water stage and turbidity are continuously monitored and stage is converted to flow with the use of a rating curve; when either of these variables exceeds certain thresholds, the pump of the sediment sampler initiates sampling with a rotation proportional to the stage (flow weighted sampling). The water passes through a filter that captures the sediment, the solids are weighted after each storm and the data are converted to a total sediment flux. At the same time, the online camera derives optical measurements for the determination of the two-dimensional river flow velocity and the spatial sediment distribution by analyzing the Hue

  13. Summary of suspended-sediment concentration data, San Francisco Bay, California, water year 2008

    USGS Publications Warehouse

    Buchanan, Paul A.; Morgan, Tara L.

    2011-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2008 (October 1, 2007–September 30, 2008). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2007 through September 2008. Calibration curves and plots of the processed data for each sensor also are presented.

  14. Summary of Suspended-Sediment Concentration Data, San Francisco Bay, California, Water Year 2007

    USGS Publications Warehouse

    Buchanan, Paul A.; Morgan, Tara L.

    2010-01-01

    Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2007 (October 1, 2006-September 30, 2007). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments.Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2006 through September 2007. Calibration curves and plots of the processed data for each sensor also are presented.

  15. Electrochemical sensor having suspended element counter electrode and deflection method for current sensing

    DOEpatents

    Thundat, Thomas G.; Brown, Gilbert M.

    2010-05-18

    An electrochemical suspended element-based sensor system includes a solution cell for holding an electrolyte comprising solution including at least one electrochemically reducible or oxidizable species. A working electrode (WE), reference electrode (RE) and a counter electrode (CE) are disposed in the solution. The CE includes an asymmetric suspended element, wherein one side of the suspended element includes a metal or a highly doped semiconductor surface. The suspended element bends when current associated with reduction or oxidation of the electrochemically reducible or oxidizable species at the WE passes through the suspended element. At least one measurement system measures the bending of the suspended element or a parameter which is a function of the bending.

  16. An instrument system for monitoring and sampling suspended sediment in the benthic boundary layer

    USGS Publications Warehouse

    Sternberg, R.W.; Johnson, R.V.; Cacchione, D.A.; Drake, D.E.

    1986-01-01

    An instrument system has been constructed that can monitor and sample suspended sediment distributions in the benthic boundary layer. It consists of miniature nephelometers and suspended sediment samplers placed within one meter of the seabed. The system is capable of continuously monitoring suspended sediment profiles at eight levels between 14 and 100 cm above the seabed and collecting suspended sediment samples at four levels (20, 50, 70 and 100 cm) at three times during a deployment period. The suspended sediment system is designed to fit onto the instrumented tripod GEOPROBE which contains four electromagnetic current meters, pressure sensor, bottom stereo camera, two temperature sensors, transmissometer, and a Savonius rotor current meter. Sensor operation, data recording, and sediment sampling events are synchronized. Thus detailed measurements of the near-bottom flow conditions are made concurrently with suspended sediment measurements. The combined system has been used in sediment transporting environments within San Francisco Bay, California, and Puget Sound, Washington. ?? 1986.

  17. Suspended Planar-Array Chips for Molecular Multiplexing at the Microscale.

    PubMed

    Torras, Núria; Agusil, Juan Pablo; Vázquez, Patricia; Duch, Marta; Hernández-Pinto, Alberto M; Samitier, Josep; de la Rosa, Enrique J; Esteve, Jaume; Suárez, Teresa; Pérez-García, Lluïsa; Plaza, José A

    2016-02-17

    A novel suspended planar-array chips technology is described, which effectively allows molecular multiplexing using a single suspended chip to analyze extraordinarily small volumes. The suspended chips are fabricated by combining silicon-based technology and polymer-pen lithography, obtaining increased molecular pattern flexibility, and improving miniaturization and parallel production. The chip miniaturization is so dramatic that it permits the intracellular analysis of living cells.

  18. Laboratory requirements for in-situ and remote sensing of suspended material

    NASA Technical Reports Server (NTRS)

    Kuo, C. Y.; Cheng, R. Y. K.

    1978-01-01

    Recommendations for laboratory and in-situ measurements required for remote sensing of suspended material are presented. This study investigates the properties of the suspended materials, factors influencing the upwelling radiance, and the various types of remote sensing techniques. Calibration and correlation procedures are given to obtain the accuracy necessary to quantify the suspended materials by remote sensing. In addition, the report presents a survey of the national need for sediment data, the agencies that deal with and require the data of suspended sediment, and a summary of some recent findings of sediment measurements.

  19. Laboratory requirements for in-situ and remote sensing of suspended material

    NASA Technical Reports Server (NTRS)

    Kuo, C. Y.; Cheng, R. Y. K.

    1976-01-01

    Recommendations for laboratory and in-situ measurements required for remote sensing of suspended material are presented. This study investigates the properties of the suspended materials, factors influencing the upwelling radiance, and the various types of remote sensing techniques. Calibration and correlation procedures are given to obtain the accuracy necessary to quantify the suspended materials by remote sensing. In addition, the report presents a survey of the national need for sediment data, the agencies that deal with and require the data of suspended sediment, and a summary of some recent findings of sediment measurements.

  20. Influence of suspended solids on acute toxicity of carbofuran to Daphnia magna: I. Interactive effects.

    PubMed

    Herbrandson, Carl; Bradbury, Steven P; Swackhamer, Deborah L

    2003-05-29

    This study explored the effects on Daphnia magna from exposure to the pesticide carbofuran in combination with stress from suspended solids exposure. Our objective was to assess whether suspended solids affects the toxicodynamic response of D. magna to carbofuran. A series of laboratory experiments was performed where animals were exposed to carbofuran concentrations ranging from 0 to 160 microg/l in combination with suspended solids concentrations ranging from 0 to 10000 mg/l. In the absence of suspended solids, effects of carbofuran were dose dependent and resulted in an EC(50) of 92 microg/l. Exposure to suspended solids, up to extreme levels that may be encountered in the environment and in the absence of carbofuran, showed no measurable toxicity. When D. magna were exposed to a constant carbofuran concentration, the numbers of affected organisms increased with increasing suspended solids concentrations. At a suspended solids concentration of 1000 mg/l, the EC(50) for carbofuran was reduced by half to 45 microg/l. The relationship between the toxicity of carbofuran (microg/l) and the concentration of suspended solids (mg/l) can be described with the following equation: carbofuran EC(50)=72 exp(-0.00014 [suspended solids]). An analysis of the data indicates that this relationship is consistent with a potentiated toxicity mechanism rather than an additive model.

  1. 40 CFR 1068.440 - How do I ask EPA to reinstate my suspended certificate?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) AIR POLLUTION CONTROLS GENERAL COMPLIANCE PROVISIONS FOR ENGINE PROGRAMS Selective Enforcement... asking us to reinstate your suspended certificate. In your report, identify the reason for the...

  2. Remote sensing of suspended sediment water research: principles, methods, and progress

    NASA Astrophysics Data System (ADS)

    Shen, Ping; Zhang, Jing

    2011-12-01

    In this paper, we reviewed the principle, data, methods and steps in suspended sediment research by using remote sensing, summed up some representative models and methods, and analyzes the deficiencies of existing methods. Combined with the recent progress of remote sensing theory and application in water suspended sediment research, we introduced in some data processing methods such as atmospheric correction method, adjacent effect correction, and some intelligence algorithms such as neural networks, genetic algorithms, support vector machines into the suspended sediment inversion research, combined with other geographic information, based on Bayesian theory, we improved the suspended sediment inversion precision, and aim to give references to the related researchers.

  3. TiO{sub 2} nanobelts with a uniform coating of g-C{sub 3}N{sub 4} as a highly effective heterostructure for enhanced photocatalytic activities

    SciTech Connect

    Zhong, Xing; Jin, Meimei; Dong, Huaqing; Liu, Lin; Wang, Lei; Yu, Huiyou; Leng, Shuai; Zhuang, Guilin; Li, Xiaonian; Wang, Jian-guo

    2014-12-15

    A novel g-C{sub 3}N{sub 4}/TiO{sub 2} nanobelt (NB) heterostructure was successfully designed and prepared. The as-prepared g-C{sub 3}N{sub 4}/TiO{sub 2} NB heterostructure exhibited high photocatalytic activity not only in the photodegradation of Rhodamine B (RhB) but also in photocatalytic H{sub 2} production. The g-C{sub 3}N{sub 4}/TiO{sub 2} NB heterostructure with a mass ratio of 1:1 demonstrated the best performance in the photodegradation of RhB, whereas a mass ratio of 3:1 demonstrated the highest H{sub 2} production rate of 46.6 μmol h{sup −1} in photocatalytic H{sub 2} production. We conclude that the synergistic effect between g-C{sub 3}N{sub 4} and TiO{sub 2} NBs promotes the photogenerated carrier separation in space. This valuable insight into the rational architectural design of nanostructure-based photocatalysts is expected to shed light on other photocatalytic reaction systems in the future. - Graphical abstract: A novel strategy to fabricate the g-C{sub 3}N{sub 4}/TiO{sub 2} nanobelt (NB) heterostructures was reported. The g-C{sub 3}N{sub 4}/TiO{sub 2} NB heterostructures exhibited highly effective photocatalytic activities for photodegradation of Rhodamine B and H{sub 2} production. - Highlights: • A novel strategy to fabricate the g-C{sub 3}N{sub 4}/TiO{sub 2} NB heterostructures was reported. • The heterostructure exhibited high catalytic activity in photodegradation of RhB. • The heterostructure showed good H{sub 2} productivity in photocatalytic water splitting. • The synergistic effect between g-C{sub 3}N{sub 4} and TiO{sub 2} NBs are important. • This study shows that the heterostructure can be an effective photocatalyst.

  4. An overview of suspended sediment sampling in Hungary

    NASA Astrophysics Data System (ADS)

    Tamás, E. A.; Goda, L.

    2009-04-01

    Suspended sediment is being monitored in Hungary for over half a century now. Time to time different types of analyses had been carried out on the data series of certain gauging stations, but the results always showed rather high variability, big std deviation and inhomogeneity of the - otherwise relatively long -data series. In the past few years, with new river regulation and navigation development initiatives, and with the need for accurate information and data on the sediment transport of the Danube which could serve as input for modeling, our attention turned to the measurement tools, timing and techniques, which, according to our hypothesis, are few of the most important factors that can be accounted for the high variability in the quality of the datasets available.

  5. River suspended sediment modelling using a fuzzy logic approach

    NASA Astrophysics Data System (ADS)

    Kisi, Ozgur; Emin Karahan, M.; En, Zekai

    2006-12-01

    Correct estimation of sediment volume carried by a river is very important for many water resources projects. Conventional sediment rating curves, however, are not able to provide sufficiently accurate results. In this paper, a fuzzy logic approach is proposed to estimate suspended sediment concentration from streamflow. This study provides forecasting benchmarks for sediment concentration prediction in the form of a numerical and graphical comparison between fuzzy and rating-curve models. Benchmarking was based on a 5-year period of continuous streamflow and sediment concentration data of Quebrada Blanca Station operated by the United States Geological Survey. The benchmark results showed that the fuzzy model was able to produce much better results than rating-curve models. The fuzzy model proposed in the study is site specific and does not simulate the hysteresis effects. Copyright

  6. Shaping inputs to reduce vibration for suspended payloads

    SciTech Connect

    Noakes, M.W.; Jansen, J.F.

    1990-01-01

    The purpose of this paper is to show how to reduce the vibrational motion of an object transported by an overhead crane. Recent work at Sandia National Laboratories (SNL) has shown that oscillation-damped transport and swing-free stops are possible by properly programming the acceleration of the transporting crane. The main objective of this paper is to generalize the theory associated with oscillation-damped trajectories for simply suspended objects based on the work at Massachusetts Institute of Technology (MIT). Further, the results are applied to a full-scale implementation of the damped oscillation methods for the Oak Ridge National Laboratory's (ORNL) Advanced Integrated Maintenance System (AIMS). Hardware and software requirements and constraints for proper operation are discussed. Finally, test results and lessons learned'' are presented. 4 refs., 6 figs.

  7. Nanopores in suspended WS2 membranes for DNA sequencing

    NASA Astrophysics Data System (ADS)

    Danda, Gopinath; Masih Das, Paul; Chou, Yung-Chien; Mlack, Jerome; Naylor, Carl; Perea-Lopez, Nestor; Lin, Zhong; Fulton, Laura Beth; Terrones, Mauricio; Johnson, A. T. Charlie; Drndic, Marija

    Recent advances in solid-state nanopore sensor systems for DNA detection and analysis have been supported by using increasingly thinner materials to the point of utilizing atomically thin two-dimensional materials such as graphene and MoS2. However, these materials still have issues with pore wettability and signal-to-noise ratios displayed in DNA translocation measurements. Recently, the fabrication and operation of nanopores in MoS2 have been demonstrated, but the wetting properties and signal-to-noise ratios of transition metal dichalcogenides are yet to be understood and further improved. Here we fabricate suspended WS2 nanopore devices with sub-10 nm pore diameters using a novel nanomaterial transfer method and TEM nanosculpting to study and better understand nanopore wetting properties and performance in DNA translocation measurements.

  8. Identifying dominant sources of respirable suspended particulates in Guangzhou, China

    SciTech Connect

    Song, Y.; Dai, W.; Wang, X.S.; Cui, M.M.; Su, H.; Xie, S.D.; Zhang, Y.H.

    2008-09-15

    Respirable suspended particulates (RSP, i.e., particles with an aerodynamic diameter of 10 {mu} m or less) were measured in 2004 and 2005 at seven sites in the rapidly developing Guangzhou area of China. The average RSP concentration was 126 {mu} g m{sup -3}, a high level that could be very harmful to human health. The chemical species composition of the RSP, including organic and elemental carbon, water-soluble ions, and elemental compositions, was also analyzed. The organics and sulfate may be the major components of RSP mass concentrations. Positive matrix factorization (PMF) was used to identify the sources of RSP as secondary sulfates (32%), secondary nitrates (6%), biomass burning (15%), coal fly ash/cement (18%), sea salt (3%), crustal dust (5%), vehicle exhaust (6%), and coal-fired power plants (3%). Reducing coal combustion and controlling vehicle emissions would alleviate RSP pollution, as most of the precursors were components of coal burning emissions and vehicular exhaust.

  9. Suspended Patch Antenna Array With Electromagnetically Coupled Inverted Microstrip Feed

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2000-01-01

    The paper demonstrates a four-element suspended patch antenna array, with a parasitic patch layer and an electromagnetically coupled inverted microstrip feed, for linear polarization at K-Band frequencies. This antenna has the following advantages over conventional microstrip antennas: First, the inverted microstrip has lower attenuation than conventional microstrip; hence, conductor loss associated with the antenna corporate feed is lower resulting in higher gain and efficiency. Second, conventional proximity coupled patch antennas require a substrate for the feed and a superstrate for the patch. However, the inverted microstrip fed patch antenna makes use of a single substrate, and hence, is lightweight and low cost. Third, electromagnetic coupling results in wider bandwidth. Details regarding the design and fabrication will be presented as well as measured results including return loss, radiation patterns and cross-polarization levels.

  10. Suspended-sediment concentration regimes in Tennessee biological reference streams

    USGS Publications Warehouse

    Diehl, Timothy H.; Wolfe, William J.

    2010-01-01

    Suspended-sediment-concentration (SSC) regimes of five biological reference streams in Tennessee were characterized from 15-minute SSC records spanning 1 to 4 water years (October 1 through September 30) between 2004 and 2008. These streams represent least disturbed conditions for their respective ecoregions and have exceptional biodiversity in terms of fish or aquatic invertebrates. SSC regimes in streams, when plotted in terms of duration above a given SSC at a given annual frequency such as the annual maximum or the annual tenth longest duration, can be compared directly to published biological impairment thresholds derived from experimental trials. Based on such comparison, the SSC regimes of all five reference streams reached published impairment thresholds at least 10 times per water year for all years of record. The results suggest that the published impairment thresholds are not directly applicable to streams in Tennessee and, by extension, the southeastern United States.

  11. Final prototype of magnetically suspended flywheel energy storage system

    NASA Technical Reports Server (NTRS)

    Anand, D. K.; Kirk, J. A.; Zmood, R. B.; Pang, D.; Lashley, C.

    1991-01-01

    A prototype of a 500 Wh magnetically suspended flywheel energy storage system was designed, built, and tested. The authors present the work done and include the following: (1) a final design of the magnetic bearing, control system, and motor/generator, (2) construction of a prototype system consisting of the magnetic bearing stack, flywheel, motor, container, and display module, and (3) experimental results for the magnetic bearings, motor, and the entire system. The successful completion of the prototype system has achieved: (1) manufacture of tight tolerance bearings, (2) stability and spin above the first critical frequency, (3) use of inside sensors to eliminate runout problems, and (4) integration of the motor and magnetic bearings.

  12. Integration of suspended carbon nanotubes into micro-fabricated devices

    NASA Astrophysics Data System (ADS)

    Karp, Gabriel A.; Ya'akobovitz, Assaf; David-Pur, Moshe; Ioffe, Zvi; Cheshnovsky, Ori; Krylov, Slava; Hanein, Yael

    2009-08-01

    The integration of suspended carbon nanotubes into micron-scale silicon-based devices offers many exciting advantages in the realm of nano-scale sensing and micro- and nano-electromechanical systems (MEMS and NEMS). To realize such devices, simple fabrication schemes are needed. Here we present a new method to integrate carbon nanotubes into silicon-based devices by applying conventional micro-fabrication methods combined with a guided chemical vapor deposition growth of single-wall carbon nanotubes. The described procedure yields clean, long, taut and well-positioned tubes in electrical contact to conducting electrodes. The positioning, alignment and tautness of the tubes are all controlled by the structural and chemical features of the micro-fabricated substrate. As the approach described consists of common micro-fabrication and chemical vapor deposition growth procedures, it offers a viable route toward MEMS-NEMS integration and commercial utilization of carbon nanotubes as nano-electromechanical transducers.

  13. Dynamics and yielding of binary self-suspended nanoparticle fluids.

    PubMed

    Agrawal, Akanksha; Yu, Hsiu-Yu; Srivastava, Samanvaya; Choudhury, Snehashis; Narayanan, Suresh; Archer, Lynden A

    2015-07-14

    Yielding and flow transitions in bi-disperse suspensions of particles are studied using a model system comprised of self-suspended spherical nanoparticles. An important feature of the materials is that the nanoparticles are uniformly dispersed in the absence of a solvent. Addition of larger particles to a suspension of smaller ones is found to soften the suspensions, and in the limit of large size disparities, completely fluidizes the material. We show that these behaviors coincide with a speeding-up of de-correlation dynamics of all particles in the suspensions and are accompanied by a reduction in the energy dissipated at the yielding transition. We discuss our findings in terms of ligand-mediated jamming and un-jamming of hairy particle suspensions.

  14. Dynamics of suspended sediment plumes in Lake Ontario

    NASA Technical Reports Server (NTRS)

    Pluhowski, E. J. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Enhancement of ERTS-1 imagery yielded excellent quality 35-mm color slides and prints of several prominent turbidity plumes in Lake Ontario. Selected ERTS-1 frames of the Welland Canal and Genesee River plumes will be used to develop time-lapse sequences showing the impact of wind stress on each plume. Unusually high lake levels during the spring resulted in extensive beach erosion along the entire Lake Ontario shoreline. The resulting high concentrations of suspended matter generated highly turbid (up to 420 JTU) nearshore conditions that appeared milky white in the imagery obtained April 12 and 29th, 1973. During the shipping season, both the Welland Canal and a diversion channel at Port Dalhousie, Ontario, produced readily identifiable turbidity plumes in Lake Ontario. However, in the winter neither plume was visible in the ERTS-1 imagery suggesting sharply lower sediment discharge into Lake Ontario from these sources.

  15. A suspended dive-net technique for catching territorial divers

    USGS Publications Warehouse

    Uher-Koch, Brian D.; Rizzolo, Daniel; Wright, Kenneth G.; Schmutz, Joel A.

    2016-01-01

    A variety of methods such as night-lighting and lift nets have been used to catch divers (Gavidae), although 24-hour daylight in the Arctic summer and the remote nature of field sites can make the use of these traditional methods impossible. Our research required capture of adult divers at remote locations in northern Alaska. Here we describe a suspended dive-net technique that we used to safely capture territorial White-billed Gavia adamsii and Pacific Divers G. pacifica and that is lightweight and easy to set up. We also were able to capture divers with chicks, and failed breeders, and suggest that this method could be used to catch other territorial aquatic diving birds, especially other diver species.

  16. Propulsion simulation for magnetically suspended wind tunnel models

    NASA Technical Reports Server (NTRS)

    Joshi, Prakash B.; Beerman, Henry P.; Chen, James; Krech, Robert H.; Lintz, Andrew L.; Rosen, David I.

    1990-01-01

    The feasibility of simulating propulsion-induced aerodynamic effects on scaled aircraft models in wind tunnels employing Magnetic Suspension and Balance Systems. The investigation concerned itself with techniques of generating exhaust jets of appropriate characteristics. The objectives were to: (1) define thrust and mass flow requirements of jets; (2) evaluate techniques for generating propulsive gas within volume limitations imposed by magnetically-suspended models; (3) conduct simple diagnostic experiments for techniques involving new concepts; and (4) recommend experiments for demonstration of propulsion simulation techniques. Various techniques of generating exhaust jets of appropriate characteristics were evaluated on scaled aircraft models in wind tunnels with MSBS. Four concepts of remotely-operated propulsion simulators were examined. Three conceptual designs involving innovative adaptation of convenient technologies (compressed gas cylinders, liquid, and solid propellants) were developed. The fourth innovative concept, namely, the laser-assisted thruster, which can potentially simulate both inlet and exhaust flows, was found to require very high power levels for small thrust levels.

  17. Two-dimensional microrheology of freely suspended liquid crystal films.

    PubMed

    Eremin, A; Baumgarten, S; Harth, K; Stannarius, R; Nguyen, Z H; Goldfain, A; Park, C S; Maclennan, J E; Glaser, M A; Clark, N A

    2011-12-23

    Smectic liquid crystals form freely-suspended, fluid films of highly uniform structure and thickness, making them ideal systems for studies of hydrodynamics in two dimensions. We have measured particle mobility and shear viscosity by direct observation of the gravitational drift of silica spheres and smectic islands included in these fluid membranes. In thick films, we observe a hydrodynamic regime dominated by lateral confinement effects, with the mobility of the inclusion determined predominantly by coupling of the fluid flow to the fixed boundaries of the film. In thin films, the mobility of inclusions is governed primarily by coupling of the fluid to the surrounding air, as predicted by Saffman-Delbrück theory.

  18. Force fluctuations in three-dimensional suspended fibroblasts.

    PubMed

    Schlosser, Florian; Rehfeldt, Florian; Schmidt, Christoph F

    2015-02-05

    Cells are sensitive to mechanical cues from their environment and at the same time generate and transmit forces to their surroundings. To test quantitatively forces generated by cells not attached to a substrate, we used a dual optical trap to suspend 3T3 fibroblasts between two fibronectin-coated beads. In this simple geometry, we measured both the cells' elastic properties and the force fluctuations they generate with high bandwidth. Cell stiffness decreased substantially with both myosin inhibition by blebbistatin and serum-starvation, but not with microtubule depolymerization by nocodazole. We show that cortical forces generated by non-muscle myosin II deform the cell from its rounded shape in the frequency regime from 0.1 to 10 Hz. The amplitudes of these forces were strongly reduced by blebbistatin and serum starvation, but were unaffected by depolymerization of microtubules. Force fluctuations show a spectrum that is characteristic for an elastic network activated by random sustained stresses with abrupt transitions.

  19. Evaluation of Technologies to Remove Suspended Solids from Waste Water

    SciTech Connect

    Poirier, M.R.

    1999-03-15

    The Effluent Treatment Facility (ETF) at the Savannah River Site utilizes pH adjustment, submicron filtration, Hg removal resin, activated carbon, reverse osmosis, cationic exchange, and evaporation to remove contaminants from radioactive waste water. After startup, the ETF had difficulty achieving design capacity. The primary problem was fouling of the ceramic microfilters. Typical filter flow rates were only 20 percent of design capacity.A research program was conducted to identify and evaluate technologies for improving suspended solids removal from radioactive wastewater at the Savannah River Site. Technolgies investigated were a ceramic microfilter, a tubular polymeric ultrafilter, two porous metal filters, a polymeric centrifugal ultrafilter, a deep bed filter, a backwashable cartridge filter, a fabric filter, and a centriguge.

  20. 33. VIEW OF FOUR OF SEVEN MONITORS SUSPENDED FROM CEILING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. VIEW OF FOUR OF SEVEN MONITORS SUSPENDED FROM CEILING OF SLC-3W CONTROL ROOM NEAR NORTH WALL. LEFT TO RIGHT ABOVE THE MONITORS: DIGITAL GREENWICH MEAN TIME CLOCK, COMPLEX SAFETY WARNING LIGHTS FOR SLC-3W (PAD-2) AND LOB (THE GREEN LIGHT ON THE BOTTOM OF EACH STACK IS ILLUMINATED), AND DIGITAL COUNTDOWN AND HOLD CLOCKS. LEFT TO RIGHT BELOW THE MONITORS: INDICATOR LIGHTS SHOWING WHICH PAD OR VEHICLE FACILITIES ARE RECEIVING POWER FROM POWER PLANT 4 ON SOUTH VAFB, LIGHTS TO INDICATE IF POWER PLANT 4 IS ON OR OFF LINE, DIGITAL COUNTDOWN CLOCK, AND MILITARY-TIME CLOCK. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA