Strong coupling of plasmon and nanocavity modes for dual-band, near-perfect absorbers and ultrathin photovoltaics

DOE PAGES

Hagglund, Carl; Zeltzer, Gabriel; Ruiz, Ricardo; ...

2016-01-29

In this study, when optical resonances interact strongly, hybridized modes are formed with mixed properties inherited from the basic modes. Strong coupling therefore tends to equalize properties such as damping and oscillator strength of the spectrally separate resonance modes. This effect is here shown to be very useful for the realization of near-perfect dual-band absorption with ultrathin (~10 nm) layers in a simple geometry. Absorber layers are constructed by atomic layer deposition of the heavy-damping semiconductor tin monosulfide (SnS) onto a two-dimensional gold nanodot array. In combination with a thin (55 nm) SiO 2 spacer layer and a highly reflectivemore » Al film on the back, a semiopen nanocavity is formed. The SnS-coated array supports a localized surface plasmon resonance in the vicinity of the lowest order antisymmetric Fabry–Perot resonance of the nanocavity. Very strong coupling of the two resonances is evident through anticrossing behavior with a minimum peak splitting of 400 meV, amounting to 24% of the plasmon resonance energy. The mode equalization resulting from this strong interaction enables simultaneous optical impedance matching of the system at both resonances and thereby two near-perfect absorption peaks, which together cover a broad spectral range. When paired with the heavy damping from SnS band-to-band transitions, this further enables approximately 60% of normal incident solar photons with energies exceeding the band gap to be absorbed in the 10 nm SnS coating. Thereby, these results establish a distinct relevance of strong coupling phenomena to efficient, nanoscale photovoltaic absorbers and more generally for fulfilling a specific optical condition at multiple spectral positions.« less

Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets: Preparation and Application in Highly Sensitive and Selective DNA Detection.

PubMed

Peng, Yongwu; Huang, Ying; Zhu, Yihan; Chen, Bo; Wang, Liying; Lai, Zhuangchai; Zhang, Zhicheng; Zhao, Meiting; Tan, Chaoliang; Yang, Nailiang; Shao, Fangwei; Han, Yu; Zhang, Hua

2017-06-28

The ability to prepare ultrathin two-dimensional (2D) covalent organic framework (COF) nanosheets (NSs) in high yield is of great importance for the further exploration of their unique properties and potential applications. Herein, by elaborately designing and choosing two flexible molecules with C 3v molecular symmetry as building units, a novel imine-linked COF, namely, TPA-COF, with a hexagonal layered structure and sheet-like morphology, is synthesized. Since the flexible building units are integrated into the COF skeletons, the interlayer stacking becomes weak, resulting in the easy exfoliation of TPA-COF into ultrathin 2D NSs. Impressively, for the first time, the detailed structural information, i.e., the pore channels and individual building units in the NSs, is clearly visualized by using the recently developed low-dose imaging technique of transmission electron microscopy (TEM). As a proof-of-concept application, the obtained ultrathin COF NSs are used as a novel fluorescence sensing platform for the highly sensitive and selective detection of DNA.

High-mobility ultrathin semiconducting films prepared by spin coating.

PubMed

Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

2004-03-18

The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

High-mobility ultrathin semiconducting films prepared by spin coating

NASA Astrophysics Data System (ADS)

Mitzi, David B.; Kosbar, Laura L.; Murray, Conal E.; Copel, Matthew; Afzali, Ali

2004-03-01

The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (~50Å), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS2-xSex films, which exhibit n-type transport, large current densities (>105Acm-2) and mobilities greater than 10cm2V-1s-1-an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

Evidence for graphite-like hexagonal AlN nanosheets epitaxially grown on single crystal Ag(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsipas, P.; Kassavetis, S.; Tsoutsou, D.

Ultrathin (sub-monolayer to 12 monolayers) AlN nanosheets are grown epitaxially by plasma assisted molecular beam epitaxy on Ag(111) single crystals. Electron diffraction and scanning tunneling microscopy provide evidence that AlN on Ag adopts a graphite-like hexagonal structure with a larger lattice constant compared to bulk-like wurtzite AlN. This claim is further supported by ultraviolet photoelectron spectroscopy indicating a reduced energy bandgap as expected for hexagonal AlN.

Ultrathin Uniform Platinum Nanowires via a Facile Route Using an Inverse Hexagonal Surfactant Phase Template.

PubMed

Akbar, Samina; Boswell, Jacob; Worsley, Carys; Elliott, Joanne M; Squires, Adam M

2018-06-19

We present an attractive method for the fabrication of long, straight, highly crystalline, ultrathin platinum nanowires. The fabrication is simply achieved using an inverse hexagonal (H II ) lyotropic liquid crystal phase of the commercial surfactant phytantriol as a template. A platinum precursor dissolved within the cylindrical aqueous channels of the liquid crystal phase is chemically reduced by galvanic displacement using stainless steel. We demonstrate the production of nanowires using the H II phase in the phytantriol/water system which we obtain either by heating to 55 °C or at room temperature by the addition of a hydrophobic liquid, 9- cis-tricosene, to relieve packing frustration. The two sets of conditions produced high aspect nanowires with diameters of 2.5 and 1.7 nm, respectively, at least hundreds of nanometers in length, matching the size of the aqueous channels in which they grow. This versatile approach can be extended to produce highly uniform nanowires from a range of metals.

Green Fabrication of Ultrathin Co3O4 Nanosheets from Metal-Organic Framework for Robust High-Rate Supercapacitors.

PubMed

Xiao, Zhenyu; Fan, Lili; Xu, Ben; Zhang, Shanqing; Kang, Wenpei; Kang, Zixi; Lin, Huan; Liu, Xiuping; Zhang, Shiyu; Sun, Daofeng

2017-12-06

Two-dimensional cobalt oxide (Co 3 O 4 ) is a promising candidate for robust electrochemical capacitors with high performance. Herein, we use 2,3,5,6-tetramethyl-1,4-diisophthalate as a recyclable ligand to construct a Co-based metal-organic framework of UPC-9, and subsequently, we obtain ultrathin hierarchical Co 3 O 4 hexagonal nanosheets with a thickness of 3.5 nm through a hydrolysis and calcination process. A remarkable and excellent specific capacitance of 1121 F·g -1 at a current density of 1 A·g -1 and 873 F·g -1 at a current density of 25 A·g -1 were achieved for the as-prepared asymmetric supercapacitor, which can be attributed to the ultrathin 2D morphology and the rich macroporous and mesoporous structures of the ultrathin Co 3 O 4 nanosheets. This synthesis strategy is environmentally benign and economically viable due to the fact that the costly organic ligand molecules are recycled, reducing the materials cost as well as the environmental cost for the synthesis process.

Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Wensheng, E-mail: yws118@gmail.com; Gu, Min, E-mail: mgu@swin.edu.au; Tao, Zhikuo

2015-03-02

The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The J{sub sc} values are 12.1, 13.0, and 14.3 mA/cm{sup 2} and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high lightmore » trapping within amorphous silicon layer.« less

Ultrathin hexagonal MgO nanoflakes coated medical textiles and their enhanced antibacterial activity

NASA Astrophysics Data System (ADS)

Veeran Ponnuvelu, Dinesh; Selvaraj, Aravind; Prema Suriyaraj, Shanmugam; Selvakumar, Rajendran; Pulithadathail, Biji

2016-10-01

A facile hydrothermal method for development of ultrathin MgO nanoplates from different precursors and their enhanced antibacterial activity after coating onto medical textiles is reported. Ultrathin MgO nanoplates having hexagonal structure were characterized using UV-visible spectroscopy, atomic force microscopy, field emission scanning electron microscopy, x-ray diffraction and high resolution transmission electron microscopy. The formation of MgO nanoplates was found to exhibit profound anionic effect leading to ultrathin, planar structures with exposed MgO [111] facets, which may be responsible for enhanced antimicrobial activity. Medical fabrics (bleached 100% cotton) were coated with MgO nanoplates using pad-dry-cure method. The antibacterial activity of these fabrics was tested against Bacillus subtilis and Escherichia coli. The MgO nanoplates coated onto the fabric were found to have good adherence properties owing to their two-dimensional structure and were durable even after repeated washings without substantial reduction in the antimicrobial activity. The enhanced antibacterial activity may be attributed to the presence of oxygen vacancies, surface oxygen anions and hydroxyl groups on the surface of MgO nanoplates. This cost-effective functional finish (anti-microbial) to cotton fabric using MgO nanoplates may be suitable for many prospective medical applications and can serve as an alternative to the costlier silver based antimicrobial textiles.

Hot-Chemistry Structural Phase Transformation in Single-Crystal Chalcogenides for Long-Life Lithium Ion Batteries.

PubMed

Hassan, Fathy M; Hu, Qianqian; Fu, Jing; Batmaz, Rasim; Li, Jingde; Yu, Aiping; Xiao, Xingcheng; Chen, Zhongwei

2017-06-21

Tuned chalcogenide single crystals rooted in sulfur-doped graphene were prepared by high-temperature solution chemistry. We present a facile route to synthesize a rod-on-sheet-like nanohybrid as an active anode material and demonstrate its superior performance in lithium ion batteries (LIBs). This nanohybrid contains a nanoassembly of one-dimensional (1D) single-crystalline, orthorhombic SnS onto two-dimensional (2D) sulfur-doped graphene. The 1D nanoscaled SnS with the rodlike single-crystalline structure possesses improved transport properties compared to its 2D hexagonal platelike SnS 2 . Furthermore, we blend this hybrid chalcogenide with biodegradable polymer composite using water as a solvent. Upon drying, the electrodes were subjected to heating in vacuum at 150 °C to induce polymer condensation via formation of carboxylate groups to produce a mechanically robust anode. The LIB using the as-developed anode material can deliver a high volumetric capacity of ∼2350 mA h cm -3 and exhibit superior cycle stability over 1500 cycles as well as a high capacity retention of 85% at a 1 C rate. The excellent battery performance combined with the simplistic, scalable, and green chemistry approach renders this anode material as a very promising candidate for LIB applications.

Multidirection Piezoelectricity in Mono- and Multilayered Hexagonal α-In2Se3.

PubMed

Xue, Fei; Zhang, Junwei; Hu, Weijin; Hsu, Wei-Ting; Han, Ali; Leung, Siu-Fung; Huang, Jing-Kai; Wan, Yi; Liu, Shuhai; Zhang, Junli; He, Jr-Hau; Chang, Wen-Hao; Wang, Zhong Lin; Zhang, Xixiang; Li, Lain-Jong

2018-05-22

Piezoelectric materials have been widely used for sensors, actuators, electronics, and energy conversion. Two-dimensional (2D) ultrathin semiconductors, such as monolayer h-BN and MoS 2 with their atom-level geometry, are currently emerging as new and attractive members of the piezoelectric family. However, their piezoelectric polarization is commonly limited to the in-plane direction of odd-number ultrathin layers, largely restricting their application in integrated nanoelectromechanical systems. Recently, theoretical calculations have predicted the existence of out-of-plane and in-plane piezoelectricity in monolayer α-In 2 Se 3 . Here, we experimentally report the coexistence of out-of-plane and in-plane piezoelectricity in monolayer to bulk α-In 2 Se 3 , attributed to their noncentrosymmetry originating from the hexagonal stacking. Specifically, the corresponding d 33 piezoelectric coefficient of α-In 2 Se 3 increases from 0.34 pm/V (monolayer) to 5.6 pm/V (bulk) without any odd-even effect. In addition, we also demonstrate a type of α-In 2 Se 3 -based flexible piezoelectric nanogenerator as an energy-harvesting cell and electronic skin. The out-of-plane and in-plane piezoelectricity in α-In 2 Se 3 flakes offers an opportunity to enable both directional and nondirectional piezoelectric devices to be applicable for self-powered systems and adaptive and strain-tunable electronics/optoelectronics.

Polarization independent subtractive color printing based on ultrathin hexagonal nanodisk-nanohole hybrid structure arrays.

PubMed

Zhao, Jiancun; Yu, Xiaochang; Yang, Xiaoming; Xiang, Quan; Duan, Huigao; Yu, Yiting

2017-09-18

Structural color printing based on plasmonic metasurfaces has been recognized as a promising alternative to the conventional dye colorants, though the color brightness and polarization tolerance are still a great challenge for practical applications. In this work, we report a novel plasmonic metasurface for subtractive color printing employing the ultrathin hexagonal nanodisk-nanohole hybrid structure arrays. Through both the experimental and numerical investigations, the subtractive color thus generated taking advantages of extraordinary low transmission (ELT) exhibits high brightness, polarization independence and wide color tunability by varying key geometrical parameters. In addition, other regular patterns including square, pentagonal and circular shapes are also surveyed, and reveal a high color brightness, wide gamut and polarization independence as well. These results indicate that the demonstrated plasmonic metasurface has various potential applications in high-definition displays, high-density optical data storage, imaging and filtering technologies.

Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

NASA Astrophysics Data System (ADS)

Alam, M. T.; Bresnehan, M. S.; Robinson, J. A.; Haque, M. A.

2014-01-01

Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m-1 K-1, is lower than the bulk basal plane value (390 W m-1 K-1) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

Shape induced magnetic vortex state in hexagonal ordered cofe nanodot arrays using ultrathin alumina shadow mask

NASA Astrophysics Data System (ADS)

Sellarajan, B.; Saravanan, P.; Ghosh, S. K.; Nagaraja, H. S.; Barshilia, Harish C.; Chowdhury, P.

2018-04-01

The magnetization reversal process of hexagonal ordered CoFe nanodot arrays was investigated as a function of nanodot thickness (td) varying from 10 to 30 nm with fixed diameter. For this purpose, ordered CoFe nanodots with a diameter of 80 ± 4 nm were grown by sputtering using ultra-thin alumina mask. The vortex annihilation and the dynamic spin configuration in the ordered CoFe nanodots were analyzed by means of magnetic hysteresis loops in complement with the micromagnetic simulation studies. A highly pinched hysteresis loop observed at 20 nm thickness suggests the occurrence of vortex state in these nanodots. With increase in dot thickness from 10 to 30 nm, the estimated coercivity values tend to increase from 80 to 175 Oe, indicating irreversible change in the nucleation/annihilation field of vortex state. The measured magnetic properties were then corroborated with the change in the shape of the nanodots from disk to hemisphere through micromagnetic simulation.

Freestanding palladium nanosheets with plasmonic and catalytic properties

NASA Astrophysics Data System (ADS)

Huang, Xiaoqing; Tang, Shaoheng; Mu, Xiaoliang; Dai, Yan; Chen, Guangxu; Zhou, Zhiyou; Ruan, Fangxiong; Yang, Zhilin; Zheng, Nanfeng

2011-01-01

Ultrathin metal films can exhibit quantum size and surface effects that give rise to unique physical and chemical properties. Metal films containing just a few layers of atoms can be fabricated on substrates using deposition techniques, but the production of freestanding ultrathin structures remains a significant challenge. Here we report the facile synthesis of freestanding hexagonal palladium nanosheets that are less than 10 atomic layers thick, using carbon monoxide as a surface confining agent. The as-prepared nanosheets are blue in colour and exhibit a well-defined but tunable surface plasmon resonance peak in the near-infrared region. The combination of photothermal stability and biocompatibility makes palladium nanosheets promising candidates for photothermal therapy. The nanosheets also exhibit electrocatalytic activity for the oxidation of formic acid that is 2.5 times greater than that of commercial palladium black catalyst.

Microplasma Processed Ultrathin Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Thermal Transport Performance.

PubMed

Zhang, Ri-Chao; Sun, Dan; Lu, Ai; Askari, Sadegh; Macias-Montero, Manuel; Joseph, Paul; Dixon, Dorian; Ostrikov, Kostya; Maguire, Paul; Mariotti, Davide

2016-06-01

This Research Article reports on the enhancement of the thermal transport properties of nanocomposite materials containing hexagonal boron nitride in poly(vinyl alcohol) through room-temperature atmospheric pressure direct-current microplasma processing. Results show that the microplasma treatment leads to exfoliation of the hexagonal boron nitride in isopropyl alcohol, reducing the number of stacks from >30 to a few or single layers. The thermal diffusivity of the resulting nanocomposites reaches 8.5 mm(2) s(-1), 50 times greater than blank poly(vinyl alcohol) and twice that of nanocomposites containing nonplasma treated boron nitride nanosheets. From TEM analysis, we observe much less aggregation of the nanosheets after plasma processing along with indications of an amorphous carbon interfacial layer, which may contribute to stable dispersion of boron nitride nanosheets in the resulting plasma treated colloids.

Synergistically Enhanced Performance of Ultrathin Nanostructured Silicon Solar Cells Embedded in Plasmonically Assisted, Multispectral Luminescent Waveguides.

PubMed

Lee, Sung-Min; Dhar, Purnim; Chen, Huandong; Montenegro, Angelo; Liaw, Lauren; Kang, Dongseok; Gai, Boju; Benderskii, Alexander V; Yoon, Jongseung

2017-04-25

Ultrathin silicon solar cells fabricated by anisotropic wet chemical etching of single-crystalline wafer materials represent an attractive materials platform that could provide many advantages for realizing high-performance, low-cost photovoltaics. However, their intrinsically limited photovoltaic performance arising from insufficient absorption of low-energy photons demands careful design of light management to maximize the efficiency and preserve the cost-effectiveness of solar cells. Herein we present an integrated flexible solar module of ultrathin, nanostructured silicon solar cells capable of simultaneously exploiting spectral upconversion and downshifting in conjunction with multispectral luminescent waveguides and a nanostructured plasmonic reflector to compensate for their weak optical absorption and enhance their performance. The 8 μm-thick silicon solar cells incorporating a hexagonally periodic nanostructured surface relief are surface-embedded in layered multispectral luminescent media containing organic dyes and NaYF 4 :Yb 3+ ,Er 3+ nanocrystals as downshifting and upconverting luminophores, respectively, via printing-enabled deterministic materials assembly. The ultrathin nanostructured silicon microcells in the composite luminescent waveguide exhibit strongly augmented photocurrent (∼40.1 mA/cm 2 ) and energy conversion efficiency (∼12.8%) than devices with only a single type of luminescent species, owing to the synergistic contributions from optical downshifting, plasmonically enhanced upconversion, and waveguided photon flux for optical concentration, where the short-circuit current density increased by ∼13.6 mA/cm 2 compared with microcells in a nonluminescent medium on a plain silver reflector under a confined illumination.

Synergistically Enhanced Performance of Ultrathin Nanostructured Silicon Solar Cells Embedded in Plasmonically Assisted, Multispectral Luminescent Waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sung-Min; Dhar, Purnim; Chen, Huandong

Ultrathin silicon solar cells fabricated by anisotropic wet chemical etching of single-crystalline wafer materials represent an attractive materials platform that could provide many advantages for realizing high-performance, low-cost photovoltaics. However, their intrinsically limited photovoltaic performance arising from insufficient absorption of low-energy photons demands careful design of light management to maximize the efficiency and preserve the cost-effectiveness of solar cells. Herein we present an integrated flexible solar module of ultrathin, nanostructured silicon solar cells capable of simultaneously exploiting spectral upconversion and downshifting in conjunction with multispectral luminescent waveguides and a nanostructured plasmonic reflector to compensate for their weak optical absorption andmore » enhance their performance. The 8 μm-thick silicon solar cells incorporating a hexagonally periodic nanostructured surface relief are surface-embedded in layered multispectral luminescent media containing organic dyes and NaYF4:Yb3+,Er3+ nanocrystals as downshifting and upconverting luminophores, respectively, via printing-enabled deterministic materials assembly. The ultrathin nanostructured silicon microcells in the composite luminescent waveguide exhibit strongly augmented photocurrent (~40.1 mA/cm2) and energy conversion efficiency (~12.8%) than devices with only a single type of luminescent species, owing to the synergistic contributions from optical downshifting, plasmonically enhanced upconversion, and waveguided photon flux for optical concentration, where the short-circuit current density increased by ~13.6 mA/cm2 compared with microcells in a nonluminescent medium on a plain silver reflector under a confined illumination.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagglund, Carl; Zeltzer, Gabriel; Ruiz, Ricardo

In this study, when optical resonances interact strongly, hybridized modes are formed with mixed properties inherited from the basic modes. Strong coupling therefore tends to equalize properties such as damping and oscillator strength of the spectrally separate resonance modes. This effect is here shown to be very useful for the realization of near-perfect dual-band absorption with ultrathin (~10 nm) layers in a simple geometry. Absorber layers are constructed by atomic layer deposition of the heavy-damping semiconductor tin monosulfide (SnS) onto a two-dimensional gold nanodot array. In combination with a thin (55 nm) SiO 2 spacer layer and a highly reflectivemore » Al film on the back, a semiopen nanocavity is formed. The SnS-coated array supports a localized surface plasmon resonance in the vicinity of the lowest order antisymmetric Fabry–Perot resonance of the nanocavity. Very strong coupling of the two resonances is evident through anticrossing behavior with a minimum peak splitting of 400 meV, amounting to 24% of the plasmon resonance energy. The mode equalization resulting from this strong interaction enables simultaneous optical impedance matching of the system at both resonances and thereby two near-perfect absorption peaks, which together cover a broad spectral range. When paired with the heavy damping from SnS band-to-band transitions, this further enables approximately 60% of normal incident solar photons with energies exceeding the band gap to be absorbed in the 10 nm SnS coating. Thereby, these results establish a distinct relevance of strong coupling phenomena to efficient, nanoscale photovoltaic absorbers and more generally for fulfilling a specific optical condition at multiple spectral positions.« less

Multilayer-Grown Ultrathin Nanostructured GaAs Solar Cells as a Cost-Competitive Materials Platform for III-V Photovoltaics.

PubMed

Gai, Boju; Sun, Yukun; Lim, Haneol; Chen, Huandong; Faucher, Joseph; Lee, Minjoo L; Yoon, Jongseung

2017-01-24

Large-scale deployment of GaAs solar cells in terrestrial photovoltaics demands significant cost reduction for preparing device-quality epitaxial materials. Although multilayer epitaxial growth in conjunction with printing-based materials assemblies has been proposed as a promising route to achieve this goal, their practical implementation remains challenging owing to the degradation of materials properties and resulting nonuniform device performance between solar cells grown in different sequences. Here we report an alternative approach to circumvent these limitations and enable multilayer-grown GaAs solar cells with uniform photovoltaic performance. Ultrathin single-junction GaAs solar cells having a 300-nm-thick absorber (i.e., emitter and base) are epitaxially grown in triple-stack releasable multilayer assemblies by molecular beam epitaxy using beryllium as a p-type impurity. Microscale (∼500 × 500 μm 2 ) GaAs solar cells fabricated from respective device layers exhibit excellent uniformity (<3% relative) of photovoltaic performance and contact properties owing to the suppressed diffusion of p-type dopant as well as substantially reduced time of epitaxial growth associated with ultrathin device configuration. Bifacial photon management employing hexagonally periodic TiO 2 nanoposts and a vertical p-type metal contact serving as a metallic back-surface reflector together with specialized epitaxial design to minimize parasitic optical losses for efficient light trapping synergistically enable significantly enhanced photovoltaic performance of such ultrathin absorbers, where ∼17.2% solar-to-electric power conversion efficiency under simulated AM1.5G illumination is demonstrated from 420-nm-thick single-junction GaAs solar cells grown in triple-stack epitaxial assemblies.

3-D matrix template-assisted growth of oriented oxide nanowire arrays using glancing angle pulsed laser deposition

NASA Astrophysics Data System (ADS)

Wright, N.; Mateo-Feliciano, D.; Ostoski, A.; Mukherjee, P.; Witanachchi, S.

Nanosphere lithography is a combination of different methods to nanofabrication. In this work nanosphere lithography is used to study the growth of Zinc Oxide Nano-columns (ZnO NCs) on different diameter Silica Nanosphere (SNS) self-assembled templates. ZnO NCs are promising building blocks for many existing and emerging optical, electrical, and piezoelectric devices, specifically, the seeded growth of other oxide materials. Recently, reports have shown a ferroelectric phase of zinc stannate (ZnSnO3) and while lead zirconium titanate oxide (PZT) has been the main material of interest in ferroelectric and piezoelectric applications, the toxicity of lead has been of great concern. The possibility of developing lead free piezoelectric materials is of great interest in the ferroelectric community. Langmuir-Blodgett method was used to construct a self-assembled monolayer of SNSs on silicon substrates. Oriented ZnO NCs were grown on top of the spheres using the glancing angle pulsed laser deposition technique. Columns were formed in a spatially ordered closed-packed hexagonal configuration. Growth of ZnO NCs was studied as function of ambient Oxygen pressure with SNS size ranging from 250-1000 nm. Cross-sectional Scanning Electron Microscopy and X-ray diffraction (XRD) were used to study the template structure. Relative aspect ratios were studied and showed tunability of column dimensions with sphere size. XRD revealed ZnO NC arrays were c-axis oriented with hexagonal wurtzite structure.

Franckeite as a naturally occurring van der Waals heterostructure

PubMed Central

Molina-Mendoza, Aday J.; Giovanelli, Emerson; Paz, Wendel S.; Niño, Miguel Angel; Island, Joshua O.; Evangeli, Charalambos; Aballe, Lucía; Foerster, Michael; van der Zant, Herre S. J.; Rubio-Bollinger, Gabino; Agraït, Nicolás; Palacios, J. J.; Pérez, Emilio M.; Castellanos-Gomez, Andres

2017-01-01

The fabrication of van der Waals heterostructures, artificial materials assembled by individual stacking of 2D layers, is among the most promising directions in 2D materials research. Until now, the most widespread approach to stack 2D layers relies on deterministic placement methods, which are cumbersome and tend to suffer from poor control over the lattice orientations and the presence of unwanted interlayer adsorbates. Here, we present a different approach to fabricate ultrathin heterostructures by exfoliation of bulk franckeite which is a naturally occurring and air stable van der Waals heterostructure (composed of alternating SnS2-like and PbS-like layers stacked on top of each other). Presenting both an attractive narrow bandgap (<0.7 eV) and p-type doping, we find that the material can be exfoliated both mechanically and chemically down to few-layer thicknesses. We present extensive theoretical and experimental characterizations of the material's electronic properties and crystal structure, and explore applications for near-infrared photodetectors. PMID:28194037

Unlocking the potential of SnS2: Transition metal catalyzed utilization of reversible conversion and alloying reactions

NASA Astrophysics Data System (ADS)

Huang, Zhi Xiang; Wang, Ye; Liu, Bo; Kong, Dezhi; Zhang, Jun; Chen, Tupei; Yang, Hui Ying

2017-01-01

The alloying-dealloying reactions of SnS2 proceeds with the initial conversion reaction of SnS2 with lithium that produces Li2S. Unfortunately, due to the electrochemical inactivity of Li2S, the conversion reaction of SnS2 is irreversible, which significantly limit its potential applications in lithium-ion batteries. Herein, a systematic understanding of transition metal molybdenum (Mo) as a catalyst in SnS2 anode is presented. It is found that Mo catalyst is able to efficiently promote the reversible conversion of Sn to SnS2. This leads to the utilization of both conversion and alloying reactions in SnS2 that greatly increases lithium storage capability of SnS2. Mo catalyst is introduced in the form of MoS2 grown directly onto self-assembled vertical SnS2 nanosheets that anchors on three-dimensional graphene (3DG) creating a hierarchal nanostructured named as SnS2/MoS2/3DG. The catalytic effect results in a significantly enhanced electrochemical properties of SnS2/MoS2/3DG; a high initial Coulombic efficiency (81.5%) and high discharge capacities of 960.5 and 495.6 mA h g-1 at current densities of 50 and 1000 mA g-1, respectively. Post cycling investigations using ex situ TEM and XPS analysis verifies the successful conversion reaction of SnS2 mediated by Mo. The successful integration of catalyst on alloying type metal sulfide anode creates a new avenue towards high energy density lithium anodes.

Unlocking the potential of SnS2: Transition metal catalyzed utilization of reversible conversion and alloying reactions.

PubMed

Huang, Zhi Xiang; Wang, Ye; Liu, Bo; Kong, Dezhi; Zhang, Jun; Chen, Tupei; Yang, Hui Ying

2017-01-19

The alloying-dealloying reactions of SnS 2 proceeds with the initial conversion reaction of SnS 2 with lithium that produces Li 2 S. Unfortunately, due to the electrochemical inactivity of Li 2 S, the conversion reaction of SnS 2 is irreversible, which significantly limit its potential applications in lithium-ion batteries. Herein, a systematic understanding of transition metal molybdenum (Mo) as a catalyst in SnS 2 anode is presented. It is found that Mo catalyst is able to efficiently promote the reversible conversion of Sn to SnS 2 . This leads to the utilization of both conversion and alloying reactions in SnS 2 that greatly increases lithium storage capability of SnS 2 . Mo catalyst is introduced in the form of MoS 2 grown directly onto self-assembled vertical SnS 2 nanosheets that anchors on three-dimensional graphene (3DG) creating a hierarchal nanostructured named as SnS 2 /MoS 2 /3DG. The catalytic effect results in a significantly enhanced electrochemical properties of SnS 2 /MoS 2 /3DG; a high initial Coulombic efficiency (81.5%) and high discharge capacities of 960.5 and 495.6 mA h g -1 at current densities of 50 and 1000 mA g -1 , respectively. Post cycling investigations using ex situ TEM and XPS analysis verifies the successful conversion reaction of SnS 2 mediated by Mo. The successful integration of catalyst on alloying type metal sulfide anode creates a new avenue towards high energy density lithium anodes.

Carbon-doped SnS2 nanostructure as a high-efficiency solar fuel catalyst under visible light.

PubMed

Shown, Indrajit; Samireddi, Satyanarayana; Chang, Yu-Chung; Putikam, Raghunath; Chang, Po-Han; Sabbah, Amr; Fu, Fang-Yu; Chen, Wei-Fu; Wu, Chih-I; Yu, Tsyr-Yan; Chung, Po-Wen; Lin, M C; Chen, Li-Chyong; Chen, Kuei-Hsien

2018-01-12

Photocatalytic formation of hydrocarbons using solar energy via artificial photosynthesis is a highly desirable renewable-energy source for replacing conventional fossil fuels. Using an L-cysteine-based hydrothermal process, here we synthesize a carbon-doped SnS 2 (SnS 2 -C) metal dichalcogenide nanostructure, which exhibits a highly active and selective photocatalytic conversion of CO 2 to hydrocarbons under visible-light. The interstitial carbon doping induced microstrain in the SnS 2 lattice, resulting in different photophysical properties as compared with undoped SnS 2 . This SnS 2 -C photocatalyst significantly enhances the CO 2 reduction activity under visible light, attaining a photochemical quantum efficiency of above 0.7%. The SnS 2 -C photocatalyst represents an important contribution towards high quantum efficiency artificial photosynthesis based on gas phase photocatalytic CO 2 reduction under visible light, where the in situ carbon-doped SnS 2 nanostructure improves the stability and the light harvesting and charge separation efficiency, and significantly enhances the photocatalytic activity.

TiO2-SnS2 nanocomposites: solar-active photocatalytic materials for water treatment.

PubMed

Kovacic, Marin; Kusic, Hrvoje; Fanetti, Mattia; Stangar, Urska Lavrencic; Valant, Matjaz; Dionysiou, Dionysios D; Bozic, Ana Loncaric

2017-08-01

The study is aimed at evaluating TiO 2 -SnS 2 composites as effective solar-active photocatalysts for water treatment. Two strategies for the preparation of TiO 2 -SnS 2 composites were examined: (i) in-situ chemical synthesis followed by immobilization on glass plates and (ii) binding of two components (TiO 2 and SnS 2 ) within the immobilization step. The as-prepared TiO 2 -SnS 2 composites and their sole components (TiO 2 or SnS 2 ) were inspected for composition, crystallinity, and morphology using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Diffuse reflectance spectroscopy (DRS) was used to determine band gaps of immobilized TiO 2 -SnS 2 and to establish the changes in comparison to respective sole components. The activity of immobilized TiO 2 -SnS 2 composites was tested for the removal of diclofenac (DCF) in aqueous solution under simulated solar irradiation and compared with that of single component photocatalysts. In situ chemical synthesis yielded materials of high crystallinity, while their morphology and composition strongly depended on synthesis conditions applied. TiO 2 -SnS 2 composites exhibited higher activity toward DCF removal and conversion in comparison to their sole components at acidic pH, while only in situ synthesized TiO 2 -SnS 2 composites showed higher activity at neutral pH.

Editor's Highlight: Effects of Intraperitoneal Injection of SnS2 Flowers on Mouse Testicle.

PubMed

Bai, Disi; Li, Qingzhao; Xiong, Yanjie; Zhao, Junjian; Bai, Liyuan; Shen, Peijun; Yuan, Lu; Wu, Ping

2018-02-01

SnS2 nanoflowers (SnS2 NFs) have been widely used in photoelectric and catalytic applications. However, its explosure and reproductive toxicity is unknown. The aim of this study was to investigate the effect of exposure to 3 different sized-SnS2 flowers (dose: 38 mg/kg; size: 50, 80, and 200 nm) in testes of mice for 4 weeks by intraperitoneal injection. Though the body weight of mice treated or not with SnS2 NFs was not different, and SnS2 NFs were distributed to the organs including liver, kidney, spleen, heart, brain, and testis, more distribution SnS2 NFs (50 and 80 nm) were found in testicle tissues compared with SnS2 flowers (200 nm) in those tissues. The results of sperm count and survival analysis, histopathological evaluation, and qRT-PCR detection showed that there was moderate reproductive toxicity induced by the small-sized SnS2 NFs in testicle tissues. Furthermore, elevated malondialdehyde level and decreased superoxide dismutase activity were also observed in the SnS2 NFs (dose: 38 mg/kg; size: 50 and 80 nm) treated groups. Likewise, the qRT-PCR data indicated that SnS2 NFs can induce apoptosis and inflammation responses. Although the pro-inflammation marker of TNF-α, IL-1β, iNOS, and COX-2 at the mRNA levels were higher expression in 50 and 80 nm groups than that in control and 200 nm group, no statistical significance existed between 50 and 80 nm groups. Accordingly, the repeated-dose toxicity of SnS2 NFs in testicle tissues was also observed in a dose-dependent manner by intraperitoneal injection of SnS2 NFs (size: 50 nm; 0.38, 3.8, and 38 mg/kg) for 4 weeks, when determined by sperm count, survival rate, and qRT-PCR analysis. In addition, transmission electron microscopy showed that the ultrastructural abnormalities formed by the small-sized SnS2 NFs in testes were more severe than those formed by the large-sized SnS2 in testes. Taken together, these findings implied that the SnS2 NFs activated inflammation responses that signified apoptosis in murine testes. This study provided useful information for risk analysis and regulation of SnS2 NFs by administration agencies. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Hepatic, metabolic and toxicity evaluation of repeated oral administration of SnS2 nanoflowers in mice.

PubMed

Bai, Disi; Li, Qingzhao; Xiong, Yanjie; Wang, Chao; Shen, Peijun; Bai, Liyuan; Yuan, Lu; Wu, Ping

2018-05-02

Tin sulphide (SnS2) nanoflowers (NFs) with highly photocatalytic activity for wastewater treatment may lead to potential health hazards via oral routes of human exposure. No studies have reported the hepatic effects of SnS2 NFs on the metabolic function and hepatotoxicity. In this study, we examined the hepatic effects of the oral administration of SnS2 NFs (250-1000 mg/kg) to ICR mice for 14 d, with the particle size ranging from 50 to 200 nm. Serum and liver tissue samples were assayed using biochemical analysis, liver histopathology and metabolic gene expression. The different sizes of SnS2 NFs (250 mg/kg dose), such as 50, 80 and 200 nm, did not induce any adverse hepatic effect related to biochemical parameters or histopathology in the treated mice compared with controls. The oral administration of 50-nm SnS2 NFs at doses of 250, 500 and 1000 mg/kg for 14 d produced dose-dependent hepatotoxicity and inflammatory responses in treated mice. Furthermore, the expression of metabolic genes in the liver tissues was altered, supporting the SnS2 NF-related hepatotoxic phenotype. The oral administration of SnS2 NFs also produced abnormal microstructures in the livers of the treated mice. Taken together, these data indicate that the increased risk of hepatotoxicity in SnS2 NF-treated mice was independent of the particle size but was dependent on their dose. The no-observed-adverse effect level was <250 mg/kg for the 50-nm SnS2 NFs. Our study provides an experimental basis for the safe application of SnS2 NFs.

A Heterobimetallic W-Ni Complex Containing a Redox-Active W[SNS]2 Metalloligand.

PubMed

Rosenkoetter, Kyle E; Ziller, Joseph W; Heyduk, Alan F

2016-07-05

The tungsten complex W[SNS]2 ([SNS]H3 = bis(2-mercapto-4-methylphenyl)amine) was bound to a Ni(dppe) [dppe = 1,2-bis(diphenylphosphino)ethane] fragment to form the new heterobimetallic complex W[SNS]2Ni(dppe). Characterization of the complex by single-crystal X-ray diffraction revealed the presence of a short W-Ni bond, which renders the complex diamagnetic despite formal tungsten(V) and nickel(I) oxidation states. The W[SNS]2 unit acts as a redox-active metalloligand in the bimetallic complex, which displays four one-electron redox processes by cyclic voltammetry. In the presence of the organic acid 4-cyanoanilinium tetrafluoroborate, W[SNS]2Ni(dppe) catalyzes the electrochemical reduction of protons to hydrogen coincident with the first reduction of the complex.

Hierarchical ultrathin alumina membrane for the fabrication of unique nanodot arrays

NASA Astrophysics Data System (ADS)

Wang, Yuyang; Wang, Yi; Wang, Hailong; Wang, Xinnan; Cong, Ming; Xu, Weiqing; Xu, Shuping

2016-01-01

Ultrathin alumina membranes (UTAMs) as evaporation masks have been a powerful tool for the fabrication of high-density nanodot arrays and have received much attention in magnetic memory devices, photovoltaics, and nanoplasmonics. In this paper, we report the fabrication of a hierarchical ultrathin alumina membrane (HUTAM) with highly ordered submicro/nanoscale channels and its application as an evaporation mask for the realization of unique non-hexagonal nanodot arrays dependent on the geometrical features of the HUTAM. This is the first report of a UTAM with a hierarchical geometry, breaking the stereotype that only limited sets of nanopatterns can be realized using the UTAM method (with typical inter-pore distance of 100 nm). The fabrication of a HUTAM is discussed in detail. An improved, longer wet etching time than previously reported is found to effectively remove the barrier layer and widen the pores of a HUTAM. A growth sustainability issue brought about by pre-patterning is discussed. Spectral comparison was made to distinguish the UTAM nanodots and HUTAM nanodots. Our results can be an inspiration for more sophisticated applications of pre-patterned anodized aluminum oxide in photocatalysis, photovoltaics, and nanoplasmonics.

Luminescence of defects in the structural transformation of layered tin dichalcogenides

NASA Astrophysics Data System (ADS)

Sutter, P.; Komsa, H.-P.; Krasheninnikov, A. V.; Huang, Y.; Sutter, E.

2017-12-01

Layered tin sulfide semiconductors are both of fundamental interest and attractive for energy conversion applications. Sn sulfides crystallize in several stable bulk phases with different Sn:S ratios (SnS2, Sn2S3, and SnS), which can transform into phases with a lower sulfur concentration by introduction of sulfur vacancies (VS). How this complex behavior affects the optoelectronic properties remains largely unknown but is of key importance for understanding light-matter interactions in this family of layered materials. Here, we use the capability to induce VS and drive a transformation between few-layer SnS2 and SnS by electron beam irradiation, combined with in-situ cathodoluminescence spectroscopy and ab-initio calculations to probe the role of defects in the luminescence of these materials. In addition to the characteristic band-edge emission of the endpoint structures, our results show emerging luminescence features accompanying the SnS2 to SnS transformation. Comparison with calculations indicates that the most prominent emission in SnS2 with sulfur vacancies is not due to luminescence from a defect level but involves recombination of excitons bound to neutral VS in SnS2. These findings provide insight into the intrinsic and defect-related optoelectronic properties of Sn chalcogenide semiconductors.

Reactivation and reuse of TiO2-SnS2 composite catalyst for solar-driven water treatment.

PubMed

Kovacic, Marin; Kopcic, Nina; Kusic, Hrvoje; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

2018-01-01

One of the most important features of photocatalytic materials intended to be used for water treatment is their long-term stability. The study is focused on the application of thermal and chemical treatments for the reactivation of TiO 2 -SnS 2 composite photocatalyst, prepared by hydrothermal synthesis and immobilized on the glass support using titania/silica binder. Such a catalytic system was applied in solar-driven treatment, solar/TiO 2 -SnS 2 /H 2 O 2 , for the purification of water contaminated with diclofenac (DCF). The effectiveness of studied reactivation methods for retaining TiO 2 -SnS 2 activity in consecutive cycles was evaluated on basis of DCF removal and conversion, and TOC removal and mineralization of organic content. Besides these water quality parameters, biodegradability changes in DCF aqueous solution treated by solar/TiO 2 -SnS 2 /H 2 O 2 process using simply reused (air-dried) and thermally and chemically reactivated composite photocatalyst through six consecutive cycles were monitored. It was established that both thermal and chemical reactivation retain TiO 2 -SnS 2 activity in the second cycle of its reuse. However, both treatments caused the alteration in the TiO 2 -SnS 2 morphology due to the partial transformation of visible-active SnS 2 into non-active SnO 2 . Such alteration, repeated through consecutive reactivation and reuse, was reflected through gradual activity loss of TiO 2 -SnS 2 composite in applied solar-driven water treatment.

Heterobimetallic complexes of palladium and platinum containing a redox-active W[SNS]2 metalloligand.

PubMed

Rosenkoetter, Kyle E; Ziller, Joseph W; Heyduk, Alan F

2017-05-02

Complexes of the general formula W[SNS] 2 M(dppe) (M = Pd, Pt; [SNS]H 3 = bis(2-mercapto-p-tolyl)amine; dppe = 1,2-bis(diphenylphosphino)ethane) were prepared by combining the corresponding (dppe)MCl 2 synthon with W[SNS] 2 under reducing conditions. X-ray diffraction studies revealed the formation of a heterobimetallic complex supported by a single thiolate bridging ligand and a short metal-metal bond between the tungsten and palladium or platinum. Electrochemical and computational results show that the frontier orbitals lie predominantly on the W[SNS] 2 fragment suggesting that it behaves as a redox-active metalloligand in these complexes.

Template-free synthesis of novel SnS2 array and its superior performances for lithium ion battery

NASA Astrophysics Data System (ADS)

Zhu, Anquan; Qiao, Lulu; Tan, Pengfei; Ma, Yongjin; Liu, Yi; Pan, Jun

2018-05-01

A kind of novel three-dimensional SnS2 array was fabricated by an ethylenediamine (EDA) assisting low-temperature solvothermal method. It was observed that as-obtained SnS2 array was composed of numerous SnS2 nanosheets with the thickness of about 22 nm. When used as lithium ion batteries (LIBs) anode, the SnS2 array displayed remarkable capacities on rate and cycling performances, delivering the rates with reversible capacities of 763.3, 658.6, 593.6, 554.4 and 450.3 mAh g-1 at the current densities of 0.2, 0.5, 1, 2 and 5 A g-1, respectively. Moreover, the satisfactory cycling performance was also disclosed, remaining capacity of 547.8 mAh g-1 after 100th cycle at 0.2 A g-1, better than some reported pure SnS2 nanostructures. Based on the characterization and experimental results, the reasons of such superior electrochemical performances were determined and elaborated. It means that the SnS2 array possesses promising potential on the renewable energy field.

Simple eco-friendly synthesis of the surfactant free SnS nanocrystal toward the photoelectrochemical cell application.

PubMed

Huang, Xiaoguang; Woo, Heechul; Wu, Peinian; Hong, Hyo Jin; Jung, Wan Gil; Kim, Bong-Joong; Vanel, Jean-Charles; Choi, Jin Woo

2017-11-28

A simple, low cost, non-toxic and eco-friendly pathway for synthesizing efficient sunlight-driven tin sulfide photocatalyst was studied. SnS nanocrystals were prepared by using mechanical method. The bulk SnS was obtained by evaporation of SnS nanocrystal solution. The synthesized samples were characterized by using XRD, SEM, TEM, UV-vis, and Raman analyses. Well crystallized SnS nanocrystals were verified and the electrochemical characterization was also performed under visible light irradiation. The SnS nanocrystals have shown remarkable photocurrent density of 7.6 mA cm -2 under 100 mW cm -2 which is about 10 times larger than that of the bulk SnS under notably stable operation conditions. Furthermore, the SnS nanocrystals presented higher stability than the bulk form. The IPCE(Incident photon to current conversion efficiency) of 9.3% at 420 nm was obtained for SnS nanocrystal photoanode which is strikingly higher than that of bulk SnS, 0.78%. This work suggests that the enhancement of reacting area by using SnS nanocrystal absorbers could give rise to the improvement of photoelectrochemical cell efficiency.

Preparation and characterization of Cu2SnS3 thin films by electrodeposition

NASA Astrophysics Data System (ADS)

Patel, Biren; Narasimman, R.; Pati, Ranjan K.; Mukhopadhyay, Indrajit; Ray, Abhijit

2018-05-01

Cu2SnS3 thin films were electrodeposited on F:SnO2/Glass substrates at room temperature by using aqueous solution. Copper and tin were first electrodeposited from single bath and post annealed in the presence of sulphur atmosphere to obtain the Cu2SnS3 phase. The Cu2SnS3 phase with preferred orientation along the (112) crystal direction grows to greater extent by the post annealing of the film. Raman analysis confirms the monoclinic crystal structure of Cu2SnS3 with principle mode of vibration as A1 (symmetric breathing mode) corresponding to the band at 291 cm-1. It also reveals the benign coexistence of orthorhombic Cu3SnS4 and Cu2SnS7 phases. Optical properties of the film show direct band gap of 1.25 eV with a high absorption coefficient of the order of 104 cm-1 in the visible region. Photo activity of the electrodeposited film was established in two electrode photoelectro-chemical cell, where an open circuit voltage of 91.6 mV and a short circuit current density of 10.6 µA/cm2 were recorded. Fabrication of Cu2SnS3 thin film heterojunction solar cell is underway.

Effects of Na and secondary phases on physical properties of SnS thin film after sulfurization process

NASA Astrophysics Data System (ADS)

Kawano, Yu; Kodani, Yuto; Chantana, Jakapan; Minemoto, Takashi

2016-09-01

2.48%-efficient SnS thin film solar cell is obtained under thermal evaporation method by optimizing growth temperature. The method to fabricate SnS films is limited by growth temperature, which should not be over 200 °C to prevent re-evaporation of SnS. To further enhance SnS grains, SnS films were annealed in H2S gas from 200 to 500 °C, namely sulfurization process. SnS grain size was increased with sulfurization temperature of above 400 °C however, secondary phase grains on film’s surface were observed owing to the accumulated Na, diffused from soda-lime glass substrate into the film, thus deteriorating film’s quality, implied by Urbach energy.

Sex differences in the association of social network satisfaction and the risk for type 2 diabetes.

PubMed

Lukaschek, K; Baumert, J; Kruse, J; Meisinger, C; Ladwig, K H

2017-05-02

The role of an individual's social network satisfaction (SNS) in the association of social isolation or living alone and incident type 2 diabetes (T2D) is unclear. We assessed the association of SNS with incident T2D and analysed potential modifications of the SNS-T2D association by social isolation or living alone. The study population (N = 6839 aged 25-74 years without diabetes at baseline) derived from the prospective population-based MONICA/KORA study (1989-2009). Social network satisfaction was assessed by a single item. Cox regression was used to estimate hazard ratios (HR) for SNS separately in men and women. In men with low SNS, risk for incident T2D increased significantly (HR: 2.15, 95% CI: 1.33-3.48, p value 0.002). After additional adjustments for social isolation or living alone, the risk for incident T2D was still significant, albeit less pronounced (HRs 1.85 or 2.05, p values 0.001 or 0.004). The interaction analysis showed an increased T2D risk effect for low SNS compared to high SNS in women living in a partnership (HR: 2.11, 95% CI: 1.00-4.44, p value for interaction: 0.047) and for moderate SNS compared to high SNS in socially connected women (1.56, 1.01-2.39, 0.010). Further research is needed to address the complexities of the perception of social relationships and social interactions, or interdependence, especially when another major public health issue such as T2D is concerned.

SnS2 films deposited from molecular ink as Cd-free alternative buffer layer for solar cells

NASA Astrophysics Data System (ADS)

Jariwala, Akshay; Chaudhuri, Tapas K.; Toshniwal, Aditi; Patel, Sanjay; Kheraj, Vipul; Ray, Abhijit

2018-05-01

This work investigates the potential of SnS2 as a Cd-free alternative buffer layer for CIGS solar cells. The suitability of SnS2 film as a buffer layer has been evaluated by numerical analysis using SCAPS software. A new simple method for preparation of SnS2 films by dip-coating from molecular ink is reported. The formation of SnS2 is confirmed by Raman spectroscopy. The films are smooth and shiny with roughness of 2-3 nm. The films are n-type with band gap of 2.6 eV and electrical conductivity of 10-3 S/cm.

Introducing Overlapping Grain Boundaries in Chemical Vapor Deposited Hexagonal Boron Nitride Monolayer Films

PubMed Central

2017-01-01

We demonstrate the growth of overlapping grain boundaries in continuous, polycrystalline hexagonal boron nitride (h-BN) monolayer films via scalable catalytic chemical vapor deposition. Unlike the commonly reported atomically stitched grain boundaries, these overlapping grain boundaries do not consist of defect lines within the monolayer films but are composed of self-sealing bilayer regions of limited width. We characterize this overlapping h-BN grain boundary structure in detail by complementary (scanning) transmission electron microscopy techniques and propose a catalytic growth mechanism linked to the subsurface/bulk of the process catalyst and its boron and nitrogen solubilities. Our data suggest that the overlapping grain boundaries are comparatively resilient against deleterious pinhole formation associated with grain boundary defect lines and thus may reduce detrimental breakdown effects when polycrystalline h-BN monolayer films are used as ultrathin dielectrics, barrier layers, or separation membranes. PMID:28410557

Template-free fabrication of hierarchical macro/mesoporpous SnS2/TiO2 composite with enhanced photocatalytic degradation of Methyl Orange (MO)

NASA Astrophysics Data System (ADS)

Dai, Gaopeng; Qin, Haiquan; Zhou, Huan; Wang, Wanqiang; Luo, Tianxiong

2018-02-01

Ordered macro/mesoporous SnS2/TiO2 composite was successfully prepared via a template-free aqueous technique using tetrabutyl titanate as the titanium precursor and SnCl4•5H2O as the tin precursor. The photocatalytic activity of SnS2/TiO2 composite was tested by the degradation of Methyl Orange (MO) aqueous solution under irradiation of the simulated sunlight. It was found that SnS2/TiO2 composite displayed an enhanced photocatalytic activity with a 0.055 min-1 apparent rate constant (degradation efficiency of 90.9% within 50 min). The ordered macro/mesoporous structure and SnS2/TiO2 heterostructure were considered to play synergistic effects in its enhanced photocatalytic performance, because the ordered porous structure can improve mass transfer and light capture, and heterostructure between SnS2 and TiO2 can reduce the recombination rate of photogenerated electrons and holes.

Low-Temperature Electrical Characteristics of Si-Based Device with New Tetrakis NiPc-SNS Active Layer

NASA Astrophysics Data System (ADS)

Yavuz, Arzu Büyükyağci; Carbas, Buket Bezgın; Sönmezoğlu, Savaş; Soylu, Murat

2016-01-01

A new tetrakis 4-(2,5-di-2-thiophen-2-yl-pyrrol-1-yl)-substituted nickel phthalocyanine (NiPc-SNS) has been synthesized. This synthesized NiPc-SNS thin film was deposited on p-type Si substrate using the spin coating method (SCM) to fabricate a NiPc-SNS/ p-Si heterojunction diode. The temperature-dependent electrical characteristics of the NiPc-SNS/ p-Si heterojunction with good rectifying behavior were investigated by current-voltage ( I- V) measurements between 50 K and 300 K. The results indicate that the ideality factor decreases while the barrier height increases with increasing temperature. The barrier inhomogeneity across the NiPc-SNS/ p-Si heterojunction reveals a Gaussian distribution at low temperatures. These results provide further evidence of the more complicated mechanisms occurring in this heterojunction. Based on these findings, NiPc-SNS/ p-Si junction diodes are feasible for use in low-temperature applications.

Synthesis and Raman analysis of SnS nanoparticles synthesized by PVP assisted polyol method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baby, Benjamin Hudson; Mohan, D. Bharathi, E-mail: d.bharathimohan@gmail.com

2015-06-24

SnS film was prepared by a simple drop casting method after synthesizing SnS nanoparticles by using PVP assisted polyol method. Confocal Raman study was carried out for the as deposited and annealed (150, 300 and 400 °C) films at two different excitation wavelengths 514 and 785 nm. At the excitation wavelength of 514 nm, the Raman modes showed for a mixed phase of SnS and SnS{sub 2} up to 150 °C and then only a pure SnS phase was observed up to 400 °C due to the dissociation of SnS{sub 2} in to SnS by releasing S. The increase in intensity ofmore » Raman (A{sub g} and B{sub 3g}) as well as IR (B{sub 3u}) active modes of SnS are observed with increasing annealing temperature at excitation wavelength 785 nm due to the increased crystallinity and inactiveness of SnS{sub 2} modes. X-ray diffraction confirming the formation of a single phase of SnS while the greater homogeneity in both size and shape of SnS nanoparticles were confirmed through surface morphology from SEM.« less

Thickness-dependently enhanced photodetection performance of vertically grown SnS2 nanoflakes with large size and high production.

PubMed

Jia, Xiansheng; Tang, Chengchun; Pan, Ruhao; Long, Yun-Ze; Gu, Changzhi; Li, Junjie

2018-05-10

Photodetection based on Two-dimensional (2D) SnS2 has attracted a growing interest due to its superiority in response rate and responsivity, but high-quality growth and high performance photodetecting of 2D SnS2still face great challenges. Here, high-quality SnS2 nanoflakes with large-size and high-production are vertically grown on Si substrate by a modified CVD method, having an average size of 30 m with different thicknesses. Then a single SnS2 nanoflake-based phototransistor was fabricated to obtain a high current on/off ratio of 107 and excellent performances in photodetection, including fast response rates, low dark current, high responsivity and detectivity. Specifically, the SnS2 nanoflakes show the thickness-dependent photodetection capability and the highest responsivity of 354.4 A W-1 is obtained at the average thickness of 100.5 nm. A sensitized process using HfO2 nanolayer can further enhance the responsivity up to 1922 A W-1. Our work provides an efficient path to select SnS2 crystal samples with the optimal thickness as promising candidates for high-performance optoelectronic applications.

Low-Temperature Wafer-Scale Deposition of Continuous 2D SnS2 Films.

PubMed

Mattinen, Miika; King, Peter J; Khriachtchev, Leonid; Meinander, Kristoffer; Gibbon, James T; Dhanak, Vin R; Räisänen, Jyrki; Ritala, Mikko; Leskelä, Markku

2018-04-19

Semiconducting 2D materials, such as SnS 2 , hold immense potential for many applications ranging from electronics to catalysis. However, deposition of few-layer SnS 2 films has remained a great challenge. Herein, continuous wafer-scale 2D SnS 2 films with accurately controlled thickness (2 to 10 monolayers) are realized by combining a new atomic layer deposition process with low-temperature (250 °C) postdeposition annealing. Uniform coating of large-area and 3D substrates is demonstrated owing to the unique self-limiting growth mechanism of atomic layer deposition. Detailed characterization confirms the 1T-type crystal structure and composition, smoothness, and continuity of the SnS 2 films. A two-stage deposition process is also introduced to improve the texture of the films. Successful deposition of continuous, high-quality SnS 2 films at low temperatures constitutes a crucial step toward various applications of 2D semiconductors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Large-area synthesis of WSe2 from WO3 by selenium-oxygen ion exchange

NASA Astrophysics Data System (ADS)

Browning, Paul; Eichfeld, Sarah; Zhang, Kehao; Hossain, Lorraine; Lin, Yu-Chuan; Wang, Ke; Lu, Ning; Waite, A. R.; Voevodin, A. A.; Kim, Moon; Robinson, Joshua A.

2015-03-01

Few-layer tungsten diselenide (WSe2) is attractive as a next-generation electronic material as it exhibits modest carrier mobilities and energy band gap in the visible spectra, making it appealing for photovoltaic and low-powered electronic applications. Here we demonstrate the scalable synthesis of large-area, few-layer WSe2 via replacement of oxygen in hexagonally stabilized tungsten oxide films using dimethyl selenium. Cross-sectional transmission electron microscopy reveals successful control of the final WSe2 film thickness through control of initial tungsten oxide thickness, as well as development of layered films with grain sizes up to several hundred nanometers. Raman spectroscopy and atomic force microscopy confirms high crystal uniformity of the converted WSe2, and time domain thermo-reflectance provide evidence that near record low thermal conductivity is achievable in ultra-thin WSe2 using this method.

Development of SnS2/RGO nanosheet composite for cost-effective aqueous hybrid supercapacitors.

PubMed

Chauhan, Himani; Singh, Manoj K; Kumar, Praveen; Hashmi, Safir Ahmad; Deka, Sasanka

2017-01-13

The development of low cost supercapacitor cells with unique capacitive properties is essential for many domestic and industrial purposes. Here we report the first ever application of SnS 2 -reduced graphene oxide (SnS 2 /RGO) layered nanocomposite as a superior electrode material for symmetric aqueous hybrid supercapacitors. We synthesized SnS 2 /RGO nanocomposite comprised of nanosheets of SnS 2 and graphene oxide via a one-pot hydrothermal approach. in situ as-synthesized SnS 2 /RGO is devised for the first time to give high specific capacitance 500 Fg -1 , energy density 16.67 Wh kg -1 and power density 488 W kg -1 . The cell retains 95% charge/discharge cycle stability up to 1000 cycles. In-short, the SnS 2 /RGO nanosheet composite presented is a novel and advanced material for application in high stability moderate value hybrid supercapacitors. All the currently available surveys in literature state the potential applicability of SnS 2 as the anode material for reversible lithium/sodium ion batteries (LIBs/NIBs) but there is a lack of equivalent studies on electrochemical capacitors. We filled up this knowledge gap by the use of the same material in a cost-effective, highly active hybrid supercapacitor application by utilizing its pseudocapacitance property combined with the layered capacitance property of graphene sheets.

Very large cooperative effects in heterobimetallic titanium-chromium catalysts for ethylene polymerization/copolymerization.

PubMed

Liu, Shaofeng; Motta, Alessandro; Mouat, Aidan R; Delferro, Massimiliano; Marks, Tobin J

2014-07-23

The heterobimetallic complexes, (η(5)-indenyl)[1-Me2Si((t)BuN)TiCl2]-3-CnH2n-[N,N-bis(2-(ethylthio)ethyl)amine]CrCl3 (n = 0, Ti-C0-Cr(SNS); n = 2, Ti-C2-Cr(SNS); n = 6, Ti-C6-Cr(SNS)), (η(5)-indenyl)[1-Me2Si((t)BuN)TiCl2]-3-C2H4-[N,N-bis((o-OMe-C6H4)2P)amine]CrCl3 (Ti-C2-Cr(PNP)), and (η(5)-indenyl)[1-Me2Si((t)BuN)TiCl2]-3-C2H4-[N,N-bis((diethylamine)ethyl)-amine]CrCl3 (Ti-C2-Cr(NNN)), are synthesized, fully characterized, and employed as olefin polymerization catalysts. With ethylene as the feed and MAO as cocatalyst/activator, SNS-based complexes Ti-C0-Cr(SNS), Ti-C2-Cr(SNS), and Ti-C6-Cr(SNS) afford linear low-density polyethylenes (LLDPEs) with exclusive n-butyl branches (6.8-25.8 branches/1000 C), while under identical polymerization conditions Ti-C2-Cr(PNP) and Ti-C2-Cr(NNN) produce polyethylenes with heterogeneous branching (C2, C4, and C≥6) or negligible branching, respectively. Under identical ethylene polymerization conditions, Ti-C0-Cr(SNS) produces polyethylenes with higher activity (4.5× and 6.1×, respectively), Mn (1.3× and 1.8×, respectively), and branch density (1.4× and 3.8×, respectively), than Ti-C2-Cr(SNS) and Ti-C6-Cr(SNS). Versus a CGC(Et)Ti + SNSCr tandem catalyst, Ti-C0-Cr(SNS) yields polyethylene with somewhat lower activity, but with 22.6× higher Mn and 4.0× greater branching density under identical conditions. In ethylene +1-pentene competition experiments, Ti-C0-Cr(SNS) yields 5.5% n-propyl branches and 94.5% n-butyl branches at [1-pentene] = 0.1 M, and the estimated effective local concentration of 1-hexene is ∼8.6 M. In contrast, the tandem CGC(Et)Ti + SNSCr system yields 91.0% n-propyl branches under identical reaction conditions. The homopolymerization and 1-pentene competition results argue that close Ti···Cr spatial proximity together with weak C-H···Ti and C-H···S interactions significantly influence relative 1-hexene enchainment and chain transfer rates, supported by DFT computation, and that such effects are conversion insensitive but cocatalyst and solvent sensitive.

Plasma-panel based detectors

NASA Astrophysics Data System (ADS)

Friedman, Peter

2017-09-01

The plasma panel sensor (PPS) is a novel micropattern gas detector inspired by plasma display panels (PDPs), the core component of plasma-TVs. A PDP comprises millions of discrete cells per square meter, each of which, when provided with a signal pulse, can initiate and sustain a plasma discharge. Configured as a detector, a pixel or cell is biased to discharge when a free-electron is generated in the gas. The PPS consists of an array of small plasma discharge pixels, and can be configured to have either an ``open-cell'' or ``closed-cell'' structure, operating with high gain in the Geiger region. We describe both configurations and their application to particle physics. The open-cell PPS lends itself to ultra-low-mass, ultrathin structures, whereas the closed-cell microhexcavity PPS is capable of higher performance. For the ultrathin-PPS, we are fabricating 3-inch devices based on two types of extremely thin, inorganic, transparent, substrate materials: one being 8-10 µm thick, and the other 25-27 µm thick. These gas-filled ultrathin devices are designed to operate in a beam-line vacuum environment, yet must be hermetically-sealed and gas-filled in an ambient environment at atmospheric pressure. We have successfully fabricated high resolution, submillimeter pixel electrodes on both types of ultrathin substrates. We will also report on the fabrication, staging and operation of the first microhexcavity detectors (µH-PPS). The first µH-PPS prototype devices have a 16 by 16 matrix of closed packed hexagon pixels, each having a 2 mm width. Initial tests of these detectors, conducted with Ne based gases at atmospheric pressure, indicate that each pixel responds independent of its neighboring cells, producing volt level pulse amplitudes in response to ionizing radiation. Results will include the hit rate response to a radioactive beta source, cosmic ray muons, the background from spontaneous discharge, pixel isolation and uniformity, and efficiency measurements. This work was funded in part by a DOE Office of Nuclear Physics SBIR Phase-II Grant.

Tuning band gap of monolayer and bilayer SnS2 by strain effect and external electric field: A first principles calculations

NASA Astrophysics Data System (ADS)

Rahman, Abeera; Shin, Young-Han

Recently many efforts have been paid to two-dimensional layered metal dichalcogenides (LMDs). Among them MoS2 has become a prototype LMD, and recent studies show surprising and rich new physics emerging in other van der Waals materials such as layered SnS2 [1-4]. SnS2 is a semiconducting earth-abundant material and Sn is a group IV element replacing the transition metal in MoS2. SnS2 shows new possibilities in various potential applications. However, the knowledge on basic properties of layered SnS2 is still not well understood. In this study, we consider two types of structures; 1T with P 3 m 1 (164) space group and 1H with P63 / mmc (194) space group. Our first principles calculations show that the 1T structure for SnS2 is more stable than the 1H structure whereas latter is more stable for MoS2. Moreover,in contrast to MoS2,SnS2 shows an indirect band gap both for 1T and 1H structures while 1T MoS2 is metallic and 1H has a direct band gap. We also study strain effect in the range of 0-10% on the band structure for monolayer and bilayer SnS2 (both for 1T and 1H structures).We find significant change in their band gaps. We also investigate the bilayer SnS2 with and without out-of-plane stress. This research was supported by Brain Korea 21 Plus Program and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and future Planning (NRF-2014M3A7B4049367, NRF-2014R1A2A1A1105089).

Twisted ultrathin silicon nanowires: A possible torsion electromechanical nanodevice

NASA Astrophysics Data System (ADS)

Garcia, J. C.; Justo, J. F.

2014-11-01

Nanowires have been considered for a number of applications in nanometrology. In such a context, we have explored the possibility of using ultrathin twisted nanowires as torsion nanobalances to probe forces and torques at molecular level with high precision, a nanoscale system analogous to the Coulomb's torsion balance electrometer. In order to achieve this goal, we performed a first-principles investigation on the structural and electronic properties of twisted silicon nanowires, in their pristine and hydrogenated forms. The results indicated that wires with pentagonal and hexagonal cross-sections are the thinnest stable silicon nanostructures. Additionally, all wires followed a Hooke's law behavior for small twisting deformations. Hydrogenation leads to spontaneous twisting, but with angular spring constants considerably smaller than the ones for the respective pristine forms. We observed considerable changes on the nanowire electronic properties upon twisting, which allows to envision the possibility of correlating the torsional angular deformation with the nanowire electronic transport. This could ultimately allow a direct access to measurements on interatomic forces at molecular level.

Monte Carlo simulation of magnetic properties of mixed spin (3/2, 1) ferromagnetic and ferrimagnetic disordered binary alloys with amorphous structure

NASA Astrophysics Data System (ADS)

Motlagh, H. Nakhaei; Rezaei, G.

2018-01-01

Monte Carlo simulation is used to study the magnetic properties of mixed spin (3/2, 1) disordered binary alloys on simple cubic, hexagonal and amorphous magnetic ultra-thin films with 18 × 18 × 2 atoms. To this end, at the first approximation, the exchange coupling interaction between the spins is considered as a constant value and at the second one, the Ruderman-Kittel-Kasuya-Yosida (RKKY) model is used. Effects of concentration, structure, exchange interaction, single ion-anisotropy and the film size on the magnetic properties of disordered ferromagnetic and ferrimagnetic binary alloys are investigated. Our results indicate that the spontaneous magnetization and critical temperatures of rare earth-3d transition binary alloys are affected by these parameters. It is also found that in the ferrimagnetic state, the compensation temperature (Tcom) and the magnetic rearrangement temperature (TR) appear for some concentrations.

A three-dimensional self-assembled SnS 2 -nano-dots@graphene hybrid aerogel as an efficient polysulfide reservoir for high-performance lithium–sulfur batteries

DOE PAGES

Luo, Liu; Chung, Sheng-Heng; Manthiram, Arumugam

2018-01-01

A free-standing self-assembled graphene aerogel embedded with SnS 2 nano-dots (SnS 2 -ND@G) is established as an efficient substrate for high-loading sulfur cathodes with synergistically physical and chemical polysulfide-trapping capability.

A three-dimensional self-assembled SnS 2 -nano-dots@graphene hybrid aerogel as an efficient polysulfide reservoir for high-performance lithium–sulfur batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Liu; Chung, Sheng-Heng; Manthiram, Arumugam

A free-standing self-assembled graphene aerogel embedded with SnS 2 nano-dots (SnS 2 -ND@G) is established as an efficient substrate for high-loading sulfur cathodes with synergistically physical and chemical polysulfide-trapping capability.

Facile and fast synthesis of SnS2 nanoparticles by pulsed laser ablation in liquid

NASA Astrophysics Data System (ADS)

Johny, J.; Sepulveda-Guzman, S.; Krishnan, B.; Avellaneda, D.; Shaji, S.

2018-03-01

Nanoparticles (NPs) of tin disulfide (SnS2) were synthesized using pulsed laser ablation in liquid (PLAL) technique. Effects of different liquid media and ablation wavelengths on the morphology and optical properties of the nanoparticles were studied. Nd: YAG laser wavelengths of 532 nm and 1064 nm (frequency 10 Hz and pulse width 10 ns) were used to irradiate SnS2 target immersed in liquid for the synthesis of SnS2 nanoparticles. Here PLAL was a fast synthesis technique, the ablation was only for 30 s. Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-vis absorption spectroscopy and photoluminescence spectroscopy were used to characterize the SnS2 NPs. TEM images showed that the liquid medium and laser wavelength influence the morphology of the NPs. SAED patterns and high resolution TEM (HRTEM) images confirmed the crystallinity of the particles. XRD and XPS analyses confirmed that SnS2 NPs were having exact crystalline structure and chemical states as that of the target. Raman analysis also supported the results obtained by XRD and XPS. Optical band gaps of the nanocolloids evaluated from their UV-vis absorption spectra were 2.4-3.05 eV. SnS2 NPs were having luminescence spectra in the blue-green region irrespective of the liquid media and ablation wavelength.

Metal-Insulator-Semiconductor Diode Consisting of Two-Dimensional Nanomaterials.

PubMed

Jeong, Hyun; Oh, Hye Min; Bang, Seungho; Jeong, Hyeon Jun; An, Sung-Jin; Han, Gang Hee; Kim, Hyun; Yun, Seok Joon; Kim, Ki Kang; Park, Jin Cheol; Lee, Young Hee; Lerondel, Gilles; Jeong, Mun Seok

2016-03-09

We present a novel metal-insulator-semiconductor (MIS) diode consisting of graphene, hexagonal BN, and monolayer MoS2 for application in ultrathin nanoelectronics. The MIS heterojunction structure was fabricated by vertically stacking layered materials using a simple wet chemical transfer method. The stacking of each layer was confirmed by confocal scanning Raman spectroscopy and device performance was evaluated using current versus voltage (I-V) and photocurrent measurements. We clearly observed better current rectification and much higher current flow in the MIS diode than in the p-n junction and the metal-semiconductor diodes made of layered materials. The I-V characteristic curve of the MIS diode indicates that current flows mainly across interfaces as a result of carrier tunneling. Moreover, we observed considerably high photocurrent from the MIS diode under visible light illumination.

Analysis of SnS2 hyperdoped with V proposed as efficient absorber material.

PubMed

Seminovski, Yohanna; Palacios, Pablo; Wahnón, Perla

2014-10-01

Intermediate-band materials can improve the photovoltaic efficiency of solar cells through the absorption of two subband-gap photons that allow extra electron-hole pair formations. Previous theoretical and experimental findings support the proposal that the layered SnS2 compound, with a band-gap of around 2 eV, is a candidate for an intermediate-band material when it is doped with a specific transition-metal. In this work we characterize vanadium doped SnS2 using density functional theory at the dilution level experimentally found and including a dispersion correction combined with the site-occupancy-disorder method. In order to analyze the electronic characteristics that depend on geometry, two SnS2 polytypes partially substituted with vanadium in symmetry-adapted non-equivalent configurations were studied. In addition the magnetic configurations of vanadium in a SnS2 2H-polytype and its comparison with a 4H-polytype were also characterized. We demonstrate that a narrow intermediate-band is formed, when these dopant atoms are located in different layers. Our theoretical predictions confirm the recent experimental findings in which a paramagnetic intermediate-band material in a SnS2 2H-polytype with 10% vanadium concentration is obtained.

Activities in Cu2S-FeS-SnS melts at 1200 °C

NASA Astrophysics Data System (ADS)

Eric, R. Hurman

1993-04-01

The dew-point technique was used to measure the vapor pressures of SnS over liquid sulfides of the system Cu2S-FeS-SnS at 1200 °C. Activities of SnS were generated from the measured vapor pressures of SnS. Activities of Cu2S and FeS were evaluated both in binary and ternary melts by Gibbs-Duhem calculations from the known SnS activity data. The systems Cu2S-SnS and Cu2S-FeS exhibit negative departures from ideal behavior, while FeS-SnS melts exhibit positive deviations.

Fabrication Of SNS Weak Links On SOS Substrates

NASA Technical Reports Server (NTRS)

Hunt, Brian D.

1995-01-01

High-quality superconductor/normal-conductor/superconductor (SNS) devices ("weak links") containing epitaxial films of YBa(2)Cu(3)O(7-x) and SrTiO(3) fabricated on silicon-on-sapphire (SOS) substrates with help of improved multilayer buffer system. Process for fabrication of edge-defined SNS weak links described in "Edge-Geometry SNS Devices Made of Y/Ba/Cu" (NPO-18552).

Enhanced cyclic stability of SnS microplates with conformal carbon coating derived from ethanol vapor deposition for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Xiang; Liu, Jiangwen; Ouyang, Liuzhang; Yuan, Bin; Yang, Lichun; Zhu, Min

2018-04-01

Carbon coated SnS microplates (SnS@C MPs) were prepared via a facile chemical vapor deposition method using SnS2 nanoflakes as precursor and ethanol vapor as carbon source. The carbon coating restrains the growth of SnS during the heat treatment. Furthermore, it improves the electronic conductivity as well as accommodates volume variations of SnS during the sodiation and desodiation processes. Therefore, the rate capability and cycle performance of the SnS@C MPs as anode materials for sodium-ion batteries are remarkably enhanced compared with the bare SnS and the SnS2 precursor. At current densities of 0.1, 0.2, 0.5, 1 and 2 A g-1, the optimized SnS@C MPs exhibit stable capacities of 602.9, 532.1, 512.2, 465.9 and 427.2 mAh g-1, respectively. At 1 A g-1, they show a reversible capacity of 528.8 mAh g-1 in the first cycle, and maintain 444.7 mAh g-1 after 50 cycles, with capacity retention of 84.1%. The carbon coating through chemical vapor deposition using ethanol vapor as carbon sources is green, simple and cost-effective, which shows great promise to improve the reversible Na+ storage of electrode materials.

Structural characterizations of pure SnS and In-doped SnS thin films using isotropic and anisotropic models

NASA Astrophysics Data System (ADS)

Kafashan, Hosein

2018-04-01

An electrochemical route has been employed to prepare pure SnS and indium-doped SnS thin films. Six samples including undoped SnS and In-doped SnS thin films deposited on the fluorine-doped tin oxide (FTO) glass substrates. An aqueous solution having SnCl2 and Na2S2O3 used as the primary electrolyte. Different In-doped SnS samples were prepared by adding a different amount of 1 mM InCl3 solution into the first electrolyte. The applied potential (E), time of deposition (t), pH and bath temperature (T) were kept at ‑1 V, 30 min, 2.1 and 60 °C, respectively. For all samples, except the In-dopant concentration, all the deposition parameters are the same. After preparation, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with an energy dispersive X-ray analyzer (EDX) attachment, atomic force microscopy (AFM), and transmission electron microscopy (TEM) were used to determine structural properties of as-deposited films. XRD patterns revealed that the synthesized undoped- and In-doped SnS thin films were crystallized in the orthorhombic structure. The shape of SnS crystals was spherical in the TEM image. X-ray peak broadening studies was done by applying Scherrer’s method, Williamson-Hall (W–H) models (including uniform deformation model (UDM), uniform strain deformation model (UDSM), and uniform deformation energy density model (UDEDM)), and size-strain plot (SSP) method. Using these techniques, the crystallite size and the lattice strains have been predicted. There was a good agreement in the particle size achieved by W–H- and SSP methods with TEM image.

Ultrathin, wafer-scale hexagonal boron nitride on dielectric surfaces by diffusion and segregation mechanism

NASA Astrophysics Data System (ADS)

Sonde, Sushant; Dolocan, Andrei; Lu, Ning; Corbet, Chris; Kim, Moon J.; Tutuc, Emanuel; Banerjee, Sanjay K.; Colombo, Luigi

2017-06-01

Chemical vapor deposition (CVD) of two-dimensional (2D) hexagonal boron nitride (h-BN) is at the center of numerous studies for its applications in novel electronic devices. However, a clear understanding of the growth mechanism is lacking for its wider industrial adoption on technologically relevant substrates such as SiO2. Here, we demonstrate a controllable growth method of thin, wafer scale h-BN films on arbitrary substrates. We also clarify the growth mechanism to be diffusion and surface segregation (D-SS) of boron (B) and nitrogen (N) in Ni and Co thin films on SiO2/Si substrates after exposure to diborane and ammonia precursors at high temperature. The segregation was found to be independent of the cooling rates employed in this report, and to our knowledge has not been found nor reported for 2D h-BN growth so far, and thus provides an important direction for controlled growth of h-BN. This unique segregation behavior is a result of a combined effect of high diffusivity, small film thickness and the inability to achieve extremely high cooling rates in CVD systems. The resulting D-SS h-BN films exhibit excellent electrical insulating behavior with an optical bandgap of about 5.8 eV. Moreover, graphene-on-h-BN field effect transistors using the as-grown D-SS h-BN films show a mobility of about 6000 cm2 V-1 s-1 at room temperature.

Validation of a combined health literacy and numeracy instrument for patients with type 2 diabetes.

PubMed

Luo, Huabin; Patil, Shivajirao P; Wu, Qiang; Bell, Ronny A; Cummings, Doyle M; Adams, Alyssa D; Hambidge, Bertha; Craven, Kay; Gao, Fei

2018-05-20

This study aimed to validate a new consolidated measure of health literacy and numeracy (health literacy scale [HLS] plus the subjective numeracy scale [SNS]) in patients with type 2 diabetes (T2DM). A convenience sample (N = 102) of patients with T2DM was recruited from an academic family medicine center in the southeastern US between September-December 2017. Participants completed a questionnaire that included the composite HLS/SNS (22 questions) and a commonly used objective measure of health literacy-S-TOFHLA (40 questions). Internal reliability of the HLS/SNS was assessed using Cronbach's alpha. Criterion and construct validity was assessed against the S-TOFHLA. The composite HLS/SNS had good internal reliability (Cronbach's alpha = 0.83). A confirmatory factor analysis revealed there were four factors in the new instrument. Model fit indices showed good model-data fit (RMSEA = 0.08). The Spearman's rank order correlation coefficient between the HLS/SNS and the S-TOFHLA was 0.45 (p < 0.01). Our study suggests that the composite HLS/SNS is a reliable, valid instrument. Published by Elsevier B.V.

Effect of Hydrostatic Pressure on the Structural, Electronic and Optical Properties of SnS2 with a Cubic Structure: The DFT Approach

NASA Astrophysics Data System (ADS)

Bakhshayeshi, A.; Taghavi Mendi, R.; Majidiyan Sarmazdeh, M.

2018-02-01

Recently, a cubic structure of polymorphic SnS2 has been synthesized experimentally, which is stable at room temperature. In this paper, we calculated some structural, electronic and optical properties of the cubic SnS2 structure based on the full potential-linearized augmented plane waves method. We also studied the effect of hydrostatic pressure on the physical properties of the cubic SnS2 structure. Structural results show that the compressibility of the cubic SnS2 phase is greater than its trigonal phase and the compressibility decreases with increasing pressure. Investigations of the electronic properties indicate that pressure changes the density of states and the energy band gap increases with increasing pressure. The variation of energy band gap versus pressure is almost linear. We concluded that cubic SnS2 is a semiconductor with an indirect energy band gap, like its trigonal phase. The optical calculations revealed that the dielectric constant decreases with increasing pressure, and the width of the forbidden energy interval increases for electromagnetic wave propagation. Moreover, plasmonic energy and refractive index are changed with increasing pressure.

Electronic transport in NbSe₂ two-dimensional nanostructures: semiconducting characteristics and photoconductivity.

PubMed

Huang, Y H; Chen, R S; Zhang, J R; Huang, Y S

2015-12-07

The electronic transport properties of two-dimensional (2D) niobium diselenide (NbSe2) layer materials with two-hexagonal single-crystalline structures grown by chemical vapor transport were investigated. Those NbSe2 nanostructures isolated simply using mechanical exfoliation were found to exhibit lower conductivity and semiconducting properties, compared with their bulk metallic counterparts. Benefiting from lower dark conductivity, NbSe2 nanoflakes exhibit a remarkable photoresponse under different wavelengths and intensity excitations. The photocurrent responsivity and photoconductive gain can reach 3.8 A W(-1) and 300, respectively; these values are higher than those of graphene and MoS2 monolayers and are comparable with those of GaS and GaSe nanosheets. The presence of electron trap states at the surface was proposed as an explanation for the reduced dark conductivity and enhanced photoconductivity in the 2D NbSe2 nanostructures. This work identifies another possibility for the application of a metallic layer material as an optoelectronic component in addition to an ultrathin transparent conducting material.

Low-temperature atomic layer epitaxy of AlN ultrathin films by layer-by-layer, in-situ atomic layer annealing.

PubMed

Shih, Huan-Yu; Lee, Wei-Hao; Kao, Wei-Chung; Chuang, Yung-Chuan; Lin, Ray-Ming; Lin, Hsin-Chih; Shiojiri, Makoto; Chen, Miin-Jang

2017-01-03

Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amorphous phase to a single-crystalline epitaxial layer, at a low deposition temperature of 300 °C. The energy transferred from plasma not only provides the crystallization energy but also enhances the migration of adatoms and the removal of ligands, which significantly improve the crystallinity of the epitaxial layer. The X-ray diffraction reveals that the full width at half-maximum of the AlN (0002) rocking curve is only 144 arcsec in the AlN ultrathin epilayer with a thickness of only a few tens of nm. The high-resolution transmission electron microscopy also indicates the high-quality single-crystal hexagonal phase of the AlN epitaxial layer on the sapphire substrate. The result opens a window for further extension of the ALD applications from amorphous thin films to the high-quality low-temperature atomic layer epitaxy, which can be exploited in a variety of fields and applications in the near future.

Low-temperature atomic layer epitaxy of AlN ultrathin films by layer-by-layer, in-situ atomic layer annealing

PubMed Central

Shih, Huan-Yu; Lee, Wei-Hao; Kao, Wei-Chung; Chuang, Yung-Chuan; Lin, Ray-Ming; Lin, Hsin-Chih; Shiojiri, Makoto; Chen, Miin-Jang

2017-01-01

Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amorphous phase to a single-crystalline epitaxial layer, at a low deposition temperature of 300 °C. The energy transferred from plasma not only provides the crystallization energy but also enhances the migration of adatoms and the removal of ligands, which significantly improve the crystallinity of the epitaxial layer. The X-ray diffraction reveals that the full width at half-maximum of the AlN (0002) rocking curve is only 144 arcsec in the AlN ultrathin epilayer with a thickness of only a few tens of nm. The high-resolution transmission electron microscopy also indicates the high-quality single-crystal hexagonal phase of the AlN epitaxial layer on the sapphire substrate. The result opens a window for further extension of the ALD applications from amorphous thin films to the high-quality low-temperature atomic layer epitaxy, which can be exploited in a variety of fields and applications in the near future. PMID:28045075

77 FR 2674 - Airworthiness Directives; Glasflugel Gliders

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-19

... Models Standard Libelle-201B, Club Libelle 205, Mosquito, and Kestrel gliders. This proposed AD results... 205, all S/Ns (2) Kestrel, all S/Ns, except S/N 85, 110, and 125 (3) Mosquito, all S/Ns (4) Standard...

Tin Sulfide Phase Exploration: Dependence of Optoelectronic Properties on Microstructural Growth and Chemical Variations in Thin Film Material

NASA Astrophysics Data System (ADS)

Banai, Rona Elinor

Herzenbergite tin (II) monosulfide (alpha-SnS) is of growing interest as a photovoltaic material because of its interesting optoelectronic properties and Earth abundance. It has several stable phases due to the dual valency of tin. As a layered material, alpha-SnS has the ability to form varying microstructure with differing properties. For this dissertation, films were RF sputtered from a SnS and SnS2 target to produce films with varying microstructure. Growth of high energy phases includin beta-SnS and amorphous SnS2 were possible through sputtering. Films of mixed or strained phase resulted from both targets. Pure phase alpha-SnS was made by annealing amorphous SnS2 films. Microstructure was measured using grazing incidence XRD and field emission SEM. The impact of microstructure was seen for both optical and electronic properties. Films were evaluated using spectroscopic ellipsometry as well as unpolarized UV-Vis transmission and reflection measurements. Optical modeling of the films is sufficient for developing models corresponding to specific microstructure, enabling it to be an inexpensive tool for studying the material. Absorption coefficient and band gap were also derived for these films. Films deposited with the SnS target had resistivity values up to 20,000 O-cm. Annealing of amorphous films deposited from the SnS2 target resulted in alpha-SnS films with much lower resistivity (<50 O-cm) values. This method for producing alpha-SnS offered better control of the phase, microstructure and therefore optoelectronic properties. While SnS films made from either target were typically p-type, sputtering of the SnS2 target with substrate heating resulted in n-type SnSx of a potentially new phase similar to SnS2 but with a 2:3 tin-to-sulfur ratio. Resistivity of those films typically ranged from 1 to 40 O-cm. Both p- and n-type films made from the SnS2 target had high carrier concentration of 10 17 to 1020 cm-3, but films had low Hall mobility such that conductivity type was not determined. Titanium, molybdenum, and aluminum contacts were tested for Ohmic and Schottky behavior using transmission line measurements. The complexity of its microstructure and flexibility in formation of varying phase and altered phase presents challenges to its use as a PV absorber.

Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Xu-Qian; Lee, Jaesung; Feng, Philip X. -L.

Atomic layers of hexagonal boron nitride (h-BN) crystal are excellent candidates for structural materials as enabling ultrathin, two-dimensional (2D) nanoelectromechanical systems (NEMS) due to the outstanding mechanical properties and very wide bandgap (5.9 eV) of h-BN. In this work, we report the experimental demonstration of h-BN 2D nanomechanical resonators vibrating at high and very high frequencies (from ~ 5 to ~ 70 MHz), and investigations of the elastic properties of h-BN by measuring the multimode resonant behavior of these devices. First, we demonstrate a dry-transferred doubly clamped h-BN membrane with ~ 6.7 nm thickness, the thinnest h-BN resonator known tomore » date. In addition, we fabricate circular drumhead h-BN resonators with thicknesses ranging from ~ 9 to 292 nm, from which we measure up to eight resonance modes in the range of ~ 18 to 35 MHz. Combining measurements and modeling of the rich multimode resonances, we resolve h-BN’s elastic behavior, including the transition from membrane to disk regime, with built-in tension ranging from 0.02 to 2 N m -1. The Young’s modulus of h-BN is determined to be EY≈392 GPa from the measured resonances. The ultrasensitive measurements further reveal subtle structural characteristics and mechanical properties of the suspended h-BN diaphragms, including anisotropic built-in tension and bulging, thus suggesting guidelines on how these effects can be exploited for engineering multimode resonant functions in 2D NEMS transducers.« less

Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

DOE PAGES

Zheng, Xu-Qian; Lee, Jaesung; Feng, Philip X. -L.

2017-07-31

Atomic layers of hexagonal boron nitride (h-BN) crystal are excellent candidates for structural materials as enabling ultrathin, two-dimensional (2D) nanoelectromechanical systems (NEMS) due to the outstanding mechanical properties and very wide bandgap (5.9 eV) of h-BN. In this work, we report the experimental demonstration of h-BN 2D nanomechanical resonators vibrating at high and very high frequencies (from ~ 5 to ~ 70 MHz), and investigations of the elastic properties of h-BN by measuring the multimode resonant behavior of these devices. First, we demonstrate a dry-transferred doubly clamped h-BN membrane with ~ 6.7 nm thickness, the thinnest h-BN resonator known tomore » date. In addition, we fabricate circular drumhead h-BN resonators with thicknesses ranging from ~ 9 to 292 nm, from which we measure up to eight resonance modes in the range of ~ 18 to 35 MHz. Combining measurements and modeling of the rich multimode resonances, we resolve h-BN’s elastic behavior, including the transition from membrane to disk regime, with built-in tension ranging from 0.02 to 2 N m -1. The Young’s modulus of h-BN is determined to be EY≈392 GPa from the measured resonances. The ultrasensitive measurements further reveal subtle structural characteristics and mechanical properties of the suspended h-BN diaphragms, including anisotropic built-in tension and bulging, thus suggesting guidelines on how these effects can be exploited for engineering multimode resonant functions in 2D NEMS transducers.« less

Tuning the Schottky rectification in graphene-hexagonal boron nitride-molybdenum disulfide heterostructure.

PubMed

Liu, Biao; Zhao, Yu-Qing; Yu, Zhuo-Liang; Wang, Lin-Zhi; Cai, Meng-Qiu

2018-03-01

It was still a great challenge to design high performance of rectification characteristic for the rectifier diode. Lately, a new approach was proposed experimentally to tune the Schottky barrier height (SBH) by inserting an ultrathin insulated tunneling layer to form metal-insulator-semiconductor (MIS) heterostructures. However, the electronic properties touching off the high performance of these heterostructures and the possibility of designing more efficient applications for the rectifier diode were not presently clear. In this paper, the structural, electronic and interfacial properties of the novel MIS diode with the graphene/hexagonal boron nitride/monolayer molybdenum disulfide (GBM) heterostructure had been investigated by first-principle calculations. The calculated results showed that the intrinsic properties of graphene and MoS 2 were preserved due to the weak van der Waals contact. The height of interfacial Schottky barrier can be tuned by the different thickness of hBN layers. In addition, the GBM Schottky diode showed more excellent rectification characteristic than that of GM Schottky diode due to the interfacial band bending caused by the epitaxial electric field. Based on the electronic band structure, we analyzed the relationship between the electronic structure and the nature of the Schottky rectifier, and revealed the potential of utilizing GBM Schottky diode for the higher rectification characteristic devices. Copyright © 2017 Elsevier Inc. All rights reserved.

Surface plasmon resonance induced enhancement of photoluminescence and Raman line intensity in SnS quantum dot-Sn nanoparticle hybrid structure.

PubMed

Warrier, Anita R; Gandhimathi, R

2018-04-27

In this article, we report on enhancement in photoluminescence and Raman line intensity of SnS quantum dots embedded in a mesh of Sn nanostructures. SnS nanoparticles synthesized by homogenous precipitation method show strong quantum confinement with a band gap of ∼2.7 eV (blue shift of ∼1 eV compared to bulk SnS particles). The optical band gap of SnS quantum dots is controlled by varying the pH (∼0 to 2.25), ageing time (24 to 144 h) and molarity (0 to 2 M) of the precursors. These SnS nanoparticles are embedded in a mesh of Sn nanostructures which are synthesized from tin chloride by using sodium borohydride as reducing agent. The Sn nanostructures have a morphology dependent, tunable surface plasmon resonance (SPR), ranging from UV (∼295 nm) to visible region (∼400 nm) of the electromagnetic spectrum. In the SnS-Sn nanohybrids, the excitons are strongly coupled with plasmons leading to a shift in the excitonic binding energy (∼400 meV). The pure SnS quantum dots have a very weak photoluminescence peak at ∼560 nm and Raman shift of low intensity at 853.08 cm -1 , 1078.17 cm -1 , 1255.60 cm -1 , 1466.91 cm -1 . The coupling of SnS nanoparticles with Sn nanoparticles results in strong exciton-plasmon interactions leading to enhanced photoluminescence and Raman line intensity. The nanohybrids formed using Sn nanosheets whose SPR matches with absorption onset of the SnS nanoparticles shows an enhancement of ∼10 4 times higher than pure SnS nanoparticles. Thus, Sn nanosheet with surface plasmon resonance in visible region (400 nm) like Au and Ag is a promising material for surface enhanced Raman spectroscopy, plasmon assisted fluorescence imaging and for enhancing the emission intensity of semiconductors with weak emission intensity.

Surface plasmon resonance induced enhancement of photoluminescence and Raman line intensity in SnS quantum dot-Sn nanoparticle hybrid structure

NASA Astrophysics Data System (ADS)

Warrier, Anita R.; Gandhimathi, R.

2018-07-01

In this article, we report on enhancement in photoluminescence and Raman line intensity of SnS quantum dots embedded in a mesh of Sn nanostructures. SnS nanoparticles synthesized by homogenous precipitation method show strong quantum confinement with a band gap of ∼2.7 eV (blue shift of ∼1 eV compared to bulk SnS particles). The optical band gap of SnS quantum dots is controlled by varying the pH (∼0 to 2.25), ageing time (24 to 144 h) and molarity (0 to 2 M) of the precursors. These SnS nanoparticles are embedded in a mesh of Sn nanostructures which are synthesized from tin chloride by using sodium borohydride as reducing agent. The Sn nanostructures have a morphology dependent, tunable surface plasmon resonance (SPR), ranging from UV (∼295 nm) to visible region (∼400 nm) of the electromagnetic spectrum. In the SnS-Sn nanohybrids, the excitons are strongly coupled with plasmons leading to a shift in the excitonic binding energy (∼400 meV). The pure SnS quantum dots have a very weak photoluminescence peak at ∼560 nm and Raman shift of low intensity at 853.08 cm‑1, 1078.17 cm‑1, 1255.60 cm‑1, 1466.91 cm‑1. The coupling of SnS nanoparticles with Sn nanoparticles results in strong exciton-plasmon interactions leading to enhanced photoluminescence and Raman line intensity. The nanohybrids formed using Sn nanosheets whose SPR matches with absorption onset of the SnS nanoparticles shows an enhancement of ∼104 times higher than pure SnS nanoparticles. Thus, Sn nanosheet with surface plasmon resonance in visible region (400 nm) like Au and Ag is a promising material for surface enhanced Raman spectroscopy, plasmon assisted fluorescence imaging and for enhancing the emission intensity of semiconductors with weak emission intensity.

Ultrathin-shell boron nitride hollow spheres as sorbent for dispersive solid-phase extraction of polychlorinated biphenyls from environmental water samples.

PubMed

Fu, Meizhen; Xing, Hanzhu; Chen, Xiangfeng; Chen, Fan; Wu, Chi-Man Lawrence; Zhao, Rusong; Cheng, Chuange

2014-11-21

Boron nitride hollow spheres with ultrathin-shells were synthesized and used as sorbents for dispersive solid-phase extraction of aromatic pollutants at trace levels from environmental water samples. Polychlorinated biphenyls (PCBs) were selected as target compounds. Sample quantification and detection were performed by gas chromatography-tandem mass spectrometry. Extraction parameters influencing the extraction efficiency were optimized through response surface methodology using the Box-Behnken design. The proposed method achieved good linearity within the concentration range of 0.15-250 ng L(-1) PCBs, low limits of detection (0.04-0.09 ng L(-1), S/N=3:1), good repeatability of the extractions (relative standard deviation, <12%, n=6), and satisfactory recoveries between 84.9% and 101.0% under optimal conditions. Real environmental samples collected from rivers, local lakes, rain and spring waters were analyzed using the developed method. Results demonstrated that the hexagonal boron nitride-based material has significant potential as a sorbent for organic pollutant extraction from environmental water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties

PubMed Central

Asfandiyar; Wei, Tian-Ran; Li, Zhiliang; Sun, Fu-Hua; Pan, Yu; Wu, Chao-Feng; Farooq, Muhammad Umer; Tang, Huaichao; Li, Fu; Li, Bo; Li, Jing-Feng

2017-01-01

P–type SnS compound and SnS1−xSex solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS–pressurizing direction in the temperature range 323–823 Κ. SnS compound and SnS1−xSex solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m−1 K−1 at 823 K for the composition SnS0.5Se0.5. With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS0.2Se0.8 along the parallel direction. PMID:28240324

Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties.

PubMed

Asfandiyar; Wei, Tian-Ran; Li, Zhiliang; Sun, Fu-Hua; Pan, Yu; Wu, Chao-Feng; Farooq, Muhammad Umer; Tang, Huaichao; Li, Fu; Li, Bo; Li, Jing-Feng

2017-02-27

P-type SnS compound and SnS 1-x Se x solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS-pressurizing direction in the temperature range 323-823 Κ. SnS compound and SnS 1-x Se x solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m -1  K -1 at 823 K for the composition SnS 0.5 Se 0.5 . With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS 0.2 Se 0.8 along the parallel direction.

Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity

DOE PAGES

Cotlet, Mircea; Huang, Yuan Zang; Chen, Jia -Shiang; ...

2016-03-24

We report an improved photosensitivity in few-layer tin disulfide (SnS 2) field-effect transistors(FETs) following doping with CdSe/ZnS core/shell quantum dots(QDs). The hybrid QD-SnS 2 FET devices achieve more than 500% increase in the photocurrent response compared with the starting SnS 2-only FET device and a spectral responsivity reaching over 650 A/W at 400 nm wavelength. The negligible electrical conductance in a control QD-only FET device suggests that the energy transfer between QDs and SnS 2 is the main mechanism responsible for the sensitization effect, which is consistent with the strong spectral overlap between QDphotoluminescence and SnS 2 optical absorption asmore » well as the large nominal donor-acceptor interspacing between QD core and SnS 2. Furthermore, we also find enhanced charge carrier mobility in hybrid QD-SnS 2 FETs which we attribute to a reduced contact Schottky barrier width due to an elevated background charge carrier density.« less

SNS programming environment user's guide

NASA Technical Reports Server (NTRS)

Tennille, Geoffrey M.; Howser, Lona M.; Humes, D. Creig; Cronin, Catherine K.; Bowen, John T.; Drozdowski, Joseph M.; Utley, Judith A.; Flynn, Theresa M.; Austin, Brenda A.

1992-01-01

The computing environment is briefly described for the Supercomputing Network Subsystem (SNS) of the Central Scientific Computing Complex of NASA Langley. The major SNS computers are a CRAY-2, a CRAY Y-MP, a CONVEX C-210, and a CONVEX C-220. The software is described that is common to all of these computers, including: the UNIX operating system, computer graphics, networking utilities, mass storage, and mathematical libraries. Also described is file management, validation, SNS configuration, documentation, and customer services.

Fabrication of solar cells based on Cu2ZnSnS4 prepared from Cu2SnS3 synthesized using a novel chemical procedure

NASA Astrophysics Data System (ADS)

Correa, John M.; Becerra, Raúl A.; Ramírez, Asdrubal A.; Gordillo, Gerardo

2016-11-01

Solar cells based on kesterite-type Cu2ZnSnS4 (CZTS) thin films were fabricated using a chemical route to prepare the CZTS films, consisting in sequential deposition of Cu2SnS3 (CTS) and ZnS thin films followed by annealing at 550 °C in nitrogen atmosphere. The CTS compound was prepared in a one-step process using a novel chemical procedure consisting of simultaneous precipitation of Cu2S and SnS2 performed by diffusion membranes assisted CBD (chemical bath deposition) technique. Diffusion membranes were used to optimize the kinetic growth through a moderate control of release of metal ions into the work solution. As the conditions for the formation in one step of the Cu2SnS3 compound have not yet been reported in literature, special emphasis was put on finding the parameters that allow growing the Cu2SnS3 thin films by simultaneous precipitation of Cu2S and SnS2. For that, we propose a methodology that includes numerical solution of the equilibrium equations that were established through a study of the chemical equilibrium of the system SnCl2, Na3C6H5O7·2H2O, CuCl2 and Na2S2O3·5H2O. The formation of thin films of CTS and CZTS free of secondary phases grown with a stoichiometry close to that corresponding to the Cu2SnS3 and Cu2ZnSnS4 phases, was verified through measurements of X-ray diffraction (XRD) and Raman spectroscopy. Solar cell with an efficiency of 4.2%, short circuit current of 16.2 mA/cm2 and open-circuit voltage of 0.49 V was obtained.

Testing of SNS-032 in a Panel of Human Neuroblastoma Cell Lines with Acquired Resistance to a Broad Range of Drugs.

PubMed

Löschmann, Nadine; Michaelis, Martin; Rothweiler, Florian; Zehner, Richard; Cinatl, Jaroslav; Voges, Yvonne; Sharifi, Mohsen; Riecken, Kristoffer; Meyer, Jochen; von Deimling, Andreas; Fichtner, Iduna; Ghafourian, Taravat; Westermann, Frank; Cinatl, Jindrich

2013-12-01

Novel treatment options are needed for the successful therapy of patients with high-risk neuroblastoma. Here, we investigated the cyclin-dependent kinase (CDK) inhibitor SNS-032 in a panel of 109 neuroblastoma cell lines consisting of 19 parental cell lines and 90 sublines with acquired resistance to 14 different anticancer drugs. Seventy-three percent of the investigated neuroblastoma cell lines and all four investigated primary tumor samples displayed concentrations that reduce cell viability by 50% in the range of the therapeutic plasma levels reported for SNS-032 (<754 nM). Sixty-two percent of the cell lines and two of the primary samples displayed concentrations that reduce cell viability by 90% in this concentration range. SNS-032 also impaired the growth of the multidrug-resistant cisplatin-adapted UKF-NB-3 subline UKF-NB-3(r)CDDP(1000) in mice. ABCB1 expression (but not ABCG2 expression) conferred resistance to SNS-032. The antineuroblastoma effects of SNS-032 did not depend on functional p53. The antineuroblastoma mechanism of SNS-032 included CDK7 and CDK9 inhibition-mediated suppression of RNA synthesis and subsequent depletion of antiapoptotic proteins with a fast turnover rate including X-linked inhibitor of apoptosis (XIAP), myeloid cell leukemia sequence 1 (Mcl-1), baculoviral IAP repeat containing 2 (BIRC2; cIAP-1), and survivin. In conclusion, CDK7 and CDK9 represent promising drug targets and SNS-032 represents a potential treatment option for neuroblastoma including therapy-refractory cases.

Testing of SNS-032 in a Panel of Human Neuroblastoma Cell Lines with Acquired Resistance to a Broad Range of Drugs12

PubMed Central

Löschmann, Nadine; Michaelis, Martin; Rothweiler, Florian; Zehner, Richard; Cinatl, Jaroslav; Voges, Yvonne; Sharifi, Mohsen; Riecken, Kristoffer; Meyer, Jochen; von Deimling, Andreas; Fichtner, Iduna; Ghafourian, Taravat; Westermann, Frank; Cinatl, Jindrich

2013-01-01

Novel treatment options are needed for the successful therapy of patients with high-risk neuroblastoma. Here, we investigated the cyclin-dependent kinase (CDK) inhibitor SNS-032 in a panel of 109 neuroblastoma cell lines consisting of 19 parental cell lines and 90 sublines with acquired resistance to 14 different anticancer drugs. Seventy-three percent of the investigated neuroblastoma cell lines and all four investigated primary tumor samples displayed concentrations that reduce cell viability by 50% in the range of the therapeutic plasma levels reported for SNS-032 (<754 nM). Sixty-two percent of the cell lines and two of the primary samples displayed concentrations that reduce cell viability by 90% in this concentration range. SNS-032 also impaired the growth of the multidrug-resistant cisplatin-adapted UKF-NB-3 subline UKF-NB-3rCDDP1000 in mice. ABCB1 expression (but not ABCG2 expression) conferred resistance to SNS-032. The antineuroblastoma effects of SNS-032 did not depend on functional p53. The antineuroblastoma mechanism of SNS-032 included CDK7 and CDK9 inhibition-mediated suppression of RNA synthesis and subsequent depletion of antiapoptotic proteins with a fast turnover rate including X-linked inhibitor of apoptosis (XIAP), myeloid cell leukemia sequence 1 (Mcl-1), baculoviral IAP repeat containing 2 (BIRC2; cIAP-1), and survivin. In conclusion, CDK7 and CDK9 represent promising drug targets and SNS-032 represents a potential treatment option for neuroblastoma including therapy-refractory cases. PMID:24466371

Polarized neutron reflectivity study of perpendicular magnetic anisotropy in MgO/CoFeB/W thin films

NASA Astrophysics Data System (ADS)

Ambaye, Haile; Zhan, Xiao; Li, Shufa; Lauter, Valeria; Zhu, Tao

In this work we study the origin of PMA in MgO/CoFeB/W trilayer systems using polarized neutron reflectivity. Recently, the spin Hall effect in the heavy metals, such as Pt and Ta, has been of significant interest for highly efficient magnetization switching of the ultrathin ferromagnets sandwiched by such a heavy metal and an oxide, which can be used for spintronic based memory and logic devices. Most work has focused on heavy-metal/ferromagnet/oxide trilayer (HM/FM/MO) structures with perpendicular magnetic anisotropy (PMA), where the oxide layer plays the role of breaking inversion symmetry .No PMA was found in W/CoFeB/MgO films. An insertion of Hf layer in between the W and CoFeB layers, however, has been found to create a strong PMA. Roughness and formation of interface alloys by interdiffusion influences the extent of PMA. We intend to identify these influences using the depth sensitive technique of PNR. In our previous study, we have successfully performed polarized neutron reflectometry (PNR) measurements on the Ta/CoFeB/MgO/CoFeB/Ta thin film with MgO thickness of 1 nm. The PNR measurements were carried out using the BL-4A Magnetic Reflectometer at SNS. This work has been supported by National Basic Research Program of China (2012CB933102). Research at SNS was supported by the Office of BES, DOE.

Quantum size and electric field modulations on electronic structures of SnS2/BN hetero-multilayers

NASA Astrophysics Data System (ADS)

Xia, Congxin; Zhang, Qian; Xiao, Wenbo; Du, Juan; Li, Xueping; Li, Jingbo

2018-05-01

Through first-principles calculations, we study the stability, band structures, band alignment, and interlayer charge transfer of SnS2/BN hetero-multilayers, considering quantum size and electric field effects. We find that SnS2/BN hetero-multilayers possess the characteristics of direct band structures and type-II band alignment. Moreover, increasing the BN layer number can decrease the band gap value and work function. Additionally, type-II can be tuned to type-I band alignment in the presence of an electric field. These results indicate that the SnS2/BN system is different from that of other BN-based hybrid materials, such as MoS2/BN with type-I band alignment, which is promising for optoelectronic device applications.

Combinatorial development of Cu2SnS3 as an earth abundant photovoltaic absorber

NASA Astrophysics Data System (ADS)

Baranowski, Lauryn L.

The development of high efficiency, earth abundant photovoltaic absorbers is critical if photovoltaics are to be implemented on the TW scale. Although traditional thin films absorbers such as Cu(In,Ga)Se2 and CdTe have achieved over 20% device efficiencies, the ultimately scalability of these devices may be limited by elemental scarcity and toxicity issues. To date, the most successful earth abundant thin film absorber is Cu2ZnSn(S,Se) 4, which has achieved 12.6% efficiency as of 2014. However, chemical complexity and disorder issues with this material have made the path to higher efficiency CZTSSe devices unclear. As a result, many researchers are now exploring alternative earth abundant absorber materials. In this thesis, we apply our "rapid development" methodology to the exploration of alternative photovoltaic absorbers. The rapid development (RD) methodology, consisting of exploration, research, and development stages, uses complementary theory and experiment to assess candidate materials and down-select in each stage. The overall result is that, in the time span of ~2-3 years, we are able to rapidly go from tens of possible absorber materials to 1-2 working PV device prototypes. Here, we demonstrate the RD approach as applied to the Cu-Sn-S system. We begin our investigation of the Cu-Sn-S system by evaluating the thermodynamic stability, electrical transport, electronic structure, and optical and defect properties of candidate materials using complementary theory and experiment. We find that Cu2SnS3 is the most promising absorber candidate because of its strong optical absorption, tunable doping, and wide stability range. Our other candidate compounds suffer from serious flaws that preclude them from being successful photovoltaic absorbers, including too high experimental conductivity (Cu4SnS4), or poor hole transport and low absorption coefficient (Cu4Sn7S16). Next, we investigate the doping and defect physics of Cu2SnS 3. We identify the origins of the changes in doping in sputtered cubic Cu2SnS3 thin films using combinatorial experiments and first-principles theory. High S chemical potential during deposition decreases the enthalpy of formation of Cu vacancies, which are the dominant acceptor defect in Cu2SnS3. Unexpectedly, under Cu-rich conditions, alloying with an isostructural (cubic) metallic Cu3SnS4 phase occurs, causing high levels of p-type doping. Both of these effects lead to undesirably high electrical conductivity, thus Cu2SnS 3 films must be grown both S- and Cu-poor in order to achieve moderate hole concentrations. To understand the effects of structural disorder on the transport properties in Cu2SnS3 we develop synthetic techniques to control this disorder, and observe improvements in the majority carrier (hole) transport. However, when the minority carrier (electron) transport was investigated, minimal differences were observed between the ordered and disordered Cu 2SnS3. By combining these results with first-principles and Monte Carlo theoretical calculations, we are able to conclude that even ostensibly "ordered" Cu2SnS3 displays minority carrier transport properties corresponding to the disordered structure. The presence of extended planar defects in all samples, observed in TEM imaging, suggests that disorder is present even when it is not detectable using traditional structural characterization methods. Lastly, we attempt to integrate our Cu2SnS3 films into photovoltaic devices, which requires translating our growth techniques to conductive substrates. We survey a wide range of possible conductive substrates, but are not able to find a suitable back contact for Cu2SnS 3 device integration, due to issues such as secondary phase formation and delamination. From a survey of successful Cu2SnS3 device literature, we are able to conclude that the issue may lie with our binary sputtering method in which the ternary compound formation and the film growth occur simultaneously. At the conclusion of this study, we eliminated Cu2SnS as an absorber candidate for future development. However, the two main issues we encountered (eliminating structural disorder and difficulty growing on conductive back contacts) may both be related to our binary sputtering technique. We expect that interest in Cu2SnS3-based photovoltaics will continue to grow, and that further scientific understanding may shed light on our particular difficulties. In the future, the RD methodology has the potential to greatly accelerate the discovery and development of non-traditional thin film absorbers, and may enable high impact material breakthroughs.

Future Muon Source Possibilities at the SNS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Travis J.; MacDougall, Prof. Gregory J.

2017-06-01

The workshop “Future Muon Source Possibilities at the SNS” was held September 1-2, 2016 at Oak Ridge National Laboratory. The workshop aimed to examine the technical feasibility and scientific need to construct a μSR and/or β-NMR facility at the SNS. During the course of the workshop it became evident that recently developed technology could enable the development of a world leading pulsed muon source at SNS, without impacting the neutron science missions of the SNS. The details are discussed below.

Enhancement of photoelectrochemical activity of SnS thin-film photoelectrodes using TiO2, Nb2O5, and Ta2O5 metal oxide layers

NASA Astrophysics Data System (ADS)

Vequizo, Junie Jhon M.; Yokoyama, Masanori; Ichimura, Masaya; Yamakata, Akira

2016-06-01

Tin sulfide (SnS) fine photoelectrodes fabricated by three-step pulsed electrodeposition were active for H2 evolution. The incident-photon-conversion-efficiency increases from 900 nm and offers a good fit with the absorption spectrum. The activity was enhanced by 3.4, 3.0, and 1.8 times compared to bare SnS by loading Nb2O5, TiO2, and Ta2O5, respectively. Nb2O5 was most efficient because its conduction band is low enough to facilitate effective electron transfer from SnS; it also has sufficiently high potential for H2 evolution. The overall activity is determined by the competitive interfacial electron transfer between SnS/metal-oxide and metal-oxide/water. Therefore, constructing appropriate heterojunctions is necessary for further improving photoelectrochemical systems.

Fabrication of 2D SnS2/g-C3N4 heterojunction with enhanced H2 evolution during photocatalytic water splitting.

PubMed

Liu, Enzhou; Chen, Jibing; Ma, Yongning; Feng, Juan; Jia, Jia; Fan, Jun; Hu, Xiaoyun

2018-08-15

In this work, the 2D SnS 2 /g-C 3 N 4 heterojunctions were successfully prepared by heating the homogeneous dispersion of SnS 2 nanosheets and g-C 3 N 4 nanosheets using a microwave muffle. SEM, TEM and HRTEM images indicated that the SnS 2 nanosheets were loaded on the surface of the g-C 3 N 4 nanosheets. The UV-vis spectra show that the absorption intensity of the as-prepared samples was increased and the absorption range was also extended from 420 nm to approximately 600 nm. The H 2 production rate over 5 wt% SnS 2 /g-C 3 N 4 can reach 972.6 μmol·h -1 ·g -1 under visible light irradiation (λ > 420 nm) using TEOA as the sacrifice agent and Pt as the electron trap, which is 2.9 and 25.6 times higher than those of the pristine g-C 3 N 4 and SnS 2 , respectively. According to the obtained PL spectra, photocurrent and EIS spectra, the enhanced performance for H 2 generation over the heterojunctions is primarily ascribed to the rapid charge transfer arising from the suitable band gap positions leading to an improved photocatalytic performance. The recycling experiments indicated that the as-prepared composites exhibit good stability in H 2 production. Additionally, a possible enhanced mechanism for H 2 evolution was deduced based on the results obtained by various characterization techniques. Copyright © 2018 Elsevier Inc. All rights reserved.

Electrochemical synthesis of nanostructured Se-doped SnS: Effect of Se-dopant on surface characterizations

NASA Astrophysics Data System (ADS)

Kafashan, Hosein; Azizieh, Mahdi; Balak, Zohre

2017-07-01

SnS1-xSex nanostructures with different Se-dopant concentrations were deposited on fluorine doped tin oxide (FTO) substrate through cathodic electrodeposition technique. The pH, temperature, applied potential (E), and deposition time remained were 2.1, 60 °C, -1 V, and 30 min, respectively. SnS1-xSex nanostructures were characterized using X-ray diffraction (XRD), field emission scanning electron microcopy (FESEM), energy dispersive X-ray spectroscopy (EDX), room temperature photoluminescence (PL), and UV-vis spectroscopy. The XRD patterns revealed that the SnS1-xSex nanostructures were polycrystalline with orthorhombic structure. FESEM showed various kinds of morphologies in SnS1-xSex nanostructures due to Se-doping. PL and UV-vis spectroscopy were used to evaluate the optical properties of SnS1-xSex thin films. The PL spectra of SnS1-xSex nanostructures displayed four emission peaks, those are a blue, a green, an orange, and a red emission. UV-vis spectra showed that the optical band gap energy (Eg) of SnS1-xSex nanostructures varied between 1.22-1.65 eV, due to Se-doping.

Long term safety of sacral nerve modulation in medicare beneficiaries.

PubMed

Chughtai, Bilal; Sedrakyan, Art; Isaacs, Abby; Lee, Richard; Te, Alexis; Kaplan, Steven

2015-09-01

Sacral nerve stimulation (SNS) is FDA approved as second-line therapy for both urinary and bowel control. However, there is limited evidence regarding long term safety. We determined adverse events associated with SNS among Medicare beneficiaries. We used the 5% national random sample of Medicare claims for 2001-2011 to identify patients. Patients who underwent SNS implantation were identified with Current Procedure Terminology (CPT-4) codes. We determined safety of SNS using analysis of complication occurrences on day of surgery and during 5 years following initial procedure. SAS v9.3 statistical package was used. One thousand four hundred seventy-four patients underwent treatment with SNS in the 5% national sample of Medicare patients within the time period. Representative of real-world patients undergoing SNS surgery, comorbidities included hypertension (69.3%), diabetes (29.4%), chronic pulmonary disease (25.5%), hypothyroidism (25.2%), and depression (22.7%). Few complications occurred on day of surgery. At 90 days, 3.2% of patients had bowel complications, 2.0% urological, 9.4% infectious, and 1.5% stroke. Overall, bowel, neurological health event occurrences were consistent with prior year rates, while infectious events decreased. Of 206 patients who were followed for at least 5 years, 17.3% had devices removed and 11.3% replaced, with 26.1% having at least one of those, leaving 73.9% with original devices. Urological, infectious, and bowel complication occurrences were low after SNS among Medicare beneficiaries with multiple comorbidities. There were infrequent serious complications like hemorrhage and stroke postoperatively. Although SNS appears safe in this high-risk population, a comprehensive registry will ensure continuous safety. © 2014 Wiley Periodicals, Inc.

It is all about being popular: the effects of need for popularity on social network site use.

PubMed

Utz, Sonja; Tanis, Martin; Vermeulen, Ivar

2012-01-01

Prior research on predictors of social network site (SNS) use has mainly focused on the Big Five, narcissism, and self-esteem. Results have been inconsistent, and variance explained was rather low. Need for popularity (NfP) might be a better predictor of SNS use, because SNSs are ideal venues for people with a high NfP. Study 1 tested NfP, self-esteem, need to belong, entitlement, and vanity as predictors for a range of SNS behaviors; Study 2 replaced entitlement and vanity with narcissism and added the Big Five as predictors. SNS behaviors assessed were grooming, strategic self-presentation, profile enhancement, disclosure of feelings, routine use of SNS, and number of friends. Results showed that NfP was the strongest and most consistent predictor of SNS behaviors. This pattern indicates that NfP plays an important role in SNSs.

Electrochemical growth of SnS thin film: application to the photocatalytic degradation of rhodamine B under visible light

NASA Astrophysics Data System (ADS)

Kabouche, S.; Louafi, Y.; Bellal, B.; Trari, M.

2017-08-01

A facile and template-free wet electrochemical technique was used to deposit SnS on tin substrate. Longer time (>40 min) is required for the formation of the chalcogenide thin films and the potential must be carefully controlled to come out with a rough chemical identification of sulfide deposited at low potential scan. The deposition potential is selected from the cyclic voltammetry to preclude the oxidation of SnS to SnS2. The SnS films are uniform and well adhered to the substrate. They were characterized by X-ray diffraction, UV-Vis spectroscopy and electrochemical impedance spectroscopy (EIS). SnS crystallizes in an orthorhombic symmetry (SG: Pnma) and a crystallite size of 42 nm was obtained. The Mott-Schottky plot exhibited a linear behavior with a negative slope, characteristic of p-type conductivity. Holes density of 9.75 × 1020 cm-3, a flat band potential of 0.56 V SCE and a depletion width of 38 nm were determined. The valence band was located at (-5.41 eV/0.66 V) and derives mainly from S 2-: 3 p while the conduction band (3.8 eV/-0.95 V) was primarily made up of Sn2+: 5 p orbital. The EIS spectra measured over the frequency range (3 × 10-3-105 Hz) revealed mainly a bulk contribution. On application, rhodamine B was successfully oxidized on SnS films, 38% of the initial concentration (10 mg L-1) disappeared after 4 h of exposure to solar light (90 mW cm-2).

Characteristics and outcomes of secondary nodules identified on initial computed tomography scan for patients undergoing resection for primary non-small cell lung cancer.

PubMed

Stiles, Brendon M; Schulster, Michael; Nasar, Abu; Paul, Subroto; Lee, Paul C; Port, Jeffrey L; Altorki, Nasser K

2015-01-01

We sought to define the prevalence, malignancy rate, and outcome of secondary nodules (SNs) detected on computed tomography (CT) scan for patients undergoing resection for primary non-small cell lung cancer (NSCLC). In consecutive patients with NSCLC, we reviewed all CT scan reports obtained at diagnosis of the dominant tumor for description of SNs. When resected, pathology was reviewed. Serial CT reports for 2 years postoperatively were evaluated to follow SNs not resected. Among 155 patients, 88 (57%) were found to have SNs. A total of 137 SNs were evaluated (median size, 0.5 cm). Thirty-two nodules were resected at primary resection. Nineteen (61%) resected nodules were benign, whereas 13 (39%) were malignant (8 synchronous primary tumors and 5 lobar metastases). A total of 105 unresected nodules were followed by CT. Of these, 32 (30%) resolved completely, 20 (19%) shrunk, and 28 (27%) were stable, whereas 11 (11%) were lost to follow-up. Fourteen SNs (13%) grew, of which 5 were found to be malignant, each a new primary. Overall 5-year survival was not different between patients with or without SNs (67% vs 64%; P = .88). The prevalence of SNs on CT scan in patients undergoing resection for primary NSCLC is high. Only a low proportion of SNs are ever found to be malignant, predominantly those on the ipsilateral side as the dominant tumor. The presence of SNs has no effect on survival. Patients with SNs, if otherwise appropriately staged, should not be denied surgical therapy. Copyright © 2015. Published by Elsevier Inc.

Online social networking in adolescence: patterns of use in six European countries and links with psychosocial functioning.

PubMed

Tsitsika, Artemis K; Tzavela, Eleni C; Janikian, Mari; Ólafsson, Kjartan; Iordache, Andreea; Schoenmakers, Tim Michaël; Tzavara, Chara; Richardson, Clive

2014-07-01

Online communication tools, such as social networking sites (SNS), have been comprehensively embraced by adolescents and have become a dominant daily social practice. Recognizing SNS as a key context of adolescent development, this study aimed to investigate associations between heavier SNS use, and adolescent competencies and internalizing problems. Data was collected in six European countries: Greece, Spain, Poland, the Netherlands, Romania, and Iceland. Participants were 10,930 adolescents aged 14-17 years (F/M: 5,719/5,211; mean age 15.8 ± .7 years); 62.3% were aged 14-15.9 years and 37.7% were aged 16-17.9 years. Participants reported on their use of online communication tools, and their general competencies and internalizing problems (Youth Self Report). SNS are both ubiquitous--used by 70% of adolescents--and engaging, given that 40% of users spend 2 or more hours daily on SNS (labeled heavier SNS use). Heavier SNS use was associated with more internalizing problems, and the relation was consistently more pronounced among younger adolescents. Moreover, heavier SNS use was associated with lower academic performance and lower activities scores, especially for younger adolescents. In contrast, among older adolescents heavier SNS use was positively associated with offline social competence. Although heavier SNS use is associated with higher social competence for older adolescents, it is also associated with increased internalizing problems and diminished competencies in academics and activities, especially for younger adolescents. Age, capturing developmental differences in social and regulatory skills, appears to moderate the effects of heavier SNS use on adolescent functioning. Copyright © 2014 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Partially Oxidized SnS2 Atomic Layers Achieving Efficient Visible-Light-Driven CO2 Reduction.

PubMed

Jiao, Xingchen; Li, Xiaodong; Jin, Xiuyu; Sun, Yongfu; Xu, Jiaqi; Liang, Liang; Ju, Huanxin; Zhu, Junfa; Pan, Yang; Yan, Wensheng; Lin, Yue; Xie, Yi

2017-12-13

Unraveling the role of surface oxide on affecting its native metal disulfide's CO 2 photoreduction remains a grand challenge. Herein, we initially construct metal disulfide atomic layers and hence deliberately create oxidized domains on their surfaces. As an example, SnS 2 atomic layers with different oxidation degrees are successfully synthesized. In situ Fourier transform infrared spectroscopy spectra disclose the COOH* radical is the main intermediate, whereas density-functional-theory calculations reveal the COOH* formation is the rate-limiting step. The locally oxidized domains could serve as the highly catalytically active sites, which not only benefit for charge-carrier separation kinetics, verified by surface photovoltage spectra, but also result in electron localization on Sn atoms near the O atoms, thus lowering the activation energy barrier through stabilizing the COOH* intermediates. As a result, the mildly oxidized SnS 2 atomic layers exhibit the carbon monoxide formation rate of 12.28 μmol g -1 h -1 , roughly 2.3 and 2.6 times higher than those of the poorly oxidized SnS 2 atomic layers and the SnS 2 atomic layers under visible-light illumination. This work uncovers atomic-level insights into the correlation between oxidized sulfides and CO 2 reduction property, paving a new way for obtaining high-efficiency CO 2 photoreduction performances.

Predictors of Mobile Phone and Social Networking Site Dependency in Adulthood.

PubMed

Burnell, Kaitlyn; Kuther, Tara L

2016-10-01

The present study explored social and psychological predictors of social networking site (SNS) and mobile phone dependency in a sample of emerging adults (ages 18-25, n = 159, M = 21.87, SD = 2.08) and young adults (ages 26-40, n = 97, M = 31.21, SD = 4.11). Path analysis revealed that SNS dependency mediated the relationship of social comparison, SNS support, and impulsivity on mobile phone dependency. Impulsivity also showed direct links to mobile phone dependency. The present findings suggest that individuals with a strong orientation toward social comparison, who perceive a strong sense of support through SNS networks, or who show difficulty with self-regulation may be at risk for SNS and mobile phone dependency.

KF addition to Cu2SnS3 thin films prepared by sulfurization process

NASA Astrophysics Data System (ADS)

Nakashima, Mitsuki; Fujimoto, Junya; Yamaguchi, Toshiyuki; Sasano, Junji; Izaki, Masanobu

2017-04-01

Cu2SnS3 thin films were fabricated by sulfurization with KF addition and applied to photovoltaic devices. Two methods, two-stage annealing and the use of four-layer precursors, were employed, and the quantity of NaF and KF and the annealing temperature were changed. By electron probe microanalysis (EPMA), the Cu/Sn mole ratio was found to range from 0.81 to 1.51. The X-ray diffraction (XRD) patterns and Raman spectra indicated that the fabricated thin films had a monoclinic Cu2SnS3 structure. The Cu2SnS3 thin films fabricated by two-stage annealing had a close-packed structure and a pinhole-free surface morphology. The best solar cell in this study showed V oc of 293 mV, which surpassed the previously reported value.

Electronic and magnetic properties of SnS2 monolayer doped with non-magnetic elements

NASA Astrophysics Data System (ADS)

Xiao, Wen-Zhi; Xiao, Gang; Rong, Qing-Yan; Wang, Ling-Ling

2018-05-01

We performed a systematic study of the electronic structures and magnetic properties of SnS2 monolayer doped with non-magnetic elements in groups IA, IIA and IIIA based on the first-principles methods. The doped systems exhibit half-metallic and metallic natures depending on the doping elements. The formation of magnetic moment is attributable to the cooperative effect of the Hund's rule coupling and hole concentration. The spin polarization can be stabilized and enhanced through confining the delocalized impurity states by biaxial tensile strain in hole-doped SnS2 monolayer. Both the double-exchange and p-p exchange mechanisms are simultaneously responsible for the ferromagnetic ground state in those hole-doped materials. Our results demonstrate that spin polarization can be induced and controlled in SnS2 monolayers by non-magnetic doping and tensile strain.

Occurrence of Multiple Subsequent Neoplasms in Long-Term Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study

PubMed Central

Armstrong, Gregory T.; Liu, Wei; Leisenring, Wendy; Yasui, Yutaka; Hammond, Sue; Bhatia, Smita; Neglia, Joseph P.; Stovall, Marilyn; Srivastava, Deokumar; Robison, Leslie L.

2011-01-01

Purpose Childhood cancer survivors experience an increased incidence of subsequent neoplasms (SNs). Those surviving the first SN (SN1) remain at risk to develop multiple SNs. Because SNs are a common cause of late morbidity and mortality, characterization of rates of multiple SNs is needed. Patients and Methods In a total of 14,358 5-year survivors of childhood cancer diagnosed between 1970 and 1986, analyses were carried out among 1,382 survivors with an SN1. Cumulative incidence of second subsequent neoplasm (SN2), either malignant or benign, was calculated. Results A total of 1,382 survivors (9.6%) developed SN1, of whom 386 (27.9%) developed SN2. Of those with SN2, 153 (39.6%) developed more than two SNs. Cumulative incidence of SN2 was 46.9% (95% CI, 41.6% to 52.2%) at 20 years after SN1. The cumulative incidence of SN2 among radiation-exposed survivors was 41.3% (95% CI, 37.2% to 45.4%) at 15 years compared with 25.7% (95% CI, 16.5% to 34.9%) for those not treated with radiation. Radiation-exposed survivors who developed an SN1 of nonmelanoma skin cancer (NMSC) had a cumulative incidence of subsequent malignant neoplasm (SMN; ie, malignancies excluding NMSC) of 20.3% (95% CI, 13.0% to 27.6%) at 15 years compared with only 10.7% (95% CI, 7.2% to 14.2%) for those who were exposed to radiation and whose SN1 was an invasive SMN (excluding NMSC). Conclusion Multiple SNs are common among aging survivors of childhood cancer. SN1 of NMSC identifies a population at high risk for invasive SMN. Survivors not exposed to radiation who develop multiple SNs represent a population of interest for studying genetic susceptibility to neoplasia. PMID:21709189

Anisotropic thermoelectric properties of layered compounds in SnX2 (X = S, Se): a promising thermoelectric material.

PubMed

Sun, Bao-Zhen; Ma, Zuju; He, Chao; Wu, Kechen

2015-11-28

Thermoelectrics interconvert heat to electricity and are of great interest in waste heat recovery, solid-state cooling and so on. Here we assessed the potential of SnS2 and SnSe2 as thermoelectric materials at the temperature gradient from 300 to 800 K. Reflecting the crystal structure, the transport coefficients are highly anisotropic between a and c directions, in particular for the electrical conductivity. The preferred direction for both materials is the a direction in TE application. Most strikingly, when 800 K is reached, SnS2 can show a peak power factor (PF) of 15.50 μW cm(-1) K(-2) along the a direction, while a relatively low value (11.72 μW cm(-1) K(-2)) is obtained in the same direction of SnSe2. These values are comparable to those observed in thermoelectrics such as SnSe and SnS. At 300 K, the minimum lattice thermal conductivity (κmin) along the a direction is estimated to be about 0.67 and 0.55 W m(-1) K(-1) for SnS2 and SnSe2, respectively, even lower than the measured lattice thermal conductivity of Bi2Te3 (1.28 W m(-1) K(-1) at 300 K). The reasonable PF and κmin suggest that both SnS2 and SnSe2 are potential thermoelectric materials. Indeed, the estimated peak ZT can approach 0.88 for SnSe2 and a higher value of 0.96 for SnS2 along the a direction at a carrier concentration of 1.94 × 10(19) (SnSe2) vs. 2.87 × 10(19) cm(-3) (SnS2). The best ZT values in SnX2 (X = S, Se) are comparable to that in Bi2Te3 (0.8), a typical thermoelectric material. We hope that this theoretical investigation will provide useful information for further experimental and theoretical studies on optimizing the thermoelectric properties of SnX2 materials.

Excessive Time on Social Networking Sites and Disordered Eating Behaviors Among Undergraduate Students: Appearance and Weight Esteem as Mediating Pathways.

PubMed

Murray, Marisa; Maras, Danijela; Goldfield, Gary S

2016-12-01

Social networking sites (SNS) are a popular form of communication among undergraduate students. Body image concerns and disordered eating behaviors are also quite prevalent among this population. Maladaptive use of SNS has been associated with disordered eating behaviors; however, the mechanisms remain unclear. The present study examined if body image concerns (e.g., appearance and weight esteem) mediate the relationship between excessive time spent on SNS and disordered eating behaviors (restrained and emotional eating). The sample included 383 (70.2 percent female) undergraduate students (mean age = 23.08 years, standard deviation = 3.09) who completed self-report questionnaires related to SNS engagement, body image, disordered eating behaviors, and demographics. Parallel multiple mediation and moderated mediation analyses revealed that lower weight and appearance esteem mediated the relationship between excessive time on SNS and restrained eating for males and females, whereas appearance esteem mediated the relationship between excessive time on SNS and emotional eating for females only. The study adds to the literature by highlighting mediational pathways and gender differences. Intervention research is needed to determine if teaching undergraduate students more adaptive ways of using SNS or reducing exposure to SNS reduces body dissatisfaction and disordered eating in this high-risk population.

Taking Stress Response out of the Box: Stability, Discontinuity, and Temperament Effects on HPA and SNS across Social Stressors in Mother-Infant Dyads

ERIC Educational Resources Information Center

Laurent, Heidemarie K.; Ablow, Jennifer C.; Measelle, Jeffrey

2012-01-01

This study investigated continuity and stability of hypothalamic-pituitary-adrenal (HPA) and sympathetic nervous system (SNS) response measures in mother-infant dyads across 2 different types of social stress sessions. Synchrony of response trajectories across systems (SNS-HPA coordination) and partners (mother-infant attunement) was addressed, as…

2-Aminobenzimidazoles as potent Aurora kinase inhibitors.

PubMed

Zhong, Min; Bui, Minna; Shen, Wang; Baskaran, Subramanian; Allen, Darin A; Elling, Robert A; Flanagan, W Michael; Fung, Amy D; Hanan, Emily J; Harris, Shannon O; Heumann, Stacey A; Hoch, Ute; Ivy, Sheryl N; Jacobs, Jeffrey W; Lam, Stuart; Lee, Heman; McDowell, Robert S; Oslob, Johan D; Purkey, Hans E; Romanowski, Michael J; Silverman, Jeffrey A; Tangonan, Bradley T; Taverna, Pietro; Yang, Wenjin; Yoburn, Josh C; Yu, Chul H; Zimmerman, Kristin M; O'Brien, Tom; Lew, Willard

2009-09-01

This Letter describes the discovery and key structure-activity relationship (SAR) of a series of 2-aminobenzimidazoles as potent Aurora kinase inhibitors. 2-Aminobenzimidazole serves as a bioisostere of the biaryl urea residue of SNS-314 (1c), which is a potent Aurora kinase inhibitor and entered clinical testing in patients with solid tumors. Compared to SNS-314, this series of compounds offers better aqueous solubility while retaining comparable in vitro potency in biochemical and cell-based assays; in particular, 6m has also demonstrated a comparable mouse iv PK profile to SNS-314.

Propofol-induced increase in vascular capacitance is due to inhibition of sympathetic vasoconstrictive activity.

PubMed

Hoka, S; Yamaura, K; Takenaka, T; Takahashi, S

1998-12-01

Venodilation is thought to be one of the mechanisms underlying propofol-induced hypotension. The purpose of this study is to test two hypotheses: (1) propofol increases systemic vascular capacitance, and (2) the capacitance change produced by propofol is a result of an inhibition of sympathetic vasoconstrictor activity. In 33 Wistar rats previously anesthetized with urethane and ketamine, vascular capacitance was examined before and after propofol infusion by measuring mean circulatory filling pressure (Pmcf). The Pmcf was measured during a brief period of circulatory arrest produced by inflating an indwelling balloon in the right atrium. Rats were assigned into four groups: an intact group, a sympathetic nervous system (SNS)-block group produced by hexamethonium infusion, a SNS-block + noradrenaline (NA) group, and a hypovolemic group. The Pmcf was measured at a control state and 2 min after a bolus administration of 2, 10, and 20 mg/kg of propofol. The mean arterial pressure (MAP) was decreased by propofol dose-dependently in intact, hypovolemic, and SNS-block groups, but the decrease in MAP was less in the SNS-block group (-25%) than in the intact (-50%) and hypovolemic (-61%) groups. In the SNS-block + NA group, MAP decreased only at 20 mg/kg of propofol (-18%). The Pmcf decreased in intact and hypovolemic groups in a dose-dependent fashion but was unchanged in the SNS-block and SNS-block + NA groups. The results have provided two principal findings: (1) propofol decreases Pmcf dose-dependently, and (2) the decrease in Pmcf by propofol is elicited only when the sympathetic nervous system is intact, suggesting that propofol increases systemic vascular capacitance as a result of an inhibition of sympathetic nervous system.

"Facebook depression?" social networking site use and depression in older adolescents.

PubMed

Jelenchick, Lauren A; Eickhoff, Jens C; Moreno, Megan A

2013-01-01

To evaluate the association between social networking site (SNS) use and depression in older adolescents using an experience sample method (ESM) approach. Older adolescent university students completed an online survey containing the Patient Health Questionnaire-9 depression screen (PHQ) and a week-long ESM data collection period to assess SNS use. Participants (N = 190) included in the study were 58% female and 91% Caucasian. The mean age was 18.9 years (standard deviation = .8). Most used SNSs for either <30 minutes (n = 100, 53%) or between 30 minutes and 2 hours (n = 74, 39%); a minority of participants reported daily use of SNS >2 hours (n = 16, 8%). The mean PHQ score was 5.4 (standard deviation = 4.2). No associations were seen between SNS use and either any depression (p = .519) or moderate to severe depression (p = .470). We did not find evidence supporting a relationship between SNS use and clinical depression. Counseling patients or parents regarding the risk of "Facebook Depression" may be premature. Copyright © 2013 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Effect of annealing atmosphere on properties of Cu2ZnSn(S,Se)4 thin films

NASA Astrophysics Data System (ADS)

Xue, Yuming; Yu, Bingbing; Li, Wei; Feng, Shaojun; Wang, Yukun; Huang, Shengming; Zhang, Chao; Qiao, Zaixiang

2017-12-01

Earth-abundant Cu2ZnSn(S,Se)4(CZTSSe) thin film photovoltaic absorber layers were fabricated by co-evaporated Cu, ZnS, SnS and Se sources in a vacuum chamber followed by annealing at tubular furnace for 30 min at 550 °C. In this paper, we investigated the metal elements with stoichiometric ratio film to study the effect of annealing conditions of Se, SnS + Se, S and SnS + S atmosphere on the structure, surface morphological, optical and electrical properties of Cu2ZnSn(S,Se)4 thin films respectively. These films were characterized by Inductively Coupled Plasma-Mass Spectrometer, scanning electron microscopy, X-ray diffraction to investigate the composition, morphological and crystal structural properties. The grain size of samples were found to increase after annealing. XRD patterns confirmed the formation of pure polycrystalline CZTSSe thin films at S atmosphere, the optical band gaps are 1.02, 1.05, 1.23, 1.35 eV for Se, SnS + Se, SnS + S and S atmosphere respectively.

System and method for embedding emotion in logic systems

NASA Technical Reports Server (NTRS)

Curtis, Steven A. (Inventor)

2012-01-01

A system, method, and computer readable-media for creating a stable synthetic neural system. The method includes training an intellectual choice-driven synthetic neural system (SNS), training an emotional rule-driven SNS by generating emotions from rules, incorporating the rule-driven SNS into the choice-driven SNS through an evolvable interface, and balancing the emotional SNS and the intellectual SNS to achieve stability in a nontrivial autonomous environment with a Stability Algorithm for Neural Entities (SANE). Generating emotions from rules can include coding the rules into the rule-driven SNS in a self-consistent way. Training the emotional rule-driven SNS can occur during a training stage in parallel with training the choice-driven SNS. The training stage can include a self assessment loop which measures performance characteristics of the rule-driven SNS against core genetic code. The method uses a stability threshold to measure stability of the incorporated rule-driven SNS and choice-driven SNS using SANE.

Probing Carrier Transport and Structure-Property Relationship of Highly Ordered Organic Semiconductors at the Two-Dimensional Limit.

PubMed

Zhang, Yuhan; Qiao, Jingsi; Gao, Si; Hu, Fengrui; He, Daowei; Wu, Bing; Yang, Ziyi; Xu, Bingchen; Li, Yun; Shi, Yi; Ji, Wei; Wang, Peng; Wang, Xiaoyong; Xiao, Min; Xu, Hangxun; Xu, Jian-Bin; Wang, Xinran

2016-01-08

One of the basic assumptions in organic field-effect transistors, the most fundamental device unit in organic electronics, is that charge transport occurs two dimensionally in the first few molecular layers near the dielectric interface. Although the mobility of bulk organic semiconductors has increased dramatically, direct probing of intrinsic charge transport in the two-dimensional limit has not been possible due to excessive disorders and traps in ultrathin organic thin films. Here, highly ordered single-crystalline mono- to tetralayer pentacene crystals are realized by van der Waals (vdW) epitaxy on hexagonal BN. We find that the charge transport is dominated by hopping in the first conductive layer, but transforms to bandlike in subsequent layers. Such an abrupt phase transition is attributed to strong modulation of the molecular packing by interfacial vdW interactions, as corroborated by quantitative structural characterization and density functional theory calculations. The structural modulation becomes negligible beyond the second conductive layer, leading to a mobility saturation thickness of only ∼3  nm. Highly ordered organic ultrathin films provide a platform for new physics and device structures (such as heterostructures and quantum wells) that are not possible in conventional bulk crystals.

Probing Carrier Transport and Structure-Property Relationship of Highly Ordered Organic Semiconductors at the Two-Dimensional Limit

NASA Astrophysics Data System (ADS)

Zhang, Yuhan; Qiao, Jingsi; Gao, Si; Hu, Fengrui; He, Daowei; Wu, Bing; Yang, Ziyi; Xu, Bingchen; Li, Yun; Shi, Yi; Ji, Wei; Wang, Peng; Wang, Xiaoyong; Xiao, Min; Xu, Hangxun; Xu, Jian-Bin; Wang, Xinran

2016-01-01

One of the basic assumptions in organic field-effect transistors, the most fundamental device unit in organic electronics, is that charge transport occurs two dimensionally in the first few molecular layers near the dielectric interface. Although the mobility of bulk organic semiconductors has increased dramatically, direct probing of intrinsic charge transport in the two-dimensional limit has not been possible due to excessive disorders and traps in ultrathin organic thin films. Here, highly ordered single-crystalline mono- to tetralayer pentacene crystals are realized by van der Waals (vdW) epitaxy on hexagonal BN. We find that the charge transport is dominated by hopping in the first conductive layer, but transforms to bandlike in subsequent layers. Such an abrupt phase transition is attributed to strong modulation of the molecular packing by interfacial vdW interactions, as corroborated by quantitative structural characterization and density functional theory calculations. The structural modulation becomes negligible beyond the second conductive layer, leading to a mobility saturation thickness of only ˜3 nm . Highly ordered organic ultrathin films provide a platform for new physics and device structures (such as heterostructures and quantum wells) that are not possible in conventional bulk crystals.

Noncoplanar VMAT for nasopharyngeal tumors: Plan quality versus treatment time.

PubMed

Wild, Esther; Bangert, Mark; Nill, Simeon; Oelfke, Uwe

2015-05-01

The authors investigated the potential of optimized noncoplanar irradiation trajectories for volumetric modulated arc therapy (VMAT) treatments of nasopharyngeal patients and studied the trade-off between treatment plan quality and delivery time in radiation therapy. For three nasopharyngeal patients, the authors generated treatment plans for nine different delivery scenarios using dedicated optimization methods. They compared these scenarios according to dose characteristics, number of beam directions, and estimated delivery times. In particular, the authors generated the following treatment plans: (1) a 4π plan, which is a not sequenced, fluence optimized plan that uses beam directions from approximately 1400 noncoplanar directions and marks a theoretical upper limit of the treatment plan quality, (2) a coplanar 2π plan with 72 coplanar beam directions as pendant to the noncoplanar 4π plan, (3) a coplanar VMAT plan, (4) a coplanar step and shoot (SnS) plan, (5) a beam angle optimized (BAO) coplanar SnS IMRT plan, (6) a noncoplanar BAO SnS plan, (7) a VMAT plan with rotated treatment couch, (8) a noncoplanar VMAT plan with an optimized great circle around the patient, and (9) a noncoplanar BAO VMAT plan with an arbitrary trajectory around the patient. VMAT using optimized noncoplanar irradiation trajectories reduced the mean and maximum doses in organs at risk compared to coplanar VMAT plans by 19% on average while the target coverage remains constant. A coplanar BAO SnS plan was superior to coplanar SnS or VMAT; however, noncoplanar plans like a noncoplanar BAO SnS plan or noncoplanar VMAT yielded a better plan quality than the best coplanar 2π plan. The treatment plan quality of VMAT plans depended on the length of the trajectory. The delivery times of noncoplanar VMAT plans were estimated to be 6.5 min in average; 1.6 min longer than a coplanar plan but on average 2.8 min faster than a noncoplanar SnS plan with comparable treatment plan quality. The authors' study reconfirms the dosimetric benefits of noncoplanar irradiation of nasopharyngeal tumors. Both SnS using optimized noncoplanar beam ensembles and VMAT using an optimized, arbitrary, noncoplanar trajectory enabled dose reductions in organs at risk compared to coplanar SnS and VMAT. Using great circles or simple couch rotations to implement noncoplanar VMAT, however, was not sufficient to yield meaningful improvements in treatment plan quality. The authors estimate that noncoplanar VMAT using arbitrary optimized irradiation trajectories comes at an increased delivery time compared to coplanar VMAT yet at a decreased delivery time compared to noncoplanar SnS IMRT.

One-pot, facile fabrication of a Ag3PO4-based ternary Z-scheme photocatalyst with excellent visible-light photoactivity and anti-photocorrosion performance

NASA Astrophysics Data System (ADS)

Xie, Mingyuan; Zhang, Tailiang

2018-04-01

Ag3PO4 can-not be widely used as an efficient photocatalyst in practical applications because of its susceptibility to photocorrosion. In this study, a novel, ternary Z-scheme photocatalytic system containing graphene oxide (GO), Ag3PO4 and SnS2 was fabricated by a one-pot, mild, in-situ precipitation method successfully. Using Rhodamine B (RhB) as the target of elimination, GO/Ag3PO4/SnS2 exhibited outstanding photocatalytic and anti-photocorrosion properties compared with those of Ag3PO4, Ag3PO4/SnS2 and GO/Ag3PO4. RhB was thoroughly degraded over the optimized GO/Ag3PO4/SnS2 nanocomposite after only 15 min under visible-light irradiation; this result is approximately 2.14, 3.33 and 5.83 times faster than that of GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. After three reuses, the photocatalytic activity of the ternary composite slightly decreased but remained 2.36, 4.08 and 12.70 times higher than those of the reused GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. In this system, the efficient separation and migration of the photoinduced current carriers in Ag3PO4 was realized through a double Z-scheme electron-transfer mechanism in which the GO nanosheets acted as the photocatalyst and electron mediator, thereby enhancing the photoactivity and stability of Ag3PO4. The present study provides a new perspective for enhancing photocatalytic and anti-photocorrosion performances in perishable photocatalysts for organic sewage and other environmental contamination treatments.

Laparoscopic sentinel lymph node procedure using a combination of patent blue and radioisotope in women with cervical carcinoma.

PubMed

Barranger, Emmanuel; Grahek, Dany; Cortez, Annie; Talbot, Jean Noel; Uzan, Serge; Darai, Emile

2003-06-15

The authors evaluated the feasibility of a laparoscopic sentinel lymph node (SN) procedure with combined radioisotopic and patent blue labeling in patients with cervical carcinoma. Thirteen women (median age, 52.5 years) with cervical carcinoma (Stage Ia2 in 1 patient, Stage Ib1 in 10 patients, Stage Ib2 in 1 patient, and Stage IIa in 1 patient) underwent a laparoscopic SN procedure using an endoscopic gamma probe after both radioactive isotope and patent blue injections. After the procedure, all patients underwent complete laparoscopic pelvic lymphadenectomy and either laparoscopic radical hysterectomy (eight patients) or the Schauta-Amreich operation (five patients). SNs (mean, 1.7 SNs per patient; range, 1-3 SNs per patient) were identified in 12 of 13 patients. A median of 10.5 pelvic lymph nodes per patient (range, 4-17 pelvic lymph nodes per patient) were removed. No lymph node involvement was detected in SNs with hematoxylin and eosin staining. Immunohistochemical studies identified four metastatic SNs in two patients, with micrometastases in two SNs from the first patient and isolated tumor cells in two SNs from the second patient. No false-negative SN results were obtained. The results of this study suggest that SN detection with a combination of radiocolloid and patent blue is feasible in patients with cervical carcinoma. The combination of laparoscopy and the SN procedure permitted minimally invasive management of early-stage disease. Copyright 2003 American Cancer Society.

Compulsive use of social networking sites in Belgium: prevalence, profile, and the role of attitude toward work and school.

PubMed

De Cock, Rozane; Vangeel, Jolien; Klein, Annabelle; Minotte, Pascal; Rosas, Omar; Meerkerk, Gert-Jan

2014-03-01

A representative sample (n=1,000) of the Belgian population aged 18 years and older filled out an online questionnaire on their Internet use in general and their use of social networking sites (SNS) in particular. We measured total time spent on the Internet, time spent on SNS, number of SNS profiles, gender, age, schooling level, income, job occupation, and leisure activities, and we integrated several psychological scales such as the Quick Big Five and the Mastery Scale. Hierarchical multiple regression modeling shows that gender and age explain an important part of the compulsive SNS score (5%) as well as psychological scales (20%), but attitude toward school (additional 3%) and income (2.5%) also add to explained variance in predictive models of compulsive SNS use.

Sensing Properties of GO and Amine-Silica Nanoparticles Functionalized QCM Sensors for Detection of Formaldehyde

NASA Astrophysics Data System (ADS)

Wang, Zhenqiang; Yang, Mingqing; He, Junhui

2014-12-01

In the current work, graphene oxides (GO) and Amine-Functionalized Silica Nanoparticles (NH2-SNs) were used as sensing layer on quart crystal microbalance (QCM) for detection of HCHO gas. The GO and NH2-SNs functionalized QCM resonators all had a significant response to HCHO gas. The sensitivity of GO functionalized QCM resonator is 0.04 Hz/(μgṡppm), which is four times as high as that of NH2-SNs functionalized QCM resonator (0.01 Hz/(μgṡppm)). The GO functionalized QCM resonators would be of benefit in area of environmental applications.

van der Waals epitaxy of SnS film on single crystal graphene buffer layer on amorphous SiO2/Si

NASA Astrophysics Data System (ADS)

Xiang, Yu; Yang, Yunbo; Guo, Fawen; Sun, Xin; Lu, Zonghuan; Mohanty, Dibyajyoti; Bhat, Ishwara; Washington, Morris; Lu, Toh-Ming; Wang, Gwo-Ching

2018-03-01

Conventional hetero-epitaxial films are typically grown on lattice and symmetry matched single crystal substrates. We demonstrated the epitaxial growth of orthorhombic SnS film (∼500 nm thick) on single crystal, monolayer graphene that was transferred on the amorphous SiO2/Si substrate. Using X-ray pole figure analysis we examined the structure, quality and epitaxy relationship of the SnS film grown on the single crystal graphene and compared it with the SnS film grown on commercial polycrystalline graphene. We showed that the SnS films grown on both single crystal and polycrystalline graphene have two sets of orientation domains. However, the crystallinity and grain size of the SnS film improve when grown on the single crystal graphene. Reflection high-energy electron diffraction measurements show that the near surface texture has more phases as compared with that of the entire film. The surface texture of a film will influence the growth and quality of film grown on top of it as well as the interface formed. Our result offers an alternative approach to grow a hetero-epitaxial film on an amorphous substrate through a single crystal graphene buffer layer. This strategy of growing high quality epitaxial thin film has potential applications in optoelectronics.

Positively-charged reduced graphene oxide as an adhesion promoter for preparing a highly-stable silver nanowire film

NASA Astrophysics Data System (ADS)

Sun, Qijun; Lee, Seong Jun; Kang, Hyungseok; Gim, Yuseong; Park, Ho Seok; Cho, Jeong Ho

2015-04-01

An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3+) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3+, spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3+ ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion promoter are extremely stable under harsh conditions, including ultrasonication in a variety of solvents, 3M Scotch tape detachment test, mechanical bending up to 0.3% strain, or fatigue over 1000 cycles. The greatly enhanced adhesion force is attributed to the ionic interactions between the positively charged protonated amine groups in rGO-NH3+ and the negatively charged hydroxo- and oxo-groups on the AgNWs. The positively charged GO-NH3+ and commercial polycationic polymer (poly allylamine hydrochloride) are also prepared as adhesion promoters for comparison with rGO-NH3+. Notably, the closely packed hexagonal atomic structure of rGO offers better barrier properties to water permeation and demonstrates promising utility in durable waterproof electronics. This work offers a simple method to prepare high-quality TCEs and is believed to have great potential application in flexible waterproof electronics.An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3+) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3+, spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3+ ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion promoter are extremely stable under harsh conditions, including ultrasonication in a variety of solvents, 3M Scotch tape detachment test, mechanical bending up to 0.3% strain, or fatigue over 1000 cycles. The greatly enhanced adhesion force is attributed to the ionic interactions between the positively charged protonated amine groups in rGO-NH3+ and the negatively charged hydroxo- and oxo-groups on the AgNWs. The positively charged GO-NH3+ and commercial polycationic polymer (poly allylamine hydrochloride) are also prepared as adhesion promoters for comparison with rGO-NH3+. Notably, the closely packed hexagonal atomic structure of rGO offers better barrier properties to water permeation and demonstrates promising utility in durable waterproof electronics. This work offers a simple method to prepare high-quality TCEs and is believed to have great potential application in flexible waterproof electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00777a

Manganese-impregnated mesoporous silica nanoparticles for signal enhancement in MRI cell labelling studies

NASA Astrophysics Data System (ADS)

Guillet-Nicolas, Rémy; Laprise-Pelletier, Myriam; Nair, Mahesh M.; Chevallier, Pascale; Lagueux, Jean; Gossuin, Yves; Laurent, Sophie; Kleitz, Freddy; Fortin, Marc-André

2013-11-01

Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn2+ is already implemented as a ``positive'' cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(ii) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn2+ leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM-1 s-1 were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness, while maintaining an open porosity and relatively high pore volume. Because these Mn-labelled M48SNs express strong ``positive'' contrast media properties at low concentrations, they are potentially applicable for cell tracking and drug delivery methodologies.Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn2+ is already implemented as a ``positive'' cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(ii) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn2+ leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM-1 s-1 were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness, while maintaining an open porosity and relatively high pore volume. Because these Mn-labelled M48SNs express strong ``positive'' contrast media properties at low concentrations, they are potentially applicable for cell tracking and drug delivery methodologies. Electronic supplementary information (ESI) available: TEM images, particle size distributions, XRD, TPR, magnetometric profiles, T1 and T2 measurements at 60 MHz over time, NMRD profiles of materials, P388 cell proliferation assay after 4 h and T1-w. MR images of P388 cells incubated with a solution of M48SNs. See DOI: 10.1039/c3nr02969g

The Mediating Roles of Upward Social Comparison and Self-esteem and the Moderating Role of Social Comparison Orientation in the Association between Social Networking Site Usage and Subjective Well-Being.

PubMed

Wang, Jin-Liang; Wang, Hai-Zhen; Gaskin, James; Hawk, Skyler

2017-01-01

The increased pervasiveness of social media use has raised questions about potential effects on users' subjective well-being, with studies reaching contrasting conclusions. To reconcile these discrepancies and shed new light on this phenomenon, the current study examined: (1) whether upward social comparison and self-esteem mediate the association between social networking site (SNS) usage and users' subjective well-being, and (2) whether the association between SNS usage and upward social comparison is moderated by users' social comparison orientation. Data from 696 participants were collected. Structural equation modeling revealed that upward social comparison and self-esteem mediated the relationship between SNS usage and users' subjective well-being. We found that social comparison orientation moderated the association between passive SNS usage and users' upward social comparison. Specifically, social comparison orientation strengthened the association between passive SNS usage and upward social comparison. The results might suggest a process through which passive SNS usage is related to subjective well-being, and identify a context under which these associations may differ.

The Mediating Roles of Upward Social Comparison and Self-esteem and the Moderating Role of Social Comparison Orientation in the Association between Social Networking Site Usage and Subjective Well-Being

PubMed Central

Wang, Jin-Liang; Wang, Hai-Zhen; Gaskin, James; Hawk, Skyler

2017-01-01

The increased pervasiveness of social media use has raised questions about potential effects on users’ subjective well-being, with studies reaching contrasting conclusions. To reconcile these discrepancies and shed new light on this phenomenon, the current study examined: (1) whether upward social comparison and self-esteem mediate the association between social networking site (SNS) usage and users’ subjective well-being, and (2) whether the association between SNS usage and upward social comparison is moderated by users’ social comparison orientation. Data from 696 participants were collected. Structural equation modeling revealed that upward social comparison and self-esteem mediated the relationship between SNS usage and users’ subjective well-being. We found that social comparison orientation moderated the association between passive SNS usage and users’ upward social comparison. Specifically, social comparison orientation strengthened the association between passive SNS usage and upward social comparison. The results might suggest a process through which passive SNS usage is related to subjective well-being, and identify a context under which these associations may differ. PMID:28553256

Microwave assisted synthesis of porous ZnO/SnS heterojunction and its application in visible light degradation of ciprofloxacin

NASA Astrophysics Data System (ADS)

Makama, A. B.; Salmiaton, A.; Saion, E. B.; Choong, T. S. Y.; Abdullah, N.

2016-07-01

Porous ZnO/SnS heterojunctions were successfully synthesized via microwave-assisted heating of aqueous solutions containing different amounts of SnS precursors (SnCl2 and Na2S) in the presence of fixed amount of ZnCO3 nanoparticles. The experimental results revealed that the heterojunctions exhibited much higher visible light-driven photocatalytic activity for the degradation of the ciprofloxacin than pure SnS nanocrystals. The photocatalytic degradation efficiency (1-Ct/C0) of the pollutant for the most active heterogeneous nanostructure is about four times more efficient than pure SnS. The enhanced photocatalytic efficiency is ascribed to the synergic effect of high photon absorption and reduction in the recombination of electrons and holes because of efficient separation and electron transfer from the SnS to ZnO nanoparticles.

Synthesis of SnS2/SnS fullerene-like nanoparticles: a superlattice with polyhedral shape.

PubMed

Hong, Sung You; Popovitz-Biro, Ronit; Prior, Yehiam; Tenne, Reshef

2003-08-27

Tin disulfide pellets were laser ablated in an inert gas atmosphere, and closed cage fullerene-like (IF) nanoparticles were produced. The nanoparticles had various polyhedra and short tubular structures. Some of these forms contained a periodic pattern of fringes resulting in a superstructure. These patterns could be assigned to a superlattice created by periodic stacking of layered SnS(2) and SnS. Such superlattices are reminiscent of misfit layer compounds, which are known to form tubular morphologies. This mechanism adds up to the established mechanism for IF formation, namely, the annihilation of reactive dangling bonds at the periphery of the nanoparticles. Additionally, it suggests that one of the driving forces to form tubules in misfit compounds is the annihilation of dangling bonds at the rim of the layered structure.

Thermoelectric materials by using two-dimensional materials with negative correlation between electrical and thermal conductivity

PubMed Central

Lee, Myoung-Jae; Ahn, Ji-Hoon; Sung, Ji Ho; Heo, Hoseok; Jeon, Seong Gi; Lee, Woo; Song, Jae Yong; Hong, Ki-Ha; Choi, Byeongdae; Lee, Sung-Hoon; Jo, Moon-Ho

2016-01-01

In general, in thermoelectric materials the electrical conductivity σ and thermal conductivity κ are related and thus cannot be controlled independently. Previously, to maximize the thermoelectric figure of merit in state-of-the-art materials, differences in relative scaling between σ and κ as dimensions are reduced to approach the nanoscale were utilized. Here we present an approach to thermoelectric materials using tin disulfide, SnS2, nanosheets that demonstrated a negative correlation between σ and κ. In other words, as the thickness of SnS2 decreased, σ increased whereas κ decreased. This approach leads to a thermoelectric figure of merit increase to 0.13 at 300 K, a factor ∼1,000 times greater than previously reported bulk single-crystal SnS2. The Seebeck coefficient obtained for our two-dimensional SnS2 nanosheets was 34.7 mV K−1 for 16-nm-thick samples at 300 K. PMID:27323662

Perceptions of Pediatric Residents Regarding Counseling About Use of Social Networking Sites.

PubMed

Banker, Sumeet L; Fenick, Ada M; Qin, Li; Talwalkar, Jaideep S

2018-04-01

Increasing use of social networking sites (SNS) among youth prompted professional organizations to urge pediatricians to promote healthy media use. Electronic questionnaires were distributed to 76 pediatric residents at one academic center measuring attitudes, practices, and familiarity with SNS. Of 43 respondents (response rate = 57%), most reported personal SNS use (98%) and familiarity with SNS used by youth (72%), and 88% agreed that pediatricians should provide counseling on SNS use. Only 5% felt they had adequate training on SNS use in children, and just 26% felt comfortable advising families. Residents were less likely to discuss SNS use than general media use (19% vs 56%, P = .007). Media counseling was correlated with SNS counseling ( r = .38, P = .01). Pediatric residents recognize the importance of guiding families on SNS use, yet do not routinely provide counseling despite high levels of personal SNS use and familiarity. Focused training is necessary for pediatricians to prioritize practical guidance.

Characterization and manipulation of individual defects in insulating hexagonal boron nitride using scanning tunnelling microscopy.

PubMed

Wong, Dillon; Velasco, Jairo; Ju, Long; Lee, Juwon; Kahn, Salman; Tsai, Hsin-Zon; Germany, Chad; Taniguchi, Takashi; Watanabe, Kenji; Zettl, Alex; Wang, Feng; Crommie, Michael F

2015-11-01

Defects play a key role in determining the properties and technological applications of nanoscale materials and, because they tend to be highly localized, characterizing them at the single-defect level is of particular importance. Scanning tunnelling microscopy has long been used to image the electronic structure of individual point defects in conductors, semiconductors and ultrathin films, but such single-defect electronic characterization remains an elusive goal for intrinsic bulk insulators. Here, we show that individual native defects in an intrinsic bulk hexagonal boron nitride insulator can be characterized and manipulated using a scanning tunnelling microscope. This would typically be impossible due to the lack of a conducting drain path for electrical current. We overcome this problem by using a graphene/boron nitride heterostructure, which exploits the atomically thin nature of graphene to allow the visualization of defect phenomena in the underlying bulk boron nitride. We observe three different defect structures that we attribute to defects within the bulk insulating boron nitride. Using scanning tunnelling spectroscopy we obtain charge and energy-level information for these boron nitride defect structures. We also show that it is possible to manipulate the defects through voltage pulses applied to the scanning tunnelling microscope tip.

ABCB1 as predominant resistance mechanism in cells with acquired SNS-032 resistance

PubMed Central

Rothweiler, Florian; Voges, Yvonne; Balónová, Barbora; Blight, Barry A.; Cinatl, Jindrich

2016-01-01

The CDK inhibitor SNS-032 had previously exerted promising anti-neuroblastoma activity via CDK7 and 9 inhibition. ABCB1 expression was identified as major determinant of SNS-032 resistance. Here, we investigated the role of ABCB1 in acquired SNS-032 resistance. In contrast to ABCB1-expressing UKF-NB-3 sub-lines resistant to other ABCB1 substrates, SNS-032-adapted UKF-NB-3 (UKF-NB-3rSNS- 032300nM) cells remained sensitive to the non-ABCB1 substrate cisplatin and were completely re-sensitized to cytotoxic ABCB1 substrates by ABCB1 inhibition. Moreover, UKF-NB-3rSNS-032300nM cells remained similarly sensitive to CDK7 and 9 inhibition as UKF-NB-3 cells. In contrast, SHEPrSNS-0322000nM, the SNS-032-resistant sub-line of the neuroblastoma cell line SHEP, displayed low level SNS-032 resistance also when ABCB1 was inhibited. This discrepancy may be explained by the higher SNS-032 concentrations that were used to establish SHEPrSNS-0322000nM cells, since SHEP cells intrinsically express ABCB1 and are less sensitive to SNS-032 (IC50 912 nM) than UKF-NB-3 cells (IC50 153 nM). In conclusion, we show that ABCB1 expression represents the primary (sometimes exclusive) resistance mechanism in neuroblastoma cells with acquired resistance to SNS-032. Thus, ABCB1 inhibitors may increase the SNS-032 efficacy in ABCB1-expressing cells and prolong or avoid resistance formation. PMID:27517323

Three-year cost-effectiveness model for non-animal stabilized hyaluronic acid and dextranomer copolymer compared with sacral nerve stimulation after conservative therapy for the management of fecal incontinence.

PubMed

Bernstein, Mitchell A; Purdy, Christopher H; Becker, Alison; Magar, Raf

2014-06-01

Two new therapies for fecal incontinence (FI) are now available: non-animal stabilized hyaluronic acid and dextranomer copolymer (NASHA/Dx) and sacral nerve stimulation (SNS). This study aimed to determine the cost-effectiveness of NASHA/Dx compared with SNS and conservative therapy (CT) for the treatment of FI after CT failure. Decision tree models with Markov subbranches were developed to compare all direct costs and outcomes during a 3-year period from the viewpoint of the US third-party payer. Costs (in 2013 US dollars) of devices, medical and surgical care, and hospitalization were included. Outcomes included quality-adjusted life-years (QALYs) and incontinence-free days (IFDs). Both costs and outcomes were discounted at an annual rate of 3%. The incremental cost-effectiveness ratio was calculated for each outcome. One-way and probabilistic sensitivity analyses were performed to examine robustness of results and model stability. A budget impact analysis was also undertaken to estimate the potential cost and savings of NASHA/Dx for a payer with 1,000,000 covered lives. For the 3-year cost-effectiveness models, the expected cost was $9053 for CT, $14,962 for NASHA/Dx, and $33,201 for SNS. The numbers of QALYs were 1.769, 1.929, and 2.004, respectively. The numbers of IFDs were 128.8, 267.6, and 514.8, respectively. The incremental cost-effectiveness ratios per additional IFD gained were $42.60 for NASHA/Dx vs CT, $73.76 for SNS vs NASHA/Dx, and $62.55 for SNS vs CT. The incremental costs per QALY gained were $37,036 for NASHA/Dx vs CT, $244,509 for SNS vs NASHA/Dx, and $103,066 for SNS vs CT. The budget impact analysis evaluated the financial effect on the health care system of the use of NASHA/Dx and SNS. For the scenarios evaluated, when all of the patients receive NASHA/Dx, the net annual effect to the health care payer budget ranged from $571,455 to $2,857,275. When all of the patients receive SNS, the net annual effect to the health care payer budget ranged from $1,959,323 to $9,796,613. Both NASHA/Dx and SNS have produced significant improvements in FI symptoms for affected patients. NASHA/Dx is a cost-effective and more efficient use of resources for the treatment of FI when compared with SNS. The budget impact analysis suggests that although reimbursement for NASHA/Dx treatment initially adds costs to the health care system, it is significantly less expensive than SNS for patients who are candidates for either treatment. Copyright © 2014 The Authors. Published by EM Inc USA.. All rights reserved.

Subsequent neoplasms in survivors of childhood central nervous system tumors: risk after modern multimodal therapy.

PubMed

Tsui, Karen; Gajjar, Amar; Li, Chenghong; Srivastava, Deokumar; Broniscer, Alberto; Wetmore, Cynthia; Kun, Larry E; Merchant, Thomas E; Ellison, David W; Orr, Brent A; Boop, Frederick A; Klimo, Paul; Ross, Jordan; Robison, Leslie L; Armstrong, Gregory T

2015-03-01

Multimodal therapy has improved survival for some childhood CNS tumors. However, whether risk for subsequent neoplasms (SNs) also increases is unknown. We report the cumulative incidence of, and risk factors for, SNs after a childhood primary CNS tumor and determine whether treatment that combines radiation therapy (RT) with chemotherapy increases risk for SNs. Analyses included 2779 patients with a primary CNS tumor treated at St Jude Children's Research Hospital between 1985 and 2012. Cumulative incidence and standardized incidence ratios (SIRs) were estimated for SNs confirmed by pathology report. Cumulative incidence among the 237 five-year medulloblastoma survivors treated with multimodal therapy (RT + chemotherapy) was compared with a historical cohort of 139 five-year survivors treated with RT but no chemotherapy in the Childhood Cancer Survivor Study. Eighty-one survivors had 97 SNs. The cumulative incidence of first SN was 3.0% (95% CI: 2.3%-3.9%) at 10 years, and 6.0% (95% CI: 4.6%-7.7%) at 20 years from diagnosis. Risks were highest for subsequent glioma, all grades (SIR = 57.2; 95% CI: 36.2-85.8) and acute myeloid leukemia (SIR = 31.8; 95% CI: 10.2-74.1). Compared with RT alone, RT + chemotherapy did not increase risk for SNs (hazard ratio: 0.64; 95% CI: 0.38-1.06). Among five-year survivors of medulloblastoma treated with multimodal therapy, cumulative incidence of SN was 12.0% (95% CI: 6.4%-19.5%) at 20 years, no different than survivors treated with RT alone (11.3%, P = .44). The cumulative incidence of SNs continues to increase with time from treatment with no obvious plateau, but the risk does not appear to be higher after exposure to multimodal therapy compared with RT alone. Continued follow-up of survivors as they age is essential. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Noncoplanar VMAT for nasopharyngeal tumors: Plan quality versus treatment time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wild, Esther, E-mail: e.wild@dkfz.de; Bangert, Mark; Nill, Simeon

Purpose: The authors investigated the potential of optimized noncoplanar irradiation trajectories for volumetric modulated arc therapy (VMAT) treatments of nasopharyngeal patients and studied the trade-off between treatment plan quality and delivery time in radiation therapy. Methods: For three nasopharyngeal patients, the authors generated treatment plans for nine different delivery scenarios using dedicated optimization methods. They compared these scenarios according to dose characteristics, number of beam directions, and estimated delivery times. In particular, the authors generated the following treatment plans: (1) a 4π plan, which is a not sequenced, fluence optimized plan that uses beam directions from approximately 1400 noncoplanar directionsmore » and marks a theoretical upper limit of the treatment plan quality, (2) a coplanar 2π plan with 72 coplanar beam directions as pendant to the noncoplanar 4π plan, (3) a coplanar VMAT plan, (4) a coplanar step and shoot (SnS) plan, (5) a beam angle optimized (BAO) coplanar SnS IMRT plan, (6) a noncoplanar BAO SnS plan, (7) a VMAT plan with rotated treatment couch, (8) a noncoplanar VMAT plan with an optimized great circle around the patient, and (9) a noncoplanar BAO VMAT plan with an arbitrary trajectory around the patient. Results: VMAT using optimized noncoplanar irradiation trajectories reduced the mean and maximum doses in organs at risk compared to coplanar VMAT plans by 19% on average while the target coverage remains constant. A coplanar BAO SnS plan was superior to coplanar SnS or VMAT; however, noncoplanar plans like a noncoplanar BAO SnS plan or noncoplanar VMAT yielded a better plan quality than the best coplanar 2π plan. The treatment plan quality of VMAT plans depended on the length of the trajectory. The delivery times of noncoplanar VMAT plans were estimated to be 6.5 min in average; 1.6 min longer than a coplanar plan but on average 2.8 min faster than a noncoplanar SnS plan with comparable treatment plan quality. Conclusions: The authors’ study reconfirms the dosimetric benefits of noncoplanar irradiation of nasopharyngeal tumors. Both SnS using optimized noncoplanar beam ensembles and VMAT using an optimized, arbitrary, noncoplanar trajectory enabled dose reductions in organs at risk compared to coplanar SnS and VMAT. Using great circles or simple couch rotations to implement noncoplanar VMAT, however, was not sufficient to yield meaningful improvements in treatment plan quality. The authors estimate that noncoplanar VMAT using arbitrary optimized irradiation trajectories comes at an increased delivery time compared to coplanar VMAT yet at a decreased delivery time compared to noncoplanar SnS IMRT.« less

Damping the e-p instability in the SNS accumulator ring

NASA Astrophysics Data System (ADS)

Evans, N. J.; Deibele, C.; Aleksandrov, A.; Xie, Z.

2018-03-01

A broadband, digital damper system for both transverse planes developed for the SNS accumulator ring has recently damped the first indications of the broadband 50-150 MHz e-p instability in a 1.2 MW neutron production beam. This paper presents details of the design and operation of the SNS damper system as well as results of active damping of the e-p instability in the SNS ring showing a reduction in power of betatron oscillation over the 10-300 MHz band of up to 70%. The spectral content of the beam during operation, with and without the damper system is presented and performance of the damper system is evaluated.

Mechanism of Antiwear Property Under High Pressure of Synthetic Oil-Soluble Ultrathin MoS2 Sheets as Lubricant Additives.

PubMed

Chen, Zhe; Liu, Yuhong; Gunsel, Selda; Luo, Jianbin

2018-01-30

Wear occurs between two rubbing surfaces. Severe wear due to seizure under high pressure leads to catastrophic failures of mechanical systems and raises wide concerns. In this paper, a kind of synthetic oil-soluble ultrathin MoS 2 sheets is synthesized and investigated as lubricant additives between steel surfaces. It is found that, with the ultrathin MoS 2 sheets, the wear can be controlled under the nominal pressure of about 1 GPa, whereas the bearable nominal pressure for traditional lubricants is only a few hundred megapascals. It is found that when wear is under control, the real pressure between the asperities agrees with the breaking strength of ultrathin MoS 2 . Therefore, it is believed that, because of the good oil solubility and ultrasmall thickness, the ultrathin MoS 2 sheets can easily enter the contact area between the contacting asperities. Then, the localized seizure and further wear are prevented because there will be no metal-to-metal contact as long as the real pressure between the asperities is below the breaking strength of ultrathin MoS 2 . In this way, the upper limit pressure the lubricant can work is dependent on the mechanical properties of the containing ultrathin two-dimensional (2D) sheets. Additionally, ultrathin MoS 2 sheets with various lateral sizes are compared, and it is found that sheets with a larger size show better lubrication performance. This work discovers the lubrication mechanism of ultrathin MoS 2 sheets as lubricant additives and provides an inspiration to develop a novel generation of lubricant additives with high-strength ultrathin 2D materials.

Electrical Stressing Induced Monolayer Vacancy Island Growth on TiSe2

NASA Astrophysics Data System (ADS)

Zheng, Husong; Valtierra, Salvador; Ofori-Opoku, Nana; Chen, Chuanhui; Sun, Lifei; Yuan, Shuaishuai; Jiao, Liying; Bevan, Kirk H.; Tao, Chenggang

2018-03-01

To ensure the practical application of atomically thin transition metal dichalcogenides, it is essential to characterize their structural stability under external stimuli such as electric fields and currents. Using vacancy monolayer islands on TiSe2 surfaces as a model system, for the first time we have observed a shape evolution and growth from triangular to hexagonal driven by scanning tunneling microscopy (STM) electrical stressing. The size of islands shows linear growth with a rate of (3.00 +- 0.05) x 10-3 nm/s, when the STM scanning parameters are held fixed at Vs = 1.0 V and I = 1.8 nA. We further quantified how the growth rate is related to the tunneling current magnitude. Our simulations of monolayer island evolution using phase-field modeling are in good agreement with our experimental observations, and point towards preferential edge atom dissociation under STM scanning driving the observed growth. The results could be potentially important for device applications of ultrathin transition metal dichalcogenides and related 2D materials subject to electrical stressing under device operating conditions.

Ultrathin 2D Photocatalysts: Electronic-Structure Tailoring, Hybridization, and Applications.

PubMed

Di, Jun; Xiong, Jun; Li, Huaming; Liu, Zheng

2018-01-01

As a sustainable technology, semiconductor photocatalysis has attracted considerable interest in the past several decades owing to the potential to relieve or resolve energy and environmental-pollution issues. By virtue of their unique structural and electronic properties, emerging ultrathin 2D materials with appropriate band structure show enormous potential to achieve efficient photocatalytic performance. Here, the state-of-the-art progress on ultrathin 2D photocatalysts is reviewed and a critical appraisal of the classification, controllable synthesis, and formation mechanism of ultrathin 2D photocatalysts is presented. Then, different strategies to tailor the electronic structure of ultrathin 2D photocatalysts are summarized, including component tuning, thickness tuning, doping, and defect engineering. Hybridization with the introduction of a foreign component and maintaining the ultrathin 2D structure is presented to further boost the photocatalytic performance, such as quantum dots/2D materials, single atoms/2D materials, molecular/2D materials, and 2D-2D stacking materials. More importantly, the advancement of versatile photocatalytic applications of ultrathin 2D photocatalysts in the fields of water oxidation, hydrogen evolution, CO 2 reduction, nitrogen fixation, organic syntheses, and removal pollutants is discussed. Finally, the future opportunities and challenges regarding ultrathin 2D photocatalysts to bring about new opportunities for future research in the field of photocatalysis are also presented. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Social Network Sites as a Mode to Collect Health Data: A Systematic Review

PubMed Central

Ramzan, Farzan; Rawaf, Salman; Majeed, Azeem

2014-01-01

Background To date, health research literature has focused on social network sites (SNS) either as tools to deliver health care, to study the effect of these networks on behavior, or to analyze Web health content. Less is known about the effectiveness of these sites as a method for collecting data for health research and the means to use such powerful tools in health research. Objective The objective of this study was to systematically review the available literature and explore the use of SNS as a mode of collecting data for health research. The review aims to answer four questions: Does health research employ SNS as method for collecting data? Is data quality affected by the mode of data collection? What types of participants were reached by SNS? What are the strengths and limitations of SNS? Methods The literature was reviewed systematically in March 2013 by searching the databases MEDLINE, Embase, and PsycINFO, using the Ovid and PubMed interface from 1996 to the third week of March 2013. The search results were examined by 2 reviewers, and exclusion, inclusion, and quality assessment were carried out based on a pre-set protocol. Results The inclusion criteria were met by 10 studies and results were analyzed descriptively to answer the review questions. There were four main results. (1) SNS have been used as a data collection tool by health researchers; all but 1 of the included studies were cross-sectional and quantitative. (2) Data quality indicators that were reported include response rate, cost, timeliness, missing data/completion rate, and validity. However, comparison was carried out only for response rate and cost as it was unclear how other reported indicators were measured. (3) The most targeted population were females and younger people. (4) All studies stated that SNS is an effective recruitment method but that it may introduce a sampling bias. Conclusions SNS has a role in health research, but we need to ascertain how to use it effectively without affecting the quality of research. The field of SNS is growing rapidly, and it is necessary to take advantage of the strengths of this tool and to avoid its limitations by effective research design. This review provides an important insight for scholars who plan to conduct research using SNS. PMID:25048247

Sacral Nerve Stimulation For Urinary Urge Incontinence, Urgency-Frequency, Urinary Retention, and Fecal Incontinence

PubMed Central

2005-01-01

Executive Summary Objective The aim of this review was to assess the effectiveness, safety, and cost of sacral nerve stimulation (SNS) to treat urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. Background: Condition and Target Population Urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence are prevalent, yet rarely discussed, conditions. They are rarely discussed because patients may be uncomfortable disclosing their symptoms to a health professional or may be unaware that there are treatment options for these conditions. Briefly, urge incontinence is an involuntary loss of urine upon a sudden urge. Urgency-frequency is an uncontrollable urge to void, which results in frequent, small-volume voids. People with urgency-frequency may or may not also experience chronic pelvic pain. Urinary retention refers to the inability to void despite having the urge to void. It can be caused by a hypocontractile detrusor (weak or no bladder muscle contraction) or obstruction due to urethral overactivity. Fecal incontinence is a loss of voluntary bowel control. The prevalence of urge incontinence, urgency-frequency, and urinary retention in the general population is 3.3% to 8.2%, and the prevalence of fecal incontinence is 1.4% to 1.9%. About three-quarters of these people will be successfully treated by behaviour and/or drug therapy. For those who do not respond to these therapies, the options for treatment are management with diapers or pads, or surgery. The surgical procedures are generally quite invasive, permanent, and are associated with complications. Pads and/or diapers are used throughout the course of treatment as different therapies are tried. Patients who respond successfully to treatment may still require pads or diapers, but to a lesser extent. The Technology Being Reviewed: Sacral Nerve Stimulation Sacral nerve stimulation is a procedure where a small device attached to an electrode is implanted in the abdomen or buttock to stimulate the sacral nerves in an attempt to manage urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. The device was originally developed to manage urinary urge incontinence; however, it has also been used in patients with urgency-frequency, urinary retention, and fecal incontinence. SNS is intended for patients who are refractory to behaviour, drug, and/or interventional therapy. There are 2 phases in the SNS process: first, patients must undergo a test stimulation phase to determine if they respond to sacral nerve stimulation. If there is a 50% or greater improvement in voiding function, then the patient is considered a candidate for the next phase, implantation. Review Strategy The standard Medical Advisory Secretariat search strategy was used to locate international health technology assessments and English-language journal articles published from 2000 to November 2004. The Medical Advisory Secretariat also conducted Internet searches of Medscape (1) and the manufacturer’s website (2) to identify product information and recent reports on trials that were unpublished but that were presented at international conferences. In addition, the Web site Current Controlled Trials (3) was searched for ongoing randomized controlled trials (RCTs) investigating the role of sacral nerve stimulation in the management of voiding conditions. Summary of Findings Four health technology assessments were found that reviewed SNS in patients with urge incontinence, urgency-frequency, and/or urinary retention. One assessment was found that reviewed SNS in patients with fecal incontinence. The assessments consistently reported that SNS was an effective technology in managing these voiding conditions in patients who did not respond to drug or behaviour therapy. They also reported that there was a substantial complication profile associated with SNS. Complication rates ranged from 33% to 50%. However, none of the assessments reported that they found any incidences of permanent injury or death associated with the device. The health technology assessments for urge incontinence, urgency-frequency, and urinary retention included (RCTs (level 2) as their primary source of evidence for their conclusions. The assessment of fecal incontinence based its conclusions on evidence from case series (level 4). Because there was level 2 data available for the use of SNS in patients with urinary conditions, the Medical Advisory Secretariat chose to review thoroughly the RCTs included in the assessments and search for publications since the assessments were released. However, for the health technology assessment for fecal incontinence, which contained only level 4 evidence, the Medical Advisory Secretariat searched for studies on SNS and fecal incontinence that were published since that assessment was released. Urge Incontinence Two RCTs were identified that compared SNS to no treatment in patients with refractory urge incontinence. Both RCTs reported significant improvements (> 50% improvement in voiding function) in the SNS group for number of incontinence episodes per day, number of pads used per day, and severity of incontinence episodes. Urgency-Frequency (With or Without Chronic Pelvic Pain) One RCT was identified that compared SNS to no treatment in patients with refractory urgency-frequency. The RCT reported significant improvements in urgency-frequency symptoms in the SNS group (average volume per void, detrusor pressure). In addition to the RCT, 1 retrospective review and 2 prospective case series were identified that measured pelvic pain associated with urgency-frequency in patients who underwent SNS. All 3 studies reported a significant decrease in pain at median follow-up. Urinary Retention One RCT was identified that compared SNS to no treatment in patients with refractory urinary retention. The RCT reported significant improvements in urinary retention in the SNS group compared to the control group for number of catheterizations required and number of voids per day. In addition to this RCT, 1 case series was also identified investigating SNS in women with urinary retention. This study also found that there were significant improvements in urinary retention after the women had received the SNS implants. Fecal Incontinence Three case series were identified that investigated the role of SNS in patients with fecal incontinence. All 3 reported significant improvements in fecal incontinence symptoms (number of incontinent episodes per week) after the patients received the SNS implants. Long-Term Follow-up None of the studies identified followed patients until the point of battery failure. Of the 6 studies identified describing the long-term follow-up of patients with SNS, follow-up periods ranged from 1.5 years to over 5 years. None of the long-term follow-up studies included patients with fecal incontinence. All of the studies reported that most of the patients who had SNS had at least a 50% improvement in voiding function (range 58%–77%). These studies also reported the number of patients who had their device explanted in the follow-up period. The rates of explantation ranged from 12% to 21%. Safety, Complications, and Quality of Life A 33% surgical revision rate was reported in an analysis of the safety of 3 RCTs comparing SNS to no treatment in patients with urge incontinence, urgency-frequency, or urinary retention. The most commonly reported adverse effects were pain at the implant site and lead migration. Despite the high rate of surgical revision, there were no reports of permanent injury or death in any of the studies or health technology assessments identified. Additionally, patients consistently said that they would recommend the procedure to a friend or family member. Economic Analysis One health technology assessment and 1 abstract were found that investigated the costing factors pertinent to SNS. The authors of this assessment did their own “indicative analysis” and found that SNS was not more cost-effective than using incontinence supplies. However, the assessment did not account for quality of life. Conversely, the authors of the abstract found that SNS was more cost-effective than incontinence supplies alone; however, they noted that in the first year after SNS, it is much more expensive than only incontinence supplies. This is owing to the cost of the procedure, and the adjustments required to make the device most effective. They also noted the positive effects that SNS had on quality of life. Conclusions and Implications In summary, there is level 2 evidence to support the effectiveness of SNS to treat people with urge incontinence, urgency-frequency, or urinary retention. There is level 4 evidence to support the effectiveness of SNS to treat people with fecal incontinence. To qualify for SNS, people must meet the following criteria: Be refractory to behaviour and/or drug therapy Have had a successful test stimulation before implantation; successful test stimulation is defined by a 50% or greater improvement in voiding function based on the results of a voiding diary. Test stimulation periods range from 3 to 7 days for patients with urinary dysfunctions, and from 2 to 3 weeks for patients with fecal incontinence. Be able to record voiding diary data, so that clinical results of the implantation can be evaluated. Patients with stress incontinence, urinary retention due to obstruction and neurogenic conditions (such as diabetes with peripheral nerve involvement) are ineligible for sacral nerve stimulation. Physicians will need to learn how to use the InterStim System for Urinary Control. Requirements for training include these: Physicians must be experienced in the diagnosis and treatment of lower urinary tract disorders and should be trained in the implantation and use of the InterStim System for Urinary Control. Training should include the following: Participation in a seminar or workshop that includes instructional and laboratory training on SNS. This seminar should include a review of the evidence on SNS with emphasis on techniques to prevent adverse events. Completion of proctoring by a physician experienced in SNS for the first 2 test stimulations and the first 2 implants PMID:23074472

Discovery of New Mineral Butianite, Ni6SnS2, an Alteration Phase from Allende

NASA Astrophysics Data System (ADS)

Ma, C.

2017-07-01

Butianite (Ni6SnS2) is a new chalcogenide mineral from an Allende CAI, along with nuwaite (Ni6GeS2), formed from a late-stage sulfidation process, where Ni-Fe metals reacted with a low-temperature fluid enriched in S, Ge, Sn and Te.

Improving cycle stability of SnS anode for sodium-ion batteries by limiting Sn agglomeration

NASA Astrophysics Data System (ADS)

Wang, Wenhui; Shi, Liang; Lan, Danni; Li, Quan

2018-02-01

Flower-like SnS nanostructures are obtained by a simple solvothermal method for anode applications in Na-ion batteries. We show experimental evidence of progressive Sn agglomeration and crystalline Na2S enrichment at the end of de-sodiation process of the SnS electrode, both of which contribute to the capacity decay of the electrode upon repeated cycles. By replacing the commonly adopted acetylene black conductive additive with multi-wall carbon nanotubes (MWCNT), the cycle stability of the SnS electrode is largely improved, which correlates well with the observed suppression of both Sn agglomeration and Na2S enrichment at the end of de-sodiation cycle. A full cell is assembled with the SnS/MWCNT anode and the P2-Na2/3Ni1/3Mn1/2Ti1/6O2 cathode. An initial energy density of 262 Wh/kg (normalized to the total mass of cathode and anode) is demonstrated for the full cell, which retains 71% of the first discharge capacity after 40 cycles.

Structural and optical properties of tin disulphide thin films grown by flash evaporation

NASA Astrophysics Data System (ADS)

Banotra, Arun; Padha, Naresh

2018-04-01

Tin Disulphide thin films were deposited by Flash Evaporation method on corning Glass Substrate at different substrate temperatures. The deposited films were undertaken for Structural, Optical and compositional characterizations. Compositional analysis of the films exhibited decrease in the sulphur content enabling S/Sn ratio to vary from 2.05 to 1.32 with increasing substrate temperature. X-ray diffraction reveals amorphous nature of the as-deposited films with varying substrate temperatures. Optical measurements estimated from absorbance spectra suggest higher absorbance at λ≤500nm and higher transmission at λ≥500nm with bandgap changes from 2.45eV to 2.09eV. The 323K as-deposited films were undertaken for annealing which transforms the films into crystalline form corresponding to hexagonal SnS2 phase at 423K and above. However, the optical response for the annealed samples shows a higher transmission of 70% in the visible region which increases further in the Infrared region of the spectrum achieving maximum transmission upto 98%. This higher transmission in the Visible to Infrared region of the solar spectrum in amorphous as well as crystalline form makes the film suitable for their use as a window layer in the Solar Cell Design.

Photoelectrodes based on 2D opals assembled from Cu-delafossite double-shelled microspheres for an enhanced photoelectrochemical response.

PubMed

Oh, Yunjung; Yang, Wooseok; Tan, Jeiwan; Lee, Hyungsoo; Park, Jaemin; Moon, Jooho

2018-02-22

Although a unique light-harvesting property was recently demonstrated in a photocathode based on 2-dimensional (2D) opals of CuFeO 2 -shelled SiO 2 microspheres, the performance of a monolayer of ultra-thin CuFeO 2 -shelled microspheres is limited by ineffective charge separation. Herein, we propose an innovative design rule, in which an inner CuFeO 2 /outer CuAlO 2 double-shelled heterojunction is formed on each partially etched microsphere to obtain a hexagonally assembled 2D opal photoelectrode. Our Cu-delafossite double-shelled photocathode shows a dramatically improved charge separation capability, with a 9-fold increase in the photocurrent compared to that of the single-shelled counterpart. Electrochemical impedance spectroscopy clearly confirms the reduced charge transport/transfer resistance associated with the Cu-delafossite double-shelled photocathode, while surface photovoltage spectra reveal enhanced polarization of the photogenerated carrier, indicating improved charge separation capability with the aid of the heterojunction. Our finding sheds light on the importance of heterojunction interfaces in achieving optimal charge separation in opal architectures as well as the inner-shell/electrolyte interface to expedite charge separation/transport.

Exfoliated-SnS2 restacked on graphene as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries

NASA Astrophysics Data System (ADS)

Liu, Yongchang; Kang, Hongyan; Jiao, Lifang; Chen, Chengcheng; Cao, Kangzhe; Wang, Yijing; Yuan, Huatang

2015-01-01

Designed as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries, exfoliated-SnS2 restacked on graphene is prepared by the hydrolysis of lithiated SnS2 followed by a facile hydrothermal method. Structural and morphological characterizations demonstrate that ultrasmall SnS2 nanoplates (with a typical size of 20-50 nm) composed of 2-5 layers are homogeneously decorated on the surface of graphene, while the hybrid structure self-assembles into a three-dimensional (3D) network architecture. The obtained SnS2/graphene nanocomposite delivers a remarkable capacity as high as 650 mA h g-1 at a current density of 200 mA g-1. More impressively, the capacity can reach 326 mA h g-1 even at 4000 mA g-1 and remains stable at ~610 mA h g-1 without fading up to 300 cycles when the rate is brought back to 200 mA g-1. The excellent electrochemical performance is attributed to the synergetic effects between the ultrasmall SnS2 and the highly conductive graphene network. The unique structure can simultaneously facilitate Na+ ion diffusion, provide more reaction sites, and suppress aggregation and volume fluctuation of the active materials during prolonged cycling.Designed as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries, exfoliated-SnS2 restacked on graphene is prepared by the hydrolysis of lithiated SnS2 followed by a facile hydrothermal method. Structural and morphological characterizations demonstrate that ultrasmall SnS2 nanoplates (with a typical size of 20-50 nm) composed of 2-5 layers are homogeneously decorated on the surface of graphene, while the hybrid structure self-assembles into a three-dimensional (3D) network architecture. The obtained SnS2/graphene nanocomposite delivers a remarkable capacity as high as 650 mA h g-1 at a current density of 200 mA g-1. More impressively, the capacity can reach 326 mA h g-1 even at 4000 mA g-1 and remains stable at ~610 mA h g-1 without fading up to 300 cycles when the rate is brought back to 200 mA g-1. The excellent electrochemical performance is attributed to the synergetic effects between the ultrasmall SnS2 and the highly conductive graphene network. The unique structure can simultaneously facilitate Na+ ion diffusion, provide more reaction sites, and suppress aggregation and volume fluctuation of the active materials during prolonged cycling. Electronic supplementary information (ESI) available: Scheme S1, Fig. S1-S4. See DOI: 10.1039/c4nr05106h

Nonradiative Energy Transfer from Individual CdSe/ZnS Quantum Dots to Single-Layer and Few-Layer Tin Disulfide

DOE PAGES

Zang, Huidong; Routh, Prahlad K.; Huang, Yuan; ...

2016-03-31

We study the combination of zero-dimensional (0D) colloidal CdSe/ZnS quantum dots with tin disulfide (SnS 2), a two-dimensional (2D)-layered metal dichalcogenide, results in 0D–2D hybrids with enhanced light absorption properties. These 0D–2D hybrids, when exposed to light, exhibit intrahybrid nonradiative energy transfer from photoexcited CdSe/ZnS quantum dots to SnS 2. Using single nanocrystal spectroscopy, we find that the rate for energy transfer in 0D–2D hybrids increases with added number of SnS 2 layers, a positive manifestation toward the potential functionality of such 2D-based hybrids in applications such as photovoltaics and photon sensing.

Nonradiative Energy Transfer from Individual CdSe/ZnS Quantum Dots to Single-Layer and Few-Layer Tin Disulfide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zang, Huidong; Routh, Prahlad K.; Huang, Yuan

We study the combination of zero-dimensional (0D) colloidal CdSe/ZnS quantum dots with tin disulfide (SnS 2), a two-dimensional (2D)-layered metal dichalcogenide, results in 0D–2D hybrids with enhanced light absorption properties. These 0D–2D hybrids, when exposed to light, exhibit intrahybrid nonradiative energy transfer from photoexcited CdSe/ZnS quantum dots to SnS 2. Using single nanocrystal spectroscopy, we find that the rate for energy transfer in 0D–2D hybrids increases with added number of SnS 2 layers, a positive manifestation toward the potential functionality of such 2D-based hybrids in applications such as photovoltaics and photon sensing.

A SnS2-based photomemristor driven by sun

NASA Astrophysics Data System (ADS)

Dragoman, Mircea; Batiri, Mihail; Dinescu, Adrian; Ciobanu, Vladimir; Rusu, Emil; Dragoman, Daniela; Tiginyanu, Ion

2018-01-01

We demonstrate experimentally that a sample of a SnS2 layered semiconductor compound with the area of 1 cm2 and the thickness of 100 μm, contacted laterally by silver electrodes with the area of 1 mm2, acts naturally as a memristor device when illuminated by a sun simulator. Although the conductance of the device changes with the number of pulses or voltages sweeps, the current-voltage dependence is almost linear, showing only a very narrow but clearly pinched hysteresis, which is the main imprint of a memristor. This SnS2-based solid-state miniaturized photomemristor could be used for the implementation of all-optical neuromorphic circuits based on artificial neurons and synapses, oriented to learning algorithms of living organisms.

Single-Crystal Growth of Cl-Doped n-Type SnS Using SnCl2 Self-Flux.

PubMed

Iguchi, Yuki; Inoue, Kazutoshi; Sugiyama, Taiki; Yanagi, Hiroshi

2018-06-05

SnS is a promising photovoltaic semiconductor owing to its suitable band gap energy and high optical absorption coefficient for highly efficient thin film solar cells. The most significant carnage is demonstration of n-type SnS. In this study, Cl-doped n-type single crystals were grown using SnCl 2 self-flux method. The obtained crystal was lamellar, with length and width of a few millimeters and thickness ranging between 28 and 39 μm. X-ray diffraction measurements revealed the single crystals had an orthorhombic unit cell. Since the ionic radii of S 2- and Cl - are similar, Cl doping did not result in substantial change in lattice parameter. All the elements were homogeneously distributed on a cleaved surface; the Sn/(S + Cl) ratio was 1.00. The crystal was an n-type degenerate semiconductor with a carrier concentration of ∼3 × 10 17 cm -3 . Hall mobility at 300 K was 252 cm 2 V -1 s -1 and reached 363 cm 2 V -1 s -1 at 142 K.

n-type conversion of SnS by isovalent ion substitution: Geometrical doping as a new doping route

PubMed Central

Ran, Fan-Yong; Xiao, Zewen; Toda, Yoshitake; Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio

2015-01-01

Tin monosulfide (SnS) is a naturally p-type semiconductor with a layered crystal structure, but no reliable n-type SnS has been obtained by conventional aliovalent ion substitution. In this work, carrier polarity conversion to n-type was achieved by isovalent ion substitution for polycrystalline SnS thin films on glass substrates. Substituting Pb2+ for Sn2+ converted the majority carrier from hole to electron, and the free electron density ranged from 1012 to 1015 cm−3 with the largest electron mobility of 7.0 cm2/(Vs). The n-type conduction was confirmed further by the position of the Fermi level (EF) based on photoemission spectroscopy and electrical characteristics of pn heterojunctions. Density functional theory calculations reveal that the Pb substitution invokes a geometrical size effect that enlarges the interlayer distance and subsequently reduces the formation energies of Sn and Pb interstitials, which results in the electron doping. PMID:26020855

Online Social Networking and Addiction—A Review of the Psychological Literature

PubMed Central

Kuss, Daria J.; Griffiths, Mark D.

2011-01-01

Social Networking Sites (SNSs) are virtual communities where users can create individual public profiles, interact with real-life friends, and meet other people based on shared interests. They are seen as a ‘global consumer phenomenon’ with an exponential rise in usage within the last few years. Anecdotal case study evidence suggests that ‘addiction’ to social networks on the Internet may be a potential mental health problem for some users. However, the contemporary scientific literature addressing the addictive qualities of social networks on the Internet is scarce. Therefore, this literature review is intended to provide empirical and conceptual insight into the emerging phenomenon of addiction to SNSs by: (1) outlining SNS usage patterns, (2) examining motivations for SNS usage, (3) examining personalities of SNS users, (4) examining negative consequences of SNS usage, (5) exploring potential SNS addiction, and (6) exploring SNS addiction specificity and comorbidity. The findings indicate that SNSs are predominantly used for social purposes, mostly related to the maintenance of established offline networks. Moreover, extraverts appear to use social networking sites for social enhancement, whereas introverts use it for social compensation, each of which appears to be related to greater usage, as does low conscientiousness and high narcissism. Negative correlates of SNS usage include the decrease in real life social community participation and academic achievement, as well as relationship problems, each of which may be indicative of potential addiction. PMID:22016701

[Sincerity of effort: isokinetic evaluation of knee extension].

PubMed

Colombo, R; Demaiti, G; Sartorio, F; Orlandini, D; Vercelli, S; Ferriero, G

2008-01-01

The aim of this study was to find a reliable method to evaluate the sincerity of the muscular maximal effort performed in a dynamometric isokinetic test of knee flexion-extension. The coefficient of variation of the peak torque (CV) and 3 new indices were analysed: (1) the average coefficient of variation calculated on the complete peak torque curve (CVM); (2) the slope of the regression line in an endurance test (PRR); (3) the correlation coefficient of the peak torques in the same endurance test (CCR). Twenty healthy subjects underwent assessment in two different trials, maximal (MX) and 50% submaximal (SMX), with 20 minutes of rest between trials. Each trial consisted of 4 tests, each of 3 repetitions, at angular speed of 30, 180, 30, and 180 degrees/s, respectively, and 1 test of 15 repetitions at 240 degrees/s. Our findings confirmed the ability of CV to detect a high percentage of sincere efforts: at 30 degrees/s Sensibility (Sns)=100% and Specificity (Spc)=70%; at 180 degrees/s Sns=75%, Spc=95%. The 3 new indices here proposed showed high characteristics of Sns and Spc, generally better than those of CV. CVM showed at 180 degrees/s Sns=90% and Spc=100%, while at 30 degrees/s Sns=90%, Spc=75%. PRR was the best index identifying all the efforts, except one (Sns=100%, Spc=95%). The CCR coefficient showed Sns and Spc values both of 90%.

Online social networking and addiction--a review of the psychological literature.

PubMed

Kuss, Daria J; Griffiths, Mark D

2011-09-01

Social Networking Sites (SNSs) are virtual communities where users can create individual public profiles, interact with real-life friends, and meet other people based on shared interests. They are seen as a 'global consumer phenomenon' with an exponential rise in usage within the last few years. Anecdotal case study evidence suggests that 'addiction' to social networks on the Internet may be a potential mental health problem for some users. However, the contemporary scientific literature addressing the addictive qualities of social networks on the Internet is scarce. Therefore, this literature review is intended to provide empirical and conceptual insight into the emerging phenomenon of addiction to SNSs by: (1) outlining SNS usage patterns, (2) examining motivations for SNS usage, (3) examining personalities of SNS users, (4) examining negative consequences of SNS usage, (5) exploring potential SNS addiction, and (6) exploring SNS addiction specificity and comorbidity. The findings indicate that SNSs are predominantly used for social purposes, mostly related to the maintenance of established offline networks. Moreover, extraverts appear to use social networking sites for social enhancement, whereas introverts use it for social compensation, each of which appears to be related to greater usage, as does low conscientiousness and high narcissism. Negative correlates of SNS usage include the decrease in real life social community participation and academic achievement, as well as relationship problems, each of which may be indicative of potential addiction.

Evidence for a curvilinear relationship between sympathetic nervous system activation and women's physiological sexual arousal.

PubMed

Lorenz, Tierney Ahrold; Harte, Christopher B; Hamilton, Lisa Dawn; Meston, Cindy M

2012-01-01

There is increasing evidence that women's physiological sexual arousal is facilitated by moderate sympathetic nervous system (SNS) activation. Literature also suggests that the level of SNS activation may play a role in the degree to which SNS activity affects sexual arousal. We provide the first empirical examination of a possible curvilinear relationship between SNS activity and women's genital arousal using a direct measure of SNS activation in 52 sexually functional women. The relationship between heart rate variability (HRV), a specific and sensitive marker of SNS activation, and vaginal pulse amplitude (VPA), a measure of genital arousal, was analyzed. Moderate increases in SNS activity were associated with higher genital arousal, while very low or very high SNS activation was associated with lower genital arousal. These findings imply that there is an optimal level of SNS activation for women's physiological sexual arousal. Copyright © 2011 Society for Psychophysiological Research.

Ultrasonic synthesis of In-doped SnS nanoparticles and their physical properties

NASA Astrophysics Data System (ADS)

Jamali-Sheini, Farid; Cheraghizade, Mohsen; Yousefi, Ramin

2018-05-01

Indium (In)-doped Tin (II) Sulfide (SnS) nanoparticles (NPs) were synthesized by an ultra-sonication method and their optical, electrical, dielectric and photocatalytic properties were investigated. XRD patterns of the obtained NPs indicated formation of orthorhombic polycrystalline SnS. Field emission scanning electron microscopy exhibited flower-like NPs with particle sizes below 100 nm for both SnS and In-doped SnS samples. Optical analysis showed a decrease in energy band gap of SnS NPs upon In doping. In addition, electrical results demonstrated p-type nature of the synthesized SnS NPs and enhanced electrical conductivity of the NPs due to increased tin vacancy. Dielectric experiments on SnS NPs suggested an electronic polarizations effect to be responsible for changing dielectric properties of the particles, in terms of frequency. Finally, photocatalytic experiments revealed that high degradation power can be obtained using In-doped SnS NPs.

Increased yield pressure in the anal canal during sacral nerve stimulation: a pilot study with the functional lumen imaging probe.

PubMed

Haas, S; Liao, D; Gregersen, H; Lundby, L; Laurberg, S; Krogh, K

2017-02-01

Sacral nerve stimulation (SNS) is a well-established treatment for fecal incontinence but its mode of action remains obscure. Anal sphincter function is usually evaluated with manometry but resistance to distension may be a more appropriate parameter than luminal pressure. The functional lumen imaging probe allows detailed description of distension properties of the anal canal. Our objective in this study was to characterize the impact of SNS on distension properties of the anal canal in patients with idiopathic fecal incontinence. We studied 10 women (median age 64 [44-79] years) with idiopathic fecal incontinence at baseline and during SNS. The luminal geometry of the anal canal was examined with the FLIP at rest and during squeeze and the distensibility of the anal canal was investigated during filling of the bag. All patients were successfully treated with SNS and the mean Wexner Incontinence Score was reduced from 14.9 ± 4 to 7.1 ± 4.8 (P<.001). The pressure required to open the narrowest point of the anal canal during distension (yield pressure) increased from 14.5 ± 12.2 mmHg at baseline to 20.5 ± 13.3 mmHg during SNS (P<.01). The pressure-strain elastic modulus increased non-significantly from 2.2 ± 0.5 to 2.9 ± 1.6 kPa, indicating increased stiffness of the anal canal. The yield pressure and the resistance to distension increased in response to SNS for idiopathic fecal incontinence. This will inevitably increase the resistance to flow through the anal canal, which may contribute to the benefits of sacral nerve stimulation. © 2016 John Wiley & Sons Ltd.

Recurrent PAX3-MAML3 Fusion in Biphenotypic Sinonasal Sarcoma

PubMed Central

Wang, Xiaoke; Bledsoe, Krista L.; Graham, Rondell P.; Asmann, Yan W.; Viswanatha, David S.; Lewis, Jean E.; Lewis, Jason T.; Chou, Margaret M.; Yaszemski, Michael J.; Jen, Jin; Westendorf, Jennifer J.; Oliveira, André M.

2014-01-01

Biphenotypic sinonasal sarcoma (SNS) is a newly described tumor of the nasal and paranasal areas. Herein, we report the novel recurring chromosomal translocation t(2;4)(q35;q31.1) in SNS. The translocation results in the formation of the fusion protein PAX3-MAML3, which is a potent transcriptional activator of PAX3 response elements. The SNS phenotype is characterized by aberrant expression of genes involved in neuroectodermal and myogenic differentiation, which closely simulates the developmental roles of PAX3. PMID:24859338

The influence of social networking sites on health behavior change: a systematic review and meta-analysis

PubMed Central

Laranjo, Liliana; Arguel, Amaël; Neves, Ana L; Gallagher, Aideen M; Kaplan, Ruth; Mortimer, Nathan; Mendes, Guilherme A; Lau, Annie Y S

2015-01-01

Objective Our aim was to evaluate the use and effectiveness of interventions using social networking sites (SNSs) to change health behaviors. Materials and methods Five databases were scanned using a predefined search strategy. Studies were included if they focused on patients/consumers, involved an SNS intervention, had an outcome related to health behavior change, and were prospective. Studies were screened by independent investigators, and assessed using Cochrane's ‘risk of bias’ tool. Randomized controlled trials were pooled in a meta-analysis. Results The database search retrieved 4656 citations; 12 studies (7411 participants) met the inclusion criteria. Facebook was the most utilized SNS, followed by health-specific SNSs, and Twitter. Eight randomized controlled trials were combined in a meta-analysis. A positive effect of SNS interventions on health behavior outcomes was found (Hedges’ g 0.24; 95% CI 0.04 to 0.43). There was considerable heterogeneity (I2 = 84.0%; T2 = 0.058) and no evidence of publication bias. Discussion To the best of our knowledge, this is the first meta-analysis evaluating the effectiveness of SNS interventions in changing health-related behaviors. Most studies evaluated multi-component interventions, posing problems in isolating the specific effect of the SNS. Health behavior change theories were seldom mentioned in the included articles, but two particularly innovative studies used ‘network alteration’, showing a positive effect. Overall, SNS interventions appeared to be effective in promoting changes in health-related behaviors, and further research regarding the application of these promising tools is warranted. Conclusions Our study showed a positive effect of SNS interventions on health behavior-related outcomes, but there was considerable heterogeneity. Protocol registration The protocol for this systematic review is registered at http://www.crd.york.ac.uk/PROSPERO with the number CRD42013004140. PMID:25005606

Facile synthesis of gold nanomaterials with unusual crystal structures.

PubMed

Fan, Zhanxi; Huang, Xiao; Chen, Ye; Huang, Wei; Zhang, Hua

2017-11-01

Gold (Au) nanomaterials have attracted wide research attention, owing to their high chemical stability, promising catalytic properties, excellent biocompatibility, unique electronic structure and outstanding localized surface plasmon resonance (LSPR) absorption properties; all of which are closely related to their size and shape. Recently, crystal-phase-controlled synthesis of noble metal nanomaterials has emerged as a promising strategy to tune their physicochemical properties. This protocol describes the detailed experimental procedures for the crystal-phase-controlled syntheses of Au nanomaterials with unusual crystal structures under mild conditions. Briefly, pure hexagonal close-packed (hcp) Au square sheets (AuSSs) with a thickness of ∼2.4 nm are synthesized using a graphene-oxide-assisted method in which HAuCl 4 is reduced by oleylamine in a mixture of hexane and ethanol. By using pure hexane as the solvent, well-dispersed ultrathin hcp/face-centered cubic (fcc) Au nanowires with a diameter of ∼1.6 nm on graphene oxide can be obtained. Meanwhile, hcp/fcc Au square-like plates with a side length of 200-400 nm are prepared via the secondary growth of Au on the hcp AuSSs. Remarkably, hexagonal (4H) Au nanoribbons with a thickness of 2.0-6.0 nm can be synthesized with a one-pot colloidal method in which HAuCl 4 is reduced by oleylamine in a mixed solvent of hexane and 1,2-dichloropropane. It takes 17-37 h for the synthesis of these Au nanomaterials with unusual crystal structures. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used to characterize the resultant Au nanomaterials, which could have many promising applications, such as biosensing, near-IR photothermal therapy, catalysis and surface-enhanced Raman scattering (SERS).

Gender Differences in the Continuance of Online Social Networks

NASA Astrophysics Data System (ADS)

Shi, Na; Cheung, Christy M. K.; Lee, Matthew K. O.; Chen, Huaping

Social network sites (SNS) have become increasingly popular in the past few years benefiting from the rapid growth of Web 2.0 applications. However, research on the adoption and usage of SNS is limited. In this study, we attempt to understand users' continuance intention to use SNS and investigate the role of gender. A research model was developed and tested with 213 respondents from an online survey. The results confirm that users' continuance intention to use SNS is strongly determined by satisfaction. The effect of disconfirmation of maintaining offline contacts on satisfaction is more important for women, while the effect of disconfirmation of entertainment is more salient for men. Implications of this study for both researchers and practitioners are discussed.

The next evolution in radioguided surgery: breast cancer related sentinel node localization using a freehandSPECT-mobile gamma camera combination

PubMed Central

Engelen, Thijs; Winkel, Beatrice MF; Rietbergen, Daphne DD; KleinJan, Gijs H; Vidal-Sicart, Sergi; Olmos, Renato A Valdés; van den Berg, Nynke S; van Leeuwen, Fijs WB

2015-01-01

Accurate pre- and intraoperative identification of the sentinel node (SN) forms the basis of the SN biopsy procedure. Gamma tracing technologies such as a gamma probe (GP), a 2D mobile gamma camera (MGC) or 3D freehandSPECT (FHS) can be used to provide the surgeon with radioguidance to the SN(s). We reasoned that integrated use of these technologies results in the generation of a “hybrid” modality that combines the best that the individual radioguidance technologies have to offer. The sensitivity and resolvability of both 2D-MGC and 3D-FHS-MGC were studied in a phantom setup (at various source-detector depths and using varying injection site-to-SN distances), and in ten breast cancer patients scheduled for SN biopsy. Acquired 3D-FHS-MGC images were overlaid with the position of the phantom/patient. This augmented-reality overview image was then used for navigation to the hotspot/SN in virtual-reality using the GP. Obtained results were compared to conventional gamma camera lymphoscintigrams. Resolution of 3D-FHS-MGC allowed identification of the SNs at a minimum injection site (100 MBq)-to-node (1 MBq; 1%) distance of 20 mm, up to a source-detector depth of 36 mm in 2D-MGC and up to 24 mm in 3D-FHS-MGC. A clinically relevant dose of approximately 1 MBq was clearly detectable up to a depth of 60 mm in 2D-MGC and 48 mm in 3D-FHS-MGC. In all ten patients at least one SN was visualized on the lymphoscintigrams with a total of 12 SNs visualized. 3D-FHS-MGC identified 11 of 12 SNs and allowed navigation to all these visualized SNs; in one patient with two axillary SNs located closely to each other (11 mm), 3D-FHS-MGC was not able to distinguish the two SNs. In conclusion, high sensitivity detection of SNs at an injection site-to-node distance of 20 mm-and-up was possible using 3D-FHS-MGC. In patients, 3D-FHS-MGC showed highly reproducible images as compared to the conventional lymphoscintigrams. PMID:26069857

Preparation of SnS2 colloidal quantum dots and their application in organic/inorganic hybrid solar cells

PubMed Central

2011-01-01

Dispersive SnS2 colloidal quantum dots have been synthesized via hot-injection method. Hybrid photovoltaic devices based on blends of a conjugated polymer poly[2-methoxy-5-(3",7"dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) as electron donor and crystalline SnS2 quantum dots as electron acceptor have been studied. Photoluminescence measurement has been performed to study the surfactant effect on the excitons splitting process. The photocurrent of solar cells with the hybrid depends greatly on the ligands exchange as well as the device heat treatment. AFM characterization has demonstrated morphology changes happening upon surfactant replacement and annealing, which can explain the performance variation of hybrid solar cells. PMID:21711811

Multifunctional tunneling devices based on graphene/h-BN/MoSe2 van der Waals heterostructures

NASA Astrophysics Data System (ADS)

Cheng, Ruiqing; Wang, Feng; Yin, Lei; Xu, Kai; Ahmed Shifa, Tofik; Wen, Yao; Zhan, Xueying; Li, Jie; Jiang, Chao; Wang, Zhenxing; He, Jun

2017-04-01

The vertically stacked devices based on van der Waals heterostructures (vdWHs) of two-dimensional layered materials (2DLMs) have attracted considerable attention due to their superb properties. As a typical structure, graphene/hexagonal boron nitride (h-BN)/graphene vdWH has been proved possible to make tunneling devices. Compared with graphene, transition metal dichalcogenides possess intrinsic bandgap, leading to high performance of electronic devices. Here, tunneling devices based on graphene/h-BN/MoSe2 vdWHs are designed for multiple functions. On the one hand, the device shows a typical tunneling field-effect transistor behavior. A high on/off ratio of tunneling current (5 × 103) and an ultrahigh current rectification ratio (7 × 105) are achieved, which are attributed to relatively small electronic affinity of MoSe2 and optimized thickness of h-BN. On the other hand, the same structure also realizes 2D non-volatile memory with a high program/erase current ratio (>105), large memory window (˜150 V from ±90 V), and good retention characteristic. These results could enhance the fundamental understanding of tunneling behavior in vdWHs and contribute to the design of ultrathin rectifiers and memory based on 2DLMs.

Methodological issues in using data from social networking sites.

PubMed

Leng, Ho Keat

2013-09-01

Social networking sites (SNS) have become increasingly popular in recent years. With the amount of data available on SNS, the potential exists for researchers to use these data for their research. However, like any research method, there are limitations in using data from SNS. First, as members of SNS are not representative of the population, there is the limitation in generalizing the findings to the population. Second, in SNS with a low level of activity, there is also the issue of whether the data are sufficient for analysis. Third, the validity of the postings by members of SNS should be considered, as members of SNS may not be truthful in their responses. In addition, as the environment for SNS favors a quick emotive response as opposed to a cognitive response, the review suggests that the researcher will need to be aware of possibly different behavior when members of a SNS are faced with a high involvement decision. This article concludes that while there is potential in analyzing data from SNS, researchers should be aware of the limitations in using these data.

The unpredictability of lymphatic drainage from the ear in melanoma patients, and its implications for management.

PubMed

Peach, Howard S; van der Ploeg, Augustinus P T; Haydu, Lauren E; Stretch, Jonathan R; Shannon, Kerwin F; Uren, Roger F; Thompson, John F

2013-05-01

The ear is known to have variable lymphatic drainage. The purpose of this study was to define better the lymphatic drainage patterns of the ear by correlating the location of primary tumors, classified according to the embryologically derived anatomical subunits of the ear, with their mapped sentinel nodes (SNs) identified by lymphoscintigraphy (LS). Lymphatic drainage data for patients with a primary melanoma of the ear were reviewed and correlated with the precise primary melanoma site. Between 1993 and 2010, LS was performed in 111 patients with a primary melanoma on the ear, identifying 281 SNs in 195 lymph node (LN) fields. The mean numbers of SNs and LN fields identified by LS per patient were 2.65 and 1.76. SN biopsy was performed in 71 patients (64 %). The mean number of SNs removed was 2.36. The 111 ear melanomas were mostly located on the helical rim (55 %), followed by the lobule (24.3 %). The five different primary ear sites drained mainly to SNs in level CII, level CV and the preauricular region. Drainage was most often to level CII (36.4 %). Drainage to the contralateral neck was not observed. Lymphatic drainage of the ear has no predictable pattern and can be to SNs anywhere in the ipsilateral neck. Most commonly drainage is to cervical level II and the preauricular and postauricular LN fields. LS defines the lymphatic drainage pattern in individual melanoma patients and is essential for accurate SN identification and reliable SN biopsy.

Synthesis of SnS nanoparticles by SILAR method for quantum dot-sensitized solar cells.

PubMed

Tsukigase, Hiroki; Suzuki, Yoshikazu; Berger, Marie-Hélène; Sagawa, Takashi; Yoshikawa, Susumu

2011-03-01

SnS-sensitized TiO2 electrodes were applied in quantum dot-sensitized solar cells (QDSSCs) which are environmentally more favorable than conventional Cd or Pb-chalcogenide-sensitized electrodes. SnS nanoparticles were well-distributed over the surface of TiO2 nanoparticles by the successive ionic layer adsorption and reaction (SILAR) method. Deposited SnS nanoparticles had diameter about 3 nm. Under AM1.5 irradiation with 100 mW/cm2 light intensity (at 1 sun), the energy conversion efficiency of obtained cells reached a value of 0.21% (0.25 cm2) at SILAR coating cycles of 5. In addition, the photovoltaic performance was improved by additional ZnS coating on the surface of SnS-sensitized TiO2 electrodes.

High-T(sub c) Edge-geometry SNS Weak Links on Silicon-on-sapphire Substrates

NASA Technical Reports Server (NTRS)

Hunt, B.; Foote, M.; Pike, W.; Barner, J.; Vasquez, R.

1994-01-01

High-quality superconductor/normal-metal/superconductor(SNS) edge-geometry weak links have been produced on silicon-on-sapphire (SOS) substrates using a new SrTiO(sub 3)/'seed layer'/cubic-zirconia (YS2) buffer system.

H(-) ion source developments at the SNS.

PubMed

Welton, R F; Stockli, M P; Murray, S N; Pennisi, T R; Han, B; Kang, Y; Goulding, R H; Crisp, D W; Sparks, D O; Luciano, N P; Carmichael, J R; Carr, J

2008-02-01

The U.S. Spallation Neutron Source (SNS) will require substantially higher average and pulse H(-) beam currents than can be produced from conventional ion sources such as the base line SNS source. H(-) currents of 40-50 mA (SNS operations) and 70-100 mA (power upgrade project) with a rms emittance of 0.20-0.35pi mm mrad and a approximately 7% duty factor will be needed. We are therefore investigating several advanced ion source concepts based on rf plasma excitation. First, the performance characteristics of an external antenna source based on an Al(2)O(3) plasma chamber combined with an external multicusp magnetic configuration, an elemental Cs system, and plasma gun will be discussed. Second, the first plasma measurements of a helicon-driven H(-) ion source will also be presented.

Social networking site usage among childhood cancer survivors--a potential tool for research recruitment?

PubMed

Seltzer, Erica D; Stolley, Melinda R; Mensah, Edward K; Sharp, Lisa K

2014-09-01

The recent and rapid growth of social networking site (SNS) use presents a unique public health opportunity to develop effective strategies for the recruitment of hard-to-reach participants for cancer research studies. This survey investigated childhood cancer survivors' reported use of SNS such as Facebook or MySpace and their perceptions of using SNS, for recruitment into survivorship research. Sixty White, Black, and Hispanic adult childhood cancer survivors (range 18-48 years of age) that were randomly selected from a larger childhood cancer study, the Chicago Healthy Living Study, participated in this pilot survey. Telephone surveys were conducted to understand current SNS activity and attitudes towards using SNS as a cancer research recruitment tool. Seventy percent of participants reported SNS usage of which 80 % were at least weekly users and 79 % reported positive attitudes towards the use of SNS as a recruitment tool for survivorship research. The results of this pilot study revealed that SNS use was high and regular among the childhood cancer survivors sampled. Most had positive attitudes towards using SNS for recruitment of research. The results of this pilot survey suggest that SNS may offer an alternative approach for recruitment of childhood cancer survivors into research.

High-Performance All 2D-Layered Tin Disulfide: Graphene Photodetecting Transistors with Thickness-Controlled Interface Dynamics.

PubMed

Chang, Ren-Jie; Tan, Haijie; Wang, Xiaochen; Porter, Benjamin; Chen, Tongxin; Sheng, Yuewen; Zhou, Yingqiu; Huang, Hefu; Bhaskaran, Harish; Warner, Jamie H

2018-04-18

Tin disulfide crystals with layered two-dimensional (2D) sheets are grown by chemical vapor deposition using a novel precursor approach and integrated into all 2D transistors with graphene (Gr) electrodes. The Gr:SnS 2 :Gr transistors exhibit excellent photodetector response with high detectivity and photoresponsivity. We show that the response of the all 2D photodetectors depends upon charge trapping at the interface and the Schottky barrier modulation. The thickness-dependent SnS 2 measurements in devices reveal a transition from the interface-dominated response for thin crystals to bulklike response for the thicker SnS 2 crystals, showing the sensitivity of devices fabricated using layered materials on the number of layers. These results show that SnS 2 has photosensing performance when combined with Gr electrodes that is comparable to other 2D transition metal dichalcogenides of MoS 2 and WS 2 .

Shielding and Activation Analyses for BTF Facility at SNS

NASA Astrophysics Data System (ADS)

Popova, Irina; Gallmeier, Franz X.

2017-09-01

The beam test facility (BTF), which simulates front end of the Spallation Neutron Source (SNS), has been built at the SNS, and is preparing for commissioning. The BTF has been assembled and will operate in one of service buildings at the site. The 2.5 MeV proton beam, produced in the facility, will be stopped in the beam dump. In order to support BTF project from radiation protection site, neutronics simulations and activation analyses were performed to evaluate the necessary shielding around the facility and radionuclide inventory of the beam stop.

High-Resolution Tracking Asymmetric Lithium Insertion and Extraction and Local Structure Ordering in SnS2.

PubMed

Gao, Peng; Wang, Liping; Zhang, Yu-Yang; Huang, Yuan; Liao, Lei; Sutter, Peter; Liu, Kaihui; Yu, Dapeng; Wang, En-Ge

2016-09-14

In the rechargeable lithium ion batteries, the rate capability and energy efficiency are largely governed by the lithium ion transport dynamics and phase transition pathways in electrodes. Real-time and atomic-scale tracking of fully reversible lithium insertion and extraction processes in electrodes, which would ultimately lead to mechanistic understanding of how the electrodes function and why they fail, is highly desirable but very challenging. Here, we track lithium insertion and extraction in the van der Waals interactions dominated SnS2 by in situ high-resolution TEM method. We find that the lithium insertion occurs via a fast two-phase reaction to form expanded and defective LiSnS2, while the lithium extraction initially involves heterogeneous nucleation of intermediate superstructure Li0.5SnS2 domains with a 1-4 nm size. Density functional theory calculations indicate that the Li0.5SnS2 is kinetically favored and structurally stable. The asymmetric reaction pathways may supply enlightening insights into the mechanistic understanding of the underlying electrochemistry in the layered electrode materials and also suggest possible alternatives to the accepted explanation of the origins of voltage hysteresis in the intercalation electrode materials.

Fabrication of Cu2SnS3 thin films by ethanol-ammonium solution process by doctor-blade technique

NASA Astrophysics Data System (ADS)

Wang, Yaguang; Li, Jianmin; Xue, Cong; Zhang, Yan; Jiang, Guoshun; Liu, Weifeng; Zhu, Changfei

2017-11-01

In the present study, a low-cost and simple method is applied to fabricate Cu2SnS3 (CTS) thin films. Namely CTS thin films are prepared by a doctor-blade method with a slurry dissolving the Cu2O and SnS powders obtained from CBD reaction solution into ethanol-ammonium solvents. Series of characterization methods including XRD, Raman spectra, SEM and UV-Vis analyses are introduced to investigate the phase structure, morphology and optical properties of CTS thin films. As a result, monoclinic CTS films have been obtained with the disappearance of binary phases CuS and SnS2 while increasing the annealing temperature and time, high quality monoclinic CTS thin films consisting of compact and large grains have been successfully prepared by this ethanol-ammonium method. Moreover, the secondary phase Cu2Sn3S7 is also observed during the annealing process. In addition, the post-annealed CTS film with a band-gap about 0.89 eV shows excellent absorbance between 400 and 1200 nm, which is proper for the bottom layer in multi-junction thin film solar cells.[Figure not available: see fulltext.

Photocurrent Enhancement by a Rapid Thermal Treatment of Nanodisk-Shaped SnS Photocathodes.

PubMed

Patel, Malkeshkumar; Kumar, Mohit; Kim, Joondong; Kim, Yu Kwon

2017-12-21

Photocathodes made from the earth-abundant, ecofriendly mineral tin monosulfide (SnS) can be promising candidates for p/n-type photoelectrochemical cells because they meet the strict requirements of energy band edges for each individual photoelectrode. Herein we fabricated SnS-based cell that exhibited a prolonged photocurrent for 3 h at -0.3 V vs the reversible hydrogen electrode (RHE) in a 0.1 M HCl electrolyte. An enhancement of the cathodic photocurrent from 2 to 6 mA cm -2 is observed through a rapid thermal treatment. Mott-Schottky analysis of SnS samples revealed an anodic shift of 0.7 V in the flat band potential under light illumination. Incident photon-to-current conversion efficiency (IPCE) analysis indicates that an efficient charge transfer appropriate for solar hydrogen generation occurs at the -0.3 V vs RHE potential. This work shows that SnS is a promising material for photocathode in PEC cells and its performance can be enhanced via simple postannealing.

Coatable Li4 SnS4 Solid Electrolytes Prepared from Aqueous Solutions for All-Solid-State Lithium-Ion Batteries.

PubMed

Choi, Young Eun; Park, Kern Ho; Kim, Dong Hyeon; Oh, Dae Yang; Kwak, Hi Ram; Lee, Young-Gi; Jung, Yoon Seok

2017-06-22

Bulk-type all-solid-state lithium-ion batteries (ASLBs) for large-scale energy-storage applications have emerged as a promising alternative to conventional lithium-ion batteries (LIBs) owing to their superior safety. However, the electrochemical performance of bulk-type ASLBs is critically limited by the low ionic conductivity of solid electrolytes (SEs) and poor ionic contact between the active materials and SEs. Herein, highly conductive (0.14 mS cm -1 ) and dry-air-stable SEs (Li 4 SnS 4 ) are reported, which are prepared using a scalable aqueous-solution process. An active material (LiCoO 2 ) coated by solidified Li 4 SnS 4 from aqueous solutions results in a significant improvement in the electrochemical performance of ASLBs. Side-effects of the exposure of LiCoO 2 to aqueous solutions are minimized by using predissolved Li 4 SnS 4 solution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and magnetic properties of ultra-thin Fe films on metal-organic chemical vapour deposited GaN(0001)

NASA Astrophysics Data System (ADS)

Kim, Jun-Young; Ionescu, Adrian; Mansell, Rhodri; Farrer, Ian; Oehler, Fabrice; Kinane, Christy J.; Cooper, Joshaniel F. K.; Steinke, Nina-Juliane; Langridge, Sean; Stankiewicz, Romuald; Humphreys, Colin J.; Cowburn, Russell P.; Holmes, Stuart N.; Barnes, Crispin H. W.

2017-01-01

Structural and magnetic properties of 1-10 nm thick Fe films deposited on GaN(0001) were investigated. In-situ reflecting high energy electron diffraction images indicated a α-Fe(110)/GaN(0001) growth of the 3D Volmer-Weber type. The α-Fe(110) X-ray diffraction peak showed a 1° full-width at half-maximum, indicating ≈20 nm grain sizes. A significant reduction in Fe atomic moment from its bulk value was observed for films thinner than 4 nm. Both GaN/Fe interface roughness and Fe film coercivity increased with Fe thickness, indicating a possible deterioration of Fe crystalline quality. Magnetic anisotropy was mainly uniaxial for all films while hexagonal anisotropies appeared for thicknesses higher than 3.7 nm.

The effect of social networking sites on the relationship between perceived social support and depression.

PubMed

McDougall, Matthew A; Walsh, Michael; Wattier, Kristina; Knigge, Ryan; Miller, Lindsey; Stevermer, Michalene; Fogas, Bruce S

2016-12-30

This study examined whether Social Networking Sites (SNSs) have a negative moderator effect on the established relationship between perceived social support and depression in psychiatric inpatients. Survey instruments assessing for depression, perceived social support, and SNS use, were filled out by 301 psychiatric inpatients. Additional data on age, gender, and primary psychiatric diagnosis were collected. A step-wise multiple regression analysis was performed to determine significant interactions. There was no significant interaction of SNS use on the relationship between perceived social support and depression when measured by Social Media Use Integration Scale or by hours of SNS use per day. There was a significant negative relationship between perceived social support and depression, and a significant positive relationship between hours of SNS use per day and depression, measured by the Beck Depression Inventory-II. Limitations include a gender discrepancy among participants, generalizability, recall bias, and SNS measurement. This is the first study to look at SNS use and depression in psychiatric inpatients. SNS use did not affect perceived social support or the protective relationship between perceived social support and depression. Hours of SNS use per day were correlated with depression scores. Future studies between SNS use and depression should quantify daily SNS use. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Social Networking Site Usage Among Childhood Cancer Survivors - A Potential Tool for Research Recruitment?

PubMed Central

Seltzer, Erica D.; Stolley, Melinda R.; Mensah, Edward K.; Sharp, Lisa K.

2014-01-01

Purpose The recent and rapid growth of social networking site (SNS) use presents a unique public health opportunity to develop effective strategies for the recruitment of hard-to-reach participants for cancer research studies. This survey investigated childhood cancer survivors’ reported use of SNS such as facebook or MySpace and their perceptions of using SNS, for recruitment into survivorship research. Methods Sixty White, Black and Hispanic, adult childhood cancer survivors (range 18 – 48 years of age) that were randomly selected from a larger childhood cancer study, the Chicago Healthy Living Study (CHLS), participated in this pilot survey. Telephone surveys were conducted to understand current SNS activity and attitudes towards using SNS as a cancer research recruitment tool. Results Seventy percent of participants reported SNS usage of which 80% were at least weekly users and 79 % reported positive attitudes towards the use of SNS as a recruitment tool for survivorship research. Conclusions and implications for cancer survivors The results of this pilot study revealed that SNS use was high and regular among the childhood cancer survivors sampled. Most had positive attitudes towards using SNS for recruitment of research. The results of this pilot survey suggest that SNS may offer an alternative approach for recruitment of childhood cancer survivors into research. PMID:24532046

Comparison Analysis among Large Amount of SNS Sites

NASA Astrophysics Data System (ADS)

Toriumi, Fujio; Yamamoto, Hitoshi; Suwa, Hirohiko; Okada, Isamu; Izumi, Kiyoshi; Hashimoto, Yasuhiro

In recent years, application of Social Networking Services (SNS) and Blogs are growing as new communication tools on the Internet. Several large-scale SNS sites are prospering; meanwhile, many sites with relatively small scale are offering services. Such small-scale SNSs realize small-group isolated type of communication while neither mixi nor MySpace can do that. However, the studies on SNS are almost about particular large-scale SNSs and cannot analyze whether their results apply for general features or for special characteristics on the SNSs. From the point of view of comparison analysis on SNS, comparison with just several types of those cannot reach a statistically significant level. We analyze many SNS sites with the aim of classifying them by using some approaches. Our paper classifies 50,000 sites for small-scale SNSs and gives their features from the points of network structure, patterns of communication, and growth rate of SNS. The result of analysis for network structure shows that many SNS sites have small-world attribute with short path lengths and high coefficients of their cluster. Distribution of degrees of the SNS sites is close to power law. This result indicates the small-scale SNS sites raise the percentage of users with many friends than mixi. According to the analysis of their coefficients of assortativity, those SNS sites have negative values of assortativity, and that means users with high degree tend to connect users with small degree. Next, we analyze the patterns of user communication. A friend network of SNS is explicit while users' communication behaviors are defined as an implicit network. What kind of relationships do these networks have? To address this question, we obtain some characteristics of users' communication structure and activation patterns of users on the SNS sites. By using new indexes, friend aggregation rate and friend coverage rate, we show that SNS sites with high value of friend coverage rate activate diary postings and their comments. Besides, they become activated when hub users with high degree do not behave actively on the sites with high value of friend aggregation rate and high value of friend coverage rate. On the other hand, activation emerges when hub users behave actively on the sites with low value of friend aggregation rate and high value of friend coverage rate. Finally, we observe SNS sites which are increasing the number of users considerably, from the viewpoint of network structure, and extract characteristics of high growth SNS sites. As a result of discrimination on the basis of the decision tree analysis, we can recognize the high growth SNS sites with a high degree of accuracy. Besides, this approach suggests mixi and the other small-scale SNS sites have different character trait.

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

PubMed Central

Jaramillo, Rafael; Steinmann, Vera; Yang, Chuanxi; Hartman, Katy; Chakraborty, Rupak; Poindexter, Jeremy R.; Castillo, Mariela Lizet; Gordon, Roy; Buonassisi, Tonio

2015-01-01

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices. PMID:26067454

The influence of social networking sites on health behavior change: a systematic review and meta-analysis.

PubMed

Laranjo, Liliana; Arguel, Amaël; Neves, Ana L; Gallagher, Aideen M; Kaplan, Ruth; Mortimer, Nathan; Mendes, Guilherme A; Lau, Annie Y S

2015-01-01

Our aim was to evaluate the use and effectiveness of interventions using social networking sites (SNSs) to change health behaviors. Five databases were scanned using a predefined search strategy. Studies were included if they focused on patients/consumers, involved an SNS intervention, had an outcome related to health behavior change, and were prospective. Studies were screened by independent investigators, and assessed using Cochrane's 'risk of bias' tool. Randomized controlled trials were pooled in a meta-analysis. The database search retrieved 4656 citations; 12 studies (7411 participants) met the inclusion criteria. Facebook was the most utilized SNS, followed by health-specific SNSs, and Twitter. Eight randomized controlled trials were combined in a meta-analysis. A positive effect of SNS interventions on health behavior outcomes was found (Hedges' g 0.24; 95% CI 0.04 to 0.43). There was considerable heterogeneity (I(2) = 84.0%; T(2) = 0.058) and no evidence of publication bias. To the best of our knowledge, this is the first meta-analysis evaluating the effectiveness of SNS interventions in changing health-related behaviors. Most studies evaluated multi-component interventions, posing problems in isolating the specific effect of the SNS. Health behavior change theories were seldom mentioned in the included articles, but two particularly innovative studies used 'network alteration', showing a positive effect. Overall, SNS interventions appeared to be effective in promoting changes in health-related behaviors, and further research regarding the application of these promising tools is warranted. Our study showed a positive effect of SNS interventions on health behavior-related outcomes, but there was considerable heterogeneity. Protocol registration The protocol for this systematic review is registered at http://www.crd.york.ac.uk/PROSPERO with the number CRD42013004140. © The Author 2014. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.comFor numbered affiliations see end of article.

Comparison of dye doping and ultrathin emissive layer in white organic light-emitting devices with dual emissive layers

NASA Astrophysics Data System (ADS)

Wang, Xu; Qi, Yige; Yu, Junsheng

2014-09-01

White organic light-emitting devices (WOLEDs) with combined doping emissive layer (EML) and ultrathin EML have been fabricated to investigate the effect of each EML on the electroluminescent (EL) performance of the WOLEDs. Through tailoring doping concentration of bis[(4,6-difluorophenyl)-pyridinato-N,C2'](picolinate) iridium(III) (FIrpic) and thickness of ultrathin bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2'] iridium (acetylacetonate) [(tbt)2Ir(acac)] EML, it is found that the change in the doping ratio of FIrpic significantly influenced the EL efficiencies and spectra, while the alteration of ultrathin EML thickness had much milder effect on the EL performance. The results indicated that ultrathin EML is in favor of reproducibility in mass production compared with doping method.

A Review of HIV Prevention Studies that Use Social Networking Sites: Implications for Recruitment, Health Promotion Campaigns, and Efficacy Trials.

PubMed

Jones, Jamal; Salazar, Laura F

2016-11-01

This review describes the use of social networking sites (SNS) in the context of primary prevention of HIV. A review was conducted to assess the published literature for HIV interventions using SNS. Sixteen articles describing twelve interventions were included. SNS were instrumental in recruiting hard-to-reach populations within a short amount of time; were able to reach wide audiences beyond the targeted population for HIV prevention campaigns; and helped to significantly reduce sexual risk behaviors and increase HIV testing. SNS are a viable option to recruit hidden populations, engage the target audience, and disseminate HIV prevention messages. Researchers should use SNS to generate sampling frames that can be used to select participants. Practitioners should use SNS to post images of preventive behavior within health promotion campaigns. Researchers should use multiple SNS platforms to engage participants. As more studies are published using SNS for HIV prevention, meta-analyses will be needed.

SnS2 Thin Film Deposition by Spray Pyrolysis

NASA Astrophysics Data System (ADS)

Jaber, Abdallah Yahia; Alamri, Saleh Noaiman; Aida, Mohammed Salah

2012-06-01

Tin disulfide (SnS2) thin films have been synthesized using a simplified spray pyrolysis technique using a perfume atomizer. The films were deposited using two different solutions prepared by the dilution of SnCl2 and thiourea in distilled water and in methanol. The obtained films have a microcrystalline structure. The film deposited using methanol as the solvent is nearly stochiometric SnS2 with a spinel phase having a (001) preferential orientation. The film prepared with an aqueous solution is Sn-rich. Scanning electronic microscopy (SEM) images reveal that the film deposited with the aqueous solution is rough and is formed with large wires. However, the film deposited with methanol is dense and smooth. Conductivity measurements indicate that the aqueous solution leads to an n-type semiconductor, while methanol leads to a p-type semiconductor.

High-Performance Near-Infrared Photodetectors Based on p-type SnX (X=S, Se) Nanowires Grown via Chemical Vapor Deposition.

PubMed

Zheng, Dingshan; Fang, Hehai; Long, Mingsheng; Wu, Feng; Wang, Peng; Gong, Fan; Wu, Xing; Ho, Johnny C; Liao, Lei; Hu, Weida

2018-06-21

Because of the distinct electronic properties and strong interaction with light, quasi-one-dimensional nanowires (NWs) with semiconducting property have been demonstrated with tremendous potential for various technological applications, especially electronics and optoelectronics. However, until now, most of the state-of-the-art NW photodetectors are predominantly based on the N-type NW channel. Here, we successfully synthesized P-type SnSe and SnS NWs via chemical vapor deposition method and fabricated high-performance single SnSe and SnS NW photodetectors. Importantly, these two NW devices exhibit the impressive photodetection performance with the high photoconductive gain of 1.5 × 10 4 (2.8 × 10 4 ), good responsivity of 1.0× 10 4 A W -1 (1.6× 10 4 A W -1 ) as well as excellent detectivity of 3.3 × 10 12 Jones (2.4 × 10 12 Jones) under near-infrared illumination at a bias of 3 V for the SnSe NW (SnS NW) channel. The rise and fall times can be as efficient as 460 and 520 μs (1.2 and 15.1 ms), respectively, for the SnSe NW (SnS NW) device. Moreover, the spatially resolved photocurrent mapping of the devices further reveals the bias-dependent photocurrent generation. All these results evidently demonstrate that the P-type SnSe and SnS NWs have great potential to be applied in next-generation high-performance optoelectronic devices.

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).

Putting up emotional (Facebook) walls? Attachment status and emerging adults' experiences of social networking sites.

PubMed

Nitzburg, George C; Farber, Barry A

2013-11-01

Social networking sites (SNS) like Facebook can increase interpersonal connections but also intensify jealousy, envy, and surveillance behaviors. Attachment styles may help explain differences in experiencing SNS. This study investigated the role of attachment in influencing emerging adults' perceptions and feelings about SNS and their disclosures on SNS. Disorganized and anxious attachment predicted subjects' use of SNS to avoid more personal face-to-face communication, suggesting individuals with these tendencies use SNS to hold relationships at a psychological arm's distance. Anxious attachment also predicted feelings of intimacy when using SNS, perhaps reflecting online needs for comfort from others. A case narrative is presented to show how those with insecure attachment patterns may struggle to avoid interpersonal conflict when being continuously presented with ambiguous social information. © 2013 Wiley Periodicals, Inc.

The Relationship Between Use of Social Network Sites, Online Social Support, and Well-Being: Results From a Six-Wave Longitudinal Study.

PubMed

Utz, Sonja; Breuer, Johannes

2017-01-01

Existing work on the effects of social network sites (SNS) on well-being has often stressed that SNS can help people gain social support from their online networks, which positively affects their well-being. However, the majority of studies in this area have been cross-sectional in nature and/or relied on student samples. Using data from six waves of a longitudinal study with a representative sample of Dutch Internet users, we first examined whether users and nonusers of SNS differ in online social support and well-being (as indicated by life satisfaction and stress). In a second step, we investigated in more detail how SNS use - more specifically, asking for advice and the number of strong ties on these SNS - are related to online social support, stress, and satisfaction with life. Overall, our results provide no evidence for SNS use and online social support affecting either stress or life satisfaction. SNS users reported more online social support than nonusers did, but also higher levels of stress; the two groups did not differ in overall life satisfaction. With regard to the underlying processes, we found positive cross-sectional and longitudinal relationships between asking for advice on SNS and online social support, indicating that SNS can be an effective tool for receiving social support. However, online social support was not related to higher life satisfaction or reduced stress 6 months later; instead, it seems that SNS users with lower life satisfaction and/or higher stress seek more social support online by asking for advice on SNS.

The Relationship Between Use of Social Network Sites, Online Social Support, and Well-Being

PubMed Central

2017-01-01

Abstract. Existing work on the effects of social network sites (SNS) on well-being has often stressed that SNS can help people gain social support from their online networks, which positively affects their well-being. However, the majority of studies in this area have been cross-sectional in nature and/or relied on student samples. Using data from six waves of a longitudinal study with a representative sample of Dutch Internet users, we first examined whether users and nonusers of SNS differ in online social support and well-being (as indicated by life satisfaction and stress). In a second step, we investigated in more detail how SNS use – more specifically, asking for advice and the number of strong ties on these SNS – are related to online social support, stress, and satisfaction with life. Overall, our results provide no evidence for SNS use and online social support affecting either stress or life satisfaction. SNS users reported more online social support than nonusers did, but also higher levels of stress; the two groups did not differ in overall life satisfaction. With regard to the underlying processes, we found positive cross-sectional and longitudinal relationships between asking for advice on SNS and online social support, indicating that SNS can be an effective tool for receiving social support. However, online social support was not related to higher life satisfaction or reduced stress 6 months later; instead, it seems that SNS users with lower life satisfaction and/or higher stress seek more social support online by asking for advice on SNS. PMID:29147141

Beyond "Facebook Addiction": The Role of Cognitive-Related Factors and Psychiatric Distress in Social Networking Site Addiction.

PubMed

Pontes, Halley M; Taylor, Megan; Stavropoulos, Vasileios

2018-04-01

The use of social networking sites (SNSs) is rapidly increasing as billions of individuals use SNS platforms regularly to communicate with other users, follow the news, and play browser games. Given the widespread use of SNS platforms, investigating the potential predictors of addictive SNS use beyond Facebook use has become paramount given that most studies so far focused on "Facebook addiction." In this study, a total of 511 English-speaking SNS users (58.1% young adults aged 20-35 years; 64.6% female) were recruited online and asked to complete a battery of standardized psychometric tools assessing participants' sociodemographic characteristics, SNS preferences and patterns of use, SNS addiction, preference for online social interaction, maladaptive cognitions, fear of missing out (FoMo), dysfunctional emotion regulation, and general psychiatric distress. Overall, about 4.9% (n = 25) of all participants could be classed as having a high SNS addiction risk profile. Moreover, the results further indicated that FoMo (β = 0.38), maladaptive cognitions (β = 0.25), and psychiatric distress (β = 0.12) significantly predicted SNS addiction (i.e., p < 0.0001) and accounted for about 61% of the total variance in SNS addiction, with FoMo providing the strongest predictive contribution over and above the effects of sociodemographic variables and patterns of SNS use. The implications of the present findings were discussed in light of extant literature on behavioral addictions and Facebook addiction and further considerations were provided regarding the potential clinical implications for cognitive-based psychological treatment approaches to SNS addiction.

Band edge states, intrinsic defects, and dopants in monolayer HfS2 and SnS2

NASA Astrophysics Data System (ADS)

Lu, Haichang; Guo, Yuzheng; Robertson, John

2018-02-01

Although monolayer HfS2 and SnS2 do not have a direct bandgap like MoS2, they have much higher carrier mobilities. Their band offsets are favorable for use with WSe2 in tunnel field effect transistors. Here, we study the effective masses, intrinsic defects, and substitutional dopants of these dichalcogenides. We find that HfS2 has surprisingly small effective masses for a compound that might appear partly ionic. The S vacancy in HfS2 is found to be a shallow donor while that in SnS2 is a deep donor. Substitutional dopants at the S site are found to be shallow. This contrasts with MoS2 where donors and acceptors are not always shallow or with black phosphorus where dopants can reconstruct into deep non-doping configurations. It is pointed out that HfS2 is more favorable than MoS2 for semiconductor processing because it has the more convenient CVD precursors developed for growing HfO2.

How do general practice residents use social networking sites in asynchronous distance learning?

PubMed

Maisonneuve, Hubert; Chambe, Juliette; Lorenzo, Mathieu; Pelaccia, Thierry

2015-09-21

Blended learning environments - involving both face-to-face and remote interactions - make it easier to adapt learning programs to constraints such as residents' location and low teacher-student ratio. Social networking sites (SNS) such as Facebook®, while not originally intended to be used as learning environments, may be adapted for the distance-learning part of training programs. The purpose of our study was to explore the use of SNS for asynchronous distance learning in a blended learning environment as well as its influence on learners' face-to-face interactions. We conducted a qualitative study and carried out semi-structured interviews. We performed purposeful sampling for maximal variation to include eight general practice residents in 2(nd) and 3(rd) year training. A thematic analysis was performed. The social integration of SNS facilitates the engagement of users in their learning tasks. This may also stimulate students' interactions and group cohesion when members meet up in person. Most of the general practice residents who work in the blended learning environment we studied had a positive appraisal on their use of SNS. In particular, we report a positive impact on their engagement in learning and their participation in discussions during face-to-face instruction. Further studies are needed in order to evaluate the effectiveness of SNS in blended learning environments and the appropriation of SNS by teachers.

Ultrathin Coating of Confined Pt Nanocatalysts by Atomic Layer Deposition for Enhanced Catalytic Performance in Hydrogenation Reactions.

PubMed

Wang, Meihua; Gao, Zhe; Zhang, Bin; Yang, Huimin; Qiao, Yan; Chen, Shuai; Ge, Huibin; Zhang, Jiankang; Qin, Yong

2016-06-13

Metal-support interfaces play a prominent role in heterogeneous catalysis. However, tailoring the metal-support interfaces to realize full utilization remains a major challenge. In this work, we propose a graceful strategy to maximize the metal-oxide interfaces by coating confined nanoparticles with an ultrathin oxide layer. This is achieved by sequential deposition of ultrathin Al2 O3 coats, Pt, and a thick Al2 O3 layer on carbon nanocoils templates by atomic layer deposition (ALD), followed by removal of the templates. Compared with the Pt catalysts confined in Al2 O3 nanotubes without the ultrathin coats, the ultrathin coated samples have larger Pt-Al2 O3 interfaces. The maximized interfaces significantly improve the activity and the protecting Al2 O3 nanotubes retain the stability for hydrogenation reactions of 4-nitrophenol. We believe that applying ALD ultrathin coats on confined catalysts is a promising way to achieve enhanced performance for other catalysts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental and Theoretical Investigations on Intermediate Band in Doped Nano-SnS2

NASA Astrophysics Data System (ADS)

Heiba, Zein K.; Mohamed, Mohamed Bakr; Abdel Kader, M. H.

2018-03-01

Nano-SnS2 and Sn0.75 X 0.25S2 (X = Cr, Fe, Y) have been prepared by thermolysis method. Phase analysis of x-ray diffraction data confirmed the single-phase nature of all prepared samples, with some residual carbon contributing to the background. Rietveld refinement revealed high anisotropy in crystallite size, signifying a cylindrical structure for the particle shape, as confirmed by transmission electron microscopy. The refined occupancies obtained for the doped cations were found to be smaller than the nominal target doping ratio (25%). Fourier-transform infrared spectra showed presence of Sn-S bond in all samples. The energy was found to be 3.42 eV, 3.33 eV, 2.1 eV and 3.14 eV, and 3.62 eV for undoped SnS2 and when doped with Cr, Fe, and Y, respectively. Density functional theory calculations illustrated that Fe-doped SnS2 has two bandgaps [normal and intermediate (IB) bands]. Meanwhile, Sn0.75Fe0.25S2 sample showed anti-Stokes and an extra photoluminescence peak related to the newly created intermediate band (IB) inside the energy gap. On the other hand, pure SnS2 and Sn0.75 X 0.25S2 (X = Cr, Y) samples emitted four photoluminescence subspectra in ultraviolet, violet, and blue regions.

Generalized Self-Doping Engineering towards Ultrathin and Large-Sized Two-Dimensional Homologous Perovskites.

PubMed

Chen, Junnian; Wang, Yaguang; Gan, Lin; He, Yunbin; Li, Huiqiao; Zhai, Tianyou

2017-11-20

Two-dimensional (2D) homologous perovskites are arousing intense interest in photovoltaics and light-emitting fields, attributing to significantly improved stability and increasing optoelectronic performance. However, investigations on 2D homologous perovskites with ultrathin thickness and large lateral dimension have been seldom reported, being mainly hindered by challenges in synthesis. A generalized self-doping directed synthesis of ultrathin 2D homologous (BA) 2 (MA) n-1 Pb n Br 3n+1 (1

Spallation radiation effects in materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mansur, L.K.; Farrell, K.; Wechsler, M.S.

1996-06-01

Spallation refers to the process whereby particles (chiefly neutrons) are ejected from nuclei upon bombardment by high-energy protons. Spallation neutron sources (SNS`s) use these neutrons for neutron scattering and diffraction research, and SNS`s are proposed as the basis for systems for tritium production and transmutation of nuclear waste. Materials in SNS`s are exposed to the incident proton beam (energies typically about 1000 MeV) and to the spallation neutrons (spectrum of energies extending up to about 1000 MeV). By contrast the fission neutrons in nuclear reactors have an average energy of only about 2 MeV, and the neutrons in fusion reactorsmore » would have energies below about 14 MeV. Furthermore, the protons and neutrons in SNS`s for scattering and diffraction research are pulsed at frequencies of about 10 to 60 Hz, from which significant changes in the kinetics of point and extended defects may be expected. In addition, much higher transmutation rates occur in SNS-irradiated materials, On the whole, then, significant differences in microstructural development and macroscopic properties may result upon exposure in SNS systems, as compared with fission and fusion irradiations. In a more general sense, subjecting materials to new radiation environments has almost routinely led to new discoveries. To the extent that data are avaiable, however, the spallation environment appears to increase the degree of damage without introducing totally new effects. The first part of this presentation is an overview of radiation effects in materials, outlining essential concepts and property changes and their physical bases. This background is followed by a description of SNS irradiation environments and the effects on materials of exposure to these environments. A special discussion is given of the selection of target (e.g., liquid mercury), container (e.g., austenitic stainless steel or ferritic/martensitic steel), and structural materials in SNS systems.« less

Ultrathin TiO(x) films on Pt(111): a LEED, XPS, and STM investigation.

PubMed

Sedona, Francesco; Rizzi, Gian Andrea; Agnoli, Stefano; Llabrés i Xamena, Francesc X; Papageorgiou, Anthoula; Ostermann, Dieter; Sambi, Mauro; Finetti, Paola; Schierbaum, Klaus; Granozzi, Gaetano

2005-12-29

Ultrathin ordered titanium oxide films on Pt(111) surface are prepared by reactive evaporation of Ti in oxygen. By varying the Ti dose and the annealing conditions (i.e., temperature and oxygen pressure), six different long-range ordered phases are obtained. They are characterized by means of low-energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). By careful optimization of the preparative parameters, we find conditions where predominantly single phases of TiO(x), revealing distinct LEED pattern and STM images, are produced. XPS binding energy and photoelectron diffraction (XPD) data indicate that all the phases, except one (the stoichiometric rect-TiO2), are one monolayer thick and composed of a Ti-O bilayer with interfacial Ti. Atomically resolved STM images confirm that these TiO(x) phases wet the Pt surface, in contrast to rect-TiO2. This indicates their interface stabilization. At a low Ti dose (0.4 monolayer equivalents, MLE), an incommensurate kagomé-like low-density phase (k-TiO(x) phase) is observed where hexagons are sharing their vertexes. At a higher Ti dose (0.8 MLE), two denser phases are found, both characterized by a zigzag motif (z- and z'-TiO(x) phases), but with distinct rectangular unit cells. Among them, z'-TiO(x), which is obtained by annealing in ultrahigh vacuum (UHV), shows a larger unit cell. When the postannealing of the 0.8 MLE deposit is carried out at high temperatures and high oxygen partial pressures, the incommensurate nonwetting, fully oxidized rect-TiO2 is found The symmetry and lattice dimensions are almost identical with rect-VO2, observed in the system VO(x)/Pd(111). At a higher coverage (1.2 MLE), two commensurate hexagonal phases are formed, namely the w- [(square root(43) x square root(43)) R 7.6 degrees] and w'-TiO(x) phase [(7 x 7) R 21.8 degrees]. They show wagon-wheel-like structures and have slightly different lattice dimensions. Larger Ti deposits produce TiO2 nanoclusters on top of the different monolayer films, as supported both by XPS and STM data. Besides the formation of TiO(x) surfaces phases, wormlike features are found on the bare parts of the substrate by STM. We suggest that these structures, probably multilayer disordered TiO2, represent growth precursors of the ordered phases. Our results on the different nanostructures are compared with literature data on similar systems, e.g., VO(x)/Pd(111), VO(x)/Rh(111), TiO(x)/Pd(111), TiO(x)/Pt(111), and TiO(x)/Ru(0001). Similar and distinct features are observed in the TiO(x)/Pt(111) case, which may be related to the different chemical natures of the overlayer and of the substrate.

How does personality matter? An investigation of the impact of extraversion on individuals' SNS use.

PubMed

Deng, Shengli; Liu, Yong; Li, Hongxiu; Hu, Feng

2013-08-01

The fast proliferation of social networking sites (SNS) offers Internet users new possibilities for developing and maintaining their social network. Despite a growing interest in SNS, less research attention has been paid to SNS usage from the perspective of personality, that is, the Big Five personality traits. This study develops a model to elucidate how extraversion, an important dimension of personality, affects the perceptions of SNS users and their continuance intention. The research model is empirically tested with answers gained from 221 usable questionnaires. The results indicate that extraversion positively affects perceived satisfaction, supplementary entertainment, and critical mass directly, and indirectly influences both playfulness and SNS continuance intention.

Online social networking services in the management of patients with diabetes mellitus: systematic review and meta-analysis of randomised controlled trials.

PubMed

Toma, Tania; Athanasiou, Thanos; Harling, Leanne; Darzi, Ara; Ashrafian, Hutan

2014-11-01

Social networking services (SNS) can facilitate real-time communication and feedback of blood glucose and other physiological data between patients and healthcare professionals. This systematic review and meta-analysis aims to summarise the current evidence surrounding the role of online social networking services in diabetes care. We performed a systematic literature review of the Medline, EMBASE and PsychINFO databases of all studies reporting HbA1c (glycated haemoglobin) as a measure of glycaemic control for social networking services in diabetes care. HbA1c, clinical outcomes and the type of technology used were extracted. Study quality and publication bias were assessed. SNS interventions beneficially reduced HbA1c when compared to controls, which was confirmed by sensitivity analysis. SNS interventions also significantly improved systolic and diastolic blood pressure, triglycerides and total cholesterol. Subgroup analysis according to diabetes type demonstrated that Type 2 diabetes patients had a significantly greater reduction in HbA1c than those with Type 1 diabetes. Online SNS provide a novel, feasible approach to improving glycaemic control, particularly in patients with Type 2 diabetes. Further mechanistic and cost-effectiveness studies are required to improve our understanding of SNS and its efficacy in diabetes care. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The pervasiveness, connectedness, and intrusiveness of social network site use among young adolescents.

PubMed

Espinoza, Guadalupe; Juvonen, Jaana

2011-12-01

Young adolescents are quickly becoming avid users of social networking sites (SNSs); however, little is known regarding how they use these sites. The goal of the present study was to examine the extent to which young adolescents use SNSs, with whom they connect via these sites, and whether SNS use disrupts daily functioning. Among 268 middle-school students surveyed, 63% reported having their own profile page on an SNS. On average, adolescents reported having 196 SNS contacts (friends), most of whom were known peers. Young adolescents with an SNS spent most of their time viewing and responding to comments written on their profile page. Among the SNS users, 39% reported getting behind on schoolwork and 37% reported losing sleep at least once because they were visiting an SNS. As SNS use becomes embedded in young teens' daily lives, it is important to better understand how such use affects their daily adaptive functioning.

First comes social networking, then comes marriage? Characteristics of Americans married 2005-2012 who met through social networking sites.

PubMed

Hall, Jeffrey A

2014-05-01

Abstract Although social networking sites (SNS) have become increasingly prevalent and integrated into the lives of users, the role of SNS in courtship is relatively unknown. The present manuscript reports on the characteristics of Americans married between 2005 and 2012 who met through SNS drawn from a weighted national sample (N=18,527). Compared to other online meetings (i.e., dating sites, online communities, one-on-one communication), individuals who met through SNS were younger, married more recently, and were more likely to be African American. Compared with offline meetings, individuals who met through SNS were more likely to be younger, male, African American and Hispanic, married more recently, and frequent Internet users with higher incomes. Trends suggest an increasing proportion of individuals are meeting using SNS, necessitating further research on factors that influence romantic relational development through SNS.

The use of social networking sites for relationship maintenance in long-distance and geographically close romantic relationships.

PubMed

Billedo, Cherrie Joy; Kerkhof, Peter; Finkenauer, Catrin

2015-03-01

Social networking sites (SNS) play an increasingly important role in maintaining geographically close romantic relationships (GCRR). However, knowledge about SNS use in long-distance romantic relationships (LDRR) is still lacking. The present study examined the relative importance of SNS in maintaining LDRR compared to GCRR, particularly with regard to the use of SNS to express involvement (via relational maintenance behaviors) and to gauge a partner's involvement (via partner surveillance and jealousy) in the relationship. An online survey was conducted among predominantly young adult Facebook users who were in a romantic relationship (N=272). Results showed that participants who were in a LDRR reported higher levels of relational maintenance behaviors through SNS than participants who were in a GCRR. Also, as compared to participants who were in a GCRR, participants who were in a LDRR used SNS more for partner surveillance and experienced higher levels of SNS jealousy.

Magnetotransport Properties in High-Quality Ultrathin Two-Dimensional Superconducting Mo2C Crystals.

PubMed

Wang, Libin; Xu, Chuan; Liu, Zhibo; Chen, Long; Ma, Xiuliang; Cheng, Hui-Ming; Ren, Wencai; Kang, Ning

2016-04-26

Ultrathin transition metal carbides are a class of developing two-dimensional (2D) materials with superconductivity and show great potentials for electrical energy storage and other applications. Here, we report low-temperature magnetotransport measurements on high-quality ultrathin 2D superconducting α-Mo2C crystals synthesized by a chemical vapor deposition method. The magnetoresistance curves exhibit reproducible oscillations at low magnetic fields for temperature far below the superconducting transition temperature of the crystals. We interpret the oscillatory magnetoresistance as a consequence of screening currents circling around the boundary of triangle-shaped terraces found on the surface of ultrathin Mo2C crystals. As the sample thickness decreases, the Mo2C crystals exhibit negative magnetoresistance deep in the superconducting transition regime, which reveals strong phase fluctuations of the superconducting order parameters associated with the superconductor-insulator transition. Our results demonstrate that the ultrathin superconducting Mo2C crystals provide an interesting system for studying rich transport phenomena in a 2D crystalline superconductor with enhanced quantum fluctuations.

Cortisol and Children's Adjustment: The Moderating Role of Sympathetic Nervous System Activity

ERIC Educational Resources Information Center

El-Sheikh, Mona; Erath, Stephen A.; Buckhalt, Joseph A.; Granger, Douglas A.; Mize, Jacquelyn

2008-01-01

We examined relations among cortisol, markers of sympathetic nervous system (SNS) activity (including salivary alpha-amylase and skin conductance level), and children's adjustment. We also tested the Bauer et al. ("Journal of Developmental and Behavioral Pediatrics," 23(2), 102-113, 2002) hypothesis that interactions between the SNS and cortisol…

One-step growth of thin film SnS with large grains using MOCVD.

PubMed

Clayton, Andrew J; Charbonneau, Cecile M E; Tsoi, Wing C; Siderfin, Peter J; Irvine, Stuart J C

2018-01-01

Thin film tin sulphide (SnS) films were produced with grain sizes greater than 1 μm using a one-step metal organic chemical vapour deposition process. Tin-doped indium oxide (ITO) was used as the substrate, having a similar work function to molybdenum typically used as the back contact, but with potential use of its transparency for bifacial illumination. Tetraethyltin and ditertiarybutylsulphide were used as precursors with process temperatures 430-470 °C to promote film growth with large grains. The film stoichiometry was controlled by varying the precursor partial pressure ratios and characterised with energy dispersive X-ray spectroscopy to optimise the SnS composition. X-ray diffraction and Raman spectroscopy were used to determine the phases that were present in the film and revealed that small amounts of ottemannite Sn 2 S 3 was present when SnS was deposited on to the ITO using optimised growth parameters. Interaction at the SnS/ITO interface to form Sn 2 S 3 was deduced to have resulted for all growth conditions.

Active bialkali photocathodes on free-standing graphene substrates

DOE PAGES

Yamaguchi, Hisato; Liu, Fangze; DeFazio, Jeffrey; ...

2017-06-01

Here, the hexagonal structure of graphene gives rise to the property of gas impermeability, motivating its investigation for a new application: protection of semiconductor photocathodes in electron accelerators. These materials are extremely susceptible to degradation in efficiency through multiple mechanisms related to contamination from the local imperfect vacuum environment of the host photoinjector. Few-layer graphene has been predicted to permit a modified photoemission response of protected photocathode surfaces, and recent experiments of single-layer graphene on copper have begun to confirm these predictions for single crystal metallic photocathodes. Unlike metallic photoemitters, the integration of an ultra-thin graphene barrier film with conventionalmore » semiconductor photocathode growth processes is not straightforward. A first step toward addressing this challenge is the growth and characterization of technologically relevant, high quantum efficiency bialkali photocathodes on ultra-thin free-standing graphene substrates. Photocathode growth on free-standing graphene provides the opportunity to integrate these two materials and study their interaction. Specifically, spectral response features and photoemission stability of cathodes grown on graphene substrates are compared to those deposited on established substrates. In addition, we observed an increase of work function for the graphene encapsulated bialkali photocathode surfaces, which is predicted by our calculations. The results provide a unique demonstration of bialkali photocathodes on free-standing substrates, and indicate promise towards our goal of fabricating high-performance graphene encapsulated photocathodes with enhanced lifetime for accelerator applications.« less

Active bialkali photocathodes on free-standing graphene substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamaguchi, Hisato; Liu, Fangze; DeFazio, Jeffrey

Here, the hexagonal structure of graphene gives rise to the property of gas impermeability, motivating its investigation for a new application: protection of semiconductor photocathodes in electron accelerators. These materials are extremely susceptible to degradation in efficiency through multiple mechanisms related to contamination from the local imperfect vacuum environment of the host photoinjector. Few-layer graphene has been predicted to permit a modified photoemission response of protected photocathode surfaces, and recent experiments of single-layer graphene on copper have begun to confirm these predictions for single crystal metallic photocathodes. Unlike metallic photoemitters, the integration of an ultra-thin graphene barrier film with conventionalmore » semiconductor photocathode growth processes is not straightforward. A first step toward addressing this challenge is the growth and characterization of technologically relevant, high quantum efficiency bialkali photocathodes on ultra-thin free-standing graphene substrates. Photocathode growth on free-standing graphene provides the opportunity to integrate these two materials and study their interaction. Specifically, spectral response features and photoemission stability of cathodes grown on graphene substrates are compared to those deposited on established substrates. In addition, we observed an increase of work function for the graphene encapsulated bialkali photocathode surfaces, which is predicted by our calculations. The results provide a unique demonstration of bialkali photocathodes on free-standing substrates, and indicate promise towards our goal of fabricating high-performance graphene encapsulated photocathodes with enhanced lifetime for accelerator applications.« less

A systematic review of social networking sites: innovative platforms for health research targeting adolescents and young adults.

PubMed

Park, Bu Kyung; Calamaro, Christina

2013-09-01

To review the evidence to determine if social networking sites (SNS) are effective tools for health research in the adolescent and young adult populations. Systematic review of published research articles focused on use of SNS for youth health research. Seventeen articles were selected that met the following criteria: used SNS at any stage of study, participants between 13 and 25 years of age, English language, and both international and national studies. Reviewers categorized selected studies based on the way SNS were used. Utilization of SNS for effectively implementing research with adolescents and young adults include (a) recruitment, (b) intervention, and (c) measurement. Four findings about advantages of using SNS apparent in this review are (a) ease of access to youth, (b) cost effectiveness in recruitment, (c) ease of intervention, and (d) reliable screening venue of mental status and high-risk behaviors. Although this literature review showed relatively minimal research to date on the use of SNS for research targeting adolescents and young adults, the impact of using SNS for health research is of considerable importance for researchers as well as participants. With careful focus, SNS can become a valuable platform to access, recruit, and deliver health interventions in a cost-effective manner to youth populations as well as hard-to-reach minority or underserved populations. The evidence demonstrates the usefulness of SNS as innovative platforms for health promotion among adolescents and young adults. © 2013 Sigma Theta Tau International.

Second Neoplasms in Survivors of Childhood Cancer: Findings From the Childhood Cancer Survivor Study Cohort

PubMed Central

Meadows, Anna T.; Friedman, Debra L.; Neglia, Joseph P.; Mertens, Ann C.; Donaldson, Sarah S.; Stovall, Marilyn; Hammond, Sue; Yasui, Yutaka; Inskip, Peter D.

2009-01-01

Purpose To review the reports of subsequent neoplasms (SNs) in the Childhood Cancer Survivor Study (CCSS) cohort that were made through January 1, 2006, and published before July 31, 2008, and to discuss the host-, disease-, and therapy-related risk factors associated with SNs. Patients and Methods SNs were ascertained by survivor self-reports and subsequently confirmed by pathology findings or medical record review. Cumulative incidence of SNs and standardized incidence ratios for second malignant neoplasms (SMNs) were calculated. The impact of host-, disease-, and therapy-related risk factors was evaluated by Poisson regression. Results Among 14,358 cohort members, 730 reported 802 SMNs (excluding nonmelanoma skin cancers). This represents a 2.3-fold increase in the number of SMNs over that reported in the first comprehensive analysis of SMNs in the CCSS cohort, which was done 7 years ago. In addition, 66 cases of meningioma and 1,007 cases of nonmelanoma skin cancer were diagnosed. The 30-year cumulative incidence of SMNs was 9.3% and that of nonmelanoma skin cancer was 6.9%. Risk of SNs remains elevated for more than 20 years of follow-up for all primary childhood cancer diagnoses. In multivariate analyses, risks differ by SN subtype, but include radiotherapy, age at diagnosis, sex, family history of cancer, and primary childhood cancer diagnosis. Female survivors whose primary childhood cancer diagnosis was Hodgkin's lymphoma or sarcoma and who received radiotherapy are at particularly increased risk. Analyses of risk associated with radiotherapy demonstrated different dose-response curves for specific SNs. Conclusion Childhood cancer survivors are at a substantial and increasing risk for SNs, including nonmelanoma skin cancer and meningiomas. Health care professionals should understand the magnitude of these risks to provide individuals with appropriate counseling and follow-up. PMID:19255307

Associations between the use of social networking sites and unhealthy eating behaviours and excess body weight in adolescents.

PubMed

Sampasa-Kanyinga, Hugues; Chaput, Jean-Philippe; Hamilton, Hayley A

2015-12-14

Unhealthy eating behaviour and excess body weight have been related to sedentary behaviour, particularly screen time, in adolescents; however, little is known about their associations with the use of social networking sites (SNS). We investigated the associations between time spent using SNS and unhealthy eating behaviours (including breakfast skipping, consumption of sugar-sweetened beverages (SSB) and energy drinks) and body weight in adolescents. Data on 9858 students (mean age: 15·2 (SD 1·9) years) in grades 7 through 12 were derived from the 2013 cycle of the Ontario Student Drug Use and Health Survey--a cross-sectional school-based survey of middle and high school students. The majority (81·5%) of students reported daily use of SNS and an additional 10·7% reported using them on an irregular basis. Multivariate logistic regression analyses revealed that the use of SNS was associated with increased odds of skipping breakfast (P trend<0·01) and consuming SSB (P trend<0·01) and energy drinks (P trend<0·01) in a dose-response manner with adjustments for age, sex, ethnicity, socio-economic status, tobacco, alcohol and cannabis use as well as BMI. However, there was no evidence of a significant association between use of SNS and BMI before or after adjusting for all the covariates and unhealthy eating behaviours. In conclusion, our results suggest associations between the use of SNS and unhealthy eating behaviours among youth. Given the popularity of SNS, more efforts are needed to better understand the impact of social networks on eating behaviours and risk of excess weight.

Defining a mismatch: differences in usage of social networking sites between medical students and the faculty who teach them.

PubMed

Brisson, Gregory E; Fisher, Matthew J; LaBelle, Mark W; Kozmic, Sarah E

2015-01-01

Use of social networking sites (SNS) by medical students is increasing, and some students lack awareness of pitfalls arising from the intersection of social networking and medicine. Many institutions have developed guidelines on using SNS, but they are insufficient for students. Educators need new methods to train students on the appropriate use of this technology, but more information is needed before implementing change. Differences in SNS usage between students and faculty were examined. The goal was to evaluate four content areas: SNS usage patterns, attitudes regarding activity on SNS, experience with patient interactions online, and awareness of institutional guidelines on use of SNS. A cross-sectional survey took place at Feinberg School of Medicine, Northwestern University, in 2012. Participants included all students and a cohort of faculty who teach them in a class on professionalism. The response rate was 42% by students (300/711) and 78% by faculty (31/40). Of the students, 94% use SNS, compared to 48% of faculty. Students were more likely than faculty to display content they would not want patients to see (57% vs. 27%), report seeing inappropriate content on colleagues' SNS profiles (64% vs. 42%), and ignore harmful postings by colleagues (25% vs. 7%). Faculty were more likely than students to have been approached by patients on SNS (53% vs. 3%). Most participants were unlikely to conduct Internet searches on patients. Students are more likely than faculty to use SNS and use it very differently than faculty. Students would benefit from training on appropriate use of SNS. Topics that should be addressed include editing one's online presence, managing friend requests from patients, dealing with colleagues who post harmful content, conducting Internet searches on patients, and discussion of boundaries to identify potential harms associated with SNS usage. Differences in usage between students and faculty raise questions if faculty are well suited to provide this training.

The Effect of Loneliness on Social Networking Sites Use and Its Related Behaviors.

PubMed

Ranaeiy, Samira; Taghavi, Mohammad Reza; Goodarzi, Mohammad Ali

2016-08-01

The current research was conducted to examine the effect of "Loneliness", on time spent in Social Networking Sites (S.N.S), main reasons for S.N.S use, and its related behaviors. 156 students of Shiraz University voluntarily participated in this research. Loneliness was assessed usingthe UCLA Loneliness scale. 25% of highest scoring students reported that they were lonely whereas 25% of the lowest scoring students were considered to be non-lonely. The positive and negative reasons of using S.N.S were assessed based on Reasons for Internet Use Scale, and internet behaviors were assessed based on Scale of Internet Behaviors. There was no difference in time spent in S.N.S as well as the positive and negative reasons of using S.N.S (contrary to literature), but internet behaviors showed a significant difference between "lonely" and "non-lonely" individuals. "Lonely" and "non-lonely" individuals showed a significant difference in "social aspect" of S.N.S behaviors. There was also a significant difference between "Lonely" and "non-Lonely" individuals in "Negative impact" of S.N.S behaviors. Yet, there seemed to be no difference in "competency and convenience aspect" of S.N.S behaviors. This study suggested that there is no difference between lonely and non-lonely individuals in reasons for using S.N.S and time spent in S.N.S. This finding stands contrary to previous research findings and general literature on the subject In other words, what drives people to S.N.S at the first place shows no significant difference between lonely and non-lonely individuals while after attending S.N.S, social behavior of lonely individuals shows a significant difference which is consistently enhanced online. Lonely people also significantly develop internet-related problems in their daily functioning, including interference with real life socializing.

[Influence of collagen/fibroin scaffolds containing silver nanoparticles on dermal regeneration of full-thickness skin defect wound in rat].

PubMed

You, Z G; Zhang, L P; Wang, X G; Zhou, H L; Guo, S X; Wu, P; Han, C M

2017-02-20

Objective: To explore the influence of collagen/fibroin scaffolds containing silver nanoparticles on dermal regeneration of full-thickness skin defect wound in rat. Methods: Eighty-one collagen/fibroin scaffolds containing silver nanoparticles (with the mass concentration of silver nanoparticles as 10 mg/L) and 81 collagen/fibroin scaffolds without silver nanoparticles were produced respectively with freeze-drying method and enrolled as silver nanoparticles scaffold group (SNS) and control scaffold group (CS). Nine scaffolds in each group were cultured with human fibroblasts. At post culture hour (PCH) 2, 12, and 24, the human fibroblasts adherent to the scaffolds ( n =3) in two groups were counted. Four full-thickness skin defect wounds were reproduced on the back of each one of the 36 SD rats. The rats were divided into groups SNS (wounds were transplanted with collagen/fibroin scaffolds containing silver nanoparticles) and CS (wounds were transplanted with collagen/fibroin scaffolds without silver nanoparticles) according to the random number table, with 18 rats in each group. In post surgery week (PSW) 1, 2, and 4, 6 rats in each group were sacrificed respectively for general observation, observation of histological structure, inflammatory cell infiltration, and collagen deposition with HE staining, count of CD68 positive cells with immunohistochemical staining, and mRNA expressions of interleukin-6 (IL-6) and IL-10 with real-time fluorescent quantitative reverse transcription polymerase chain reaction. Data were processed with analysis of variance of factorial design, t test, and Bonferroni correction. Results: (1) At PCH 2, 12, and 24, the numbers of human fibroblasts adherent to the scaffolds in the two groups were close (with t values from 1.77 to 2.60, P values above 0.05). (2) In PSW 1, no obvious symptom of infection was observed in wound or wound edge of rats in group SNS with obvious vascularization of scaffolds, while obvious symptoms of infection were observed in wounds of rats in group CS with some scaffolds exfoliated. In PSW 2, the scaffolds were firmly attached to the wounds of rats in group SNS, while obvious contracture was observed in the wounds of rats in group CS with a lot of scaffolds exfoliated. In PSW 4, the scaffolds covered the wounds of rats in group SNS with obvious epithelization on the surface of the scaffolds, while all the scaffolds exfoliated, leaving obvious contracture of residual wounds of rats in group CS. (3) In PSW 1 and 2, compared with those in group CS, more collagen secretion and tissue regeneration and less inflammatory cell infiltration in the scaffolds were observed in the wounds of rats in group SNS. In PSW 4, obvious epithelization was observed in the wounds of rats in group SNS, while inflammatory cell infiltration was observed without obvious epithelization in the wounds of rats in group CS. (4) In PSW 1, the number of CD68 positive cells in the wounds of rats in group SNS [(54±10) /mm(2)] was similar to that in group CS [(78±7) /mm(2,) t =1.52, P >0.05]. In PSW 2 and 4, the numbers of CD68 positive cells in the wounds of rats in group SNS [(154±10) and (77±7) /mm(2)] were significantly less than those in group CS [(268±16) and (136±13) /mm(2,) with t values respectively 7.31 and 3.83, P values below 0.01] respectively. (5) Except for the expression in PSW 4 ( t =1.23, P >0.05), the mRNA expressions of IL-6 in the wounds of rats in group SNS in PSW 1 and 2 were significantly lower than those in group CS (with t values respectively 13.12 and 4.65, P values below 0.01). Except for the expression in PSW 1 ( t =3.08, P <0.05), the mRNA expressions of IL-10 in PSW 2 and 4 in the wounds of rats in the two groups were similar (with t values respectively 2.14 and 0.49, P values above 0.05). Conclusions: Besides good biocompatibility, collagen/fibroin scaffolds containing silver nanoparticles have obvious effect in modulating inflammation, thus they can accelerate dermal regeneration induced by collagen/fibroin scaffolds for wound repair.

Ultrathin SnO2 nanorods: template- and surfactant-free solution phase synthesis, growth mechanism, optical, gas-sensing, and surface adsorption properties.

PubMed

Xi, Guangcheng; Ye, Jinhua

2010-03-01

A novel template- and surfactant-free low temperature solution-phase method has been successfully developed for the controlled synthesis of ultrathin SnO(2) single-crystalline nanorods for the first time. The ultrathin SnO(2) single-crystalline nanorods are 2.0 +/- 0.5 nm in diameter, which is smaller than its exciton Bohr radius. The ultrathin SnO(2) nanorods show a high specific area (191.5 m(2) g(-1)). Such a thin SnO(2) single-crystalline nanorod is new in the family of SnO(2) nanostrucures and presents a strong quantum confinement effect. Its formation depends on the reaction temperature as well as on the concentration of the urea solution. A nonclassical crystallization process, Ostwald ripening process followed by an oriented attachment mechanism, is proposed based on the detailed observations from a time-dependent crystal evolution process. Importantly, such structured SnO(2) has shown a strong structure-induced enhancement of gas-sensing properties and has exhibited greatly enhanced gas-sensing property for the detection of ethanol than that of other structured SnO(2), such as the powders of nanobelts and microrods. Moreover, these ultrathin SnO(2) nanorods exhibit excellent ability to remove organic pollutant in wastewater by enormous surface adsorption. These properties are mainly attributed to its higher surface-to-volume ratio and ultrathin diameter. This work provides a novel low temperature, green, and inexpensive pathway to the synthesis of ultrathin nanorods, offering a new material form for sensors, solar cells, catalysts, water treatments, and other applications.

Optimization of Neuromodulation for Bladder Control in a Rat Cystitis Model.

PubMed

Su, Xin; Nickles, Angela; Nelson, Dwight E

2016-01-01

In a bladder overactivity model of cystitis induced by intravesical infusion of acetic acid (a.a.), several parameters of spinal nerve stimulation (SNS) were optimized using continuous infusion cystometry. The optimal stimulation was further characterized through measurements of urodynamic function using single-fill cystometry. In anesthetized male rats, a cannula was placed into the bladder dome for saline or 0.3% a.a. infusion and intravesical pressure monitoring. For SNS, two teflon-coated stainless steel electrodes were placed bilaterally under each of the L6 spinal nerves, and current stimulation was controlled independently using two Grass stimulators. Stimulation of 1 Hz or 50 Hz at motor threshold (Tmot ) was ineffective for altering bladder activities, but 10-Hz SNS increased the infused volume (IV) in a stimulation intensity-dependent fashion (P < 0.01, mixed model repeated analysis). Pairwise comparisons of IV differences to each stimulation intensity show that IV during 1 × Tmot stimulation was significantly larger than 0 × Tmot (no stim, P = 0.001), while the IV during 2 × Tmot stimulation was significantly larger than other intensities tested (P < 0.01). The mean IV (±SEM) during 0 × Tmot (no stim), 0.5 × Tmot , 1 × Tmot , and 2 × Tmot were 0.23 ± 0.04 mL, 0.25 ± 0.03 mL, 0.26 ± 0.03 mL, and 0.40 ± 0.04 mL, respectively. In single-fill cystometry, 10-Hz SNS at 1 × Tmot and 2 × Tmot stimulation increased the IV, or voiding duration and threshold pressure. SNS did not produce significant effects on basal pressure and micturition pressure. SNS significantly attenuates hypersensitive micturition reflex; 10 Hz and high-intensity stimulation are mostly effective. Acute peripheral nerve activation increases the functional bladder capacity, which may be via mechanisms on the afferent arm of the bladder micturition reflex. © 2015 International Neuromodulation Society.

Electrochemical Corrosion Properties of Commercial Ultra-Thin Copper Foils

NASA Astrophysics Data System (ADS)

Yen, Ming-Hsuan; Liu, Jen-Hsiang; Song, Jenn-Ming; Lin, Shih-Ching

2017-08-01

Ultra-thin electrodeposited Cu foils have been developed for substrate thinning for mobile devices. Considering the corrosion by residual etchants from the lithography process for high-density circuit wiring, this study investigates the microstructural features of ultra-thin electrodeposited Cu foils with a thickness of 3 μm and their electrochemical corrosion performance in CuCl2-based etching solution. X-ray diffraction and electron backscatter diffraction analyses verify that ultra-thin Cu foils exhibit a random texture and equi-axed grains. Polarization curves show that ultra-thin foils exhibit a higher corrosion potential and a lower corrosion current density compared with conventional (220)-oriented foils with fan-like distributed fine-elongated columnar grains. Chronoamperometric results also suggest that ultra-thin foils possess superior corrosion resistance. The passive layer, mainly composed of CuCl and Cu2O, forms and dissolves in sequence during polarization.

Metal Immiscibility Route to Synthesis of Ultrathin Carbides, Borides, and Nitrides.

PubMed

Wang, Zixing; Kochat, Vidya; Pandey, Prafull; Kashyap, Sanjay; Chattopadhyay, Soham; Samanta, Atanu; Sarkar, Suman; Manimunda, Praveena; Zhang, Xiang; Asif, Syed; Singh, Abhisek K; Chattopadhyay, Kamanio; Tiwary, Chandra Sekhar; Ajayan, Pulickel M

2017-08-01

Ultrathin ceramic coatings are of high interest as protective coatings from aviation to biomedical applications. Here, a generic approach of making scalable ultrathin transition metal-carbide/boride/nitride using immiscibility of two metals is demonstrated. Ultrathin tantalum carbide, nitride, and boride are grown using chemical vapor deposition by heating a tantalum-copper bilayer with corresponding precursor (C 2 H 2 , B powder, and NH 3 ). The ultrathin crystals are found on the copper surface (opposite of the metal-metal junction). A detailed microscopy analysis followed by density functional theory based calculation demonstrates the migration mechanism, where Ta atoms prefer to stay in clusters in the Cu matrix. These ultrathin materials have good interface attachment with Cu, improving the scratch resistance and oxidation resistance of Cu. This metal-metal immiscibility system can be extended to other metals to synthesize metal carbide, boride, and nitride coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface functionalized Cu2Zn1- x Cd x SnS4 quinternary alloyed nanostructure for DNA sensing

NASA Astrophysics Data System (ADS)

Ibraheam, A. S.; Al-Douri, Y.; Voon, C. H.; Foo, K. L.; Azizah, N.; Gopinath, S. C. B.; Ameri, M.; Ibrahim, Sattar S.

2017-03-01

A sensing plate of extended Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures, fabricated on an oxidized silicon substrate by the sol-gel method, is reported in this paper. The fabricated device was characterized and analyzed via field emission-scanning electron microscopy, X-ray diffraction (XRD), and photoluminescence (PL). The XRD peaks shifted towards the lower angle side alongside increasing concentration of cadmium. The average diameter of the Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures falls between 21.55 and 43.12 nm, while the shift of the PL bandgap was from 1.81 eV ( x = 0) to 1.72 eV ( x = 1). The resulting Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures components were functionalized with oligonucleotides probe DNA molecules and interacted with the target, exhibiting good sensing capabilities due to its large surface-to-volume ratio. The fabrication, immobilization, and hybridization processes were analyzed via representative current-voltage ( I- V) plots. Its electrical profile shows that the device is capable to distinguish biomolecules. Its high performance was evident from the linear relationship between the probe DNA from cervical cancer and the target DNA, showing its applicability for medical applications.

Self-Formed Channel Devices Based on Vertically Grown 2D Materials with Large-Surface-Area and Their Potential for Chemical Sensor Applications.

PubMed

Kim, Chaeeun; Park, Jun-Cheol; Choi, Sun Young; Kim, Yonghun; Seo, Seung-Young; Park, Tae-Eon; Kwon, Se-Hun; Cho, Byungjin; Ahn, Ji-Hoon

2018-04-01

2D layered materials with sensitive surfaces are promising materials for use in chemical sensing devices, owing to their extremely large surface-to-volume ratios. However, most chemical sensors based on 2D materials are used in the form of laterally defined active channels, in which the active area is limited to the actual device dimensions. Therefore, a novel approach for fabricating self-formed active-channel devices is proposed based on 2D semiconductor materials with very large surface areas, and their potential gas sensing ability is examined. First, the vertical growth phenomenon of SnS 2 nanocrystals is investigated with large surface area via metal-assisted growth using prepatterned metal electrodes, and then self-formed active-channel devices are suggested without additional pattering through the selective synthesis of SnS 2 nanosheets on prepatterned metal electrodes. The self-formed active-channel device exhibits extremely high response values (>2000% at 10 ppm) for NO 2 along with excellent NO 2 selectivity. Moreover, the NO 2 gas response of the gas sensing device with vertically self-formed SnS 2 nanosheets is more than two orders of magnitude higher than that of a similar exfoliated SnS 2 -based device. These results indicate that the facile device fabrication method would be applicable to various systems in which surface area plays an important role. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atomistic Description of Thiostannate-Capped CdSe Nanocrystals: Retention of Four-Coordinate SnS4 Motif and Preservation of Cd-Rich Stoichiometry

PubMed Central

2016-01-01

Colloidal semiconductor nanocrystals (NCs) are widely studied as building blocks for novel solid-state materials. Inorganic surface functionalization, used to displace native organic capping ligands from NC surfaces, has been a major enabler of electronic solid-state devices based on colloidal NCs. At the same time, very little is known about the atomistic details of the organic-to-inorganic ligand exchange and binding motifs at the NC surface, severely limiting further progress in designing all-inorganic NCs and NC solids. Taking thiostannates (K4SnS4, K4Sn2S6, K6Sn2S7) as typical examples of chalcogenidometallate ligands and oleate-capped CdSe NCs as a model NC system, in this study we address these questions through the combined application of solution 1H NMR spectroscopy, solution and solid-state 119Sn NMR spectroscopy, far-infrared and X-ray absorption spectroscopies, elemental analysis, and by DFT modeling. We show that through the X-type oleate-to-thiostannate ligand exchange, CdSe NCs retain their Cd-rich stoichiometry, with a stoichiometric CdSe core and surface Cd adatoms serving as binding sites for terminal S atoms of the thiostannates ligands, leading to all-inorganic (CdSe)core[Cdm(Sn2S7)yK(6y-2m)]shell (taking Sn2S76– ligand as an example). Thiostannates SnS44– and Sn2S76– retain (distorted) tetrahedral SnS4 geometry upon binding to NC surface. At the same time, experiments and simulations point to lower stability of Sn2S64– (and SnS32–) in most solvents and its lower adaptability to the NC surface caused by rigid Sn2S2 rings. PMID:25597625

[Color selection of ultrathin veneers in clinic].

PubMed

Feng, Sun

2016-12-01

Ultrathin veneer is a new therapeutic technology developed from minimally invasive theories. Ultrathin veneer alters the unwanted shape and color of a tooth through minimal or lack of preparation. The color of tooth after restoration is mixed with the natural color of tooth, the original color of veneer, and the color of bonding material because of ultrathin (approximately 0.2 mm) veneer. Thus, the color is affected by numerous variations. Full considerations are required for creating designs. The author summarizes clinical points and provides suggestions for ultrathin veneer in color.

Ultrathin Nickel Hydroxide and Oxide Nanosheets: Synthesis, Characterizations and Excellent Supercapacitor Performances

PubMed Central

Zhu, Youqi; Cao, Chuanbao; Tao, Shi; Chu, Wangsheng; Wu, Ziyu; Li, Yadong

2014-01-01

High-quality ultrathin two-dimensional nanosheets of α-Ni(OH)2 are synthesized at large scale via microwave-assisted liquid-phase growth under low-temperature atmospheric conditions. After heat treatment, non-layered NiO nanosheets are obtained while maintaining their original frame structure. The well-defined and freestanding nanosheets exhibit a micron-sized planar area and ultrathin thickness (<2 nm), suggesting an ultrahigh surface atom ratio with unique surface and electronic structure. The ultrathin 2D nanostructure can make most atoms exposed outside with high activity thus facilitate the surface-dependent electrochemical reaction processes. The ultrathin α-Ni(OH)2 and NiO nanosheets exhibit enhanced supercapacitor performances. Particularly, the α-Ni(OH)2 nanosheets exhibit a maximum specific capacitance of 4172.5 F g−1 at a current density of 1 A g−1. Even at higher rate of 16 A g−1, the specific capacitance is still maintained at 2680 F g−1 with 98.5% retention after 2000 cycles. Even more important, we develop a facile and scalable method to produce high-quality ultrathin transition metal hydroxide and oxide nanosheets and make a possibility in commercial applications. PMID:25168127

The use of social networking sites: A risk factor for using alcohol, marijuana, and synthetic cannabinoids?

PubMed

Gutierrez, Kevin M; Cooper, Theodore V

2016-06-01

The use of social networking sites (SNS) has become a central aspect of youth culture allowing individuals to explore and assert their identities. A commonly portrayed online identity is an "alcohol identity," and past research suggests such identities may contribute to one's risk of using alcohol. The present study builds on past research by examining the relationship between alcohol, marijuana, and synthetic cannabinoid use (e.g., Spice, K2) and time spent on SNS in a sample of college students. Six hundred ninety nine undergraduates (62.4% female; Mage=21.0, SD=8.56) were recruited from a university on the U.S./Mexico border for an online study. Participants completed measures assessing demographics, substance use history, and amount of time spent on SNS. Participants reported spending 46h per month on SNS. Seventy-one percent, 14%, and 3% of the sample reported past month use of alcohol, marijuana, and synthetic cannabinoids, respectively. Regression analyses revealed that hours spent on SNS in the past month were significantly associated with frequency of alcohol (p<0.001) and synthetic cannabinoid use (p<0.001). In addition, being male was associated with frequency of alcohol and marijuana use in the past month (p<0.001 and p<0.001, respectively). These findings suggest that assessment of time spent on SNS is warranted in studies investigating drug use among college students. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Lessons learned from use of social network strategy in HIV testing programs targeting African American men who have sex with men.

PubMed

McCree, Donna H; Millett, Gregorio; Baytop, Chanza; Royal, Scott; Ellen, Jonathan; Halkitis, Perry N; Kupprat, Sandra A; Gillen, Sara

2013-10-01

We report lessons derived from implementation of the Social Network Strategy (SNS) into existing HIV counseling, testing, and referral services targeting 18- to 64-year-old Black gay, bisexual, and other men who have sex with men (MSM). The SNS procedures used in this study were adapted from a Centers for Disease Control and Prevention-funded, 2-year demonstration project involving 9 community-based organizations (CBOs) in 7 cities. Under the SNS, HIV-positive and HIV-negative men at high risk for HIV (recruiters) were enlisted to identify and recruit persons from their social, sexual, or drug-using networks (network associates) for HIV testing. Sites maintained records of modified study protocols for ascertaining lessons learned. The study was conducted between April 2008 and May 2010 at CBOs in Washington, DC, and New York, New York, and at a health department in Baltimore, Maryland. Several common lessons regarding development of the plan, staffing, training, and use of incentives were identified across the sites. Collectively, these lessons indicate use of SNS is resource-intensive, requiring a detailed plan, dedicated staff, and continual input from clients and staff for successful implementation. SNS may provide a strategy for identifying and targeting clusters of high-risk Black MSM for HIV testing. Given the resources needed to implement the strategy, additional studies using an experimental design are needed to determine the cost-effectiveness of SNS compared with other testing strategies.

In-situ sulfuration synthesis of sandwiched spherical tin sulfide/sulfur-doped graphene composite with ultra-low sulfur content

NASA Astrophysics Data System (ADS)

Zhao, Bing; Yang, Yaqing; Wang, Zhixuan; Huang, Shoushuang; Wang, Yanyan; Wang, Shanshan; Chen, Zhiwen; Jiang, Yong

2018-02-01

SnS is widely studied as anode materials since of its superior structural stability and physicochemical property comparing with other Sn-based composites. Nevertheless, the inconvenience of phase morphology control and excessive consumption of sulfur sources during synthesis hinder the scalable application of SnS nanocomposites. Herein, we report a facile in-situ sulfuration strategy to synthesize sandwiched spherical SnS/sulfur-doped graphene (SnS/S-SG) composite. An ultra-low sulfur content with approximately stoichiometric ratio of Sn:S can effectively promote the sulfuration reaction of SnO2 to SnS and simultaneous sulfur-doping of graphene. The as-prepared SnS/S-SG composite shows a three-dimensional interconnected spherical structure as a whole, in which SnS nanoparticles are sandwiched between the multilayers of graphene sheets forming a hollow sphere. The sandwiched sphere structure and high S doping amount can improve the binding force between SnS and graphene, as well as the structural stability and electrical conductivity of the composite. Thus, a high reversibility of conversion reaction, promising specific capacity (772 mAh g-1 after 100 cycles at 0.1 C) and excellent rate performance (705 and 411 mAh g-1 at 1 C and 10 C, respectively) are exhibited in the SnS/S-SG electrode, which are much higher than that of the SnS/spherical graphene synthesized by traditional post-sulfuration method.

Problematic internet use and social networking site use among Dutch adolescents.

PubMed

Jelenchick, Lauren A; Hawk, Skyler T; Moreno, Megan A

2016-02-01

Problematic Internet use (PIU), defined as Internet use that is risky, excessive, or impulsive in nature and leads to adverse life consequences, is an emerging health concern among adolescents worldwide. Social networking site (SNS) use is among the most popular and common Internet use activities for youth; however, risks of SNS use for PIU remain unexplored. The purpose of this study was to determine the prevalence of adolescents at risk for PIU within a national school-based sample of Dutch adolescents and to explore associations between SNS use and PIU. Adolescents were recruited from six public schools in the Netherlands to complete a survey, which included SNS use questions and the Problematic and Risky Internet Use Screening Scale (PRIUSS). Logistic regression models were used to test associations between risk for PIU and demographic or SNS use variables. A total of 474 adolescents participated (98% response rate), and 11% (n=51) of adolescents were at risk for PIU. Risk for PIU was significantly associated with gender (p=0.015), increased age (p=0.034), and posting on SNS more than four times a day (p=0.003). Risk for PIU was not associated with number of SNS profiles, SNS preference or the number of online friends. Findings illustrate high risk groups for PIU includes males and older teens. Findings also illuminate that risk for PIU related to SNS was not associated with a specific SNS or number of SNSs used but was related to one's personal investment in SNSs by posting four or more times a day.

Cross Space: The Exploration of SNS-Based Writing Activities in a Multimodal Learning Environment

ERIC Educational Resources Information Center

Lee, Kwang-Soon; Kim, Bong-Gyu

2016-01-01

This study explores the positive learning effect of formulating English sentences via Social Network Service (SNS; "Kakao-Talk") on less proficient L2 university students' (LPSs') writing, when the application is utilized as a tool to link in and out-of class activities in a multimodal-learning environment. Its objective is also to…

Structure and mechanical properties of foils made of nanocrystalline beryllium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhigalina, O. M., E-mail: zhigal@ns.crys.ras.ru; Semenov, A. A.; Zabrodin, A. V.

2016-07-15

The phase composition and structural features of (45–90)-μm-thick foils obtained from nanocrystalline beryllium during multistep thermomechanical treatment have been established using electron microscopy, electron diffraction, electron backscattering diffraction, and energy-dispersive analysis. This treatment is shown to lead to the formation of a structure with micrometer- and submicrometer-sized grains. The minimum average size of beryllium grains is 352 nm. The inclusions of beryllium oxide (BeO) of different modifications with tetragonal (sp. gr. P4{sub 2}/mnm) and hexagonal (sp. gr. P6{sub 3}/mmc) lattices are partly ground during deformation to a size smaller than 100 nm and are located along beryllium grain boundaries inmore » their volume, significantly hindering migration during treatment. The revealed structural features of foils with submicrometer-sized crystallites provide the thermal stability of their structural state. Beryllium with this structure is a promising material for X-ray instrument engineering and for the production of ultrathin (less than 10 μm) vacuum-dense foils with very high physicomechanical characteristics.« less

INCREASED UNDERSTANDING OF BEAM LOSSES FROM THE SNS LINAC PROTON EXPERIMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aleksandrov, Alexander V; Shishlo, Andrei P; Plum, Michael A

Beam loss is a major concern for high power hadron accelerators such as the Spallation Neutron Source (SNS). An unexpected beam loss in the SNS superconducting linac (SCL) was observed during the power ramp up and early operation. Intra-beam-stripping (IBS) loss, in which interactions between H- particles within the accelerated bunch strip the outermost electron, was recently identified as a possible cause of the beam loss. A set of experiments using proton beam acceleration in the SNS linac was conducted, which supports IBS as the primary beam loss mechanism in the SNS SCL.

Optimisation of fluorescence guidance during robot-assisted laparoscopic sentinel node biopsy for prostate cancer.

PubMed

KleinJan, Gijs H; van den Berg, Nynke S; Brouwer, Oscar R; de Jong, Jeroen; Acar, Cenk; Wit, Esther M; Vegt, Erik; van der Noort, Vincent; Valdés Olmos, Renato A; van Leeuwen, Fijs W B; van der Poel, Henk G

2014-12-01

The hybrid tracer was introduced to complement intraoperative radiotracing towards the sentinel nodes (SNs) with fluorescence guidance. Improve in vivo fluorescence-based SN identification for prostate cancer by optimising hybrid tracer preparation, injection technique, and fluorescence imaging hardware. Forty patients with a Briganti nomogram-based risk >10% of lymph node (LN) metastases were included. After intraprostatic tracer injection, SN mapping was performed (lymphoscintigraphy and single-photon emission computed tomography with computed tomography (SPECT-CT)). In groups 1 and 2, SNs were pursued intraoperatively using a laparoscopic gamma probe followed by fluorescence imaging (FI). In group 3, SNs were initially located via FI. Compared with group 1, in groups 2 and 3, a new tracer formulation was introduced that had a reduced total injected volume (2.0 ml vs. 3.2 ml) but increased particle concentration. For groups 1 and 2, the Tricam SLII with D-Light C laparoscopic FI (LFI) system was used. In group 3, the LFI system was upgraded to an Image 1 HUB HD with D-Light P system. Hybrid tracer-based SN biopsy, extended pelvic lymph node dissection, and robot-assisted radical prostatectomy. Number and location of the preoperatively identified SNs, in vivo fluorescence-based SN identification rate, tumour status of SNs and LNs, postoperative complications, and biochemical recurrence (BCR). Mean fluorescence-based SN identification improved from 63.7% (group 1) to 85.2% and 93.5% for groups 2 and 3, respectively (p=0.012). No differences in postoperative complications were found. BCR occurred in three pN0 patients. Stepwise optimisation of the hybrid tracer formulation and the LFI system led to a significant improvement in fluorescence-assisted SN identification. Preoperative SPECT-CT remained essential for guiding intraoperative SN localisation. Intraoperative fluorescence-based SN visualisation can be improved by enhancing the hybrid tracer formulation and laparoscopic fluorescence imaging system. Copyright © 2014 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Social Networking Site Use While Driving: ADHD and the Mediating Roles of Stress, Self-Esteem and Craving

PubMed Central

Turel, Ofir; Bechara, Antoine

2016-01-01

Background: Adults who present ADHD symptoms have an increased risk for vehicle accidents. One conceivable overlooked account for this association is the possibility that people with ADHD symptoms use rewarding technologies such as social networking sites (SNS) while driving, more than others. The objective of this study was to understand if and how ADHD symptoms can promote SNS use while driving and specifically to conceptualize and examine mechanisms which may underlie this association. To do so, ADHD is viewed in this study as an underlying syndrome that promotes SNS use while driving in a manner similar to how addictive syndromes promote compulsive seeking of drug rewards. Methods: Time-lagged survey data regarding ADHD, stress, self-esteem, SNS craving experience, SNS use while driving, and control variables were collected from a sample of 457 participants who use a popular SNS (Facebook) and drive, after face-validity examination with a panel of five users and pretest with a sample of 47. These data were subjected to structural equation modeling (SEM) analyses using the frequency of ADHD symptoms measured with ASRS v1.1 Part A as a continuous variable, as well as multivariate analysis of variance using ADHD classification based on ASRS v1.1 scoring guidelines. Results: ADHD symptoms promoted increased stress and reduced self-esteem, which in turn, together with ADHD symptoms, increased one's cravings to use the SNS. These cravings ultimately translated into increased SNS use while driving. Using the ASRS v1.1 classification, people having symptoms highly consistent with ADHD presented elevated levels of stress, cravings to use the SNS, and SNS use while driving, as well as decreased levels of self-esteem. Cravings to use the SNS among men were more potent than among women. Conclusion: SNS use while driving may be more prevalent than previously assumed and may be indirectly associated with ADHD symptoms. It is a new form of impulsive and risky behavior which is more common among people with symptoms compatible with ADHD than among others. Consistent with addiction and decision making models, SNS use while driving can be viewed as a form of a compensatory reward seeking behavior. As such, prevention and reduction interventions that target the mediating perceptions and states should be devised. PMID:27065923

Social Networking Site Use While Driving: ADHD and the Mediating Roles of Stress, Self-Esteem and Craving.

PubMed

Turel, Ofir; Bechara, Antoine

2016-01-01

Adults who present ADHD symptoms have an increased risk for vehicle accidents. One conceivable overlooked account for this association is the possibility that people with ADHD symptoms use rewarding technologies such as social networking sites (SNS) while driving, more than others. The objective of this study was to understand if and how ADHD symptoms can promote SNS use while driving and specifically to conceptualize and examine mechanisms which may underlie this association. To do so, ADHD is viewed in this study as an underlying syndrome that promotes SNS use while driving in a manner similar to how addictive syndromes promote compulsive seeking of drug rewards. Time-lagged survey data regarding ADHD, stress, self-esteem, SNS craving experience, SNS use while driving, and control variables were collected from a sample of 457 participants who use a popular SNS (Facebook) and drive, after face-validity examination with a panel of five users and pretest with a sample of 47. These data were subjected to structural equation modeling (SEM) analyses using the frequency of ADHD symptoms measured with ASRS v1.1 Part A as a continuous variable, as well as multivariate analysis of variance using ADHD classification based on ASRS v1.1 scoring guidelines. ADHD symptoms promoted increased stress and reduced self-esteem, which in turn, together with ADHD symptoms, increased one's cravings to use the SNS. These cravings ultimately translated into increased SNS use while driving. Using the ASRS v1.1 classification, people having symptoms highly consistent with ADHD presented elevated levels of stress, cravings to use the SNS, and SNS use while driving, as well as decreased levels of self-esteem. Cravings to use the SNS among men were more potent than among women. SNS use while driving may be more prevalent than previously assumed and may be indirectly associated with ADHD symptoms. It is a new form of impulsive and risky behavior which is more common among people with symptoms compatible with ADHD than among others. Consistent with addiction and decision making models, SNS use while driving can be viewed as a form of a compensatory reward seeking behavior. As such, prevention and reduction interventions that target the mediating perceptions and states should be devised.

Effect of annealing on physical characteristics of the vacuum evaporated mixed phase Sn x S y thin films

NASA Astrophysics Data System (ADS)

Banotra, A.; Padha, N.

2017-11-01

The mixed phase Sn x S y films of the thickness of 200 nm were obtained by annealing in an indigenously designed furnace at 473 K, 523 K, 573 K and 623 K for 1 h at each temperature. Prior to annealing, the precursor ‘Sn’ and ‘S’ materials were mixed up in a ball milling setup and thermally evaporated at the vacuum pressure ~2  ×  10-6 mbar on corning glass substrate. The increase in the annealing temperature influenced the reaction kinetics of ‘Sn’ and ‘S’ materials and led to the formation of SnS phase at 473 K. The SnS phase existed from 473 K to 573 K and transformed to Sn2S3 at temperatures between 573 K and 623 K. Besides this, the SnS2 phase co-existed in all undertaken temperatures where intensity of its most prominent peak increased with increase in annealing temperature. The transmittance (%) values of the undertaken films increased with increase in the annealing temperature in the wavelengths varying from 400 nm (visible) to 1600 nm (NIR). The absorption coefficient (α) values decreased with increase in annealing temperature from 1  ×  105 to 4  ×  104 cm-1 in the visible region and attained saturation values (~2  ×  104 cm-1) in the NIR region. The films possessed direct bandgap (E g) with values increasing from 1.90 eV to 2.82 eV with increase in the annealing temperature from 473 K to 623 K it also possessed indirect bandgaps with E g values varying from 0.82 eV to 1.52 eV with increase in annealing temperature in the same temperature range. The 473 K annealed samples provided irregular shaped SnS grains indicated by bright crystallites which reached to their stable position with enhanced crystallinity at the annealing temperatures of 523 K and 573 K. The SnS grains, however, reduced to lesser number at 623 K due to growth of Sn2S3 crystallites at the expense of SnS. The ‘S’ rich SnS phase (SnS2) crystallites were seen represented by darker crystallites appeared at 523 K, 573 K and 623 K. The current-voltage (I-V) study of the FTO/Film/Ag structure confirmed the schottky diode formation between Ag and film interface. There are variations in the I-V behaviour of diodes which resulted in random changes in the values of ‘ideality factor’ and ‘barrier heights’. The changes in diode parameters may be due to variation in the interface states, surface defects and barrier inhomogenities occurring due to compositional changes in Sn x S y films.

SNS Extraction Fast Kicker System Development

DTIC Science & Technology

2003-06-01

SNS EXTRACTION FAST KICKER SYSTEM DEVELOPMENT * W. Zhang ξ, J. Sandberg, R. Lambiase, Y.Y. Lee, R. Lockey, J. Mi, T. Nehring, C. Pai, N. Tsoupas...Oak Ridge, TN 37831 * SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for...the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and

Pharmacists' perceptions of professionalism on social networking sites.

PubMed

Benetoli, Arcelio; Chen, Timothy F; Schaefer, Marion; Chaar, Betty; Aslani, Parisa

Social networking sites (SNS) are a new venue for communication, and health care professionals, like the general population, are using them extensively. However, their behavior on SNS may influence public perceptions about their professionalism. This study explored how pharmacists separate professional and personal information and activities on SNS, their perceptions of professional behavior on SNS, and opinions on guidelines in this area. In-depth, semi-structured interviews were conducted with international practising pharmacists (n = 31) recruited from a range of countries (n = 9). Initially, pharmacists known to the research team were invited, and thereafter, participants were recruited using a snowballing technique. The interviews lasted from 30 to 120 min. All interviews were recorded, transcribed verbatim, and thematically analyzed. A majority of participants mixed professional and personal information and activities on SNS, and about one third adopted a separation strategy where professional information and activities were clearly separated from personal ones (e.g. two different SNS accounts, or one particular SNS for professional use and another platform for personal purposes). Most participants expressed concern over how pharmacists present themselves and behave in SNS when they reported (un)professional behaviors of peers they had observed. Examples of perceived unprofessional behaviors included revealing details of personal life and activities; open complaints about the pharmacy sector, co-workers, physicians, and patients; inappropriate description of pharmacists' roles and activities; and breaches of patient confidentiality. Positive professional behaviors, such as expression of compassion for patients, examples of effective patient management, promotion of pharmacists' role, and correction of misleading health information being spread online were also observed. There was no consensus on having professional social media guidelines. Some preferred SNS to be unregulated while most believed certain guidance was needed to maintain high professional standards in the online environment. A definitive strategy to separate professional and personal information and activities on SNS was not adopted by most pharmacists. E-professionalism issues could negatively impact on the standing of individual practitioners and the profession. Most agreed that education about SNS use would be beneficial; however, support for guidelines or regulations for pharmacists' use of SNS was not unanimous. Copyright © 2016 Elsevier Inc. All rights reserved.

The cost-effectiveness of sacral nerve stimulation (SNS) for the treatment of idiopathic medically refractory overactive bladder (wet) in the UK.

PubMed

Autiero, Silke Walleser; Hallas, Natalie; Betts, Christopher D; Ockrim, Jeremy L

2015-12-01

To estimate the long-term cost-effectiveness of specialised treatment options for medically refractory idiopathic overactive bladder (OAB) wet. The cost-effectiveness of competing treatment options for patients with medically refractory idiopathic OAB wet was estimated from the perspective of the National Health Service in the UK. We compared sacral nerve stimulation (SNS) with percutaneous nerve evaluation (PNE) or tined-lead evaluation (TLE) with optimal medical therapy (OMT), botulinum toxin type A (BoNT-A) injections, and percutaneous tibial nerve stimulation (PTNS). We used a Markov model with a 10-year time horizon for all treatment options with the exception of PTNS, which has a time horizon of 5 years. Costs and effects (measured as quality-adjusted life years) were calculated to derive incremental cost-effectiveness ratios (ICERs). Direct medical resources included are: device and drug acquisition costs, pre-procedure and procedure costs, and the cost of managing adverse events. Deterministic sensitivity analyses were performed to test robustness of results. At 5 years, SNS (PNE or TLE) was more effective and less costly than PTNS. Compared with OMT at 10 years, SNS (PNE or TLE) was more costly and more effective, and compared with BoNT-A, SNS PNE was less costly and more effective, and SNS TLE was more costly and more effective. Decreasing the BoNT-A dose from 150 to 100 IU marginally increased the 10 year ICERs for SNS TLE and PNE (SNS PNE was no longer dominant). However, both SNS options remained cost-effective. In the management of patients with idiopathic OAB wet, the results of this cost-utility analysis favours SNS (PNE or TLE) over PTNS or OMT, and the most efficient treatment strategy is SNS PNE over BoNT-A over a 10-year period. © 2015 The Authors BJU International © 2015 BJU International Published by John Wiley & Sons Ltd.

Exploratory development and services for preparing and examining ultrathin polished sections of lunar rocks and particulates, part 1

NASA Technical Reports Server (NTRS)

Beauchamp, R. H.; Williford, J. F.; Gafford, E. L.

1972-01-01

Development of improved procedures is reported for three classes of lunar materials: dense rocks, breccias, and particulates. High quality ultrathin sections of these materials are obtained. Lists of equipment and supplies, procedures, photomicrographic documentation, and training are provided. Advantages of ultrathin polished sections for conventional and unconventional optical microscopy methods are described. Recommendations are provided for use of ultrathin sections in lunar rock studies, for further refinement of ultrathinning procedures, and for additional training efforts to establish a capability at the Manned Space Center. For Part 2, See N72-50754.

Fabrication and Characterization of Ultrathin-ring Electrodes for Pseudo-steady-state Amperometric Detection.

PubMed

Kitazumi, Yuki; Hamamoto, Katsumi; Noda, Tatsuo; Shirai, Osamu; Kano, Kenji

2015-01-01

The fabrication of ultrathin-ring electrodes with a diameter of 2 mm and a thickness of 100 nm is established. The ultrathin-ring electrodes provide a large density of pseudo-steady-state currents, and realize pseudo-steady-state amperometry under quiescent conditions without a Faraday cage. Under the limiting current conditions, the current response at the ultrathin-ring electrode can be well explained by the theory of the microband electrode response. Cyclic voltammograms at the ultrathin-ring electrode show sigmoidal characteristics with some hysteresis. Numerical simulation reveals that the hysteresis can be ascribed to the time-dependence of pseudo-steady-state current. The performance of amperometry with the ultrathin-ring electrode has been verified in its application to redox enzyme kinetic measurements.

Influence of surface plasmon resonance of Sn nanoparticles and nanosheets on the photoluminescence and Raman spectra of SnS quantum dots

NASA Astrophysics Data System (ADS)

Warrier, Anita R.; Gandhimathi, R.

2018-04-01

We report on enhancement of photoluminescence of SnS quantum dots by embedding them in a mesh of Sn nanostructures. SnS quantum dots with band gap ˜2.7 eV are embedded in a mesh of Sn nanostructures, that are synthesized from tin chloride solution using sodium borohydride as reducing agent. The synthesized Sn nanostructures have a morphology dependent, tunable surface plasmon resonance ranging from UV region (295 nm) to visible region (400 nm) of the electromagnetic spectrum. In the SnS-Sn nanohybrids, the excitons are strongly coupled with plasmons leading to a shift in the excitonic binding energy (˜ 400 meV). Due to the influence of Sn nanoparticles on the SnS quantum dots, the photoluminescence and Raman line intensity is enhanced by an order of ˜103 The enhancement is more pronounced for Sn nanosheets due to the large surface area and visible light surface plasmon resonance.

Patterns of Sympathetic Responses Induced by Different Stress Tasks

PubMed Central

Fechir, M; Schlereth, T; Purat, T; Kritzmann, S; Geber, C; Eberle, T; Gamer, M; Birklein, F

2008-01-01

Stress tasks are used to induce sympathetic nervous system (SNS) arousal. However, the efficacy and the patterns of SNS activation have not been systematically compared between different tasks. Therefore, we analyzed SNS activation during the following stress tasks: Presentation of negative, positive, and – as a control – neutral affective pictures, Color-Word interference test (CWT), mental arithmetic under time limit, singing a song aloud, and giving a spontaneous talk. We examined 11 healthy subjects and recorded the following SNS parameters: Activation of emotional sweating by quantitative sudometry, skin vasoconstriction by laser-Doppler flowmetry, heart rate by ECG, blood pressure by determination of pulse wave transit time (PWTT), and electromyographic (EMG) activity of the trapezius muscle. Moreover, subjective stress ratings were acquired for each task using a visual analog scale. All tasks were felt significantly stressful when compared to viewing neutral pictures. However, SNS activation was not reliable: Affective pictures did not induce a significant SNS response; singing, giving a talk and mental arithmetic selectively increased heart rate and emotional sweating. Only the CWT globally activated the SNS. Regarding all tasks, induction of emotional sweating, increase of heart rate and blood pressure significantly correlated with subjective stress ratings, in contrast to EMG and skin vasoconstriction. Our results show that the activation of the SNS widely varies depending on the stress task. Different stress tasks differently activate the SNS, which is an important finding when considering sympathetic reactions - in clinical situations and in research. PMID:19018304

Design Analysis of SNS Target StationBiological Shielding Monoligh with Proton Power Uprate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bekar, Kursat B.; Ibrahim, Ahmad M.

2017-05-01

This report documents the analysis of the dose rate in the experiment area outside the Spallation Neutron Source (SNS) target station shielding monolith with proton beam energy of 1.3 GeV. The analysis implemented a coupled three dimensional (3D)/two dimensional (2D) approach that used both the Monte Carlo N-Particle Extended (MCNPX) 3D Monte Carlo code and the Discrete Ordinates Transport (DORT) two dimensional deterministic code. The analysis with proton beam energy of 1.3 GeV showed that the dose rate in continuously occupied areas on the lateral surface outside the SNS target station shielding monolith is less than 0.25 mrem/h, which compliesmore » with the SNS facility design objective. However, the methods and codes used in this analysis are out of date and unsupported, and the 2D approximation of the target shielding monolith does not accurately represent the geometry. We recommend that this analysis is updated with modern codes and libraries such as ADVANTG or SHIFT. These codes have demonstrated very high efficiency in performing full 3D radiation shielding analyses of similar and even more difficult problems.« less

Enhanced electronic and optical properties of three TMD heterobilayers.

PubMed

Rehman, Shafiq Ur; Ding, Z J

2018-06-20

The physical and chemical properties of monolayers can be tuned by selective combinations so as to be useful for device applications. Here we present a density functional theory study on the structural, electronic and optical properties of three transition metal dichalcogenide (TMD) heterobilayers, ZrS2/HfS2, ZrSe2/HfSe2 and SnS2/SnSe2. These heterobilayers are predicted to be energetically and dynamically stable structures. The band structure calculation result shows that ZrS2/HfS2, ZrSe2/HfSe2 and SnS2/SnSe2 heterobilayers are semiconductors with indirect band gaps. The efficient charge carrier separation in ZrS2/HfS2 and ZrSe2/HfSe2 heterobilayers indicates that they can be employed in energy harvesting devices. Contrary to the previous report on the ZrS2/HfS2 heterobilayer, we found it to have an intrinsic type-II band alignment which is required in p-n junction diodes and tunnel field effect transistors, and the same behavior was observed in ZrSe2/HfSe2 and SnS2/SnSe2 for the first time. The ZrS2/HfS2 and ZrSe2/HfSe2 heterobilayers reveal enhanced optical absorption both in the ultraviolet and visible regions as compared to their respective monolayers, whereas the parallel and perpendicular part of the optical absorption of the SnS2/SnSe2 heterobilayer revealed an anisotropic behavior; the perpendicular part is largely improved in the higher energy region, and the parallel part of the optical absorption is improved in the ultraviolet region.

Preclinical assessment of potential interactions between botulinum toxin and neuromodulation for bladder micturition reflex.

PubMed

Su, Xin; Nickles, Angela; Nelson, Dwight E

2015-06-09

While botulinum toxin A (BoNT-A) has become a more commonly used second-line treatment for patients with detrusor overactivity, it remains unknown whether the impacts of this therapy may persist to influence other therapies such as sacral neuromodulation. In this preclinical study we have evaluated urodynamic functions to intradetrusor injection of BoNT-A and the bladder inhibitory effects of spinal nerve stimulation (SNS) following BoNT-A treatment. Female rats were anesthetized with 3 % isoflurane. BoNT-A (2 units, 0.2 ml) or saline were injected into the detrusor. Rats then were housed for 2 days to 1 month before neuromodulation study. Monopolar electrodes were placed under each of the L6 spinal nerve bilaterally under urethane anesthesia. A bladder cannula was inserted via the urethra for saline infusion and intravesical pressure recording. Intradetrusor injection of BoNT-A for 1-2 weeks or 1 month significantly increased bladder capacity compared with saline injection (p < 0.05, two-way ANOVA). Following BoNT-A, SNS attenuated the frequency of bladder contractions, either eliminating bladder contractions or reducing the contraction frequency during electrical stimulation. Inhibition of the contraction frequency by SNS following BoNT-A treated rats was not different from that measured following saline injection. BoNT-A increased the bladder capacity, but compensating for additional saline infusion to the enlarged urinary bladder in BoNT-A pretreated rats, the bladder contractions induced by bladder filling were attenuated by SNS. BoNT-A did not alter the ability of SNS to inhibit bladder contraction following intradetrusor injection of BoNT-A for 2 days, 1-2 weeks or 1 month. These results support further pre-clinical and clinical studies to evaluate potential interactions or combination therapy with neuromodulation and intradetrusor BoNT-A therapeutic approaches.

Perceptions of Teachers and Students towards Educational Application of SNS and Its Educational Effects in Middle School Class

ERIC Educational Resources Information Center

Lee, June; Lee, Yunoug; Kim, Mi Hwa

2015-01-01

SNS use by youth is a growing trend. However, there is a lack of studies on how the application of SNS can contribute to learning and public education for youth. As SNS was not originally developed for educational purposes, there is a possibility that it can be used for meaningful educational activity or that its application can lead to the…

A fluid response: Alpha-amylase reactions to acute laboratory stress are related to sample timing and saliva flow rate.

PubMed

Nagy, Tamás; van Lien, René; Willemsen, Gonneke; Proctor, Gordon; Efting, Marieke; Fülöp, Márta; Bárdos, György; Veerman, Enno C I; Bosch, Jos A

2015-07-01

Salivary alpha-amylase (sAA) is used as a sympathetic (SNS) stress marker, though its release is likely co-determined by SNS and parasympathetic (PNS) activation. The SNS and PNS show asynchronous changes during acute stressors, and sAA responses may thus vary with sample timing. Thirty-four participants underwent an eight-minute memory task (MT) and cold pressor task (CPT). Cardiovascular SNS (pre-ejection period, blood pressure) and PNS (heart rate variability) activity were monitored continuously. Unstimulated saliva was collected repeatedly during and after each laboratory stressor, and sAA concentration (U/ml) and secretion (U/minute) determined. Both stressors increased anxiety. The MT caused an immediate and continued cardiac SNS activation, but sAA concentration increased at task cessation only (+54%); i.e., when there was SNS-PNS co-activation. During the MT sAA secretion even decreased (-35%) in conjunction with flow rate and vagal tone. The CPT robustly increased blood pressure but not sAA. In summary, sAA fluctuations did not parallel changes in cardiac SNS activity or anxiety. sAA responses seem contingent on sample timing and flow rate, likely involving both SNS and PNS influences. Verification using other stressors and contexts seems warranted. Copyright © 2015 Elsevier B.V. All rights reserved.

Recent Advances in Ultrathin Two-Dimensional Nanomaterials.

PubMed

Tan, Chaoliang; Cao, Xiehong; Wu, Xue-Jun; He, Qiyuan; Yang, Jian; Zhang, Xiao; Chen, Junze; Zhao, Wei; Han, Shikui; Nam, Gwang-Hyeon; Sindoro, Melinda; Zhang, Hua

2017-05-10

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocatalysis, batteries, supercapacitors, solar cells, photocatalysis, and sensing platforms. Finally, the challenges and outlooks in this promising field are featured on the basis of its current development.

Effective NaBH4-exfoliated ultrathin multilayer Co(OH)2 nanosheets arrays and sulfidation for energy storage

NASA Astrophysics Data System (ADS)

Yang, Wanjun; Qu, Gan; Chen, Mingyue; Ma, Wenhao; Li, Wenhui; Tang, Yiwen

2018-07-01

Facile engineering ultrathin nano structural materials is still a huge challenge for material science. Thereinto, the strategy of exfoliating shows great advantages. In this work, we develop a convenient approach to exfoliate Co(OH)2 nanosheets into ultrathin Co(OH)2 nanoflakes through NaBH4-exfoliation method. Moreover, the microstructures of the Co(OH)2 nanosheets are conveniently controlled by varying the exfoliation time. As a result, the obtained ultrathin Co(OH)2-72 h nanosheets deliver the excellent electrochemical performance. In order to improve the energy storage properties, the obtained ultrathin Co(OH)2 nanosheets are further modified to enhance the conductivity via sulfidation. Consequently, the synthesized Co(OH)2-72 h/CoS2 composites exhibit a specific capacitance of 2536 F g‑1 at 1 A g‑1, which is more outstanding than that of Co(OH)2-72 h. What’s more, the Co(OH)2-72 h/CoS2 composites show a capacitance retention of 83.3% after 10 000 cycles. Besides, the assembled asymmetric supercapacitor displays a power density of 482 W kg‑1 at an energy density of 36 Wh kg‑1, demonstrating a large potential for application.

Effective NaBH4-exfoliated ultrathin multilayer Co(OH)2 nanosheets arrays and sulfidation for energy storage.

PubMed

Yang, Wanjun; Qu, Gan; Chen, Mingyue; Ma, Wenhao; Li, Wenhui; Tang, Yiwen

2018-07-20

Facile engineering ultrathin nano structural materials is still a huge challenge for material science. Thereinto, the strategy of exfoliating shows great advantages. In this work, we develop a convenient approach to exfoliate Co(OH) 2 nanosheets into ultrathin Co(OH) 2 nanoflakes through NaBH 4 -exfoliation method. Moreover, the microstructures of the Co(OH) 2 nanosheets are conveniently controlled by varying the exfoliation time. As a result, the obtained ultrathin Co(OH) 2 -72 h nanosheets deliver the excellent electrochemical performance. In order to improve the energy storage properties, the obtained ultrathin Co(OH) 2 nanosheets are further modified to enhance the conductivity via sulfidation. Consequently, the synthesized Co(OH) 2 -72 h/CoS 2 composites exhibit a specific capacitance of 2536 F g -1 at 1 A g -1 , which is more outstanding than that of Co(OH) 2 -72 h. What's more, the Co(OH) 2 -72 h/CoS 2 composites show a capacitance retention of 83.3% after 10 000 cycles. Besides, the assembled asymmetric supercapacitor displays a power density of 482 W kg -1 at an energy density of 36 Wh kg -1 , demonstrating a large potential for application.

In times of war, adolescents do not fall silent: Teacher-student social network communication in wartime.

PubMed

Ophir, Yaakov; Rosenberg, Hananel; Asterhan, Christa S C; Schwarz, Baruch B

2016-01-01

Exposure to war is associated with psychological disturbances, but ongoing communication between adolescents and teachers may contribute to adolescents' resilience. This study examined the extent and nature of teacher-student communication on Social Network Sites (SNS) during the 2014 Israel-Gaza war. Israeli adolescents (N = 208, 13-18 yrs) completed information about SNS communication. A subset of these (N = 145) completed questionnaires on social rejection and distress sharing on SNS. More than a half (56%) of the respondents communicated with teachers via SNS. The main content category was 'emotional support'. Adolescents' perceived benefits from SNS communication with teachers were associated with distress sharing. Social rejection was negatively associated with emotional support and perceived benefits from SNS communication. We conclude that SNS communication between teachers and students may provide students with easy access to human connections and emotional support, which is likely to contribute to adolescents' resilience in times of war. Copyright © 2015 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Online social networking sites-a novel setting for health promotion?

PubMed

Loss, Julika; Lindacher, Verena; Curbach, Janina

2014-03-01

Among adolescents, online social networking sites (SNS) such as Facebook are popular platforms for social interaction and may therefore be considered as 'novel settings' that could be exploited for health promotion. In this article, we examine the relevant definitions in health promotion and literature in order to analyze whether key characteristics of 'settings for health promotion' and the socio-ecological settings approach can be transferred to SNS. As many of our daily activities have shifted to cyberspace, we argue that online social interaction may gain more importance than geographic closeness for defining a 'setting'. While exposition to positive references to risk behavior by peers may render the SNS environment detrimental to health, SNS may allow people to create their own content and therefore foster participation. However, those health promotion projects delivered on SNS up until today solely relied on health education directed at end users. It remains unclear how health promotion on SNS can meet other requirements of the settings approach (e.g. building partnerships, changing the environment). As yet, one should be cautious in terming SNS a 'setting'. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Research on Informal Learning Model of College Students Based on SNS and Case Study

NASA Astrophysics Data System (ADS)

Lu, Peng; Cong, Xiao; Bi, Fangyan; Zhou, Dongdai

2017-03-01

With the rapid development of network technology, informal learning based on online become the main way for college students to learn a variety of subject knowledge. The favor to the SNS community of students and the characteristics of SNS itself provide a good opportunity for the informal learning of college students. This research first analyzes the related research of the informal learning and SNS, next, discusses the characteristics of informal learning and theoretical basis. Then, it proposed an informal learning model of college students based on SNS according to the support role of SNS to the informal learning of students. Finally, according to the theoretical model and the principles proposed in this study, using the Elgg and related tools which is the open source SNS program to achieve the informal learning community. This research is trying to overcome issues such as the lack of social realism, interactivity, resource transfer mode in the current network informal learning communities, so as to provide a new way of informal learning for college students.

Deposition and characterization of spray pyrolysed p-type Cu2SnS3 thin film for potential absorber layer of solar cell

NASA Astrophysics Data System (ADS)

Thiruvenkadam, S.; Sakthi, P.; Prabhakaran, S.; Chakravarty, Sujay; Ganesan, V.; Rajesh, A. Leo

2018-06-01

Thin film of ternary Cu2SnS3 (CTS), a potential absorber layer for solar cells was successfully deposited by chemical spray pyrolysis technique. The GIXRD pattern revealed that the film having tetragonal Cu2SnS3 phase with the preferential orientation along (112), (200), (220) and (312) plane and it is further confirmed using Raman spectroscopy by the existence of Raman peak at 320 cm-1. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 28.8 nm. The absorption coefficient was found to be greater than the order of 105 cm-1 and bandgap of 1.70 eV. Hall effect measurement indicates the p type nature of the film with a hole concentration of 1.03 × 1016cm-3 and a hall mobility of 404 cm2/V. The properties of CTS thin film confirmed suitable to be a potential absorber layer material for photovoltaic applications.

Synthesis and Size Dependent Reflectance Study of Water Soluble SnS Nanoparticles

PubMed Central

Xu, Ying; Al-Salim, Najeh; Tilley, Richard D.

2012-01-01

Near-monodispersed water soluble SnS nanoparticles in the diameter range of 3–6 nm are synthesized by a facile, solution based one-step approach using ethanolamine ligands. The optimal amount of triethanolamine is investigated. The effect of further heat treatment on the size of these SnS nanoparticles is discussed. Diffuse reflectance study of SnS nanoparticles agrees with predictions from quantum confinement model. PMID:28348295

Older adolescents' motivations for social network site use: the influence of gender, group identity, and collective self-esteem.

PubMed

Barker, Valerie

2009-04-01

This study assessed motives for social network site (SNS) use, group belonging, collective self-esteem, and gender effects among older adolescents. Communication with peer group members was the most important motivation for SNS use. Participants high in positive collective self-esteem were strongly motivated to communicate with peer group via SNS. Females were more likely to report high positive collective self-esteem, greater overall use, and SNS use to communicate with peers. Females also posted higher means for group-in-self, passing time, and entertainment. Negative collective self-esteem correlated with social compensation, suggesting that those who felt negatively about their social group used SNS as an alternative to communicating with other group members. Males were more likely than females to report negative collective self-esteem and SNS use for social compensation and social identity gratifications.

Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon

2011-07-15

Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainlymore » comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.« less

Separate and shared sympathetic outflow to white and brown fat coordinately regulates thermoregulation and beige adipocyte recruitment

PubMed Central

Nguyen, Ngoc Ly T.; Barr, Candace L.; Ryu, Vitaly; Cao, Qiang; Bartness, Timothy J.

2017-01-01

White adipose tissue (WAT) and brown adipose tissue (BAT) are innervated and regulated by the sympathetic nervous system (SNS). It is not clear, however, whether there are shared or separate central SNS outflows to WAT and BAT that regulate their function. We injected two isogenic strains of pseudorabies virus, a retrograde transneuronal viral tract tracer, with unique fluorescent reporters into interscapular BAT (IBAT) and inguinal WAT (IWAT) of the same Siberian hamsters to define SNS pathways to both. To test the functional importance of SNS coordinated control of BAT and WAT, we exposed hamsters with denervated SNS nerves to IBAT to 4°C for 16–24 h and measured core and fat temperatures and norepinephrine turnover (NETO) and uncoupling protein 1 (UCP1) expression in fat tissues. Overall, there were more SNS neurons innervating IBAT than IWAT across the neuroaxis. However, there was a greater percentage of singly labeled IWAT neurons in midbrain reticular nuclei than singly labeled IBAT neurons. The hindbrain had ~30–40% of doubly labeled neurons while the forebrain had ~25% suggesting shared SNS circuitry to BAT and WAT across the brain. The raphe nucleus, a key region in thermoregulation, had ~40% doubly labeled neurons. Hamsters with IBAT SNS denervation maintained core body temperature during acute cold challenge and had increased beige adipocyte formation in IWAT. They also had increased IWAT NETO, temperature, and UCP1 expression compared with intact hamsters. These data provide strong neuroanatomical and functional evidence of WAT and BAT SNS cross talk for thermoregulation and beige adipocyte formation. PMID:27881398

Far-infrared study of the mechanochemically synthesized Cu2FeSnS4 (stannite) nanocrystals

NASA Astrophysics Data System (ADS)

Trajic, J.; Romcevic, M.; Paunovic, N.; Curcic, M.; Balaz, P.; Romcevic, N.

2018-05-01

The analysis of the optical properties of mechanochemically synthesized stannite Cu2FeSnS4 nanocrystals has been performed using far-infrared spectroscopy. The Cu2FeSnS4 stannite nanocrystals were synthesized mechanochemically from elemental precursors Cu, Fe, Sn, and S. Milling time was 45, 60, 90 and 120 min. Reflectivity spectra were analyzed using the classical form of the dielectric function, which includes the phonon and the free carrier contribution. The influence of milling time on synthesis of stannite Cu2FeSnS4 is observed. Among the modes that are characteristic for the stannite Cu2FeSnS4, we registered the modes of binary phases of FeS and SnS. The total disappearance of the binary phases of FeS and SnS and forming pure Cu2FeSnS4 is observed when the milling time is 120 min. Effective permittivity of Cu2FeSnS4 and binary phases of FeS and SnS were modeled by Maxwell - Garnet approximation.

CVD synthesis of large-area, highly crystalline MoSe2 atomic layers on diverse substrates and application to photodetectors.

PubMed

Xia, Jing; Huang, Xing; Liu, Ling-Zhi; Wang, Meng; Wang, Lei; Huang, Ben; Zhu, Dan-Dan; Li, Jun-Jie; Gu, Chang-Zhi; Meng, Xiang-Min

2014-08-07

Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ∼ 1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ∼ 60 ms and a good photoresponsivity of ∼ 13 mA/W (using a 532 nm laser at an intensity of 1 mW mm(-2) and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications.

Few-layered CoHPO4.3H2O ultrathin nanosheets for high performance of electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Pang, Huan; Wang, Shaomei; Shao, Weifang; Zhao, Shanshan; Yan, Bo; Li, Xinran; Li, Sujuan; Chen, Jing; Du, Weimin

2013-06-01

Ultrathin cobalt phosphate (CoHPO4.3H2O) nanosheets are successfully synthesized by a one pot hydrothermal method. Novel CoHPO4.3H2O ultrathin nanosheets are assembled for constructing the electrodes of supercapacitors. Benefiting from the nanostructures, the as-prepared electrode shows a specific capacitance of 413 F g-1, and no obvious decay even after 3000 charge-discharge cycles. Such a quasi-two-dimensional material is a new kind of supercapacitor electrode material with high performance.Ultrathin cobalt phosphate (CoHPO4.3H2O) nanosheets are successfully synthesized by a one pot hydrothermal method. Novel CoHPO4.3H2O ultrathin nanosheets are assembled for constructing the electrodes of supercapacitors. Benefiting from the nanostructures, the as-prepared electrode shows a specific capacitance of 413 F g-1, and no obvious decay even after 3000 charge-discharge cycles. Such a quasi-two-dimensional material is a new kind of supercapacitor electrode material with high performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01460f

Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

NASA Astrophysics Data System (ADS)

Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

2017-06-01

Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

Ultralow-loss polaritons in isotopically pure boron nitride.

PubMed

Giles, Alexander J; Dai, Siyuan; Vurgaftman, Igor; Hoffman, Timothy; Liu, Song; Lindsay, Lucas; Ellis, Chase T; Assefa, Nathanael; Chatzakis, Ioannis; Reinecke, Thomas L; Tischler, Joseph G; Fogler, Michael M; Edgar, J H; Basov, D N; Caldwell, Joshua D

2018-02-01

Conventional optical components are limited to size scales much larger than the wavelength of light, as changes to the amplitude, phase and polarization of the electromagnetic fields are accrued gradually along an optical path. However, advances in nanophotonics have produced ultrathin, so-called 'flat' optical components that beget abrupt changes in these properties over distances significantly shorter than the free-space wavelength. Although high optical losses still plague many approaches, phonon polariton (PhP) materials have demonstrated long lifetimes for sub-diffractional modes in comparison to plasmon-polariton-based nanophotonics. We experimentally observe a threefold improvement in polariton lifetime through isotopic enrichment of hexagonal boron nitride (hBN). Commensurate increases in the polariton propagation length are demonstrated via direct imaging of polaritonic standing waves by means of infrared nano-optics. Our results provide the foundation for a materials-growth-directed approach aimed at realizing the loss control necessary for the development of PhP-based nanophotonic devices.

Magnetic Iron Oxide Nanowires Formed by Reactive Dewetting.

PubMed

Bennett, Roger A; Etman, Haitham A; Hicks, Hannah; Richards, Leah; Wu, Chen; Castell, Martin R; Dhesi, Sarnjeet S; Maccherozzi, Francesco

2018-04-11

The growth and reactive dewetting of ultrathin films of iron oxides supported on Re(0001) surfaces have been imaged in situ in real time. Initial growth forms a nonmagnetic stable FeO (wüstite like) layer in a commensurate network upon which high aspect ratio nanowires of several microns in length but less than 40 nm in width can be fabricated. The nanowires are closely aligned with the substrate crystallography and imaging by X-ray magnetic circular dichroism shows that each contain a single magnetic domain. The driving force for dewetting appears to be the minimization of strain energy of the Fe 3 O 4 crystallites and follows the Tersoff and Tromp model in which strain is minimized at constant height by extending in one epitaxially matched direction. Such wires are promising in spintronic applications and we predict that the growth will also occur on other hexagonal substrates.

Ultralow-loss polaritons in isotopically pure boron nitride

NASA Astrophysics Data System (ADS)

Giles, Alexander J.; Dai, Siyuan; Vurgaftman, Igor; Hoffman, Timothy; Liu, Song; Lindsay, Lucas; Ellis, Chase T.; Assefa, Nathanael; Chatzakis, Ioannis; Reinecke, Thomas L.; Tischler, Joseph G.; Fogler, Michael M.; Edgar, J. H.; Basov, D. N.; Caldwell, Joshua D.

2018-02-01

Conventional optical components are limited to size scales much larger than the wavelength of light, as changes to the amplitude, phase and polarization of the electromagnetic fields are accrued gradually along an optical path. However, advances in nanophotonics have produced ultrathin, so-called `flat' optical components that beget abrupt changes in these properties over distances significantly shorter than the free-space wavelength. Although high optical losses still plague many approaches, phonon polariton (PhP) materials have demonstrated long lifetimes for sub-diffractional modes in comparison to plasmon-polariton-based nanophotonics. We experimentally observe a threefold improvement in polariton lifetime through isotopic enrichment of hexagonal boron nitride (hBN). Commensurate increases in the polariton propagation length are demonstrated via direct imaging of polaritonic standing waves by means of infrared nano-optics. Our results provide the foundation for a materials-growth-directed approach aimed at realizing the loss control necessary for the development of PhP-based nanophotonic devices.

Social media in health professional education: a student perspective on user levels and prospective applications.

PubMed

Maloney, Stephen; Moss, Alan; Ilic, Dragan

2014-12-01

Social Networking Sites (SNS) have seen exponential growth in recent years. The high utilisation of SNS by tertiary students makes them an attractive tool for educational institutions. This study aims to identify health professional students' use and behaviours with SNS, including students' perspectives on potential applications within health professional curricula. Students enrolled in an undergraduate physiotherapy program were invited to take part in an anonymous, online questionnaire at the end of 2012. The survey consisted of 20 items, gathering demographic data, information on current use of SNS, and opinions regarding the application of SNS into education. Both quantitative and qualitative data were gathered. A total of 142 students, from all years of study, completed the online questionnaire. Only two participants were not current users of social media. Facebook and YouTube had been utilised for educational purposes by 97 and 60 % of participants respectively; 85 % believed that SNS could benefit their learning experience. Only five respondents were not interested in following peers, academic staff, clinicians or professional associations on Facebook. Four key themes emerged: peer collaboration, need for separation between personal and professional realms, complimentary learning and enhanced communication. Students wish to make educational connections via SNS, yet expressed a strong desire to maintain privacy, and a distinction between personal and professional lives. Educational utilisation of SNS may improve communication speed and accessibility. Any educator involvement should be viewed with caution.

Online social networking addiction among college students in Singapore: Comorbidity with behavioral addiction and affective disorder.

PubMed

Tang, Catherine So-Kum; Koh, Yvaine Yee Woen

2017-02-01

This study aimed to determine the prevalence of addiction to social networking sites/platforms (SNS) and its comorbidity with other behavioral addiction and affective disorder among college students in Singapore. 1110 college students (age: M=21.46, SD=1.80) in Singapore completed measures assessing online social networking, unhealthy food intake and shopping addiction as well as depression, anxiety and mania. Descriptive analyses were conducted to investigate the prevalence and comorbidity of behavioral addiction and affective disorder. Chi-square tests were used to examine gender differences. The prevalence rates of SNS, food and shopping addiction were 29.5%, 4.7% and 9.3% respectively for the total sample. SNS addiction was found to co-occur with food addiction (3%), shopping addiction (5%), and both food and shopping addiction (1%). The comorbidity rates of SNS addiction and affective disorder were 21% for depression, 27.7% for anxiety, and 26.1% for mania. Compared with the total sample, students with SNS addiction reported higher comorbidity rates with other behavioral addiction and affective disorder. In general, females as compared to males reported higher comorbidity rates of SNS addiction and affective disorder. SNS addiction has a high prevalence rate among college students in Singapore. Students with SNS addiction were vulnerable to experience other behavior addiction as well as affective disorder, especially among females. Copyright © 2016. Published by Elsevier B.V.

Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart.

PubMed

Winter, James; Bishop, Martin J; Wilder, Catherine D E; O'Shea, Christopher; Pavlovic, Davor; Shattock, Michael J

2018-01-01

Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS. Objective : To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated. Methods and Results : Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In contrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (I Ks ), sufficient to abolish I Ks -mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake into the sarcoplasmic reticulum is a major mechanism by which SNS suppresses alternans in the guinea pig heart. Conclusions : SNS suppresses calcium and action potential alternans in the intact guinea pig heart by an action mediated through accelerated Ca handling and via increased I Ks .

Sulfide semiconductor materials prepared by high-speed electrodeposition and discussion of electrochemical reaction mechanism

NASA Astrophysics Data System (ADS)

Okamoto, Naoki; Kataoka, Kentaro; Saito, Takeyasu

2017-07-01

A manufacturing method for SnS using a one-step electrochemical technique was developed. The sulfide semiconductor was formed by electrodeposition using an aqueous bath at low temperatures. The sulfide semiconductor particles produced were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The highest current density at which SnS was formed was 1800 mA/cm2 at a bath temperature of 293 K, which is 36 times larger than that in a previous deposition process. Analysis of the chronoamperometric current-time transients indicated that in the potential range from -1100 to -2000 mV vs saturated calomel electrode (SCE), the electrodeposition of SnS can be explained by an instantaneous nucleation model.

In Situ Ramp Anneal X-ray Diffraction Study of Atomic Layer Deposited Ultrathin TaN and Ta 1-x Al x N y Films for Cu Diffusion Barrier Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Consiglio, S.; Dey, S.; Yu, K.

2016-01-01

Ultrathin TaN and Ta 1-xAl xN y films with x = 0.21 to 0.88 were deposited by atomic layer deposition (ALD) and evaluated for Cu diffusion barrier effectiveness compared to physical vapor deposition (PVD) grown TaN. Cu diffusion barrier effectiveness was investigated using in-situ ramp anneal synchrotron X-ray diffraction (XRD) on Cu/1.8 nm barrier/Si stacks. A Kissinger-like analysis was used to assess the kinetics of Cu 3Si formation and determine the effective activation energy (E a) for Cu silicidation. Compared to the stack with a PVD TaN barrier, the stacks with the ALD films exhibited a higher crystallization temperature (Tmore » c) for Cu silicidation. The Ea values of Cu 3Si formation for stacks with the ALD films were close to the reported value for grain boundary diffusion of Cu whereas the Ea of Cu 3Si formation for the stack with PVD TaN is closer to the reported value for lattice diffusion. For 3 nm films, grazing incidence in-plane XRD showed evidence of nanocrystallites in an amorphous matrix with broad peaks corresponding to high density cubic phase for the ALD grown films and lower density hexagonal phase for the PVD grown film further elucidating the difference in initial failure mechanisms due to differences in barrier crystallinity and associated phase.« less

Fast Monte Carlo simulation of a dispersive sample on the SEQUOIA spectrometer at the SNS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Granroth, Garrett E; Chen, Meili; Kohl, James Arthur

2007-01-01

Simulation of an inelastic scattering experiment, with a sample and a large pixilated detector, usually requires days of time because of finite processor speeds. We report simulations on an SNS (Spallation Neutron Source) instrument, SEQUOIA, that reduce the time to less than 2 hours by using parallelization and the resources of the TeraGrid. SEQUOIA is a fine resolution (∆E/Ei ~ 1%) chopper spectrometer under construction at the SNS. It utilizes incident energies from Ei = 20 meV to 2 eV and will have ~ 144,000 detector pixels covering 1.6 Sr of solid angle. The full spectrometer, including a 1-D dispersivemore » sample, has been simulated using the Monte Carlo package McStas. This paper summarizes the method of parallelization for and results from these simulations. In addition, limitations of and proposed improvements to current analysis software will be discussed.« less

Nurse-led epistaxis management within the emergency department.

PubMed

Hakim, Navid; Mummadi, Sangha Mitra; Jolly, Karan; Dawson, Julian; Darr, Adnan

2018-01-11

the incidence of epistaxis has increased secondary to increased life expectancy and morbidities. This study sought to assess the knowledge, practice and opinion relating to adequacy of training of advanced nurse practitioners (ANPs) and staff nurses (SNs) in the emergency department. a national survey was distributed over an 8-week period; this included a 3-point scoring system based on the National Institute for Health and Care Excellence Clinical Knowledge Summaries guidance on epistaxis management to assess overall performance. analysis included 109 ANPs and 101 SNs; 12% of ANPs achieved the maximum score, 40% scored 2, 25% scored 1, and 23% scored 0, while 14% of SNs achieved the maximum score, 24% scored 2, 29% scored 1, and 32% scored 0. Overall 88% of respondents advocated further training. significant deficits in knowledge regarding epistaxis management were highlighted. Further training could help to empower patients in basic first aid measures, subsequently reducing admissions rates.

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

Help, I Am Losing Control! Examining the Reporting of Sexual Harassment by Adolescents to Social Networking Sites.

PubMed

Van Royen, Kathleen; Poels, Karolien; Vandebosch, Heidi

2016-01-01

Sexual harassment is often encountered by adolescents on social networking sites (SNS). One option to cope with a situation of harassment on SNS is to alarm the provider by reporting the transgressive content. It is yet unclear what the determinants of reporting a sexual harassment situation on SNS are, as well as the subsequent actions to these reports from the part of the SNS provider. In this article, we seek to address these gaps, and in particular examine whether control-by-the-self over the situation and negative emotions play a role in the reporting of sexual harassment on SNS. Findings indicate that a low situational control-by-the-self, indirectly (namely through a higher experience of negative emotions such as anger and shame) increases the reporting of sexual harassment by the victim. Public visibility of the incident and the impossibility to remove the content reduce the situational control-by-the-self. Results further suggest that SNS providers often ignore reported situations of sexual harassment. The study concludes with suggestions for responses to reported harassment on SNS, which should be directed toward increasing behavioral control and thereby alleviating negative emotions.

Soft neurological signs in childhood by measurement of arm movements using acceleration and angular velocity sensors.

PubMed

Kaneko, Miki; Yamashita, Yushiro; Inomoto, Osamu; Iramina, Keiji

2015-10-12

Soft neurological signs (SNS) are evident in the motor performance of children and disappear as the child grows up. Therefore SNS are used as criteria for evaluating age-appropriate development of neurological function. The aim of this study was to quantify SNS during arm movement in childhood. In this study, we focused on pronation and supination, which are arm movements included in the SNS examination. Two hundred and twenty-three typically developing children aged 4-12 years (107 boys, 116 girls) and 18 adults aged 21-26 years (16 males, two females) participated in the experiment. To quantify SNS during pronation and supination, we calculated several evaluation index scores: bimanual symmetry, compliance, postural stability, motor speed and mirror movement. These index scores were evaluated using data obtained from sensors attached to the participants' hands and elbows. Each score increased as age increased. Results obtained using our system showed developmental changes that were consistent with criteria for SNS. We were able to successfully quantify SNS during pronation and supination. These results indicate that it may be possible to use our system as quantitative criteria for evaluating development of neurological function.

(abstract) High-T(sub c) SNS Weak Links Using Oxide Normal Metals

NASA Technical Reports Server (NTRS)

Hunt, B. D.; Barner, J. B.; Foote, M. C.; Vasquez, R. P.

1993-01-01

This work examines device results for edge-geometry SNS weak links utilizing a variety of oxide normal metals. A comparison of the electrical properties of fabricated devices and the magnetic field response will be presented. Device reproducibility will also be discussed. This talk will also examine recent progress in fabrication of epitaxial SNS weak links on silicon-on-sapphire (SOS) substrates. SNS weak links fabricated recently are under investigation, and preliminary results on these devices will be discussed.

Risk of Subsequent Neoplasms During the Fifth and Sixth Decades of Life in the Childhood Cancer Survivor Study Cohort.

PubMed

Turcotte, Lucie M; Whitton, John A; Friedman, Debra L; Hammond, Sue; Armstrong, Gregory T; Leisenring, Wendy; Robison, Leslie L; Neglia, Joseph P

2015-11-01

Survivors of childhood cancer have an increased risk for subsequent neoplasms (SNs), but the incidence beyond the age of 40 years and associations with therapeutic exposures have not been well described. Among 14,364 survivors of childhood cancer diagnosed between 1970 and 1986, 3,171 had an attained age of 40 years or older at the time of last contact. Cumulative incidence of SNs, standardized incidence ratios (SIRs), excess absolute risk of subsequent malignant neoplasms (SMNs), and relative risks (RRs) for SMNs and nonmelanoma skin cancers were calculated. In total, 679 SNs were diagnosed in patients age 40 years or older. These included 196 SMNs, 419 nonmelanoma skin cancers, 21 nonmalignant meningiomas, and 43 other benign neoplasms. At age 55 years, the cumulative incidence of new SNs and SMNs occurring after age 40 years was 34.6% (95% CI, 28.7 to 40.6) and 16.3% (95% CI, 11.7 to 20.9), respectively. Survivors were twice as likely as the general population to receive a diagnosis of SMN after age 40 years (SIR, 2.2; 95% CI, 1.9 to 2.5). Among SMNs, risk was increased for breast cancer (SIR, 5.5; 95% CI, 4.5 to 6.7), renal cancer (SIR, 3.9; 95% CI, 2.0 to 7.5), soft tissue sarcoma (SIR, 2.6; 95% CI, 1.5 to 4.4), and thyroid cancer (SIR, 1.9; 95% CI, 1.0 to 3.5). Female sex (RR, 1.9; 95% CI, 1.3 to 2.6; P < .001) and therapeutic radiation exposure (RR, 2.2; 95% CI, 1.4 to 3.3; P < .001) were associated with an increased for risk for SMN in multivariable analysis. Even after age 40 years, survivors of childhood cancer remain at increased risk for treatment-related SNs. These data suggest the need for life-long monitoring and should inform anticipatory guidance provided to survivors of childhood cancer. © 2015 by American Society of Clinical Oncology.

Risk of Subsequent Neoplasms During the Fifth and Sixth Decades of Life in the Childhood Cancer Survivor Study Cohort

PubMed Central

Turcotte, Lucie M.; Whitton, John A.; Friedman, Debra L.; Hammond, Sue; Armstrong, Gregory T.; Leisenring, Wendy; Robison, Leslie L.; Neglia, Joseph P.

2015-01-01

Purpose Survivors of childhood cancer have an increased risk for subsequent neoplasms (SNs), but the incidence beyond the age of 40 years and associations with therapeutic exposures have not been well described. Patients and Methods Among 14,364 survivors of childhood cancer diagnosed between 1970 and 1986, 3,171 had an attained age of 40 years or older at the time of last contact. Cumulative incidence of SNs, standardized incidence ratios (SIRs), excess absolute risk of subsequent malignant neoplasms (SMNs), and relative risks (RRs) for SMNs and nonmelanoma skin cancers were calculated. Results In total, 679 SNs were diagnosed in patients age 40 years or older. These included 196 SMNs, 419 nonmelanoma skin cancers, 21 nonmalignant meningiomas, and 43 other benign neoplasms. At age 55 years, the cumulative incidence of new SNs and SMNs occurring after age 40 years was 34.6% (95% CI, 28.7 to 40.6) and 16.3% (95% CI, 11.7 to 20.9), respectively. Survivors were twice as likely as the general population to receive a diagnosis of SMN after age 40 years (SIR, 2.2; 95% CI, 1.9 to 2.5). Among SMNs, risk was increased for breast cancer (SIR, 5.5; 95% CI, 4.5 to 6.7), renal cancer (SIR, 3.9; 95% CI, 2.0 to 7.5), soft tissue sarcoma (SIR, 2.6; 95% CI, 1.5 to 4.4), and thyroid cancer (SIR, 1.9; 95% CI, 1.0 to 3.5). Female sex (RR, 1.9; 95% CI, 1.3 to 2.6; P < .001) and therapeutic radiation exposure (RR, 2.2; 95% CI, 1.4 to 3.3; P < .001) were associated with an increased for risk for SMN in multivariable analysis. Conclusion Even after age 40 years, survivors of childhood cancer remain at increased risk for treatment-related SNs. These data suggest the need for life-long monitoring and should inform anticipatory guidance provided to survivors of childhood cancer. PMID:26261260

A Cross-Cultural Examination of SNS Usage Intensity and Managing Interpersonal Relationships Online: The Role of Culture and the Autonomous-Related Self-Construal.

PubMed

Lee, Soon Li; Kim, Jung-Ae; Golden, Karen Jennifer; Kim, Jae-Hwi; Park, Miriam Sang-Ah

2016-01-01

Perception of the autonomy and relatedness of the self may be influenced by one's experiences and social expectations within a particular cultural setting. The present research examined the role of culture and the Autonomous-Related self-construal in predicting for different aspects of Social Networking Sites (SNS) usage in three Asian countries, especially focusing on those aspects serving interpersonal goals. Participants in this cross-cultural study included 305 university students from Malaysia (n = 105), South Korea (n = 113), and China (n = 87). The study explored specific social and interpersonal behaviors on SNS, such as browsing the contacts' profiles, checking for updates, and improving contact with SNS contacts, as well as the intensity of SNS use, hypothesizing that those with high intensity of use in the Asian context may be doing so to achieve the social goal of maintaining contact and keeping updated with friends. Two scales measuring activities on other users' profiles and contact with friends' profiles were developed and validated. As predicted, some cross-cultural differences were found. Koreans were more likely to use SNS to increase contact but tended to spend less time browsing contacts' profiles than the Malaysians and Chinese. The intensity of SNS use differed between the countries as well, where Malaysians reported higher intensity than Koreans and Chinese. Consistent with study predictions, Koreans were found with the highest Autonomous-Related self-construal scores. The Autonomous-Related self-construal predicted SNS intensity. The findings suggest that cultural contexts, along with the way the self is construed in different cultures, may encourage different types of SNS usage. The authors discuss study implications and suggest future research directions.

A Cross-Cultural Examination of SNS Usage Intensity and Managing Interpersonal Relationships Online: The Role of Culture and the Autonomous-Related Self-Construal

PubMed Central

Lee, Soon Li; Kim, Jung-Ae; Golden, Karen Jennifer; Kim, Jae-Hwi; Park, Miriam Sang-Ah

2016-01-01

Perception of the autonomy and relatedness of the self may be influenced by one's experiences and social expectations within a particular cultural setting. The present research examined the role of culture and the Autonomous-Related self-construal in predicting for different aspects of Social Networking Sites (SNS) usage in three Asian countries, especially focusing on those aspects serving interpersonal goals. Participants in this cross-cultural study included 305 university students from Malaysia (n = 105), South Korea (n = 113), and China (n = 87). The study explored specific social and interpersonal behaviors on SNS, such as browsing the contacts' profiles, checking for updates, and improving contact with SNS contacts, as well as the intensity of SNS use, hypothesizing that those with high intensity of use in the Asian context may be doing so to achieve the social goal of maintaining contact and keeping updated with friends. Two scales measuring activities on other users' profiles and contact with friends' profiles were developed and validated. As predicted, some cross-cultural differences were found. Koreans were more likely to use SNS to increase contact but tended to spend less time browsing contacts' profiles than the Malaysians and Chinese. The intensity of SNS use differed between the countries as well, where Malaysians reported higher intensity than Koreans and Chinese. Consistent with study predictions, Koreans were found with the highest Autonomous-Related self-construal scores. The Autonomous-Related self-construal predicted SNS intensity. The findings suggest that cultural contexts, along with the way the self is construed in different cultures, may encourage different types of SNS usage. The authors discuss study implications and suggest future research directions. PMID:27148100

Dielectric and modulus analysis of the photoabsorber Cu2SnS3

NASA Astrophysics Data System (ADS)

Lahlali, S.; Essaleh, L.; Belaqziz, M.; Chehouani, H.; Alimoussa, A.; Djessas, K.; Viallet, B.; Gauffier, J. L.; Cayez, S.

2017-12-01

Dielectric properties of the ternary semiconductor compound Cu2SnS3 is studied for the first time in the high temperature range from 300 °C to 440 °C with the frequency range 1 kHz to 1 MHz. The dielectric constant ε ‧ and dielectric loss tan (δ) were observed to increase with temperature and decrease rapidly with frequency to remains constant at high frequencies. The variation of the dielectric loss Ln (ε ") with L n (ω) was found to follow the empirical law, ε " = B ω m (T). The dielectric data were analyzed using complex electrical modulus M* at various temperatures. The activation energy responsible for the relaxation is estimated from the analysis of the modulus spectra. The value of the hopping barrier potential is estimated from the dielectric loss and compared with the value previously obtained from ac-conductivity. These results are critical for understanding the behavior of based polycrystalline family of Cu2SnS3 for absorber materials in solar-cells.

Social instability and immunity in rhesus monkeys: the role of the sympathetic nervous system.

PubMed

Capitanio, John P; Cole, Steven W

2015-05-26

Social instability can adversely affect endocrine, immune and health outcomes, and recent evidence suggests that the sympathetic nervous system (SNS) might mediate these effects. We conducted two studies with adult male rhesus monkeys (Macaca mulatta) to understand how social conditions affect measures of SNS activity and immune function. In Experiment 1, animals were socialized in stable social conditions, then were switched to unstable (stressful) social conditions, then were returned to stable conditions. Analysis revealed quadratic effects for measures of behaviour, urinary metabolites of epinephrine and norepinephrine, and expression of immune response genes: as expected, social instability adversely impacted most measures, and the effects remediated upon re-imposition of stable conditions. Cortisol levels were unaffected. In Experiment 2, we used the sympathomimetic drug methamphetamine to challenge the SNS; animals also underwent socialization in stable or unstable groups. Surprisingly, while methamphetamine elevated plasma catecholamines, responses in lymph nodes tracked the social, and not the drug, condition: social instability upregulated the density of SNS fibres in lymph nodes and downregulated Type I interferon gene expression. Together, these results indicate that the SNS is extremely sensitive to social conditions; full understanding of the adverse effects of social instability on health should therefore incorporate measures of this health-relevant system. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Neuroticism Magnifies the Detrimental Association between Social Media Addiction Symptoms and Wellbeing in Women, but Not in Men: a three-Way Moderation Model.

PubMed

Turel, Ofir; Poppa, Natalie Tasha; Gil-Or, Oren

2018-02-03

Addiction symptoms in relation to the use of social networking sites (SNS) can be associated with reduced wellbeing. However, the mechanisms that can control this association have not been fully characterized, despite their relevance to effective treatment of individuals presenting SNS addiction symptoms. In this study we hypothesize that sex and neuroticism, which are important determinants of how people evaluate and respond to addiction symptoms, moderate this association. To examine these assertions, we employed hierarchical linear and logistic regression techniques to analyze data collected with a cross-sectional survey of 215 Israeli college students who use SNS. Results lend support to the hypothesized negative association between SNS addiction symptoms and wellbeing (as well as potentially being at-risk for low mood/ mild depression), and the ideas that (1) this association is augmented by neuroticism, and (2) that the augmentation is stronger for women than for men. They demonstrated that the sexes may differ in their SNS addiction-wellbeing associations: while men had similar addiction symptoms -wellbeing associations across neuroticism levels, women with high levels of neuroticism presented much steeper associations compared to women with low neuroticism. This provides an interesting account of possible "telescoping effect", the idea that addicted women present a more severe clinical profile compared to men, in the case of technology-"addictions".

Synthesis of tin monosulfide (SnS) nanoparticles using surfactant free microemulsion (SFME) with the single microemulsion scheme

NASA Astrophysics Data System (ADS)

Tarkas, Hemant S.; Marathe, Deepak M.; Mahajan, Mrunal S.; Muntaser, Faisal; Patil, Mahendra B.; Tak, Swapnil R.; Sali, Jaydeep V.

2017-02-01

Synthesis of monomorphic, SnS nanoparticles without using a capping agent is a difficult task with chemical route of synthesis. This paper reports on synthesis of tin monosulfide (SnS) nanopartilces with dimension in the quantum-dot regime using surfactant free microemulsion with single microemulsion scheme. This has been achieved by reaction in microreactors in the CME (C: chlorobenzene, M: methanol and E: ethylene glycol) microemulsion system. This is an easy and controllable chemical route for synthesis of SnS nanoparticles. Nanoparticle diameter showed prominent dependence on microemulsion concentration and marginal dependence on microemulsion temperature in the temperature range studied. The SnS nanoparticles formed with this method form stable dispersion in Tolune.

Taking stress response out of the box: stability, discontinuity, and temperament effects on HPA and SNS across social stressors in mother-infant dyads.

PubMed

Laurent, Heidemarie K; Ablow, Jennifer C; Measelle, Jeffrey

2012-01-01

This study investigated continuity and stability of hypothalamic-pituitary-adrenal (HPA) and sympathetic nervous system (SNS) response measures in mother-infant dyads across 2 different types of social stress sessions. Synchrony of response trajectories across systems (SNS-HPA coordination) and partners (mother-infant attunement) was addressed, as were associations with infant temperament. Primiparous mothers and their 18-month-old infants (n = 86 dyads) completed an attachment stressor--Strange Situation (Ainsworth, Blehar, Waters, & Wall, 1978)--at Session 1 and challenge stressors--cleanup task and emotion task battery--at Session 2. Mother and infant saliva samples collected to index pre-stress, stress, and post-stress response during each session were assayed for cortisol (HPA marker) and salivary alpha-amylase (sAA; SNS marker). Multilevel modeling of cortisol/sAA trajectories across sessions revealed rank-order stability in mother/infant stress measures but discontinuity in absolute levels; cortisol trajectories were higher during attachment stress, and sAA trajectories were higher during challenge stress. Varying degrees of mother-infant attunement were found across sessions/systems. Infant surgency predicted higher stress measures, and negative affect and effortful control predicted lower stress measures, though associations depended on session/system. Findings are discussed in terms of advancing a multisystemic, contextual definition of developing stress responsiveness.

Is use of social networking sites associated with young women's body dissatisfaction and disordered eating? A look at Black-White racial differences.

PubMed

Howard, Lindsay M; Heron, Kristin E; MacIntyre, Rachel I; Myers, Taryn A; Everhart, Robin S

2017-12-01

Maladaptive patterns of social networking site (SNS) use, such as excessive reassurance seeking, are associated with body dissatisfaction and disordered eating. However, it is unclear how these processes play out among different racial groups. This study examined racial differences in SNS use and body dissatisfaction and disordered eating. Black (n=445) and White (n=477) female undergraduates completed online measures of SNS use (frequency and reassurance seeking), body dissatisfaction, and disordered eating. Black women reported less body dissatisfaction, marginally less disordered eating, and less frequent Facebook use than White women; there were no race differences in SNS reassurance seeking. More frequent Facebook use was associated with more body dissatisfaction (but not disordered eating), and more SNS reassurance seeking predicted both more body dissatisfaction and disordered eating. Associations were not moderated by race, suggesting maladaptive SNS use may have negative consequences for both Black and White women. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Relationship Between Online Social Network Use, Sexual Risk Behaviors, and HIV Sero-Status Among a Sample of Predominately African American and Latino Men Who have Sex with Men (MSM) Social Media Users.

PubMed

Chiu, ChingChe J; Young, Sean D

2015-06-01

Social networking technologies have emerged as potential platforms to reach HIV(+) MSM in HIV interventions. This study sought to compare use of online social networking sites (SNSs) and sexual risk behaviors between HIV(+) and HIV(-) individuals among a sample of predominately African American and Latino SNS-using MSM. A total of 112 MSM Facebook users were recruited online and offline and completed an online survey. We performed regression models to assess the association between HIV status, SNS use, and sexual risk behaviors. After adjusting for age, race, and employment status, being HIV positive was significantly associated with a greater number of sexual partners (ARR = 2.84, p = 0.0017) and lower comfort levels of discussing HIV/STI status on SNSs (AOR: 0.23, p = 0.011). Findings suggest that HIV status is associated with sexual risk behaviors and SNS use among SNS-using MSM. We discuss the implications for online HIV prevention.

Potential benefits and harms of a peer support social network service on the internet for people with depressive tendencies: qualitative content analysis and social network analysis.

PubMed

Takahashi, Yoshimitsu; Uchida, Chiyoko; Miyaki, Koichi; Sakai, Michi; Shimbo, Takuro; Nakayama, Takeo

2009-07-23

Internet peer support groups for depression are becoming popular and could be affected by an increasing number of social network services (SNSs). However, little is known about participant characteristics, social relationships in SNSs, and the reasons for usage. In addition, the effects of SNS participation on people with depression are rather unknown. The aim was to explore the potential benefits and harms of an SNS for depression based on a concurrent triangulation design of mixed methods strategy, including qualitative content analysis and social network analysis. A cross-sectional Internet survey of participants, which involved the collection of SNS log files and a questionnaire, was conducted in an SNS for people with self-reported depressive tendencies in Japan in 2007. Quantitative data, which included user demographics, depressive state, and assessment of the SNS (positive vs not positive), were statistically analyzed. Descriptive contents of responses to open-ended questions concerning advantages and disadvantages of SNS participation were analyzed using the inductive approach of qualitative content analysis. Contents were organized into codes, concepts, categories, and a storyline based on the grounded theory approach. Social relationships, derived from data of "friends," were analyzed using social network analysis, in which network measures and the extent of interpersonal association were calculated based on the social network theory. Each analysis and integration of results were performed through a concurrent triangulation design of mixed methods strategy. There were 105 participants. Median age was 36 years, and 51% (36/71) were male. There were 37 valid respondents; their number of friends and frequency of accessing the SNS were significantly higher than for invalid/nonrespondents (P = .008 and P = .003). Among respondents, 90% (28/31) were mildly, moderately, or severely depressed. Assessment of the SNS was performed by determining the access frequency of the SNS and the number of friends. Qualitative content analysis indicated that user-selectable peer support could be passive, active, and/or interactive based on anonymity or ease of use, and there was the potential harm of a downward depressive spiral triggered by aggravated psychological burden. Social network analysis revealed that users communicated one-on-one with each other or in small groups (five people or less). A downward depressive spiral was related to friends who were moderately or severely depressed and friends with negative assessment of the SNS. An SNS for people with depressive tendencies provides various opportunities to obtain support that meets users' needs. To avoid a downward depressive spiral, we recommend that participants do not use SNSs when they feel that the SNS is not user-selectable, when they get egocentric comments, when friends have a negative assessment of the SNS, or when they have additional psychological burden.

Two-dimensional bismuth-rich nanosheets through the evaporative thinning of Se-doped Bi2Te3

NASA Astrophysics Data System (ADS)

Hanson, Eve D.; Shi, Fengyuan; Chasapis, Thomas C.; Kanatzidis, Mercouri G.; Dravid, Vinayak P.

2016-02-01

High bulk conductance obscures the behavior of surface states in the prototypical topological insulators Bi2Te3 and Bi2Se3. However, ternary phases of Bi2Te3-ySey with balanced donor and acceptor levels may lead to large bulk resistivity, allowing for the observation of the surface states. Additionally, the contribution of the bulk conductance may be further suppressed by nanostructuring, increasing the surface-to-volume ratio. Herein we report the synthesis of a ternary tetradymite newly confined to two dimensions. Ultra-thin large-area stable nanosheets were fabricated via evaporative thinning of a Bi2Te2.9Se0.1 original phase. Owing to vapor pressure differences, a compositional shift to a final Bi-rich phase is observed. The Se/Te ratio of the nanosheet increases tenfold, due to the higher stability of the Bi-Se bonds. Hexagonal crystal symmetry is maintained despite dramatic changes in thickness and stoichiometry. Given that small variations in stoichiometry of this ternary system can incur large changes in carrier concentration and switch majority carrier type, the large compositional shifts found in this case imply that compositional analysis of similar CVD and PVD grown materials is critical to correctly interpret topological insulator performance. Further, the characterization techniques deployed, including STEM-EDS and ToF-SIMS, serve as a case study in determining such compositional shifts in two-dimensional form.

RADIATION-RESISTANT FIBER OPTIC STRAIN SENSORS FOR SNS TARGET INSTRUMENTATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blokland, Willem; Bryan, Jeff; Riemer, Bernie

2016-01-01

Measurement of stresses and strains in the mercury tar-get vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. This work reports the development of radiation-resistant fiber optic strain sensors for the SNS target in-strumentation.

Transport properties of ultrathin BaFe1.84Co0.16As2 superconducting nanowires

NASA Astrophysics Data System (ADS)

Yuan, Pusheng; Xu, Zhongtang; Li, Chen; Quan, Baogang; Li, Junjie; Gu, Changzhi; Ma, Yanwei

2018-07-01

Superconducting nanowire single-photon detectors (SNSPDs) have an absolute advantage over other types of single-photon detectors, except for the low operating temperature. Therefore, much effort has been devoted to finding high-temperature superconducting materials that are suitable for preparing SNSPDs. Copper-based and MgB2 ultrathin superconducting nanowires have already been reported. However, the transport properties of iron-based ultrathin superconducting nanowires have not been studied. In this work, a 10 nm thick × 200 nm wide × 30 μm long high-quality superconducting nanowire was fabricated from ultrathin BaFe1.84Co0.16As2 films by a lift-off process. The precursor BaFe1.84Co0.16As2 film with a thickness of 10 nm and root-mean-square roughness of 1 nm was grown on CaF2 substrates by pulsed laser deposition. The nanowire shows a high superconducting critical temperature {T}{{c}}{{zero}} = 20 K with a narrow transition width of ΔT = 2.5 K and exhibits a high critical current density J c of 1.8 × 107 A cm-2 at 10 K. These results of ultrathin BaFe1.84Co0.16As2 nanowire will attract interest in electronic applications, including SNSPDs.

Ultrathin MoS2 Nanosheets with Superior Extreme Pressure Property as Boundary Lubricants.

PubMed

Chen, Zhe; Liu, Xiangwen; Liu, Yuhong; Gunsel, Selda; Luo, Jianbin

2015-08-07

In this paper, a new kind of oil-soluble ultrathin MoS2 nanosheets is prepared through a one-pot process. A superior extreme pressure property, which has not been attained with other nano-additives, is discovered when the nanosheets are used as lubricant additives. The as-synthesized MoS2 nanosheet is only a few atomic layers thick and tens of nanometers wide, and it is surface-modified with oleylamine so it can be well dispersed in oil or lubricant without adscititious dispersants or surfactants. By adding 1 wt% ultrathin MoS2 nanosheets, at the temperature of 120 °C, the highest load liquid paraffin can bear is tremendously improved from less than 50 N to more than 2000 N. Based on the tribological tests and analysis of the wear scar, a lubrication mechanism is proposed. It is believed that the good dispersion and the ultrathin shape of the nanosheets ensure that they can enter the contact area of the opposite sliding surfaces and act like a protective film to prevent direct contact and seizure between them. This work enriches the investigation of ultrathin MoS2 and has potential application in the mechanical industry.

Ultrathin MoS2 Nanosheets with Superior Extreme Pressure Property as Boundary Lubricants

NASA Astrophysics Data System (ADS)

Chen, Zhe; Liu, Xiangwen; Liu, Yuhong; Gunsel, Selda; Luo, Jianbin

2015-08-01

In this paper, a new kind of oil-soluble ultrathin MoS2 nanosheets is prepared through a one-pot process. A superior extreme pressure property, which has not been attained with other nano-additives, is discovered when the nanosheets are used as lubricant additives. The as-synthesized MoS2 nanosheet is only a few atomic layers thick and tens of nanometers wide, and it is surface-modified with oleylamine so it can be well dispersed in oil or lubricant without adscititious dispersants or surfactants. By adding 1 wt% ultrathin MoS2 nanosheets, at the temperature of 120 °C, the highest load liquid paraffin can bear is tremendously improved from less than 50 N to more than 2000 N. Based on the tribological tests and analysis of the wear scar, a lubrication mechanism is proposed. It is believed that the good dispersion and the ultrathin shape of the nanosheets ensure that they can enter the contact area of the opposite sliding surfaces and act like a protective film to prevent direct contact and seizure between them. This work enriches the investigation of ultrathin MoS2 and has potential application in the mechanical industry.

Ultrathin MoS2 Nanosheets with Superior Extreme Pressure Property as Boundary Lubricants

PubMed Central

Chen, Zhe; Liu, Xiangwen; Liu, Yuhong; Gunsel, Selda; Luo, Jianbin

2015-01-01

In this paper, a new kind of oil-soluble ultrathin MoS2 nanosheets is prepared through a one-pot process. A superior extreme pressure property, which has not been attained with other nano-additives, is discovered when the nanosheets are used as lubricant additives. The as-synthesized MoS2 nanosheet is only a few atomic layers thick and tens of nanometers wide, and it is surface-modified with oleylamine so it can be well dispersed in oil or lubricant without adscititious dispersants or surfactants. By adding 1 wt% ultrathin MoS2 nanosheets, at the temperature of 120 °C, the highest load liquid paraffin can bear is tremendously improved from less than 50 N to more than 2000 N. Based on the tribological tests and analysis of the wear scar, a lubrication mechanism is proposed. It is believed that the good dispersion and the ultrathin shape of the nanosheets ensure that they can enter the contact area of the opposite sliding surfaces and act like a protective film to prevent direct contact and seizure between them. This work enriches the investigation of ultrathin MoS2 and has potential application in the mechanical industry. PMID:26249536

SnS2 /Sb2 S3 Heterostructures Anchored on Reduced Graphene Oxide Nanosheets with Superior Rate Capability for Sodium-Ion Batteries.

PubMed

Wang, Shijian; Liu, Shuaishuai; Li, Xuemei; Li, Cong; Zang, Rui; Man, Zengming; Wu, Yuhan; Li, Pengxin; Wang, Guoxiu

2018-03-12

Tin disulfide, as a promising high-capacity anode material for sodium-ion batteries, exhibits high theoretical capacity but poor practical electrochemical properties due to its low electrical conductivity. Constructing heterostructures has been considered to be an effective approach to enhance charge transfer and ion-diffusion kinetics. In this work, composites of SnS 2 /Sb 2 S 3 heterostructures with reduced graphene oxide nanosheets were synthesized by a facile one-pot hydrothermal method. When applied as anode material in sodium-ion batteries, the composite showed a high reversible capacity of 642 mA h g -1 at a current density of 0.2 A g -1 and good cyclic stability without capacity loss in 100 cycles. In particular, SnS 2 /Sb 2 S 3 heterostructures exhibited outstanding rate performance with capacities of 593 and 567 mA h g -1 at high current densities of 2 and 4 A g -1 , respectively, which could be ascribed to the dramatically improved Na + diffusion kinetics and electrical conductivity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Perceived stress and life satisfaction: social network service use as a moderator.

PubMed

Niu, Qikun; Liu, Yihao; Sheng, Zitong; He, Yue; Shao, Xiaolin

2011-01-01

Social Network Service (SNS) has become a buzzword in recent media coverage with the development of the second generation of Web-based communities. In China, SNS has played an increasingly important role in its users' daily lives, especially among students. With a sample of 471 college students, we tested the direct relationship between perceived stress and life satisfaction using a regression analysis. Moreover, we found SNS use could buffer the negative effect of perceived stress. This study has practical implications on Internet users' SNS use.

Factors Affecting Intention to Use in Social Networking Sites: An Empirical Study on Thai Society

NASA Astrophysics Data System (ADS)

Jairak, Rath; Sahakhunchai, Napath; Jairak, Kallaya; Praneetpolgrang, Prasong

This research aims to explore the factors that affect the intention to use in Social Networking Sites (SNS). We apply the theory of Technology Acceptance Model (TAM), intrinsic motivation, and trust properties to develop the theoretical framework for SNS users' intention. The results show that the important factors influencing SNS users' intention for general purpose and collaborative learning are task-oriented, pleasure-oriented, and familiarity-based trust. In marketing usage, dispositional trust and pleasure-oriented are two main factors that reflect intention to use in SNS.

Brain anatomy alterations associated with Social Networking Site (SNS) addiction

PubMed Central

He, Qinghua; Turel, Ofir; Bechara, Antoine

2017-01-01

This study relies on knowledge regarding the neuroplasticity of dual-system components that govern addiction and excessive behavior and suggests that alterations in the grey matter volumes, i.e., brain morphology, of specific regions of interest are associated with technology-related addictions. Using voxel based morphometry (VBM) applied to structural Magnetic Resonance Imaging (MRI) scans of twenty social network site (SNS) users with varying degrees of SNS addiction, we show that SNS addiction is associated with a presumably more efficient impulsive brain system, manifested through reduced grey matter volumes in the amygdala bilaterally (but not with structural differences in the Nucleus Accumbens). In this regard, SNS addiction is similar in terms of brain anatomy alterations to other (substance, gambling etc.) addictions. We also show that in contrast to other addictions in which the anterior-/ mid- cingulate cortex is impaired and fails to support the needed inhibition, which manifests through reduced grey matter volumes, this region is presumed to be healthy in our sample and its grey matter volume is positively correlated with one’s level of SNS addiction. These findings portray an anatomical morphology model of SNS addiction and point to brain morphology similarities and differences between technology addictions and substance and gambling addictions. PMID:28332625

Chronic sympathetic activation: consequence and cause of age-associated obesity?

PubMed

Seals, Douglas R; Bell, Christopher

2004-02-01

Primary aging in adult humans is associated with a progressive, tonic activation of the peripheral sympathetic nervous system (SNS). The purpose of this SNS activation and its physiological impact are, however, unknown. We hypothesize that the chronic stimulation of the SNS with aging is driven in part by a progressive accumulation of body fat. This "error" is sensed by the central nervous system via increases in adiposity-sensitive humoral signals (e.g., leptin, insulin) that cross the blood-brain barrier, activate subcortical areas involved in the regulation of energy balance (e.g., ventromedial hypothalamus), and stimulate SNS outflow to peripheral tissues. The SNS activation is intended to increase beta-adrenergic thermogenesis in order to expend excess energy as heat rather than by storage of fat. Recent evidence, however, indicates that these adjustments are not effective in augmenting energy expenditure with aging. Indeed, older sedentary adults demonstrate reduced, not increased, beta-adrenergic stimulation of metabolic rate because of reduced tissue responsiveness, presumably mediated by SNS-induced impairment of beta-adrenergic signaling. As a result, age-associated SNS activation, initiated as a consequence of accumulating adiposity with the intent of preventing further fat storage, ironically, may in time evolve into a potential mechanism contributing to the development of obesity with aging.

Factors associated with online victimisation among Malaysian adolescents who use social networking sites: a cross-sectional study

PubMed Central

Marret, Mary J; Choo, Wan Yuen

2017-01-01

Objective To determine the prevalence of online interpersonal victimisation and its association with patterns of social networking site (SNS) use, offline victimisation, offline perpetration and parental conflict among Malaysian adolescents using SNS. Methods A cross-sectional study of students from randomly selected public secondary schools in the state of Negeri Sembilan was conducted using an anonymous self-administered questionnaire. The questionnaire examined patterns of SNS use and included measures of online victimisation, online perpetration, offline victimisation and parental conflict. A response rate of 91% from a total of 1634 yielded a sample of 1487 students between 15 years and 16 years of age. Results Ninety-two per cent of respondents had used at least one SNS. More than half of SNS users (52.2%) reported experiences of online victimisation over the past 12 months. Boys were significantly more likely to experience online harassment compared with girls (52.2% vs 43.3%, p<0.001). There were no significant gender differences in experiences of unwanted sexual solicitation. Adolescents who engaged in perpetration behaviours online had almost six times higher odds of reporting frequent online victimisation compared with online behaviours involving personal disclosure. There was a significant dose-response relationship between engagement in multiple types of online behaviour and the risk of frequent online victimisation. Both online and offline perpetrations were associated with an increased risk of victimisation. Those who were victimised offline or experienced parental conflict were twice as likely to report online victimisation. Conclusion Interventions to prevent online electronic aggression should target perpetration behaviour both online and offline. Youth should be equipped with skills in communication and decision-making in relationships that can be applied across a spectrum of contexts both online and offline. PMID:28667209

Surface oxidation of tin chalcogenide nanocrystals revealed by 119Sn-Mössbauer spectroscopy.

PubMed

de Kergommeaux, Antoine; Faure-Vincent, Jérôme; Pron, Adam; de Bettignies, Rémi; Malaman, Bernard; Reiss, Peter

2012-07-18

Narrow band gap tin(II) chalcogenide (SnS, SnSe, SnTe) nanocrystals are of high interest for optoelectronic applications such as thin film solar cells or photodetectors. However, charge transfer and charge transport processes strongly depend on nanocrystals' surface quality. Using (119)Sn-Mössbauer spectroscopy, which is the most sensitive tool for probing the Sn oxidation state, we show that SnS nanocrystals exhibit a Sn((IV))/Sn((II)) ratio of around 20:80 before and 40:60 after five minutes exposure to air. Regardless of the tin or sulfur precursors used, similar results are obtained using six different synthesis protocols. The Sn((IV)) content before air exposure arises from surface related SnS(2) and Sn(2)S(3) species as well as from surface Sn atoms bound to oleic acid ligands. The increase of the Sn((IV)) content upon air exposure results from surface oxidation. Full oxidation of the SnS nanocrystals without size change is achieved by annealing at 500 °C in air. With the goal to prevent surface oxidation, SnS nanocrystals are capped with a cadmium-phosphonate complex. A broad photoluminescence signal centered at 600 nm indicates successful capping, which however does not reduce the air sensitivity. Finally we demonstrate that SnSe nanocrystals exhibit a very similar behavior with a Sn((IV))/Sn((II)) ratio of 43:57 after air exposure. In the case of SnTe nanocrystals, the ratio of 55:45 is evidence of a more pronounced tendency for oxidation. These results demonstrate that prior to their use in optoelectronics further surface engineering of tin chalcogenide nanocrystals is required, which otherwise have to be stored and processed under inert atmosphere.

Impact of Sodium Contamination in Tin Sulfide Thin-Film Solar Cells

DOE PAGES

Steinmann, Vera; Brandt, Riley E.; Chakraborty, Rupak; ...

2016-02-12

Empirical observations show that sodium(Na) is a benign contaminant in some thin-filmsolar cells. Here, we intentionally contaminate thermally evaporated tin sulfide (SnS)thin-films with sodium and measure the SnS absorber properties and solar cellcharacteristics. The carrier concentration increases from 2 × 10 16 cm -3 to 4.3 × 10 17 cm -3 in Na-doped SnSthin-films, when using a 13 nm NaCl seed layer, which is detrimental for SnS photovoltaic applications but could make Na-doped SnS an attractive candidate in thermoelectrics. We observed trends in carrier concentration and found that it is in good agreement with density functional theory calculations, which predictmore » an acceptor-type NaSn defect with low formation energy.« less

H- ion source developments at the SNSa)

NASA Astrophysics Data System (ADS)

Welton, R. F.; Stockli, M. P.; Murray, S. N.; Pennisi, T. R.; Han, B.; Kang, Y.; Goulding, R. H.; Crisp, D. W.; Sparks, D. O.; Luciano, N. P.; Carmichael, J. R.; Carr, J.

2008-02-01

The U.S. Spallation Neutron Source (SNS) will require substantially higher average and pulse H- beam currents than can be produced from conventional ion sources such as the base line SNS source. H- currents of 40-50mA (SNS operations) and 70-100mA (power upgrade project) with a rms emittance of 0.20-0.35πmmmrad and a ˜7% duty factor will be needed. We are therefore investigating several advanced ion source concepts based on rf plasma excitation. First, the performance characteristics of an external antenna source based on an Al2O3 plasma chamber combined with an external multicusp magnetic configuration, an elemental Cs system, and plasma gun will be discussed. Second, the first plasma measurements of a helicon-driven H- ion source will also be presented.

Electronic and magnetic properties of SnS2 monolayer doped with 4d transition metals

NASA Astrophysics Data System (ADS)

Xiao, Wen-Zhi; Xiao, Gang; Rong, Qing-Yan; Chen, Qiao; Wang, Ling-Ling

2017-09-01

We investigate the electronic structures and magnetic properties of SnS2 monolayers substitutionally doped with 4-d transition-metal through systematic first principles calculations. The doped complexes exhibit interesting electronic and magnetic behaviors, depending on the interplay between crystal field splitting, Hund's rule, and 4d levels. The system doped with Y is nonmagnetic metal. Both the Zr- and Pd-doped systems remain nonmagnetic semiconductors. Doping results in half-metallic states for Nb-, Ru-, Rh-, Ag, and Cd doped cases, and magnetic semiconductors for systems with Mo and Tc dopants. In particular, the Nb- and Mo-doped systems display long-ranged ferromagnetic ordering with Curie temperature above room temperature, which are primarily attributable to the double-exchange mechanism, and the p-d/p-p hybridizations, respectively. Moreover, The Mo-doped system has excellent energetic stability and flexible mechanical stability, and also possesses remarkable dynamic and thermal (500 K) stability. Our studies demonstrate that Nb- and Mo-doped SnS2 monolayers are promising candidates for preparing 2D diluted magnetic semiconductors, and hence will be a helpful clue for experimentalists.

3D Porous Nanoarchitectures Derived from SnS/S-Doped Graphene Hybrid Nanosheets for Flexible All-Solid-State Supercapacitors.

PubMed

Liu, Chunyan; Zhao, Shulin; Lu, Yanan; Chang, Yingxue; Xu, Dongdong; Wang, Qi; Dai, Zhihui; Bao, Jianchun; Han, Min

2017-03-01

3D porous nanoarchitectures derived from SnS/S-doped graphene hybrid nanosheets are successfully prepared by controllable thermal conversion of oleylamine-capped mixed-phase SnS 2 -SnS nanodisks precursors, and employed as electroactive material to fabricate flexible, symmetric, all-solid-state supercapacitors. The fabricated solid devices exhibit very high areal specific capacitance (2.98 mF cm -2 ), good cycling stability (99% for 10 000 cycles), excellent flexibility, and desirable mechanical stability. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Manipulation of Spin-Torque Generation Using Ultrathin Au

NASA Astrophysics Data System (ADS)

An, Hongyu; Haku, Satoshi; Kanno, Yusuke; Nakayama, Hiroyasu; Maki, Hideyuki; Shi, Ji; Ando, Kazuya

2018-06-01

The generation and the manipulation of current-induced spin-orbit torques are of essential interest in spintronics. However, in spite of the vital progress in spin orbitronics, electric control of the spin-torque generation still remains elusive and challenging. We report on electric control of the spin-torque generation using ionic-liquid gating of ultrathin Au. We show that by simply depositing a SiO2 capping layer on an ultrathin-Au /Ni81Fe19 bilayer, the spin-torque generation efficiency is drastically enhanced by a maximum of 7 times. This enhancement is verified to be originated from the rough ultrathin-Au /Ni81Fe19 interface induced by the SiO2 deposition, which results in the enhancement of the interface spin-orbit scattering. We further show that the spin-torque generation efficiency from the ultrathin Au film can be reversibly manipulated by a factor of 2 using the ionic gating with an external electric field within a small range of 1 V. These results pave a way towards the efficient control of the spin-torque generation in spintronic applications.

Single crystalline silicene consist of various superstructures using a flexible ultrathin Ag(111) template on Si(111)

NASA Astrophysics Data System (ADS)

Hsu, Hung-Chang; Lu, Yi-Hung; Su, Tai-Lung; Lin, Wen-Chin; Fu, Tsu-Yi

2018-07-01

Using scanning tunneling microscopy, we studied the formation of silicene on an ultrathin Ag(111) film with a thickness of 6–12 monolayers, which was prepared on a Si(111) substrate. A low-energy electron diffraction pattern with an oval spot indicated that the ultrathin Ag(111) film is more disordered than the single-crystal Ag(111). After Si epitaxy growth, we still measured the classical 4 × 4, √13 × √13, and 2√3 × 2√3 silicene superstructures, which are the same as the silicene superstructure on single-crystal Ag(111). Growing silicene on a single-crystal Ag(111) bulk usually results in the formation of a defect boundary due to the inconsistent orientation of various superstructures. By comparing the angles and boundary conditions between various silicene superstructures on the ultrathin film and single-crystal Ag(111), we discovered that a consistent orientation of various superstructures without obvious boundary defects formed on the ultrathin Ag(111) film. The results indicated single crystalline silicene formation, which was attributed to the domain rotation and lateral shift of the disordered ultrathin Ag(111) film.

Communication inequalities and public health implications of adult social networking site use in the United States.

PubMed

Kontos, Emily Z; Emmons, Karen M; Puleo, Elaine; Viswanath, K

2010-01-01

Social media, and specifically social networking sites (SNSs), are emerging as an important platform for communication and health information exchange. Yet, despite the increase in popularity and use, only a limited number of empirical studies document which segments of the adult population are and are not using social networking sites and with what, if any, affect on health. The purpose of this study is to identify potential communication inequalities in social networking site use among a representative sample of U.S. adults and to examine the association between SNS use and psychological well-being. We analyzed data from the National Cancer Institute's 2007 Health Information National Trends Survey (HINTS). Thirty-five percent of online adults reported SNS use within the past 12 months, and there were no significant differences in SNS use by race/ethnicity or socioeconomic position. Younger age (p = .00) was the most significant predictor of SNS use, while being married (p = .02) and having a history of cancer (p = .02) were associated with a decreased odds of SNS use. SNS use was significantly associated with a 0.80 (p = .00) increment in psychological distress score after controlling for other factors. The absence of inequalities in adult SNS use across race/ethnicity and class offers some support for the continued use of social media to promote public health efforts; however, issues such as the persisting digital divide and potential deleterious effects of SNS use on psychological well-being need to be addressed.

GH replacement therapy and second neoplasms in adult survivors of childhood cancer: a retrospective study from a single institution.

PubMed

Brignardello, E; Felicetti, F; Castiglione, A; Fortunati, N; Matarazzo, P; Biasin, E; Sacerdote, C; Ricardi, U; Fagioli, F; Corrias, A; Arvat, E

2015-02-01

Growth hormone deficiency (GHD) is the most common endocrine late effect observed in childhood cancer survivors (CCS) previously submitted to cranial irradiation. Radiation therapy can also increase the risk of second neoplasms (SNs). Since in previous studies GH replacement therapy was associated with increased incidence of neoplasia, we explored the association between SNs and GH replacement therapy in a cohort of CCS with GHD. Within the clinical cohort of CCS referred to the Transition Unit for Childhood Cancer Survivors of Turin between November 2001 and December 2012, we considered all patients who developed GHD as a consequence of cancer therapies. GHD was always diagnosed in childhood. To evaluate the quality of data, our cohort was linked to the Childhood Cancer Registry of Piedmont. GHD was diagnosed in 49 out of 310 CCS included in our clinical cohort. At least one SN was diagnosed in 14 patients, meningioma and basal cell carcinoma being the most common SNs. The cumulative incidence of SNs was similar in GH-treated and -untreated patients (8 SNs out of 26 GH-treated and 6 out of 23 GH-untreated patients; p = 0.331). Age, sex and paediatric cancer type had no impact on SNs development. In our CCS, GH replacement therapy does not seem to increase the risk of SNs. Anyway, independently from replacement therapy, in these patients we observed an elevated risk of SNs, possibly related to previous radiation therapy, which suggests the need of a close long-term follow-up.

Communication Inequalities and Public Health Implications of Adult Social Networking Site Use in the United States

PubMed Central

Kontos, Emily Z.; Emmons, Karen M.; Puleo, Elaine; Viswanath, K.

2011-01-01

Background Social media, and specifically social networking sites (SNS), are emerging as an important platform for communication and health information exchange. Yet, despite the increase in popularity and use, only a limited number of empirical studies document which segments of the adult population are and are not using social networking sites and with what, if any, affect on health. Methods The purpose of this study is to identify potential communication inequalities in social networking site use among a representative sample of US adults and to examine the association between SNS-use and psychological well-being. We analyzed data from the National Cancer Institute’s 2007 Health Information National Trends Survey (HINTS). Results Thirty-five percent of online adults reported SNS-use within the past 12 months, and; there were no significant differences in SNS-use by race/ethnicity or socio-economic position. Younger age (p=.00) was the most significant predictor of SNS-use while being married (p=.02) and having a history of cancer (p=.02) were associated with a decreased odds of SNS-use. Social networking site use was significantly associated with a 0.80 (p=.00) increment in psychological distress score after controlling for other factors. Conclusion The absence of inequalities in adult SNS-use across race/ethnicity and class offers some support for the continued use of social media to promote public health efforts; however, issues such as the persisting Digital Divide and potential deleterious effects of SNS-use on psychological well-being need to be addressed. PMID:21154095

Learning through Social Networking Sites--The Critical Role of the Teacher

ERIC Educational Resources Information Center

Callaghan, Noelene; Bower, Matt

2012-01-01

This comparative case study examined factors affecting behaviour and learning in social networking sites (SNS). The behaviour and learning of two classes completing identical SNS based modules of work was observed and compared. All student contributions to the SNS were analysed, with the cognitive process dimension of the Revised Bloom's Taxonomy…

Negative consequences from heavy social networking in adolescents: The mediating role of fear of missing out.

PubMed

Oberst, Ursula; Wegmann, Elisa; Stodt, Benjamin; Brand, Matthias; Chamarro, Andrés

2017-02-01

Social networking sites (SNS) are especially attractive for adolescents, but it has also been shown that these users can suffer from negative psychological consequences when using these sites excessively. We analyze the role of fear of missing out (FOMO) and intensity of SNS use for explaining the link between psychopathological symptoms and negative consequences of SNS use via mobile devices. In an online survey, 1468 Spanish-speaking Latin-American social media users between 16 and 18 years old completed the Hospital Anxiety and Depression Scale (HADS), the Social Networking Intensity scale (SNI), the FOMO scale (FOMOs), and a questionnaire on negative consequences of using SNS via mobile device (CERM). Using structural equation modeling, it was found that both FOMO and SNI mediate the link between psychopathology and CERM, but by different mechanisms. Additionally, for girls, feeling depressed seems to trigger higher SNS involvement. For boys, anxiety triggers higher SNS involvement. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Correlates to sleepiness on night shift among male workers engaged in three-shift work in a chemical plant: its association with sleep practice and job stress.

PubMed

Kageyama, Takayuki; Kobayashi, Toshio; Abe-Gotoh, Ayano

2011-01-01

The purpose of this study was to examine the correlation of sleepiness during night shift (SNS) in male shiftworkers with nonpharmacological self-management (nPSM) practices to facilitate good day sleep, and also with job stress. Sleepiness on the job and possible correlates to SNS among 157 male shiftworkers in a rotating three-shift schedule at a chemical plant were cross-sectionally investigated using a self-administered questionnaire. Multivariate analyses revealed that SNS was positively associated with drinking alcoholic beverages before day sleep, but inversely associated with subjective health status, being of the evening type, abstaining from caffeine before day sleep, having a bath before day sleep, job control, reward from work, feeling suited to the job, and support from colleagues. SNS correlated with certain nPSM practices and also with possible modifiers of job stress. These findings provide clues to developing countermeasures against SNS among shiftworkers. The effects of nPSM practices and job stress management on their day sleep and SNS should be examined in detail.

Sweat pore reactivity as a surrogate measure of sympathetic nervous system activity in trauma-exposed individuals with and without posttraumatic stress disorder.

PubMed

Familoni, Babajide O; Gregor, Kristin L; Dodson, Thomas S; Krzywicki, Alan T; Lowery, Bobby N; Orr, Scott P; Suvak, Michael K; Rasmusson, Ann M

2016-09-01

Stress analysis by FLIR (forward-looking infrared) evaluation (SAFE) has been demonstrated to monitor sweat pore activation (SPA) as a novel surrogate measure of sympathetic nervous system (SNS) activity in a normal population. SNS responses to a series of 15 1-s, 82 dB, white noise bursts were measured by skin conductance (SC) and SAFE monitoring of SPA on the fingers (FiP) and face (FaP) in 10 participants with posttraumatic stress disorder (PTSD) and 16 trauma-exposed participants without PTSD (Mage  = 48.92 ± 12.00 years; 26.9% female). Within participants, SC and FiP responses across trials were strongly correlated (r = .92, p < .001). Correlations between SC and FaP (r = .76, p = .001) and between FiP and FaP (r = .47, p = .005) were smaller. The habituation of SNS responses across the 15 trials was substantial (SC: d = -2.97; FiP: d = -2.34; FaP: d = -1.02). There was a strong correlation between habituation effects for SC and FiP (r = .76, p < .001), but not for SC and FaP (r = .15, p = .45) or FiP and FaP (r = .29, p = .16). Participants with PTSD showed larger SNS responses to the first loud noise than those without PTSD. PTSD reexperiencing symptoms assessed by the PTSD Checklist on the day of testing were associated with the SNS responses to the first loud noise measured by SC (d = 1.19) and FiP (d = .99), but not FaP (d = .10). This study confirms convergence of SAFE and SC as valid measures of SNS activity. SAFE FiP and SC responses were highly predictive of self-rated PTSD reexperiencing symptoms. SAFE may offer an attractive alternative for applications in PTSD and similar populations. © 2016 Society for Psychophysiological Research. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

A correlation study of social network usage among health care students.

PubMed

Suit, Louise; Winkler, Patricia; Campbell, Linda; Pennington, Karen; Szutenbach, Mary Pat; Haight, Robert; Roybal, Deborah; McCollum, Marianne

2015-04-01

Due to anecdotal concerns about adequacy of health professions students' communication skills, health professions faculty at a private university formed an interprofessional research team. The study was designed to explore whether the use of social networking services (SNS) influenced health care students' written and oral communication skills. One hundred thirty-two students participated in the study. Communication skills were assessed by using assignments from a health care ethics course required of all students. Use of SNS was measured with an information technology questionnaire. Contrary to expected findings, this exploratory correlation study found no meaningful relationship between the frequency of SNS usage and oral and written communication skills in health professions students. Future studies of SNS would benefit from a younger and more homogeneous study population to assess the use of SNS for learning versus leisure. Copyright 2015, SLACK Incorporated.

Development of SnS (FTO/CdS/SnS) thin films by nebulizer spray pyrolysis (NSP) for solar cell applications

NASA Astrophysics Data System (ADS)

Arulanantham, A. M. S.; Valanarasu, S.; Jeyadheepan, K.; Ganesh, V.; Shkir, Mohd

2018-01-01

Herein we report a well-organized analysis on various key-properties of SnS thin films for solar cell fabricated by nebulizer spray pyrolysis technique. X-ray diffraction study reveals the polycrystalline nature of deposited films with orthorhombic crystal structure. The crystallite size was calculated and observed to be in the range of 8-28 nm with increasing molarity of precursor solution. The stoichiometry composition of SnS was confirmed by EDX study. SEM/AFM studies divulge the well-covered deposited surface with spherical grains and the size of grains is increasing with concentration and so the roughness. A remarkable decrease in band gap from 2.6 eV to 1.6 eV was noticed by raising the molar concentration from 0.025 M up to 0.075 M. A single strong emission peak at about 825 nm is observed in PL spectra with enhanced intensity which may be attributed to near band edge emission. From the Hall effect measurement, it was found that the SnS thin film exhibits p-type conductivity. The calculated values of resistivity and carrier concentration are 0.729 Ω cm and 3.67 × 1018/cm3 respectively. Furthermore, to study the photovoltaic properties of SnS thin films a heterojunction solar cell, FTO/n-CdS/p-SnS was produced and the conversion efficiency was recorded about 0.01%.

Incommensurate growth of Co thin film on close-packed Ag(111) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barman, Sukanta, E-mail: sukanta.ac@gmail.com; Menon, Krishna Kumar S. R., E-mail: krishna.menon@saha.ac.in

2016-05-06

Growth of ultrathin Co layers on close-packed Ag(111)were investigated by means of Low Energy Electron Diffraction (LEED), X-ray Photoelectron Spectroscopy (XPS) and Angle-resolved Photoemission Spectroscopy(ARPES) techniques. The close-packed hexagonal face of Co(0001), exhibits a lattice misfit about 13% with Ag(111) surface which manipulates the growth to be incommensurate up to a certain thickness. The strain field causes aperiodic height undulation in the sub-angstrom regime of the film which was confirmed by p(1 × 1) LEED pattern along with a 6-fold moiré reconstruction pattern in the lower film thickness (up to ∼2ML). The evolution of the LEED pattern was studied withmore » increasing film coverage. Lattice strain was measured with respect to the relative positions of these double spots as a functionof film thickness. Almost a constant strain (∼13%) in the full range of film thickness explains the moiré pattern formation in order to stabilize the incommensurate growth. For higher film coverages, an epitaxial well-ordered commensurate growth was observed. Core level and valance band electronic structures of these films were studied by XPS and ARPES techniques.« less

One-step fabrication of large-area ultrathin MoS2 nanofilms with high catalytic activity for photovoltaic devices.

PubMed

Liang, Jia; Li, Jia; Zhu, Hongfei; Han, Yuxiang; Wang, Yanrong; Wang, Caixing; Jin, Zhong; Zhang, Gengmin; Liu, Jie

2016-09-21

Here we report a facile one-step solution-phase process to directly grow ultrathin MoS2 nanofilms on a transparent conductive glass as a novel high-performance counter electrode for dye-sensitized solar cells. After an appropriate reaction time, the entire surface of the conductive glass substrate was uniformly covered by ultrathin MoS2 nanofilms with a thickness of only several stacked layers. Electrochemical impedance spectroscopy and cyclic voltammetry reveal that the MoS2 nanofilms possess excellent catalytic activity towards tri-iodide reduction. When used in dye-sensitized solar cells, the MoS2 nanofilms show an impressive energy conversion efficiency of 8.3%, which is higher than that of a Pt-based electrode and very promising to be a desirable alternative counter electrode. Considering their ultrathin thickness, superior catalytic activity, simple preparation process and low cost, the as-prepared MoS2 nanofilms with high photovoltaic performance are expected to be widely employed in dye-sensitized solar cells.

Multiple damage identification on a wind turbine blade using a structural neural system

NASA Astrophysics Data System (ADS)

Kirikera, Goutham R.; Schulz, Mark J.; Sundaresan, Mannur J.

2007-04-01

A large number of sensors are required to perform real-time structural health monitoring (SHM) to detect acoustic emissions (AE) produced by damage growth on large complicated structures. This requires a large number of high sampling rate data acquisition channels to analyze high frequency signals. To overcome the cost and complexity of having such a large data acquisition system, a structural neural system (SNS) was developed. The SNS reduces the required number of data acquisition channels and predicts the location of damage within a sensor grid. The sensor grid uses interconnected sensor nodes to form continuous sensors. The combination of continuous sensors and the biomimetic parallel processing of the SNS tremendously reduce the complexity of SHM. A wave simulation algorithm (WSA) was developed to understand the flexural wave propagation in composite structures and to utilize the code for developing the SNS. Simulation of AE responses in a plate and comparison with experimental results are shown in the paper. The SNS was recently tested by a team of researchers from University of Cincinnati and North Carolina A&T State University during a quasi-static proof test of a 9 meter long wind turbine blade at the National Renewable Energy Laboratory (NREL) test facility in Golden, Colorado. Twelve piezoelectric sensor nodes were used to form four continuous sensors to monitor the condition of the blade during the test. The four continuous sensors are used as inputs to the SNS. There are only two analog output channels of the SNS, and these signals are digitized and analyzed in a computer to detect damage. In the test of the wind turbine blade, multiple damages were identified and later verified by sectioning of the blade. The results of damage identification using the SNS during this proof test will be shown in this paper. Overall, the SNS is very sensitive and can detect damage on complex structures with ribs, joints, and different materials, and the system relatively inexpensive and simple to implement on large structures.

Spin filter effect of hBN/Co detector electrodes in a 3D topological insulator spin valve

NASA Astrophysics Data System (ADS)

Vaklinova, Kristina; Polyudov, Katharina; Burghard, Marko; Kern, Klaus

2018-03-01

Topological insulators emerge as promising components of spintronic devices, in particular for applications where all-electrical spin control is essential. While the capability of these materials to generate spin-polarized currents is well established, only very little is known about the spin injection/extraction into/out of them. Here, we explore the switching behavior of lateral spin valves comprising the 3D topological insulator Bi2Te2Se as channel, which is separated from ferromagnetic Cobalt detector contacts by an ultrathin hexagonal boron nitride (hBN) tunnel barrier. The corresponding contact resistance displays a notable variation, which is correlated with a change of the switching characteristics of the spin valve. For contact resistances below ~5 kΩ, the hysteresis in the switching curve reverses upon reversing the applied current, as expected for spin-polarized currents carried by the helical surface states. By contrast, for higher contact resistances an opposite polarity of the hysteresis loop is observed, which is independent of the current direction, a behavior signifying negative spin detection efficiency of the multilayer hBN/Co contacts combined with bias-induced spin signal inversion. Our findings suggest the possibility to tune the spin exchange across the interface between a ferromagnetic metal and a topological insulator through the number of intervening hBN layers.

Synthesis of bilayer MoS{sub 2} nanosheets by a facile hydrothermal method and their methyl orange adsorption capacity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Lijuan; Xu, Haiyan; Zhang, Dingke

2014-07-01

Highlights: • Hexagonal phase of MoS{sub 2} nanosheets was synthesized by a facile hydrothermal method. • FE-SEM and TEM images show the sheets-like morphology of MoS{sub 2}. • Bilayer MoS{sub 2} can be grown under the optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. • The MoS{sub 2} nanosheets possess high methyl orange adsorption capacity due to the large surface area. - Abstract: Molybdenum disulfide (MoS{sub 2}) nanosheets have received significant attention recently due to the potential applications for exciting physics and technology. Here we show that MoS{sub 2} nanosheets can be prepared by amore » facile hydrothermal method. The study of the properties of the MoS{sub 2} nanosheets prepared at different conditions suggests that the mole ratio of precursors and hydrothermal time significantly influences the purity, crystalline quality and thermal stability of MoS{sub 2}. X-ray diffraction, Raman spectra and transmission electron microscopy results indicate that bilayer MoS{sub 2} can be grown under an optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. Moreover, such ultrathin nanosheets exhibit a prominent photoluminescence and possess high methyl orange adsorption capacity due to the large surface area, which can be potentially used in photodevice and photochemical catalyst.« less

Enhanced light trapping and high charge transmission capacities of novel structures for efficient photoelectrochemical water splitting.

PubMed

Mu, Jianglong; Miao, Hui; Liu, Enzhou; Feng, Juan; Teng, Feng; Zhang, Dekai; Kou, Yumeng; Jin, Yanping; Fan, Jun; Hu, Xiaoyun

2018-06-13

Excellent PEC efficiency, good reusability and the super stability of trap-like SnS2/TiO2 nanotube arrays (NTs)-based photoanodes are reported. Specifically, the SnS2/TiO2-180 °C (ST-180) photoanode exhibited the highest photocurrent density (1.05 mA cm-2) and an optimal η (0.73%) at 0.5 V (vs. SCE) under simulated light irradiation (AM 1.5G), which are 4.6 and 3.8 times higher than those of pure TiO2 NTs (0.23 mA cm-2 and 0.19%). The IPCE values of ST-180 can reach 21.5% (365 nm) and 13.8% (420 nm), which are much higher than those of pure TiO2 NTs (10.6% at 365 nm and 0.8% at 420 nm). The APCE values of the pure TiO2 NTs photoelectrode are 12.8% (365 nm) and 1.1% (420 nm), while the ST-180 values are 22.3% and 14.2%, respectively. Furthermore, the generation rates of H2 and O2 for the ST-180 photoanode are 47.2 and 23.1 μmol cm-2 h-1 at 0.5 V under AM 1.5G, corresponding to faradaic efficiencies of around 80.1% and 78.3%, respectively. In short, the high-efficiency PEC water splitting performance of this SnS2/TiO2 photoanode results from the enhanced light harvesting ability of the trap-like SnS2 structure, accelerated carrier transportation properties of TiO2 NTs, and effective carrier separation of the type-II heterojunction structure. This work may offer a combinatorial strategy for the preparation of heterojunction structures with high PEC performance and can be a model structure for similar photoanode materials.

Thermoelectric properties of SnSe1-xSx(0

NASA Astrophysics Data System (ADS)

Nguyen, Thi Minh Hai; Duong, Anh Tuan; Duvjir, Ganbat; Trinh, Thi Ly; Nguyen, Van Quang; Kim, Jungdae; Cho, Sunglae

Tin selenide (SnSe), a p-type semiconductor, has attracted many attention due to its excellent thermoelectric efficiency, i.e., ZT = 2.6 along the b-axis of its high temperature phase. This issue has renewed interests in thermoelectric properties of the materials which adopted the same layered structure as SnSe, such as SnS, GeS, and GeSe. Among these compounds, tin (II) sulfide (SnS) is exceptionally attractive because of its natural abundance and low toxicity. However, the experimental results show that SnS has possessed a small value of the figure of merit. To optimize the thermoelectric performance of SnS, making solid solution is a potential way. That is our motivation for the investigation of SnSe1-xSx single crystals' thermoelectric properties. In this study, SnSe1-xSx (0

Novel high pressure hexagonal OsB2 by mechanochemistry

NASA Astrophysics Data System (ADS)

Xie, Zhilin; Graule, Moritz; Orlovskaya, Nina; Andrew Payzant, E.; Cullen, David A.; Blair, Richard G.

2014-07-01

Hexagonal OsB2, a theoretically predicted high-pressure phase, has been synthesized for the first time by a mechanochemical method, i.e., high energy ball milling. X-ray diffraction indicated that formation of hexagonal OsB2 begins after 2.5 h of milling, and the reaction reaches equilibrium after 18 h of milling. Rietveld refinement of the powder data indicated that hexagonal OsB2 crystallizes in the P63/mmc space group (No. 194) with lattice parameters of a=2.916 Å and c=7.376 Å. Transmission electron microscopy confirmed the appearance of the hexagonal OsB2 phase after high energy ball milling. in situ X-ray diffraction experiments showed that the phase is stable from -225 °C to 1050 °C. The hexagonal OsB2 powder was annealed at 1050 °C for 6 days in vacuo to improve crystallinity and remove strain induced during the mechanochemical synthesis. The structure partially converted to the orthorhombic phase (20 wt%) after fast current assisted sintering of hexagonal OsB2 at 1500 °C for 5 min. Mechanochemical approaches to the synthesis of hard boride materials allow new phases to be produced that cannot be prepared using conventional methods.

Social Media in Health Professional Education: A Student Perspective on User Levels and Prospective Applications

ERIC Educational Resources Information Center

Maloney, Stephen; Moss, Alan; Ilic, Dragan

2014-01-01

Social Networking Sites (SNS) have seen exponential growth in recent years. The high utilisation of SNS by tertiary students makes them an attractive tool for educational institutions. This study aims to identify health professional students' use and behaviours with SNS, including students' perspectives on potential applications within…

Few-layered CoHPO4 · 3H2O ultrathin nanosheets for high performance of electrode materials for supercapacitors.

PubMed

Pang, Huan; Wang, Shaomei; Shao, Weifang; Zhao, Shanshan; Yan, Bo; Li, Xinran; Li, Sujuan; Chen, Jing; Du, Weimin

2013-07-07

Ultrathin cobalt phosphate (CoHPO4 · 3H2O) nanosheets are successfully synthesized by a one pot hydrothermal method. Novel CoHPO4 · 3H2O ultrathin nanosheets are assembled for constructing the electrodes of supercapacitors. Benefiting from the nanostructures, the as-prepared electrode shows a specific capacitance of 413 F g(-1), and no obvious decay even after 3000 charge-discharge cycles. Such a quasi-two-dimensional material is a new kind of supercapacitor electrode material with high performance.

Characterization of the Shielded Neutron Source at Triangle Universities Nuclear Laboratory

NASA Astrophysics Data System (ADS)

Hobson, Chad; Finch, Sean; Howell, Calvin; Malone, Ron; Tornow, Wernew

2016-09-01

In 2015, Triangle Universities Nuclear Laboratory rebuilt its shielded neutron source (SNS) with the goal of improving neutron beam collimation and reducing neutron and gamma-ray backgrounds. Neutrons are produced via the 2H(d,n)3He reaction and then collimated by heavy shielding to form a beam. The SNS has the ability to produce both a rectangular and circular neutron beam through use of two collimators with different beam apertures. Our work characterized both the neutron beam profiles as well as the neutron and gamma-ray backgrounds at various locations around the SNS. This characterization was performed to provide researchers who use the SNS with beam parameters necessary to plan and conduct an experiment. Vertical and horizontal beam profiles were measured at two different distances from the neutron production cell by scanning a small plastic scintillator across the face of the beam at various energies for each collimator. Background neutron and gamma-ray intensities were measured using time-of-flight techniques at 10 MeV and 16 MeV with the rectangular collimator. We present results on the position and size of neutron beam as well as on the structure and magnitude of the backgrounds.

Ion Source Development at the SNS

NASA Astrophysics Data System (ADS)

Welton, R. F.; Stockli, M. P.; Murray, S. N.; Carr, J.; Carmichael, J.; Goulding, R. H.; Baity, F. W.

2007-08-01

The US Spallation Neutron Source (SNS) has recently begun producing neutrons and is currently on track to becoming a world-leading facility for material science based on neutron scattering. The facility is comprised of an H- ion source, a linear accelerator, an accumulator ring, a liquid-Hg target and a suite of neutron scattering instruments. Over the next several years the average H- current from the ion source will be increased in order to meet the baseline facility requirement of providing 1.4 MW of beam-power to the target and the SNS power upgrade power requirement of 2+ MW on target. Meeting the latter goal will require H- currents of 70-100 mA with an RMS emittance of 0.20-0.35 π mm mrad and a ˜7% duty-factor. To date, the RF-driven-multicusp SNS ion source has only been able to demonstrate sustained operation at 33 mA of beam current at a ˜7% duty-factor. This report details our efforts to develop variations of the current ion source which can meet these requirements. Designs and experimental results are presented for helicon plasma drivers, high-power external antennas, glow-discharge plasma guns and advanced Cs systems.

320-nm Flexible Solution-Processed 2,7-dioctyl[1] benzothieno[3,2-b]benzothiophene Transistors

PubMed Central

Ren, Hang; Tang, Qingxin; Tong, Yanhong; Liu, Yichun

2017-01-01

Flexible organic thin-film transistors (OTFTs) have received extensive attention due to their outstanding advantages such as light weight, low cost, flexibility, large-area fabrication, and compatibility with solution-processed techniques. However, compared with a rigid substrate, it still remains a challenge to obtain good device performance by directly depositing solution-processed organic semiconductors onto an ultrathin plastic substrate. In this work, ultrathin flexible OTFTs are successfully fabricated based on spin-coated 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) films. The resulting device thickness is only ~320 nm, so the device has the ability to adhere well to a three-dimension curved surface. The ultrathin C8-BTBT OTFTs exhibit a mobility as high as 4.36 cm2 V−1 s−1 and an on/off current ratio of over 106. These results indicate the substantial promise of our ultrathin flexible C8-BTBT OTFTs for next-generation flexible and conformal electronic devices. PMID:28792438

Synthesis of Sub-2 nm Iron-Doped NiSe2 Nanowires and Their Surface-Confined Oxidation for Oxygen Evolution Catalysis.

PubMed

Gu, Chao; Hu, Shaojin; Zheng, Xusheng; Gao, Min-Rui; Zheng, Ya-Rong; Shi, Lei; Gao, Qiang; Zheng, Xiao; Chu, Wangsheng; Yao, Hong-Bin; Zhu, Junfa; Yu, Shu-Hong

2018-04-03

Ultrathin nanostructures are attractive for diverse applications owing to their unique properties compared to their bulk materials. Transition-metal chalcogenides are promising electrocatalysts, yet it remains difficult to make ultrathin structures (sub-2 nm), and the realization of their chemical doping is even more challenging. Herein we describe a soft-template mediated colloidal synthesis of Fe-doped NiSe 2 ultrathin nanowires (UNWs) with diameter down to 1.7 nm. The synergistic interplay between oleylamine and 1-dodecanethiol is crucial to yield these UNWs. The in situ formed amorphous hydroxide layers that is confined to the surface of the ultrathin scaffolds enable efficient oxygen evolution electrocatalysis. The UNWs exhibit a very low overpotential of 268 mV at 10 mA cm -2 in 0.1 m KOH, as well as remarkable long-term stability, representing one of the most efficient noble-metal-free catalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of user behavior on social networking sites

PubMed Central

2017-01-01

Social networking sites (SNS) are used for social and professional interaction with people. SNS popularity has encouraged researchers to analyze the relationship of activities performed on SNS with user behavior. In doing so, the term “user behavior” is rather used ambiguously with different interpretations, which makes it difficult to identify studies on user behavior in relation to SNS. This phenomenon has encouraged this thorough research on the characteristics of user behavior being discussed in the literature. Therefore, in this study, we aim to identify, analyze, and classify the characteristics associated with user behavior to answer the research questions designed to conduct this research. A mapping study (also called scoping study), which is a type of systematic literature review, is employed to identify potential studies from digital databases through a developed protocol. Thematic analysis is carried out for the classification of user behavior. We identified 116 primary studies for full analysis. This study found seven characteristics associated with behavior that have direct influence on SNS use and nine factors that have an indirect effect. All studies were conducted largely under seven areas that set the context of these studies. Findings show that the research on SNS is still in its early stage. The range of topics covered in the analyzed studies is quite expansive, although the depth in terms of number of studies under each topic is quite limited. This study reports that activities performed on SNS are either associated with user behavior or reflect personality characteristics. The findings of this study could be used by practitioners to evaluate their SNS platforms and develop more user-centered applications. These studies can also help organizations to understand better the needs of their employees. PMID:28151963

Investigation of user behavior on social networking sites.

PubMed

Waheed, Hajra; Anjum, Maria; Rehman, Mariam; Khawaja, Amina

2017-01-01

Social networking sites (SNS) are used for social and professional interaction with people. SNS popularity has encouraged researchers to analyze the relationship of activities performed on SNS with user behavior. In doing so, the term "user behavior" is rather used ambiguously with different interpretations, which makes it difficult to identify studies on user behavior in relation to SNS. This phenomenon has encouraged this thorough research on the characteristics of user behavior being discussed in the literature. Therefore, in this study, we aim to identify, analyze, and classify the characteristics associated with user behavior to answer the research questions designed to conduct this research. A mapping study (also called scoping study), which is a type of systematic literature review, is employed to identify potential studies from digital databases through a developed protocol. Thematic analysis is carried out for the classification of user behavior. We identified 116 primary studies for full analysis. This study found seven characteristics associated with behavior that have direct influence on SNS use and nine factors that have an indirect effect. All studies were conducted largely under seven areas that set the context of these studies. Findings show that the research on SNS is still in its early stage. The range of topics covered in the analyzed studies is quite expansive, although the depth in terms of number of studies under each topic is quite limited. This study reports that activities performed on SNS are either associated with user behavior or reflect personality characteristics. The findings of this study could be used by practitioners to evaluate their SNS platforms and develop more user-centered applications. These studies can also help organizations to understand better the needs of their employees.

Social networking sites (SNS); exploring their uses and associated value for adolescent mothers in Western Australia in terms of social support provision and building social capital.

PubMed

Nolan, Samantha; Hendricks, Joyce; Towell, Amanda

2015-09-01

to explore the use of social networking sites (SNS) by adolescent mothers in Western Australia (WA) in relation to social support and the building of social capital. a constructionist narrative inquiry approach was employed to guide the research design and processes. Approval was gained from the university human ethics department. Sampling was purposeful and data were collected using in-depth interviews with seven adolescent mothers in WA. interviews were undertaken within the homes of adolescent mothers across WA. from within three fundamental domains of social support; tangible, emotional and informational support, provided by SNS use, five key themes were identified from the narratives. 'Social connectedness' was identified as a form of tangible support, sometimes termed 'practical' or 'instrumental' support. This theme incorporates connectedness with family, friends, and peers and across new and existing social groups. Three themes were identified that relate to emotional support; 'increased parenting confidence'; 'reduced parental stress' and 'enhanced self-disclosure' afforded by use of SNS. 'Access to information' was identified in terms of informational support, with participants often highlighting SNS use as their primary portal for information and advice. the findings of this study suggest that SNS use affords adolescent mothers in WA access to tangible, informational and emotional support and thus is a valuable source of social capital for these mothers. This study provides a platform for further exploration into this phenomenon, and possible implications include the potential for midwives and health care professionals to promote the benefits of SNS use with, and for, this group of mothers, or to incorporate SNS use into modern health care practices to further develop the potential for improved social capital related outcomes for them. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photo-thermoelectric properties of SnS nanocrystals with orthorhombic layered structure

NASA Astrophysics Data System (ADS)

Hyun, Cheol-Min; Choi, Jeong-Hun; Lee, Myoung-Jae; Ahn, Ji-Hoon

2017-07-01

The photo-thermoelectric properties of SnS nanocrystals, two-dimensional materials with an orthorhombic symmetry, were investigated using a focused laser scanning method. The SnS nanocrystals were synthesized by a vapor transport method, and their fundamental material and electrical properties were investigated. Upon shining a laser onto the SnS channel region under a positive source-drain bias, a positive photocurrent was observed due to photo-excited electron-hole pairs. On the other hand, when this external electric field was not applied, a strong photocurrent was observed within the metal electrode region rather than at the metal-semiconductor interface, which indicated that the major mechanism for the photocurrent under zero external bias was a photo-induced thermoelectric effect rather than a photovoltaic effect. Moreover, the Seebeck coefficient of the SnS nanocrystal device was approximately 1735 μV/K, which is 3.5 times larger than that of its bulk counterpart.

Face-to-face or not-to-face: A technology preference for communication.

PubMed

Jaafar, Noor Ismawati; Darmawan, Bobby; Mohamed Ariffin, Mohd Yahya

2014-11-01

This study employed the Model of Technology Preference (MTP) to explain the relationship of the variables as the antecedents of behavioral intention to adopt a social networking site (SNS) for communication. Self-administered questionnaires were distributed to SNS account users using paper-based and web-based surveys that led to 514 valid responses. The data were analyzed using structural equation modeling (SEM). The results show that two out of three attributes of the attribute-based preference (ATRP) affect attitude-based preference (ATTP). The data support the hypotheses that perceived enjoyment and social presence are predictors of ATTP. In this study, the findings further indicated that ATTP has no relationship with the behavioral intention of using SNS, but it has a relationship with the attitude of using SNS. SNS development should provide features that ensure enjoyment and social presence for users to communicate instead of using the traditional face-to-face method of communication.

Effect of processing parameters on microstructure of MoS{sub 2} ultra-thin films synthesized by chemical vapor deposition method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Yang; You, Suping; Sun, Kewei

2015-06-15

MoS{sub 2} ultra-thin layers are synthesized using a chemical vapor deposition method based on the sulfurization of molybdenum trioxide (MoO{sub 3}). The ultra-thin layers are characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and atomic force microscope (AFM). Based on our experimental results, all the processing parameters, such as the tilt angle of substrate, applied voltage, heating time and the weight of source materials have effect on the microstructures of the layers. In this paper, the effects of such processing parameters on the crystal structures and morphologies of the as-grown layers are studied. It is found that the film obtainedmore » with the tilt angle of 0.06° is more uniform. A larger applied voltage is preferred to the growth of MoS{sub 2} thin films at a certain heating time. In order to obtain the ultra-thin layers of MoS{sub 2}, the weight of 0.003 g of source materials is preferred. Under our optimal experimental conditions, the surface of the film is smooth and composed of many uniformly distributed and aggregated particles, and the ultra-thin MoS{sub 2} atomic layers (1∼10 layers) covers an area of more than 2 mm×2 mm.« less

Tracking Stripped Proton Particles in SNS Ring Injection Momentum Dump Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jian-Guang

3D computer simulations are performed to study magnetic field distributions and particle trajectories along the SNS ring injection momentum dump line. Optical properties and transfer maps along the dump line are calculated. The stripped proton particle distributions on the dump window are analyzed. The study has provided useful information for the redesign of the SNS ring injection beam dump.

SNS Heterojunctions With New Combinations Of Materials

NASA Technical Reports Server (NTRS)

Vasquez, Richard P.; Hunt, Brian D.; Foote, Marc C.

1992-01-01

New combinations of materials proposed for superconductor/normal-metal/superconductor (SNS) heterojunctions in low-temperature electronic devices such as fast switches, magnetometers, and mixers. Epitaxial heterojunctions formed between high-temperature superconductors and either oxide semiconductors or metals. Concept offers alternative to other three-layer heterojunction concepts; physical principles of operation permit SNS devices to have thicker barrier layers and fabricated more easily.

A Personal Statement about a Four-Year Curriculum for Heritage and Native Speakers of Spanish Programs.

ERIC Educational Resources Information Center

Stering, Edward

This document shares a vision for a 4-year curriculum for Heritage Speakers of Spanish (HSS)/Spanish for Native Speakers (SNS), describing a course developed for SNS students within Mercy High School in San Francisco, California. The vision foresees an ever-increasing number of HSS and SNS students completing college level degree programs then…

Exploring the Usefulness of School Education about Risks on Social Network Sites: A Survey Study

ERIC Educational Resources Information Center

Vanderhoven, Ellen; Schellens, Tammy; Valcke, Martin

2013-01-01

The growing popularity of social network sites (SNS) is causing concerns about privacy and security, especially with teenagers, since they show various forms of unsafe behavior on SNS. It has been put forth by researchers, teachers, parents, and teenagers that school is ideally placed to educate teens about risks on SNS and to teach youngsters how…

Shadow netWorkspace: An Open Source Intranet for Learning Communities

ERIC Educational Resources Information Center

Laffey, James M.; Musser, Dale

2006-01-01

Shadow netWorkspace (SNS) is a web application system that allows a school or any type of community to establish an intranet with network workspaces for all members and groups. The goal of SNS has been to make it easy for schools and other educational organizations to provide network services in support of implementing a learning community. SNS is…

The absorption, distribution, excretion and toxicity of mesoporous silica nanoparticles in mice following different exposure routes.

PubMed

Fu, Changhui; Liu, Tianlong; Li, Linlin; Liu, Huiyu; Chen, Dong; Tang, Fangqiong

2013-03-01

Mesoporous silica nanoparticles (MSNs) are emerging as one of the promising nanomaterials for biomedical applications, but the nanomaterials-body interaction exposed by different administration routes remained poorly understood. In the present study, a systematic investigation of the absorption, distribution, excretion and toxicity of silica nanoparticles (SNs) with the average size of 110 nm after four different exposure routes including intravenous, hypodermic, intramuscular injection and oral administration to mice were achieved. The results showed that a fraction of the SNs administrated by the intramuscular and hypodermic injection could cross different biological barriers into the liver but with a low absorption rate. Exposing by oral administration, SNs were absorbed into the intestinal tract and persisted in the liver. And SNs administrated by intravenous injection were mainly present in the liver and spleen. In addition, SNs could cause inflammatory response around the injection sites after intramuscular and hypodermic injection. It was also found that SNs were mainly excreted through urine and feces after different exposure routes. This study will be helpful for selecting the appropriate exposed routes for the development of nanomaterials-based drug delivery system for biomedical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hemispheric Sunspot Unit Area: Comparison with Hemispheric Sunspot Number and Sunspot Area

NASA Astrophysics Data System (ADS)

Li, K. J.; Xiang, N. B.; Qu, Z. N.; Xie, J. L.

2014-03-01

The monthly mean northern and southern hemispheric sunspot numbers (SNs) and sunspot areas (SAs) in the time interval of 1945 January to 2012 December are utilized to construct the monthly northern and southern hemispheric sunspot unit areas (SUAs), which are defined as the ratio of hemispheric SA to SN. Hemispheric SUAs are usually found to rise at the beginning and to fall at the ending time of a solar cycle more rapidly, forming a more irregular cycle profile than hemispheric SNs and SAs, although it also presents Schwabe-cycle-like hemispheric SNs and SAs. Sunspot activity (SN, SA, and SUA) is found asynchronously and is asymmetrically distributed in the northern and southern hemispheres, and hemispheric SNs, SAs, and SUAs are not in phase in the two hemispheres. The similarity of hemispheric SNs and SAs is found to be much more obvious than that of hemispheric SUAs and SNs (or SAs), and also for their north-south asymmetry. A notable feature is found for the behavior of the SUA around the minimum time of cycle 24: the SUA rapidly decreases from the cycle maximum value to the cycle minimum value of sunspot cycles 19-24 within just 22 months.

Hemispheric sunspot unit area: comparison with hemispheric sunspot number and sunspot area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, K. J.; Xiang, N. B.; Qu, Z. N.

2014-03-01

The monthly mean northern and southern hemispheric sunspot numbers (SNs) and sunspot areas (SAs) in the time interval of 1945 January to 2012 December are utilized to construct the monthly northern and southern hemispheric sunspot unit areas (SUAs), which are defined as the ratio of hemispheric SA to SN. Hemispheric SUAs are usually found to rise at the beginning and to fall at the ending time of a solar cycle more rapidly, forming a more irregular cycle profile than hemispheric SNs and SAs, although it also presents Schwabe-cycle-like hemispheric SNs and SAs. Sunspot activity (SN, SA, and SUA) is foundmore » asynchronously and is asymmetrically distributed in the northern and southern hemispheres, and hemispheric SNs, SAs, and SUAs are not in phase in the two hemispheres. The similarity of hemispheric SNs and SAs is found to be much more obvious than that of hemispheric SUAs and SNs (or SAs), and also for their north-south asymmetry. A notable feature is found for the behavior of the SUA around the minimum time of cycle 24: the SUA rapidly decreases from the cycle maximum value to the cycle minimum value of sunspot cycles 19-24 within just 22 months.« less

Segregation of chlorine in n-type tin monosulfide ceramics: Actual chlorine concentration for carrier-type conversion

NASA Astrophysics Data System (ADS)

Iguchi, Yuki; Sugiyama, Taiki; Inoue, Kazutoshi; Yanagi, Hiroshi

2018-05-01

Tin monosulfide (SnS) is an attractive material for photovoltaic cells because of its suitable band-gap energy, high absorption coefficient, and non-toxic and abundant constituent elements. The primary drawback of this material is the lack of n-type SnS. We recently demonstrated n-type SnS by doping with Cl. However, the Cl-doped n-type SnS bulk ceramics exhibited an odd behavior in which carrier-type conversion but not electron carrier concentration depended on the Cl concentration. In this study, the electron probe microanalysis (EPMA) elemental mapping of Cl-doped SnS revealed continuous homogeneous regions with a relatively low Cl concentration along with the islands of high Cl concentration in which Sn/S is far from unity. The difference between the Cl concentration in the homogeneous region (determined by EPMA) and the bulk Cl concentration (determined by wavelength-dispersive X-ray fluorescence spectroscopy) increased with the increasing Cl doping amount. The carrier concentration and the Hall coefficient clearly depended on the Cl concentration in the homogeneous region. Carrier-type conversion was observed at the Cl concentration of 0.26 at. % (in the homogeneous region).

Correlates of Health-Related Social Media Use Among Adults

PubMed Central

2013-01-01

Background Sixty percent of Internet users report using the Internet to look for health information. Social media sites are emerging as a potential source for online health information. However, little is known about how people use social media for such purposes. Objectives The purpose of this study was two-fold: (1) to establish the frequency of various types of online health-seeking behaviors, and (2) to identify correlates of 2 health-related online activities, social networking sites (SNS) for health-related activities and consulting online user-generated content for answers about health care providers, health facilities, or medical treatment. Methods The study consisted of a telephone survey of 1745 adults who reported going online to look for health-related information. Four subscales were created to measure use of online resources for (1) using SNS for health-related activities; (2) consulting online rankings and reviews of doctors, hospitals or medical facilities, and drugs or medical treatments; (3) posting a review online of doctors, hospitals or medical facilities, and drugs or medical treatments, and (4) posting a comment or question about health or medical issues on various social media. Univariate and multivariate logistic regression analyses were performed. Results Respondents consulted online rankings or reviews (41.15%), used SNS for health (31.58%), posted reviews (9.91%), and posted a comment, question, or information (15.19%). Respondents with a chronic disease were nearly twice as likely to consult online rankings (odds ratio [OR] 2.09, 95% CI 1.66-2.63, P<.001). Lower odds of consulting online reviews were associated with less formal education (OR 0.49, 95% CI 0.37-0.65, P<.001) and being male (OR 0.71, 95% CI 0.57-0.87, P<.001). Respondents with higher incomes were 1.5 times as likely to consult online rankings or reviews (OR 1.49, 95% CI 0.10-2.24, P=.05), than respondents with a regular provider (OR 2.05, 95% CI 1.52-2.78, P<.001), or living in an urban/suburban location (OR 1.61, 95% CI 1.17-2.22, P<.001). Older respondents were less likely to use SNS for health-related activities (OR 0.96, 95% CI 0.95-0.97, P<.001), as were males (OR 0.70, 95% CI 0.56-0.87, P<.001), whereas respondents with a regular provider had nearly twice the likelihood of using SNS for health-related activities (OR 1.89, 95% CI 1.43-2.52, P<.001). Conclusions People are using social media for seeking health information. However, individuals are more likely to consume information than they are to contribute to the dialog. The inherent value of “social” in social media is not being captured with online health information seeking. People with a regular health care provider, chronic disease, and those in younger age groups are more likely to consult online rankings and reviews and use SNS for health-related activities. PMID:23367505

Correlates of health-related social media use among adults.

PubMed

Thackeray, Rosemary; Crookston, Benjamin T; West, Joshua H

2013-01-30

Sixty percent of Internet users report using the Internet to look for health information. Social media sites are emerging as a potential source for online health information. However, little is known about how people use social media for such purposes. The purpose of this study was two-fold: (1) to establish the frequency of various types of online health-seeking behaviors, and (2) to identify correlates of 2 health-related online activities, social networking sites (SNS) for health-related activities and consulting online user-generated content for answers about health care providers, health facilities, or medical treatment. The study consisted of a telephone survey of 1745 adults who reported going online to look for health-related information. Four subscales were created to measure use of online resources for (1) using SNS for health-related activities; (2) consulting online rankings and reviews of doctors, hospitals or medical facilities, and drugs or medical treatments; (3) posting a review online of doctors, hospitals or medical facilities, and drugs or medical treatments, and (4) posting a comment or question about health or medical issues on various social media. Univariate and multivariate logistic regression analyses were performed. Respondents consulted online rankings or reviews (41.15%), used SNS for health (31.58%), posted reviews (9.9%1), and posted a comment, question, or information (15.19%). Respondents with a chronic disease were nearly twice as likely to consult online rankings (odds ratio [OR] 2.09, 95% CI 1.66-2.63, P<.001). Lower odds of consulting online reviews were associated with less formal education (OR 0.49, 95% CI 0.37-0.65, P<.001) and being male (OR 0.71, 95% CI 0.57-0.87, P<.001). Respondents with higher incomes were 1.5 times as likely to consult online rankings or reviews (OR 1.49, 95% CI 0.10-2.24, P=.05), than respondents with a regular provider (OR 2.05, 95% CI 1.52-2.78, P<.001), or living in an urban/suburban location (OR 1.61, 95% CI 1.17-2.22, P<.001). Older respondents were less likely to use SNS for health-related activities (OR 0.96, 95% CI 0.95-0.97, P<.001), as were males (OR 0.70, 95% CI 0.56-0.87, P<.001), whereas respondents with a regular provider had nearly twice the likelihood of using SNS for health-related activities (OR 1.89, 95% CI 1.43-2.52, P<.001). People are using social media for seeking health information. However, individuals are more likely to consume information than they are to contribute to the dialog. The inherent value of "social" in social media is not being captured with online health information seeking. People with a regular health care provider, chronic disease, and those in younger age groups are more likely to consult online rankings and reviews and use SNS for health-related activities.

Sodium-Doped Mesoporous Ni2P2O7 Hexagonal Tablets for High-Performance Flexible All-Solid-State Hybrid Supercapacitors.

PubMed

Wei, Chengzhen; Cheng, Cheng; Wang, Shanshan; Xu, Yazhou; Wang, Jindi; Pang, Huan

2015-08-01

A simple hydrothermal method has been developed to prepare hexagonal tablet precursors, which are then transformed into porous sodium-doped Ni2P2O7 hexagonal tablets by a simple calcination method. The obtained samples were evaluated as electrode materials for supercapacitors. Electrochemical measurements show that the electrode based on the porous sodium-doped Ni2P2O7 hexagonal tablets exhibits a specific capacitance of 557.7 F g(-1) at a current density of 1.2 A g(-1) . Furthermore, the porous sodium-doped Ni2P2O7 hexagonal tablets were successfully used to construct flexible solid-state hybrid supercapacitors. The device is highly flexible and achieves a maximum energy density of 23.4 Wh kg(-1) and a good cycling stability after 5000 cycles, which confirms that the porous sodium-doped Ni2P2 O7 hexagonal tablets are promising active materials for flexible supercapacitors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improving the accuracy of Møller-Plesset perturbation theory with neural networks

NASA Astrophysics Data System (ADS)

McGibbon, Robert T.; Taube, Andrew G.; Donchev, Alexander G.; Siva, Karthik; Hernández, Felipe; Hargus, Cory; Law, Ka-Hei; Klepeis, John L.; Shaw, David E.

2017-10-01

Noncovalent interactions are of fundamental importance across the disciplines of chemistry, materials science, and biology. Quantum chemical calculations on noncovalently bound complexes, which allow for the quantification of properties such as binding energies and geometries, play an essential role in advancing our understanding of, and building models for, a vast array of complex processes involving molecular association or self-assembly. Because of its relatively modest computational cost, second-order Møller-Plesset perturbation (MP2) theory is one of the most widely used methods in quantum chemistry for studying noncovalent interactions. MP2 is, however, plagued by serious errors due to its incomplete treatment of electron correlation, especially when modeling van der Waals interactions and π-stacked complexes. Here we present spin-network-scaled MP2 (SNS-MP2), a new semi-empirical MP2-based method for dimer interaction-energy calculations. To correct for errors in MP2, SNS-MP2 uses quantum chemical features of the complex under study in conjunction with a neural network to reweight terms appearing in the total MP2 interaction energy. The method has been trained on a new data set consisting of over 200 000 complete basis set (CBS)-extrapolated coupled-cluster interaction energies, which are considered the gold standard for chemical accuracy. SNS-MP2 predicts gold-standard binding energies of unseen test compounds with a mean absolute error of 0.04 kcal mol-1 (root-mean-square error 0.09 kcal mol-1), a 6- to 7-fold improvement over MP2. To the best of our knowledge, its accuracy exceeds that of all extant density functional theory- and wavefunction-based methods of similar computational cost, and is very close to the intrinsic accuracy of our benchmark coupled-cluster methodology itself. Furthermore, SNS-MP2 provides reliable per-conformation confidence intervals on the predicted interaction energies, a feature not available from any alternative method.

Improving the accuracy of Møller-Plesset perturbation theory with neural networks.

PubMed

McGibbon, Robert T; Taube, Andrew G; Donchev, Alexander G; Siva, Karthik; Hernández, Felipe; Hargus, Cory; Law, Ka-Hei; Klepeis, John L; Shaw, David E

2017-10-28

Noncovalent interactions are of fundamental importance across the disciplines of chemistry, materials science, and biology. Quantum chemical calculations on noncovalently bound complexes, which allow for the quantification of properties such as binding energies and geometries, play an essential role in advancing our understanding of, and building models for, a vast array of complex processes involving molecular association or self-assembly. Because of its relatively modest computational cost, second-order Møller-Plesset perturbation (MP2) theory is one of the most widely used methods in quantum chemistry for studying noncovalent interactions. MP2 is, however, plagued by serious errors due to its incomplete treatment of electron correlation, especially when modeling van der Waals interactions and π-stacked complexes. Here we present spin-network-scaled MP2 (SNS-MP2), a new semi-empirical MP2-based method for dimer interaction-energy calculations. To correct for errors in MP2, SNS-MP2 uses quantum chemical features of the complex under study in conjunction with a neural network to reweight terms appearing in the total MP2 interaction energy. The method has been trained on a new data set consisting of over 200 000 complete basis set (CBS)-extrapolated coupled-cluster interaction energies, which are considered the gold standard for chemical accuracy. SNS-MP2 predicts gold-standard binding energies of unseen test compounds with a mean absolute error of 0.04 kcal mol -1 (root-mean-square error 0.09 kcal mol -1 ), a 6- to 7-fold improvement over MP2. To the best of our knowledge, its accuracy exceeds that of all extant density functional theory- and wavefunction-based methods of similar computational cost, and is very close to the intrinsic accuracy of our benchmark coupled-cluster methodology itself. Furthermore, SNS-MP2 provides reliable per-conformation confidence intervals on the predicted interaction energies, a feature not available from any alternative method.

Ultrathin and Atomically Flat Transition-Metal Oxide: Promising Building Blocks for Metal-Insulator Electronics.

PubMed

Cui, Qingsong; Sakhdari, Maryam; Chamlagain, Bhim; Chuang, Hsun-Jen; Liu, Yi; Cheng, Mark Ming-Cheng; Zhou, Zhixian; Chen, Pai-Yen

2016-12-21

We present a new and viable template-assisted thermal synthesis method for preparing amorphous ultrathin transition-metal oxides (TMOs) such as TiO 2 and Ta 2 O 5 , which are converted from crystalline two-dimensional (2D) transition-metal dichalcogenides (TMDs) down to a few atomic layers. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM) were used to characterize the chemical composition and bonding, surface morphology, and atomic structure of these ultrathin amorphous materials to validate the effectiveness of our synthesis approach. Furthermore, we have fabricated metal-insulator-metal (MIM) diodes using the TiO 2 and Ta 2 O 5 as ultrathin insulating layers with low potential barrier heights. Our MIM diodes show a clear transition from direct tunneling to Fowler-Nordheim tunneling, which was not observed in previously reported MIM diodes with TiO 2 or Ta 2 O 5 as the insulating layer. We attribute the improved performance of our MIM diodes to the excellent flatness and low pinhole/defect densities in our TMO insulting layers converted from 2D TMDs, which enable the low-threshold and controllable electron tunneling transport. We envision that it is possible to use the ultrathin TMOs converted from 2D TMDs as the insulating layer of a wide variety of metal-insulator and field-effect electronic devices for various applications ranging from microwave mixing, parametric conversion, infrared photodetection, emissive energy harvesting, to ultrafast electronic switching.

The formation of α-phase SnS nanostructure from a hybrid, multi-layered S/Sn/S/Sn/S thin films: Phase stability, surface morphology and optical studies

NASA Astrophysics Data System (ADS)

Baby, Benjamin Hudson; Bharathi Mohan, D.

2017-11-01

Single phase of SnS thin film was fabricated from S/Sn/S/Sn/S multilayer prepared by using atmospheric pressure and vacuum thermal evaporation methods Glancing angle high vacuum thermal evaporation technique was employed to grow Sn nanorods which facilitated the sulphur diffusion in a faster manner to prepare SnS nanoparticles. The sulphur deposition temperature, sulphur deposition time and tin deposition time were successfully tailored in the synthesis process and stabilized α-phase SnS by probing through confocal micro-Raman spectrometer. X-ray diffraction confirms the formation of SnS crystal structure at sulphur deposition temperature 200 °C. The mechanism of formation of highly porous SnS phase with flower like morphology is explained from the morphological analysis of post deposition annealed film. The complete absence of any oxidation state as evident from Raman as well as EDAX analysis confirms that the proposed sulphurization method could be a suitable, simple and cheap technique for the successful sulphurization of metal films. Band gap calculation from Tauc plot showed a direct band gap value of 1.5 eV for films with single phase of SnS which can be used as a p-type absorber layer in thin film solar cells. Emission studies showed the energy transitions attributed to band edge transition and due to the presence of intrinsic defects.

Influence of Thickness on the Electrical Transport Properties of Exfoliated Bi2Te3 Ultrathin Films

NASA Astrophysics Data System (ADS)

Mo, D. L.; Wang, W. B.; Cai, Q.

2016-08-01

In this work, the mechanical exfoliation method has been utilized to fabricate Bi2Te3 ultrathin films. The thickness of the ultrathin films is revealed to be several tens of nanometers. Weak antilocalization effects and Shubnikov de Haas oscillations have been observed in the magneto-transport measurements on individual films with different thickness, and the two-dimensional surface conduction plays a dominant role. The Fermi level is found to be 81 meV above the Dirac point, and the carrier mobility can reach ~6030 cm2/(Vs) for the 10-nm film. When the film thickness decreases from 30 to 10 nm, the Fermi level will move 8 meV far from the bulk valence band. The coefficient α in the Hikami-Larkin-Nagaoka equation is shown to be ~0.5, manifesting that only the bottom surface of the Bi2Te3 ultrathin films takes part in transport conductions. These will pave the way for understanding thoroughly the surface transport properties of topological insulators.

320-nm Flexible Solution-Processed 2,7-dioctyl[1] benzothieno[3,2-b]benzothiophene Transistors.

PubMed

Ren, Hang; Tang, Qingxin; Tong, Yanhong; Liu, Yichun

2017-08-09

Flexible organic thin-film transistors (OTFTs) have received extensive attention due to their outstanding advantages such as light weight, low cost, flexibility, large-area fabrication, and compatibility with solution-processed techniques. However, compared with a rigid substrate, it still remains a challenge to obtain good device performance by directly depositing solution-processed organic semiconductors onto an ultrathin plastic substrate. In this work, ultrathin flexible OTFTs are successfully fabricated based on spin-coated 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) films. The resulting device thickness is only ~320 nm, so the device has the ability to adhere well to a three-dimension curved surface. The ultrathin C8-BTBT OTFTs exhibit a mobility as high as 4.36 cm² V -1 s -1 and an on/off current ratio of over 10⁶. These results indicate the substantial promise of our ultrathin flexible C8-BTBT OTFTs for next-generation flexible and conformal electronic devices.

Ultrathin Shape Change Smart Materials.

PubMed

Xu, Weinan; Kwok, Kam Sang; Gracias, David H

2018-02-20

With the discovery of graphene, significant research has focused on the synthesis, characterization, and applications of ultrathin materials. Graphene has also brought into focus other ultrathin materials composed of organics, polymers, inorganics, and their hybrids. Together, these ultrathin materials have unique properties of broad significance. For example, ultrathin materials have a large surface area and high flexibility which can enhance conformal contact in wearables and sensors leading to improved sensitivity. When porous, the short transverse diffusion length in these materials allows rapid mass transport. Alternatively, when impermeable, these materials behave as an ultrathin barrier. Such controlled permeability is critical in the design of encapsulation and drug delivery systems. Finally, ultrathin materials often feature defect-free and single-crystal-like two-dimensional atomic structures resulting in superior mechanical, optical, and electrical properties. A unique property of ultrathin materials is their low bending rigidity, which suggests that they could easily be bent, curved, or folded into 3D shapes. In this Account, we review the emerging field of 2D to 3D shape transformations of ultrathin materials. We broadly define ultrathin to include materials with a thickness below 100 nm and composed of a range of organic, inorganic, and hybrid compositions. This topic is important for both fundamental and applied reasons. Fundamentally, bending and curving of ultrathin films can cause atomistic and molecular strain which can alter their physical and chemical properties and lead to new 3D forms of matter which behave very differently from their planar precursors. Shape change can also lead to new 3D architectures with significantly smaller form factors. For example, 3D ultrathin materials would occupy a smaller space in on-chip devices or could permeate through tortuous media which is important for miniaturized robots and smart dust applications. Our Account highlights several differences between ultrathin and traditional shape change materials. The latter is typically associated with hydrogels, liquid crystals, or shape memory elastomers. As compared to bulk materials, ultrathin materials can much more easily bend and fold due to the significantly reduced bending modulus. Consequently, it takes much less energy to alter the shape of ultrathin materials, and even small environmental stimuli can trigger a large response. Further, the energy barriers between different configurations are small which allow a variety of conformations and enhances programmability. Finally, due to their ultrathin nature, the shape changes are typically not slowed down by sluggish mass or thermal transport, and thus, responses can be much faster than those of bulk materials. The latter point is important in the design of high-speed actuators. Consequently, ultrathin materials could enable low-power, rapid, programmable, and complex shape transformations in response to a broad range of stimuli such as pH, temperature, electromagnetic fields, or chemical environments. The Account also includes a discussion of applications, important challenges, and future directions.

Free-standing ultrathin CoMn2O4 nanosheets anchored on reduced graphene oxide for high-performance supercapacitors.

PubMed

Gao, Guoxin; Lu, Shiyao; Xiang, Yang; Dong, Bitao; Yan, Wei; Ding, Shujiang

2015-11-21

Ultrathin CoMn2O4 nanosheets supported on reduced graphene oxide (rGO) are successfully synthesized through a simple co-precipitation method with a post-annealing treatment. With the assistance of citrate, the free-standing CoMn2O4 ultrathin nanosheets can form porous overlays on both sides of the rGO sheets. Such a novel hybrid nanostructure can effectively promote charge transport and accommodate volume variation upon prolonged charge/discharge cycling. When evaluated as a promising electrode for supercapacitors in a 6 M KOH solution electrolyte, the hybrid nanocomposites demonstrate highly enhanced capacitance and excellent cycling stability.

How Relations are Built within a SNS World -- Social Network Analysis on Mixi --

NASA Astrophysics Data System (ADS)

Matsuo, Yutaka; Yasud, Yuki

Our purpose here is to (1) investigate the structure of the personal networks developed on mixi, a Japanese social networking service (SNS), and (2) to consider the governing mechanism which guides participants of a SNS to form an aggregate network. Our findings are as follows:the clustering coefficient of the network is as high as 0.33 while the characteristic path lenght is as low as 5.5. A network among central users (over 300 edges) consist of two cliques, which seems to be very fragile. Community-affiliation network suggests there are several easy-entry communities which later lead users to more high-entry, unique-theme communities. The analysis on connectedness within a community reveals the importance of real-world interaction. Lastly, we depict a probable image of the entire ecology on {\\\\em mixi} among users and communities, which contributes broadly to social systems on the Web.

The association between exposure to social media alcohol marketing and youth alcohol use behaviors in India and Australia.

PubMed

Gupta, Himanshu; Lam, Tina; Pettigrew, Simone; Tait, Robert J

2018-06-13

Alcohol marketing on social networking sites (SNS) is associated with alcohol use among young people. Alcohol companies adapt their online marketing content to specific national contexts and responses to such content differ by national settings. However, there exists very little academic work comparing the association between alcohol marketing on SNS and alcohol use among young people in different national settings and across different SNS. Therefore, we aimed to extend the limited existing work by investigating and comparing the association between self-reported exposure to alcohol marketing on three leading SNS (Facebook, YouTube, and Twitter) and alcohol use among young people in diverse national contexts (India and Australia). Cross-sectional, self-report data were obtained from a convenience sample of 631 respondents (330 in India; 301 in Australia) aged 13-25 years via online surveys. Respondents answered questions on their drinking behaviors and involvement with alcohol marketing on SNS. Many respondents from both countries reported interacting with alcohol content online, predominantly on Facebook, followed by YouTube and then Twitter. The interaction was primarily in the forms of posting/liking/sharing/commenting on items posted on alcohol companies' social media accounts, viewing the event page/attending the event advertised by an alcohol company via social media, and/or accessing an alcohol website. Multivariate analyses demonstrated significant associations between respondents' interaction with alcohol content and drinking levels, with effects differing by SNS, demographic group, and country. For example, having friends who shared alcohol-related content was an important predictor of usual alcohol consumption for Indian respondents (p < .001), whereas posting alcohol-related information themselves was a stronger predictor among Australians (p < .001). The results suggest that interaction with alcohol-related content on SNS is associated with young people's alcohol use behaviors and that these behaviors vary by national settings. This study extends previous work by demonstrating this connection across varying social media platforms and national contexts. The results highlight the need to formulate and implement strategies to effectively regulate the SNS alcohol marketing, especially among younger SNS users.

Systematic errors in regional climate model RegCM over Europe and sensitivity to variations in PBL parameterizations

NASA Astrophysics Data System (ADS)

Güttler, I.

2012-04-01

Systematic errors in near-surface temperature (T2m), total cloud cover (CLD), shortwave albedo (ALB) and surface net longwave (SNL) and shortwave energy flux (SNS) are detected in simulations of RegCM on 50 km resolution over the European CORDEX domain when forced with ERA-Interim reanalysis. Simulated T2m is compared to CRU 3.0 and other variables to GEWEX-SRB 3.0 dataset. Most of systematic errors found in SNL and SNS are consistent with errors in T2m, CLD and ALB: they include prevailing negative errors in T2m and positive errors in CLD present during most of the year. Errors in T2m and CLD can be associated with the overestimation of SNL and SNS in most simulations. Impact of errors in albedo are primarily confined to north Africa, where e.g. underestimation of albedo in JJA is consistent with associated surface heating and positive SNS and T2m errors. Sensitivity to the choice of the PBL scheme and various parameters in PBL schemes is examined from an ensemble of 20 simulations. The recently implemented prognostic PBL scheme performs over Europe with a mixed success when compared to standard diagnostic scheme with a general increase of errors in T2m and CLD over all of the domain. Nevertheless, the improvements in T2m can be found in e.g. north-eastern Europe during DJF and western Europe during JJA where substantial warm biases existed in simulations with the diagnostic scheme. The most detectable impact, in terms of the JJA T2m errors over western Europe, comes form the variation in the formulation of mixing length. In order to reduce the above errors an update of the RegCM albedo values and further work in customizing PBL scheme is suggested.

Enhanced magnetic moment in ultrathin Fe-doped CoFe2O4 films

NASA Astrophysics Data System (ADS)

Moyer, J. A.; Vaz, C. A. F.; Kumah, D. P.; Arena, D. A.; Henrich, V. E.

2012-11-01

The effect of film thickness on the magnetic properties of ultrathin Fe-doped cobalt ferrite (Co1-xFe2+xO4) grown on MgO (001) substrates is investigated by superconducting quantum interference device magnetometry and x-ray magnetic linear dichroism, while the distribution of the Co2+ cations between the octahedral and tetrahedral lattice sites is studied with x-ray absorption spectroscopy. For films thinner than 10 nm, there is a large enhancement of the magnetic moment; conversely, the remanent magnetization and coercive fields both decrease, while the magnetic spin axes of all the cations become less aligned with the [001] crystal direction. In particular, at 300 K the coercive fields of the thinnest films vanish. The spectroscopy data show that no changes occur in the cation distribution as a function of film thickness, ruling this out as the origin of the enhanced magnetic moment. However, the magnetic measurements all support the possibility that these ultrathin Fe-doped CoFe2O4 films are transitioning into a superparamagnetic state, as has been seen in ultrathin Fe3O4. A weakening of the magnetic interactions at the antiphase boundaries, leading to magnetically independent domains within the film, could explain the enhanced magnetic moment in ultrathin Fe-doped CoFe2O4 and the onset of superparamagnetism at room temperature.

Overcoming the efficiency limitations of SnS2 nanoparticle-based bulk heterojunction solar cells

NASA Astrophysics Data System (ADS)

Tam Nguyen Truong, Nguyen; Kieu Trinh, Thanh; Thanh Hau Pham, Viet; Smith, Ryan P.; Park, Chinho

2018-04-01

This study examined the effects of heat treatment, the electron transport layer, and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) incorporation on the performance of hybrid bulk heterojunction (BHJ) solar cells composed of tin disulfide (SnS2) nanoparticles (NPs) and low band gap energy polymers poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b3,4-b‧]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) or poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PBT7). Inserting an electron transport layer (ETL) (i.e., ZnO) on the top of the photoactive layer improved the surface morphology of the photoactive layer, which led to an improvement in charge transport. Moreover, adding a suitable amount of PCBM to the SnS2/polymer active layer enhanced the device performance, such as short circuit current density (J sc) and power conversion efficiency (PCE). In particular, adding 0.5 mg of PCBM to the composite solution led to a 25% and 1.5% improvement in the J sc value and PCE, respectively. The enhanced performance was due mainly to the improvements in the surface morphology of the photoactive layer, charge carrier mobility within the donor-acceptor interface, and carrier collection efficiency at the cathode.

SnO{sub 2} films: In-situ template-sacrificial growth and photovoltaic property based on SnO{sub 2}/poly(3-hexyl-thiophene) for hybrid solar cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yange, E-mail: zhangygzhang@163.com; Li, Pinjiang; Xu, Xiaoyun

2015-10-15

Highlights: • SnO{sub 2} nanocrystals/thin films were fabricated on ITO glass substrate from preformed SnS thin film as sacrificial template. • The SnO{sub 2} film and SnO{sub 2}/P3HT was characterized by several techniques. • The new hybrid solar cell device was based on the hybrid thin film of SnO{sub 2} NCs and P3HT composites. - Abstract: we described a facile in-situ wet chemical method to prepare SnO{sub 2} thin film on ITO glass substrate from preformed SnS thin film as sacrificial template. The chemical conversion process of SnS to SnO{sub 2} was studied. The SnO{sub 2} film and SnO{sub 2}/P3HTmore » was characterized by several techniques, such as powder X-ray diffract meter (XRD), Raman spectrometer, scanning electron microscope (SEM), atomic force microscope (AFM) and UV–vis spectrophotometer in detail. The new SnO{sub 2}/P3HT hybrid solar cell device showed an open-circuit voltage of 0.185 V, a short-circuit current density of 0.366 mA/cm{sup 2} and a fill factor of 0.247, corresponding to a power conversion efficiency of 0.0167%.« less

Ultrathin nondoped emissive layers for efficient and simple monochrome and white organic light-emitting diodes.

PubMed

Zhao, Yongbiao; Chen, Jiangshan; Ma, Dongge

2013-02-01

In this paper, highly efficient and simple monochrome blue, green, orange, and red organic light emitting diodes (OLEDs) based on ultrathin nondoped emissive layers (EMLs) have been reported. The ultrathin nondoped EML was constructed by introducing a 0.1 nm thin layer of pure phosphorescent dyes between a hole transporting layer and an electron transporting layer. The maximum external quantum efficiencies (EQEs) reached 17.1%, 20.9%, 17.3%, and 19.2% for blue, green, orange, and red monochrome OLEDs, respectively, indicating the universality of the ultrathin nondoped EML for most phosphorescent dyes. On the basis of this, simple white OLED structures are also demonstrated. The demonstrated complementary blue/orange, three primary blue/green/red, and four color blue/green/orange/red white OLEDs show high efficiency and good white emission, indicating the advantage of ultrathin nondoped EMLs on constructing simple and efficient white OLEDs.

Overview of ten-year operation of the superconducting linear accelerator at the Spallation Neutron Source

NASA Astrophysics Data System (ADS)

Kim, S.-H.; Afanador, R.; Barnhart, D. L.; Crofford, M.; Degraff, B. D.; Doleans, M.; Galambos, J.; Gold, S. W.; Howell, M. P.; Mammosser, J.; McMahan, C. J.; Neustadt, T. S.; Peters, C.; Saunders, J. W.; Strong, W. H.; Vandygriff, D. J.; Vandygriff, D. M.

2017-04-01

The Spallation Neutron Source (SNS) has acquired extensive operational experience of a pulsed proton superconducting linear accelerator (SCL) as a user facility. Numerous lessons have been learned in its first 10 years operation to achieve a stable and reliable operation of the SCL. In this paper, an overview of the SNS SCL design, qualification of superconducting radio frequency (SRF) cavities and ancillary subsystems, an overview of the SNS cryogenic system, the SCL operation including SCL output energy history and downtime statistics, performance stability of the SRF cavities, efforts for SRF cavity performance recovery and improvement at the SNS, and maintenance activities for cryomodules are introduced.

Overview of ten-year operation of the superconducting linear accelerator at the Spallation Neutron Source

DOE PAGES

Kim, Sang-Ho; Afanador, Ralph; Barnhart, Debra L.; ...

2017-02-04

The Spallation Neutron Source (SNS) has acquired extensive operational experience of a pulsed proton superconducting linear accelerator (SCL) as a user facility. Numerous lessons have been learned in its first 10 years operation to achieve a stable and reliable operation of the SCL. In this paper, an overview of the SNS SCL design, qualification of superconducting radio frequency (SRF) cavities and ancillary subsystems, an overview of the SNS cryogenic system, the SCL operation including SCL output energy history and downtime statistics, performance stability of the SRF cavities, efforts for SRF cavity performance recovery and improvement at the SNS, and maintenancemore » activities for cryomodules are introduced.« less

Overview of ten-year operation of the superconducting linear accelerator at the Spallation Neutron Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Sang-Ho; Afanador, Ralph; Barnhart, Debra L.

The Spallation Neutron Source (SNS) has acquired extensive operational experience of a pulsed proton superconducting linear accelerator (SCL) as a user facility. Numerous lessons have been learned in its first 10 years operation to achieve a stable and reliable operation of the SCL. In this paper, an overview of the SNS SCL design, qualification of superconducting radio frequency (SRF) cavities and ancillary subsystems, an overview of the SNS cryogenic system, the SCL operation including SCL output energy history and downtime statistics, performance stability of the SRF cavities, efforts for SRF cavity performance recovery and improvement at the SNS, and maintenancemore » activities for cryomodules are introduced.« less

Ultralow-loss polaritons in isotopically pure boron nitride

DOE PAGES

Giles, Alexander J.; Dai, Siyuan; Vurgaftman, Igor; ...

2017-12-11

Conventional optical components are limited to size scales much larger than the wavelength of light, as changes to the amplitude, phase and polarization of the electromagnetic fields are accrued gradually along an optical path. However, advances in nanophotonics have produced ultrathin, so-called ‘flat’ optical components that beget abrupt changes in these properties over distances significantly shorter than the free-space wavelength. Although high optical losses still plague many approaches, phonon polariton (PhP) materials have demonstrated long lifetimes for sub-diffractional modes in comparison to plasmon-polariton-based nanophotonics. We experimentally observe a threefold improvement in polariton lifetime through isotopic enrichment of hexagonal boron nitridemore » (hBN). Commensurate increases in the polariton propagation length are demonstrated via direct imaging of polaritonic standing waves by means of infrared nano-optics. Lastly, our results provide the foundation for a materials-growth-directed approach aimed at realizing the loss control necessary for the development of PhP-based nanophotonic devices.« less

Edge Delamination of Monolayer Transition Metal Dichalcogenides.

PubMed

Ly, Thuc Hue; Yun, Seok Joon; Thi, Quoc Huy; Zhao, Jiong

2017-07-25

Delamination of thin films from the supportive substrates is a critical issue within the thin film industry. The emergent two-dimensional, atomic layered materials, including transition metal dichalcogenides, are highly flexible; thus buckles and wrinkles can be easily generated and play vital roles in the corresponding physical properties. Here we introduce one kind of patterned buckling behavior caused by the delamination from a substrate initiated at the edges of the chemical vapor deposition synthesized monolayer transition metal dichalcogenides, led by thermal expansion mismatch. The atomic force microscopy and optical characterizations clearly showed the puckered structures associated with the strain, whereas the transmission electron microscopy revealed the special sawtooth-shaped edges, which break the geometrical symmetry for the buckling behavior of hexagonal samples. The condition of the edge delamination is in accordance with the fracture behavior of thin film interfaces. This edge delamination and buckling process is universal for most ultrathin two-dimensional materials, which requires more attention in various future applications.

Ultrananocrystalline diamond-coated nanoporous membranes support SK-N-SH neuroblastoma endothelial cell attachment.

PubMed

Yang, Kai-Hung; Nguyen, Alexander K; Goering, Peter L; Sumant, Anirudha V; Narayan, Roger J

2018-06-06

Ultrananocrystalline diamond (UNCD) has been demonstrated to have attractive features for biomedical applications and can be combined with nanoporous membranes for applications in drug delivery systems, biosensing, immunoisolation and single molecule analysis. In this study, free-standing nanoporous UNCD membranes with pore sizes of 100 or 400 nm were fabricated by directly depositing ultrathin UNCD films on nanoporous silicon nitride membranes and then etching away silicon nitride using reactive ion etching. Successful deposition of UNCD on the substrate with a novel process was confirmed with Raman spectroscopy, X-ray photoelectron spectroscopy, cross-section scanning electron microscopy (SEM) and transmission electron microscopy. Both sample types exhibited uniform geometry and maintained a clear hexagonal pore arrangement. Cellular attachment of SK-N-SH neuroblastoma endothelial cells was examined using confocal microscopy and SEM. Attachment of SK-N-SH cells onto UNCD membranes on both porous regions and solid surfaces was shown, indicating the potential use of UNCD membranes in biomedical applications such as biosensors and tissue engineering scaffolds.

Patterning of ultrathin polymethylmethacrylate films by in-situ photodirecting of the Marangoni flow

NASA Astrophysics Data System (ADS)

Elashnikov, Roman; Fitl, Premysl; Svorcik, Vaclav; Lyutakov, Oleksiy

2017-02-01

Laser heating and Marangoni flow result in the formation of surface structures with different geometries and shape on thin polymer films. By laser beam irradiation combined with a sample movement the solid polymethylmethacrylate (PMMA) films are heated and undergo phase transition which leads to a material flow. Since the laser beam has a non-linear distribution of energy, the PMMA film is heated inhomogeneously and a surface tension gradient in a lateral direction is introduced. During this procedure additional phenomena such as "reversible" or cyclic polymer flow also take place. The careful choice of experimental conditions enables the preparation of patterns with sophisticated geometries and with hierarchical pattern organization. Depending on initial PMMA film thickness and speed of the sample movement line arrays are created, which can subsequently be transformed into the crimped lines or system of circular holes. In addition, the introduction of a constant acceleration in the sample movement or a laser beam distortion enables the preparation of regularly crimped lines, ordered hexagonal holes or overlapped plates.

Ultralow-loss polaritons in isotopically pure boron nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giles, Alexander J.; Dai, Siyuan; Vurgaftman, Igor

Conventional optical components are limited to size scales much larger than the wavelength of light, as changes to the amplitude, phase and polarization of the electromagnetic fields are accrued gradually along an optical path. However, advances in nanophotonics have produced ultrathin, so-called ‘flat’ optical components that beget abrupt changes in these properties over distances significantly shorter than the free-space wavelength. Although high optical losses still plague many approaches, phonon polariton (PhP) materials have demonstrated long lifetimes for sub-diffractional modes in comparison to plasmon-polariton-based nanophotonics. We experimentally observe a threefold improvement in polariton lifetime through isotopic enrichment of hexagonal boron nitridemore » (hBN). Commensurate increases in the polariton propagation length are demonstrated via direct imaging of polaritonic standing waves by means of infrared nano-optics. Lastly, our results provide the foundation for a materials-growth-directed approach aimed at realizing the loss control necessary for the development of PhP-based nanophotonic devices.« less

Sns Moderator Poison Design and Experiment Validation of the Moderator Performance

NASA Astrophysics Data System (ADS)

Lu, W.; Iverson, E. B.; Ferguson, P. D.; Crabtree, J. A.; Gallmeier, F. X.; Remec, I.; Baxter, D. V.; Lavelle, C. M.

2009-08-01

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory reached 180 kW in August 2007, becoming the brightest pulsed neutron source in the world. At its full power of 1.4 MW, SNS will have thermal neutron fluxes approximately an order of magnitude greater than any existing pulsed spallation source. It thus brings a serious challenge to the lifetime of the moderator poison sheets. The SNS moderators are integrated with the inner reflector plug (IRP) at a cost of $2 million a piece. A replacement of the IRP presents a significant drawback to the facility due to the activation and the operation cost. Although there are many factors limiting the lifetime of the IRP, such as radiation damage to the structural material and helium production in beryllium, the limiting factor is the lifetime of the moderator poison sheets. The current operating target system of SNS was built with thick Gd poison sheets at a projected lifetime of 3 years. A recent design based on the MCNPX calculation proposed to replace the Gd poison sheets with even thicker Cd poison sheets, aiming to extend the poison sheet lifetime from 3 to 4 years accompanied by an approximate 5% gain of the moderator performance. An experiment was carried out to verify the calculated moderator performance at the Low Energy Neutron Source (LENS), Indiana University, where the spectra of two polyethylene moderators were measured. The moderators are Cd-decoupled and are poisoned with 0.8 mm Gd and 1.2 mm Cd, respectively. The preliminary analysis of the experiment data shows that the characteristics of the measured spectra of the Gd- and Cd-poisoned moderators agree well with what the calculation predicted. A better moderator performance is observed in the Cd-poisoned moderator. The measured ratio of Cd over Gd on the moderator performance is in a reasonable agreement with the calculation. Further investigation is underway for a better understanding of the difference between the experiment and the calculation.

Factors associated with online victimisation among Malaysian adolescents who use social networking sites: a cross-sectional study.

PubMed

Marret, Mary J; Choo, Wan Yuen

2017-06-30

To determine the prevalence of online interpersonal victimisation and its association with patterns of social networking site (SNS) use, offline victimisation, offline perpetration and parental conflict among Malaysian adolescents using SNS. A cross-sectional study of students from randomly selected public secondary schools in the state of Negeri Sembilan was conducted using an anonymous self-administered questionnaire. The questionnaire examined patterns of SNS use and included measures of online victimisation, online perpetration, offline victimisation and parental conflict. A response rate of 91% from a total of 1634 yielded a sample of 1487 students between 15 years and 16 years of age. Ninety-two per cent of respondents had used at least one SNS. More than half of SNS users (52.2%) reported experiences of online victimisation over the past 12 months. Boys were significantly more likely to experience online harassment compared with girls (52.2% vs 43.3%, p<0.001). There were no significant gender differences in experiences of unwanted sexual solicitation. Adolescents who engaged in perpetration behaviours online had almost six times higher odds of reporting frequent online victimisation compared with online behaviours involving personal disclosure. There was a significant dose-response relationship between engagement in multiple types of online behaviour and the risk of frequent online victimisation. Both online and offline perpetrations were associated with an increased risk of victimisation. Those who were victimised offline or experienced parental conflict were twice as likely to report online victimisation. Interventions to prevent online electronic aggression should target perpetration behaviour both online and offline. Youth should be equipped with skills in communication and decision-making in relationships that can be applied across a spectrum of contexts both online and offline. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The relationship between Facebook and Instagram appearance-focused activities and body image concerns in young women.

PubMed

Cohen, Rachel; Newton-John, Toby; Slater, Amy

2017-12-01

The present study aimed to identify the specific social networking sites (SNS) features that relate to body image concerns in young women. A total of 259 women aged 18-29years completed questionnaire measures of SNS use (Facebook and Instagram) and body image concerns. It was found that appearance-focused SNS use, rather than overall SNS use, was related to body image concerns in young women. Specifically, greater engagement in photo activities on Facebook, but not general Facebook use, was associated with greater thin-ideal internalisation and body surveillance. Similarly, following appearance-focused accounts on Instagram was associated with thin-ideal internalisation, body surveillance, and drive for thinness, whereas following appearance-neutral accounts was not associated with any body image outcomes. Implications for future SNS research, as well as for body image and disordered eating interventions for young women, are discussed. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Face-to-Face or Not-to-Face: A Technology Preference for Communication

PubMed Central

Darmawan, Bobby; Mohamed Ariffin, Mohd Yahya

2014-01-01

Abstract This study employed the Model of Technology Preference (MTP) to explain the relationship of the variables as the antecedents of behavioral intention to adopt a social networking site (SNS) for communication. Self-administered questionnaires were distributed to SNS account users using paper-based and web-based surveys that led to 514 valid responses. The data were analyzed using structural equation modeling (SEM). The results show that two out of three attributes of the attribute-based preference (ATRP) affect attitude-based preference (ATTP). The data support the hypotheses that perceived enjoyment and social presence are predictors of ATTP. In this study, the findings further indicated that ATTP has no relationship with the behavioral intention of using SNS, but it has a relationship with the attitude of using SNS. SNS development should provide features that ensure enjoyment and social presence for users to communicate instead of using the traditional face-to-face method of communication. PMID:25405782

Synthesis of hexagonal wurtzite Cu{sub 2}ZnSnS{sub 4} prisms by an ultrasound-assisted microwave solvothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Fei, E-mail: long.drf@gmail.com; Chi, Shangsen; Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083

Wurtzite Cu{sub 2}ZnSnS{sub 4} (CZTS) hexagonal prisms were synthesized by a simple ultrasound-microwave solvothermal method. The product was characterized by XRD, FESEM, EDS, TEM, Raman and UV–vis spectrometer. The hexagonal prisms were 0.5–2 μm wide and 5–12 μm long. The PVP played an important role in the formation of the CZTS hexagonal prisms. In addition, the ultrasound-assisted microwave process was helpful for synthesis of wurtzite rather than kesterite phase CZTS. A nucleation–dissolution–recrystallization mechanism was also proposed to explain the growth of the CZTS hexagonal prisms. - Graphical abstract: Wurtzite Cu{sub 2}ZnSnS{sub 4} hexagonal prisms were synthesized by ultrasound-microwave solvothermal method.more » The ultrasound-assisted microwave process and PVP were useful to the growth of CZTS. A nucleation–dissolution–recrystallization growth mechanism was also proposed. - Highlights: • Wurtzite Cu{sub 2}ZnSnS{sub 4} was prepared by ultrasound-assisted microwave solvothermal method. • The wurtzite CZTS hexagonal prisms are demonstrated a band gap of 1.49 eV. • Synergistic effect of ultrasound and microwave is helpful to prepare Wurtzite CZTS. • PVP plays an important role in the formation of the CZTS hexagonal prisms. • Nucleation–dissolution–recrystallization growth mechanism of the CZTS was proposed.« less

Ultrathin Lutetium Oxide Film as an Epitaxial Hole-Blocking Layer for Crystalline Bismuth Vanadate Water Splitting Photoanodes

DOE PAGES

Zhang, Wenrui; Yan, Danhua; Tong, Xiao; ...

2018-01-08

Here a novel ultrathin lutetium oxide (Lu 2O 3) interlayer is integrated with crystalline bismuth vanadate (BiVO4) thin film photoanodes to facilitate carrier transport through atomic-scale interface control. The epitaxial Lu 2O 32O 3

Nanoscale Surface Modification of Polycrystalline Tin Sulphide Films during Plasma Treatment

NASA Astrophysics Data System (ADS)

Zimin, S. P.; Gorlachev, E. S.; Dubov, G. A.; Amirov, I. I.; Naumov, V. V.; Gremenok, V. F.; Ivanov, V. A.; Seidi, H. G.

2013-05-01

In this paper, we present a comparative research of the nanoscale modification of the surface morphology of polycrystalline SnS films on glass substrates with two different preferred growth orientations processed in inductively coupled argon plasma. We report a new effect of polycrystalline SnS film surface smoothing during plasma treatment, which can be advantageous for the fabrication of multilayer solar cell devices with SnS absorption layers.

Analgesic effect of Facebook: Priming with online social networking may boost felt relatedness that buffers against physical pain.

PubMed

Ho, Liang-Chu; Wu, Wen-Hsiung; Chiou, Wen-Bin

2016-10-01

Social networking sites (SNSs) are extremely popular for providing users with a convenient platform for acquiring social connections and thereby feeling relatedness. Plenty of literature has shown that mental representations of social support can reduce the perception of physical pain. The current study tested whether thinking about SNS would interfere with users' perceptions of experimentally induced pain. Ninety-six undergraduate Facebook users were recruited to participate in a priming-based experiment. They were randomly assigned to one of the three study conditions (SNS prime, neutral prime, or no prime) via rating the aesthetics of logos. The results showed that participants exposed to SNS primes reported less pain of immersion in hot water than did both control groups (neutral- and no-prime). Felt relatedness mediated the link between SNS primes and diminished pain perceptions. This research provides the first demonstration that thinking about SNS can lower experienced physical pain among Facebook users. Online social networking may serve as an analgesic buffer against pain experience than previously thought. The SNS-enabled analgesia has far reaching implications for pain relief applications and the enhancement of well-being in human-interaction techniques. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Permissive Parenting, Deviant Peer Affiliations, and Delinquent Behavior in Adolescence: the Moderating Role of Sympathetic Nervous System Reactivity.

PubMed

Hinnant, J Benjamin; Erath, Stephen A; Tu, Kelly M; El-Sheikh, Mona

2016-08-01

The present study examined two measures of sympathetic nervous system (SNS) activity as moderators of the indirect path from permissive parenting to deviant peer affiliations to delinquency among a community sample of adolescents. Participants included 252 adolescents (M = 15.79 years; 53 % boys; 66 % European American, 34 % African American). A multi-method design was employed to address the research questions. Two indicators of SNS reactivity, skin conductance level reactivity (SCLR) and cardiac pre-ejection period reactivity (PEPR) were examined. SNS activity was measured during a baseline period and a problem-solving task (star-tracing); reactivity was computed as the difference between the task and baseline periods. Adolescents reported on permissive parenting, deviant peer affiliations, externalizing behaviors, and substance use (alcohol, marijuana). Analyses revealed indirect effects between permissive parenting and delinquency via affiliation with deviant peers. Additionally, links between permissive parenting to affiliation with deviant peers and affiliation with deviant peers to delinquency was moderated by SNS reactivity. Less SNS reactivity (less PEPR and/or less SCLR) were risk factors for externalizing problems and alcohol use. Findings highlight the moderating role of SNS reactivity in parenting and peer pathways that may contribute to adolescent delinquency and point to possibilities of targeted interventions for vulnerable youth.

Permissive Parenting, Deviant Peer Affiliations, and Delinquent Behavior in Adolescence: The Moderating Role of Sympathetic Nervous System Reactivity

PubMed Central

Hinnant, J. Benjamin; Erath, Stephen A.; Tu, Kelly M.; El-Sheikh, Mona

2015-01-01

The present study examined two measures of sympathetic nervous system (SNS) activity as moderators of the indirect path from permissive parenting to deviant peer affiliations to delinquency among a community sample of adolescents. Participants included 252 adolescents (M = 15.79 years; 53% boys; 66% European American, 34% African American). A multi-method design was employed to address the research questions. Two indicators of SNS reactivity, skin conductance level reactivity (SCLR) and cardiac pre-ejection period reactivity (PEPR) were examined. SNS activity was measured during a baseline period and a problem-solving task (star-tracing); reactivity was computed as the difference between the task and baseline periods. Adolescents reported on permissive parenting, deviant peer affiliations, externalizing behaviors, and substance use (alcohol, marijuana). Analyses revealed indirect effects between permissive parenting and delinquency via affiliation with deviant peers. Additionally, links between permissive parenting to affiliation with deviant peers and affiliation with deviant peers to delinquency was moderated by SNS reactivity. Less SNS reactivity (less PEPR and/or less SCLR) were risk factors for externalizing problems and alcohol use. Findings highlight the moderating role of SNS reactivity in parenting and peer pathways that may contribute to adolescent delinquency and point to possibilities of targeted interventions for vulnerable youth. PMID:26667026

Extrinsic pseudocapacitve Li-ion storage of SnS anode via lithiation-induced structural optimization on cycling

NASA Astrophysics Data System (ADS)

Lian, Qingwang; Zhou, Gang; Liu, Jiatu; Wu, Chen; Wei, Weifeng; Chen, Libao; Li, Chengchao

2017-10-01

Here, we report a new enhanced extrinsic pseudocapacitve Li-ion storage mechanism via lithiation-induced structural optimization strategy. The flower-like C@SnS and bulk SnS exhibit initial capacity decay and subsequent increase of capacity on cycling. After a long-term lithiation/delithiation process, flower-like C@SnS and bulk SnS exhibit improved rate performance and reversible capacity in comparison with those of initial state. Moreover, a high capacity of 530 mAh g-1 is still remained even after 1550 cycles at a high current density of 5.0 A g-1 for flower-like C@SnS after pre-lithiation of 350 cycles. According to the comprehensive analysis of structural evolution and electrochemical performance, it demonstrates that SnS electrodes experience crystal size reduction and further amorphization on cycling, which enhances the reversibility of conversion reaction for SnS, leading to increasing capacity. On the other hand, surface-dominated extrinsic pseudocapacitive contribution results in enhanced rate performance because electrodes expose a large fraction of Li+ sites on surface or near-surface region with structural optimization on cycling. This study reveals that extrinsic pseudocapacitance of SnS can be stimulated via lithiation-induced structural optimization, which gives rise to high-rate and long-lived performances.

Evidence of the paradoxical effect of social network support: A study among Filipino domestic workers in China.

PubMed

Mendoza, Norman B; Mordeno, Imelu G; Latkin, Carl A; Hall, Brian J

2017-09-01

Labor migrants are at an increased risk for poor mental health. Post-migration stressors contribute significantly to this risk. Social network supports are vitally important to protect health but little is known about the role of social network supports among labor migrants. The current study evaluated the role of migration stressors on poor mental health among Filipino female domestic workers (FDW) and whether family and friend social network support (SNS) modified this relationship. Data were collected from 261 FDWs in Macau, China from May to September 2013. Hierarchical multiple regression was conducted to test for direct and moderating effects of social networks on psychological distress. Post-migration stress was associated with increased anxiety, depression, somatization, and post-traumatic stress disorder symptoms. SNS from family was not associated with the four psychological symptoms nor did it modify the association between stress and these symptoms. SNS from friends was positively associated with these symptoms, and significantly moderated the relationship between stress and these symptoms. Counterintuitive to the known buffering effects of SNS, greater SNS was associated with greater psychological symptoms among FDWs exposed to post-migration stressors. The present findings suggest that reliance on SNS to cope with post-migration stressors may worsen psychological distress. Copyright © 2017. Published by Elsevier B.V.

Role of the speech-language pathologist: augmentative and alternative communication for acute care patients with severe communication impairments.

PubMed

Vento-Wilson, Margaret T; McGuire, Anthony; Ostergren, Jennifer A

2015-01-01

Severe communication deficits occur frequently in acute care. Augmentative and alternative communication (AAC) may improve patient-nurse communication, yet it remains underutilized. The objective of this study was to assess the impact of training student nurses (SNs) in acute and critical care on the use of AAC with regard to confidence levels and likelihood of implementation of AAC by SNs in acute care. Training in AAC techniques was provided to SNs. A pretraining and posttraining assessment was completed along with follow-up surveys conducted after the SNs had an opportunity to use AAC. A 6-fold increase in confidence (P < .01) was reported by the SNs after AAC training, as was an approximately 3-fold increase in likelihood of use (P < .01). The reliable yes/no was the most reported AAC technique (34.7% of the students). Providing SNs with AAC tools accompanied by brief training increases their confidence in the use of AAC and the likelihood that they will use them. Inclusion of AAC education in nursing curricula and nursing orientations could be an important step in risk reduction among patients with severe communication disorders. Further study is needed of the relationship between training student nurses in the use of AAC as a way to change practice and improve communication outcomes.

A comparative analysis of anorexia nervosa groups on Facebook.

PubMed

Teufel, Martin; Hofer, Eva; Junne, Florian; Sauer, Helene; Zipfel, Stephan; Giel, Katrin Elisabeth

2013-12-01

To analyze the content and culture of anorexia nervosa (AN)-related communication on the current major social network site (SNS) Facebook. We searched for groups and sites related to AN on Facebook by means of a faux profile of a young female. Identified groups/sites were analyzed with respect to (1) category (education, self-help, professional help, pro-ana, anti pro-ana), (2) activity, (3) motivational aspects (prose, pictures), and (4) social support. Numerous relevant groups were found in all categories except that professional help was almost nonexistent. Pro-ana groups were found to be the most active, best organized, and offered the highest levels of social support. Prose motivation was distinctly offered in all categories. Motivation with pictures was particularly evident in pro-ana groups. The most functional motivation was found in self-help groups. SNS appears to be a relevant way for young females suffering from AN to communicate and exchange disease and health-related ideas. Caregivers, researchers, and institutions in the field of eating disorders should be aware of the existence, possibilities, dysfunctions, and influence of SNS. Whether SNS can help persons with AN to get therapeutic assistance as well as whether it can be integrated into psychotherapeutic strategies should be examined in future studies.

Social network site addiction - an overview.

PubMed

Andreassen, Cecilie Schou; Pallesen, Ståle

2014-01-01

Research into frequent, excessive, and compulsive social network activity has increased the last years, in which terms such as "social network site addiction" and "Facebook addiction" have been used interchangeably. The aim of this review is to offer more knowledge and better understanding of social network site addiction (SNS-addiction) among researchers as well as clinicians by presenting a narrative overview of the research field in terms of definition, measurement, antecedents, consequences, and treatment as well as recommendations for future research efforts. Seven different measures of SNS-addiction have been developed, although they have to a very little extent been validated against each other. The small number of studies conducted so far on this topic suggests that SNS-addiction is associated with health-related, academic, and interpersonal problems/issues. However such studies have relied on a simple cross-sectional study design. It is therefore hard to draw any conclusions about potential causality and long-term effects at this point, beyond hypothetical speculations. Empirical studies suggest that SNS-addiction is caused by dispositional factors (e.g., personality, needs, self-esteem), although relevant explanatory socio-cultural and behavioral reinforcement factors remain to be empirically explored. No well-documented treatment for SNS-addiction exists, but knowledge gained from Internet addiction treatment approaches might be transferable to SNS-addiction. Overall, the research on this topic is in its infancy, and as such the SNS-addiction construct needs further conceptual and empirical exploration. There is a great demand for studies using careful longitudinal designs and studies which include objective measures of both behavior and health based on broad representative samples.

Friends' Alcohol-Related Social Networking Site Activity Predicts Escalations in Adolescent Drinking: Mediation by Peer Norms.

PubMed

Nesi, Jacqueline; Rothenberg, W Andrew; Hussong, Andrea M; Jackson, Kristina M

2017-06-01

Adolescents' increased use of social networking sites (SNS) coincides with a developmental period of heightened risk for alcohol use initiation. However, little is known regarding associations between adolescents' SNS use and drinking initiation nor the mechanisms of this association. This study examined longitudinal associations among adolescents' exposure to friends' alcohol-related SNS postings, alcohol-favorable peer injunctive norms, and initiation of drinking behaviors. Participants were 658 high-school students who reported on posting of alcohol-related SNS content by self and friends, alcohol-related injunctive norms, and other developmental risk factors for alcohol use at two time points, 1 year apart. Participants also reported on initiation of three drinking behaviors: consuming a full drink, becoming drunk, and heavy episodic drinking (three or more drinks per occasion). Probit regression analyses were used to predict initiation of drinking behaviors from exposure to alcohol-related SNS content. Path analyses examined mediation of this association by peer injunctive norms. Exposure to friends' alcohol-related SNS content predicted adolescents' initiation of drinking and heavy episodic drinking 1 year later, controlling for demographic and known developmental risk factors for alcohol use (i.e., parental monitoring and peer orientation). In addition, alcohol-favorable peer injunctive norms statistically mediated the relationship between alcohol-related SNS exposure and each drinking milestone. Results suggest that social media plays a unique role in contributing to peer influence processes surrounding alcohol use and highlight the need for future investigative and preventive efforts to account for adolescents' changing social environments. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

New Professionalism Challenges in Medical Training: An Exploration of Social Networking

PubMed Central

Kesselheim, Jennifer C.; Batra, Maneesh; Belmonte, Frank; Boland, Kimberly A.; McGregor, Robert S.

2014-01-01

Background Innovative online technology can enhance the practice of medicine, yet it also may be a forum for unprofessional behavior. Objective We surveyed program directors regarding their perceptions and experiences with residents' use of social networking sites (SNS). Methods In September 2011, we sent an online survey to program directors and associate program directors of pediatrics residency programs within the United States who are members of the Association of Pediatric Program Directors. Results A total of 162 program directors or associate program directors (representing 50% of residency programs) responded to the survey. One-third of respondents are “very familiar” with SNS and 23% use them “daily or often.” Most respondents (70%) rated “friending” peers as “completely appropriate,” whereas only 1% of respondents rated “friending” current or past patients as “completely appropriate.” More than one half of respondents believe inappropriate behavior on SNS is “somewhat” or “very” prevalent, and 91% are “somewhat” or “very” concerned that the prevalence of inappropriate behavior on SNS may increase. The most commonly reported problematic online activity was posting inappropriate comments about the workplace. Posting of inappropriate comments about self, patients, and staff also was observed. Residency programs commonly educate trainees about SNS during intern orientation (45%), or using written guidelines (29%) and ad hoc remediation (16%). Conclusions As educators teach trainees principles of online professionalism, appropriate use of SNS needs to be included in the training process. Curricular efforts may be hindered by some program directors' lack of familiarity with SNS. PMID:24701318

Shared responsibility: school nurses' experience of collaborating in school-based interprofessional teams.

PubMed

Reuterswärd, Marina; Hylander, Ingrid

2017-06-01

The Swedish Education Act (2011) mandated a new combination of services to boost students' physical health, their mental health and special education through interprofessional pupil health and well-being (PH) teams. For Swedish school nurses, providing these services presents new challenges. To describe how Swedish school nurses experience their work and collaboration within the interprofessional PH teams. Twenty-five school nurses (SNs) were interviewed in five focus groups. Content analysis was used to examine the data and to explore SNs' workplace characteristics by using the components of the sense of coherence (SOC) framework. SNs' experiences of work and collaboration within PH teams can be described using three domains: the expectations of others regarding SNs' roles, SNs' contributions to pupils' health and well-being, and collaboration among SNs within PH teams. The results indicate a discrepancy between SNs' own experiences of their contribution and their experiences of other professionals' expectations regarding those contributions. Some duties were perceived as expected, comprehensible, manageable and meaningful, while other duties - though expected - were perceived as less meaningful, taking time away from school-related matters. Other duties that were not explicitly expected - promoting general health and creating safety zones for pupils, teachers and parents, for example - were nonetheless perceived as meaningful. Collaboration within PH teams was considered meaningful, comprehensible and manageable only if the objectives of the team meetings were clear, if other professionals were available and if professional roles on the team were clearly communicated. The SNs reported a lack of clarity regarding their role in PH and its implementation in schools, indicating that professionals in PH teams need to discuss collaboration so as to find their niche given the new conditions. SOC theory emerged as a useful framework for discussing concrete work-related factors in the school environment. © 2016 Nordic College of Caring Science.

A cost-effective nanoporous ultrathin film electrode based on nanoporous gold/IrO2 composite for proton exchange membrane water electrolysis

NASA Astrophysics Data System (ADS)

Zeng, Yachao; Guo, Xiaoqian; Shao, Zhigang; Yu, Hongmei; Song, Wei; Wang, Zhiqiang; Zhang, Hongjie; Yi, Baolian

2017-02-01

A cost-effective nanoporous ultrathin film (NPUF) electrode based on nanoporous gold (NPG)/IrO2 composite has been constructed for proton exchange membrane (PEM) water electrolysis. The electrode was fabricated by integrating IrO2 nanoparticles into NPG through a facile dealloying and thermal decomposition method. The NPUF electrode is featured in its 3D interconnected nanoporosity and ultrathin thickness. The nanoporous ultrathin architecture is binder-free and beneficial for improving electrochemical active surface area, enhancing mass transport and facilitating releasing of oxygen produced during water electrolysis. Serving as anode, a single cell performance of 1.728 V (@ 2 A cm-2) has been achieved by NPUF electrode with a loading of IrO2 and Au at 86.43 and 100.0 μg cm-2 respectively, the electrolysis voltage is 58 mV lower than that of conventional electrode with an Ir loading an order of magnitude higher. The electrolysis voltage kept relatively constant up to 300 h (@250 mA cm-2) during the course of durability test, manifesting that NPUF electrode is promising for gas evolution.

Interfacial structure and electrical properties of ultrathin HfO2 dielectric films on Si substrates by surface sol-gel method

NASA Astrophysics Data System (ADS)

Gong, You-Pin; Li, Ai-Dong; Qian, Xu; Zhao, Chao; Wu, Di

2009-01-01

Ultrathin HfO2 films with about ~3 nm thickness were deposited on n-type (1 0 0) silicon substrates using hafnium chloride (HfCl4) source by the surface sol-gel method and post-deposition annealing (PDA). The interfacial structure and electrical properties of ultrathin HfO2 films were investigated. The HfO2 films show amorphous structures and smooth surface morphologies with a very thin interfacial oxide layer of ~0.5 nm and small surface roughness (~0.45 nm). The 500 °C PDA treatment forms stronger Hf-O bonds, leading to passivated traps, and the interfacial layer is mainly Hf silicate (HfxSiyOz). Equivalent oxide thickness of around 0.84 nm of HfO2/Si has been obtained with a leakage current density of 0.7 A cm-2 at Vfb + 1 V after 500 °C PDA. It was found that the current conduction mechanism of HfO2/Si varied from Schottky-Richardson emission to Fowler-Nordheim tunnelling at an applied higher positive voltage due to the activated partial traps remaining in the ultrathin HfO2 films.

Kinetics of Plasma Viremia and Soluble Nonstructural Protein 1 Concentrations in Dengue: Differential Effects According to Serotype and Immune Status

PubMed Central

Duyen, Huynh T. L.; Ngoc, Tran V.; Hang, Vu T. T.; Kieu, Nguyen T. T.; Young, Paul R.; Farrar, Jeremy J.; Simmons, Cameron P.; Wolbers, Marcel; Wills, Bridget A.

2011-01-01

We describe the magnitude and kinetics of plasma viremia and nonstructural protein 1 (sNS1) levels in sequential samples from 167 children with acute dengue, enrolled early in a community study in Vietnam. All children recovered fully, and only 5 required hospitalization. Among those with dengue virus type 1 (DENV-1), plasma viremia was significantly greater in primary (49) than secondary (44) infections and took longer to resolve. In primary DENV-2 and 3 infections, viremia was significantly lower than among primary DENV-1 infections. Concentrations of sNS1 were significantly higher for DENV-1 than for DENV-2 after adjusting for viremia, with marked differences in the kinetic profiles between primary and secondary infections. Secondary infection and higher viremia were independent predictors of more severe thrombocytopenia, and higher viremia was associated with a small increase in hemoconcentration. Our findings identify clear serotype and immune-status related effects on the dynamics of dengue viremia and sNS1 responses, together with associations with important clinical parameters. PMID:21335562

Intrinsic Ferroelasticity and/or Multiferroicity in Two-Dimensional Phosphorene and Phosphorene Analogues.

PubMed

Wu, Menghao; Zeng, Xiao Cheng

2016-05-11

Phosphorene and phosphorene analogues such as SnS and SnSe monolayers are promising nanoelectronic materials with desired bandgap, high carrier mobility, and anisotropic structures. Here, we show first-principles calculation evidence that these monolayers are potentially the long-sought two-dimensional (2D) materials that can combine electronic transistor characteristic with nonvolatile memory readable/writeable capability at ambient condition. Specifically, phosphorene is predicted to be a 2D intrinsic ferroelastic material with ultrahigh reversible strain, whereas SnS, SnSe, GeS, and GeSe monolayers are multiferroic with coupled ferroelectricity and ferroelasticity. Moreover, their low-switching barriers render room-temperature nonvolatile memory accessible, and their notable structural anisotropy enables ferroelastic or ferroelectric switching readily readable via electrical, thermal, optical, mechanical, or even spintronic detection upon the swapping of the zigzag and armchair direction. In addition, it is predicted that the GeS and GeSe monolayers as well as bulk SnS and SnSe can maintain their ferroelasticity and ferroelectricity (anti-ferroelectricity) beyond the room temperature, suggesting high potential for practical device application.

Field-dependent magnetization of BiFeO 3 in ultrathin La 0.7Sr 0.3MnO 3/BiFeO 3 superlattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzsimmons, Michael R.; Jia, Quanxi X.; Singh, Surendra

2015-12-02

We report the observation of field-induced magnetization of BiFeO 3 (BFO) in an ultrathin La 0.7Sr 0.3MnO 3 (LSMO)/BFO superlattice using polarized neutron reflectivity (PNR). The depth dependent structure and magnetic characterization of subnano layer thick (thickness ~ 0.7 nm each) LSMO/BFO hetrostructure is carried out using X-ray reflectivity and PNR techniques. Our PNR results indicate parallel alignment of magnetization as well as enhancement in magnetic moment across LSMO/BFO interfaces. The study showed an increase in average magnetization on increasing applied magnetic field at 10K. As a result, we observed a saturation magnetization of 110 ± 15 kA/m (~0.8 μmore » B/Fe) for ultrathin BFO layer (~2 unit cell) sandwiched between ultrathin LSMO layers (~ 2 unit cell).« less

A Ga2O3 underlayer as an isomorphic template for ultrathin hematite films toward efficient photoelectrochemical water splitting.

PubMed

Hisatomi, Takashi; Brillet, Jérémie; Cornuz, Maurin; Le Formal, Florian; Tétreault, Nicolas; Sivula, Kevin; Grätzel, Michael

2012-01-01

Hematite photoanodes for photoelectrochemical (PEC) water splitting are often fabricated as extremely-thin films to minimize charge recombination because of the short diffusion lengths of photoexcited carriers. However, poor crystallinity caused by structural interaction with a substrate negates the potential of ultrathin hematite photoanodes. This study demonstrates that ultrathin Ga2O3 underlayers, which were deposited on conducting substrates prior to hematite layers by atomic layer deposition, served as an isomorphic (corundum-type) structural template for ultrathin hematite and improved the photocurrent onset of PEC water splitting by 0.2 V. The benefit from Ga2O3 underlayers was most pronounced when the thickness of the underlayer was approximately 2 nm. Thinner underlayers did not work effectively as a template presumably because of insufficient crystallinity of the underlayer, while thicker ones diminished the PEC performance of hematite because the underlayer prevented electron injection from hematite to a conductive substrate due to the large conduction band offset. The enhancement of PEC performance by a Ga2O3 underlayer was more significant for thinner hematite layers owing to greater margins for improving the crystallinity of ultrathin hematite. It was confirmed that a Ga2O3 underlayer was applicable to a rough conducting substrate loaded with Sb-doped SnO2 nanoparticles, improving the photocurrent by a factor of 1.4. Accordingly, a Ga2O3 underlayer could push forward the development of host-guest-type nanocomposites consisting of highly-rough substrates and extremely-thin hematite absorbers.

One-step solvothermal synthesis of carnation flower-like SnS2 as superior electrodes for supercapacitor applications

NASA Astrophysics Data System (ADS)

Mishra, Rajneesh Kumar; Baek, Geun Woo; Kim, Kyuwon; Kwon, Hyuck-In; Jin, Sung Hun

2017-12-01

We report the synthesis of carnation flower-like SnS2 (CF-SnS2) via a one-step solvothermal method for potential application as supercapacitor electrodes in energy storage devices. The structural and morphological properties of CF-SnS2 were characterized by X-ray diffraction, Raman analysis, and field-emission scanning and transmission electron microscopies. X-ray photoelectron spectroscopy and scanning tunneling electron microscopy with color mapping verified the distribution of Sn and S, and depicted the successful formation of SnS2. Electrochemical studies were performed to explore the supercapacitive nature of CF-SnS2. Supercapacitors with CF-SnS2 electrodes delivered excellent cyclic voltammetry performances, superior gravimetric specific capacitances, and high power densities. The evaluated specific capacitance and power density reached ∼524.5 F/g and 12.3 W/kg, respectively, at a current density of 0.08 A/g, and ∼215.9 F/g and 61.4 W/kg, respectively, at a current density of 0.38 A/g. These values are at least two times higher than those previously reported. The long-term cyclic stability was also tested to demonstrate the endurance of the CF-SnS2-based supercapacitor, with a 66% rate retention and galvanostatic charge/discharge reversibility. These electrochemical findings indicate that CF-SnS2 is a promising candidate for electrode materials in supercapacitor applications.

Spatially controlled doping of two-dimensional SnS2 through intercalation for electronics

NASA Astrophysics Data System (ADS)

Gong, Yongji; Yuan, Hongtao; Wu, Chun-Lan; Tang, Peizhe; Yang, Shi-Ze; Yang, Ankun; Li, Guodong; Liu, Bofei; van de Groep, Jorik; Brongersma, Mark L.; Chisholm, Matthew F.; Zhang, Shou-Cheng; Zhou, Wu; Cui, Yi

2018-04-01

Doped semiconductors are the most important building elements for modern electronic devices1. In silicon-based integrated circuits, facile and controllable fabrication and integration of these materials can be realized without introducing a high-resistance interface2,3. Besides, the emergence of two-dimensional (2D) materials enables the realization of atomically thin integrated circuits4-9. However, the 2D nature of these materials precludes the use of traditional ion implantation techniques for carrier doping and further hinders device development10. Here, we demonstrate a solvent-based intercalation method to achieve p-type, n-type and degenerately doped semiconductors in the same parent material at the atomically thin limit. In contrast to naturally grown n-type S-vacancy SnS2, Cu intercalated bilayer SnS2 obtained by this technique displays a hole field-effect mobility of 40 cm2 V-1 s-1, and the obtained Co-SnS2 exhibits a metal-like behaviour with sheet resistance comparable to that of few-layer graphene5. Combining this intercalation technique with lithography, an atomically seamless p-n-metal junction could be further realized with precise size and spatial control, which makes in-plane heterostructures practically applicable for integrated devices and other 2D materials. Therefore, the presented intercalation method can open a new avenue connecting the previously disparate worlds of integrated circuits and atomically thin materials.

Signatures of Induced Superconductivity in NbTi Contacted InAs Quantum Wells

NASA Astrophysics Data System (ADS)

McFadden, Anthony; Shabani, Javad; Shojaei, Borzoyeh; Lee, Joon Sue; Palmstrøm, Chris

We have studied electrical transport through InAs quantum wells grown by MBE with unannealed superconducting NbTi contacts deposited ex-situ and patterned by optical photolithography. Characterization of the InAs 2DEG's without superconducting contacts yields typical mobilities greater than 100,000 cm2/Vs at a density of 4e11 cm-2. NbTi-InAs-NbTi (SNS) and NbTi-InAs (SN) devices with dimensions greater than 1 µm are fabricated using optical lithography. Although the dimensions of the fabricated SNS devices are too large to observe a supercurrent, signatures of superconductivity induced in the InAs are present. We observe two superconducting critical temperatures: one of the NbTi leads (Tc~8K), and a second (Tc <4.5K) attributed to superconductivity induced in the InAs channel. dI/dV vs V spectroscopy on SNS junctions below the second critical temperature shows a conductance maximum at zero applied voltage while conductance minima appear at finite bias voltage which is attributed to the presence of an induced superconducting gap in the InAs quantum well. This work has been supported by Microsoft research.

Ultrathin Composite Polymeric Membranes for CO2 /N2 Separation with Minimum Thickness and High CO2 Permeance.

PubMed

Benito, Javier; Sánchez-Laínez, Javier; Zornoza, Beatriz; Martín, Santiago; Carta, Mariolino; Malpass-Evans, Richard; Téllez, Carlos; McKeown, Neil B; Coronas, Joaquín; Gascón, Ignacio

2017-10-23

The use of ultrathin films as selective layers in composite membranes offers significant advantages in gas separation for increasing productivity while reducing the membrane size and energy costs. In this contribution, composite membranes have been obtained by the successive deposition of approximately 1 nm thick monolayers of a polymer of intrinsic microporosity (PIM) on top of dense membranes of the ultra-permeable poly[1-(trimethylsilyl)-1-propyne] (PTMSP). The ultrathin PIM films (30 nm in thickness) demonstrate CO 2 permeance up to seven times higher than dense PIM membranes using only 0.04 % of the mass of PIM without a significant decrease in CO 2 /N 2 selectivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

PubMed Central

Pathi, Prathap; Peer, Akshit; Biswas, Rana

2017-01-01

Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm) and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm) and is slightly lower (by ~5%) at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm) silicon and just 1%–2% for thicker (>100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping. PMID:28336851

Nano-photonic structures for light trapping in ultra-thin crystalline silicon solar cells

DOE PAGES

Pathi, Prathap; Peer, Akshit; Biswas, Rana

2017-01-13

Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a densemore » mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm) and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm) and is slightly lower (by ~5%) at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm) silicon and just 1%–2% for thicker (>100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. Furthermore, this architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.« less

Nano-photonic structures for light trapping in ultra-thin crystalline silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pathi, Prathap; Peer, Akshit; Biswas, Rana

Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a densemore » mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm) and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm) and is slightly lower (by ~5%) at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm) silicon and just 1%–2% for thicker (>100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. Furthermore, this architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.« less

Migraine-related healthcare resource use and costs for subjects prescribed fixed-dose combination sumatriptan/naproxen sodium vs. single-entity oral triptans in a managed care population in the USA.

PubMed

Runken, M Chris; Goodwin, Bridgett; Shah, Manan; Eaddy, Michael; D'Souza, Anna; Bowers, Brian; Bell, Christopher F

2015-02-01

Randomized clinical trials have demonstrated that the efficacy of a fixed-dose single-tablet combination containing sumatriptan and naproxen sodium (S/NS) was greater than either of its individual components. Simplifying drug regimens (e.g., via a fixed-dose combination) has been shown to improve "real-world" outcomes by reducing pill burden and treatment regimen complexity, improving adherence, and reducing healthcare resource use and associated costs; however, no studies assessing such outcomes have been conducted to date for the acute treatment of migraine. To assess migraine-related healthcare resource use and associated costs for subjects prescribed S/NS vs. subjects prescribed single-entity oral triptans (SOTs) within a managed care population in the USA. In this retrospective analysis of administrative claims data from July 1, 2008 to December 31, 2009 (IMS LifeLink), subjects meeting the following criteria were selected: one or more pharmacy claim(s) for either S/NS or SOT (index date), aged 18-64 years; at least one migraine diagnosis, and continuous enrollment in the 6 months prior to and post the index date. The study population was subsequently stratified for two analyses: triptan-naïve (triptan naïve in the 6-month period prior to the index date) and triptan-switch (triptan user in the 6-month period prior to the index date and switching to another triptan). Subjects prescribed S/NS were propensity-score matched with subjects prescribed SOT (triptan-naïve analysis: 1:3; triptan-switch analysis: 1:1) to assess differences in healthcare resource use and associated costs (2009 US$) between the S/NS and SOT groups. Results from the triptan-naïve and triptan-switch analyses suggest that subjects prescribed S/NS are likely to have similar healthcare resource use patterns as those either newly initiated on an SOT or switching SOTs, as measured by migraine medication use, migraine-related healthcare resource use, and all-cause healthcare resource use. One exception was the observed increased use of opioids in the SOT group compared with the S/NS group (change in mean number of tablets pre-index vs. post-index, S/NS vs. SOT; triptan-naïve analysis: 8.6 vs.18.3, p = 0.045; triptan-switch analysis: -8.2 vs. 17.7; p = 0.120). Total costs from the triptan-naïve analysis indicated that the S/NS group had lower migraine-related (US$744 vs. US$820; p = 0.067) and all-cause healthcare costs (US$4,391 vs. US$4,870; p = 0.040) when compared with the SOT group, driven by savings in medical costs (migraine-related: US$252 vs. US$380; p = 0.001; all-cause: US$3,023 vs. US$3,599; p = 0.014). However, no significant differences were observed for total costs from the triptan-switch analysis (migraine-related healthcare costs, S/NS vs. SOT: US$1,159 vs. US$1,117; p = 0.929; all-cause healthcare costs: US$5,128 vs. US$4,788; p = 0.381). Study results suggest similar healthcare resource use patterns and associated costs when comparing S/NS and SOT across a triptan-naïve and triptan-experienced population. While the current study focuses on direct medical costs, future studies should extend beyond such a perspective to explore functional status, productivity, and health-related quality of life and satisfaction, attributes not captured in administrative claims data, but nonetheless important treatment goals.

APCVD hexagonal boron nitride thin films for passive near-junction thermal management of electronics

NASA Astrophysics Data System (ADS)

KC, Pratik; Rai, Amit; Ashton, Taylor S.; Moore, Arden L.

2017-12-01

The ability of graphene to serve as an ultrathin heat spreader has been previously demonstrated with impressive results. However, graphene is electrically conductive, making its use in contact with electronic devices problematic from a reliability and integration perspective. As an alternative, hexagonal boron nitride (h-BN) is a similarly structured material with large in-plane thermal conductivity but which possesses a wide band gap, thereby giving it potential to be utilized for directing contact, near-junction thermal management of electronics without shorting or the need for an insulating intermediate layer. In this work, the viability of using large area, continuous h-BN thin films as direct contact, near-junction heat spreaders for electronic devices is experimentally evaluated. Thin films of h-BN several square millimeters in size were synthesized via an atmospheric pressure chemical vapor deposition (APCVD) method that is both simple and scalable. These were subsequently transferred onto a microfabricated test device that simulated a multigate transistor while also allowing for measurements of the device temperature at various locations via precision resistance thermometry. Results showed that these large-area h-BN films with thicknesses of 77-125 nm are indeed capable of significantly lowering microdevice temperatures, with the best sample showing the presence of the h-BN thin film reduced the effective thermal resistance by 15.9% ± 4.6% compared to a bare microdevice at the same power density. Finally, finite element simulations of these experiments were utilized to estimate the thermal conductivity of the h-BN thin films and identify means by which further heat spreading performance gains could be attained.

Transverse beam stability measurement and analysis for the SNS accumulator ring

DOE PAGES

Xie, Zaipeng; Deibele, Craig; Schulte, Michael J.; ...

2015-07-01

In a Field-programmable gate array (FPGA) based transverse feedback damper system we implemented in the Spallation Neutron Source (SNS) accumulator ring with the intention to stabilize the electron-proton (e-p) instability in a frequency range from 1 MHz to 300 MHz. The transverse damper could also be used as a diagnostic tool by measuring the beam transfer function (BTF). An analysis of the BTF measurement provides the stability diagram for the production beam at SNS. Our paper describes the feedback damper system and its set-up as the BTF diagnostic tool. Experimental BTF results are presented and beam stability analysis is performedmore » based on the BTF measurements for the SNS accumulator ring.« less

Rapid amperometric detection of trace metals by inhibition of an ultrathin polypyrrole-based glucose biosensor.

PubMed

Ayenimo, Joseph G; Adeloju, Samuel B

2016-02-01

A sensitive and reliable inhibitive amperometric glucose biosensor is described for rapid trace metal determination. The biosensor utilises a conductive ultrathin (55 nm thick) polypyrrole (PPy) film for entrapment of glucose oxidase (GOx) to permit rapid inhibition of GOx activity in the ultrathin film upon exposure to trace metals, resulting in reduced glucose amperometric response. The biosensor demonstrates a relatively fast response time of 20s and does not require incubation. Furthermore, a complete recovery of GOx activity in the ultrathin PPy-GOx biosensor is quickly achieved by washing in 2mM EDTA for only 10s. The minimum detectable concentrations achieved with the biosensor for Hg(2+), Cu(2+), Pb(2+) and Cd(2+) by inhibitive amperometric detection are 0.48, 1.5, 1.6 and 4.0 µM, respectively. Also, suitable linear concentration ranges were achieved from 0.48-3.3 µM for Hg(2+), 1.5-10 µM for Cu(2+), 1.6-7.7 µM for Pb(2+) and 4-26 µM for Cd(2+). The use of Dixon and Cornish-Bowden plots revealed that the suppressive effects observed with Hg(2+) and Cu(2+) were via non-competitive inhibition, while those of Pb(2+) and Cd(2+) were due to mixed and competitive inhibition. The stronger inhibition exhibited by the trace metals on GOx activity in the ultrathin PPy-GOx film was also confirmed by the low inhibition constant obtained from this analysis. The biosensor was successfully applied to the determination of trace metals in tap water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

2D-2D stacking of graphene-like g-C3N4/Ultrathin Bi4O5Br2 with matched energy band structure towards antibiotic removal

NASA Astrophysics Data System (ADS)

Ji, Mengxia; Di, Jun; Ge, Yuping; Xia, Jiexiang; Li, Huaming

2017-08-01

A novel visible-light-driven 2D-2D graphene-like g-C3N4/ultrathin Bi4O5Br2 photocatalyst was prepared via a facile solvothermal method in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br) for the first time. FT-IR, XPS and TEM analysis results demonstrated the successful introduction of the 2D graphene-like g-C3N4 material to the Bi4O5Br2 system. DRS and BET analysis results indicated the existence of the g-C3N4 could lead to the broaden absorption edge and larger surface area of the ultrathin Bi4O5Br2 nanosheets. The electrochemical analysis implied a fast transfer of the interfacial electrons and low recombination rate of photogenerated charge carriers in g-C3N4/Bi4O5Br2, which could be assigned to the sufficient and tight contact between ultrathin Bi4O5Br2 and graphene-like g-C3N4. The quinolone antibiotic ciprofloxacin (CIP) was chosen as the target pollutant to evaluate the photocatalytic performance of the as-prepared samples under visible light irradiation. 1 wt% g-C3N4/Bi4O5Br2 composite exhibited the highest photocatalytic degradation performance among all of the as-prepared photocatalysts. The enhancement of photocatalytic activity was attributed to the maximum contact between graphene-like g-C3N4 and ultrathin Bi4O5Br2 material with matched energy band structure, which enable the efficient charge seperation. A possible photocatalytic mechanism also was proposed.

Spatially controlled doping of two-dimensional SnS 2 through intercalation for electronics

DOE PAGES

Gong, Yongji; Yuan, Hongtao; Wu, Chun-Lan; ...

2018-02-26

Doped semiconductors are the most important building elements for modern electronic devices. In silicon-based integrated circuits, facile and controllable fabrication and integration of these materials can be realized without introducing a high-resistance interface. Besides, the emergence of two-dimensional (2D) materials enables the realization of atomically thin integrated circuits. However, the 2D nature of these materials precludes the use of traditional ion implantation techniques for carrier doping and further hinders device development10. Here, we demonstrate a solvent-based intercalation method to achieve p-type, n-type and degenerately doped semiconductors in the same parent material at the atomically thin limit. In contrast to naturallymore » grown n-type S-vacancy SnS 2, Cu intercalated bilayer SnS 2 obtained by this technique displays a hole field-effect mobility of ~40 cm 2 V -1 s -1, and the obtained Co-SnS 2 exhibits a metal-like behaviour with sheet resistance comparable to that of few-layer graphene. Combining this intercalation technique with lithography, an atomically seamless p–n–metal junction could be further realized with precise size and spatial control, which makes in-plane heterostructures practically applicable for integrated devices and other 2D materials. Therefore, the presented intercalation method can open a new avenue connecting the previously disparate worlds of integrated circuits and atomically thin materials.« less

Spatially controlled doping of two-dimensional SnS 2 through intercalation for electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Yongji; Yuan, Hongtao; Wu, Chun-Lan

Doped semiconductors are the most important building elements for modern electronic devices. In silicon-based integrated circuits, facile and controllable fabrication and integration of these materials can be realized without introducing a high-resistance interface. Besides, the emergence of two-dimensional (2D) materials enables the realization of atomically thin integrated circuits. However, the 2D nature of these materials precludes the use of traditional ion implantation techniques for carrier doping and further hinders device development10. Here, we demonstrate a solvent-based intercalation method to achieve p-type, n-type and degenerately doped semiconductors in the same parent material at the atomically thin limit. In contrast to naturallymore » grown n-type S-vacancy SnS 2, Cu intercalated bilayer SnS 2 obtained by this technique displays a hole field-effect mobility of ~40 cm 2 V -1 s -1, and the obtained Co-SnS 2 exhibits a metal-like behaviour with sheet resistance comparable to that of few-layer graphene. Combining this intercalation technique with lithography, an atomically seamless p–n–metal junction could be further realized with precise size and spatial control, which makes in-plane heterostructures practically applicable for integrated devices and other 2D materials. Therefore, the presented intercalation method can open a new avenue connecting the previously disparate worlds of integrated circuits and atomically thin materials.« less

The sentinel lymph node spread determines quantitatively melanoma seeding to non-sentinel lymph nodes and survival.

PubMed

Ulmer, Anja; Dietz, Klaus; Werner-Klein, Melanie; Häfner, Hans-Martin; Schulz, Claudia; Renner, Philipp; Weber, Florian; Breuninger, Helmut; Röcken, Martin; Garbe, Claus; Fierlbeck, Gerhard; Klein, Christoph A

2018-03-01

Complete lymph node dissection (CLND) after a positive sentinel node (SN) biopsy provides important prognostic information in melanoma patients but has been questioned for therapeutic use recently. We explored whether quantification of the tumour spread to SNs may replace histopathology of non-sentinel nodes (NSNs) for staging purposes. We quantified melanoma spread in SNs and NSNs in 128 patients undergoing CLND for a positive SN. In addition to routine histopathology, one-half of each of all 1496 SNs and NSNs was disaggregated into a single cell suspension and stained immunocytochemically to determine the number of melanoma cells per 10 6 lymph node cells, i.e. the disseminated cancer cell density (DCCD). We uncovered melanoma spread to NSNs in the majority of patients; however, the tumour load and the proportion of positive nodes were significantly lower in NSNs than in SNs. The relation between SN and NSN spread could be described by a mathematical function with DCCD NSN  = DCCD SN c /10 1 - c (c = 0.69; 95% confidence interval [CI]: 0.62-0.76). At a median follow-up of 67 months, multivariable Cox regression analyses revealed that DCCD SN (p = 0.02; HR 1.34, 95% CI: 1.05-1.71) and the total number of pathologically positive nodes (p = 0.02; HR 1.53, 95% CI: 1.07-2.22) were significant risk factors after controlling for age, gender, thickness of melanoma and ulceration status. A prognostic model based on DCCD SN and melanoma thickness predicted outcome as accurately as a model including pathological information of both SNs and NSNs. The assessment of DCCD SN renders CLND for staging purposes unnecessary. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risk factors for testicular cancer--differences between pure non-seminoma and mixed seminoma/non-seminoma?

PubMed

Aschim, E L; Haugen, T B; Tretli, S; Daltveit, A K; Grotmol, T

2006-08-01

The origin of testicular germ cell cancer (TGCC) is believed to be carcinoma in situ cells developed in utero. Clinically, TGCCs are divided into two major histological groups, seminomas and non-seminomas, where the latter group includes non-seminomatous TGCCs with seminomatous components (mixed S/NS TGCC). Recent studies, however, have suggested that non-seminomas and mixed S/NS TGCCs could have certain differences in aetiology, and in this study the TGCCs were divided into three, rather than the conventional two histological groups. A large case-control study was undertaken on data on all live-born boys registered in the Medical Birth Registry of Norway during the period 1967-1998 (n=961 396). Among these were 1087 TGCC cases registered in the Cancer Registry of Norway until February 2004. We found several risk factors for TGCC, including low parity, low gestational age, epilepsy and retained placenta. Several of the variables studied seemed to be risk factors for specific histological groups, e.g. parity 0 vs. 2 and low gestational age being associated with increased risk of non-seminomas, but not of mixed S/NS TGCC, and low maternal age being associated with increased risk of mixed S/NS TGCC, but not of non-seminomatous TGCC. Therefore, our results might suggest that non-seminomas and mixed S/NS TGCCs have partially different risk factors, whose associations may be obscured by combining these two histological groups. The histological groups were not significantly different, however. Most of our findings on risk factors for TGCC are in agreement with at least some previous studies. An unexplainable exception is low birth weight being associated with reduced risk of TGCC in our study.

High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi2O2Se

NASA Astrophysics Data System (ADS)

Wu, Jinxiong; Yuan, Hongtao; Meng, Mengmeng; Chen, Cheng; Sun, Yan; Chen, Zhuoyu; Dang, Wenhui; Tan, Congwei; Liu, Yujing; Yin, Jianbo; Zhou, Yubing; Huang, Shaoyun; Xu, H. Q.; Cui, Yi; Hwang, Harold Y.; Liu, Zhongfan; Chen, Yulin; Yan, Binghai; Peng, Hailin

2017-07-01

High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ˜0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm2 V-1 s-1 is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO3-SrTiO3 interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm2 V-1 s-1), large current on/off ratios (>106) and near-ideal subthreshold swing values (˜65 mV dec-1) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.

The predictive value of methylene blue dye as a single technique in breast cancer sentinel node biopsy: a study from Dharmais Cancer Hospital.

PubMed

Brahma, Bayu; Putri, Rizky Ifandriani; Karsono, Ramadhan; Andinata, Bob; Gautama, Walta; Sari, Lenny; Haryono, Samuel J

2017-02-07

Axillary lymph node dissection (ALND) has been the standard treatment of breast cancer axillary staging in Indonesia. The limited facilities of radioisotope tracer and isosulfan or patent blue dye (PBD) have been the major obstacles to perform sentinel node biopsy (SNB) in our country. We studied the application of 1% methylene blue dye (MBD) alone for SNB to overcome the problem. This prospective study enrolled 108 patients with suspicious malignant lesions or breast cancer stages I-III. SNB was performed using 2-5 cc of 1% MBD and proceeded with ALND. The histopathology results of sentinel nodes (SNs) were compared with axillary lymph nodes (ALNs) for diagnostic value assessments. There were 96 patients with invasive carcinoma from July 2012 to September 2014 who were included in the final analysis. The median age was 50 (25-69) years, and the median pathological tumor size was 3 cm (1-10). Identification rate of SNs was 91.7%, and the median number of the identified SNs was 2 (1-8). Sentinel node metastasis was found in 53.4% cases and 89.4% of them were macrometastases. The negative predictive value (NPV) of SNs to predict axillary metastasis was 90% (95% CI, 81-99%). There were no anaphylactic reactions, but we found 2 cases with skin necrosis. The application of 1% MBD as a single technique in breast cancer SNB has favorable identification rates and predictive values. It can be used for axillary staging, but nevertheless the technique should be applied with attention to the tumor size and grade to avoid false negative results.

Sex-related online behaviors and adolescents' body and sexual self-perceptions.

PubMed

Doornwaard, Suzan M; Bickham, David S; Rich, Michael; Vanwesenbeeck, Ine; van den Eijnden, Regina J J M; ter Bogt, Tom F M

2014-12-01

This study investigated: (1) the prevalence and development of 2 receptive (sexually explicit Internet material [SEIM] use and sexual information seeking) and 2 interactive (cybersex and general social networking site [SNS] use) online behaviors in adolescence; (2) whether development of these behaviors predict adolescents' body and sexual self-perceptions; and (3) whether parental strategies regarding adolescents' Internet use reduce engagement in sex-related online behaviors. Four-wave longitudinal data among 1132 seventh- to 10th-grade Dutch adolescents (mean age at wave 1: 13.95 years; 52.7% boys) were collected. Developmental trajectories of sex-related online behaviors were estimated by using latent growth curve modeling. Self-perception outcomes at wave 4 and parental strategies predicting online behaviors were investigated by adding regression paths to growth models. Boys occasionally and increasingly used SEIM. Patterns for girls' SEIM use and boys' and girls' sexual information seeking and cybersex were consistently low. SNS use, however, was a common, daily activity for both. Higher initial levels and/or faster increases in sex-related online behaviors generally predicted less physical self-esteem (girls' SNS use only), more body surveillance, and less satisfaction with sexual experience. Private Internet access and less parental rule setting regarding Internet use predicted greater engagement in sex-related online behaviors. Although most sex-related online behaviors are not widespread among youth, adolescents who engage in such behaviors are at increased risk for developing negative body and sexual self-perceptions. Particular attention should be paid to adolescents' SNS use because this behavior is most popular and may, through its interactive characteristics, elicit more critical self-evaluations. Prevention efforts should focus on parents' role in reducing risky sex-related online behaviors. Copyright © 2014 by the American Academy of Pediatrics.

Facile Synthesis of Ultrathin Nickel-Cobalt Phosphate 2D Nanosheets with Enhanced Electrocatalytic Activity for Glucose Oxidation.

PubMed

Shu, Yun; Li, Bing; Chen, Jingyuan; Xu, Qin; Pang, Huan; Hu, Xiaoya

2018-01-24

Two-dimensional (2D) ultrathin nickel-cobalt phosphate nanosheets were synthesized using a simple one-step hydrothermal method. The morphology and structure of nanomaterials synthesized under different Ni/Co ratios were investigated by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Moreover, the influence of nanomaterials' structure on the electrochemical performance for glucose oxidation was investigated. It is found that the thinnest nickel-cobalt phosphate nanosheets synthesized with a Ni/Co ratio of 2:5 showed the best electrocatalytic activity for glucose oxidation. Also, the ultrathin nickel-cobalt phosphate nanosheet was used as an electrode material to construct a nonenzymatic electrochemical glucose sensor. The sensor showed a wide linear range (2-4470 μM) and a low detection limit (0.4 μM) with a high sensitivity of 302.99 μA·mM -1 ·cm -2 . Furthermore, the application of the as-prepared sensor in detection of glucose in human serum was successfully demonstrated. These superior performances prove that ultrathin 2D nickel-cobalt phosphate nanosheets are promising materials in the field of electrochemical sensing.

Ultrathin solution-processed single crystals of thiophene-phenylene co-oligomers for organic field-effect devices

NASA Astrophysics Data System (ADS)

Glushkova, Anastasia V.; Poimanova, Elena Yu.; Bruevich, Vladimir V.; Luponosov, Yuriy N.; Ponomarenko, Sergei A.; Paraschuk, Dmitry Yu.

2017-08-01

Thiophene-phenylene co-oligomers (TPCO) single crystals are promising materials for organic light-emitting devices, e.g., light-emitting transistors (OLETs), due to their ability to combine high luminescence and efficient charge transport. However, optical confinement in platy single crystals strongly decreases light emission from their top surface degrading the device performance. To avoid optical waveguiding, single crystals thinner than 100 nm would be beneficial. Herein, we report on solution-processed ultrathin single crystals of TPCO and study their charge transport properties. As materials we used 1,4-bis(5'-hexyl-2,2'-bithiophene-5-yl)benzene (DH-TTPTT) and 1,4-bis(5'-decyl-2,2'-bithiophene-5-yl)benzene (DD-TTPTT). The ultrathin single crystals were studied by optical polarization, atomic-force, and transmission electron microscopies, and as active layers in organic field effect transistors (OFET). The OFET hole mobility was increased tenfold for the oligomer with longer alkyl substituents (DD-TTPTT) reaching 0.2 cm2/Vs. Our studies of crystal growth indicate that if the substrate is wetted, it has no significant effect on the crystal growth. We conclude that solution-processed ultrathin TPCO single crystals are a promising platform for organic optoelectronic field-effect devices.

Modularized Parallel Neutron Instrument Simulation on the TeraGrid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Meili; Cobb, John W; Hagen, Mark E

2007-01-01

In order to build a bridge between the TeraGrid (TG), a national scale cyberinfrastructure resource, and neutron science, the Neutron Science TeraGrid Gateway (NSTG) is focused on introducing productive HPC usage to the neutron science community, primarily the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Monte Carlo simulations are used as a powerful tool for instrument design and optimization at SNS. One of the successful efforts of a collaboration team composed of NSTG HPC experts and SNS instrument scientists is the development of a software facility named PSoNI, Parallelizing Simulations of Neutron Instruments. Parallelizing the traditional serialmore » instrument simulation on TeraGrid resources, PSoNI quickly computes full instrument simulation at sufficient statistical levels in instrument de-sign. Upon SNS successful commissioning, to the end of 2007, three out of five commissioned instruments in SNS target station will be available for initial users. Advanced instrument study, proposal feasibility evalua-tion, and experiment planning are on the immediate schedule of SNS, which pose further requirements such as flexibility and high runtime efficiency on fast instrument simulation. PSoNI has been redesigned to meet the new challenges and a preliminary version is developed on TeraGrid. This paper explores the motivation and goals of the new design, and the improved software structure. Further, it describes the realized new fea-tures seen from MPI parallelized McStas running high resolution design simulations of the SEQUOIA and BSS instruments at SNS. A discussion regarding future work, which is targeted to do fast simulation for automated experiment adjustment and comparing models to data in analysis, is also presented.« less

Short and long sympathetic-sensory feedback loops in white fat

PubMed Central

Ryu, Vitaly

2014-01-01

We previously demonstrated white adipose tissue (WAT) innervation using the established WAT retrograde sympathetic nervous system (SNS)-specific transneuronal viral tract tracer pseudorabies virus (PRV152) and showed its role in the control of lipolysis. Conversely, we demonstrated WAT sensory innervation using the established anterograde sensory system (SS)-specific transneuronal viral tracer, the H129 strain of herpes simplex virus-1, with sensory nerves showing responsiveness with increases in WAT SNS drive. Several brain areas were part of the SNS outflow to and SS inflow from WAT between these studies suggesting SNS-SS feedback loops. Therefore, we injected both PRV152 and H129 into inguinal WAT (IWAT) of Siberian hamsters. Animals were perfused on days 5 and 6 postinoculation after H129 and PRV152 injections, respectively, and brains, spinal cords, sympathetic, and dorsal root ganglia (DRG) were processed for immunohistochemical detection of each virus across the neuroaxis. The presence of H129+PRV152-colocalized neurons (∼50%) in the spinal segments innervating IWAT suggested short SNS-SS loops with significant coinfections (>60%) in discrete brain regions, signifying long SNS-SS loops. Notably, the most highly populated sites with the double-infected neurons were the medial part of medial preoptic nucleus, medial preoptic area, hypothalamic paraventricular nucleus, lateral hypothalamus, periaqueductal gray, oral part of the pontine reticular nucleus, and the nucleus of the solitary tract. Collectively, these results strongly indicate the neuroanatomical reality of the central SNS-SS feedback loops with short loops in the spinal cord and long loops in the brain, both likely involved in the control of lipolysis or other WAT pad-specific functions. PMID:24717676

Social Networking Sites, Depression, and Anxiety: A Systematic Review

PubMed Central

Kern, Margaret L; Rickard, Nikki S

2016-01-01

Background Social networking sites (SNSs) have become a pervasive part of modern culture, which may also affect mental health. Objective The aim of this systematic review was to identify and summarize research examining depression and anxiety in the context of SNSs. It also aimed to identify studies that complement the assessment of mental illness with measures of well-being and examine moderators and mediators that add to the complexity of this environment. Methods A multidatabase search was performed. Papers published between January 2005 and June 2016 relevant to mental illness (depression and anxiety only) were extracted and reviewed. Results Positive interactions, social support, and social connectedness on SNSs were consistently related to lower levels of depression and anxiety, whereas negative interaction and social comparisons on SNSs were related to higher levels of depression and anxiety. SNS use related to less loneliness and greater self-esteem and life satisfaction. Findings were mixed for frequency of SNS use and number of SNS friends. Different patterns in the way individuals with depression and individuals with social anxiety engage with SNSs are beginning to emerge. Conclusions The systematic review revealed many mixed findings between depression, anxiety, and SNS use. Methodology has predominantly focused on self-report cross-sectional approaches; future research will benefit from leveraging real-time SNS data over time. The evidence suggests that SNS use correlates with mental illness and well-being; however, whether this effect is beneficial or detrimental depends at least partly on the quality of social factors in the SNS environment. Understanding these relationships will lead to better utilization of SNSs in their potential to positively influence mental health. PMID:27881357

Social Networking Sites, Depression, and Anxiety: A Systematic Review.

PubMed

Seabrook, Elizabeth M; Kern, Margaret L; Rickard, Nikki S

2016-11-23

Social networking sites (SNSs) have become a pervasive part of modern culture, which may also affect mental health. The aim of this systematic review was to identify and summarize research examining depression and anxiety in the context of SNSs. It also aimed to identify studies that complement the assessment of mental illness with measures of well-being and examine moderators and mediators that add to the complexity of this environment. A multidatabase search was performed. Papers published between January 2005 and June 2016 relevant to mental illness (depression and anxiety only) were extracted and reviewed. Positive interactions, social support, and social connectedness on SNSs were consistently related to lower levels of depression and anxiety, whereas negative interaction and social comparisons on SNSs were related to higher levels of depression and anxiety. SNS use related to less loneliness and greater self-esteem and life satisfaction. Findings were mixed for frequency of SNS use and number of SNS friends. Different patterns in the way individuals with depression and individuals with social anxiety engage with SNSs are beginning to emerge. The systematic review revealed many mixed findings between depression, anxiety, and SNS use. Methodology has predominantly focused on self-report cross-sectional approaches; future research will benefit from leveraging real-time SNS data over time. The evidence suggests that SNS use correlates with mental illness and well-being; however, whether this effect is beneficial or detrimental depends at least partly on the quality of social factors in the SNS environment. Understanding these relationships will lead to better utilization of SNSs in their potential to positively influence mental health. ©Elizabeth M Seabrook, Margaret L Kern, Nikki S Rickard. Originally published in JMIR Mental Health (http://mental.jmir.org), 23.11.2016.

Fabrication of silicon-on-diamond substrate with an ultrathin SiO2 bonding layer

NASA Astrophysics Data System (ADS)

Nagata, Masahiro; Shirahama, Ryouya; Duangchan, Sethavut; Baba, Akiyoshi

2018-06-01

We proposed and demonstrated a sputter etching method to prepare both a flat surface (root-mean-square surface roughness of approximately 0.2–0.3 nm) and an ultrathin SiO2 bonding layer at an accuracy of approximately 5 nm in thickness to fabricate a silicon-on-diamond substrate (SOD). We also investigated a plasma activation method on a SiO2 surface using various gases. We found that O2 plasma activation is more suitable for the bonding between SiO2 and Si than N2 or Ar plasma activation. We speculate that the concentration of hydroxyl groups on the SiO2 surface was increased by O2 plasma activation. We fabricated the SOD substrate with an ultrathin (15 nm in thickness) SiO2 bonding layer using the sputter etching and O2 plasma activation methods.

Who You Gonna Call? Responding to a Medical Emergency with the Strategic National Stockpile

DTIC Science & Technology

2004-06-01

pharmaceuticals. The logistical burden on the local and state responders who receive, dispense, and distribute the SNS is considerable. The time and...bulk drugs in the SNS are repackaged on- site , the labeling machines that accompany each of the push packs can be programmed to provide the required...burden on local responders , who already will be facing a significant task in dispensing the SNS materiel to a (potentially) large affected population

Social and parasocial relationships on social network sites and their differential relationships with users' psychological well-being.

PubMed

Baek, Young Min; Bae, Young; Jang, Hyunmi

2013-07-01

With the advent of social network sites (SNSs), people can efficiently maintain preexisting social relationships and make online friendships without offline encounters. While such technological features of SNSs hold a variety of potential for individual and collective benefits, some scholars warn that use of SNSs might lead to socially negative consequences, such as social isolation, erosion of social cohesion, or SNS addiction. This study distinguishes types of SNS relationships, and investigates their relationships with social isolation, interpersonal trust, and SNS addiction. We classify SNS relationships into two types: (a) social relationships based on reciprocity between a user and his/her friends, and (b) parasocial relationships in which an ordinary user is aware of activities of a celebrity (e.g., famous actors, athletes, and others) but not vice versa. Based on achievements in studies of media effect and social psychology, we constructed a set of hypotheses, and tested them using a subsample of SNS users drawn from representative survey data in South Korea. We found that dependency on parasocial relationships is positively related with loneliness but negatively correlated with interpersonal distrust, while dependency on social relationship is negatively correlated with loneliness but positively related with trust. However, more dependency on both social and parasocial relationships are positively related with SNS addiction. Implications based on findings are also discussed.

The independent relationship between trouble controlling Facebook use, time spent on the site and distress.

PubMed

Muench, Fredrick; Hayes, Marie; Kuerbis, Alexis; Shao, Sijing

2015-09-01

There is an emerging literature base on the relationship between maladaptive traits and "addiction" to social networking sites. These studies have operationalized addiction as either spending excessive amounts of time on social networking sites (SNS) or trouble controlling SNS use, but have not assessed the unique contribution of each of these constructs on outcomes in the same models. Moreover, these studies have exclusively been conducted with younger people rather than a heterogeneous sample. This study examined the independent relationship of a brief Facebook addiction scale, time spent on Facebook, and Facebook checking on positive and negative social domains, while controlling for self-esteem and social desirability. Participants were recruited using e-mail, SNS posts and through Amazon's MTurk system. The sample included 489 respondents ages from 18 to approximately 70, who completed a 10-15 minute survey. Results indicate that neither time spent on Facebook nor Facebook checking was significantly associated with either self-esteem, fear of negative social evaluation or social comparison, while SNS addiction symptoms were each independently associated with Facebook usage. Neither time spent on Facebook nor SNS addiction symptoms were associated with positive social relationships. Overall results suggest that time on SNS and trouble controlling use should be considered independent constructs and that interventions should target underlying loss of control as the primary intervention target above ego syntonic time spent on the site.

Brief review of emerging photovoltaic absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakutayev, Andriy

Photovoltaic solar cells have recently made significant commercial progress and are on track toward meeting more than 1% of global energy demand. However, further research is needed on photovoltaic technologies that face no scalability constraints in generating more than 10% of the world's electricity. This 2017 article briefly reviews emerging photovoltaic absorber materials, focusing on research progress over the past 2-3 years. Particular emphasis is given to emerging solar cell absorbers -- for example, SnS, Sb 2Se 3, Cu 2SnS 3, and CuSbSe 2 -- related to established solar cell technologies such as CdTe, Cu(In,Ga)Se 2, and CH 3NH 3PbImore » 3. Lastly, the general publication and performance trends are discussed, and the promising future research directions are pointed out.« less

Brief review of emerging photovoltaic absorbers

DOE PAGES

Zakutayev, Andriy

2017-02-08

Photovoltaic solar cells have recently made significant commercial progress and are on track toward meeting more than 1% of global energy demand. However, further research is needed on photovoltaic technologies that face no scalability constraints in generating more than 10% of the world's electricity. This 2017 article briefly reviews emerging photovoltaic absorber materials, focusing on research progress over the past 2-3 years. Particular emphasis is given to emerging solar cell absorbers -- for example, SnS, Sb 2Se 3, Cu 2SnS 3, and CuSbSe 2 -- related to established solar cell technologies such as CdTe, Cu(In,Ga)Se 2, and CH 3NH 3PbImore » 3. Lastly, the general publication and performance trends are discussed, and the promising future research directions are pointed out.« less

Deceptive Intentions: Can Cues to Deception Be Measured before a Lie Is Even Stated?

PubMed Central

Ströfer, Sabine; Noordzij, Matthijs L.; Ufkes, Elze G.; Giebels, Ellen

2015-01-01

Can deceitful intentions be discriminated from truthful ones? Previous work consistently demonstrated that deceiving others is accompanied by nervousness/stress and cognitive load. Both are related to increased sympathetic nervous system (SNS) activity. We hypothesized that SNS activity already rises during intentions to lie and, consequently, cues to deception can be detected before stating an actual lie. In two experiments, controlling for prospective memory, we monitored SNS activity during lying, truth telling, and truth telling with the aim of lying at a later instance. Electrodermal activity (EDA) was used as an indicator of SNS. EDA was highest during lying, and compared to the truth condition, EDA was also raised during the intention to deceive. Moreover, the switch from truth telling toward lying in the intention condition evoked higher EDA than switching toward non-deception related tasks in the lie or truth condition. These results provide first empirical evidence that increased SNS activity related to deception can be monitored before a lie is stated. This implies that cues to deception are already present during the mere intention to lie. PMID:26018573

College Students' Drinking and Posting About Alcohol: Forwarding a Model of Motivations, Behaviors, and Consequences.

PubMed

Thompson, Charee M; Romo, Lynsey K

2016-06-01

College drinking continues to remain a public health problem that has been exacerbated by alcohol-related posts on social networking sites (SNSs). Although existing research has linked alcohol consumption, alcohol posts, and adverse consequences to one another, comprehensive explanations for these associations have been largely unexplored. Thus, we reasoned that students' personal motivations (i.e., espousing an alcohol identity, needing entertainment, and adhering to social norms) influence their behaviors (i.e., alcohol consumption and alcohol-related posting on SNSs), which can lead to alcohol problems. Using structural equation modeling, we analyzed data from 364 undergraduate students and found general support for our model. In particular, espousing an alcohol identity predicted alcohol consumption and alcohol-related SNS posting, needing entertainment predicted alcohol consumption but not alcohol-related SNS posting, and adhering to social norms predicted alcohol-related SNS posting but not alcohol consumption. In turn, alcohol consumption and alcohol-related SNS posting predicted alcohol problems. It is surprising that alcohol-related SNS posting was a stronger predictor of alcohol problems than alcohol consumption. We discuss the findings within their applied applications for college student health.

Is the igeneration a 'we' generation? Social networking use among 9- to 13-year-olds and belonging.

PubMed

Quinn, Sally; Oldmeadow, Julian A

2013-03-01

Research suggests that online communication is associated with increased closeness to friends and friendship quality. Children under 13 years of age are increasingly using social networking sites (SNSs), but research with this younger age group is scarce. This study examined the relationship between SNS use and feelings of belonging among children aged 9-13 years. A self-report questionnaire was administered to 443 children (48.98% boys), asking about their SNS use and their sense of belonging to their friendship group. SNS users reported a stronger sense of belonging to their friendship group than non-users, but this was found only among older boys. Furthermore, among boy SNS users, a positive linear relationship was found between the intensity of usage and feelings of belonging. No significant relationships were found for girls. These findings suggest that boys who use these sites are gaining friendship benefits over and above those boys who are non-users or low-intensity users. Longitudinal studies should investigate the causal relationships between SNS use and social effects within this age group. © 2012 The British Psychological Society.

Impact of Social Networking Sites on Children in Military Families.

PubMed

McGuire, Austen B; Steele, Ric G

2016-09-01

Youth in military families experience a relatively unique set of stressors that can put them at risk for numerous psychological and behavior problems. Thus, there is a need to identify potential mechanisms by which children can gain resiliency against these stressors. One potential mechanism that has yet to be empirically studied with military youth is social networking sites (SNSs). SNSs have gained significant popularity among society, especially youth. Given the significance of these communication tools in youths' lives, it is important to analyze how SNS use may affect military youth and their ability to cope with common military life stressors. The current review examines the potential positive and negative consequences associated with SNS use in coping with three common stressors of youth in military families: parent deployment, frequent relocation, and having a family member with a psychological or physical disability. By drawing from SNS and military literature, we predict that SNS use can be a positive tool for helping children in military families to cope with stressors. However, certain SNS behaviors can potentially result in more negative outcomes. Recommendations for future research are also discussed.

Online social networking and the experience of cyber-bullying.

PubMed

O'Dea, Bridianne; Campbell, Andrew

2012-01-01

Online social networking sites (SNS) are popular social tools used amongst adolescents and account for much of their daily internet activity. Recently, these sites have presented opportunities for youth to experience cyber-bullying. Often resulting in psychological distress, cyber-bullying is a common experience for many young people. Continual use of SNS signifies the importance of examining its links to cyber-bullying. This study examined the relationship between online social networking and the experience of cyber-bullying. A total of 400 participants (Mage=14.31 years) completed an online survey which examined the perceived definitions and frequency of cyber-bullying. Users of SNS reported significantly higher frequencies of stranger contact compared to non-users. Spearman's rho correlations determined no significant relationship between daily time on SNS and the frequency of stranger contact. This suggests that ownership of a SNS profile may be a stronger predictor of some cyber-bullying experiences compared to time spent on these sites. Findings encourage continued research on the nature of internet activities used by young adolescents and the possible exposure to online victimization.

A model "go-kit" for use at Strategic National Stockpile Points of Dispensing.

PubMed

May, Larissa; Cote, Timothy; Hardeman, Bernard; Gonzalez, Gabriela R; Adams, Sherry B; Blair, Roderick K; Pane, Gregg

2007-01-01

The Strategic National Stockpile (SNS) is a national repository of pharmaceuticals and other medical supplies forseeably needed during a medical disaster. In the event of SNS deployment, state and local public health authorities must be prepared to receive, distribute, and dispense the materials. We propose a cache of supplies, termed the "POD go-kit," prepared in advance and locally available prior to the establishment of Points of Dispensing (POD) for SNS material. Characteristics of the preassembled go-kit are its multiplicity of use, ease of storage and transportation, minimal redundancy with SNS material, and packaging in a manner consistent with POD function. The POD go-kit is assembled into 4 separate "subkits": administrative supplies, patient routing supplies, dispensing supplies, and POD staff protection supplies. Incorporating existing practices from the SNS Listserv, this article itemizes the contents of the POD go-kit and its subkits and provides a rationale for its packaging. The Division of Strategic National Stockpile (DSNS) has not certified the proposed "POD go-kit" as a standardized POD go-kit.

Development of a researcher codebook for use in evaluating social networking site profiles.

PubMed

Moreno, Megan A; Egan, Katie G; Brockman, Libby

2011-07-01

Social networking sites (SNSs) are immensely popular and allow for the display of personal information, including references to health behaviors. Evaluating displayed content on an SNS for research purposes requires a systematic approach and a precise data collection instrument. The purpose of this article is to describe one approach to the development of a research codebook so that others may develop and test their own codebooks for use in SNS research. Our SNS research codebook began on the basis of health behavior theory and clinical criteria. Key elements in the codebook developmental process included an iterative team approach and an emphasis on confidentiality. Codebook successes include consistently high inter-rater reliability. Challenges include time investment in coder training and SNS server changes. We hope that this article will provide detailed information about one systematic approach to codebook development so that other researchers may use this structure to develop and test their own codebooks for use in SNS research. Copyright © 2011 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Direct peroral cholangioscopy using an ultrathin endoscope: making technique easier.

PubMed

Sola-Vera, Javier; Uceda, Francisco; Cuesta, Rubén; Vázquez, Narcís

2014-01-01

Cholangioscopy is a useful tool for the study and treatment of biliary pathology. Ultrathin upper endoscopes allow direct peroral cholangioscopy (DPC) but have some drawbacks. The aim of the study was to evaluate the success rate of DPC with an ultrathin endoscope using a balloon catheter to reach the biliary confluence. Prospective observational study. An ultrathin endoscope (Olympus XP180N, outer diameter 5.5 mm, working channel 2 mm) was used. To access the biliary tree, free-hand technique was used. To reach the biliary confluence an intraductal balloon catheter (Olympus B5-2Q diameter 1.9 mm) and a 0.025 inch guide wire was used. In all cases sphincterotomy and/or sphincteroplasty was performed. The success rate was defined as the percentage of cases in which the biliary confluence could be reached with the ultrathin endoscope. Fifteen patients (8 men/7 women) were included. Mean age was 77.7 + or - 10.8 years (range 45-91). The indications for cholangioscopy were suspected bile duct stones (n = 9), electrohydraulic lithotripsy for the treatment of difficult choledocholithiasis (n = 5) and evaluation of biliary stricture (n = 1). Access to the bile duct was achieved in 14/15 cases (93.3%). Biliary confluence was reached in 13/15 cases (86.7%). One complication was observed in one patient (oxigen desaturation). DPC with an ultrathin endoscope can be done with the free-hand technique. Intraductal balloon-guided DPC allows full examination of the common bile duct in most cases.

Habitat-related specialization of lateral-line system morphology in a habitat-generalist and a habitat-specialist New Zealand eleotrid.

PubMed

Vanderpham, J P; Nakagawa, S; Senior, A M; Closs, G P

2016-04-01

An investigation of intraspecific habitat-related patterns of variation in oculoscapular lateral-line superficial neuromasts (SN) identified a decrease in the ratio of total SNs to pores, and a trend towards decreased asymmetry in SNs in the habitat-generalist common bully Gobiomorphus cotidianus from fluvial habitats compared to lacustrine habitats, suggesting habitat-related phenotypic variability. A greater ratio of pores to SNs, as well as less variation in the total number and asymmetry of SNs observed in the fluvial habitat-specialist redfin bully Gobiomorphus huttoni may provide further evidence of variations in the oculoscapular lateral-line morphology of fluvial habitat G. cotidianus individuals serving as adaptations to more turbulent environments. © 2016 The Fisheries Society of the British Isles.

Identity Confusion and Materialism Mediate the Relationship Between Excessive Social Network Site Usage and Online Compulsive Buying.

PubMed

Sharif, Saeed Pahlevan; Khanekharab, Jasmine

2017-08-01

This study investigates the mediating role of identity confusion and materialism in the relationship between social networking site (SNS) excessive usage and online compulsive buying among young adults. A total of 501 SNS users aged 17 to 23 years (M = 19.68, SD = 1.65) completed an online survey questionnaire. A serial multiple mediator model was developed and hypotheses were tested using structural equation modeling. The results showed that excessive young adult SNS users had a higher tendency toward compulsive buying online. This was partly because they experienced higher identity confusion and developed higher levels of materialism. Targeted psychological interventions seeking to gradually increase identity clarity to buffer the detrimental effects of SNS usage and identity confusion in young adults are suggested.

α-Amylase as a reliable and convenient measure of sympathetic activity: don't start salivating just yet!

PubMed

Bosch, Jos A; Veerman, Enno C I; de Geus, Eco J; Proctor, Gordon B

2011-05-01

Recent years have seen a growing interest in salivary α-amylase (sAA) as a non-invasive marker for sympathetic nervous system (SNS) activity. Saliva offers many advantages as a biomarker fluid and sAA is one of its most plentiful components. sAA is a digestive enzyme that breaks down starch, which provides a simple means of quantification by measuring its enzymatic activity. This commentary will address a number of common misconceptions and methodological issues that surround the use of sAA as a marker of SNS activity and limit its utility in biobehavioral research. The usefulness of sAA as an SNS marker is undermined by the fact that the parasympathetic nerves also play a significant role in sAA release. Local parasympathetic nerves regulate sAA activity via: (1) α-amylase release from glands that are solely or mainly parasympathetically innervated; (2) via synergistic sympathetic-parasympathetic effects on protein secretion (known as 'augmented secretion'); and (3) via effects on salivary flow rate. Regarding methodology, we discuss why it is problematic: (1) to ignore the contribution of salivary flow rate; (2) to use absorbent materials for saliva collection, and; (3) to stimulate saliva secretion by chewing. While these methodological problems can be addressed by using standardized and timed collection of unstimulated saliva, the physiological regulation of sAA secretion presents less resolvable issues. We conclude that at present there is insufficient support for the use and interpretation of sAA activity as a valid and reliable measure of SNS activity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Applications of Nanostructured Graphene in Optoelectronics as Transparent Conductors and Photodetectors

NASA Astrophysics Data System (ADS)

Xu, Guowei

Graphene, a single layer of carbon atoms arranged in a hexagonal lattice, has unique properties of high carrier mobility, high optical transmittance, chemical inertness and flexibility, making it attractive for electronic and optoelectronic applications, such as graphene transistors, ultrahigh capacitors, transparent conductors (TCs), photodetectors. This work explores novel schemes of nanostructured graphene for optoelectronic applications including advanced TCs and photodetectors. In nanophotonic graphene nanohole arrays patterned using nanoimprinting lithography (NIL), highly efficient chemical doping was achieved on the hole edges. This provides a unique scheme for improving both optical transmittance and electrical conductivity of graphene-based TCs. In plasmonic graphene, Ag nanoparticles were decorated on graphene using thermally assisted self-assembly and NIL. Much enhanced conductivity by a factor of 2-4 was achieved through electron doping in graphene from Ag nanoparticles. More importantly, surface plasmonic effect has been incorporated into plasmonic graphene as advanced TCs with light trapping, which is critical to ultrathin-film optoelectronics such as photovoltaics and photodetectors. Based on plasmonic graphene electric double-layer (EDL) transistor, a novel scheme of photodetection has been demonstrated using plasmonic enhanced local field gating. The resulting tuning of interfacial capacitance as well as the quantum capacitance of graphene manifested as extraordinary photoconductivity and hence photoresponse.

Interface science of virtual GaN substrates on Si(111) via Sc2O3/Y2O3 buffers: Experiment and theory

NASA Astrophysics Data System (ADS)

Tarnawska, L.; Dabrowski, J.; Grzela, T.; Lehmann, M.; Niermann, T.; Paszkiewicz, R.; Storck, P.; Schroeder, T.

2013-06-01

The final film quality of GaN on foreign substrates is known to crucially depend on the initial GaN interface and nucleation characteristics. To shed light on these characteristics of recently pioneered virtual, hexagonal GaN(0001) substrates on Si(111) via step graded Sc2O3(111)/Y2O3(111) buffers, a complex GaN(0001)/Sc2O3(111) interface structure model and the initial nucleation scenario is derived from a combined experimental (reflection high energy electron diffraction and X-ray photoelectron spectroscopy) and theoretical ab initio study. It is shown that the GaN/Sc2O3 interface chemistry is determined by a N-Ga-O-Sc atomic arrangement leading to N-polar GaN films. However, the atomic GaN(0001)/Sc2O3(111) interface configuration is complex and local perturbations might be at the origin of Ga-polar inversion domains in the mainly N-polar GaN films. The initial growth of GaN on Sc2O3 is characterized by an ultrathin N-Ga-O-Sc wetting layer which carries tensile strain and relaxes with increasing thickness. Further GaN deposition results in the formation of 3D islands which fully relax before island coalescence occurs. The implications of the GaN/Sc2O3 interface configuration, the 3D nucleation growth mode, and the coalescence process of misaligned islands are discussed with respect to the defect characteristics (inversion domains, cubic inclusions, threading dislocations) of the final GaN layer.

The Spallation Neutron Source accelerator system design

NASA Astrophysics Data System (ADS)

Henderson, S.; Abraham, W.; Aleksandrov, A.; Allen, C.; Alonso, J.; Anderson, D.; Arenius, D.; Arthur, T.; Assadi, S.; Ayers, J.; Bach, P.; Badea, V.; Battle, R.; Beebe-Wang, J.; Bergmann, B.; Bernardin, J.; Bhatia, T.; Billen, J.; Birke, T.; Bjorklund, E.; Blaskiewicz, M.; Blind, B.; Blokland, W.; Bookwalter, V.; Borovina, D.; Bowling, S.; Bradley, J.; Brantley, C.; Brennan, J.; Brodowski, J.; Brown, S.; Brown, R.; Bruce, D.; Bultman, N.; Cameron, P.; Campisi, I.; Casagrande, F.; Catalan-Lasheras, N.; Champion, M.; Champion, M.; Chen, Z.; Cheng, D.; Cho, Y.; Christensen, K.; Chu, C.; Cleaves, J.; Connolly, R.; Cote, T.; Cousineau, S.; Crandall, K.; Creel, J.; Crofford, M.; Cull, P.; Cutler, R.; Dabney, R.; Dalesio, L.; Daly, E.; Damm, R.; Danilov, V.; Davino, D.; Davis, K.; Dawson, C.; Day, L.; Deibele, C.; Delayen, J.; DeLong, J.; Demello, A.; DeVan, W.; Digennaro, R.; Dixon, K.; Dodson, G.; Doleans, M.; Doolittle, L.; Doss, J.; Drury, M.; Elliot, T.; Ellis, S.; Error, J.; Fazekas, J.; Fedotov, A.; Feng, P.; Fischer, J.; Fox, W.; Fuja, R.; Funk, W.; Galambos, J.; Ganni, V.; Garnett, R.; Geng, X.; Gentzlinger, R.; Giannella, M.; Gibson, P.; Gillis, R.; Gioia, J.; Gordon, J.; Gough, R.; Greer, J.; Gregory, W.; Gribble, R.; Grice, W.; Gurd, D.; Gurd, P.; Guthrie, A.; Hahn, H.; Hardek, T.; Hardekopf, R.; Harrison, J.; Hatfield, D.; He, P.; Hechler, M.; Heistermann, F.; Helus, S.; Hiatt, T.; Hicks, S.; Hill, J.; Hill, J.; Hoff, L.; Hoff, M.; Hogan, J.; Holding, M.; Holik, P.; Holmes, J.; Holtkamp, N.; Hovater, C.; Howell, M.; Hseuh, H.; Huhn, A.; Hunter, T.; Ilg, T.; Jackson, J.; Jain, A.; Jason, A.; Jeon, D.; Johnson, G.; Jones, A.; Joseph, S.; Justice, A.; Kang, Y.; Kasemir, K.; Keller, R.; Kersevan, R.; Kerstiens, D.; Kesselman, M.; Kim, S.; Kneisel, P.; Kravchuk, L.; Kuneli, T.; Kurennoy, S.; Kustom, R.; Kwon, S.; Ladd, P.; Lambiase, R.; Lee, Y. Y.; Leitner, M.; Leung, K.-N.; Lewis, S.; Liaw, C.; Lionberger, C.; Lo, C. C.; Long, C.; Ludewig, H.; Ludvig, J.; Luft, P.; Lynch, M.; Ma, H.; MacGill, R.; Macha, K.; Madre, B.; Mahler, G.; Mahoney, K.; Maines, J.; Mammosser, J.; Mann, T.; Marneris, I.; Marroquin, P.; Martineau, R.; Matsumoto, K.; McCarthy, M.; McChesney, C.; McGahern, W.; McGehee, P.; Meng, W.; Merz, B.; Meyer, R.; Meyer, R.; Miller, B.; Mitchell, R.; Mize, J.; Monroy, M.; Munro, J.; Murdoch, G.; Musson, J.; Nath, S.; Nelson, R.; Nelson, R.; O`Hara, J.; Olsen, D.; Oren, W.; Oshatz, D.; Owens, T.; Pai, C.; Papaphilippou, I.; Patterson, N.; Patterson, J.; Pearson, C.; Pelaia, T.; Pieck, M.; Piller, C.; Plawski, T.; Plum, M.; Pogge, J.; Power, J.; Powers, T.; Preble, J.; Prokop, M.; Pruyn, J.; Purcell, D.; Rank, J.; Raparia, D.; Ratti, A.; Reass, W.; Reece, K.; Rees, D.; Regan, A.; Regis, M.; Reijonen, J.; Rej, D.; Richards, D.; Richied, D.; Rode, C.; Rodriguez, W.; Rodriguez, M.; Rohlev, A.; Rose, C.; Roseberry, T.; Rowton, L.; Roybal, W.; Rust, K.; Salazer, G.; Sandberg, J.; Saunders, J.; Schenkel, T.; Schneider, W.; Schrage, D.; Schubert, J.; Severino, F.; Shafer, R.; Shea, T.; Shishlo, A.; Shoaee, H.; Sibley, C.; Sims, J.; Smee, S.; Smith, J.; Smith, K.; Spitz, R.; Staples, J.; Stein, P.; Stettler, M.; Stirbet, M.; Stockli, M.; Stone, W.; Stout, D.; Stovall, J.; Strelo, W.; Strong, H.; Sundelin, R.; Syversrud, D.; Szajbler, M.; Takeda, H.; Tallerico, P.; Tang, J.; Tanke, E.; Tepikian, S.; Thomae, R.; Thompson, D.; Thomson, D.; Thuot, M.; Treml, C.; Tsoupas, N.; Tuozzolo, J.; Tuzel, W.; Vassioutchenko, A.; Virostek, S.; Wallig, J.; Wanderer, P.; Wang, Y.; Wang, J. G.; Wangler, T.; Warren, D.; Wei, J.; Weiss, D.; Welton, R.; Weng, J.; Weng, W.-T.; Wezensky, M.; White, M.; Whitlatch, T.; Williams, D.; Williams, E.; Wilson, K.; Wiseman, M.; Wood, R.; Wright, P.; Wu, A.; Ybarrolaza, N.; Young, K.; Young, L.; Yourd, R.; Zachoszcz, A.; Zaltsman, A.; Zhang, S.; Zhang, W.; Zhang, Y.; Zhukov, A.

2014-11-01

The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.

"Transformation Tuesday": Temporal context and post valence influence the provision of social support on social media.

PubMed

Vogel, Erin A; Rose, Jason P; Crane, Chantal

2018-01-01

Social network sites (SNSs) such as Facebook have become integral in the development and maintenance of interpersonal relationships. Users of SNSs seek social support and validation, often using posts that illustrate how they have changed over time. The purpose of the present research is to examine how the valence and temporal context of an SNS post affect the likelihood of other users providing social support. Participants viewed hypothetical SNS posts and reported their intentions to provide social support to the users. Results revealed that participants were more likely to provide social support for posts that were positive and included temporal context (i.e., depicted improvement over time; Study 1). Furthermore, this research suggests that visual representations of change over time are needed to elicit social support (Study 2). Results are discussed in terms of their practical implications for SNS users and theoretical implications for the literature on social support and social media.

Remote N2 plasma treatment to deposit ultrathin high-k dielectric as tunneling contact layer for single-layer MoS2 MOSFET

NASA Astrophysics Data System (ADS)

Qian, Qingkai; Zhang, Zhaofu; Hua, Mengyuan; Wei, Jin; Lei, Jiacheng; Chen, Kevin J.

2017-12-01

Remote N2 plasma treatment is explored as a surface functionalization technique to deposit ultrathin high-k dielectric on single-layer MoS2. The ultrathin dielectric is used as a tunneling contact layer, which also serves as an interfacial layer below the gate region for fabricating top-gate MoS2 metal-oxide-semiconductor field-effect transistors (MOSFETs). The fabricated devices exhibited small hysteresis and mobility as high as 14 cm2·V-1·s-1. The contact resistance was significantly reduced, which resulted in the increase of drain current from 20 to 56 µA/µm. The contact resistance reduction can be attributed to the alleviated metal-MoS2 interface reaction and the preserved conductivity of MoS2 below the source/drain metal contact.

Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells.

PubMed

Pathi, Prathap; Peer, Akshit; Biswas, Rana

2017-01-13

Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm) and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm) and is slightly lower (by ~5%) at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm) silicon and just 1%-2% for thicker (>100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm² photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

Screening for Muir-Torre syndrome using mismatch repair protein immunohistochemistry of sebaceous neoplasms.

PubMed

Roberts, Maegan E; Riegert-Johnson, Douglas L; Thomas, Brittany C; Thomas, Colleen S; Heckman, Michael G; Krishna, Murli; DiCaudo, David J; Bridges, Alina G; Hunt, Katherine S; Rumilla, Kandelaria M; Cappel, Mark A

2013-06-01

Screening for the Muir-Torre variant of Lynch Syndrome (LS) using Mismatch Repair (MMR) gene immunohistochemistry (IHC) on sebaceous neoplasms (SNs) is technically feasible. To date, research into the clinical utility of MMR IHC for this indication is limited. We conducted a retrospective chart review of 90 patients with MMR IHC completed on at least one SN from January 2005 to May 2010. SNs included were adenomas, epitheliomas, carcinomas and basal and squamous cell carcinomas with sebaceous differentiation. Of the 90 patients, 13 (14 %) had genetically confirmed or fulfilled clinical criteria for a diagnosis of MTS and 51 patients (57 %) presented with an abnormal MMR IHC result (loss of one or more MMR proteins) on at least one SN. Abnormal IHC had a sensitivity of 85 %, specificity of 48 %, positive predictive value (PPV) of 22 % and negative predictive value (NPV) of 95 % when evaluating for MTS. When personal or family history of colorectal cancer (≥2 family members with a history of colorectal cancer) was taken into consideration, ignoring IHC results, sensitivity was 92 %, specificity was 99 %, PPV was 92 % and NPV was 99 %. MMR IHC on SNs when used to screen for MTS has poor diagnostic utility. We recommend that MMR IHC not be performed routinely on SNs when the patient does not have either personal or family history of colorectal cancer.

Solar Absorber Cu 2 ZnSnS 4 and its Parent Multilayers ZnS/SnS 2 /Cu 2 S Synthesized by Atomic Layer Deposition and Analyzed by X-ray Photoelectron Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baryshev, Sergey V.; Riha, Shannon C.; Zinovev, Alexander V.

2015-06-01

Presented here are results of x-ray photoelectron spectroscopy (XPS) on multilayers of metal-sulfide binaries ZnS, SnS2, and Cu2S grown by atomic layer deposition (ALD) on Si substrates, and of Cu2ZnSnS4 (CZTS) formed upon 450 °C annealing of the parent multilayer ZnS/SnS2/Cu2S. Survey and detailed spectral analysis of the multilayer ZnS/SnS2/Cu2S are presented step-wise, as each layer was sequentially added by ALD. The set of data is finalized with spectra of the resulting alloy CZTS. XPS analyses indicate significant mixing between SnS2 and Cu2S, which favors CZTS formation within the ALD approach.

Development of SNS Stream Analysis Based on Forest Disaster Warning Information Service System

NASA Astrophysics Data System (ADS)

Oh, J.; KIM, D.; Kang, M.; Woo, C.; Kim, D.; Seo, J.; Lee, C.; Yoon, H.; Heon, S.

2017-12-01

Forest disasters, such as landslides and wildfires, cause huge economic losses and casualties, and the cost of recovery is increasing every year. While forest disaster mitigation technologies have been focused on the development of prevention and response technologies, they are now required to evolve into evacuation and border evacuation, and to develop technologies fused with ICT. In this study, we analyze the SNS (Social Network Service) stream and implement a system to detect the message that the forest disaster occurred or the forest disaster, and search the keyword related to the forest disaster in advance in real time. It is possible to detect more accurate forest disaster messages by repeatedly learning the retrieved results using machine learning techniques. To do this, we designed and implemented a system based on Hadoop and Spark, a distributed parallel processing platform, to handle Twitter stream messages that open SNS. In order to develop the technology to notify the information of forest disaster risk, a linkage of technology such as CBS (Cell Broadcasting System) based on mobile communication, internet-based civil defense siren, SNS and the legal and institutional issues for applying these technologies are examined. And the protocol of the forest disaster warning information service system that can deliver the SNS analysis result was developed. As a result, it was possible to grasp real-time forest disaster situation by real-time big data analysis of SNS that occurred during forest disasters. In addition, we confirmed that it is possible to rapidly propagate alarm or warning according to the disaster situation by using the function of the forest disaster warning information notification service. However, the limitation of system application due to the restriction of opening and sharing of SNS data currently in service and the disclosure of personal information remains a problem to be solved in the future. Keyword : SNS stream, Big data, Machine learning techniques, CBS, Forest disaster warning information service system Acknowledgement : This research was supported by the Forestry Technology 2015 Forestry Technology Research and Development Project (Planning project).

High-speed growth of TiO2 nanotube arrays with gradient pore diameter and ultrathin tube wall under high-field anodization

NASA Astrophysics Data System (ADS)

Yuan, Xiaoliang; Zheng, Maojun; Ma, Li; Shen, Wenzhong

2010-10-01

Highly ordered TiO2 nanotubular arrays have been prepared by two-step anodization under high field. The high anodizing current densities lead to a high-speed film growth (0.40-1.00 µm min - 1), which is nearly 16 times faster than traditional fabrication of TiO2 at low field. It was found that an annealing process of Ti foil is an effective approach to get a monodisperse and double-pass TiO2 nanotubular layer with a gradient pore diameter and ultrathin tube wall (nearly 10 nm). A higher anodic voltage and longer anodization time are beneficial to the formation of ultrathin tube walls. This approach is simple and cost-effective in fabricating high-quality ordered TiO2 nanotubular arrays for practical applications.

High-speed growth of TiO2 nanotube arrays with gradient pore diameter and ultrathin tube wall under high-field anodization.

PubMed

Yuan, Xiaoliang; Zheng, Maojun; Ma, Li; Shen, Wenzhong

2010-10-08

Highly ordered TiO(2) nanotubular arrays have been prepared by two-step anodization under high field. The high anodizing current densities lead to a high-speed film growth (0.40-1.00 microm min(-1)), which is nearly 16 times faster than traditional fabrication of TiO(2) at low field. It was found that an annealing process of Ti foil is an effective approach to get a monodisperse and double-pass TiO(2) nanotubular layer with a gradient pore diameter and ultrathin tube wall (nearly 10 nm). A higher anodic voltage and longer anodization time are beneficial to the formation of ultrathin tube walls. This approach is simple and cost-effective in fabricating high-quality ordered TiO(2) nanotubular arrays for practical applications.

Three-dimensional TiO2 nanowire@NiMoO4 ultrathin nanosheet core-shell arrays for lithium ion batteries

NASA Astrophysics Data System (ADS)

Cao, Minglei; Bu, Yi; Lv, Xiaowei; Jiang, Xingxing; Wang, Lichuan; Dai, Sirui; Wang, Mingkui; Shen, Yan

2018-03-01

This study reports a general and rational two-step hydrothermal strategy to fabricate three-dimensional (3D) TiO2 nanowire@NiMoO4 ultrathin nanosheet core-shell arrays (TNAs-NMO) as additives-free anodes for lithium-ion batteries (LIBs). The TNAs-NMO electrode delivers a reversible capacity of up to 446.6 mA h g-1 over 120 cycles at the current density of 0.2 A g-1 and a high rate capacity of 234.2 mA h g-1 at 2.0 A g-1. Impressively, the capacity retention efficiency is 74.7% after 2500 cycles at the high rate of 2.0 A g-1. In addition, the full cell consisting of TNAs-NMO anode and LCO cathode can afford a specific energy of up to 220.3 W h kg-1 (based on the entire mass of both electrodes). The high electrochemical performance of the TNAs-NMO electrode is ascribed to its 3D core-shell nanowire array architecture, in which the TiO2 nanowire arrays (TNAs) and the ultrathin NiMoO4 nanosheets exhibit strong synergistic effects. The TNAs maintain mechanical integrity of the electrode and the ultrathin NiMoO4 nanosheets contribute to high capacity and favorable electronic conductivity.

Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes.

PubMed

Gu, Yu; Wang, Wei-Wei; Li, Yi-Juan; Wu, Qi-Hui; Tang, Shuai; Yan, Jia-Wei; Zheng, Ming-Sen; Wu, De-Yin; Fan, Chun-Hai; Hu, Wei-Qiang; Chen, Zhao-Bin; Fang, Yuan; Zhang, Qing-Hong; Dong, Quan-Feng; Mao, Bing-Wei

2018-04-09

Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity. The polished metal anodes exhibit significantly enhanced cycling stability, specifically the lithium anodes can cycle for over 200 times at a real current density of 2 mA cm -2 with 100% depth of discharge. Our work illustrates that an ultra-smooth ultra-thin solid-electrolyte interphase may be robust enough to suppress dendrite growth and thus serve as an initial layer for further improved protection of alkali metal anodes.

Coexistence of colossal stress and texture gradients in sputter deposited nanocrystalline ultra-thin metal films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuru, Yener; Welzel, Udo; Mittemeijer, Eric J.

2014-12-01

This paper demonstrates experimentally that ultra-thin, nanocrystalline films can exhibit coexisting colossal stress and texture depth gradients. Their quantitative determination is possible by X-ray diffraction experiments. Whereas a uniform texture by itself is known to generally cause curvature in so-called sin{sup 2}ψ plots, it is shown that the combined action of texture and stress gradients provides a separate source of curvature in sin{sup 2}ψ plots (i.e., even in cases where a uniform texture does not induce such curvature). On this basis, the texture and stress depth profiles of a nanocrystalline, ultra-thin (50 nm) tungsten film could be determined.

Definition of Capabilities Needed for a Single Event Effects Test Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riemer, Bernie; Gallmeier, Franz X.

The Federal Aviation Administration (FAA) is contemplating new regulations mandating testing of the vulnerability of flight-critical avionics to single event effects (SEE). A limited number of high-energy neutron test facilities currently serve the SEE industrial and institutional research community. The FAA recognizes that existing facilities have insufficient test capacity to meet new demand from such mandates; it desires more flexible irradiation capabilities to test complete, large systems and would like capabilities to address greater concerns for thermal neutrons. For this reason, the FAA funded this study by Spallation Neutron Source (SNS) staff with the ultimate aim of developing options formore » SEE test facilities using high-energy neutrons at the SNS complex. After an investigation of current SEE test practices and assessment of future testing requirements, three concepts were identified covering a range of test functionality, neutron flux levels, and fidelity to the atmospheric neutron spectrum. The costs and times required to complete each facility were also estimated. SEE testing is generally performed by accelerating the event rate to a point where the effects are still dominated by single events and double event causes of failures are negligible. In practice, acceleration factors of as high as 10 6 are applicable for component testing, whereas for systems testing acceleration factors of 10 4 seem to be the upper limit. It is strongly desirable that the irradiation facility be tunable over a large range of high-energy neutron fluxes of 10 2 - 10 4 n/cm²/s for systems testing and from 10 4 - 10 7 n/cm²/s for components testing. The most capable, most flexible, and highest-test-capacity option is a new stand-alone target station named the High-Energy neutron Test Station (HETS). It is also the most expensive option, with a cost to complete of approximately $100 million. Dual test enclosures would allow for simultaneous testing activity effectively doubling overall test capacity per HETS operating hour. Using about 1 kilowatt (kW) of proton power extracted from the accelerator before injection in the accumulator ring, its operation would be unnoticeable by neutron scattering users at the SNS target station. The H beam laser stripping technique would allow for control of beam power on the HETS target independent from power delivered to the SNS. Large systems with frontal areas of up to 1 x 2 m² could be accommodated with integral high-energy flux values (above 10 megaelectron-volt, or MeV) to at most 10 4 n/cm²/s; components could also be tested with flux levels to at most 10 7 n/cm²/s on beam sizes of up to 0.2 x 0.2 m². Selectable moderating material and neutron filters would allow tailoring of the neutron spectrum to user demands; charged particle deflectors could be switched to allow or deflect protons, pions, and muons. It is estimated that HETS would take 5 years to complete after award of contract, including engineering design and construction. Commissioning would take at least another 6 months. Interference with SNS principal operations was not considered in the construction time estimate; connection of the proton transport line and tunnel from the accelerator high energy beam transport (HEBT) and construction around existing site utilities would require careful planning and coordination with beam operations at the SNS. A high-energy (HE) neutron test facility using an available beam line on the SNS target station is a technically and financially attractive option. Inspired by the new ChipIR instrument on the ISIS TS 2 spallation source in the UK, a similar facility could be placed on an unused beam line in the SNS instrument hall [e.g., on beam line 8 (both A and B channels would be needed) or on beam line 10]. The performance would approach that of an HETS (~80%), but it would be operationally more limited, with only a single user at a time. Space is more limited, so the maximum system size would be about half of that in an HETS. Flexibility to tailor the spectrum would be somewhat more limited. While this concept was not as fully developed and characterized, preliminary work indicates very high HE flux levels should be possible, with ample thermal neutrons as well. Flux control would be more difficult than at HETS because proton power on target be whatever the SNS was operating at for neutron scattering. Neutron attenuation devices would have to be employed with as-yet undetermined control resolution. However, no new buildings would be needed, and the necessary utilities are already present in the SNS Experiment Hall. The estimated cost for a beam line option is around $15 million; the time to complete would be 3 years after award of contract, plus at least 6 months for commissioning. Interference of construction activities with SNS operations should be negligible. This option would require negotiation with the Department of Energy Basic Energy Sciences (BES) office -- the primary stakeholder of SNS -- for an application outside the usual scope of neutron scattering sciences. Furthermore, these presently open beam lines are highly desirable locations for proposed neutron scattering instruments and obtaining one of them for an SEE test facility will come only with persuasive and timely arguments to SNS leadership and the DOE BES. The third option is a tunnel extension/target cave facility providing the most basic system-level irradiation capability with minimal flexibility. Again not as well developed a concept as HETS, it would use a laser-stripping technique like an HETS, redirecting protons to a tunnel similar to the initial HETS proton transport tunnel. Indeed, this concept is intended to be upgradable to a full HETS facility. Only a small fraction of a watt of proton power would be used in this basic configuration, though. An uncooled target and primitive shielding arrangement would provide beam on modestly sized systems that must be placed in close proximity to the target. The neutron fluence would be less uniform over the system than with the HETS or the beam line option. A data acquisition room and support area would be located on the ground level; access to the target cave would be via elevator and/or stairway. As a result of the required excavation, new tunnel construction, shielding, data acquisition building, utilities, and other items, the estimated cost is $30 million. The time to complete is expected be more than 3 years; here again construction interference with SNS operations has not been accounted for, but it could have a significant impact.« less

The independent relationship between trouble controlling Facebook use, time spent on the site and distress

PubMed Central

Muench, Fredrick; Hayes, Marie; Kuerbis, Alexis; Shao, Sijing

2015-01-01

Background and Aims There is an emerging literature base on the relationship between maladaptive traits and “addiction” to social networking sites. These studies have operationalized addiction as either spending excessive amounts of time on social networking sites (SNS) or trouble controlling SNS use, but have not assessed the unique contribution of each of these constructs on outcomes in the same models. Moreover, these studies have exclusively been conducted with younger people rather than a heterogeneous sample. This study examined the independent relationship of a brief Facebook addiction scale, time spent on Facebook, and Facebook checking on positive and negative social domains, while controlling for self-esteem and social desirability. Methods Participants were recruited using e-mail, SNS posts and through Amazon’s MTurk system. The sample included 489 respondents ages from 18 to approximately 70, who completed a 10–15 minute survey. Results Results indicate that neither time spent on Facebook nor Facebook checking was significantly associated with either self-esteem, fear of negative social evaluation or social comparison, while SNS addiction symptoms were each independently associated with Facebook usage. Neither time spent on Facebook nor SNS addiction symptoms were associated with positive social relationships. Discussion Overall results suggest that time on SNS and trouble controlling use should be considered independent constructs and that interventions should target underlying loss of control as the primary intervention target above ego syntonic time spent on the site. PMID:26551906

Comparing farmers' market revenue trends before and after the implementation of a monetary incentive for recipients of food assistance.

PubMed

Freedman, Darcy A; Mattison-Faye, Amy; Alia, Kassandra; Guest, M Aaron; Hébert, James R

2014-05-22

We examined the influence of an intervention to increase fruit and vegetable purchases at farmers' markets for recipients of food assistance, Shop N Save (SNS), on revenue trends at a farmers' market located at a federally qualified health center (FQHC) in rural South Carolina. We compared revenue trends for 20 weeks before the intervention (2011) and 20 weeks after (2012). SNS provided one $5 monetary incentive per week to customers spending $5 or more in food assistance at the farmers' market. SNS was available to any farmers' market customer using Supplemental Nutrition Assistance Program (SNAP), Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), and/or Senior or WIC Farmers' Market Nutrition Program (FMNP) vouchers. Sales receipts were recorded for each transaction at the farmers' market to document payment type and the cost of the purchase. All SNS participants completed a one-time enrollment survey. A total of 336 customers self-enrolled in SNS from June through October 2012. Most SNS participants were female, African American, and patients at the FQHC. In total, the use of all forms of food assistance (SNAP, WIC, and FMNP) at the farmers' market increased significantly after the intervention (from 10% before, to 25% after, P = .003). Senior FMNP vouchers and SNAP usage increased the most. Interventions that provide incentives to recipients of food assistance programs at farmers' markets are a viable strategy for increasing food assistance usage and revenue.

Comparing Farmers’ Market Revenue Trends Before and After the Implementation of a Monetary Incentive for Recipients of Food Assistance

PubMed Central

Mattison-Faye, Amy; Alia, Kassandra; Guest, M. Aaron; Hébert, James R.

2014-01-01

Introduction We examined the influence of an intervention to increase fruit and vegetable purchases at farmers’ markets for recipients of food assistance, Shop N Save (SNS), on revenue trends at a farmers’ market located at a federally qualified health center (FQHC) in rural South Carolina. We compared revenue trends for 20 weeks before the intervention (2011) and 20 weeks after (2012). Methods SNS provided one $5 monetary incentive per week to customers spending $5 or more in food assistance at the farmers’ market. SNS was available to any farmers’ market customer using Supplemental Nutrition Assistance Program (SNAP), Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), and/or Senior or WIC Farmers’ Market Nutrition Program (FMNP) vouchers. Sales receipts were recorded for each transaction at the farmers’ market to document payment type and the cost of the purchase. All SNS participants completed a one-time enrollment survey. Results A total of 336 customers self-enrolled in SNS from June through October 2012. Most SNS participants were female, African American, and patients at the FQHC. In total, the use of all forms of food assistance (SNAP, WIC, and FMNP) at the farmers’ market increased significantly after the intervention (from 10% before, to 25% after, P = .003). Senior FMNP vouchers and SNAP usage increased the most. Conclusion Interventions that provide incentives to recipients of food assistance programs at farmers’ markets are a viable strategy for increasing food assistance usage and revenue. PMID:24854238

Problematic use of social network sites: the interactive relationship between gratifications sought and privacy concerns.

PubMed

Chen, Hsuan-Ting; Kim, Yonghwan

2013-11-01

Problematic Internet use has long been a matter of concern; however, few studies extend this line of research from general Internet use to the use of social network sites (SNSs), or explicate the problematic use of SNSs by understanding what factors may enhance or reduce users' compulsive behaviors and excessive form of use on SNSs. Building on literature that found a positive relationship between gratifications sought from the Internet and problematic Internet use, this study first explores the types of gratifications sought from SNSs and examines their relationship with problematic SNS use. It found that three types of gratifications-diversion, self-presentation, and relationship building-were positively related to problematic SNS use. In addition, with a growing body of research on SNS privacy, a moderating role of privacy concerns on SNSs has been proposed to understand how it can influence the relationship between gratifications sought from SNSs and problematic SNS use. The findings suggest that different subdimensions of privacy concerns interact with gratifications sought in different manners. In other words, privacy concerns, including unauthorized secondary use and improper access, play a more influential role in constraining the positive relationship between gratifications sought and problematic SNS use when individuals seek to build relationships on SNSs. However, if individuals seek to have diversion on SNSs, their privacy concerns will be overridden by their gratifications sought, which in turn leads to problematic SNS use. Implications of these findings for future research are discussed.

Empirical analysis of online social networks in the age of Web 2.0

NASA Astrophysics Data System (ADS)

Fu, Feng; Liu, Lianghuan; Wang, Long

2008-01-01

Today the World Wide Web is undergoing a subtle but profound shift to Web 2.0, to become more of a social web. The use of collaborative technologies such as blogs and social networking site (SNS) leads to instant online community in which people communicate rapidly and conveniently with each other. Moreover, there are growing interest and concern regarding the topological structure of these new online social networks. In this paper, we present empirical analysis of statistical properties of two important Chinese online social networks-a blogging network and an SNS open to college students. They are both emerging in the age of Web 2.0. We demonstrate that both networks possess small-world and scale-free features already observed in real-world and artificial networks. In addition, we investigate the distribution of topological distance. Furthermore, we study the correlations between degree (in/out) and degree (in/out), clustering coefficient and degree, popularity (in terms of number of page views) and in-degree (for the blogging network), respectively. We find that the blogging network shows disassortative mixing pattern, whereas the SNS network is an assortative one. Our research may help us to elucidate the self-organizing structural characteristics of these online social networks embedded in technical forms.

Skin dose for head and neck cancer patients treated with intensity-modulated radiation therapy(IMRT)

NASA Astrophysics Data System (ADS)

Fu, Hsiao-Ju; Li, Chi-Wei; Tsai, Wei-Ta; Chang, Chih-Chia; Tsang, Yuk-Wah

2017-11-01

The reliability of thermoluminescent dosimeters (ultrathin TLD) and ISP Gafchromic EBT2 film to measure the surface dose in phantom and the skin dose in head-and-neck patients treated with intensity-modulated radiation therapy technique(IMRT) is the research focus. Seven-field treatment plans with prescribed dose of 180 cGy were performed on Eclipse treatment planning system which utilized pencil beam calculation algorithm(PBC). In calibration tests, the variance coefficient of the ultrathin TLDs were within 3%. The points on the calibration curve of the Gafchromic film was within 1% variation. Five measurements were taken on phantom using ultrathin TLD and EBT2 film respectively. The measured mean surface doses between ultrathin TLD or EBT2 film were within 5% deviation. Skin doses of 6 patients were measured for initial 5 fractions and the mean dose per-fraction was calculated. If the extrapolated doses for 30 fractions were below 4000 cGy, the skin reaction grading observed according to Radiation Therapy Oncology Group (RTOG) was either grade 1 or grade 2. If surface dose exceeded 5000 cGy in 32 fractions, then grade 3 skin reactions were observed.

Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, Andrew J.; Temperton, Robert H.; Handrup, Karsten

2014-06-21

The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4′-dicarbo-xylato) -ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO,more » therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombination effects and improved efficiencies of future devices.« less

Ultrathin TiO2 layer coated-CdS spheres core-shell nanocomposite with enhanced visible-light photoactivity.

PubMed

Chen, Zhang; Xu, Yi-Jun

2013-12-26

Development of various strategies for controllable fabrication of core-shell nanocomposites (CSNs) with highly active photocatalytic performance has been attracting ever-increasing research attention. In particular, control of the ultrathin layer TiO2 shell in constructing CSNs in an aqueous phase is a significant but technologically challenging issue. Here, this paper demonstrates the interface assembly synthesis of CdS nanospheres@TiO2 core-shell photocatalyst via the electrostatic interaction of negatively charged water-stable titania precursor with positively charged CdS nanospheres (CdS NSPs), followed by the formation of the ultrathin-layer TiO2 shell through a facile refluxing process in aqueous phase. The as-formed CdS NSPs@TiO2 core-shell nanohybrid exhibits a high visible-light-driven photoactivity for selective transformation and reduction of heavy metal ions. The ultrathin TiO2 layer coated on CdS NSPs results in excellent light transmission property, enhanced adsorption capacity, and improved transfer of charge carriers and lifespan of photoinduced electron-hole pairs, which would prominently contribute to the significant photoactivity enhancement. It is anticipated that this facile aqueous-phase synthesis strategy could be extended to design a variety of more efficient CSN photocatalysts with controllable morphology toward target applications in diverse photoredox processes.

Social Networking Sites and Addiction: Ten Lessons Learned

PubMed Central

Kuss, Daria J.; Griffiths, Mark D.

2017-01-01

Online social networking sites (SNSs) have gained increasing popularity in the last decade, with individuals engaging in SNSs to connect with others who share similar interests. The perceived need to be online may result in compulsive use of SNSs, which in extreme cases may result in symptoms and consequences traditionally associated with substance-related addictions. In order to present new insights into online social networking and addiction, in this paper, 10 lessons learned concerning online social networking sites and addiction based on the insights derived from recent empirical research will be presented. These are: (i) social networking and social media use are not the same; (ii) social networking is eclectic; (iii) social networking is a way of being; (iv) individuals can become addicted to using social networking sites; (v) Facebook addiction is only one example of SNS addiction; (vi) fear of missing out (FOMO) may be part of SNS addiction; (vii) smartphone addiction may be part of SNS addiction; (viii) nomophobia may be part of SNS addiction; (ix) there are sociodemographic differences in SNS addiction; and (x) there are methodological problems with research to date. These are discussed in turn. Recommendations for research and clinical applications are provided. PMID:28304359

Social Networking Sites and Addiction: Ten Lessons Learned.

PubMed

Kuss, Daria J; Griffiths, Mark D

2017-03-17

Online social networking sites (SNSs) have gained increasing popularity in the last decade, with individuals engaging in SNSs to connect with others who share similar interests. The perceived need to be online may result in compulsive use of SNSs, which in extreme cases may result in symptoms and consequences traditionally associated with substance-related addictions. In order to present new insights into online social networking and addiction, in this paper, 10 lessons learned concerning online social networking sites and addiction based on the insights derived from recent empirical research will be presented. These are: (i) social networking and social media use are not the same; (ii) social networking is eclectic; (iii) social networking is a way of being; (iv) individuals can become addicted to using social networking sites; (v) Facebook addiction is only one example of SNS addiction; (vi) fear of missing out (FOMO) may be part of SNS addiction; (vii) smartphone addiction may be part of SNS addiction; (viii) nomophobia may be part of SNS addiction; (ix) there are sociodemographic differences in SNS addiction; and (x) there are methodological problems with research to date. These are discussed in turn. Recommendations for research and clinical applications are provided.

Sympathetic overactivity in hypertension and cardiovascular disease.

PubMed

Manolis, A J; Poulimenos, L E; Kallistratos, M S; Gavras, I; Gavras, H

2014-01-01

From the first description of its anatomy by T. Willis to the novel therapeutic manipulations, it is unanimously recognized that the sympathetic nervous system (SNS) holds a crucial role in cardiovascular homeostasis. The introduction of sophisticated techniques, as microneurography and regional norepinephrine spillover provided the evidence for the role of sympathetic overactivity in various cardiovascular disease entities. Sympathetic activation is common in patients with essential hypertension and contributes to initiation, maintenance and progression of the disease and it contributes to the manifestation of its major complications. A considerable body of evidence relates SNS overactivity with high sodium intake in experimental animals and humans and the underlying mechanisms have nowadays been elucidated. SNS activity is more pronounced in patients with resistant hypertension and there are several conditions that lead to this phenomenon, as older age, kidney disease, obesity and metabolic syndrome, mental stress and sleep apnea. SNS overactivity holds also a key physiopathological role in heart failure, acute coronary syndromes and arrhythmias. Moreover, inhibition of sympathetic overactivity by various means, including central SNS suppressing drugs, peripheral alpha- and beta- adrenergic receptor blockers, or novel approaches as renal sympathetic denervation have been used successfully in the treatment of all these disorders.

Calculations vs. Measurements for Remnant Dose Rates from SNS Spent Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popova, Irina I.; Gallmeier, Franz X.; Trotter, Steven M.

The Spallation Neutron Source (SNS) in Oak Ridge, Tennessee, is an accelerator driven neutron scattering facility for materials research. Presently SNS is capable to operate at 1.4 MW proton beam power incident on a mercury target with a proton beam energy of 1 GeV and 60 Hz repetition rate. SNS target system components are periodically replaced because they reach their end-of-life due to radiation induced material damage. Target vessel, which houses mercury target, is exchanged about two-three times per year and the proton beam window (PBW) is exchanged every two – three years.Each spent structure that leaves the SNS sitemore » requires supporting documentation with radionuclide inventory and dose rate prediction for the time of the transportation. Neutronics analyses are performed, assuming realistic irradiation history and decay case to ensure that the container/package, housing the structure, is compliant with the waste management regulations. Analyses are complex due to geometry, multi-code usage and following data treatment.To validate analyses, measurements of dose rates from the spent target vessel # 13 and PBW module #5 were performed. Neutronics analyses were performed to calculate residual dose rates from both structures for the time of measurements.« less

Exploring the predicted effect of social networking site use on perceived social capital and psychological well-being of Chinese international students in Japan.

PubMed

Guo, Yu; Li, Yiwei; Ito, Naoya

2014-01-01

This study investigated how social networking sites (SNSs) use by Chinese international students in Japan influenced their perceived social capital and psychological well-being. In addition, it examined how, as sojourners, Chinese international students' perceived acculturative stress varied. Data were collected from 142 Chinese international students. The results indicated that the intensity of SNS use was unable to predict individuals' perceived social capital and psychological well-being. The effect of SNS use varied according to the functions it serves. Specifically, SNS use for social and informational functions (SIF) increased individuals' levels of perceived bridging social capital and perceived life satisfaction, while SNS use for entertaining recreational functions (ERF) was unable to predict perceived social capital but increased individuals' levels of loneliness. It was also found that, in the intercultural environment, Chinese international students' levels of perceived acculturative stress were decreased by their perceived bonding social capital and increased by their perceived loneliness but had no relationship with their SNS use. Findings of the study suggest that individuals using SNSs to stay informed and connected will benefit with regard to their social network building and psychological well-being.

Synthesis of ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper as integrated high-performance electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Deng, Fangze; Yu, Lin; Cheng, Gao; Lin, Ting; Sun, Ming; Ye, Fei; Li, Yongfeng

2014-04-01

Two-dimensional ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper (CFP) are synthesized through a facile solvothermal method combined with a post thermal treatment. The well interconnected ultrathin NiCo2O4 nanosheets directly grown on the carbon nanofibers could allow for easy diffusion of the electrolyte, shorten the transport path of ion and electron and accommodate the strain during cycling. As a result, superior pseudocapacitive performance is achieved with large specific capacitance of 999 F g-1 at a high current density of 20 A g-1. The capacitance loss is 15.6% after 3000 cycles at a current density of 10 A g-1, displaying good cycle ability and high rate capability.

Adiabatic demagnetization of the antiferromagnetic spin-1/2 Heisenberg hexagonal cluster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deb, Moumita, E-mail: moumitadeb44@gmail.com; Ghosh, Asim Kumar, E-mail: asimkumar96@yahoo.com

2016-05-23

Exact analytic expressions of eigenvalues of the antiferromagnetic spin-1/2 Heisenberg hexagon in the presence of uniform magnetic field have been obtained. Magnetization process, nature of isentrops and properties of magneto caloric effect in terms of adiabatic demagnetization have been investigated. Theoretical results have been used to study the magneto caloric effect of the spin-1/2 Heisenberg hexagonal compound Cu{sub 3}WO{sub 6}.

Confinement of holes and electrons in blue organic light-emitting diodes with additional red emissive layers

NASA Astrophysics Data System (ADS)

Kang, Jin Sung; Yoo, Seung Il; Kim, Jin Wook; Yoon, Geum Jae; Yi, Seungjun; Kim, Woo Young

2016-02-01

We used various emissive layer (EML) structures with ultrathin red EMLs to enhance the charge carrier balance and carrier recombination rate in blue PHOLED devices. These EML materials have different energy gaps between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. The ultrathin red EMLs, which were inserted in between the blue EMLs, effectively confined the charge carriers in EML, and increased the carrier recombination rate. The thickness of the individual EML was optimized, under 30 nm of the total thickness of EML. The blue PHOLEDs with ultrathin red EMLs achieved a luminous efficiency of 19.24 cd/A, which was 28.7% higher than those without ultrathin red EMLs, and the maximum external quantum efficiency was 11.81% at 500 cd/m2.

Thickness-dependence of optical constants for Ta2O5 ultrathin films

NASA Astrophysics Data System (ADS)

Zhang, Dong-Xu; Zheng, Yu-Xiang; Cai, Qing-Yuan; Lin, Wei; Wu, Kang-Ning; Mao, Peng-Hui; Zhang, Rong-Jun; Zhao, Hai-bin; Chen, Liang-Yao

2012-09-01

An effective method for determining the optical constants of Ta2O5 thin films deposited on crystal silicon (c-Si) using spectroscopic ellipsometry (SE) measurement with a two-film model (ambient-oxide-interlayer-substrate) was presented. Ta2O5 thin films with thickness range of 1-400 nm have been prepared by the electron beam evaporation (EBE) method. We find that the refractive indices of Ta2O5 ultrathin films less than 40 nm drop with the decreasing thickness, while the other ones are close to those of bulk Ta2O5. This phenomenon was due to the existence of an interfacial oxide region and the surface roughness of the film, which was confirmed by the measurement of atomic force microscopy (AFM). Optical properties of ultrathin film varying with the thickness are useful for the design and manufacture of nano-scaled thin-film devices.

Ultra-thin silicon oxide layers on crystalline silicon wafers: Comparison of advanced oxidation techniques with respect to chemically abrupt SiO2/Si interfaces with low defect densities

NASA Astrophysics Data System (ADS)

Stegemann, Bert; Gad, Karim M.; Balamou, Patrice; Sixtensson, Daniel; Vössing, Daniel; Kasemann, Martin; Angermann, Heike

2017-02-01

Six advanced oxidation techniques were analyzed, evaluated and compared with respect to the preparation of high-quality ultra-thin oxide layers on crystalline silicon. The resulting electronic and chemical SiO2/Si interface properties were determined by a combined x-ray photoemission (XPS) and surface photovoltage (SPV) investigation. Depending on the oxidation technique, chemically abrupt SiO2/Si interfaces with low densities of interface states were fabricated on c-Si either at low temperatures, at short times, or in wet-chemical environment, resulting in each case in excellent interface passivation. Moreover, the beneficial effect of a subsequent forming gas annealing (FGA) step for the passivation of the SiO2/Si interface of ultra-thin oxide layers has been proven. Chemically abrupt SiO2/Si interfaces have been shown to generate less interface defect states.

Ultrathin Quantum Dot Display Integrated with Wearable Electronics.

PubMed

Kim, Jaemin; Shim, Hyung Joon; Yang, Jiwoong; Choi, Moon Kee; Kim, Dong Chan; Kim, Junhee; Hyeon, Taeghwan; Kim, Dae-Hyeong

2017-10-01

An ultrathin skin-attachable display is a critical component for an information output port in next-generation wearable electronics. In this regard, quantum dot (QD) light-emitting diodes (QLEDs) offer unique and attractive characteristics for future displays, including high color purity with narrow bandwidths, high electroluminescence (EL) brightness at low operating voltages, and easy processability. Here, ultrathin QLED displays that utilize a passive matrix to address individual pixels are reported. The ultrathin thickness (≈5.5 µm) of the QLED display enables its conformal contact with the wearer's skin and prevents its failure under vigorous mechanical deformation. QDs with relatively thick shells are employed to improve EL characteristics (brightness up to 44 719 cd m -2 at 9 V, which is the record highest among wearable LEDs reported to date) by suppressing the nonradiative recombination. Various patterns, including letters, numbers, and symbols can be successfully visualized on the skin-mounted QLED display. Furthermore, the combination of the ultrathin QLED display with flexible driving circuits and wearable sensors results in a fully integrated QLED display that can directly show sensor data. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanowire decorated, ultra-thin, single crystalline silicon for photovoltaic devices.

PubMed

Aurang, Pantea; Turan, Rasit; Unalan, Husnu Emrah

2017-10-06

Reducing silicon (Si) wafer thickness in the photovoltaic industry has always been demanded for lowering the overall cost. Further benefits such as short collection lengths and improved open circuit voltages can also be achieved by Si thickness reduction. However, the problem with thin films is poor light absorption. One way to decrease optical losses in photovoltaic devices is to minimize the front side reflection. This approach can be applied to front contacted ultra-thin crystalline Si solar cells to increase the light absorption. In this work, homojunction solar cells were fabricated using ultra-thin and flexible single crystal Si wafers. A metal assisted chemical etching method was used for the nanowire (NW) texturization of ultra-thin Si wafers to compensate weak light absorption. A relative improvement of 56% in the reflectivity was observed for ultra-thin Si wafers with the thickness of 20 ± 0.2 μm upon NW texturization. NW length and top contact optimization resulted in a relative enhancement of 23% ± 5% in photovoltaic conversion efficiency.

Antiferromagnetic exchange and magnetoresistance enhancement in ultrathin Co-Re sandwiches

NASA Astrophysics Data System (ADS)

Freitas, P. P.; Melo, L. V.; Trindade, I.; From, M.

1992-10-01

Co-Re ultrathin sandwiches were prepared that show antiferromagnetic coupling and enhanced saturation magnetoresistance for Re spacer thicknesses below 9 Å. A field of 2.5 kOe is needed to saturate the antiferromagnetically coupled Co layers. These results are similar to those found in Co-Re superlattices.

V-doped SnS2: a new intermediate band material for a better use of the solar spectrum.

PubMed

Wahnón, Perla; Conesa, José C; Palacios, Pablo; Lucena, Raquel; Aguilera, Irene; Seminovski, Yohanna; Fresno, Fernando

2011-12-07

Intermediate band materials can boost photovoltaic efficiency through an increase in photocurrent without photovoltage degradation thanks to the use of two sub-bandgap photons to achieve a full electronic transition from the valence band to the conduction band of a semiconductor structure. After having reported in previous works several transition metal-substituted semiconductors as able to achieve the electronic structure needed for this scheme, we propose at present carrying out this substitution in sulfides that have bandgaps of around 2.0 eV and containing octahedrally coordinated cations such as In or Sn. Specifically, the electronic structure of layered SnS(2) with Sn partially substituted by vanadium is examined here with first principles quantum methods and seen to give favourable characteristics in this respect. The synthesis of this material in nanocrystalline powder form is then undertaken and achieved using solvothermal chemical methods. The insertion of vanadium in SnS(2) is found to produce an absorption spectrum in the UV-Vis-NIR range that displays a new sub-bandgap feature in agreement with the quantum calculations. A photocatalytic reaction-based test verifies that this sub-bandgap absorption produces highly mobile electrons and holes in the material that may be used for the solar energy conversion, giving experimental support to the quantum calculations predictions.

Sympathetic neural activation does not mediate heart rate variability during repeated brief umbilical cord occlusions in near-term fetal sheep.

PubMed

Lear, Christopher A; Galinsky, Robert; Wassink, Guido; Mitchell, Clinton J; Davidson, Joanne O; Westgate, Jennifer A; Bennet, Laura; Gunn, Alistair J

2016-03-01

Changes in fetal heart rate variability (FHRV) and ST segment elevation (measured as the T/QRS ratio) are used to evaluate fetal adaptation to labour. The sympathetic nervous system (SNS) is an important contributor to FHRV under healthy normoxic conditions, and is critical for rapid support of blood pressure during brief labour-like asphyxia. However, although it has been assumed that SNS activity contributes to FHRV during labour; this has never been tested, and it is unclear whether the SNS contributes to the rapid increase in T/QRS ratio during brief asphyxia. Thirteen chronically instrumented fetal sheep at 0.85 of gestation received either chemical sympathectomy with 6-hydroxydopamine (6-OHDA; n = 6) or sham treatment (control; n = 7), followed 4-5 days later by 2 min episodes of complete umbilical cord occlusion repeated every 5 min for up to 4 h, or until mean arterial blood pressure fell to <20 mmHg for two successive occlusions. FHRV was decreased before occlusions in the 6-OHDA group (P < 0.05) and 2-4.5 h during recovery after occlusions (P < 0.05) compared to the control group. During each occlusion there was a rapid increase in T/QRS ratio. Between successive occlusions the T/QRS ratio rapidly returned to baseline, and FHRV increased above baseline in both groups (P < 0.05), with no significant effect of sympathectomy on FHRV or T/QRS ratio. In conclusion, these data show that SNS activity does not mediate the increase in FHRV between repeated episodes of brief umbilical cord occlusion or the transient increase in T/QRS ratio during occlusions. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Online Social Networking and Mental Health

PubMed Central

2014-01-01

Abstract During the past decade, online social networking has caused profound changes in the way people communicate and interact. It is unclear, however, whether some of these changes may affect certain normal aspects of human behavior and cause psychiatric disorders. Several studies have indicated that the prolonged use of social networking sites (SNS), such as Facebook, may be related to signs and symptoms of depression. In addition, some authors have indicated that certain SNS activities might be associated with low self-esteem, especially in children and adolescents. Other studies have presented opposite results in terms of positive impact of social networking on self-esteem. The relationship between SNS use and mental problems to this day remains controversial, and research on this issue is faced with numerous challenges. This concise review focuses on the recent findings regarding the suggested connection between SNS and mental health issues such as depressive symptoms, changes in self-esteem, and Internet addiction. PMID:25192305

Snaps, Selfies, and Shares: How Three Popular Social Media Platforms Contribute to the Sociocultural Model of Disordered Eating Among Young Women.

PubMed

Saunders, Jessica F; Eaton, Asia A

2018-06-01

The current study aimed to integrate and test the sociocultural model of disordered eating with theories explaining the impact of mass media on the development of disordered eating for users of three popular social networking platforms. Young women social networking site (SNS) users (age 18-24) who had never received an eating disorder diagnosis (N = 637) completed questions capturing their SNS gratifications and usage, body surveillance, social comparisons, body dissatisfaction, and eating pathology. Measures were administered in one online session. Model relationships were similar across users of all three SNS platforms: Facebook, Instagram, and Snapchat. Users of all platforms demonstrated a significant positive relationship between upward comparisons and disordered eating outcomes, and between body surveillance and disordered eating outcomes, although differences between models did emerge. Empirical findings support extending the sociocultural model of disordered eating to include SNS uses and gratifications.

The use of social networking services and their relationship with the big five personality model and job satisfaction in Korea.

PubMed

Kim, Hyondong; Chung, Yang Woon

2014-10-01

Social networking services (SNSs) have been garnering attention from society due to their recent rapid growth. This study examines whether SNS use can affect the relationship between the Big Five personality model and individual job satisfaction. Based on a sample of 1,452 workers in Korea, the results of this study indicate that the Big Five personality model (extroversion, agreeableness, and neuroticism) was significantly related to individual job satisfaction. Further, SNS use moderated the relationship between extroversion and neuroticism with individual job satisfaction. Also, SNS use was found to increase job satisfaction of Korean workers who are more extroverted, while it also affected job satisfaction of Korean workers with low agreeableness. As SNS use plays an important role in the workplace, it is necessary to realize and appreciate the importance of SNSs in shaping and promoting job satisfaction of working individuals.

Social networking sites: a clinical dilemma?

PubMed

Maughan, Daniel Lawrence; Economou, Alexis

2015-02-01

Social networking sites (SNS) are having an increasing influence on patients' lives and doctors are far from certain about how to deal with this new challenge. In our literature search, we could find no research on how doctors could engage positively with SNS to improve patient outcomes or create more patient-led care. We need to acknowledge the fact that a review of a patient's SNS page has the potential to enhance assessment and management, particularly where a corroborant history is hard to attain. As doctors, we need to think clearly about how to adapt our practice in light of this new form of communication; in particular, whether there is a case for engaging with SNS to improve patient care. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Online social networking and mental health.

PubMed

Pantic, Igor

2014-10-01

During the past decade, online social networking has caused profound changes in the way people communicate and interact. It is unclear, however, whether some of these changes may affect certain normal aspects of human behavior and cause psychiatric disorders. Several studies have indicated that the prolonged use of social networking sites (SNS), such as Facebook, may be related to signs and symptoms of depression. In addition, some authors have indicated that certain SNS activities might be associated with low self-esteem, especially in children and adolescents. Other studies have presented opposite results in terms of positive impact of social networking on self-esteem. The relationship between SNS use and mental problems to this day remains controversial, and research on this issue is faced with numerous challenges. This concise review focuses on the recent findings regarding the suggested connection between SNS and mental health issues such as depressive symptoms, changes in self-esteem, and Internet addiction.

Magnetometry with Low-Resistance Proximity Josephson Junction

NASA Astrophysics Data System (ADS)

Jabdaraghi, R. N.; Peltonen, J. T.; Golubev, D. S.; Pekola, J. P.

2018-06-01

We characterize a niobium-based superconducting quantum interference proximity transistor (Nb-SQUIPT) and its key constituent formed by a Nb-Cu-Nb SNS weak link. The Nb-SQUIPT and SNS devices are fabricated simultaneously in two separate lithography and deposition steps, relying on Ar ion cleaning of the Nb contact surfaces. The quality of the Nb-Cu interface is characterized by measuring the temperature-dependent equilibrium critical supercurrent of the SNS junction. In the Nb-SQUIPT device, we observe a maximum flux-to-current transfer function value of about 55 nA/Φ_0 in the sub-gap regime of bias voltages. This results in suppression of power dissipation down to a few fW. Low-bias operation of the device with a relatively low probe junction resistance decreases the dissipation by up to two orders of magnitude compared to a conventional device based on an Al-Cu-Al SNS junction and an Al tunnel probe (Al-SQUIPT).

Ultrathin Bi2WO6 nanosheet decorated with Pt nanoparticles for efficient formaldehyde removal at room temperature

NASA Astrophysics Data System (ADS)

Sun, Dong; Le, Yao; Jiang, Chuanjia; Cheng, Bei

2018-05-01

Two-dimensional (2D) ultrathin bismuth tungstate (Bi2WO6) nanosheets (BWO-NS) with a thickness of approximately 4.0 nm were synthesized by a one-step hydrothermal method, and decorated with platinum (Pt) nanoparticles (NPs) via an impregnation/borohydride-reduction approach. The as-prepared ultrathin Pt-BWO-NS exhibited superior catalytic activity for removing gaseous formaldehyde (HCHO) at ambient temperature, in comparison with bulk counterpart with Bi2WO6 sheet thickness of tens of nanometers. The ultrathin structure endowed the Pt-BWO-NS sample with larger specific surface area, which can provide abundant surface active sites for HCHO adsorption and facilitate the homogeneous dispersion of Pt NPs. X-ray photoelectron spectroscopy and hydrogen temperature-programmed reduction analyses revealed the interaction between the Bi2WO6 support and Pt species, which is crucial for activating surface oxygen atoms to participate in the catalytic HCHO oxidation process. By conducting in situ diffuse reflectance infrared Fourier transform spectroscopy under different atmospheres, i.e., gaseous HCHO in nitrogen or oxygen (O2), the reaction mechanism and the role of O2 were elucidated, with dioxymethylene, formate and linearly adsorbed carbon monoxide identified as the main reaction intermediates. This study may provide new enlightenment on fabricating novel 2D nanomaterials for efficient indoor air purification and potentially other environmental applications.

Achieving Ohmic Contact for High-quality MoS2 Devices on Hexagonal Boron Nitride

NASA Astrophysics Data System (ADS)

Cui, Xu

MoS2, among many other transition metal dichalcogenides (TMDCs), holds great promise for future applications in nano-electronics, opto-electronics and mechanical devices due to its ultra-thin nature, flexibility, sizable band-gap, and unique spin-valley coupled physics. However, there are two main challenges that hinder careful study of this material. Firstly, it is hard to achieve Ohmic contacts to mono-layer MoS2, particularly at low temperatures (T) and low carrier densities. Secondly, materials' low quality and impurities introduced during the fabrication significantly limit the electron mobility of mono- and few-layer MoS2 to be substantially below theoretically predicted limits, which has hampered efforts to observe its novel quantum transport behaviours. Traditional low work function metals doesn't necessary provide good electron injection to thin MoS2 due to metal oxidation, Fermi level pinning, etc. To address the first challenge, we tried multiple contact schemes and found that mono-layer hexagonal boron nitride (h-BN) and cobalt (Co) provide robust Ohmic contact. The mono-layer spacer serves two advantageous purposes: it strongly interacts with the transition metal, reducing its work function by over 1 eV; and breaks the metal-TMDCs interaction to eliminate the interfacial states that cause Fermi level pinning. We measure a flat-band Schottky barrier of 16 meV, which makes thin tunnel barriers upon doping the channels, and thus achieve low-T contact resistance of 3 kohm.um at a carrier density of 5.3x10. 12/cm. 2. Similar to graphene, eliminating all potential sources of disorder and scattering is the key to achieving high performance in MoS2 devices. We developed a van der Waals heterostructure device platform where MoS2 layers are fully encapsulated within h-BN and electrically contacted in a multi-terminal geometry using gate-tunable graphene electrodes. The h-BN-encapsulation provides excellent protection from environmental factors, resulting in highly stable device performance, even at elevated temperatures. Both optical and electrical characterization confirms our high quality devices, including an ultra-clean interface, a record-high Hall mobility reaching 34,000 cm. 2/Vs, and first observation of Shubnikov–de Haas oscillations. The development of Ohmic contact and fabrication of high quality devices are critical to MoS2 application and studying its intrinsic properties. Therefore, the progress made in this work will facilitate efforts to study novel physical phenomena of MoS2 that were not accessible before.

Ultrathin cerium orthovanadate nanobelts for high-performance flexible all-solid-state asymmetric supercapacitors.

PubMed

He, Junzhi; Zhao, Junhong; Run, Zhen; Sun, Mengjun; Pang, Huan

2015-02-01

Ultrathin CeVO4 nanobelts were successfully synthesized by a hydrothermal method. The thickness of a single nanobelt is about 2.4 nm, which can effectively shorten the ion diffusion and fasten the charge pathway. More importantly, ultrathin CeVO4 nanobelts and graphene are easily assembled as a flexible all-solid-state asymmetric device, which shows a highly flexible property and achieves a maximum energy density of 0.78 mW h cm(-3) and a high life cycle of >6000 cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

β-Hydroxybutyrate modulates N-type calcium channels in rat sympathetic neurons by acting as an agonist for the G-protein-coupled receptor FFA3.

PubMed

Won, Yu-Jin; Lu, Van B; Puhl, Henry L; Ikeda, Stephen R

2013-12-04

Free fatty acids receptor 3 (FFA3, GPR41) and 2 (FFA2, GPR43), for which the short-chain fatty acids (SCFAs) acetate and propionate are agonist, have emerged as important G-protein-coupled receptors influenced by diet and gut flora composition. A recent study (Kimura et al., 2011) demonstrated functional expression of FFA3 in the rodent sympathetic nervous system (SNS) providing a potential link between nutritional status and autonomic function. However, little is known of the source of endogenous ligands, signaling pathways, or effectors in sympathetic neurons. In this study, we found that FFA3 and FFA2 are unevenly expressed in the rat SNS with higher transcript levels in prevertebral (e.g., celiac-superior mesenteric and major pelvic) versus paravertebral (e.g., superior cervical and stellate) ganglia. FFA3, whether heterologously or natively expressed, coupled via PTX-sensitive G-proteins to produce voltage-dependent inhibition of N-type Ca(2+) channels (Cav2.2) in sympathetic neurons. In addition to acetate and propionate, we show that β-hydroxybutyrate (BHB), a metabolite produced during ketogenic conditions, is also an FFA3 agonist. This contrasts with previous interpretations of BHB as an antagonist at FFA3. Together, these results indicate that endogenous BHB levels, especially when elevated under certain conditions, such as starvation, diabetic ketoacidosis, and ketogenic diets, play a potentially important role in regulating the activity of the SNS through FFA3.

Ultrathin gas permeable oxide membranes for chemical sensing: Nanoporous Ta 2O 5 test study

DOE PAGES

Imbault, Alexander; Wang, Yue; Kruse, Peter; ...

2015-09-25

Conductometric gas sensors made of gas permeable metal oxide ultrathin membranes can combine the functions of a selective filter, preconcentrator, and sensing element and thus can be particularly promising for the active sampling of diluted analytes. Here we report a case study of the electron transport and gas sensing properties of such a membrane made of nanoporous Ta 2O 5. These membranes demonstrated a noticeable chemical sensitivity toward ammonia, ethanol, and acetone at high temperatures above 400 °C. Furthermore, different from traditional thin films, such gas permeable, ultrathin gas sensing elements can be made suspended enabling advanced architectures of ultrasensitivemore » analytical systems operating at high temperatures and in harsh environments.« less

Influence of vacuum annealing on the properties of Cu2SnS3 thin films using low cost ultrasonic spray pyrolysis

NASA Astrophysics Data System (ADS)

Rahaman, Sabina; Sunil, M. Anantha; Shaik, Habibuddin; Ghosh, Kaustab

2018-05-01

Deposition of Cu2SnS3 (CTS) thin films is successfully carried out on soda lime glass substrate using low cost ultrasonic spray pyrolysis technique. Vacuum annealing of CTS films is carried out at different temperatures 350°C, 400°C and 450°C. The present work is to study the effect of annealing temperature on the crystal structure, surface morphology and optical properties of CTS thin films. Structural studies confirm the formation of CTS phase. Raman analysis is carried out to study presence of defects with annealing temperature. Optical studies confirm that film prepared at 450°C temperature is suitable as absorber material for photovoltaic applications.

Discovery of a hexagonal ultradense hydrous phase in (Fe,Al)OOH

NASA Astrophysics Data System (ADS)

Zhang, Li; Yuan, Hongsheng; Meng, Yue; Mao, Ho-kwang

2018-03-01

A deep lower-mantle (DLM) water reservoir depends on availability of hydrous minerals which can store and transport water into the DLM without dehydration. Recent discoveries found hydrous phases AlOOH (Z = 2) with a CaCl2-type structure and FeOOH (Z = 4) with a cubic pyrite-type structure stable under the high-pressure–temperature (P-T) conditions of the DLM. Our experiments at 107–136 GPa and 2,400 K have further demonstrated that (Fe,Al)OOH is stabilized in a hexagonal lattice. By combining powder X-ray-diffraction techniques with multigrain indexation, we are able to determine this hexagonal hydrous phase with a = 10.5803(6) Å and c = 2.5897(3) Å at 110 GPa. Hexagonal (Fe,Al)OOH can transform to the cubic pyrite structure at low T with the same density. The hexagonal phase can be formed when δ-AlOOH incorporates FeOOH produced by reaction between water and Fe, which may store a substantial quantity of water in the DLM.