Spontaneous nano-gap formation in Ag film using NaCl sacrificial layer for Raman enhancement

NASA Astrophysics Data System (ADS)

Min, Kyungchan; Jeon, Wook Jin; Kim, Youngho; Choi, Jae-Young; Yu, Hak Ki

2018-03-01

We report the method of fabrication of nano-gaps (known as hot spots) in Ag thin film using a sodium chloride (NaCl) sacrificial layer for Raman enhancement. The Ag thin film (20-50 nm) on the NaCl sacrificial layer undergoes an interfacial reaction due to the AgCl formed at the interface during water molecule intercalation. The intercalated water molecules can dissolve the NaCl molecules at interfaces and form the ionic state of Na+ and Cl-, promoting the AgCl formation. The Ag atoms can migrate by the driving force of this interfacial reaction, resulting in the formation of nano-size gaps in the film. The surface-enhanced Raman scattering activity of Ag films with nano-size gaps has been investigated using Raman reporter molecules, Rhodamine 6G (R6G).

Microstructures and fatigue life of SnAgCu solder joints bearing Nano-Al particles in QFP devices

NASA Astrophysics Data System (ADS)

Zhang, Liang; Fan, Xi-ying; Guo, Yong-huan; He, Cheng-wen

2014-05-01

Microstructures and fatigue life of SnAgCu and SnAgCu bearing nano-Al particles in QFP (Quad flat package) devices were investigated, respectively. Results show that the addition of nano-Al particles into SnAgCu solder can refine the microstructures of matrix microstructure. Moreover, the nano-Al particles present in the solder matrix, act as obstacles which can create a back stress, resisting the motion of dislocations. In QFP device, it is found that the addition of nano-Al particles can increase the fatigue life by 32% compared with the SnAgCu solder joints during thermal cycling loading.

Pool boiling of water on nano-structured micro wires at sub-atmospheric conditions

NASA Astrophysics Data System (ADS)

Arya, Mahendra; Khandekar, Sameer; Pratap, Dheeraj; Ramakrishna, S. Anantha

2016-09-01

Past decades have seen active research in enhancement of boiling heat transfer by surface modifications. Favorable surface modifications are expected to enhance boiling efficiency. Several interrelated mechanisms such as capillarity, surface energy alteration, wettability, cavity geometry, wetting transitions, geometrical features of surface morphology, etc., are responsible for change in the boiling behavior of modified surfaces. Not much work is available on pool boiling at low pressures on microscale/nanoscale geometries; low pressure boiling is attractive in many applications wherein low operating temperatures are desired for a particular working fluid. In this background, an experimental setup was designed and developed to investigate the pool boiling performance of water on (a) plain aluminum micro wire (99.999 % pure) and, (b) nano-porous alumina structured aluminum micro wire, both having diameter of 250 µm, under sub-atmospheric pressure. Nano-structuring on the plain wire surface was achieved via anodization. Two samples, A and B of anodized wires, differing by the degree of anodization were tested. The heater length scale (wire diameter) was much smaller than the capillary length scale. Pool boiling characteristics of water were investigated at three different sub-atmospheric pressures of 73, 123 and 199 mbar (corresponding to T sat = 40, 50 and 60 °C). First, the boiling characteristics of plain wire were measured. It was noticed that at sub-atmospheric pressures, boiling heat transfer performance for plain wire was quite low due to the increased bubble sizes and low nucleation site density. Subsequently, boiling performance of nano-structured wires (both Sample A and Sample B) was compared with plain wire and it was noted that boiling heat transfer for the former was considerably enhanced as compared to the plain wire. This enhancement is attributed to increased nucleation site density, change in wettability and possibly due to enhanced pore scale

A model of optical trapping cold atoms using a metallic nano wire with surface plasmon effect

NASA Astrophysics Data System (ADS)

Thi Phuong Lan, Nguyen; Thi Nga, Do; Viet, Nguyen Ai

2016-06-01

In this work, we construct a new model of optical trapping cold atoms with a metallic nano wire by using surface plasmon effect generated by strong field of laser beams. Using the skin effect, we send a strong oscillated electromagnetic filed through the surface of a metallic nano wire. The local field generated by evanescent effect creates an effective attractive potential near the surface of metallic nano wires. The consideration of some possible boundary and frequency conditions might lead to non-trivial bound state solution for a cold atom. We discus also the case of the laser reflection optical trap with shell-core design, and compare our model with another recent schemes of cold atom optical traps using optical fibers and carbon nanotubes.

Effect of sheath material and reaction overpressure on Ag protrusions into the TiO2 insulation coating of Bi-2212 round wire

NASA Astrophysics Data System (ADS)

Hossain, I.; Jiang, J.; Matras, M.; Trociewitz, U. P.; Lu, J.; Kametani, F.; Larbalestier, D.; Hellstrom, E.

2017-12-01

In order to develop a high current density in coils, Bi-2212 wires must be electrically discrete in tight winding packs. It is vital to use an insulating layer that is thin, fulfils the dielectric requirements, and can survive the heat treatment whose maximum temperature reaches 890 °C in oxygen. A thin (20-30 µm) ceramic coating could be better as the insulating layer compared to alumino-silicate braided fiber insulation, which is about 150 μm thick and reacts with the Ag sheathed Bi-2212 wire during heat treatment. At present, TiO2 seems to be the most viable ceramic material for such a thin insulation because it is chemically compatible with Ag and Bi-2212 and its sintering temperature is lower than the maximum temperature used for the Bi-2212 heat treatment. However, recent tests of a large Bi-2212 coil insulated only with TiO2 showed severe electrical shorting between the wires after over pressure heat treatment (OPHT). The origin of the shorting was frequent silver protrusions into the porous TiO2 layer that electrically connected adjacent Bi-2212 wires. To understand the mechanism of this unexpected behaviour, we investigated the effect of sheath material and hydrostatic pressure on Ag protrusions. We found that Ag protrusions occur only when TiO2-insulated Ag-0.2%Mg sheathed wire (Ag(Mg) wire) undergoes OPHT at 50 bar. No Ag protrusions were observed when the TiO2-insulated Ag(Mg) wire was processed at 1 bar. The TiO2-insulated wires sheathed with pure Ag that underwent 50 bar OPHT were also free from Ag protrusions. A key finding is that the Ag protrusions from the Ag(Mg) sheath actually contain no MgO, suggesting that local depletion of MgO facilitates local, heterogeneous deformation of the sheath under hydrostatic overpressure. Our study also suggests that predensifying the Ag(Mg) wire before insulating it with TiO2 and doing the final OPHT can potentially limit Ag protrusions.

Micro/nano-particle decorated metal wire for cutting soft matter

NASA Astrophysics Data System (ADS)

Zhang, Wei; Feng, Liang-liang; Wu, Fan; Zhang, Run-run; Wu, Cheng-wei

2016-09-01

To cut soft materials such as biological tissues with minimal damage and reduced positional error is highly desired in medical surgery and biomechanics. After years of natural selection and evolution, mosquitoes have acquired the ability to insert their proboscises into human skin with astonishingly tiny forces. This can be associated with the unique structure of their proboscises, with micro/nano sawteeth, and the distinctive insertion manner: high frequency reciprocating saw cutting. Inspired by these, this communication describes the successful implantation of metal oxide particles onto molybdenum wire surfaces through a sol-calcination process, to form a biomimetic sawblade with a high density of micro/nano saw teeth, where the acidification is essential in terms of generating active anchoring sites on the wire. When used as a sawblade in conjunction with reciprocating action to cut the viscoelastic gel, both the cut-in force and cut-in displacement could be decreased substantially. The cutting speed and frequency of reciprocating action are important operating parameters influencing cut-in force.

Nano-Nucleation Characteristic of Cu-Ag Alloy Directly Electrodeposited on W Diffusion Barrier for Microelectronic Device Interconnect.

PubMed

Kim, Kang O; Kim, Sunjung

2016-05-01

Cu-Ag alloy interconnect is promising for ultra-large-scale integration (ULSI) microelectronic system of which device dimension keeps shrinking. In this study, seedless electrodeposition of Cu-Ag alloy directly on W diffusion barrier as interconnect technology is presented in respect of nano-nucleation control. Chemical equilibrium state of electrolyte was fundamentally investigated according to the pH of electrolyte because direct nano-nucleation of Cu-Ag alloy on W surface is challenging. Chelation behavior of Cu2+ and Ag+ ions with citrate (Cit) and ammonia ligands was dependent on the pH of electrolyte. The amount and kind of Cu- and Ag-based complexes determine the deposition rate, size, elemental composition, and surface morphology of Cu-Ag alloy nano-nuclei formed on W surface.

Report: Discussion on the development of nano Ag/TiO2 coating bracket and its antibacterial property and biocompatibility in orthodontic treatment.

PubMed

Zhang, Ronghe; Zhang, Weiwei; Bai, Xueyan; Song, Xiaotong; Wang, Chunyan; Gao, Xinxin; Tian, Xubiao; Liu, Fengzhen

2015-03-01

This paper aims to explore the antibacterial property of nano Ag/TiO2 coating bracket for the common bacteria in oral cavity, and discuss its biocompatibility. Micro morphology in the surface of nano Ag/TiO2 coating bracket was detected by scanning electron microscope (SEM), and surface roughness of ordinary mental bracket, nano TiO2 coating bracket and nano Ag/TiO2 coating bracket were measured. First, antibacterial property of nano Ag/TiO2 coating bracket on the common bacteria in oral cavity was studied by sticking membrane method. Secondly, bonding strength of nano TiO2 coating and nano Ag/TiO2 coating bracket in groups were detected by scratching test. The result showed that, the synthetic nano Ag/TiO2 coating was nanogranular films with rigorous organizational structure, presenting as smooth and clean surface, and antibacterial rate of nano Ag/TiO2 coating for the common bacteria in oral cavity for 20 min was more than 79% in the dark. All the findings suggested that, nano Ag/TiO2 coating bracket not only has antibacterial effect but also has good biocompatibility, therefore, it can satisfy the clinical request of orthodontic treatment.

Optimal synthesis and characterization of Ag nanofluids by electrical explosion of wires in liquids

PubMed Central

2011-01-01

Silver nanoparticles were produced by electrical explosion of wires in liquids with no additive. In this study, we optimized the fabrication method and examined the effects of manufacturing process parameters. Morphology and size of the Ag nanoparticles were determined using transmission electron microscopy and field-emission scanning electron microscopy. Size and zeta potential were analyzed using dynamic light scattering. A response optimization technique showed that optimal conditions were achieved when capacitance was 30 μF, wire length was 38 mm, liquid volume was 500 mL, and the liquid type was deionized water. The average Ag nanoparticle size in water was 118.9 nm and the zeta potential was -42.5 mV. The critical heat flux of the 0.001-vol.% Ag nanofluid was higher than pure water. PMID:21711757

Micro-structure and properties of Cu-0.5 wt%Ag alloy fine wires with severe cold plastic deformation treatment

NASA Astrophysics Data System (ADS)

Shu-sen, Wang; Yuan-wang, Zhang; Da-wei, Yao

2018-04-01

In this work, the Cu-0.5 wt% Ag alloy was prepared and then sold solution treated at 760 °C for 4 h and aged at 400 °C for 4 h. The severe cold plastic deformation treatment with a maximum true strain of 11.48 was applied to obtain the Cu-0.5 wt%Ag fine wires with the diameter of 0.087 mm. Then the fine wires were given eight intermediate heat treatments at 300 °C–350 °C for 10–60 min. Properties of the fine wires with different annealing heat treatments were analyzed, results showed that after the annealing process of 350 °C, 20 min was applied to Cu-0.5 wt% Ag fine wires, their conductivity, tensile strength and elongation could reach 98.6%IACS, 367 MPa and 8%, respectively. This demonstrated that the Cu-0.5 wt% Ag processes high strength and high conductivity properties and was a promising conductive material.

Fabrication and characterization of gold nano-wires templated on virus-like arrays of tobacco mosaic virus coat proteins

NASA Astrophysics Data System (ADS)

Wnęk, M.; Górzny, M. Ł.; Ward, M. B.; Wälti, C.; Davies, A. G.; Brydson, R.; Evans, S. D.; Stockley, P. G.

2013-01-01

The rod-shaped plant virus tobacco mosaic virus (TMV) is widely used as a nano-fabrication template, and chimeric peptide expression on its major coat protein has extended its potential applications. Here we describe a simple bacterial expression system for production and rapid purification of recombinant chimeric TMV coat protein carrying C-terminal peptide tags. These proteins do not bind TMV RNA or form disks at pH 7. However, they retain the ability to self-assemble into virus-like arrays at acidic pH. C-terminal peptide tags in such arrays are exposed on the protein surface, allowing interaction with target species. We have utilized a C-terminal His-tag to create virus coat protein-templated nano-rods able to bind gold nanoparticles uniformly. These can be transformed into gold nano-wires by deposition of additional gold atoms from solution, followed by thermal annealing. The resistivity of a typical annealed wire created by this approach is significantly less than values reported for other nano-wires made using different bio-templates. This expression construct is therefore a useful additional tool for the creation of chimeric TMV-like nano-rods for bio-templating.

Nano-scaled Pt/Ag/Ni/Au contacts on p-type GaN for low contact resistance and high reflectivity.

PubMed

Kwon, Y W; Ju, I C; Kim, S K; Choi, Y S; Kim, M H; Yoo, S H; Kang, D H; Sung, H K; Shin, K; Ko, C G

2011-07-01

We synthesized the vertical-structured LED (VLED) using nano-scaled Pt between p-type GaN and Ag-based reflector. The metallization scheme on p-type GaN for high reflectance and low was the nano-scaled Pt/Ag/Ni/Au. Nano-scaled Pt (5 A) on Ag/Ni/Au exhibited reasonably high reflectance of 86.2% at the wavelength of 460 nm due to high transmittance of light through nano-scaled Pt (5 A) onto Ag layer. Ohmic behavior of contact metal, Pt/Ag/Ni/Au, to p-type GaN was achieved using surface treatments of p-type GaN prior to the deposition of contact metals and the specific contact resistance was observed with decreasing Pt thickness of 5 A, resulting in 1.5 x 10(-4) ohms cm2. Forward voltages of Pt (5 A)/Ag/Ni contact to p-type GaN showed 4.19 V with the current injection of 350 mA. Output voltages with various thickness of Pt showed the highest value at the smallest thickness of Pt due to its high transmittance of light onto Ag, leading to high reflectance. Our results propose that nano-scaled Pt/Ag/Ni could act as a promising contact metal to p-type GaN for improving the performance of VLEDs.

Formation of Bi2Sr2CaCu2O x /Ag multifilamentary metallic precursor powder-in-tube wires

NASA Astrophysics Data System (ADS)

Zhang, Yun; Koch, Carl C.; Schwartz, Justin

2016-12-01

Previously, a metallic precursor (MP) approach to synthesizing Bi2Sr2CaCu2O x (Bi2212), with a homogeneous mixture of Bi, Sr, Ca, Cu and Ag was produced by mechanical alloying. Here, Bi2212/Ag round multifilamentary wire is manufactured using a metallic precursor powder-in-tube (MPIT) process. The MP powders were packed into a pure Ag tube in an Ar atmosphere and then sealed. After deformation, multifilamentary round wires and rolled tapes were heat treated in flowing oxygen through three stages: oxidation, conversion and partial-melt processing (PMP). Processing-microstructure-property relationships on 20-50 mm long multifilamentary round wires and rolled tapes were studied extensively. It is shown that conventional wire deformation processes, optimized for oxide-powder-in-tube wires, are not effective for deforming MPIT wires, and that as with prior studies of MPIT Bi2Sr2Ca2Cu3O y conductors, hot extrusion is required for obtaining a multifilamentary structure with fine filaments. As a result, the Bi2212 MPIT wires reported here have low engineering critical current density. Nonetheless, by focusing on sections of wires that remain intact after deformation, it is also shown that the first heat treatment stage, the oxidation stage, plays a crucial role in chemical homogeneity, phase transformation, and microstructural evolution and three reaction pathways for MP oxidation are presented. Furthermore, it is found the Bi2212 grain alignment within an MPIT filament is significantly different from that found in OPIT filaments after PMP, indicating the formation of highly dense filaments containing Bi2212 fine grains and Ag particles before PMP aids the formation of large, c-axis textured Bi2212 filaments during PMP. These results show that, with improved wire deformation, high critical current density may be obtained via a MPIT process.

Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

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

Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr; Kim, Min-Yi

2015-12-15

We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs). The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, themore » TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.« less

In Planta Synthesis of Designer-Length Tobacco Mosaic Virus-Based Nano-Rods That Can Be Used to Fabricate Nano-Wires.

PubMed

Saunders, Keith; Lomonossoff, George P

2017-01-01

We have utilized plant-based transient expression to produce tobacco mosaic virus (TMV)-based nano-rods of predetermined lengths. This is achieved by expressing RNAs containing the TMV origin of assembly sequence (OAS) and the sequence of the TMV coat protein either on the same RNA molecule or on two separate constructs. We show that the length of the resulting nano-rods is dependent upon the length of the RNA that possesses the OAS element. By expressing a version of the TMV coat protein that incorporates a metal-binding peptide at its C-terminus in the presence of RNA containing the OAS we have been able to produce nano-rods of predetermined length that are coated with cobalt-platinum. These nano-rods have the properties of defined-length nano-wires that make them ideal for many developing bionanotechnological processes.

In Planta Synthesis of Designer-Length Tobacco Mosaic Virus-Based Nano-Rods That Can Be Used to Fabricate Nano-Wires

PubMed Central

Saunders, Keith; Lomonossoff, George P.

2017-01-01

We have utilized plant-based transient expression to produce tobacco mosaic virus (TMV)-based nano-rods of predetermined lengths. This is achieved by expressing RNAs containing the TMV origin of assembly sequence (OAS) and the sequence of the TMV coat protein either on the same RNA molecule or on two separate constructs. We show that the length of the resulting nano-rods is dependent upon the length of the RNA that possesses the OAS element. By expressing a version of the TMV coat protein that incorporates a metal-binding peptide at its C-terminus in the presence of RNA containing the OAS we have been able to produce nano-rods of predetermined length that are coated with cobalt-platinum. These nano-rods have the properties of defined-length nano-wires that make them ideal for many developing bionanotechnological processes. PMID:28878782

Au-Ag-Cu nano-alloys: tailoring of permittivity

NASA Astrophysics Data System (ADS)

Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

2016-04-01

Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective.

The highly efficient photocatalytic and light harvesting property of Ag-TiO2 with negative nano-holes structure inspired from cicada wings.

PubMed

Zada, Imran; Zhang, Wang; Zheng, Wangshu; Zhu, Yuying; Zhang, Zhijian; Zhang, Jianzhong; Imtiaz, Muhammad; Abbas, Waseem; Zhang, Di

2017-12-08

The negative replica of biomorphic TiO 2 with nano-holes structure has been effectively fabricated directly from nano-nipple arrays structure of cicada wings by using a simple, low-cost and highly effective sol-gel ultrasonic method. The nano-holes array structure was well maintained after calcination in air at 500 °C. The Ag nanoparticles (10 nm-25 nm) were homogeneously decorated on the surface and to the side wall of nano-holes structure. It was observed that the biomorphic Ag-TiO 2 showed remarkable photocatalytic activity by degradation of methyl blue (MB) under UV-vis light irradiation. The biomorphic Ag-TiO 2 with nano-holes structure showed superior photocatalytic activity compared to the biomorphic TiO 2 and commercial Degussa P25. This high-performance photocatalytic activity of the biomorphic Ag-TiO 2 may be attributed to the nano-holes structure, localized surface plasmon resonance (LSPR) property of the Ag nanoparticles, and enhanced electron-hole separation. Moreover, the biomorphic Ag-TiO 2 showed more absorption capability in the visible wavelength range. This work provides a new insight to design such a structure which may lead to a range of novel applications.

Synthesis and antibacterial evaluation of calcinated Ag-doped nano-hydroxyapatite with dispersibility.

PubMed

Furuzono, Tsutomu; Motaharul, Mazumder; Kogai, Yasumichi; Azuma, Yoshinao; Sawa, Yoshiki

2015-05-01

Dispersible hydroxyapatite (HAp) nanoparticles are very useful for applying a monolayer to implantable medical devices using the nano-coating technique. To improve tolerance to infection on implanted medical devices, silver-doped HAp (Ag-HAp) nanoparticles with dispersiblity and crystallinity were synthesized, avoiding calcination-induced sintering, and evaluated for antibacterial activity. The Ca10-xAgx(PO4)6(OH)2 with x = 0 and 0.2 were prepared by wet chemical processing at 100°C. Before calcination at 700°C for 2 h, two kinds of anti-sintering agents, namely a Ca(NO3)2 (Ca salt) and a polyacrylic acid/Ca salt mixture (PAA-Ca), were used. Escherichia coli was used to evaluate the antibacterial activity of the nanopowder. When PAA-Ca was used as an anti-sintering agent in calcination to prepare the dispersible nanoparticles, strong metallic Ag peaks were observed at 38.1° and 44.3° (2θ) in the X-ray diffraction (XRD) profile. However, the Ag peak was barely observed when Ca salt was used alone as the anti-sintering agent. Thus, using Ca salt alone was more effective for preparation of dispersible Ag-HAp than PAA-Ca. The particle average size of Ag-HAp with 0.5 mol% of Ag content was found to be 325 ± 70 nm when the formation of large particleaggregations was prevented, as determined by dynamic light scattering instrument. The antibacterial activity of the Ag-HAp nanoparticles possessing 0.5 mol% against E. coli was greater than 90.0%. Dispersible and crystalline nano Ag-HAp can be obtained by using Ca salt alone as an anti-sintering agent. The nanoparticles showed antibacterial activity.

Structural and dielectric studies on Ag doped nano ZnSnO3

NASA Astrophysics Data System (ADS)

Deepa, K.; Angel, S. Lilly; Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

2018-04-01

Undoped and Ag-doped nano Zinc Stannate (ZSO) ternary oxide were prepared by co-precipitation method. The crystallographic, morphological and optical properties of the synthesized nanoparticles were studied using X-ray diffraction (XRD) and UV-Visible spectroscopy (UV-Vis) and Scanning electron microscopy (SEM). The electrical properties of the synthesized samples were studied by dielectric measurements. Higher concentration Ag doped ZSO nanoparticles exhibit higher dielectric constant at low frequency.

Au-Ag-Cu nano-alloys: tailoring of permittivity

PubMed Central

Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

2016-01-01

Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective. PMID:27118459

Influence of Bi addition on the property of Ag-Bi nano-composite coatings

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

Wang, Yuxin; Tay, See Leng; Zhou, Xiaowei

Silver (Ag) coatings have been widely used in many industry areas due to their excellent conductivity. However, wider applications of Ag coatings have been hindered by their poor mechanical properties. In this research, to improve the mechanical performance, Ag-Bi nano-composite coatings were prepared by a novel ionic co-discharge method. A systematic study of the microstructure, mechanical properties, electrical conductivity and antibacterial behavior of the resulting coating was performed. The results indicated that after adding an appropriate amount of Bi containing solution into the Ag plating solution, Ag-Bi nanoparticles were in-situ formed and distributed uniformly throughout the coating matrix, resulting inmore » a significant improvement in the mechanical properties. The hardness of Ag-Bi coating was increased by 60% compared to that of the pure Ag coating. The corrosion resistance of Ag-Bi coatings was also enhanced. The Ag-Bi coatings prepared in the current study will find a broader application in electronics, jewelry, aerospace and other industries.« less

Influence of Bi addition on the property of Ag-Bi nano-composite coatings

DOE PAGES

Wang, Yuxin; Tay, See Leng; Zhou, Xiaowei; ...

2018-03-26

Silver (Ag) coatings have been widely used in many industry areas due to their excellent conductivity. However, wider applications of Ag coatings have been hindered by their poor mechanical properties. In this research, to improve the mechanical performance, Ag-Bi nano-composite coatings were prepared by a novel ionic co-discharge method. A systematic study of the microstructure, mechanical properties, electrical conductivity and antibacterial behavior of the resulting coating was performed. The results indicated that after adding an appropriate amount of Bi containing solution into the Ag plating solution, Ag-Bi nanoparticles were in-situ formed and distributed uniformly throughout the coating matrix, resulting inmore » a significant improvement in the mechanical properties. The hardness of Ag-Bi coating was increased by 60% compared to that of the pure Ag coating. The corrosion resistance of Ag-Bi coatings was also enhanced. The Ag-Bi coatings prepared in the current study will find a broader application in electronics, jewelry, aerospace and other industries.« less

Transport current density at temperatures up to 25 K of Cu/Ag composite sheathed 122-type tapes and wires

NASA Astrophysics Data System (ADS)

Liu, Shifa; Lin, Kaili; Yao, Chao; Zhang, Xianping; Dong, Chiheng; Wang, Dongliang; Awaji, Satoshi; Kumakura, Hiroaki; Ma, Yanwei

2017-11-01

The fabrication of iron-based superconductors with high transport critical current density (J c) and low cost is a crucial determinant of whether they can be used for practical applications. In this paper, Cu/Ag composite sheathed Sr0.6K0.4Fe2As2 (Sr122) tapes and Ba0.6K0.4Fe2As2 (Ba122) round wires were fabricated via an ex situ powder-in-tube method and heat-treated by the hot pressing and hot isostatic pressing process respectively. In order to thoroughly reveal the application potential of Cu/Ag composite sheathed ‘122’ iron pnictide superconductors, transport J c of tapes and wires in high fields at temperatures up to 25 K was measured. High transport J c of 4.4 × 104 A cm-2 at 4.2 K and 3.6 × 103 A cm-2 at 20 K in 10 T was achieved in Cu/Ag composite sheathed Sr122 tapes. Transport J c of Ba122 wires is 9.4 × 103 A cm-2 at 4.2 K and 1.9 × 103 A cm-2 at 20 K in 10 T. These results demonstrate the great potential of Cu/Ag composite sheathed ‘122’ iron pnictide superconducting tapes and wires for high-field applications at intermediate temperatures around 20 K, which can be easily obtained by using cryocoolers.

Texturization of diamond-wire-sawn multicrystalline silicon wafer using Cu, Ag, or Ag/Cu as a metal catalyst

NASA Astrophysics Data System (ADS)

Wang, Shing-Dar; Chen, Ting-Wei

2018-06-01

In this work, Cu, Ag, or Ag/Cu was used as a metal catalyst to study the surface texturization of diamond-wire-sawn (DWS) multi-crystalline silicon (mc-Si) wafer by a metal-assisted chemical etching (MACE) method. The DWS wafer was first etched by standard HF-HNO3 acidic etching, and it was labeled as AE-DWS wafer. The effects of ratios of Cu(NO3)2:HF, AgNO3:HF, and AgNO3:Cu(NO3)2 on the morphology of AE-DWS wafer were investigated. After the process of MACE, the wafer was treated with a NaF/H2O2 solution. In this process, H2O2 etched the nanostructure, and NaF removed the oxidation layer. The Si {1 1 1} plane was revealed by etching the wafer in a mixture of 0.03 M Cu(NO3)2 and 1 M HF at 55 °C for 2.5 min. These parallel Si {1 1 1} planes replaced some parallel saw marks on the surface of AE-DWS wafers without forming a positive pyramid or an inverted pyramid structure. The main topography of the wafer is comprised of silicon nanowires grown in <1 0 0> direction when Ag or Ag/Cu was used as a metal catalyst. When silicon is etched in a mixed solution of Cu(NO3)2, AgNO3, HF and H2O2 at 55 °C with a concentration ratio of [Cu2+]/[Ag+] of 50 or at 65 °C with a concentration ratio of [Cu2+]/[Ag+] of 33, a quasi-inverted pyramid structure can be obtained. The reflectivity of the AE-DWS wafers treated with MACE is lower than that of the multiwire-slurry-sawn (MWSS) mc-Si wafers treated with traditional HF + HNO3 etching.

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

NASA Astrophysics Data System (ADS)

Kim, Hyo-Joong; Ko, Eun-Hye; Noh, Yong-Jin; Na, Seok-In; Kim, Han-Ki

2016-09-01

Nano-scale surface roughness in transparent ITO films was artificially formed by sputtering a mixed Ag and ITO layer and wet etching of segregated Ag nanoparticles from the surface of the ITO film. Effective removal of self-segregated Ag particles from the grain boundaries and surface of the crystalline ITO film led to a change in only the nano-scale surface morphology of ITO film without changes in the sheet resistance and optical transmittance. A nano-scale rough surface of the ITO film led to an increase in contact area between the hole transport layer and the ITO anode, and eventually increased the hole extraction efficiency in the organic solar cells (OSCs). The heterojunction OSCs fabricated on the ITO anode with a nano-scale surface roughness exhibited a higher power conversion efficiency of 3.320%, than that (2.938%) of OSCs made with the reference ITO/glass. The results here introduce a new method to improve the performance of OSCs by simply modifying the surface morphology of the ITO anodes.

A Full-Visible-Spectrum Invisibility Cloak for Mesoscopic Metal Wires.

PubMed

Kim, Sang-Woo; An, Byeong Wan; Cho, Eunjin; Hyun, Byung Gwan; Moon, Yoon-Jong; Kim, Sun-Kyung; Park, Jang-Ung

2018-06-13

Structured metals can sustain a very large scattering cross-section that is induced by localized surface plasmons, which often has an adverse effect on their use as transparent electrodes in displays, touch screens, and smart windows due to an issue of low clarity. Here, we report a broadband optical cloaking strategy for the network of mesoscopic metal wires with submicrometer to micrometer diameters, which is exploited for manufacturing and application of high-clarity metal-wires-based transparent electrodes. We prepare electrospun Ag wires with 300-1800 nm in diameter and perform a facile surface oxidation process to form Ag/Ag 2 O core/shell heterogeneous structures. The absorptive Ag 2 O shell, together with the coating of a dielectric cover, leads to the cancellation of electric multipole moments in Ag wires, thereby drastically suppressing plasmon-mediated scattering over the full visible spectrum and rendering Ag wires to be invisible. Simultaneously with the effect of invisibility, the transmittance of Ag/Ag 2 O wires is significantly improved compared to bare Ag wires, despite the formation of an absorptive Ag 2 O shell. As an application example, we demonstrate that these invisible Ag wires serve as a high-clarity, high-transmittance, and high-speed defroster for automotive windshields.

Generation of fast protons by interaction of modest laser intensities with H2O “snow” nano-wire targets

NASA Astrophysics Data System (ADS)

Bruner, Nir; Schleifer, Elad; Palchan, Tala; Pikuz, Sergey A.; Eisenmann, Shmuel; Botton, Mordechai; Gordon, Dan; Zigler, Arie

2011-10-01

We report on the generation of protons with energies of 5.5 MeV when irradiating an H 2O nano-wire layer grown on a sapphire plate with an intensity of 5×10 17 W/cm 2. A theoretical model is suggested in which plasma near the tip of the wire is subject to enhanced electrical fields and protons are accelerated to several MeVs.

A study on electromigration-inducing intergranular fracture of fine silver alloy wires

NASA Astrophysics Data System (ADS)

Hsueh, Hao-Wen; Hung, Fei-Yi; Lui, Truan-Sheng

2017-01-01

In this study, Pd-coated Cu, Ag (purity = 4 N), and Ag alloy (Ag-8Au-3Pd) wires were employed to measure the tensile properties during current stressing using the so-called dynamic current tensile (DCT) test. Both the tensile strength and elongation of the wires decreased dramatically in the DCT test, particularly of the Ag-based wires, and the fracture morphology of the Cu-based and Ag-based wires was ductile fracture and intergranular fracture, respectively. Compared to the Cu-based wires, electromigration occurred more easily in the Ag-based wires, and it always generated voids and cracks at the grain boundaries; therefore, the fracture morphology of the Ag-based wires was intergranular fracture owing to the weakened grain boundary. Further, the results indicated that the Ag-based wires could not carry a higher current density than the Cu-based wires, primarily because their extremely low strength and elongation in current stressing might cause serious reliability problems.

Efficiency enhancement of flexible OLEDs by using nano-corrugated substrates and conformal Ag transparent anodes

NASA Astrophysics Data System (ADS)

Wang, Li; Luo, Yu; Feng, Xueming; Pei, Yuechen; Lu, Bingheng; Cheng, Shenggui

2018-05-01

In flexible OLEDs (FOLEDs), the traditional ITO anode has disadvantages such as refractive-index mismatches among substrate and other functional layers, leads to light loss of nearly 80%, meanwhile, its brittle nature and lack in raw materials hinder its further applications. We investigated an efficient FOLED using a semi-transparent silver (Ag) anode, whereas the device was built on a nano-corrugated flexible polycarbonate (PC) substrate prepared by thermal nanoimprint lithography. The corrugations were well preserved on each layer of the device, both the micro-cavity effect and surface plasmon polariton (SPP) modes of light loss were effectively suppressed. As a result, the current efficiency of the FOLED using a conformal corrugated Ag anode enhanced by 100% compared with a planar Ag anode device, and enhanced by 13% with conventional ITO device. In addition, owing to the quasi-periodical arrangements of the corrugations, the device achieved broad spectra and Lambertian angular emission. The Ag anode significantly improved the bending properties of the OLED as compared to the conventional ITO device, leading to a longer lifetime in practical use. The proposed manufacturing strategy will be useful for fabricating nano corrugations on plastic substrate of FOLED in a cost-effective and convenient manner.

Proton acceleration to above 5.5 MeV by interaction of 1017 W/cm2 laser pulse with H2O nano-wire targets

NASA Astrophysics Data System (ADS)

Schleifer, E.; Bruner, N.; Eisenmann, S.; Botton, M.; Pikuz, S. A., Jr.; Faenov, A. Y.; Gordon, D.; Zigler, A.

2011-05-01

Compact sources of high energy protons (50-500MeV) are expected to be key technology in a wide range of scientific applications 1-8. Particularly promising is the target normal sheah acceleration (TNSA) scheme 9,10, holding record level of 67MeV protons generated by a peta-Watt laser 11. In general, laser intensity exceeding 1018 W/cm2 is required to produce MeV level protons. Enhancing the energy of generated protons using compact laser sources is very attractive task nowadays. Recently, nano-scale targets were used to accelerate ions 12,13. Here we report on the first generation of 5.5-7.5MeV protons by modest laser intensities (4.5 × 1017 W/cm2) interacting with H2O nano-wires (snow) deposited on a Sapphire substrate. In this setup, the plasma near the tip of the nano-wire is subject to locally enhanced laser intensity with high spatial gradients, and confined charge separation is obtained. Electrostatic fields of extremely high intensities are produced, and protons are accelerated to MeV-level energies. Nano-wire engineered targets will relax the demand of peak energy from laser based sources.

Detection of alprazolam with a lab on paper economical device integrated with urchin like Ag@ Pd shell nano-hybrids.

PubMed

Narang, Jagriti; Malhotra, Nitesh; Singhal, Chaitali; Mathur, Ashish; Pn, Anoop Krishna; Pundir, C S

2017-11-01

We present results of the studies relating to fabrication of a microfluidic biosensor chip based on urchin like Ag@ Pd shell nano-hybrids that is capable of sensing alprazolam through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of alprazolam present in buffer solutions at clinically relevant concentrations. Methylene blue (MB) was also doped as redox transition substance for sensing alprazolam. Nano-hybrids modified EμPAD showed wide linear range 1-300ng/ml and low detection limit of 0.025ng/l. Low detection limit can further enhance its suitability for forensic application. Nano-hybrids modified EμPAD was also employed for determination of drug in real samples such as human urine. Reported facile lab paper approach integrated with urchin like Ag@ Pd shell nano-hybrids could be well applied for the determination of serum metabolites. Copyright © 2016 Elsevier B.V. All rights reserved.

Structural-Phase States of Fe-Cu and Fe-Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

NASA Astrophysics Data System (ADS)

Lerner, M. I.; Bakina, O. V.; Pervikov, A. V.; Glazkova, E. A.; Lozhkomoev, A. S.; Vorozhtsov, A. B.

2018-05-01

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe-Cu and Fe-Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

Structural-Phase States of Fe–Cu and Fe–Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

NASA Astrophysics Data System (ADS)

Lerner, M. I.; Bakina, O. V.; Pervikov, A. V.; Glazkova, E. A.; Lozhkomoev, A. S.; Vorozhtsov, A. B.

2018-05-01

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe-Cu and Fe-Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

Speciation and Lability of Ag-, AgCl- and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films

EPA Science Inventory

Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-) and silver sulfide nanoparticles (Ag₂S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-D...

Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

NASA Astrophysics Data System (ADS)

Rajendran, V.; Deepa, B.

2018-03-01

Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

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

Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele

2012-10-29

Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

Red light emitting nano-PVP fibers that hybrid with Ag@SiO2@Eu(tta)3phen-NPs by electrostatic spinning method

NASA Astrophysics Data System (ADS)

Zhang, Xiaolin; Tang, Jianguo; Li, Haidong; Wang, Yao; Wang, Xinzhi; Wang, Yanxin; Huang, Linjun; Belfiore, Laurence A.

2018-04-01

This work demonstrated red light emitting nano-PVP fibers that incorporated with novel three-layer nanostructure of Ag@SiO2@Eu(tta)3phen nanoparticles (Ag@SiO2@Eu(tta)3phen-NPs), and the hybrid nano-PVP fibers were fabricated via a remarkably simple electrostatic spinning method. For Ag@SiO2@Eu(tta)3phen-NPs, the thickness of SiO2 is optimized to obtain the maximum luminescent intensity, as results, the optimized thickness of SiO2 is 20 nm. And the corresponding luminescent intensity (612 nm) of the Ag@SiO2@Eu(tta)3phen-NPs is enhanced up to 10 times compared with the pure Eu(tta)3phen complex, which indicates that with 20 nm SiO2 thickness, the localized surface plasmon resonance (LSPR) effect of Ag@SiO2 exhibits highest performance for enhancing luminescence. Moreover, the luminescent PVP fibers emit bright red light under the fluorescence microscope, which definitely confirms that the microenvironment provided by PVP polymer is absolutely suitable for the fluorescent composites.

Construction of AgBr nano-cakes decorated Ti3+ self-doped TiO2 nanorods/nanosheets photoelectrode and its enhanced visible light driven photocatalytic and photoelectrochemical properties

NASA Astrophysics Data System (ADS)

Deng, Xiaoyong; Zhang, Huixuan; Guo, Ruonan; Cheng, Xiuwen; Cheng, Qingfeng

2018-05-01

In the study, AgBr nano-cakes decorated Ti3+ self-doped TiO2 nanorods/nanosheets (AgBr-Ti3+/TiO2 NRs/NSs) photoelectrode with enhanced visible light driven photocatalytic (PC) and photoelectrochemical (PECH) performance has been successfully fabricated by hydrothermal reaction, followed by sodium borohydride reduction and then successive ionic layer adsorption and reaction (SILAR) treatment. Afterwards, series of characterizations were conducted to study the physicochemical properties of AgBr-Ti3+/TiO2 NRs/NSs photoelectrode. Results indicated that AgBr nano-cakes with sizes varying from 110 to 180 nm were uniformly decorated on the surface of Ti3+/TiO2 NRs/NSs to form AgBr-Ti3+/TiO2 NRs/NSs photoelectrode. Moreover, PC activity of AgBr-Ti3+/TiO2 NRs/NSs photoelectrode was measured by degradation of methylene blue (MB). It was found that AgBr-Ti3+/TiO2 NRs/NSs photoelectrode exhibited higher PC activity (98.7%) than that of other samples within 150 min visible light illumination, owing to the enhancement of visible light harvesting and effective separation of photoproduced charges. Thus, AgBr nano-cakes and Ti3+ exerted a huge influence on the PC and PECH properties of AgBr-Ti3+/TiO2 NRs/NSs photoelectrode. Furthermore, the possible enhanced visible light driven PC mechanism of AgBr-Ti3+/TiO2 NRs/NSs was proposed and confirmed.

Aligned hierarchical Ag/ZnO nano-heterostructure arrays via electrohydrodynamic nanowire template for enhanced gas-sensing properties.

PubMed

Yin, Zhouping; Wang, Xiaomei; Sun, Fazhe; Tong, Xiaohu; Zhu, Chen; Lv, Qiying; Ye, Dong; Wang, Shuai; Luo, Wei; Huang, YongAn

2017-09-22

Gas sensing performance can be improved significantly by the increase in both the effective gas exposure area and the surface reactivitiy of ZnO nanorods. Here, we propose aligned hierarchical Ag/ZnO nano-heterostructure arrays (h-Ag/ZnO-NAs) via electrohydrodynamic nanowire template, together with a subsequent hydrothermal synthesis and photoreduction reaction. The h-Ag/ZnO-NAs scatter at top for higher specific surface areas with the air, simultaneously contact at root for the electrical conduction. Besides, the ZnO nanorods are uniformly coated with dispersed Ag nanoparticles, resulting in a tremendous enhancement of the surface reactivity. Compared with pure ZnO, such h-Ag/ZnO-NAs exhibit lower electrical resistance and faster responses. Moreover, they demonstrate enhanced NO 2 gas sensing properties. Self-assembly via electrohydrodynamic nanowire template paves a new way for the preparation of high performance gas sensors.

Formation and properties of hyaluronan/nano Ag and hyaluronan-lecithin/nano Ag films.

PubMed

Khachatryan, Gohar; Khachatryan, Karen; Grzyb, Jacek; Fiedorowicz, Maciej

2016-10-20

A facile and environmentally friendly method of the preparation of silver nanoparticles embedded in hyaluronan (Hyal/Ag) and hyaluronan-lecithin (Hyal-L/Ag) matrix was developed. Thin, elastic foils were prepared from gels by an in situ synthesis of Ag in an aqueous solution of sodium hyaluronate (Hyal), using aq. d-(+)-xylose solution as a reducing agent. The gels were applied to a clean, smooth, defatted Teflon surface and left for drying in the air. The dry foils were stored in a closed container. UV-vis spectroscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectra confirmed formation of about 10nm ball-shaped Ag nanoparticles situated within the polysaccharide template. Thermal properties of the composites were characterized involving differential scanning calorimetry (DSC) and thermogravimetric (TGA) analyses, whereas molecular weights of polysaccharide chains of the matrix were estimated with the size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). An increase in the molecular weight of the hyaluronate after generation of Ag nanoparticles was observed. The foils showed specific properties. The study confirmed that silver nanoparticles can be successfully prepared with environmentally friendly method, using hyaluronan as a stabilizing template. Hyaluronan and hyaluronan-lecithin matrices provide nanocrystals uniform in size and shape. The composites demonstrated a bacteriostatic activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quench degradation limit of multifilamentary AgBi 2Sr 2CaCu 2O x round wires

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

Ye, Liyang; Li, Pei; Shen, Tengming

Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi 2Sr 2CaCu 2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index ofmore » the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A/mm 2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.« less

Quench degradation limit of multifilamentary AgBi 2Sr 2CaCu 2O x round wires

DOE PAGES

Ye, Liyang; Li, Pei; Shen, Tengming; ...

2016-02-02

Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi 2Sr 2CaCu 2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index ofmore » the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A/mm 2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.« less

Thermodynamic and structural properties of hcp bulk and nano-precipitated Ag-Al.

NASA Astrophysics Data System (ADS)

Zarkevich, Nikolai; Johnson, Duane; Smirnov, Andrei

2002-03-01

We study the short- and long- range chemical ordering in hcp bulk Ag_2Al using the Monte Carlo method based on a Hamiltonian constructed via structural formation energies from ab initio electronic-structure calculations. We find that the ground-state structure and thermodynamic properties of bulk Ag_2Al is that determined from the X-ray experimental data. We also address the influence of the interface, coherency strain, and off-stoichiometric disorder on the structure of metastable γ' nano-precipitates in fcc Al matrix. We show that γ' precipitates are off-stoichiometric and provide a new Al-rich structure that reproduces the observed TEM image. We acknowledge our support in part by an ALCOA Foundation Grant, the U.S. Department of Energy through the Frederick Seitz Materials Research Laboratory at UIUC under grant DEFG02-91ER45439, and the UIUC Materials Computation Center under National Science Foundation grant DMR-9976550.

A 3D graphene interface (Si-doped) of Ag matrix with excellent electronic transmission and thermal conductivity via nano-assembly modification

NASA Astrophysics Data System (ADS)

Ye, Xianzhu; Li, Ming; Zhang, Yafei

2018-04-01

The wide development of electronic materials requires higher load capacity and high temperature resistance. In this study, a novel architecture was fabricated consisting of a 3D reduced graphene oxide (rGO)-Si interface using a simple nano-assembly sintering to achieve high current capacity and excellent thermal features. Via the analysis of catalytic oxidation for methanol, the loading catalytic activity of nano-Ag still remained to a certain extent for the composite with 0.8 vol.% rGO. The final Ag-rGO composite apparently possesses a higher initial oxidation temperature and lower rate of oxidation for internal passing and shielding, and the thermal conductivity is significantly enhanced from 344 to 407 W m‑1 K‑1. Importantly, with a 3D synergistic transportation network, the resistivity of the Ag-rGO composite is much lower than pure Ag, and with a longer conductive time under a stress condition of current density of 6.0  ×  104 A cm‑2. Thermal-electronic features demonstrate that the dispersed graphene interface can efficiently suppress the primary failure pathways (high temperature) in Ag matrix and make it uniquely efficient for the advancement of microscale and thermal-management electronics.

Preparation of silver nano-particles immobilized onto chitin nano-crystals and their application to cellulose paper for imparting antimicrobial activity.

PubMed

Li, Zhihan; Zhang, Ming; Cheng, Dong; Yang, Rendang

2016-10-20

Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5-12nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nano-volcanic Eruption of Silver

NASA Astrophysics Data System (ADS)

Lin, Shih-Kang; Nagao, Shijo; Yokoi, Emi; Oh, Chulmin; Zhang, Hao; Liu, Yu-Chen; Lin, Shih-Guei; Suganuma, Katsuaki

2016-10-01

Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. Ag thin films are extensively used in modern electronics primarily because of their oxidation-resistance. Here we report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). It involves grain boundary liquation, the ejection of transient Ag-O fluids through grain boundaries, and the decomposition of Ag-O fluids into O2 gas and suspended Ag and Ag2O clusters. Subsequent coating with re-deposited Ag-O and the de-alloying of O yield a conformal amorphous Ag coating. Patterned Ag hillock arrays and direct Ag-to-Ag bonding can be formed by the homogenous crystallization of amorphous coatings. The Ag “nano-volcanic eruption” mechanism is elaborated, shedding light on a new mechanism of hillock formation and new applications of amorphous Ag coatings.

Nano-volcanic Eruption of Silver.

PubMed

Lin, Shih-Kang; Nagao, Shijo; Yokoi, Emi; Oh, Chulmin; Zhang, Hao; Liu, Yu-Chen; Lin, Shih-Guei; Suganuma, Katsuaki

2016-10-05

Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. Ag thin films are extensively used in modern electronics primarily because of their oxidation-resistance. Here we report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). It involves grain boundary liquation, the ejection of transient Ag-O fluids through grain boundaries, and the decomposition of Ag-O fluids into O 2 gas and suspended Ag and Ag 2 O clusters. Subsequent coating with re-deposited Ag-O and the de-alloying of O yield a conformal amorphous Ag coating. Patterned Ag hillock arrays and direct Ag-to-Ag bonding can be formed by the homogenous crystallization of amorphous coatings. The Ag "nano-volcanic eruption" mechanism is elaborated, shedding light on a new mechanism of hillock formation and new applications of amorphous Ag coatings.

Synthesis and properties of Ag/ZnO/g-C3N4 ternary micro/nano composites by microwave-assisted method

NASA Astrophysics Data System (ADS)

Zhang, Zijie; Li, Xuexue; Chen, Haitao; Shao, Gang; Zhang, Rui; Lu, Hongxia

2018-01-01

Ag/ZnO/g-C3N4 ternary micro/nanocomposites, as novel visible-light-driven photocatalysts, were prepared by a simple and convenient microwave-assisted method. The resulting ternary structure micro/nano composites were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy and infrared radiation techniques to examine its phase structure, valence state, morphological, thermal and optical properties. Well crystallized Ag/ZnO/g-C3N4 ternary micro/nano composites were synthesized under microwave-radiation for 15 min with the output of 240 W. Further experiments indicated Ag(5.0mol%)/ZnO/g-C3N4 photocatalyst in degradation of methylene blue exhibited an outstanding photocatalytic activity and its reaction rate constant (k, 0.0084 min-1) is 7.5, 2.4 2.9 and 3.5 times higher than that of monolithic ZnO (k, 0.0011 min-1), ZnO/g-C3N4(k, 0.0035 min-1), Ag(5 mol%)/ZnO(k, 0.0029 min-1) and Ag(5mol%)/g-C3N4 (k, 0.0024 min-1) respectively. Finally, a possible photocatalytic mechanism of Ag/ZnO/g-C3N4 photocatalyst in degradation process was proposed. This work provides a feasible strategy to synthesize an efficient ZnO-based photocatalyst which combines structure and properties of different dimensional components and made this ternary system an exciting candidate for sunlight-driven photocatalytic water treatment.

Development of a persistent superconducting joint between Bi-2212/Ag-alloy multifilamentary round wires

NASA Astrophysics Data System (ADS)

Chen, Peng; Trociewitz, Ulf P.; Davis, Daniel S.; Bosque, Ernesto S.; Hilton, David K.; Kim, Youngjae; Abraimov, Dmytro V.; Starch, William L.; Jiang, Jianyi; Hellstrom, Eric E.; Larbalestier, David C.

2017-02-01

Superconducting joints are one of the key components needed to make Ag-alloy clad Bi2Sr2CaCu2O8+x (Bi-2212) superconducting round wire (RW) successful for high-field, high-homogeneity magnet applications, especially for nuclear magnetic resonance magnets in which persistent current mode operation is highly desired. In this study, a procedure for fabricating superconducting joints between Bi-2212 RWs during coil reaction was developed. Melting temperatures of Bi-2212 powder with different amounts of Ag addition were investigated by differential thermal analysis so as to provide information for selecting the proper joint matrix. Test joints of 1.3 mm dia. wires heat treated in 1 bar flowing oxygen using the typical partial melt Bi-2212 heat treatment (HT) had transport critical currents I c of ˜900 A at 4.2 K and self-field, decreasing to ˜480 A at 14 T evaluated at 0.1 μV cm-1 at 4.2 K. Compared to the I c of the open-ended short conductor samples with identical 1 bar HT, the I c values of the superconducting joint are ˜20% smaller than that of conductor samples measured in parallel field but ˜20% larger than conductor samples measured in perpendicular field. Microstructures examined by scanning electron microscopy clearly showed the formation of a superconducting Bi-2212 interface between the two Bi-2212 RWs. Furthermore, a Bi-2212 RW closed-loop solenoid with a superconducting joint heat treated in 1 bar flowing oxygen showed an estimated joint resistance below 5 × 10-12 Ω based on its field decay rate. This value is sufficiently low to demonstrate the potential for persistent operation of large inductance Bi-2212 coils.

Morphology-controlled synthesis of Ag{sub 3}PO{sub 4} nano/microcrystals and their antibacterial properties

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

Wu, Aiping; Tian, Chungui, E-mail: tianchungui@yahoo.com.cn; Chang, Wei

Graphical abstract: The Ag{sub 3}PO{sub 4} with rhombic dodecahedral, spherical and small size particles were controllable fabricated just by changing the types of the solvent. The materials possess good antibacterial properties toward different kinds of bacteria. - Highlights: • The Ag{sub 3}PO{sub 4} with three morphologies were controllable fabricated. • The Ag{sub 3}PO{sub 4} as-prepared possess obvious antibacterial properties in the dark. • The antibacterial ability of Ag{sub 3}PO{sub 4} could be greatly improved under the visible light irradiation. - Abstract: We reported the controllable fabrication of Ag{sub 3}PO{sub 4} nano/microcrystals through a simple solution-based precipitation reaction. The samples weremore » characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and infrared spectroscopy. The results indicated that the Ag{sub 3}PO{sub 4} crystals with three different morphology, including the rhombic dodecahedron of 500 nm, the sphere of 100 nm and the particles with small-size of 20 nm, could be obtained in the solvents of water, ethylene glycol (EG) and dimethyl sulfoxide (DMSO). The antibacterial assay showed that all samples possess obvious antibacterial properties. In addition, the Ag{sub 3}PO{sub 4} with small size of 20 nm showed better activity due to their high specific surface areas. Notably, we have found that the antibacterial ability of Ag{sub 3}PO{sub 4} could be greatly improved under the visible light irradiation, which are superior to that in the dark and commercial streptomycin.« less

Nano-sculptured Janus-like TiAg thin films obliquely deposited by GLAD co-sputtering for temperature sensing.

PubMed

Pedrosa, Paulo; Ferreira, Armando; Martin, Nicolas; Arab Pour Yazdi, Mohammad; Billard, Alain; Lanceros-Mendez, Senentxu; Vaz, Filipe

2018-06-11

Inclined, zigzag and spiral TiAg films were prepared by GLancing Angle Deposition (GLAD), using two distinct Ti and Ag targets with a particle incident angle of 80º and Ag contents ranging from 20 to 75 at. %. The effect of increasing Ag incorporation and columnar architecture change on the morphological, structural and electrical properties of the films was investigated. It is shown that inclined columnar features (β = 47º) with high porosity were obtained for 20 at. % Ag, with the column angle sharply decreasing (β = 21º) for 50 at. % Ag, and steeply increasing afterwards until 37º for the film with 75 at. % Ag. The sputtered films exhibit a rather well-crystallized structure for Ag contents ≥ 50 at. %, with a TiAg (111) preferential growth. No significant oxidation was detected in all films, except for the one with 20 at. % Ag, after two 298-473-298 K temperature cycles in air. The calculated temperature coefficient of resistivity (TCR) values vary between 1.4 and 5.5×10-4 K-1. Nano-sculptured spiral films exhibit consistently higher resistivity (ρ = 1.5×10-6 Ω m) and TCR values (2.9×10-4 K-1) than the inclined one with the same Ag content (ρ = 1.2×10-6 Ω m and TCR = 2.0×10-4 K-1). No significant changes are observed in the zigzag films concerning these properties. The effective anisotropy Aeff at 473 K changes from 1.3 to 1.7 for the inclined films. Spiral films exhibit an almost completely isotropic behavior with Aeff = 1.1. Ag-rich TiAg core + shell Janus-like columns were obtained with increasing Ag concentrations. © 2018 IOP Publishing Ltd.

Effect of addition of Ag nano powder on mechanical properties of epoxy/polyaminoamide adduct coatings filled with conducting polymer

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

Samad, Ubair Abdus; Center of excellence for research in engineering materials; Khan, Rawaiz

In this study the effect of Ag Nano powder on mechanical properties of epoxy coatings filled with optimized ratio of conducting polymers (Polyaniline and Polyppyrole) was evaluated. Bisphenol A diglycidyl ether epoxy resin (DGEBA) along with polyaminoamide adduct (ARADUR 3282-1 BD) is used as curing agent under optimized stoichiometry values. Curing is performed at room temperature with different percentages of Nano filler. Glass and steel panels were used as coating substrate. Bird applicator was used to coat the samples in order to obtain thin film with wet film thickness (WFT) of about 70-90 µm. The samples were kept in dust freemore » environment for about 7 days at room temperature for complete curing. The coated steel panels were used to evaluate the mechanical properties of coating such as hardness, scratch and impact tests whereas coated glass panels were used for measuring pendulum hardness of the coatings. To check the dispersion and morphology of Nano filler in epoxy matrix scanning electron microscopy (SEM) was used in addition Nano indentation was also performed to observe the effect of Nano filler on modulus of elasticity and hardness at Nano scale.« less

Effect of addition of Ag nano powder on mechanical properties of epoxy/polyaminoamide adduct coatings filled with conducting polymer

NASA Astrophysics Data System (ADS)

Samad, Ubair Abdus; Khan, Rawaiz; Alam, Mohammad Asif; Al-Othman, Othman Y.; Al-Zahrani, Saeed M.

2015-05-01

In this study the effect of Ag Nano powder on mechanical properties of epoxy coatings filled with optimized ratio of conducting polymers (Polyaniline and Polyppyrole) was evaluated. Bisphenol A diglycidyl ether epoxy resin (DGEBA) along with polyaminoamide adduct (ARADUR 3282-1 BD) is used as curing agent under optimized stoichiometry values. Curing is performed at room temperature with different percentages of Nano filler. Glass and steel panels were used as coating substrate. Bird applicator was used to coat the samples in order to obtain thin film with wet film thickness (WFT) of about 70-90 µm. The samples were kept in dust free environment for about 7 days at room temperature for complete curing. The coated steel panels were used to evaluate the mechanical properties of coating such as hardness, scratch and impact tests whereas coated glass panels were used for measuring pendulum hardness of the coatings. To check the dispersion and morphology of Nano filler in epoxy matrix scanning electron microscopy (SEM) was used in addition Nano indentation was also performed to observe the effect of Nano filler on modulus of elasticity and hardness at Nano scale.

Effect of Ozone Treatment on Nano-Sized Silver Sulfide in Wastewater Effluent.

PubMed

Thalmann, Basilius; Voegelin, Andreas; von Gunten, Urs; Behra, Renata; Morgenroth, Eberhard; Kaegi, Ralf

2015-09-15

Silver nanoparticles used in consumer products are likely to be released into municipal wastewater. Transformation reactions, most importantly sulfidation, lead to the formation of nanoscale silver sulfide (nano-Ag2S) particles. In wastewater treatment plants (WWTP), ozonation can enhance the effluent quality by eliminating organic micropollutants. The effect of ozonation on the fate of nano-Ag2S, however, is currently unknown. In this study, we investigate the interaction of ozone with nano-Ag2S and evaluate the effect of ozonation on the short-term toxicity of WWTP effluent spiked with nano-Ag2S. The oxidation of nano-Ag2S by ozone resulted in a stoichiometric factor (number of moles of ozone required to oxidize one mole of sulfide to sulfate) of 2.91, which is comparable to the results obtained for the reaction of bisulfide (HS(-)) with ozone. The second-order rate constant for the reaction of nano-Ag2S with ozone (k = 3.1 × 10(4) M(-1) s(-1)) is comparable to the rate constant of fast-reacting micropollutants. Analysis of the ozonation products of nano-Ag2S by transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS) revealed that ozonation dominantly led to the formation of silver chloride in WWTP effluent. After ozonation of the Ag2S-spiked effluent, the short-term toxicity for the green algae Chlamydomonas reinhardtii increased and reached EC50 values comparable to Ag(+). This study thus reveals that ozone treatment of WWTP effluent results in the oxidation of Ag2S and, hence, an increase of the Ag toxicity in the effluent, which may become relevant at elevated Ag concentrations.

Thermoelectric Mechanism and Interface Characteristics of Cyanide-Free Nanogold-Coated Silver Wire

NASA Astrophysics Data System (ADS)

Tseng, Yi-Wei; Hung, Fei-Yi; Lui, Truan-Sheng

2016-01-01

Traditional bath-plated gold contains a cyanide complex, which is an environmental hazard. In response, our study used a green plating process to produce cyanide-free gold-coated silver (cyanide-free ACA) bonding wire that has been proven to be a feasible alternative to gold bonding wire in semiconductor packaging. In this work, ACA wire annealed at 550°C was found to have stable microstructure and superior mechanical properties. Intermetallic compounds Ag2Al and AuAl2 grew from Ag-Au balls and Al pads after aging at 175°C for 500 h. After current testing, ACA wire was found to have improved electrical properties due to equiaxed grain growth. The gold nanolayer on the Ag surface increased the oxidation resistance. These results provide insights regarding the reliability of ACA wire in advanced bonding processes.

Influences of the Bi2Sr2CaCu2Ox/Ag interface and interfilamentary bridge connections on AC loss of composite wires

NASA Astrophysics Data System (ADS)

Jiang, Zhao-Fei; Xue, Feng; Gou, Xiao-Fan

2018-04-01

The microstructure of Bi2Sr2CaCu2Ox (Bi2212) filamentary composite round wires (RWs) changes to be extremely complicated after heat treatment, with the interface between Bi2212 filaments and Ag matrix being meandering and a lot of bridge connections (BCs) generating between filaments. The influence of such the unique microstructure on the electromagnetic behavior and especially the AC loss has not been far from completely understanding. In this paper, according to the H formulation and on the nonlinear E-J relationship, we developed a finite element model, and further on this model evaluated the current and AC loss of a Bi2212 multifilamentary wire with the rough Bi2212/Ag interface and several BCs between filaments under the alternating magnetic field (Hex(t) = H0sin2πft). Through the comparative study, we found that the penetration magnetic field Hp is a critical turning point and on this base the influences of such the complex microstructure are quite different when the amplitude of applied magnetic field H0 < Hp and when H0 > Hp. The rough interface impacts the current distribution and causes the local heat concentrated at the concave locations. For BCs between Bi2212 filaments, it is most significant that they can share the current and make the current redistribute between filaments. Further for the wire with various types of BCs, the current distribution and the AC loss relative to the wire without BCs (Q / QmagnoBCs) were comprehensively investigated.

Embrittlement phenomenon of Ag core MP35N cable as lead conductor in medical device.

PubMed

Wang, Ling; Li, Bernie; Zhang, Haitao

2013-02-01

Ag core MP35N (Ag/MP35N) wire has been used in lead electric conductor wires in the medical device industry for many years. Recently it was noticed that the combination of silver and MP35N restricts its wire drawing process. The annealing temperature in Ag/MP35N has to be lower than the melting temperature of pure Ag (960 °C), which cannot fully anneal MP35N. The lower annealing temperature results in a highly cold worked MP35N, which significantly reduces Ag/MP35N ductility. The embrittlement phenomenon of Ag/MP35N cable was observed in tension and bending deformation. The effect of the embrittlement on the wire flex fatigue life was evaluated using a newly developed flex fatigue testing method. The Ag/MP35N cable fatigue results was analyzed with a Coffin-Manson approach and compared to the MP35N cable fatigue results. The root causes of the Ag/Mp35N embrittlement phenomenon are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Evaluation of a Ag/Ag 2S reference electrode with long-term stability for electrochemistry in ionic liquids

DOE PAGES

Horwood, Corie; Stadermann, Michael

2018-02-08

We report on a reference electrode designed for use in ionic liquids, based on a silver wire coated with silver sulfide. The reference electrode potential is determined by the concentrations of Ag + and S 2-, which are established by the solubility of the Ag 2S coating on the Ag wire. While potential shifts of >100 mV during an experiment have been reported when using silver or platinum wire quasi-reference electrodes, the reference electrode reported here provides a stable potential over several months of experimental use. Additionally, our reference electrode can be prepared and used in a normal air atmosphere,more » and does not need to be assembled and used in a glovebox, or protected from light. In conclusion, the reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five of the six ionic liquids investigated.« less

Evaluation of a Ag/Ag 2S reference electrode with long-term stability for electrochemistry in ionic liquids

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

Horwood, Corie; Stadermann, Michael

We report on a reference electrode designed for use in ionic liquids, based on a silver wire coated with silver sulfide. The reference electrode potential is determined by the concentrations of Ag + and S 2-, which are established by the solubility of the Ag 2S coating on the Ag wire. While potential shifts of >100 mV during an experiment have been reported when using silver or platinum wire quasi-reference electrodes, the reference electrode reported here provides a stable potential over several months of experimental use. Additionally, our reference electrode can be prepared and used in a normal air atmosphere,more » and does not need to be assembled and used in a glovebox, or protected from light. In conclusion, the reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five of the six ionic liquids investigated.« less

Enhancement in biological response of Ag-nano composite polymer membranes using plasma treatment for fabrication of efficient bio materials

NASA Astrophysics Data System (ADS)

Agrawal, Narendra Kumar; Sharma, Tamanna Kumari; Chauhan, Manish; Agarwal, Ravi; Vijay, Y. K.; Swami, K. C.

2016-05-01

Biomaterials are nonviable material used in medical devices, intended to interact with biological systems, which are becoming necessary for the development of artificial material for biological systems such as artificial skin diaphragm, valves for heart and kidney, lenses for eye etc. Polymers having novel properties like antibacterial, antimicrobial, high adhesion, blood compatibility and wettability are most suitable for synthesis of biomaterial, but all of these properties does not exist in any natural or artificial polymeric material. Nano particles and plasma treatment can offer these properties to the polymers. Hence a new nano-biomaterial has been developed by modifying the surface and chemical properties of Ag nanocomposite polymer membranes (NCPM) by Argon ion plasma treatment. These membranes were characterized using different techniques for surface and chemical modifications occurred. Bacterial adhesion and wettability were also tested for these membranes, to show direct use of this new class of nano-biomaterial for biomedical applications.

Omnidirectional color filters capitalizing on a nano-resonator of Ag-TiO2-Ag integrated with a phase compensating dielectric overlay

NASA Astrophysics Data System (ADS)

Park, Chul-Soon; Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2015-02-01

We present a highly efficient omnidirectional color filter that takes advantage of an Ag-TiO2-Ag nano-resonator integrated with a phase-compensating TiO2 overlay. The dielectric overlay substantially improves the angular sensitivity by appropriately compensating for the phase pertaining to the structure and suppresses unwanted optical reflection so as to elevate the transmission efficiency. The filter is thoroughly designed, and it is analyzed in terms of its reflection, optical admittance, and phase shift, thereby highlighting the origin of the omnidirectional resonance leading to angle-invariant characteristics. The polarization dependence of the filter is explored, specifically with respect to the incident angle, by performing experiments as well as by providing the relevant theoretical explanation. We could succeed in demonstrating the omnidirectional resonance for the incident angles ranging to up to 70°, over which the center wavelength is shifted by below 3.5% and the peak transmission efficiency is slightly degraded from 69%. The proposed filters incorporate a simple multi-layered structure and are expected to be utilized as tri-color pixels for applications that include image sensors and display devices. These devices are expected to allow good scalability, not requiring complex lithographic processes.

Tailoring the Hydrothermal Synthesis of Stainless Steel Wire Sieve-Supported Ag-Doped ZnO Nanowires to Optimize Their Photo-catalytic Activity

NASA Astrophysics Data System (ADS)

Jing, W. X.; Shi, J. F.; Xu, Z. P.; Jiang, Z. D.; Wei, Z. Y.; Zhou, F.; Wu, Q.; Cui, Q. B.

2018-03-01

Batches of un-doped and Ag-doped ZnO nanowires (ZnONWs) were prepared hydrothermally on stainless steel wire sieves at varied Zn2+ concentrations of the growth solution and at different Ag+ concentrations of the silver nitrate solution. Methylene blue solution was degraded with these as-prepared ZnONWs in the presences of ultraviolet irradiation. It is found that both the processing parameters greatly affect the surface textures, wettability, and photo-activity of the ZnONWs. The latter synthesizing parameter is optimized only after the former one has been finely regulated. The un-doped and Ag-doped ZnONWs at Zn2+ concentration of 75 mM of the growth solution and at Ag+ concentration of3 mM of the silver nitrate solution both produce Gaussian rough surfaces and in each batch are most hydrophilic. Therefore, in the related batch the contacting surface area of the catalyst is the largest, the hydroxyl radicals attached on the top ends of corresponding ZnONWs the most, and the catalytic activity of these catalysts the optimal. Besides these, the latter synthesizing parameter affects the photo-activity of Ag-doped ZnONWs more significantly than the former one does that of un-doped ZnONWs.

Single Step Laser Transfer and Laser Curing of Ag NanoWires: A Digital Process for the Fabrication of Flexible and Transparent Microelectrodes.

PubMed

Zacharatos, Filimon; Karvounis, Panagiotis; Theodorakos, Ioannis; Hatziapostolou, Antonios; Zergioti, Ioanna

2018-06-19

Ag nanowire (NW) networks have exquisite optical and electrical properties which make them ideal candidate materials for flexible transparent conductive electrodes. Despite the compatibility of Ag NW networks with laser processing, few demonstrations of laser fabricated Ag NW based components currently exist. In this work, we report on a novel single step laser transferring and laser curing process of micrometer sized pixels of Ag NW networks on flexible substrates. This process relies on the selective laser heating of the Ag NWs induced by the laser pulse energy and the subsequent localized melting of the polymeric substrate. We demonstrate that a single laser pulse can induce both transfer and curing of the Ag NW network. The feasibility of the process is confirmed experimentally and validated by Finite Element Analysis simulations, which indicate that selective heating is carried out within a submicron-sized heat affected zone. The resulting structures can be utilized as fully functional flexible transparent electrodes with figures of merit even higher than 100. Low sheet resistance (<50 Ohm/sq) and high visible light transparency (>90%) make the reported process highly desirable for a variety of applications, including selective heating or annealing of nanocomposite materials and laser processing of nanostructured materials on a large variety of optically transparent substrates, such as Polydimethylsiloxane (PDMS).

Demonstration of a Nano-Enabled Space Power System

NASA Technical Reports Server (NTRS)

Raffaelle, Ryne; Hunter, Roger C.; Baker, Christopher

2017-01-01

The Nano-Enabled Space Power System will demonstrate power systems with nanomaterial-enhanced components as are placement for CubeSat power generation, transmission, and storage. Successful flights of these nano-power systems will accelerate the use of this revolutionary technology in the aerospace industry. The use of nano materials in solar cells, wire harnesses,and lithium ion batteries can increase the device performance without significantly altering the devices physical dimensions or the devices operating range (temperature,voltage, current). In many cases, the use of nanomaterials widens the viable range of operating conditions, such as increased depth of discharge of lithium ion batteries, tunable bandgaps in solar cells, and increased flexure tolerance of wire harnesses.

New insights into micro/nanoscale combined probes (nanoAuger, μXPS) to characterize Ag/Au@SiO2 core-shell assemblies

NASA Astrophysics Data System (ADS)

Ledeuil, J. B.; Uhart, A.; Soulé, S.; Allouche, J.; Dupin, J. C.; Martinez, H.

2014-09-01

This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming electron signal (potentially affected by the topography of the material) during analysis. SEM experiments have unambiguously revealed the hollow-morphology of the metal core, while Auger spectroscopy observations showed chemical heterogeneity within the particles (as silver and gold are randomly found in the core ring). To our knowledge, this is the first time that Auger nano probe spectroscopy has been used and successfully optimized for the study of some complex metal/inorganic interfaces at such a high degree of resolution (~12 nm). Complementarily, XPS Au 4f and Ag 3d peaks were finally detected attesting the possibility of access to the whole chemistry of such nanostructured assemblies.This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming

Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

NASA Astrophysics Data System (ADS)

Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

Ballistic induced pumping of hypersonic heat current in DNA nano wire

NASA Astrophysics Data System (ADS)

Behnia, Sohrab; Panahinia, Robabe

2016-12-01

Heat shuttling properties of DNA nano-wire driven by an external force against the spontaneous heat current direction in non-zero temperature bias (non averaged) have been studied. We examined the valid region of driving amplitude and frequency to have pumping state in terms of temperature bias and the system size. It was shown that DNA could act as a high efficiency thermal pump in the hypersonic region. Amplitude-dependent resonance frequencies of DNA indicating intrinsic base pair internal vibrations have been detected. Nonlinearity implies that by increasing the driven amplitude new vibration modes are detected. To verify the results, an analytical parallel investigation based on multifractal concept has been done. By using the geometric properties of the strange attractor of the system, the threshold value to transition to the pumping state for given external amplitude has been identified. It was shown that the system undergoes a phase transition in sliding point to the pumping state. Fractal dimension demonstrates that the ballistic transport is responsible for energy pumping in the system. In the forbidden band gap, DNA could transmit the energy by exceeding the threshold amplitude. Despite of success in energy pumping, in this framework, DNA could not act as a real cooler.

Growth of low temperature silicon nano-structures for electronic and electrical energy generation applications.

PubMed

Gabrielyan, Nare; Saranti, Konstantina; Manjunatha, Krishna Nama; Paul, Shashi

2013-02-15

This paper represents the lowest growth temperature for silicon nano-wires (SiNWs) via a vapour-liquid-solid method, which has ever been reported in the literature. The nano-wires were grown using plasma-enhanced chemical vapour deposition technique at temperatures as low as 150°C using gallium as the catalyst. This study investigates the structure and the size of the grown silicon nano-structure as functions of growth temperature and catalyst layer thickness. Moreover, the choice of the growth temperature determines the thickness of the catalyst layer to be used.The electrical and optical characteristics of the nano-wires were tested by incorporating them in photovoltaic solar cells, two terminal bistable memory devices and Schottky diode. With further optimisation of the growth parameters, SiNWs, grown by our method, have promising future for incorporation into high performance electronic and optical devices.

The structural conversion from α-AgVO3 to β-AgVO3: Ag nanoparticle decorated nanowires with application as cathode materials for Li-ion batteries.

PubMed

McNulty, David; Ramasse, Quentin; O'Dwyer, Colm

2016-09-15

The majority of electrode materials in batteries and related electrochemical energy storage devices are fashioned into slurries via the addition of a conductive additive and a binder. However, aggregation of smaller diameter nanoparticles in current generation electrode compositions can result in non-homogeneous active materials. Inconsistent slurry formulation may lead to inconsistent electrical conductivity throughout the material, local variations in electrochemical response, and the overall cell performance. Here we demonstrate the hydrothermal preparation of Ag nanoparticle (NP) decorated α-AgVO 3 nanowires (NWs) and their conversion to tunnel structured β-AgVO 3 NWs by annealing to form a uniform blend of intercalation materials that are well connected electrically. The synthesis of nanostructures with chemically bound conductive nanoparticles is an elegant means to overcome the intrinsic issues associated with electrode slurry production, as wire-to-wire conductive pathways are formed within the overall electrode active mass of NWs. The conversion from α-AgVO 3 to β-AgVO 3 is explained in detail through a comprehensive structural characterization. Meticulous EELS analysis of β-AgVO 3 NWs offers insight into the true β-AgVO 3 structure and how the annealing process facilitates a higher surface coverage of Ag NPs directly from ionic Ag content within the α-AgVO 3 NWs. Variations in vanadium oxidation state across the surface of the nanowires indicate that the β-AgVO 3 NWs have a core-shell oxidation state structure, and that the vanadium oxidation state under the Ag NP confirms a chemically bound NP from reduction of diffused ionic silver from the α-AgVO 3 NWs core material. Electrochemical comparison of α-AgVO 3 and β-AgVO 3 NWs confirms that β-AgVO 3 offers improved electrochemical performance. An ex situ structural characterization of β-AgVO 3 NWs after the first galvanostatic discharge and charge offers new insight into the Li + reaction

Californium Recovery from Palladium Wire

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

Burns, Jon D.

2014-08-01

The recovery of 252Cf from palladium- 252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO 3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, whichmore » ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.« less

Developing NanoFoil-Heated Thin-Film Thermal Battery

DTIC Science & Technology

2013-09-01

buffer discs (in gray) sandwiching the NanoFoil disc (in yellow). Two Microtherm discs (in dark gray) bracketed the sandwich to prevent excessive heat...of the fuse strip with a Microtherm disc. Cathode Electrolyte Anode Microtherm Heat paper NanoFoil Buffer Agilent 34970A 606.5 Nichrome wire Maccor...gray) sandwiching the NanoFoil disc (in yellow). Two Microtherm discs (in dark gray) bracketed the sandwich to prevent excessive heat loss

Growth of low temperature silicon nano-structures for electronic and electrical energy generation applications

PubMed Central

2013-01-01

This paper represents the lowest growth temperature for silicon nano-wires (SiNWs) via a vapour-liquid–solid method, which has ever been reported in the literature. The nano-wires were grown using plasma-enhanced chemical vapour deposition technique at temperatures as low as 150°C using gallium as the catalyst. This study investigates the structure and the size of the grown silicon nano-structure as functions of growth temperature and catalyst layer thickness. Moreover, the choice of the growth temperature determines the thickness of the catalyst layer to be used. The electrical and optical characteristics of the nano-wires were tested by incorporating them in photovoltaic solar cells, two terminal bistable memory devices and Schottky diode. With further optimisation of the growth parameters, SiNWs, grown by our method, have promising future for incorporation into high performance electronic and optical devices. PMID:23413969

Transport electron through a quantum wire by side-attached asymmetric quantum-dot rings

NASA Astrophysics Data System (ADS)

Rostami, A.; Zabihi, S.; Rasooli S., H.; Seyyedi, S. K.

2011-12-01

The electronic conductance at zero temperature through a quantum wire with side-attached asymmetric quantum ring (as a scatter system) is theoretically studied using the non-interacting Anderson tunneling Hamiltonian method. We show that the asymmetric configuration of QD- scatter system strongly impresses the amplitude and spectrum of quantum wire nanostructure transmission characteristics. It is shown that whenever the balanced number of quantum dots in two rings is substituted by unbalanced scheme, the number of forbidden mini-bands in quantum wire conductance increases and QW-nanostructure electronic conductance contains rich spectral properties due to appearance of the new anti-resonance and resonance points in spectrum. Considering the suitable gap between nano-rings can strengthen the amplitude of new resonant peaks in the QW conductance spectrum. The proposed asymmetric quantum ring scatter system idea in this paper opens a new insight on designing quantum wire nano structure for given electronic conductance.

Effect of silver nano particles on flexural strength of acrylic resins.

PubMed

Sodagar, Ahmad; Kassaee, Mohammad Zaman; Akhavan, Azam; Javadi, Negar; Arab, Sepideh; Kharazifard, Mohammad Javad

2012-04-01

Poly(methyl methacrylate), PMMA, is widely used for fabrication of removable orthodontic appliances. Silver nano particles (AgNps) have been added to PMMA because of their antimicrobial properties. The aim of this study is to investigate the effect of AgNps on the flexural strength of PMMA. Acrylic liquid containing 0.05% and 0.2% AgNps was prepared for two kinds of acrylic resins: Rapid Repair &Selecta Plus. Two groups without AgNps were used as control groups. For each one, flexural strength was investigated via Three Point Bending method for the 15 acrylic blocks. Two-way ANOVA, one way ANOVA and Tukey tests were used for statistical analysis. Rapid Repair without AgNps showed the highest flexural strength. Addition of 0.05% AgNps to Rapid Repair, significantly decreased its flexural strength while, continuing the addition up to 0.2% increased it nearly up to its primary level. In contrast, addition of AgNps to Selecta Plus increased its flexural strength but addition of 0.05% nano particles was more effective than 0.2%. The effect of AgNps on flexural strength of PMMA depends on several factors including the type of acrylics and the concentrations of nano particles. Copyright © 2011 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

New insights into micro/nanoscale combined probes (nanoAuger, μXPS) to characterize Ag/Au@SiO2 core-shell assemblies.

PubMed

Ledeuil, J B; Uhart, A; Soulé, S; Allouche, J; Dupin, J C; Martinez, H

2014-10-07

This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming electron signal (potentially affected by the topography of the material) during analysis. SEM experiments have unambiguously revealed the hollow-morphology of the metal core, while Auger spectroscopy observations showed chemical heterogeneity within the particles (as silver and gold are randomly found in the core ring). To our knowledge, this is the first time that Auger nano probe spectroscopy has been used and successfully optimized for the study of some complex metal/inorganic interfaces at such a high degree of resolution (≈12 nm). Complementarily, XPS Au 4f and Ag 3d peaks were finally detected attesting the possibility of access to the whole chemistry of such nanostructured assemblies.

Ultrathin MoS2 and WS2 layers on silver nano-tips as electron emitters

NASA Astrophysics Data System (ADS)

Loh, Tamie A. J.; Tanemura, Masaki; Chua, Daniel H. C.

2016-09-01

2-dimensional (2D) inorganic analogues of graphene such as MoS2 and WS2 present interesting opportunities for field emission technology due to their high aspect ratio and good electrical conductivity. However, research on 2D MoS2 and WS2 as potential field emitters remains largely undeveloped compared to graphene. Herein, we present an approach to directly fabricate ultrathin MoS2 and WS2 onto Ag nano-tips using pulsed laser deposition at low temperatures of 450-500 °C. In addition to providing a layer of chemical and mechanical protection for the Ag nano-tips, the growth of ultrathin MoS2 and WS2 layers on Ag led to enhanced emission properties over that of pristine nano-tips due to a reduction of the effective barrier height arising from charge injection from Ag to the overlying MoS2 or WS2. For WS2 on Ag nano-tips, the phasic mixture was also an important factor influencing the field emission performance. The presence of 1T-WS2 at the metal-WS2 interface in a hybrid film of 2H/1T-WS2 leads to improvement in the field emission capabilities as compared to pure 2H-WS2 on Ag nano-tips.

Tensile test and interface retention forces between wires and composites in lingual fixed retainers.

PubMed

Paolone, Maria Giacinta; Kaitsas, Roberto; Obach, Patricia; Kaitsas, Vasilios; Benedicenti, Stefano; Sorrenti, Eugenio; Barberi, Fabrizio

2015-06-01

In daily orthodontic clinical practice retention is very important, and lingual retainers are part of this challenge. The failure of lingual retainers may be due to many factors. The aim of this study was to assess the retention forces and mechanical behavior of different types of wires matched with different kinds of composites in lingual retainers. A tensile test was performed on cylindrical composite test specimens bonded to orthodontic wires. The specimens were constructed using four different wires: a straight wire (Remanium .016×.022″ Dentaurum), two round twisted wires (Penta One .0215″ Masel, Gold Penta Twisted .0215″ Gold N'braces) and a rectangular braided wire (D-Rect .016×.022″ Ormco); and three composites: two micro-hybrids (Micro-Hybrid Enamel Plus HFO Micerium, and Micro-Hybrid SDR U Dentsply) and a micro-nano-filled composite (Micro-Nano-Filled Transbond LR 3M). The test was performed at a speed of 10mm/min on an Inström device. The wire was fixed with a clamp. The results showed that the bonding between wires and composites in lingual fixed retainers seemed to be lowest for rectangular smooth wires and increased in round twisted and rectangular twisted wires where the bonding was so strong that the maximum tension/bond strength was greater than the ultimate tensile strength of the wire. The highest values were in rectangular twisted wires. Concerning the composites, hybrid composites had the lowest interface bonding values and broke very quickly, while the nano- and micro-composites tolerated stronger forces and displayed higher bonding values. The best results were observed with the golden twisted wire and reached 21.46 MPa with the Transbond composite. With the rectangular braided wire the retention forces were so high that the Enamel Plus composite fractured when the load exceeded 154.6 N/MPa. When the same wire was combined with the Transbond LR either the wire or the composite broke when the force exceeded 240 N. The results of this

Antibacterial effect of visible light reactive TiO2/Ag nanocomposite thin film on the orthodontic appliances.

PubMed

Yun, Kwidug; Oh, Gyejeong; Vang, Mongsook; Yang, Hongso; Lim, Hyunpil; Koh, Jeongtae; Jeong, Woonjo; Yoon, Dongjoo; Lee, Kyungku; Lee, Kwangmin; Park, Sangwon

2011-08-01

This study evaluated the antibacterial effect of a visible light reactive TiO2/Ag nanocomposite thin film on dental orthodontic wire (STS 304 wire). The growth of S. mutans and A. actinomycetemcomitans was suppressed on the specimens coated with TiO2/Ag compared to the uncoated specimens. The antibacterial effect of the TiO2/Ag nanocomposite thin film was improved under visible light irradiation.

Self-organization of mesoscopic silver wires by electrochemical deposition.

PubMed

Zhong, Sheng; Koch, Thomas; Walheim, Stefan; Rösner, Harald; Nold, Eberhard; Kobler, Aaron; Scherer, Torsten; Wang, Di; Kübel, Christian; Wang, Mu; Hahn, Horst; Schimmel, Thomas

2014-01-01

Long, straight mesoscale silver wires have been fabricated from AgNO3 electrolyte via electrodeposition without the help of templates, additives, and surfactants. Although the wire growth speed is very fast due to growth under non-equilibrium conditions, the wire morphology is regular and uniform in diameter. Structural studies reveal that the wires are single-crystalline, with the [112] direction as the growth direction. A possible growth mechanism is suggested. Auger depth profile measurements show that the wires are stable against oxidation under ambient conditions. This unique system provides a convenient way for the study of self-organization in electrochemical environments as well as for the fabrication of highly-ordered, single-crystalline metal nanowires.

Wire Array Photovoltaics

NASA Astrophysics Data System (ADS)

Turner-Evans, Dan

Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

Depositing High-T(sub c) Superconductors On Normal-Conductor Wires

NASA Technical Reports Server (NTRS)

Kirlin, Peter S.

1994-01-01

Experiments have demonstrated feasibility of depositing thin layers of high-T(sub c) superconductor on normally electrically conductive wires. Superconductivity evident at and below critical temperature (T{sub c}) of 71 K. OMCVD, organometallic vapor deposition, apparatus coats Ag wire with layer high-T(sub c) superconductor. Superconductive phase of this material formed subsequently by annealing under controlled conditions.

InGaAs/InP quantum wires grown on silicon with adjustable emission wavelength at telecom bands

NASA Astrophysics Data System (ADS)

Han, Yu; Li, Qiang; Ng, Kar Wei; Zhu, Si; Lau, Kei May

2018-06-01

We report the growth of vertically stacked InGaAs/InP quantum wires on (001) Si substrates with adjustable room-temperature emission at telecom bands. Based on a self-limiting growth mode in selective area metal–organic chemical vapor deposition, crescent-shaped InGaAs quantum wires with variable dimensions are embedded within InP nano-ridges. With extensive transmission electron microscopy studies, the growth transition and morphology change from quantum wires to ridge quantum wells (QWs) have been revealed. As a result, we are able to decouple the quantum wires from ridge QWs and manipulate their dimensions by scaling the growth time. With minimized lateral dimension and their unique positioning, the InGaAs/InP quantum wires are more immune to dislocations and more efficient in radiative processes, as evidenced by their excellent optical quality at telecom-bands. These promising results thus highlight the potential of combining low-dimensional quantum wire structures with the aspect ratio trapping process for integrating III–V nano-light emitters on mainstream (001) Si substrates.

InGaAs/InP quantum wires grown on silicon with adjustable emission wavelength at telecom bands.

PubMed

Han, Yu; Li, Qiang; Ng, Kar Wei; Zhu, Si; Lau, Kei May

2018-06-01

We report the growth of vertically stacked InGaAs/InP quantum wires on (001) Si substrates with adjustable room-temperature emission at telecom bands. Based on a self-limiting growth mode in selective area metal-organic chemical vapor deposition, crescent-shaped InGaAs quantum wires with variable dimensions are embedded within InP nano-ridges. With extensive transmission electron microscopy studies, the growth transition and morphology change from quantum wires to ridge quantum wells (QWs) have been revealed. As a result, we are able to decouple the quantum wires from ridge QWs and manipulate their dimensions by scaling the growth time. With minimized lateral dimension and their unique positioning, the InGaAs/InP quantum wires are more immune to dislocations and more efficient in radiative processes, as evidenced by their excellent optical quality at telecom-bands. These promising results thus highlight the potential of combining low-dimensional quantum wire structures with the aspect ratio trapping process for integrating III-V nano-light emitters on mainstream (001) Si substrates.

A nano lamella NbTi–NiTi composite with high strength

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

Jiang, Jiang; Jiang, Daqiang; Hao, Shijie

A hypereutectic Nb60Ti24Ni16 (at%) alloy was prepared by vacuum induction melting, and a nano lamellae NbTi-NiTi composite was obtained by hot-forging and wire-drawing of the ingot Microscopic analysis showed that NbTi and NiTi nano lamellae distributed alternatively in the composite, and aligned along the wire axial direction, with a high volume fraction (similar to 70%) of NbTi nano lamellae. In situ synchrotron X-ray diffraction analysis revealed that stress induced martensitic transformation occurred upon loading, which would effectively weaken the stress concentration at the interface and avoid the introduction of defects into the nano reinforced phase. Then the embedded NbTi nanomore » lamellae exhibited a high elastic strain up to 2.72%, 1.5 times as high as that of the Nb nanowires embedded in a conventional plastic matrix, and the corresponding stress carried by NbTi was evaluated as 2.53 GPa. The high volume fraction of NbTi nano lamellae improved the translation of high strength from the nano reinforced phase into bulk properties of the composite, with a platform stress of similar to 1.7 GPa and a fracture strength of similar to 1.9 GPa. (C) 2015 Elsevier B.V. All rights reserved.« less

The Effect of Nano Loading and Ultrasonic Compounding of EVA/LDPE/Nano-magnesium Hydroxide on Mechanical Properties and Distribution of Nano Particles

NASA Astrophysics Data System (ADS)

Azman, I. A.; Salleh, R. M.; Alauddin, S. M.; Shueb, M. I.

2018-05-01

Blends of Ethylene Vinyl Acetate (EVA) and Low-Density Polyethylene (LDPE) are promising composite which have good mechanical properties to environmental stress cracking. However, they lack fire resistant properties, which limits it usage in wire and cable industry. In order to improve flame retardancy ability, a range of nano-magnesium hydroxide (nano-MH) loading which is from 0 phr to maximum of 20 phr with ultrasonic extrusion 0-100 kHz frequencies have been introduced. Ultrasonic extrusion was used to improve the distribution of nano-MH. It was found that, 10 phr of nano loading with 100 kHz ultrasonic assisted has greater tensile strength compared to the nanocomposite without ultrasonication. Further increase of nano MH loading, will decrease the tensile properties. Better elongation at break was observed at10 phr nano-MH with the frequency of 50 kHz. The sample of 20 phr of nanoMH assisted with 50 kHz ultrasonic exhibits good flexural properties while 10 phr of nano-MH without the ultrasonic assisted demonstrates good in izod impact properties. From the evaluation of mechanical properties studied, it was found that 10 phr of nano-MH has shown the best performance among all the samples tested for EVA/LDPE/nano-MH composites. Transmission Electron Microscopy (TEM) has been conducted on 10 phr sample with different frequencies in order to observe the distribution of nano-MH particles. The sample with 100 kHz frequency shows more uniform dispersion of nano-MH in EVA/LDPE composites. This investigation indicates that the ultrasonic technology can enhance the mechanical properties studied as well as the dispersion of nano particles in the composite.

Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition

PubMed Central

Lu, Xiong; Zhang, Bailin; Wang, Yingbo; Zhou, Xianli; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio; Ding, Yonghui; Leng, Yang

2011-01-01

Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices. PMID:20880853

Wafer-scale aluminum nano-plasmonics

NASA Astrophysics Data System (ADS)

George, Matthew C.; Nielson, Stew; Petrova, Rumyana; Frasier, James; Gardner, Eric

2014-09-01

The design, characterization, and optical modeling of aluminum nano-hole arrays are discussed for potential applications in surface plasmon resonance (SPR) sensing, surface-enhanced Raman scattering (SERS), and surface-enhanced fluorescence spectroscopy (SEFS). In addition, recently-commercialized work on narrow-band, cloaked wire grid polarizers composed of nano-stacked metal and dielectric layers patterned over 200 mm diameter wafers for projection display applications is reviewed. The stacked sub-wavelength nanowire grid results in a narrow-band reduction in reflectance by 1-2 orders of magnitude, which can be tuned throughout the visible spectrum for stray light control.

Magnified fluorescence detection of silver(I) ion in aqueous solutions by using nano-graphite-DNA hybrid and DNase I.

PubMed

Wei, Yin; Li, Bianmiao; Wang, Xu; Duan, Yixiang

2014-08-15

This paper describes a novel approach utilizing nano-graphite-DNA hybrid and DNase I for the amplified detection of silver(I) ion in aqueous solutions for the first time. Nano-graphite can effectively quench the fluorescence of dye-labeled cytosine-rich single-stranded DNA due to its strong π-π stacking interactions; however, in the presence of Ag(+), C-Ag(+)-C coordination induces the probe to fold into a hairpin structure, which does not adsorb on the surface of nano-graphite and thus retains the dye fluorescence. Meanwhile, the hairpin structure can be cleaved by DNase I, and in such case Ag(+) is delivered from the complex. The released Ag(+) then binds other dye-labeled single-stranded DNA on the nano-graphite surface, and touches off another target recycling, resulting in the successive release of dye-labeled single-stranded DNA from the nano-graphite, which leads to significant amplification of the signal. The present magnification sensing system exhibits high sensitivity toward Ag(+) with a limit of detection of 0.3nM (S/N=3), which is much lower than the standard for Ag(+) in drinking water recommended by the Environmental Protection Agency (EPA). The selectivity of the sensor for Ag(+) against other biologically and environmentally related metal ions is outstanding due to the high specificity of C-Ag(+)-C formation. Moreover, the sensing system is used for the determination of Ag(+) in river water samples with satisfying results. The proposed assay is simple, cost-effective, and might open the door for the development of new assays for other metal ions or biomolecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Hierarchical nano-on-micro copper with enhanced catalytic activity towards electro-oxidation of hydrazine

NASA Astrophysics Data System (ADS)

Yan, Xiaodong; Liu, Yuan; Scheel, Kyle R.; Li, Yong; Yu, Yunhua; Yang, Xiaoping; Peng, Zhonghua

2018-03-01

The electrochemical properties of catalyst materials are highly dependent on the materials structure and architecture. Herein, nano-on-micro Cu electrodes are fabricated by growing Cu microcrystals on Ni foam substrate, followed by introducing Cu nanocrystals onto the surface of the Cu microcrystals. The introduction of Cu nanocrystals onto the surface of Cu microcrystals is shown to dramatically increase the electrochemically active surface area and thus significantly enhances the catalytic activity of the catalyst electrode towards electro-oxidation of hydrazine. The onset potential (-1.04 V vs. Ag/AgCl) of the nano-on-micro Cu electrode is lower than those of the reported Cu-based catalysts under similar testing conditions, and a current density of 16 mA·cm-2, which is 2 times that of the microsized Cu electrode, is achieved at a potential of -0.95 V vs. Ag/AgCl. Moreover, the nano-on-micro Cu electrode demonstrates good long-term stability.

Single-wire dye-sensitized solar cells wrapped by carbon nanotube film electrodes.

PubMed

Zhang, Sen; Ji, Chunyan; Bian, Zhuqiang; Liu, Runhua; Xia, Xinyuan; Yun, Daqin; Zhang, Luhui; Huang, Chunhui; Cao, Anyuan

2011-08-10

Conventional fiber-shaped polymeric or dye-sensitized solar cells (DSSCs) are usually made into a double-wire structure, in which a secondary electrode wire (e.g., Pt) was twisted along the primary core wire consisting of active layers. Here, we report highly flexible DSSCs based on a single wire, by wrapping a carbon nanotube film around Ti wire-supported TiO(2) tube arrays as the transparent electrode. Unlike a twisted Pt electrode, the CNT film ensures full contact with the underlying active layer, as well as uniform illumination along circumference through the entire DSSC. The single-wire DSSC shows a power conversion efficiency of 1.6% under standard illumination (AM 1.5, 100 mW/cm(2)), which is further improved to more than 2.6% assisted by a second conventional metal wire (Ag or Cu). Our DSSC wires are stable and can be bent to large angles up to 90° reversibly without performance degradation.

Single low-dose un-adjuvanted HBsAg nanoparticle vaccine elicits robust, durable immunity.

PubMed

Lugade, Amit A; Bharali, Dhruba J; Pradhan, Vandana; Elkin, Galina; Mousa, Shaker A; Thanavala, Yasmin

2013-10-01

Chitosan nanoparticles were evaluated as a vaccine delivery system for hepatitis B surface antigen (HBsAg) in the absence of adjuvant. Nano-encapsulated HBsAg (HBsAg chitosan-NP) was endocytosed more rapidly and efficiently by dendritic cells compared to soluble HBsAg. FRET analysis demonstrated that intact nanoparticles were taken up by DCs. To determine the immunogenicity of adjuvant-free nano-encapsulated HBsAg, mice were immunized with a single dose of non-encapsulated HBsAg, HBsAg chitosan-NP, or HBsAg alum. Mice immunized with adjuvant-free nanoparticle elicited anti-HBs antibodies at significantly higher titers compared to mice immunized with HBsAg alum. Elevated numbers of BAFF-R(+) B cells and CD138+ plasma cells account for the heightened anti-HBs response in nanoparticle immunized mice. Increases in Tfh cells provide a mechanism for the accumulation of anti-HBs secreting cells. Thus, chitosan nanoparticle vaccines represent a promising un-adjuvanted platform to generate robust and durable immunity to HBsAg and other subunit antigens following a single low-dose administration. In this study, chitosan nanoparticle vaccines are demonstrated as a promising un-adjuvanted platform to generate robust and durable immunity to HBsAg and other subunit antigens following a single low-dose administration in a murine model. The authors also demonstrated superior antibody response induction compared with non-encapsulated HBs antigen and HBsAg aluminum. Copyright © 2013 Elsevier Inc. All rights reserved.

Nano-silver in drinking water and drinking water sources: stability and influences on disinfection by-product formation.

PubMed

Tugulea, A-M; Bérubé, D; Giddings, M; Lemieux, F; Hnatiw, J; Priem, J; Avramescu, M-L

2014-10-01

Nano-silver is increasingly used in consumer products from washing machines and refrigerators to devices marketed for the disinfection of drinking water or recreational water. The nano-silver in these products may be released, ending up in surface water bodies which may be used as drinking water sources. Little information is available about the stability of the nano-silver in sources of drinking water, its fate during drinking water disinfection processes, and its interaction with disinfection agents and disinfection by-products (DBPs). This study aims to investigate the stability of nano-silver in drinking water sources and in the finished drinking water when chlorine and chloramines are used for disinfection and to observe changes in the composition of DBPs formed when nano-silver is present in the source water. A dispersion of nano-silver particles (10 nm; PVP-coated) was used to spike untreated Ottawa River water, treated Ottawa River water, organic-free water, and a groundwater at concentrations of 5 mg/L. The diluted dispersions were kept under stirred and non-stirred conditions for up to 9 months and analyzed weekly using UV absorption to assess the stability of the nano-silver particles. In a separate experiment, Ottawa River water containing nano-silver particles (at 0.1 and 1 mg/L concentration, respectively) was disinfected by adding sodium hypochlorite (a chlorinating agent) in sufficient amounts to maintain a free chlorine residual of approximately 0.4 mg/L after 24 h. The disinfected drinking water was then quenched with ascorbic acid and analyzed for 34 neutral DBPs (trihalomethanes, haloacetonitriles, haloacetaldehydes, 1,1 dichloro-2-propanone, 1,1,1 trichloro-2-propanone, chloropicrin, and cyanogen chloride). The results were compared to the profile of DBPs obtained under the same conditions in the absence of nano-silver and in the presence of an equivalent concentration of Ag(+) ions (as AgNO3). The stability of the nano-silver dispersions in

Attenuation of Microbial Stress Due to Nano-Ag and Nano-TiO2 Interactions under Dark Conditions.

PubMed

Wilke, Carolyn M; Tong, Tiezheng; Gaillard, Jean-François; Gray, Kimberly A

2016-10-04

Engineered nanomaterials (ENMs) are incorporated into thousands of commercial products, and their release into environmental systems creates complex mixtures with unknown toxicological outcomes. To explore this scenario, we probe the chemical and toxicological interactions of nanosilver (n-Ag) and nanotitania (n-TiO 2 ) in Lake Michigan water, a natural aqueous medium, under dark conditions. We find that the presence of n-Ag induces a stress response in Escherichia coli, as indicated by a decrease in ATP production observed at low concentrations (in the μg L -1 range), with levels that are environmentally relevant. However, when n-Ag and n-TiO 2 are present together in a mixture, n-TiO 2 attenuates the toxicity of n-Ag at and below 20 μg L -1 by adsorbing Ag + (aq) . We observe, however, that toxic stress cannot be explained by dissolved silver concentrations alone and, therefore, must also depend on silver associated with the nanoscale fraction. Although the attenuating effect of n-TiO 2 on n-Ag's toxicity is limited, this study emphasizes the importance of probing the toxicity of ENM mixtures under environmental conditions to assess how chemical interactions between nanoparticles change the toxicological effects of single ENMs in unexpected ways.

Antimicrobial nano-silver non-woven polyethylene terephthalate fabric via an atmospheric pressure plasma deposition process

PubMed Central

Deng, Xiaolong; Yu Nikiforov, Anton; Coenye, Tom; Cools, Pieter; Aziz, Gaelle; Morent, Rino; De Geyter, Nathalie; Leys, Christophe

2015-01-01

An antimicrobial nano-silver non-woven polyethylene terephthalate (PET) fabric has been prepared in a three step process. The fabrics were first pretreated by depositing a layer of organosilicon thin film using an atmospheric pressure plasma system, then silver nano-particles (AgNPs) were incorporated into the fabrics by a dipping-dry process, and finally the nano-particles were covered by a second organosilicon layer of 10-50 nm, which acts as a barrier layer. Different surface characterization techniques like SEM and XPS have been implemented to study the morphology and the chemical composition of the nano-silver fabrics. Based on these techniques, a uniform immobilization of AgNPs in the PET matrix has been observed. The antimicrobial activity of the treated fabrics has also been tested using P. aeruginosa, S. aureus and C. albicans. It reveals that the thickness of the barrier layer has a strong effect on the bacterial reduction of the fabrics. The durability and stability of the AgNPs on the fabrics has also been investigated in a washing process. By doing so, it is confirmed that the barrier layer can effectively prevent the release of AgNPs and that the thickness of the barrier layer is an important parameter to control the silver ions release. PMID:25951432

Direct in situ observation of the electron-driven synthesis of Ag filaments on α-Ag2WO4 crystals

PubMed Central

Longo, E.; Cavalcante, L. S.; Volanti, D. P.; Gouveia, A. F.; Longo, V. M.; Varela, J. A.; Orlandi, M. O.; Andrés, J.

2013-01-01

In this letter, we report, for the first time, the real-time in situ nucleation and growth of Ag filaments on α-Ag2WO4 crystals driven by an accelerated electron beam from an electronic microscope under high vacuum. We employed several techniques to characterise the material in depth. By using these techniques combined with first-principles modelling based on density functional theory, a mechanism for the Ag filament formation followed by a subsequent growth process from the nano- to micro-scale was proposed. In general, we have shown that an accelerated electron beam from an electronic microscope under high vacuum enables in situ visualisation of Ag filaments with subnanometer resolution and offers great potential for addressing many fundamental issues in materials science, chemistry, physics and other fields of science. PMID:23591807

Composite ceramic superconducting wires for electric motor applications

NASA Astrophysics Data System (ADS)

Halloran, John W.

1990-07-01

Several types of HTSC wire have been produced and two types of HTSC motors are being built. Hundreds of meters of Ag- clad wire were fabricated from YBa2Cu3O(7-x) (Y-123) and Bi2Ca2Sr2Cu3O10 (BiSCCO). The dc homopolar motor coils are not yet completed, but multiple turns of wire have been wound on the coil bobbins to characterize the superconducting properties of coiled wire. Multifilamentary conductors were fabricated as cables and coils. The sintered polycrystalline wire has self-field critical current densities (Jc) as high as 2800 A/sq cm, but the Jc falls rapidly with magnetic field. To improve Jc, sintered YBCO wire is melt textured with a continuous process which has produced textures wire up to 0.5 meters long with 77K transport Jc above 11, 770 A/sq cm2 in self field and 2100 A/sq cm2 at 1 telsa. The Emerson Electric dc homopolar HTSC motor has been fabricated and run with conventional copper coils. A novel class of potential very powerful superconducting motors have been designed to use trapped flux in melt textures Y-123 as magnet replicas in an new type of permanent magnet motor. The stator element and part of the rotor of the first prototype machine exist, and the HTSC magnet replica segments are being fabricated.

Superconducting properties of nano-sized SiO2 added YBCO thick film on Ag substrate

NASA Astrophysics Data System (ADS)

Almessiere, Munirah Abdullah; Al-Otaibi, Amal lafy; Azzouz, Faten Ben

2017-10-01

The microstructure and the flux pinning capability of SiO2-added YBa2Cu3Oy thick films on Ag substrates were investigated. A series of YBa2Cu3Oy thick films with small amounts (0-0.5 wt%) of nano-sized SiO2 particles (12 nm) was prepared. The thicknesses of the prepared thick films was approximately 100 µm. Phase analysis by x-ray diffraction and microstructure examination by scanning electron microscopy were performed and the critical current density dependence on the applied magnetic field Jc(H) and electrical resistivity ρ(T) were investigated. The magnetic field and temperature dependence of the critical current density (Jc) was calculated from magnetization measurements using Bean's critical state model. The results showed that the addition of a small amount (≤0.02 wt%) of SiO2 was effective in enhancing the critical current densities in the applied magnetic field. The sample with 0.01 wt% of added SiO2 exhibited a superconducting characteristics under an applied magnetic field for a temperature ranging from 10 to 77 K.

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

PubMed Central

Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Yang, Qiuhong; Zhou, Chunlin; Zhang, Pande; Mao, Xiaojian; Zhang, Long

2015-01-01

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders. PMID:28793510

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method.

PubMed

Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Yang, Qiuhong; Zhou, Chunlin; Zhang, Pande; Mao, Xiaojian; Zhang, Long

2015-08-19

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.

Formation of Ag nanoframes with facilitation of dithiols.

PubMed

Cheng, Fong-Yu; Hu, Kuo-Wei; Yeh, Chen-Sheng

2012-03-01

Two-dimensional Ag nanoprisms readily formed Ag triangular nanoframes upon electron beam irradiation. Following meso-2, 3-dimercaptosuccinicacid (DMSA) ripening behavior, continuous electron beam exposure transformed a solid nanoplate into a core/void/shell morphology, which then evolved into a hollow nanoframe structure. TEM was used to observe the ripening and etching processes of Ag nanoprisms as a function of DMSA concentration and electron irradiation time. X-ray diffraction (XRD) and FT-IR analysis were conducted to characterize the Ag nanoprism structure and surface before and after treatment with DMSA. X-ray photoelectron spectroscopy (XPS) was used to determine surface chemical compositions and indicated DMSA was adsorbed on the Ag nanoprisms in the form of Ag(+)-S(-). Raman measurements provided evidence of a disulfide group on Ag nanoprisms. Similar organosulfur structures such as mercaptosuccinic acid and 2-mercaptoacetic acid were also studied with results suggesting that the two S-H groups of dithiol DMSA played the crucial role in nanoframe fabrication. Using the same strategy with DMSA, the nano-architecture can be extended to 2D nanodiscs yielding nanorings.

Characterization of Antimicrobial Poly (Lactic Acid)/Nano-Composite Films with Silver and Zinc Oxide Nanoparticles

PubMed Central

Chu, Zhuangzhuang; Zhao, Tianrui; Li, Lin; Fan, Jian; Qin, Yuyue

2017-01-01

Antimicrobial active films based on poly (lactic acid) (PLA) were prepared with nano-silver (nano-Ag) and nano-zinc oxide (nano-ZnO) using a solvent volatilizing method. The films were characterized for mechanical, structural, thermal, physical and antimicrobial properties. Scanning electron microscopy (SEM) images characterized the fracture morphology of the films with different contents of nano-Ag and nano-ZnO. The addition of nanoparticles into the pure PLA film decreased the tensile strength and elasticity modulus and increased the elongation of breaks—in other words, the flexibility and extensibility of these composites improved. According to the results of differential scanning calorimetry (DSC), the glass transition temperature of the PLA nano-composite films decreased, and the crystallinity of these films increased; a similar result was apparent from X-ray diffraction (XRD) analysis. The water vapor permeability (WVP) and opacity of the PLA nano-composite films augmented compared with pure PLA film. Incorporation of nanoparticles to the PLA films significantly improved the antimicrobial activity to inhibit the growth of Escherichia coli. The results indicated that PLA films with nanoparticles could be considered a potential environmental-friendly packaging material. PMID:28773018

Fabrication of metal/semiconductor nanocomposites by selective laser nano-welding.

PubMed

Yu, Huiwu; Li, Xiangyou; Hao, Zhongqi; Xiong, Wei; Guo, Lianbo; Lu, Yongfeng; Yi, Rongxing; Li, Jiaming; Yang, Xinyan; Zeng, Xiaoyan

2017-06-01

A green and simple method to prepare metal/semiconductor nanocomposites by selective laser nano-welding metal and semiconductor nanoparticles was presented, in which the sizes, phases, and morphologies of the components can be maintained. Many types of nanocomposites (such as Ag/TiO 2 , Ag/SnO 2 , Ag/ZnO 2 , Pt/TiO 2 , Pt/SnO 2 , and Pt/ZnO) can be prepared by this method and their corresponding performances were enhanced.

A highly efficient nano-cluster artificial peroxidase and its direct electrochemistry on a nano complex modified glassy carbon electrode.

PubMed

Hong, Jun; Wang, Wei; Huang, Kun; Yang, Wei-Yun; Zhao, Ying-Xue; Xiao, Bao-Lin; Gao, Yun-Fei; Moosavi-Movahedi, Zainab; Ghourchian, Hedayatollah; Moosavi-Movahedi, Ali Akbar

2012-01-01

A nano-cluster with highly efficient peroxide activity was constructed based on nafion (NF) and cytochrome c (Cyt c). UV-Vis spectrometry and transmission electron microscopy (TEM) methods were utilized for characterization of the nano-structured enzyme or artificial peroxidase (AP). The nano-cluster was composed of a Chain-Ball structure, with an average ball size of about 40 nm. The Michaelis-Menten (K(m)) and catalytic rate (k(cat)) constants of the AP were determined to be 2.5 ± 0.4 µM and 0.069 ± 0.001 s(-1), respectively, in 50 mM PBS at pH 7.0. The catalytic efficiency of the AP was evaluated to be 0.028 ± 0.005 µM(-1) s(-1), which was 39 ± 5% as efficient as the native horseradish peroxidase (HRP). The AP was also immobilized on a functional multi-wall carbon nanotube (MWNCTs)-gold colloid nanoparticles (AuNPs) nano-complex modified glassy carbon (GC) electrode. The cyclic voltammetry of AP on the nano complex modified GC electrode showed a pair of well-defined redox peaks with a formal potential (E°') of -45 ± 2 mV (vs. Ag/AgCl) at a scan rate of 0.05 V/s. The heterogeneous electron transfer rate constant (k(s)) was evaluated to be 0.65 s(-1). The surface concentration of electroactive AP on GC electrode (Γ) was 7 × 10(-10) mol cm(-2). The apparent Michaelis-Menten constant (K(m)(app)) was 0.23 nM.

Two-stage epitaxial growth of vertically-aligned SnO 2 nano-rods on(001) ceria

DOE PAGES

Solovyov, Vyacheslav F.; Wu, Li-jun; Rupich, Martin W.; ...

2014-09-20

Growth of high-aspect ratio oriented tin oxide, SnO 2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO 2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO 2 deposit. Second, vertical SnO 2nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 μm long nano-rods with an average diameter of ≈20 nm.

Influence of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires

NASA Astrophysics Data System (ADS)

Asiry, Moshabab A.; AlShahrani, Ibrahim; Almoammar, Salem; Durgesh, Bangalore H.; Kheraif, Abdulaziz A. Al; Hashem, Mohamed I.

2018-02-01

Aim. To investigate the effect of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires Methods. Three different coated (Epoxy, polytetrafluoroethylene (PTFE) and rhodium) and one uncoated Ni-Ti archwires were evaluated in the present study. Surface roughness (Ra) was assessed using a non-contact surface profilometer. The mechanical properties (nano-hardness and elastic modulus) were measured using a nanoindenter. Bacterial adhesion assays were performed using Streptococcus mutans (MS) and streptococcus sobrinus (SS) in an in-vitro set up. The data obtained were analyzed using analyses of variance, Tukey’s post hoc test and Pearson’s correlation coefficient test. Result. The highest Ra values (1.29 ± 0.49) were obtained for epoxy coated wires and lowest Ra values (0.29 ± 0.16) were obtained for the uncoated wires. No significant differences in the Ra values were observed between the rhodium coated and uncoated archwires (P > 0.05). The highest nano-hardness (3.72 ± 0.24) and elastic modulus values (61.15 ± 2.59) were obtained for uncoated archwires and the lowest nano-hardness (0.18 ± 0.10) and elastic modulus values (4.84 ± 0.65) were observed for epoxy coated archwires. No significant differences in nano-hardness and elastic modulus values were observed between the coated archwires (P > 0.05). The adhesion of Streptococcus mutans (MS) to the wires was significantly greater than that of streptococcus sobrinus (SS). The epoxy coated wires demonstrated an increased adhesion of MS and SS and the uncoated wires demonstrated decreased biofilm adhesion. The Spearman correlation test showed that MS and SS adhesion was positively correlated with the surface roughness of the wires. Conclusion. The different surface coatings significantly influence the roughness, nano-mechanical properties and biofilm adhesion parameters of the archwires. The

Formation of Ag nanoparticles and enhancement of Tb3+ luminescence in Tb and Ag co-doped lithium-lanthanum-aluminosilicate glass

NASA Astrophysics Data System (ADS)

Piasecki, Patryk; Piasecki, Ashley; Pan, Zhengda; Mu, Richard; Morgan, Steven H.

2010-12-01

Tb3+ and Ag co-doped glass nano-composites were synthesized in a glass matrix Li2O-LaF3-Al2O3-SiO2 (LLAS) by a melt-quench technique. The growth of Ag nanoparticles (NPs) was controlled by a thermal annealing process. A broad absorption band peaking at about 420 nm was observed due to surface plasmon resonance (SPR) of Ag NPs. The intensity of this band grows with increasing annealing time. The transmission electron microscopic image (TEM) reveals the formation of Ag NPs in glass matrix. Photoluminescence (PL) emission and excitation spectra were measured for glass samples with different Ag concentrations and different annealing times. Plasmon enhanced Tb3+ luminescence was observed at certain excitation wavelength regions. Luminescence quenching was also observed for samples with high Ag concentration and longer annealing time. Our luminescence results suggest that there are two competitive effects, enhancement and quenching, acting on Tb3+ luminescence in the presence of Ag NPs. The enhancement of Tb3+ luminescence is mainly attributed to local field effects due to SPR. The quenching of luminescence suggests an energy transfer from Tb3+ ions to Ag NPs.

Static strain tuning of quantum dots embedded in a photonic wire

NASA Astrophysics Data System (ADS)

Tumanov, D.; Vaish, N.; Nguyen, H. A.; Curé, Y.; Gérard, J.-M.; Claudon, J.; Donatini, F.; Poizat, J.-Ph.

2018-03-01

We use strain to statically tune the semiconductor band gap of individual InAs quantum dots (QDs) embedded in a GaAs photonic wire featuring very efficient single photon collection. Thanks to the geometry of the structure, we are able to shift the QD excitonic transition by more than 25 meV by using nano-manipulators to apply the stress. Moreover, owing to the strong transverse strain gradient generated in the structure, we can relatively tune two QDs located in the wire waveguide and bring them in resonance, opening the way to the observation of collective effects such as superradiance.

[Study on the antibacterial activity of four kinds of nano-hydroxyapatite composites against Enterococcus faecalis].

PubMed

Liu, Yi; Zhou, Rongjing; Wu, Hongkun

2015-06-01

This study aims to compare and determine a kind of nano-hydroxyapatite composite material with good antibacterial efficacy on Enterococcusfaecalis (E. faecalis) in vitro. We investigated the antimicrobial activity of four kinds of nano-hydroxyapatite composites, namely, silver/hydroxyapatite composite nanoparticles (Ag/nHA), yttrium/hydroxyapatite composite nanoparticles (Yi/nHA), cerium/hydroxyapatite composite nanoparticles (Ce/nHA), and hydroxyapatite nanoparticles (nHA), against E. faecalis in vitro using the agar diffusion and broth dilution method by measuring the growth inhibition zone and the minimum inhibitory concentration (MIC), respectively. The agar diffusion test results showed that Ag/nHA displayed an obvious growth inhibition zone, whereas Yi/nHA, Ce/nHA, and nHA showed no influence on E. faecalis. The MIC value of Ag/nHA was 1.0 g.L-1, and the three other materials had no effect on E.faecalis even at the high concentration of 32.0 g.L-1. Ag/nHA display a potential antimicrobial efficacy to planktonic E.faecalis. Whereas, the three other kinds of nano-hydroxyapatite composites (Yi/nHA, Ce/nHA, nHA) show no influence.

Low-haze, annealing-free, very long Ag nanowire synthesis and its application in a flexible transparent touch panel

NASA Astrophysics Data System (ADS)

Moon, Hyunjin; Won, Phillip; Lee, Jinhwan; Ko, Seung Hwan

2016-07-01

Since transparent conducting films based on silver nanowires (AgNWs) have shown higher transmittance and electrical conductivity compared to those of indium tin oxide (ITO) films, the electronics industry has recognized them as promising substitutes. However, due to the higher haze value of AgNW transparent conducting films compared to ITO films, the clarity is decreased when AgNW films are applied to optoelectronic devices. In this study, we develop a highly transparent, low-haze, very long AgNW percolation network. Moreover, we confirm that analyzed chemical roles can easily be applied to different AgNW synthesis methods, and that they have a direct impact on the nanowire shape. Consequently, the lengths of the wires are increased up to 200 μm and the diameters of the wires are decreased up to 45 nm. Using these results, we fabricate highly transparent (96%) conductors (100 Ω/sq) with low-haze (2%) without any annealing process. This electrode shows enhanced clarity compared to previous results due to the decreased diffusive transmittance and scattering. In addition, a flexible touchscreen using a AgNW network is demonstrated to show the performance of modified AgNWs.

Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001) ceria

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

Solovyov, VF; Wu, LJ; Rupich, MW

2014-12-15

Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2 nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 mu m long nano-rods with an average diameter of approximate to 20 nm. 2014 Elsevier B.V. All rights reserved.

Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash.

PubMed

Tahmasbi, Soodeh; Ghorbani, Mohammad; Masudrad, Mahdis

2015-01-01

Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various manufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022" Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye). These brackets along with stainless steel (SS) or nickel-titanium (NiTi) orthodontic wires (0.016", round) were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP) difference of each bracket-wire couple was measured with a Saturated Calomel Reference Electrode (Ag/AgCl saturated with KCl) via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and specimens with corrosion were analyzed with scanning electron microscopy (SEM). Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P < 0.05). Corrosion rate of brackets coupled with NiTi wires was higher than that of brackets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recommended when using them.

Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash

PubMed Central

Tahmasbi, Soodeh; Ghorbani, Mohammad; Masudrad, Mahdis

2015-01-01

Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various manufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022" Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye). These brackets along with stainless steel (SS) or nickel-titanium (NiTi) orthodontic wires (0.016", round) were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP) difference of each bracket-wire couple was measured with a Saturated Calomel Reference Electrode (Ag/AgCl saturated with KCl) via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and specimens with corrosion were analyzed with scanning electron microscopy (SEM). Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P < 0.05). Corrosion rate of brackets coupled with NiTi wires was higher than that of brackets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recommended when using them. PMID:26697148

Characterization and antimicrobial performance of nano silver coatings on leather materials

PubMed Central

Lkhagvajav, N.; Koizhaiganova, M.; Yasa, I.; Çelik, E.; Sari, Ö.

2015-01-01

In this study, the characterization and the antimicrobial properties of nano silver (nAg) coating on leather were investigated. For this purpose, turbidity, viscosity and pH of nAg solutions prepared by the sol-gel method were measured. The formation of films from these solutions was characterized according to temperature by Differential Thermal Analysis-Thermogravimetry (DTA-TG) equipment. The surface morphology of treated leathers was observed using Scanning Electron Microscopy (SEM). The antimicrobial performance of nAg coatings on leather materials to the test microorganisms as Escherichia coli , Staphylococcus aureus , Candida albicans and Aspergillius niger was evaluated by the application of qualitative (Agar overlay method) and quantitative (percentage of microbial reduction) tests. According to qualitative test results it was found that 20 μg/cm 2 and higher concentrations of nAg on the leather samples were effective against all microorganisms tested. Moreover, quantitative test results showed that leather samples treated with 20 μg/cm 2 of nAg demonstrated the highest antibacterial activity against E. coli with 99.25% bacterium removal, whereas a 10 μg/cm 2 concentration of nAg on leather was enough to exhibit the excellent percentage reduction against S. aureus of 99.91%. The results are promising for the use of colloidal nano silver solution on lining leather as antimicrobial coating. PMID:26221087

A simple approach for large-area fabrication of Ag nanorings

NASA Astrophysics Data System (ADS)

Yuan, Zhi-hao; Zhou, Wei; Duan, Yue-qin; Bie, Li-jian

2008-02-01

A simple and low-cost method based on a two-step heat treatment of AgNO3/SiO2 film has been developed for fabricating metal Ag nanoring arrays. The as-prepared nanorings have an inner diameter of 70-250 nm and an average wall thickness (namely wire diameter) of approximately 30 nm with a number density of approximately 109 cm-2 on the surface of the SiO2 matrix. X-ray diffraction (XRD) results reveal that these nanorings exhibit a face-centered cubic crystal structure. Furthermore, a new growth mechanism, namely a molten metal bubble as a self-template, is tentatively proposed for Ag nanorings.

The facile synthesis of chitosan-based silver nano-biocomposites via a solution plasma process and their potential antimicrobial efficacy.

PubMed

Davoodbasha, MubarakAli; Kim, Seong-Cheol; Lee, Sang-Yul; Kim, Jung-Wan

2016-09-01

Silver nanoparticles (AgNPs) were synthesized in a chitosan matrix with varying AgNO3 (1, 3, 5 mM) and chitosan (1, 3%) concentrations via the one-step solution plasma process (SPP). Plasma was discharged for 3 min in the AgNO3 and chitosan solutions using unipolar power at 800 V with a frequency of 30 kHz. Fibrous 3D scaffolds were prepared by lyophilizing the nano-biocomposite solutions, and they were stabilized via cross-linking with UV irradiation. UV-Vis spectroscopy showed strong peaks with maximal absorbance at 415-440 nm, indicating the formation of AgNPs in the chitosan with an increase in peak height as the concentration of the precursor, AgNO3, increased. The chemical association between AgNPs and chitosan was confirmed using Fourier transform infrared spectroscopy (FTIR). The scaffolds had a micro-porous structure with pore diameters in the range of 5.8-157.0 μm, and a transmission electron microscopy (TEM) analysis revealed that spherical shaped AgNPs with diameters in the range of 2.5-27.6 nm were well-dispersed in the biocomposites. The nano-biocomposites had a broad spectrum of antimicrobial activity against various pathogens with minimal inhibition concentrations of 0.68-2.71 and 2.71-10.80 μg mL(-1) for bacteria and fungi, respectively. These are the lowest concentrations achieved by nano-biocomposites reported thus far. The SPP was shown to be a facile, effective, and eco-friendly method of synthesizing nano-biocomposites for biomedical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

SERS activity studies of Ag/Au bimetallic films prepared by galvanic replacement

NASA Astrophysics Data System (ADS)

Wang, Chaonan; Fang, Jinghuai; Jin, Yonglong

2012-10-01

Ag films on Si substrates were fabricated by immersion plating, which served as sacrificial materials for preparation of Ag/Au bimetallic films by galvanic replacement method. SEM images displayed that the sacrificial Ag films presenting island morphology experienced interesting structural evolution process during galvanic replacement reaction, and nano-scaled holes were formed in the resultant bimetallic films. SERS measurements using crystal violet as an analyte showed that SERS intensities of bimetallic films were enhanced significantly compared with that of pure Ag films and related mechanisms were discussed. Immersion plating experiment carried out on Ag films on PEN substrates fabricated by photoinduced reduction method further confirmed that galvanic replacement is an easy method to fabricate Ag/Au bimetallic and a potential approach to improve the SERS performance of Ag films.

Seeded Nanowire and Microwire Growth from Lithium Alloys.

PubMed

Han, Sang Yun; Boebinger, Matthew G; Kondekar, Neha P; Worthy, Trevor J; McDowell, Matthew T

2018-06-06

Although vapor-liquid-solid (VLS) growth of nanowires from alloy seed particles is common in various semiconductor systems, related wire growth in all-metal systems is rare. Here, we report the spontaneous growth of nano- and microwires from metal seed particles during the cooling of Li-rich bulk alloys containing Au, Ag, or In. The as-grown wires feature Au-, Ag-, or In-rich metal tips and LiOH shafts; the results indicate that the wires grow as Li metal and are converted to polycrystalline LiOH during and/or after growth due to exposure to H 2 O and O 2 . This new process is a simple way to create nanostructures, and the findings suggest that metal nanowire growth from alloy seeds is possible in a variety of systems.

Evaluation of corrosion resistance and surface characteristics of orthodontic wires immersed in different mouthwashes.

PubMed

Nalbantgil, Didem; Ulkur, Feyza; Kardas, Gulfeza; Culha, Mustafa

2016-11-25

Patients use mouthwashes in addition to mechanical cleaning during orthodontic treatment. The effects of mouthwashes on the archwires have not been examined yet. To compare the corrosion resistance of four different arch wires and corrosion effects of different mouthwashes to formulate a biocompatible and mechanically useful arch wire and mouthwash combination. Each group comprised of 4 wire samples of 2 cm 0.016 × 0.022 inch. 1st group: ion implanted nickel titanium (INT), 2nd group: nickel titanium, without ion implantation (NT), 3rd group: micro layered esthetic nickel titanium (ENT), 4th group: stainless steel (SS) wires. They were immersed inside 2 ml of artificial saliva solutions (AS) for the control, or AS (9%) combined with 1 of the 3 mouthwashes (91%) for study groups, for 24 hours. These mouthwashes were essential oil (EO), chlorhexidine (CHX), sodium-fluoride (NaF). An electrochemical analyzer was used for electrochemical impedance spectroscopy measurements. High corrosion resistance was obtained for ENT than the other wires. The corrosion potentials are 0.007, -0.042, 0.074 and -0.015 V (Ag/AgCl) for ENT, INT, SS and NT in the artificial salivary, respectively. In NaF containing mouthwash Rp value of ENT is significantly high in comparison to others. The impedance responses of all materials increased significantly in the presence of NaF mouthwash as well as in the CHX mouthwash. Low frequencies are seen at all materials in EO mouthwash. Diameters of loops are 22, 5.9, 5.9 and 3.7 MΩ at ENT, INT, SS and NT. In this study, micro layered esthetic nickel titanium wires are found biocompatible among other wires and NaF and CHX mouthwashes can be recommend for their good corrosion resistance during fixed orthodontic therapy.

Magnetization Analysis of Magnesium Boride Wires

NASA Astrophysics Data System (ADS)

Cave, J. R.; Zhu, W.

2006-03-01

Cycled applied field magnetization curves contain a wealth of information on critical current density and flux pinning that is not commonly exploited. Detailed magnetization data for magnesium boride wire cores have been analyzed for critical state model consistency. The iron-sheathed silicon nitride doped magnesium boride wires were prepared from pure magnesium and boron powders with nano-scale silicon nitride additions (MgB2-x(Si3N4)x/7 with x = 0 - 0.4). A subsequent short annealing heat treatment, 800 degrees C and of 1 hour duration in Argon, was applied to create the desired phase. Magnetization critical current densities were up to ˜340 kA/cm2 at 5K and 1T. Major and minor loop analysis will be described, for field sweeps up to 3 tesla at fixed temperatures and for temperature sweeps from 5K to 45K in fixed fields, with respect to parameters describing the critical state model.

Titanium bone implants with superimposed micro/nano-scale porosity and antibacterial capability

NASA Astrophysics Data System (ADS)

Necula, B. S.; Apachitei, I.; Fratila-Apachitei, L. E.; van Langelaan, E. J.; Duszczyk, J.

2013-05-01

This study aimed at producing a multifunctional layer with micro/nano-interconnected porosity and antibacterial capability on a rough macro-porous plasma sprayed titanium surface using the plasma electrolytic oxidation process. The layers were electrochemically formed in electrolytes based on calcium acetate and calcium glycerophosphate salts bearing dispersed Ag nanoparticles. They were characterized with respect to surface morphology and chemical composition using a scanning electron microscope equipped with the energy dispersive spectroscopy and back scattering detectors. Scanning electron microscopy images showed the formation of a micro/nano-scale porous layer, comprised of TiO2 bearing Ca and P species and Ag nanoparticles, following accurately the surface topography of the plasma sprayed titanium coating. The Ca/P atomic ratio was found to be close to that of bone apatite. Ag nanoparticles were incorporated on both on top and inside the porous structure of the TiO2 layer.

Laser Indirect Shock Welding of Fine Wire to Metal Sheet

PubMed Central

Wang, Xiao; Huang, Tao; Luo, Yapeng; Liu, Huixia

2017-01-01

The purpose of this paper is to present an advanced method for welding fine wire to metal sheet, namely laser indirect shock welding (LISW). This process uses silica gel as driver sheet to accelerate the metal sheet toward the wire to obtain metallurgical bonding. A series of experiments were implemented to validate the welding ability of Al sheet/Cu wire and Al sheet/Ag wire. It was found that the use of a driver sheet can maintain high surface quality of the metal sheet. With the increase of laser pulse energy, the bonding area of the sheet/wire increased and the welding interfaces were nearly flat. Energy dispersive spectroscopy (EDS) results show that the intermetallic phases were absent and a short element diffusion layer which would limit the formation of the intermetallic phases emerging at the welding interface. A tensile shear test was used to measure the mechanical strength of the welding joints. The influence of laser pulse energy on the tensile failure modes was investigated, and two failure modes, including interfacial failure and failure through the wire, were observed. The nanoindentation test results indicate that as the distance to the welding interface decreased, the microhardness increased due to the plastic deformation becoming more violent. PMID:28895900

Laser Indirect Shock Welding of Fine Wire to Metal Sheet.

PubMed

Wang, Xiao; Huang, Tao; Luo, Yapeng; Liu, Huixia

2017-09-12

The purpose of this paper is to present an advanced method for welding fine wire to metal sheet, namely laser indirect shock welding (LISW). This process uses silica gel as driver sheet to accelerate the metal sheet toward the wire to obtain metallurgical bonding. A series of experiments were implemented to validate the welding ability of Al sheet/Cu wire and Al sheet/Ag wire. It was found that the use of a driver sheet can maintain high surface quality of the metal sheet. With the increase of laser pulse energy, the bonding area of the sheet/wire increased and the welding interfaces were nearly flat. Energy dispersive spectroscopy (EDS) results show that the intermetallic phases were absent and a short element diffusion layer which would limit the formation of the intermetallic phases emerging at the welding interface. A tensile shear test was used to measure the mechanical strength of the welding joints. The influence of laser pulse energy on the tensile failure modes was investigated, and two failure modes, including interfacial failure and failure through the wire, were observed. The nanoindentation test results indicate that as the distance to the welding interface decreased, the microhardness increased due to the plastic deformation becoming more violent.

Reduced graphene oxide wrapped Ag nanostructures for enhanced SERS activity

NASA Astrophysics Data System (ADS)

Nair, Anju K.; Kala, M. S.; Thomas, Sabu; Kalarikkal, Nandakumar

2018-04-01

Graphene - metal nanoparticle hybrids have received great attention due to their unique electronic properties, large specific surface area, very high conductivity and more charge transfer. Thus, it is extremely advantages to develop a simple and efficient process to disperse metal nanostructures over the surface of graphene sheets. Herein, we report a hydrothermal assisted strategy for developing reduced graphene oxide /Ag nanomorphotypes (cube, wire) for surface enhanced Raman scattering (SERS) applications, considering the advantages of synergistic effect of graphene and plasmonic properties of Ag nanomorphotypes.

Applying Taguchi design and large-scale strategy for mycosynthesis of nano-silver from endophytic Trichoderma harzianum SYA.F4 and its application against phytopathogens

NASA Astrophysics Data System (ADS)

El-Moslamy, Shahira H.; Elkady, Marwa F.; Rezk, Ahmed H.; Abdel-Fattah, Yasser R.

2017-03-01

Development of reliable and low-cost requirement for large-scale eco-friendly biogenic synthesis of metallic nanoparticles is an important step for industrial applications of bionanotechnology. In the present study, the mycosynthesis of spherical nano-Ag (12.7 ± 0.8 nm) from extracellular filtrate of local endophytic T. harzianum SYA.F4 strain which have interested mixed bioactive metabolites (alkaloids, flavonoids, tannins, phenols, nitrate reductase (320 nmol/hr/ml), carbohydrate (25 μg/μl) and total protein concentration (2.5 g/l) was reported. Industrial mycosynthesis of nano-Ag can be induced with different characters depending on the fungal cultivation and physical conditions. Taguchi design was applied to improve the physicochemical conditions for nano-Ag production, and the optimum conditions which increased its mass weight 3 times larger than a basal condition were as follows: AgNO3 (0.01 M), diluted reductant (10 v/v, pH 5) and incubated at 30 °C, 200 rpm for 24 hr. Kinetic conversion rates in submerged batch cultivation in 7 L stirred tank bioreactor on using semi-defined cultivation medium was as follows: the maximum biomass production (Xmax) and maximum nano-Ag mass weight (Pmax) calculated (60.5 g/l and 78.4 g/l respectively). The best nano-Ag concentration that formed large inhibition zones was 100 μg/ml which showed against A.alternate (43 mm) followed by Helminthosporium sp. (35 mm), Botrytis sp. (32 mm) and P. arenaria (28 mm).

The Nano-filters as the tools for the management of the water imbalance in the human society

NASA Astrophysics Data System (ADS)

Singh, R. P.; Kontar, V.

2011-12-01

The imbalance of water in the human society there is some situation where the water demand is not equivalent to the water supply. We are talking now about the shortage of some clear water which suitable for human use, animals, plants, technologies etc. There are existing some various imbalances of water in the human society, but about this will be other publications. The humanity has have the millennial experience of the water imbalance management. The novelty of the matter is the new nano-materials which offer a lot of the new principles more effective management of the water imbalance in the human society. The nano-materials have typical pore size 0.001 micron (1 nano-meter). There are some metal-containing nano-particles, CNTs, fullerene, graphene, zeolites and dendrimers etc, The nano-materials have unique physicochemical properties due to their large surface areas, size and shape-dependent optical, electronic, and catalytic properties that make them very useful for separation components some various stuff and water also. They have ability to functionalize with various chemical groups to increase their affinity toward a desired compound. The silver nano-wires have established a variety of applications, including transparent conductive electrodes for solar cells and optoelectronic. The salt of silver i.e. bulk silver shows photo-catalytic properties. The gold decorated silver nano-wires film may clean the organic molecule while irradiated with either commercial bulb or sun light. The mat (membrane) papers of nano-wires may clean up spilled oil at sea and organic pollutants in water. Arsenic-poisoned drinking water is a global problem, affecting people in Asia, Africa, North America, South America and Europe. Tiny bits of iron oxide that are smaller than living cells known as nanorust, which naturally binds with arsenic, could be used as a low-cost means of removing arsenic from water. Nano-tea bag purifies water on a small scale. The sachets are made up from the

Nano-photo active cellulosic fabric through in situ phytosynthesis of star-like Ag/ZnO nanocomposites: Investigation and optimization of attributes associated with photocatalytic activity.

PubMed

Aladpoosh, Razieh; Montazer, Majid

2016-05-05

In this study, nano-photo active cellulosic fabric was prepared through in situ phytosynthesis of star-like Ag/ZnO nanocomposites using the ashes of Seidlitzia rosmarinus plants so-called Keliab. This is provided alkali media as a vital condition for synthesis of nanocomposites, further increasing the reduce-ability of cellulosic chains by activation of hydroxyl groups. The intermolecular dehydrolysis of intermediates ions under thermal and alkaline conditions leads to formation of Ag/ZnO heterostructure. Various analytical techniques were employed to confirm Ag/ZnO nanocomposites on the cotton fabric. The surface morphology, crystal phase and chemical structure of the treated fabrics were characterized by field emission and scanning electron microscopy (FE-SEM and SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX). Moreover, influence of precursors: silver nitrate, zinc acetate and Keliab solution on attributes associated with photocatalytic activities including self-cleaning, whiteness and wettability was investigated via central composite design (CCD). The treated cotton samples exhibited self-cleaning activities through methylene blue degradation under day-light exposure along with improved wettability and whiteness. The prepared sample in optimized conditions showed good antibacterial activities against Staphylococcus aureus and Escherichia coli with enhanced fabric tensile strength. Copyright © 2016 Elsevier Ltd. All rights reserved.

A biomimetic nano hybrid coating based on the lotus effect and its anti-biofouling behaviors

NASA Astrophysics Data System (ADS)

Li, Jiang; Wang, Guoqing; Meng, Qinghua; Ding, Chunhua; Jiang, Hong; Fang, Yongzeng

2014-10-01

To develop an environmentally friendly anti-biofouling coating in virtue of bionics, a block copolymer containing fluorine (Coplm_F) of low surface energy was prepared by copolymerization. The Ag-loaded mesoporous silica (Ag@SBA) acting as a controlled-release antifoulant was prepared from the mesoporous silica (SBA-15). The nano hybrid coating (Ag@SBA/Coplm_F) composing of the Coplm_F and Ag@SBA was to biomimetically simulate the lotus microstructure. The concentration of fluorine element on surface was analyzed by the energy dispersive spectroscopy (EDS) and found rising to 1.45% after hybridation, which could be explained by the driving effect of SBA-15 via the hydrogen bond. This nanoscale morphology of the hybrid coating was measured and found highly semblable to the microstructure of the lotus surface. The contact angle was determined as 151° which confirmed the superhydrophobicity and lotus effect. The adhesion behaviors of Pseudomonas fluorescens, Diatoms, and Chlorella on the surface of the nano hybrid coating (Ag@SBA/Coplm_F) were studied and good effects of anti-biofouling were observed.

An EEG (electroencephalogram) recording system with carbon wire electrodes for simultaneous EEG-fMRI (functional magnetic resonance imaging) recording

PubMed Central

Negishi, Michiro; Abildgaard, Mark; Laufer, Ilan; Nixon, Terry; Constable, Robert Todd

2008-01-01

Simultaneous EEG-fMRI (Electroencephalography-functional Magnetic Resonance Imaging) recording provides a means for acquiring high temporal resolution electrophysiological data and high spatial resolution metabolic data of the brain in the same experimental runs. Carbon wire electrodes (not metallic EEG electrodes with carbon wire leads) are suitable for simultaneous EEG-fMRI recording, because they cause less RF (radio-frequency) heating and susceptibility artifacts than metallic electrodes. These characteristics are especially desirable for recording the EEG in high field MRI scanners. Carbon wire electrodes are also comfortable to wear during long recording sessions. However, carbon electrodes have high electrode-electrolyte potentials compared to widely used Ag/AgCl (silver/silver-chloride) electrodes, which may cause slow voltage drifts. This paper introduces a prototype EEG recording system with carbon wire electrodes and a circuit that suppresses the slow voltage drift. The system was tested for the voltage drift, RF heating, susceptibility artifact, and impedance, and was also evaluated in a simultaneous ERP (event-related potential)-fMRI experiment. PMID:18588913

A chemosensor for micro- to nano-molar detection of Ag+ and Hg2+ ions in pure aqueous media and its applications in cell imaging.

PubMed

Nandre, Jitendra P; Patil, Samadhan R; Sahoo, Suban K; Pradeep, Chullikkattil P; Churakov, Andrei; Yu, Fabiao; Chen, Lingxin; Redshaw, Carl; Patil, Ashok A; Patil, Umesh D

2017-10-24

The pyridine substituted thiourea derivative PTB-1 was synthesized and characterized by spectroscopic techniques as well as by single crystal X-ray crystallography. The metal ion sensing ability of PTB-1 was explored by various experimental (naked-eye, UV-Vis, fluorescence, mass spectrometry and 1 H NMR spectroscopy) and theoretical (B3LYP/6-31G**/LANL2DZ) methods. PTB-1 exhibited a highly selective naked-eye detectable color change from colorless to dark brown and UV-Vis spectral changes for the detection of Ag + with a detection limit of 3.67 μM in aqueous medium. The detection of Ag + ions was achieved by test paper strip and supported silica methods. In contrast, PTB-1 exhibited a 23-fold enhanced emission at 420 nm in the presence of Hg 2+ ions with a nano-molar detection limit of 0.69 nM. Finally, the sensor PTB-1 was applied successfully for the intracellular detection of Hg 2+ ions in a HepG2 liver cell line, which was monitored by the use of confocal imaging techniques.

Laser Annealing on the Surface Treatment of Thin Super Elastic NiTi Wire

NASA Astrophysics Data System (ADS)

Samal, S.; Heller, L.; Brajer, J.; Tyc, O.; Kadrevek, L.; Sittner, P.

2018-05-01

Here the aim of this research is annealing the surface of NiTi wire for shape memory alloy, super-elastic wire by solid state laser beam. The laser surface treatment was carried out on the NiTi wire locally with fast, selective, surface heat treatment that enables precisely tune the localized material properties without any precipitation. Both as drawn (hard) and straight annealing NiTi wire were considered for laser annealing with input power 3 W, with precisely focusing the laser beam height 14.3 % of the Z-axis with a spot size of 1 mm. However, straight annealing wire is more interest due to its low temperature shape setting behavior and used by companies for stent materials. The variable parameter such as speed of the laser scanning and tensile stress on the NiTi wire were optimized to observe the effect of laser response on the sample. Superelastic, straight annealed NiTi wires (d: 0.10 mm) were held prestrained at the end of the superelastic plateau (ε: 5 ∼6.5 %) above the superelastic region by a tensile machine ( Mitter: miniature testing rig) at room temperature (RT). Simultaneously, the hardness of the wires along the cross-section was performed by nano-indentation (NI) method. The hardness of the NiTi wire corresponds to phase changes were correlated with NI test. The laser induced NiTi wire shows better fatigue performance with improved 6500 cycles.

Autoclave mediated one-pot-one-minute synthesis of AgNPs and Au-Ag nanocomposite from Melia azedarach bark extract with antimicrobial activity against food pathogens.

PubMed

Pani, Alok; Lee, Joong Hee; Yun, Soon-Ii

2016-01-01

The increasing use of nanoparticles and nanocomposite in pharmaceutical and processed food industry have increased the demand for nontoxic and inert metallic nanostructures. Chemical and physical method of synthesis of nanostructures is most popular in industrial production, despite the fact that these methods are labor intensive and/or generate toxic effluents. There has been an increasing demand for rapid, ecofriendly and relatively cheaper synthesis of nanostructures. Here, we propose a strategy, for one-minute green synthesis of AgNPs and a one-pot one-minute green synthesis of Au-Ag nanocomposite, using Melia azedarach bark aqueous extract as reducing agent. The hydrothermal mechanism of the autoclave technology has been successfully used in this study to accelerate the nucleation and growth of nano-crystals. The study also presents high antimicrobial potential of the synthesized nano solutions against common food and water born pathogens. The multistep characterization and analysis of the synthesized nanomaterial samples, using UV-visible spectroscopy, ICP-MS, FT-IR, EDX, XRD, HR-TEM and FE-SEM, also reveal the reaction dynamics of AgNO3, AuCl3 and plant extract in synthesis of the nanoparticles and nanocomposite. The antimicrobial effectiveness of the synthesized Au-Ag nanocomposite, with high gold to silver ratio, reduces the dependency on the AgNPs, which is considered to be environmentally more toxic than the gold counterpart. We hope that this new strategy will change the present course of green synthesis. The rapidity of synthesis will also help in industrial scale green production of nanostructures using Melia azedarach.

Cu, Ag, Au: Electrical Resistivity Along their Melting Boundaries

NASA Astrophysics Data System (ADS)

Secco, R.; Littleton, J. A. H.; Berrada, M.; Ezenwa, I.; Yong, W.

2017-12-01

Electrical resistivity of Cu, Ag and Au was measured at pressures up to 5 GPa and temperatures up to 300 K above melting in a 1000-ton cubic anvil press. Two W/Re thermocouples placed at opposite ends of the wire sample served as T probes as well as 4-wire resistance electrodes in a switched circuit. A polarity switch was also used to remove any bias associated with current flow and voltage measurement using thermocouple legs. Examination of the composition of recovered and sectioned samples was carried out using electron microprobe analyses. Melting temperatures at high pressures were determined from the large jump in resistivity on heating at constant pressure and these agree well with previous experimental and theoretical phase diagram studies. With increasing P and T, electrical resistivity behavior in these noble metals is consistent with 1atm data. The resistivity values at the melting temperature of Cu and Ag decrease with increasing high pressure and Au seems to behave similarly. The results are compared to prediction by Stacey and Anderson (PEPI, 2001).

Disulphide linkage: To get cleaved or not? Bulk and nano copper based SERS of cystine

NASA Astrophysics Data System (ADS)

P. J., Arathi; Seemesh, Bhaskar; Rajendra Kumar Reddy, G.; Suresh Kumar, P.; Ramanathan, V.

2018-05-01

Different nano-structures of noble metals have been the conventional substrates for carrying out Surface Enhanced Raman Spectroscopy (SERS). In this paper we examine electrodeposited copper (Cu) nano-structures on pencil graphite as novel substrate to carry out SERS measurements by considering L-cystine (Cys-Cys) (dimer of the amino acid cysteine) as the probe. The formation of monolayer of the probe molecule on the substrates was confirmed using cyclic voltammetric measurements. Mode of adsorption of Cys-Cys was observed to be different on bulk Cu (taken in the wire form) and nano-structured Cu on pencil graphite. Whereas in the former the disulphide bond of Cys-Cys remained intact, it got cleaved when Cys-Cys was adsorbed on electrodeposited copper indicating the activated nature of the nano-structure compared to bulk copper. Csbnd S stretching mode of vibration underwent blue shift in Cys-Cys adsorbed on Cu on pencil graphite vis-à-vis Cys-Cys adsorbed on Cu wire. Further evidence on the cleavage of the Csbnd S bond on an activated substrate was obtained by considering a bimetallic substrate comprising of silver on copper which was electrodeposited on pencil graphite. Our studies have demonstrated that nano-copper surface is an excellent substrate for SERS giving 200 μM as lower detection limit for Cys-Cys.

Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

2015-11-01

The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

Improved galvanic replacement growth of Ag microstructures on Cu micro-grid for enhanced SERS detection of organic molecules.

PubMed

Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

2016-04-01

Galvanic growth of Ag nano/micro-structures on Cu micro-grid was systematically studied for surface-enhanced Raman scattering (SERS) applications. Detailed characterizations via FE-SEM and HR-TEM showed that processing parameters, (reaction time, Ag(+) concentration, and PVP addition) all substantially affect thermodynamics/kinetics of the replacement reaction to yield substrates of significantly different microstructures/homogeneities and thus varied SERS performances (sensitivity, enhancement factor, and reproducibility) of the Ag substrates in the detection of R6G analyte. PVP as an additive was shown to notably alter nucleation/growth behaviors of the Ag crystals and promote the deposition of dense and uniform Ag films of nearly monodisperse polyhedrons/nanoplates through suppressing dendrites crystallization. Under optimized synthesis (50mM of Ag(+), 30s of reaction, and 700 wt.% of PVP), Ag substrates exhibiting a high Raman signal enhancement factor of ~1.1 × 10(6) and a low relative standard deviation of ~0.13 in the repeated detection of 10 μM R6G were obtained. The facile deposition and excellent performance reported in this work may allow the Ag microstructures to find wider SERS applications. Moreover, growth mechanisms of the different Ag nano/micro-structures were discussed based on extensive FE-SEM and HR-TEM analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application

NASA Astrophysics Data System (ADS)

Yu, Binyu; Leung, Kar Man; Guo, Qiuquan; Lau, Woon Ming; Yang, Jun

2011-03-01

TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag0 state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm - 2 and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.

Applying Taguchi design and large-scale strategy for mycosynthesis of nano-silver from endophytic Trichoderma harzianum SYA.F4 and its application against phytopathogens

PubMed Central

EL-Moslamy, Shahira H.; Elkady, Marwa F.; Rezk, Ahmed H.; Abdel-Fattah, Yasser R.

2017-01-01

Development of reliable and low-cost requirement for large-scale eco-friendly biogenic synthesis of metallic nanoparticles is an important step for industrial applications of bionanotechnology. In the present study, the mycosynthesis of spherical nano-Ag (12.7 ± 0.8 nm) from extracellular filtrate of local endophytic T. harzianum SYA.F4 strain which have interested mixed bioactive metabolites (alkaloids, flavonoids, tannins, phenols, nitrate reductase (320 nmol/hr/ml), carbohydrate (25 μg/μl) and total protein concentration (2.5 g/l) was reported. Industrial mycosynthesis of nano-Ag can be induced with different characters depending on the fungal cultivation and physical conditions. Taguchi design was applied to improve the physicochemical conditions for nano-Ag production, and the optimum conditions which increased its mass weight 3 times larger than a basal condition were as follows: AgNO3 (0.01 M), diluted reductant (10 v/v, pH 5) and incubated at 30 °C, 200 rpm for 24 hr. Kinetic conversion rates in submerged batch cultivation in 7 L stirred tank bioreactor on using semi-defined cultivation medium was as follows: the maximum biomass production (Xmax) and maximum nano-Ag mass weight (Pmax) calculated (60.5 g/l and 78.4 g/l respectively). The best nano-Ag concentration that formed large inhibition zones was 100 μg/ml which showed against A.alternate (43 mm) followed by Helminthosporium sp. (35 mm), Botrytis sp. (32 mm) and P. arenaria (28 mm). PMID:28349997

Plasmonic excitation-assisted optical and electric enhancement in ultra-thin solar cells: the influence of nano-strip cross section

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

Sabaeian, Mohammad, E-mail: sabaiean@scu.ac.ir; Heydari, Mehdi; Ajamgard, Narges

The effects of Ag nano-strips with triangle, rectangular and trapezoid cross sections on the optical absorption, generation rate, and short-circuit current density of ultra-thin solar cells were investigated. By putting the nano-strips as a grating structure on the top of the solar cells, the waveguide, surface plasmon polariton (SPP), and localized surface plasmon (LSP) modes, which are excited with the assistance of nano-strips, were evaluated in TE and TM polarizations. The results show, firstly, the TM modes are more influential than TE modes in optical and electrical properties enhancement of solar cell, because of plasmonic excitations in TM mode. Secondly,more » the trapezoid nano-strips reveal noticeable impact on the optical absorption, generation rate, and short-circuit current density enhancement than triangle and rectangular ones. In particular, the absorption of long wavelengths which is a challenge in ultra-thin solar cells is significantly improved by using Ag trapezoid nano-strips.« less

Structural and physical properties of antibacterial Ag-doped nano-hydroxyapatite synthesized at 100°C

NASA Astrophysics Data System (ADS)

Ciobanu, Carmen Steluta; Massuyeau, Florian; Constantin, Liliana Violeta; Predoi, Daniela

2011-12-01

Synthesis of nanosized particle of Ag-doped hydroxyapatite with antibacterial properties is in the great interest in the development of new biomedical applications. In this article, we propose a method for synthesized the Ag-doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionized water. Other phase or impurities were not observed. Silver-doped hydroxyapatite nanoparticles (Ag:HAp) were performed by setting the atomic ratio of Ag/[Ag + Ca] at 20% and [Ca + Ag]/P as 1.67. The X-ray diffraction studies demonstrate that powders made by co-precipitation at 100°C exhibit the apatite characteristics with good crystal structure and no new phase or impurity is found. The scanning electron microscopy (SEM) observations suggest that these materials present a little different morphology, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O), and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) analysis. FT-IR and FT-Raman spectroscopies revealed that the presence of the various vibrational modes corresponds to phosphates and hydroxyl groups. The strain of Staphylococcus aureus was used to evaluate the antibacterial activity of the Ca10- x Ag x (PO4)6(OH)2 ( x = 0 and 0.2). In vitro bacterial adhesion study indicated a significant difference between HAp ( x = 0) and Ag:HAp ( x = 0.2). The Ag:Hap nanopowder showed higher inhibition.

Atomic structure of water/Au, Ag, Cu and Pt atomic junctions.

PubMed

Li, Yu; Kaneko, Satoshi; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

2017-02-08

Much progress has been made in understanding the transport properties of atomic-scale conductors. We prepared atomic-scale metal contacts of Cu, Ag, Au and Pt using a mechanically controllable break junction method at 10 K in a cryogenic vacuum. Water molecules were exposed to the metal atomic contacts and the effect of molecular adsorption was investigated by electronic conductance measurements. Statistical analysis of the electronic conductance showed that the water molecule(s) interacted with the surface of the inert Au contact and the reactive Cu ant Pt contacts, where molecular adsorption decreased the electronic conductance. A clear conductance signature of water adsorption was not apparent at the Ag contact. Detailed analysis of the conductance behaviour during a contact-stretching process indicated that metal atomic wires were formed for the Au and Pt contacts. The formation of an Au atomic wire consisting of low coordination number atoms leads to increased reactivity of the inert Au surface towards the adsorption of water.

Junction-Free Electrospun Ag Fiber Electrodes for Flexible Organic Light-Emitting Diodes.

PubMed

Choi, Junhee; Shim, Yong Sub; Park, Cheol Hwee; Hwang, Ha; Kwack, Jin Ho; Lee, Dong Jun; Park, Young Wook; Ju, Byeong-Kwon

2018-02-01

Fabrication of junction-free Ag fiber electrodes for flexible organic light-emitting diodes (OLEDs) is demonstrated. The junction-free Ag fiber electrodes are fabricated by electrospun polymer fibers used as an etch mask and wet etching of Ag thin film. This process facilitates surface roughness control, which is important in transparent electrodes based on metal wires to prevent electrical instability of the OLEDs. The transmittance and resistance of Ag fiber electrodes can be independently adjusted by controlling spinning time and Ag deposition thickness. The Ag fiber electrode shows a transmittance of 91.8% (at 550 nm) at a sheet resistance of 22.3 Ω □ -1 , leading to the highest OLED efficiency. In addition, Ag fiber electrodes exhibit excellent mechanical durability, as shown by measuring the change in resistance under repeatable mechanical bending and various bending radii. The OLEDs with Ag fiber electrodes on a flexible substrate are successfully fabricated, and the OLEDs show an enhancement of EQE (≈19%) compared to commercial indium tin oxide electrodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Conductive Nano-Silver Circuits by Inkjet Printing

NASA Astrophysics Data System (ADS)

Zhu, Dongbin; Wu, Minqiang

2018-06-01

Inkjet technology has become popular in the field of printed electronics due to its superior properties such as simple processes and printable complex patterns. Electrical conductivity of the circuits is one of the key factors in measuring the performance of printed electronics, which requires great material properties and a manufactured process. With excellent conductivity and ductility, silver is an ideal material as the wire connecting components. This review summarizes the progress of conductivity studies on inkjet printed nano-silver lines, including ink composition and nanoparticle morphology, deposition of nano-silver lines with uniform and high aspect ratios, sintering mechanisms and alternative methods of thermal sintering. Finally, the research direction on inkjet printed electronics is proposed.

Optical properties of Ag nanoclusters formed by irradiation and annealing of SiO2/SiO2:Ag thin films

NASA Astrophysics Data System (ADS)

Güner, S.; Budak, S.; Gibson, B.; Ila, D.

2014-08-01

We have deposited five periodic SiO2/SiO2 + Ag multi-nano-layered films on fused silica substrates using physical vapor deposition technique. The co-deposited SiO2:Ag layers were 2.7-5 nm and SiO2 buffer layers were 1-15 nm thick. Total thickness was between 30 and 105 nm. Different concentrations of Ag, ranging from 1.5 to 50 molecular% with respect to SiO2 were deposited to determine relevant rates of nanocluster formation and occurrence of interaction between nanoclusters. Using interferometry as well as in situ thickness monitoring, we measured the thickness of the layers. The concentration of Ag in SiO2 was measured with Rutherford Backscattering Spectrometry (RBS). To nucleate Ag nanoclusters, 5 MeV cross plane Si ion bombardments were performed with fluence varying between 5 × 1014 and 1 × 1016 ions/cm2 values. Optical absorption spectra were recorded in the range of 200-900 nm in order to monitor the Ag nanocluster formation in the thin films. Thermal annealing treatment at different temperatures was applied as second method to form varying size of nanoclusters. The physical properties of formed super lattice were criticized for thermoelectric applications.

Performance comparison of polarized white light emitting diodes using wire-grid polarizers with polymeric and glass substrates

NASA Astrophysics Data System (ADS)

Su, Jung-Chieh; Chou, Shih-Chieh

2018-03-01

Polarized white light emitting diodes (WLEDs) packaged with reflective metal wire-grid polarizer of polymeric and glass substrates were investigated. The performance comparison of polymeric wire-grid polarizer film (WGF) and nano wire-grid polarizer (NWGP) with glass substrate was evaluated. The transverse electric field (TE) polarization transmittance of WGF is less than that of NWGP due to its smaller grid parameters. Despite of the higher duty cycle of WGF, the angular-dependent extinction ratio (ER) of the polarized WLEDs (PWLEDs) with WGF is higher than that of with NWGP. Regarding increasing drive currents, the PWLEDs with NWGP had better color stability than that with WGF due to better substrate thermal stability. In summary, linewidth, period and substrate material are the crucial factors for the PWLED packaging using wire grid polarizer.

Structural and physical properties of antibacterial Ag-doped nano-hydroxyapatite synthesized at 100°C

PubMed Central

2011-01-01

Synthesis of nanosized particle of Ag-doped hydroxyapatite with antibacterial properties is in the great interest in the development of new biomedical applications. In this article, we propose a method for synthesized the Ag-doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionized water. Other phase or impurities were not observed. Silver-doped hydroxyapatite nanoparticles (Ag:HAp) were performed by setting the atomic ratio of Ag/[Ag + Ca] at 20% and [Ca + Ag]/P as 1.67. The X-ray diffraction studies demonstrate that powders made by co-precipitation at 100°C exhibit the apatite characteristics with good crystal structure and no new phase or impurity is found. The scanning electron microscopy (SEM) observations suggest that these materials present a little different morphology, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O), and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) analysis. FT-IR and FT-Raman spectroscopies revealed that the presence of the various vibrational modes corresponds to phosphates and hydroxyl groups. The strain of Staphylococcus aureus was used to evaluate the antibacterial activity of the Ca10-xAgx(PO4)6(OH)2 (x = 0 and 0.2). In vitro bacterial adhesion study indicated a significant difference between HAp (x = 0) and Ag:HAp (x = 0.2). The Ag:Hap nanopowder showed higher inhibition. PMID:22136671

Development of a Cryostat to Characterize Nano-scale Superconducting Quantum Interference Devices

NASA Astrophysics Data System (ADS)

Longo, Mathew; Matheny, Matthew; Knudsen, Jasmine

2016-03-01

We have designed and constructed a low-noise vacuum cryostat to be used for the characterization of nano-scale superconducting quantum interference devices (SQUIDs). Such devices are very sensitive to magnetic fields and can measure changes in flux on the order of a single electron magnetic moment. As a part of the design process, we calculated the separation required between the cryogenic preamplifier and superconducting magnet, including a high-permeability magnetic shield, using a finite-element model of the apparatus. The cryostat comprises a vacuum cross at room temperature for filtered DC and shielded RF electrical connections, a thin-wall stainless steel support tube, a taper-sealed cryogenic vacuum can, and internal mechanical support and wiring for the nanoSQUID. The Dewar is modified with a room-temperature flange with a sliding seal for the cryostat. The flange supports the superconducting 3 Tesla magnet and thermometry wiring. Upon completion of the cryostat fabrication and Dewar modifications, operation of the nanoSQUIDs as transported from our collaborator's laboratory in Israel will be confirmed, as the lead forming the SQUID is sensitive to oxidation and the SQUIDs must be shipped in a vacuum container. After operation of the nanoSQUIDs is confirmed, the primary work of characterizing their high-speed properties will begin. This will include looking at the measurement of relaxation oscillations at high bandwidth in comparison to the theoretical predictions of the current model.

Production of Oxidation-Resistant Cu-Based Nanoparticles by Wire Explosion

PubMed Central

Kawamura, Go; Alvarez, Samuel; Stewart, Ian E.; Catenacci, Matthew; Chen, Zuofeng; Ha, Yoon-Cheol

2015-01-01

The low performance or high cost of commercially available conductive inks limits the advancement of printed electronics. This article studies the explosion of metal wires in aqueous solutions as a simple, low-cost, and environmentally friendly method to prepare metallic nanoparticles consisting of Cu and Cu alloys for use in affordable, highly conductive inks. Addition of 0.2 M ascorbic acid to an aqueous explosion medium prevented the formation of Cu2O shells around Cu nanoparticles, and allowed for the printing of conductive lines directly from these nanoparticles with no post-treatment. Cu alloy nanoparticles were generated from metal wires that were alloyed as purchased, or from two wires of different metals that were twisted together. Cu nanoparticles alloyed with 1% Sn, 5% Ag, 5% Ni and 30% Ni had electrical conductivities similar to Cu but unlike Cu, remained conductive after 24 hrs at 85 °C and 85% RH. PMID:26669447

The Effect of Cu:Ag Atomic Ratio on the Properties of Sputtered Cu–Ag Alloy Thin Films

PubMed Central

Hsieh, Janghsing; Hung, Shunyang

2016-01-01

Cu–Ag thin films with various atomic ratios were prepared using a co-sputtering technique, followed by rapid thermal annealing at various temperatures. The films’ structural, mechanical, and electrical properties were then characterized using X-ray diffractometry (XRD), atomic force microscopy (AFM), FESEM, nano-indentation, and TEM as functions of compositions and annealing conditions. In the as-deposited condition, the structure of these films transformed from a one-phase to a dual-phase state, and the resistivity shows a twin-peak pattern, which can be explained in part by Nordheim’s Rule and the miscibility gap of Cu–Ag alloy. After being annealed, the films’ resistivity followed the mixture rule in general, mainly due to the formation of a dual-phase structure containing Ag-rich and Cu-rich phases. The surface morphology and structure also varied as compositions and annealing conditions changed. The recrystallization of these films varied depending on Ag–Cu compositions. The annealed films composed of 40 at % to 60 at % Cu had higher hardness and lower roughness than those with other compositions. Particularly, the Cu50Ag50 film had the highest hardness after being annealed. From the dissolution testing, it was found that the Cu-ion concentration was about 40 times higher than that of Ag. The galvanic effect and over-saturated state could be the cause of the accelerated Cu dissolution and the reduced dissolution of the Ag. PMID:28774033

The electronic and optical properties of quantum nano-structures

NASA Astrophysics Data System (ADS)

Ham, Heon

In semiconducting quantum nano-structures, the excitonic effects play an important role when we fabricate opto-electronic devices, such as lasers, diodes, detectors, etc. To gain a better understanding of the excitonic effects in quantum nano-structures, we investigated the exciton binding energy, oscillator strength, and linewidth in quantum nano-structures using both the infinite and finite well models. We investigated also the hydrogenic impurity binding energy and the photoionization cross section of the hydrogenic impurity in a spherical quantum dot. In our work, the variational approach is used in all calculations, because the Hamiltonian of the system is not separable, due to the different symmetries of the Coulomb and confining potentials. In the infinite well model of the semiconducting quantum nanostructures, the binding energy of the exciton increases with decreasing width of the potential barriers due to the increase in the effective strength of the Coulomb interaction between the electron and hole. In the finite well model, the exciton binding energy reaches a peak value, and the binding energy decreases with further decrease in the width of the potential barriers. The exciton linewidth in the infinite well model increases with decreasing wire radius, because the scattering rate of the exciton increases with decreasing wire radius. In the finite well model, the exciton linewidth in a cylindrical quantum wire reaches a peak value and the exciton linewidth decreases with further decrease in the wire radius, because the exciton is not well confined at very smaller wire radii. The binding energy of the hydrogenic impurity in a spherical quantum dot has also calculated using both the infinite and the finite well models. The binding energy of the hydrogenic impurity was calculated for on center and off center impurities in the spherical quantum dots. With decreasing radii of the dots, the binding energy of the hydrogenic impurity increases in the infinite

Plasmonic Behavior of Ag/Dielectric Nanowires and the Effect of Geometry

DTIC Science & Technology

2009-07-01

in- cluding random Ga2O3 nanowires, ZnO nanowires, as well as Au lines produced by e-beam lithography. The growth of the Ga2O3 nanowires was achieved...PLASMONIC PROPERTIES As discussed above, we have developed a SERS substrate, consisting of Ga2O3 nanowire core/Ag metal sheath nano- structures, which have...signal. As is evident, the nanowire composites are about two orders of magnitude more sensitive than the Mesophotonics substrate. Since these Ga2O3 /Ag

Nano-Material and Structural Engineering for Thermal Highways

DTIC Science & Technology

2013-06-14

which are covered with a porous anodized aluminum oxide ( AAO ) membrane that is compatible to most if not all semiconductor electronics chips and has... aluminum oxide ( AAO ) templates as hard masks for fabrication of nanomesh thermoelectric structures. Both USPI’s and KPI’s laboratories have accumulated...T. Bigioni, M. Moskovits, and J. M. Xu, “Electrochemical fabrication of CdS nano-wire arrays in porous anodic aluminum oxide templates”, J. Phys

Energy Deposition and Condition of the Metal Core in Exploding Wire Experiments

NASA Astrophysics Data System (ADS)

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W.; McDaniel, D. H.; Waisman, E. M.; Sasorov, P. V.

2002-11-01

Measurements of the Joule energy deposition into exploding wire and its relation with condition of the expanding wire core are presented. Wires of nine different metals with diameters of 10-30 microns, have been exploded by fast 150A/ns and slow 20A/ns pulses, in vacuum and in air. It has been shown by interferometry and light emission that expanding wire core has different conditions. The substances with small atomization enthalpy (Ag, Al, Cu, Au) demonstrate full vaporization of the wire core. The refractory metals (Ti, Pt, Mo, W) demonstrates that core consists from vapor and small and hot microparticles. In this case we observe "firework effect" when large radiation from the wire exceed the energy deposition time in a three order of magnitude. For non-refractory metals radiation dropping fast in 100 ns time scale due to effective adiabatic cooling. It is possible if main part of the metal core was vaporized. The interferometrical investigation of the refraction coefficient of expanding metal core is proof this conclusion. It has been shown that energy deposition before surface breakdown dependent strongly from current rate, surface coatings, environment, wire diameter and radial electric field. The regime of wire explosion in vacuum without shunting plasma shell has been realized for fast exploding mode. In this case we observe anomaly high energy deposition in to the wire core exceeding regular value in almost 20 times. The experimental results for Al wire have been compared with ALEGRA 2D MHD simulations. *Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL8500.

Recyclability assessment of nano-reinforced plastic packaging.

PubMed

Sánchez, C; Hortal, M; Aliaga, C; Devis, A; Cloquell-Ballester, V A

2014-12-01

Packaging is expected to become the leading application for nano-composites by 2020 due to the great advantages on mechanical and active properties achieved with these substances. As novel materials, and although there are some current applications in the market, there is still unknown areas under development. One key issue to be addressed is to know more about the implications of the nano-composite packaging materials once they become waste. The present study evaluates the extrusion process of four nanomaterials (Layered silicate modified nanoclay (Nanoclay1), Calcium Carbonate (CaCO3), Silver (Ag) and Zinc Oxide (ZnO) as part of different virgin polymer matrices of polyethylene (PE), Polypropylene (PP) and Polyethyleneterephtalate (PET). Thus, the following film plastic materials: (PE-Nanoclay1, PE-CaCO3, PP-Ag, PET-ZnO, PET-Ag, PET-Nanoclay1) have been processed considering different recycling scenarios. Results on recyclability show that for PE and PP, in general terms and except for some minor variations in yellowness index, tensile modulus, tensile strength and tear strength (PE with Nanoclay1, PP with Ag), the introduction of nanomaterial in the recycling streams for plastic films does not affect the final recycled plastic material in terms of mechanical properties and material quality compared to conventional recycled plastic. Regarding PET, results show that the increasing addition of nanomaterial into the recycled PET matrix (especially PET-Ag) could influence important properties of the recycled material, due to a slight degradation of the polymer, such as increasing pinholes, degradation fumes and elongation at break. Moreover, it should be noted that colour deviations were visible in most of the samples (PE, PP and PET) in levels higher than 0.3 units (limit perceivable by the human eye). The acceptance of these changes in the properties of recycled PE, PP and PET will depend on the specific applications considered (e.g. packaging applications are more

A study on the correlation between the dewetting temperature of Ag film and SERS intensity.

PubMed

Quan, Jiamin; Zhang, Jie; Qi, Xueqiang; Li, Junying; Wang, Ning; Zhu, Yong

2017-11-07

The thermally dewetted metal nano-islands have been actively investigated as cost-effective SERS-active substrates with a large area, good reproducibility and repeatability via simple fabrication process. However, the correlation between the dewetting temperature of metal film and SERS intensity hasn't been systematically studied. In this work, taking Ag nano-islands (AgNIs) as an example, we reported a strategy to investigate the correlation between the dewetting temperature of metal film and SERS intensity. We described the morphology evolution of AgNIs on the SiO 2 planar substrate in different temperatures and got the quantitative information in surface-limited diffusion process (SLDP) as a function of annealing temperature via classical mean-field nucleation theory. Those functions were further used in the simulation of electromagnetic field to obtain the correlation between the dewetting temperature of Ag film and theoretical analysis. In addition, Raman mapping was done on samples annealed at different temperatures, with R6G as an analyte, to accomplish the analysis of the correlation between the dewetting temperature of Ag film and SERS intensity, which is consistent with the theoretical analysis. For SLDP, we used the morphological characterization of five samples prepared by different annealing temperatures to successfully illustrate the change in SERS intensity with the temperature fluctuation, obtaining a small deviation between the experimental results and theoretic prediction.

Antifungal Effects of Silver Nanoparticles (AgNPs) against Various Plant Pathogenic Fungi.

PubMed

Kim, Sang Woo; Jung, Jin Hee; Lamsal, Kabir; Kim, Yun Seok; Min, Ji Seon; Lee, Youn Su

2012-03-01

This research is concerned with the fungicidal properties of nano-size silver colloidal solution used as an agent for antifungal treatment of various plant pathogens. We used WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R silver nanoparticles (AgNPs) at concentrations of 10, 25, 50, and 100 ppm. Eighteen different plant pathogenic fungi were treated with these AgNPs on potato dextrose agar (PDA), malt extract agar, and corn meal agar plates. We calculated fungal inhibition in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. The results indicated that AgNPs possess antifungal properties against these plant pathogens at various levels. Treatment with WA-CV-WB13R AgNPs resulted in maximum inhibition of most fungi. Results also showed that the most significant inhibition of plant pathogenic fungi was observed on PDA and 100 ppm of AgNPs.

Pressure-assisted melt-filling and optical characterization of Au nano-wires in microstructured fibers.

PubMed

Lee, H W; Schmidt, M A; Russell, R F; Joly, N Y; Tyagi, H K; Uebel, P; Russell, P St J

2011-06-20

We report a novel splicing-based pressure-assisted melt-filling technique for creating metallic nanowires in hollow channels in microstructured silica fibers. Wires with diameters as small as 120 nm (typical aspect ration 50:1) could be realized at a filling pressure of 300 bar. As an example we investigate a conventional single-mode step-index fiber with a parallel gold nanowire (wire diameter 510 nm) running next to the core. Optical transmission spectra show dips at wavelengths where guided surface plasmon modes on the nanowire phase match to the glass core mode. By monitoring the side-scattered light at narrow breaks in the nanowire, the loss could be estimated. Values as low as 0.7 dB/mm were measured at resonance, corresponding to those of an ultra-long-range eigenmode of the glass-core/nanowire system. By thermal treatment the hollow channel could be collapsed controllably, permitting creation of a conical gold nanowire, the optical properties of which could be monitored by side-scattering. The reproducibility of the technique and the high optical quality of the wires suggest applications in fields such as nonlinear plasmonics, near-field scanning optical microscope tips, cylindrical polarizers, optical sensing and telecommunications.

Effective reduction of p-nitrophenol by silver nanoparticle loaded on magnetic Fe3O4/ATO nano-composite

NASA Astrophysics Data System (ADS)

Karki, Hem Prakash; Ojha, Devi Prashad; Joshi, Mahesh Kumar; Kim, Han Joo

2018-03-01

A silver loaded hematite (Fe3O4) and antimony doped tin oxide (ATO) magnetic nano-composite (Ag-Fe3O4/ATO) was successfully synthesized by in situ one pot green and facile hydrothermal process. The formation of nano-composite, its structure, morphology, and stability were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), elemental mapping by high resolution scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR). UV-vis spectroscopy was used to monitor the catalytic reduction of p-nitrophenol (PNP) into p-aminophenol (PAP) in presence of Ag-Fe3O4/ATO nano-composite with excess of sodium borohydride (NaBH4). The pseudo-first order kinetic equation could describe the reduction of p-nitrophenol with excess of NaBH4. For the first time, ATO surface was used for hydrothermal growth of silver and iron oxide magnetic nanoparticles. The in situ growth of these nanoparticles provided an effective bonding of components of the nano-composite over the surface of ATO nanoparticles. This nano-composite exhibited easy synthesis, high stability, cost effective and rapid separation using external magnet. The excellent catalytic and anti-bacterial activity of as-synthesized silver nano-composite makes it potential nano-catalyst for waste water treatment as well as biomedical application.

Development of CMC hydrogels loaded with silver nano-particles for medical applications.

PubMed

Hebeish, Ali; Hashem, M; El-Hady, M M Abd; Sharaf, S

2013-01-30

Innovative CMC-based hydrogels with great potentials for usage in medical area were principally synthesized as per two strategies .The first involved reaction of epichlorohydrin in alkaline medium containing silver nitrate to yield silver nano-particles (AgNPs)-loaded CMC hydrogel. While CMC acted as stabilizing for AgNPs, trisodium citrate was added to the reaction medium to assist CMC in establishing reduction of Ag(+) to AgNPs. The second strategy entailed preparation of CMC hydrogel which assists the in situ preparation of AgNPs under the same conditions. In both strategies, factors affecting the characterization of AgNPs-loaded CMC hydrogels were studied. Analysis and characterization of the so obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, EDX, UV-vis spectrophotometer and TEM. Antimicrobial activity of the hydrogels was examined and mechanisms involved in their synthesis were reported. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nucleation and growth of zinc oxide nanorods directly on metal wire by sonochemical method.

PubMed

Rayathulhan, Ruzaina; Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

2017-03-01

ZnO nanorods were directly grown on four different wires (silver, nickel, copper, and tungsten) using sonochemical method. Zinc nitrate hexahydrate and hexamethylenetetramine (HMT) were used as precursors. Influence of growth parameters such as precursors' concentration and ultrasonic power on the grown nanorods were determined. The results demonstrated that the precursor concentration affected the growth structure and density of the nanorods. The morphology, distribution, and orientation of nanorods changed as the ultrasonic power changed. Nucleation of ZnO nanorods on the wire occurred at lower ultrasonic power and when the power increased, the formation and growth of ZnO nanorods on the wires were initiated. The best morphology, size, distribution, and orientation of the nanorods were observed on the Ag wire. The presence of single crystal nanorod with hexagonal shaped was obtained. This shape indicates that the ZnO nanorods corresponded to the hexagonal wurtzite structure with growth preferential towards the (002) direction. Copyright © 2016 Elsevier B.V. All rights reserved.

Precision wire feeder for small diameter wire

DOEpatents

Brandon, Eldon D.; Hooper, Frederick M.; Reichenbach, Marvin L.

1992-01-01

A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut.

Precision wire feeder for small diameter wire

DOEpatents

Brandon, E.D.; Hooper, F.M.; Reichenbach, M.L.

1992-08-11

A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut. 1 figure.

Oil-in-Water Self-Assembled Synthesis of Ag@AgCl Nano-Particles on Flower-like Bi2O2CO3 with Enhanced Visible-Light-Driven Photocatalytic Activity

PubMed Central

Lin, Shuanglong; Liu, Li; Liang, Yinghua; Cui, Wenquan; Zhang, Zisheng

2016-01-01

In this work, a series of novel flower-like Ag@AgCl/Bi2O2CO3 were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray fluorescence spectrometer (XRF), etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, but exerted a great influence on the photocatalytic activity of Bi2O2CO3 and enhanced the absorption band of pure Bi2O2CO3. The photocatalytic activities of the Ag@AgCl/Bi2O2CO3 samples were determined by photocatalytic degradation of methylene blue (MB) under visible light irradiation. The Ag@AgCl (10 wt %)/Bi2O2CO3 composite showed the highest photocatalytic activity, degrading 97.9% MB after irradiation for 20 min, which is over 1.64 and 3.66 times faster than that of pure Ag@AgCl (calculated based on the equivalent Ag@AgCl content in Ag@AgCl (10 wt %)/Bi2O2CO3) and pure Bi2O2CO3, respectively. Bisphenol A (BPA) was also degraded to further prove the degradation ability of Ag@AgCl/Bi2O2CO3. Photocurrent studies indicated that the recombination of photo-generated electron–hole pairs was decreased effectively due to the formation of heterojunctions between flower-like Bi2O2CO3 and Ag@AgCl nanoparticles. Trapping experiments indicated that O2−, h+ and Cl° acted as the main reactive species for MB degradation in the present photocatalytic system. Furthermore, the cycling experiments revealed the good stability of Ag@AgCl/Bi2O2CO3 composites. Based on the above, a photocatalytic mechanism for the degradation of organic compounds over Ag@AgCl/Bi2O2CO3 was proposed. PMID:28773607

Well-ordered polymer nano-fibers with self-cleaning property by disturbing crystallization process

NASA Astrophysics Data System (ADS)

Yang, Qin; Luo, Zhuangzhu; Tan, Sheng; Luo, Yimin; Wang, Yunjiao; Zhang, Zhaozhu; Liu, Weimin

2014-07-01

Bionic self-cleaning surfaces with well-ordered polymer nano-fibers are firstly fabricated by disturbing crystallization during one-step coating-curing process. Orderly thin (100 nm) and long (5-10 μm) polymer nano-fibers with a certain direction are fabricated by external macroscopic force ( F blow) interference introduced by H2 gas flow, leading to superior superhydrophobicity with a water contact angle (WCA) of 170° and a water sliding angle (WSA) of 0-1°. In contrast, nano-wires and nano-bridges (1-8 μm in length/10-80 nm in width) are generated by "spinning/stretching" under internal microscopic force ( F T) interference due to significant temperature difference in the non-uniform cooling medium. The findings provide a novel theoretical basis for controllable polymer "bionic lotus" surface and will further promote practical application in many engineering fields such as drag-reduction and anti-icing.

[Effect of stability and dissolution of realgar nano-particles using solid dispersion technology].

PubMed

Guo, Teng; Shi, Feng; Yang, Gang; Feng, Nian-Ping

2013-09-01

To improve the stability and dissolution of realgar nano-particles by solid dispersion. Using polyethylene glycol 6000 and poloxamer-188 as carriers, the solid dispersions were prepare by melting method. XRD, microscopic inspection were used to determine the status of realgar nano-particles in solid dispersions. The content and stability test of As(2)0(3) were determined by DDC-Ag method. Hydride generation atomic absorption spectrometry was used to determine the content of Arsenic and investigated the in vitro dissolution behavior of solid dispersions. The results of XRD and microscopic inspection showed that realgar nano-particles in solid dispersions were amorphous. The dissolution amount and rate of Arsenic from realgar nano-particles of all solid dispersions were increased significantly, the reunion of realgar nano-particles and content of As(2)0(3) were reduced for the formation of solid dispersions. The solid dispersion of realgar nano-particles with poloxamer-188 as carriers could obviously improve stability, dissolution and solubility.

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare...

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 77.1802 Section 77.1802... Wires and Trolley Feeder Wires § 77.1802 Insulation of trolley wires, trolley feeder wires and bare...

Approaching the resolution limit of W-C nano-gaps using focused ion beam chemical vapour deposition

NASA Astrophysics Data System (ADS)

Dai, Jun; Chang, Hui; Maeda, Etsuo; Warisawa, Shin'ichi; Kometani, Reo

2018-01-01

Nano-gaps are fundamental building blocks for nanochannels, plasmonic nanostructures and superconducting Josephson junctions. We present a systematic study on the formation mechanism and resolution limit of W-C nano-gaps fabricated using focused-ion-beam chemical vapour deposition (FIB-CVD). First, the deposition size of the nanostructures is evaluated. The size averaged over 100 dots is 32 nm at FWHM. Line and space are also fabricated with the smallest size, having a spacing of only 5 nm at FWHM. Then, a model is developed to study the formation mechanism and provides the design basis for W-C nano-gaps. Both experimental and simulation results reveal that the shrinkage of W-C nano-gaps is accelerated as the Gaussian parts of the nano-wire profiles overlap. A Nano-gap with a length of 5 nm and height difference as high as 42 nm is synthesized. We believe that FIB-CVD opens avenues for novel functional nanodevices that can be potentially used for biosensing, photodetecting, or quantum computing.

Effects of particle size and coating on nanoscale Ag and TiO₂ exposure in zebrafish (Danio rerio) embryos.

PubMed

Osborne, Olivia J; Johnston, Blair D; Moger, Julian; Balousha, Mohammed; Lead, Jamie R; Kudoh, Tetsuhiro; Tyler, Charles R

2013-12-01

Manufactured metal (oxide) nanoparticles are entering the aquatic environment with little understanding on their potential health impacts for exposed organisms. Adopting an integrative approach, we investigated effects of particle size and coating on biological responses for two of the most commonly used metal (oxide) nanoscale particles, silver (Ag) and titanium dioxide (TiO₂) in zebrafish embryos. Titanium dioxide nanoparticles (nominally, 4 nm, 10 nm, 30 nm and 134 nm) had little or no toxicity on the endpoints measured. Ag both in nano form (10 nm and 35 nm) and its larger counterpart (600-1600 nm) induced dose-dependent lethality and morphological defects, occurring predominantly during gastrula stage. Of the silver material tested 10 nm nanoparticles appeared to be the most toxic. Coating Ag nanoparticles with citrate or fulvic acid decreased toxicity significantly. In situ hybridisation analysis identified the yolk syncytial layer (YSL) as a target tissue for Ag-nano toxicity where there was a significant induction of the heavy metal stress response gene, metallothionein 2 (Mt2) at sub-lethal exposures. Coherent Anti-stroke Raman Scattering (CARS) microscopy provided no evidence for silver particles crossing the chorionic membrane in exposed embryos. Collectively, our data suggest that silver ions play a major role in the toxicity of Ag nanoparticles.

Novel durable bio-photocatalyst purifiers, a non-heterogeneous mechanism: accelerated entrapped dye degradation into structural polysiloxane-shield nano-reactors.

PubMed

Dastjerdi, Roya; Montazer, Majid; Shahsavan, Shadi; Böttcher, Horst; Moghadam, M B; Sarsour, Jamal

2013-01-01

This research has designed innovative Ag/TiO(2) polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO(2) were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity. Copyright © 2012 Elsevier B.V. All rights reserved.

Mechanical properties of high-temperature superconducting wires. Ph.D. Thesis - Illinois Inst. of Tech.

NASA Technical Reports Server (NTRS)

Goretta, K. C.; Cluff, J. A.; Joo, J.; Lanagan, M. T.; Singh, J. P.; Vasanthamohan, N.; Xin, Y.; Wong, K. W.

1995-01-01

Bending strength, fracture toughness, and elastic modulus data were acquired for YBa2Cu3O(x), Bi2Sr2CaCu2O(x) (Bi,Pb)2Sr2Ca2Cu3O(x), and Tl2Ba2Ca2Cu3O(x) bars. These data and thermal expansion coefficients strongly suggest that the maximum possible tensile strain without fracture of bulk tapes or wires is approximately equals 0.2%. In Ag-clad conductors, residual stresses will be of limited benefit, but fractures produced by larger strains can be accommodated by shunting current through the Ag.

Synergy between Printex nano-carbons and silver nanoparticles for sensitive estimation of antioxidant activity.

PubMed

Raymundo-Pereira, Paulo A; Campos, Anderson M; Prado, Thiago M; Furini, Leonardo N; Boas, Naiza V; Calegaro, Marcelo L; Machado, Sergio A S

2016-07-05

We report on the synthesis, characterization and applications of a Printex L6 carbon-silver hybrid nanomaterial (PC-Ag), which was obtained using a polyol method. In addition, we also highlight the use of Printex L6 nano-carbon as a much cheaper alternative to the use of carbon nanotubes and graphene. The silver nanoparticles (AgNP) were prepared directly on the surface of the Printex 6L carbon "nanocarbon" material using ethylene glycol as the reducing agent. The hybrid nanomaterial was characterized by High-angle annular dark-field transmission electron microscopy (HAADF-TEM), energy-dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), Raman spectroscopy and cyclic voltammetry. Optimized electrocatalytic activity on glassy carbon electrode was reached for the architecture GC/PC-Ag, the silver nanoparticles with size ranging between 1 and 2 nm were well-distributed throughout the hybrid material. The synergy between PC nano-carbons and AgNPs was verified by detection of gallic acid (GA) at a low applied potential (0.091 V vs. Ag/AgCl). GA detection was performed in a concentration range between 5.0 × 10(-7) and 8.5 × 10(-6) mol L(-1), with a detection limit of 6.63 × 10(-8) mol L(-1) (66.3 nmol L(-1)), which is considerably lower than similar devices. The approach for fabricating the reproducible GC/PC-Ag electrodes is entirely generic and may be explored for other types of (bio)sensors and devices. Copyright © 2016 Elsevier B.V. All rights reserved.

Life cycle assessment of the application of nanoclays in wire coating

NASA Astrophysics Data System (ADS)

Tellaetxe, A.; Blázquez, M.; Arteche, A.; Egizabal, A.; Ermini, V.; Rose, J.; Chaurand, P.; Unzueta, I.

2012-09-01

A life cycle assessment (LCA) is carried out to compare nanoclay-reinforced polymer wire coatings with conventional ones. While the conventional wire coatings contain standard halogen free retardants, in reinforced coatings, montmorillonite (nanoclay) is incorporated into electric cable linings as a rheological agent for an increased resistance to fire. In addition, a reduced load of standard halogen free retardants is obtained. The synergistic effect of the montmorillonite on traditional flame retardant additives (by the formation of a three-dimensional char network) can lead to a revolution in wire production. The application of nanoclays contributes also to anti-dripping effect and flexibility increase [1]. Some producers have already started commercializing wire with nanotechnology-based coating; in the short term the use of nanoclay in wire coating production will probably reach a significant market share replacing traditional formulations. The main aim of this study is to compare the environmental impacts along the life cycle of a traditional wire coating (mineral flame retardants like ATH or MDH in a polymer matrix) with the nanoclay-reinforced wire coating, where the montmorillonite replaces a low percentage of the mineral flame retardant. The system boundaries of the study include the following unit processes: nanoclay production, thermoplastic material and mineral flame retardants production, cable coating manufacturing by extrusion and different end of life scenarios (recycling, incineration and landfill disposal). Whereas nanoreinforced composites have shown and increased fire retardance, the addition of nanomaterials seems to have no significant relevance in the environmental assessment. However, the lack of nano-specific characterization factors for nanomaterials and emission rates associated to the different life cycle stages -mainly in the extrusion and use phase, where accidental combustions can take place- still remains a challenge for realistic

Scalable synthesis of nano-silicon from beach sand for long cycle life Li-ion batteries.

PubMed

Favors, Zachary; Wang, Wei; Bay, Hamed Hosseini; Mutlu, Zafer; Ahmed, Kazi; Liu, Chueh; Ozkan, Mihrimah; Ozkan, Cengiz S

2014-07-08

Herein, porous nano-silicon has been synthesized via a highly scalable heat scavenger-assisted magnesiothermic reduction of beach sand. This environmentally benign, highly abundant, and low cost SiO₂ source allows for production of nano-silicon at the industry level with excellent electrochemical performance as an anode material for Li-ion batteries. The addition of NaCl, as an effective heat scavenger for the highly exothermic magnesium reduction process, promotes the formation of an interconnected 3D network of nano-silicon with a thickness of 8-10 nm. Carbon coated nano-silicon electrodes achieve remarkable electrochemical performance with a capacity of 1024 mAhg(-1) at 2 Ag(-1) after 1000 cycles.

Control of exposure to hexavalent chromium concentration in shielded metal arc welding fumes by nano-coating of electrodes.

PubMed

Sivapirakasam, S P; Mohan, Sreejith; Santhosh Kumar, M C; Thomas Paul, Ashley; Surianarayanan, M

2017-04-01

Background Cr(VI) is a suspected human carcinogen formed as a by-product of stainless steel welding. Nano-alumina and nano-titania coating of electrodes reduced the welding fume levels. Objective To investigate the effect of nano-coating of welding electrodes on Cr(VI) formation rate (Cr(VI) FR) from a shielded metal arc welding process. Methods The core welding wires were coated with nano-alumina and nano-titania using the sol-gel dip coating technique. Bead-on plate welds were deposited on SS 316 LN plates kept inside a fume test chamber. Cr(VI) analysis was done using an atomic absorption spectrometer (AAS). Results A reduction of 40% and 76%, respectively, in the Cr(VI) FR was observed from nano-alumina and nano-titania coated electrodes. Increase in the fume level decreased the Cr(VI) FR. Discussion Increase in fume levels blocked the UV radiation responsible for the formation of ozone thereby preventing the formation of Cr(VI).

Very-high thermal and electrical conductivity in overpressure-processed Bi2Sr2CaCu2O8+x wires

NASA Astrophysics Data System (ADS)

Bonura, M.; Avitabile, F.; Barth, C.; Jiang, J.; Larbalestier, D.; Fête, A.; Leo, A.; Bottura, L.; Senatore, C.

2018-05-01

The residual-resistivity ratio (RRR) of the normal-metal matrix is a key parameter for the electrical and thermal stability of technical superconductors. In Bi2Sr2CaCu2 {{{O}}}8+x (Bi-2212) round wires, the precursor powders are embedded in a Ag matrix without any diffusion barrier, and elemental diffusion from the superconducting filaments into the Ag might be expected to contaminate the matrix during the melt processing required for high critical current density development. This work shows that the overpressure processing, which is adopted to enhance the critical current performance, improves the thermal and electrical conductivities of the conductor, too. In the case of wires reacted with a standard processing performed in 1 bar O2, the RRR of the Ag matrix is about 90, in spite of the simple conductor design that does not include diffusion barriers. Increasing the total reaction pressure to 100 bar improves the RRR to about 200. The differences in RRR reflect on the thermal conductivity of the whole conductor, which has been investigated in magnetic fields up to 19 T.

A review on preparation of silver nano-particles

NASA Astrophysics Data System (ADS)

Haider, Adawiya J.; Haider, Mohammad J.; Mehde, Mohammad S.

2018-05-01

The term "nano particle" (NP) refers to particle diameter in nanometers in size. Nanoparticles contain a small number of constituent atoms or molecules that differ from the properties inherent in their bulk counterparts, found in various forms such as spherical, triangular, cubic, pentagonal, rod-shaped, shells, elliptical and so on. In this chapter, it has been presented the theoretical concepts of the preparation of AgNPS as powders and collide nanoparticles, techniques of preparation with their characterization (morphology, sign charge and potential value, particle distribution ….etc.). Also, included unique properties of AgNPS that are different from those of their bulk materials like: High surface area to volume ratio effects Quantization of electronic and vibration properties.

Antibacterial properties of nano-silver coated PEEK prepared through magnetron sputtering.

PubMed

Liu, Xiuju; Gan, Kang; Liu, Hong; Song, Xiaoqing; Chen, Tianjie; Liu, Chenchen

2017-09-01

We aimed to investigate the cytotoxicity and antibacterial properties of nano-silver-coated polyetheretherketone (PEEK) produced through magnetron sputtering and provide a theoretical basis for its use in clinical applications. The surfaces of PEEKs were coated with nano-silver at varying thicknesses (3, 6, 9, and 12nm) through magnetron sputtering technology. The resulting coated PEEK samples were classified into the following groups according to the thickness of the nano-silver coating: PEEK-3 (3nm), PEEK-6 (6nm), PEEK-9 (9nm), PEEK-12 (12nm), and PEEK control group. The surface microstructure and composition of each sample were observed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive spectrum (EDS) analysis. The water contact angle of each sample was then measured by contact angle meters. A cell counting kit (CCK-8) was used to analyze the cytotoxicity of the mouse fibroblast cells (L929) in the coated groups (n=5) and group test samples (n=6), negative control (polyethylene, PE) (n=6), and positive control group (phenol) (n=6). The antibacterial properties of the samples were tested by co-culturing Streptococcus mutans and Straphylococcus aureus. The bacteria that adhered to the surface of samples were observed by SEM. The antibacterial adhesion ability of each sample was then evaluated. SEM and AFM analysis results showed that the surfaces of control group samples were smooth but compact. Homogeneous silver nano-particles (AgNPs) and nano-silver coating were uniformly distributed on the surface of the coated group samples. Compared with the control samples, the nano-silver coated samples had a significant increase in surface roughness (P<0.05) as the thickness of their nano-silver coating increased. EDS analysis showed that not only C and O but also Ag were present on the surface of the coated samples. Moreover, the water contact angle of modified samples significantly increased after nano-silver coating modification

Molecular Spintronics: Theory of Spin-Dependent Electron Transport in Fe/BDT/Fe Molecular Wire Systems

NASA Astrophysics Data System (ADS)

Dalgleish, Hugh; Kirczenow, George

2004-03-01

Metal/Molecule/Metal junction systems forming molecular wires are currently the focus of intense study. Recently, spin-dependent electron transport in molecular wires with magnetic Ni electrodes has been studied theoretically, and spin-valve effects have been predicted.* Here we explore theoretically another magnetic molecular wire system, namely, ferromagnetic Fe nano-contacts bridged with 1,4-benzene-dithiolate (BDT). We estimate the essential structural and electronic parameters for this system based on ab initio density functional calculations (DFT) for some simple model systems involving thiol groups and Fe clusters as well as semi-empirical considerations and the known electronic structure of bulk Fe. We then use Lippmann-Schwinger and Green's function techniques together with the Landauer formalism to study spin-dependent transport. *E. G. Emberly and G. Kirczenow, Chem. Phys. 281, 311 (2002); R. Pati, L. Senapati, P.M. Ajayan and S.K. Nayak, Phys. Rev. B68, 100407 (2003).

NanoE-Tox: New and in-depth database concerning ecotoxicity of nanomaterials.

PubMed

Juganson, Katre; Ivask, Angela; Blinova, Irina; Mortimer, Monika; Kahru, Anne

2015-01-01

The increasing production and use of engineered nanomaterials (ENMs) inevitably results in their higher concentrations in the environment. This may lead to undesirable environmental effects and thus warrants risk assessment. The ecotoxicity testing of a wide variety of ENMs rapidly evolving in the market is costly but also ethically questionable when bioassays with vertebrates are conducted. Therefore, alternative methods, e.g., models for predicting toxicity mechanisms of ENMs based on their physico-chemical properties (e.g., quantitative (nano)structure-activity relationships, QSARs/QNARs), should be developed. While the development of such models relies on good-quality experimental toxicity data, most of the available data in the literature even for the same test species are highly variable. In order to map and analyse the state of the art of the existing nanoecotoxicological information suitable for QNARs, we created a database NanoE-Tox that is available as Supporting Information File 1. The database is based on existing literature on ecotoxicology of eight ENMs with different chemical composition: carbon nanotubes (CNTs), fullerenes, silver (Ag), titanium dioxide (TiO2), zinc oxide (ZnO), cerium dioxide (CeO2), copper oxide (CuO), and iron oxide (FeO x ; Fe2O3, Fe3O4). Altogether, NanoE-Tox database consolidates data from 224 articles and lists altogether 1,518 toxicity values (EC50/LC50/NOEC) with corresponding test conditions and physico-chemical parameters of the ENMs as well as reported toxicity mechanisms and uptake of ENMs in the organisms. 35% of the data in NanoE-Tox concerns ecotoxicity of Ag NPs, followed by TiO2 (22%), CeO2 (13%), and ZnO (10%). Most of the data originates from studies with crustaceans (26%), bacteria (17%), fish (13%), and algae (11%). Based on the median toxicity values of the most sensitive organism (data derived from three or more articles) the toxicity order was as follows: Ag > ZnO > CuO > CeO2 > CNTs > TiO2 > FeO x . We

Well-ordered polymer nano-fibers with self-cleaning property by disturbing crystallization process.

PubMed

Yang, Qin; Luo, Zhuangzhu; Tan, Sheng; Luo, Yimin; Wang, Yunjiao; Zhang, Zhaozhu; Liu, Weimin

2014-01-01

Bionic self-cleaning surfaces with well-ordered polymer nano-fibers are firstly fabricated by disturbing crystallization during one-step coating-curing process. Orderly thin (100 nm) and long (5-10 μm) polymer nano-fibers with a certain direction are fabricated by external macroscopic force (F blow) interference introduced by H2 gas flow, leading to superior superhydrophobicity with a water contact angle (WCA) of 170° and a water sliding angle (WSA) of 0-1°. In contrast, nano-wires and nano-bridges (1-8 μm in length/10-80 nm in width) are generated by "spinning/stretching" under internal microscopic force (F T) interference due to significant temperature difference in the non-uniform cooling medium. The findings provide a novel theoretical basis for controllable polymer "bionic lotus" surface and will further promote practical application in many engineering fields such as drag-reduction and anti-icing.

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Trolley Wires and Trolley Feeder Wires § 75.1003...

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires. 75.1003 Section 75.1003... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Trolley Wires and Trolley Feeder Wires § 75.1003...

Mimetic Ag nanoparticle/Zn-based MOF nanocomposite (AgNPs@ZnMOF) capped with molecularly imprinted polymer for the selective detection of patulin.

PubMed

Bagheri, Nafiseh; Khataee, Alireza; Habibi, Biuck; Hassanzadeh, Javad

2018-03-01

Here, Ag nanoparticle/flake-like Zn-based MOF nanocomposite (AgNPs@ZnMOF) with great peroxidase-like activity was applied as an efficient support for molecularly imprinted polymer (MIP) and successfully used for selective determination of patulin. AgNPs@ZnMOF was simply synthesized by creating Ag nanoparticles (Ag NPs) inside the nano-pores of flake-like (Zn)MOF. The high surface area of MOF remarkably improved the catalytic activity of Ag NPs which was assessed by fluorometric, colorimetric and electrochemical techniques. Furthermore, it was observed that patulin could strangely reduce the catalytic activity of AgNPs@ZnMOF, probably due to its electron capturing features. This outcome was the motivation to design an assay for patulin detection. In order to make a selective interaction with patulin molecules, MIP layer was created on the surface of AgNPs@ZnMOF by co-polymerization reaction of 3-aminopropyl triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) monomers wherein patulin was applied as template agent. Combination between the selective identifying feature of MIP and outstanding peroxidase-like activity of novel AgNPs@ZnMOF nanocomposite as well as the sensitive fluorescence detection system was led to the design of a reliable probe for patulin. The prepared MIP-capped AgNPs@ZnMOF catalyzed the H 2 O 2 -terephthalic acid reaction which produced a high florescent product. In the presence of patulin, the fluorescence intensity was decreased proportional to its concentration in the range of 0.1-10µmolL -1 with a detection limit of 0.06µmolL -1 . The proposed method was able to selectively measure patulin in a complex media without significant interfering effects from analogue compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal conductivity enhancement of nano-silver particles dispersed ethylene glycol based nanofluids

NASA Astrophysics Data System (ADS)

Khamliche, Touria; Khamlich, Saleh; Doyle, Terry B.; Makinde, Daniel; Maaza, Malik

2018-03-01

This contribution reports on the thermal conductivity enhancement of nano-silver particles (nAgPs) based nanofluids with various nAgPs’ shapes in view of their potential application in concentrated solar power systems. More accurately, the thermal conductivity behaviour of suspensions of nAgPs dispersed ethylene glycol (nAgPs:EG), prepared by a simple and cost effective chemical synthesis method, is compared with a theoretical prediction. The effect of aging time on the shape of the dispersed nAgPs was clearly observed by the structural, optical and morphological analysis. Spherically shaped and Ag nanowires (AgNWs) with high yields were observed when the nAgPs was aged for 1 and 5 h, respectively. The observed AgNWs showed high aspect ratio (≥200) when EG and polyvinylpyrrolidone (PVP) were used as reductant and structure-directing agents. The thermal conductivity measurements on nAgPs:EG nanofuids with different volume fractions of nAgPs were conducted in a temperature range 25 < T < 50 °C using a guarded hot plate (GHP) method. The thermal conductivity manifested a generally monotonic increase with temperature and an approximately linear relationship with the volume fraction of the nAgPs. Particularly, an enhancement of up to 23% was observed when the nanofluid was aged for 5 h and AgNWs were dominant.

Electromigration and morphological changes in Ag nanostructures

NASA Astrophysics Data System (ADS)

Chatterjee, A.; Bai, T.; Edler, F.; Tegenkamp, C.; Weide-Zaage, K.; Pfnür, H.

2018-02-01

Electromigration (EM) as a structuring tool was investigated in Ag nanowires (width 300 nm, thickness 25 nm) and partly in notched and bow-tie Ag structures on a Si(1 0 0) substrate in ultra-high vacuum using a four-tip scanning tunneling microscope in combination with a scanning electron microscope. From simulations of Ag nanowires we got estimates of temperature profiles, current density profiles, EM and thermal migration (TM) mass flux distributions within the nanowire induced by critical current densities of 108 A cm-2. At room temperature, the electron wind force at these current densities by far dominates over thermal diffusion, and is responsible for formation of voids at the cathode and hillocks at the anode side. For current densities that exceed the critical current densities necessary for EM, a new type of wire-like structure formation was found both at room temperature and at 100 K for notched and bow-tie structures. This suggests that the simultaneous action of EM and TM is structure forming, but with a very small influence of TM at low temperature.

The interaction of Ag with Bi-Pb-Sr-Ca-Cu-O superconductor

NASA Astrophysics Data System (ADS)

Dou, S. X.; Song, K. H.; Liu, H. K.; Sorrell, C. C.; Apperley, M. H.; Gouch, A. J.; Savvides, N.; Hensley, D. W.

1989-10-01

Bi-Pb-Sr-Ca-Cu-O superconductor compounds have been doped with up to 30 wt% Ag, sintered under variable oxygen partial pressure, and characterised in terms of the electrical and crystallographic behaviour. In contrast to previous reports that claim that Ag is the only metal non-poisoning to the superconductivity of Bi-Sr-Ca-Cu-O (BSCCO), it has been found that Ag additions to Bi-Pb-Sr-Ca-Cu-O depress Tc and Jc drastically and cause a large decrease in lattice parameters when samples are treated in air or pure oxygen. However, the lattice parameters, Tc and Jc remain unaffected by Ag additions when samples are heat treated in 0.030-0.067 atm oxygen. It is clear that the Ag reacts with and destabilises the superconducting phase when the samples are treated in air or pure oxygen while, when the samples are heat treated in low oxygen partial pressures, the Ag remains as an isolated inert metal phase that improves the weak links between the grains. This discovery clearly shows the feasibility of Ag-clad superconductor wire. For Ag-clad superconductor tape of 0.1 mm 2 cross sectional area heat treated in air, Jc was measured to be 54 A/cm 2. The same specimen sintered in 0.067 atm oxygen showed that the Jc increased to 2078 A/cm 2.

Effect of size on bulk and surface cohesion energy of metallic nano-particles

NASA Astrophysics Data System (ADS)

Yaghmaee, M. S.; Shokri, B.

2007-04-01

The knowledge of nano-material properties not only helps us to understand the extreme behaviour of small-scale materials better (expected to be different from what we observe from their bulk value) but also helps us to analyse and design new advanced functionalized materials through different nano technologies. Among these fundamental properties, the cohesion (binding) energy mainly describes most behaviours of materials in different environments. In this work, we discuss this fundamental property through a nano-thermodynamical approach using two algorithms, where in the first approach the size dependence of the inner (bulk) cohesion energy is studied, and in the second approach the surface cohesion energy is considered too. The results, which are presented through a computational demonstration (for four different metals: Al, Ga, W and Ag), can be compared with some experimental values for W metallic nano-particles.

Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays

PubMed Central

Liu, Jing; Chen, Chaoyang; Yang, Guangsong; Chen, Yushan; Yang, Cheng-Fu

2017-01-01

The nanosphere lithography (NSL) method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single-layer NSL mask was formed by using self-assembly nano-scale polystyrene (PS) nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single-layer NSL mask. From the observations of scanning electronic microscopy (SEM), we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single-layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e-gun deposition, were used to

Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays.

PubMed

Liu, Jing; Chen, Chaoyang; Yang, Guangsong; Chen, Yushan; Yang, Cheng-Fu

2017-04-03

The nanosphere lithography (NSL) method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single-layer NSL mask was formed by using self-assembly nano-scale polystyrene (PS) nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single-layer NSL mask. From the observations of scanning electronic microscopy (SEM), we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single-layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e-gun deposition, were used to

Basic Wiring.

ERIC Educational Resources Information Center

Kaltwasser, Stan; And Others

This module is the first in a series of three wiring publications; it serves as the foundation for students enrolled in a wiring program. It is a prerequisite to either "Residential Wiring" or "Commercial and Industrial Wiring." The module contains 16 instructional units that cover the following topics: occupational…

A sensitive glucose biosensor based on Ag@C core-shell matrix.

PubMed

Zhou, Xuan; Dai, Xingxin; Li, Jianguo; Long, Yumei; Li, Weifeng; Tu, Yifeng

2015-04-01

Nano-Ag particles were coated with colloidal carbon (Ag@C) to improve its biocompatibility and chemical stability for the preparation of biosensor. The core-shell structure was evidenced by transmission electron microscope (TEM) and the Fourier transfer infrared (FTIR) spectra revealed that the carbon shell is rich of function groups such as -OH and -COOH. The as-prepared Ag@C core-shell structure can offer favorable microenvironment for immobilizing glucose oxidase and the direct electrochemistry process of glucose oxidase (GOD) at Ag@C modified glassy carbon electrode (GCE) was realized. The modified electrode exhibited good response to glucose. Under optimum experimental conditions the biosensor linearly responded to glucose concentration in the range of 0.05-2.5mM, with a detection limit of 0.02mM (S/N=3). The apparent Michaelis-Menten constant (KM(app)) of the biosensor is calculated to be 1.7mM, suggesting high enzymatic activity and affinity toward glucose. In addition, the GOD-Ag@C/Nafion/GCE shows good reproducibility and long-term stability. These results suggested that core-shell structured Ag@C is an ideal matrix for the immobilization of the redox enzymes and further the construction of the sensitive enzyme biosensor. Copyright © 2015 Elsevier B.V. All rights reserved.

Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios

PubMed Central

Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

2016-01-01

Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6–15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products. PMID:27869136

Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios

NASA Astrophysics Data System (ADS)

Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

2016-11-01

Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6-15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products.

Highly luminescent material based on Alq3:Ag nanoparticles.

PubMed

Salah, Numan; Habib, Sami S; Khan, Zishan H

2013-09-01

Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices.

Wire stripper

NASA Technical Reports Server (NTRS)

Economu, M. A. (Inventor)

1978-01-01

An insulation stripper is described which is especially useful for shielded wire, the stripper including a first pair of jaws with blades extending substantially perpendicular to the axis of the wire, and a second pair of jaws with blades extending substantially parallel to the axis of the wire. The first pair of jaws is pressed against the wire so the blades cut into the insulation, and the device is turned to form circumferential cuts in the insulation. Then the second pair of jaws is pressed against the wire so the blades cut into the insulation, and the wire is moved through the device to form longitudinal cuts that permit easy removal of the insulation. Each of the blades is located within the concave face of a V-block, to center the blades on the wire and to limit the depth of blade penetration.

30 CFR 75.701-4 - Grounding wires; capacity of wires.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames...

30 CFR 75.701-4 - Grounding wires; capacity of wires.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames...

High magnetic coercivity of FePt-Ag/MgO granular nanolayers

NASA Astrophysics Data System (ADS)

Roghani, R.; Sebt, S. A.; Khajehnezhad, A.

2018-06-01

L10-FePt ferromagnetic nanoparticles have a hight coercivity of Tesla order. Thus, these nanoparticles, with size of 10 to 15 nm and uniform surface distribution, are suitable in magnetic data storage technology with density of more than 1GB. In order to improve structural and magnetic properties of FePt nanoparticles, some elements and combinations have been added to compound. In this research, we show that due to the presence of the Ag, the phase transition temperature of FePt from fcc to L10-fct phase decreases. The presence of Ag as an additive in FePt-Ag nanocomposite, increases the magnetic coercivity. This nanocomposite, with 10% Ag, was deposited by magnetron sputtering on the MgO heat layer. VSM results of 10 nm nanoparticles show that coercivity has increased up to 1.4 T. XRD and FESEM results confirm that the size of the L10-FePt nanoparticles are 10 nm and their surface distribution are uniform. Ag gradually form nano scale clusters with separate lattice and FePt-Ag nanocomposite appears. The result of this process is emptiness of Ag position in FePt-fcc lattice. So, the mobility of Fe and Pt atoms in this lattice increases and it can be possible for them to move in lower temperature. This mechanism explain the effect of Ag on decreasing the transition temperature to fct-L10 phase, and hight coercivity of FePt nanoparticles.

Development of a novel resin-based dental material with dual biocidal modes and sustained release of Ag+ ions based on photocurable core-shell AgBr/cationic polymer nanocomposites.

PubMed

Cao, Weiwei; Zhang, Yu; Wang, Xi; Chen, Yinyan; Li, Qiang; Xing, Xiaodong; Xiao, Yuhong; Peng, Xuefeng; Ye, Zhiwen

2017-07-01

Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag + ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag + ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag + ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.

Diffusion Mechanisms of Ag atom in ZnO crystal: A First Principles Study

NASA Astrophysics Data System (ADS)

Masoumi, Saeed; Noori, Amirreza; Nadimi, Ebrahim

2017-12-01

Zinc oxide (ZnO) is currently under intensive investigation, as a result of its various applications in micro, nano and optoelectronics. However, a stable and reproducible p-type doping of ZnO is still a main challenging issue. Group IB elements such as Au, Cu and Ag, are promising candidates for p-type doping. Particularly, Ag atoms has been shown to be able to easily diffuse through the crystal structure of ZnO and lead to the p-type doping of the host crystal. However, the current understanding of Ag defects and their mobility in the ZnO crystal is still not fully explored. In this work, we report the results of our first-principles calculations based on density functional theory for Ag defects, particularly the interstitial and substitutional defects in ZnO crystal. Defect formation energies are calculated in different charged states as a function of Fermi energy in order to clarify the p-type behaviour of Ag-doped ZnO. We also investigate the diffusion behaviour and migration paths of Ag in ZnO crystal in the framework of density functional theory applying climbing image (CI) nudged elastic band method (NEB).

High conductive and scalable Ag nanowires flexible transparent electrode by nanowelding with physical methods

NASA Astrophysics Data System (ADS)

He, W. W.; Yan, X. H.; Long, Y. F.; Liang, Y. M.; Pan, C.; Zhao, J. L.; Liu, Q. X.

2017-09-01

Transparent electrodes (TEs) are very important for electronic devices. At present, ITO is gaining the largest market share but will be reduced. Ag nanowires (AgNWs) TEs is acknowledged as one of the most potential alternative to ITO. However, AgNWs TEs still have electrical problems because of the low contact between the AgNWs. In this paper, we report three physics methods to increase the conductivity of AgNWs TEs by nanowelding the contact of nanowires. For heat-resistant materials, 200 °C heat-nanowelding can help to reduce the sheet resistance by 96.7%. For pressure resistant materials, 20MPa pressure-nanowelding can help to increase the conductivity by 98.7%. And the transmittance (>90%) remains constant during the above process. Yet, both of these methods cannot improve the adhesion between nanowires and the substrates. Luckily, tight adhesion can be obtained by overcoating a PEDOT: PSS lalyer on AgNWs film which can reduce the sheet resistance by 87.8%. This means that things are usually not perfect, and they have their own advantages and lay the foundation for the popularization and application of AgNWs TEs. In a word, these three nano-welding methods are all suit for manufacture on a large scale for high conductive AgNWs TEs.

Recyclability assessment of nano-reinforced plastic packaging

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

Sánchez, C., E-mail: csanchez@itene.com; Hortal, M., E-mail: mhortal@itene.com; Aliaga, C., E-mail: caliaga@itene.com

2014-12-15

Highlights: • The study compares the recyclability of polymers with and without nanoparticles. • Visual appearance, material quality and mechanical properties are evaluated. • Minor variations in mechanical properties in R-PE and R-PP with nanoparticles. • Slight degradation of R-PET which affect mechanical properties. • Colour deviations in recycled PE, PP and PET in ranges higher that 0.3 units. - Abstract: Packaging is expected to become the leading application for nano-composites by 2020 due to the great advantages on mechanical and active properties achieved with these substances. As novel materials, and although there are some current applications in the market,more » there is still unknown areas under development. One key issue to be addressed is to know more about the implications of the nano-composite packaging materials once they become waste. The present study evaluates the extrusion process of four nanomaterials (Layered silicate modified nanoclay (Nanoclay1), Calcium Carbonate (CaCO{sub 3}), Silver (Ag) and Zinc Oxide (ZnO) as part of different virgin polymer matrices of polyethylene (PE), Polypropylene (PP) and Polyethyleneterephtalate (PET). Thus, the following film plastic materials: (PE–Nanoclay1, PE–CaCO{sub 3}, PP–Ag, PET–ZnO, PET–Ag, PET–Nanoclay1) have been processed considering different recycling scenarios. Results on recyclability show that for PE and PP, in general terms and except for some minor variations in yellowness index, tensile modulus, tensile strength and tear strength (PE with Nanoclay1, PP with Ag), the introduction of nanomaterial in the recycling streams for plastic films does not affect the final recycled plastic material in terms of mechanical properties and material quality compared to conventional recycled plastic. Regarding PET, results show that the increasing addition of nanomaterial into the recycled PET matrix (especially PET–Ag) could influence important properties of the recycled material

All-optical switching in silicon-on-insulator photonic wire nano-cavities.

PubMed

Belotti, Michele; Galli, Matteo; Gerace, Dario; Andreani, Lucio Claudio; Guizzetti, Giorgio; Md Zain, Ahmad R; Johnson, Nigel P; Sorel, Marc; De La Rue, Richard M

2010-01-18

We report on experimental demonstration of all-optical switching in a silicon-on-insulator photonic wire nanocavity operating at telecom wavelengths. The switching is performed with a control pulse energy as low as approximately 0.1 pJ on a cavity device that presents very high signal transmission, an ultra-high quality-factor, almost diffraction-limited modal volume and a footprint of only 5 microm(2). High-speed modulation of the cavity mode is achieved by means of optical injection of free carriers using a nanosecond pulsed laser. Experimental results are interpreted by means of finite-difference time-domain simulations. The possibility of using this device as a logic gate is also demonstrated.

Effect of nano packaging on preservation quality of Nanjing 9108 rice variety at high temperature and humidity.

PubMed

Wang, Fan; Hu, Qiuhui; Mugambi Mariga, Alfred; Cao, Chongjiang; Yang, Wenjian

2018-01-15

A nano packaging material containing nano Ag, nano TiO 2 , nano attapulgite and SiO 2 was prepared, and its impact on quality of Nanjing 9108 rice at 37°C and 85% relative humidity was studied. Effects of the packaging on ambient gases and chromatic aberration of rice were determined. Moreover, oxidation level, molds growth and flavor of rice were also analyzed. Results showed that nano packaging material had antimicrobial effects and maintained low O 2 and high CO 2 content in the packages. The packages thereby inhibited the growth of molds and the production of fatty acids, restrained the increase of lipase activity, and reduced the oxidation of fats and proteins. As a result, the production of yellow and white-belly rice were inhibited. Furthermore, the color and flavor of rice were maintained. Therefore, the nano-packing material could be applied for preservation of rice to improve preservation quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation of PVA/Co/Ag film and evaluation of its magnetic and microstructural properties

NASA Astrophysics Data System (ADS)

Banerjee, M.; Sachdev, Preeti; Mukherjee, G. S.

2012-05-01

PVA/Co/Ag film has been prepared by sputtering Co followed by Ag in polyvinyl alcohol (PVA) matrix film by IBS technique, so as to get a 9 nm (thick) layer of Co metal nanoparticles followed by a protective 4 nm (thick) layer of Ag nanoparticles. Grazing incidence x-ray diffraction (GIXRD) pattern of the film reveals the formation of nanocrystalline Co with hcp phase. GIXRD pattern also indicates that there is no change in the crystalline structure of PVA even after sputtering of the metallic nanoparticles. The average particle size of Co nanoparticles as evaluated using Scherrer formula is found to be about 2.64 nm. UV visible absorption pattern of the film sample showed SPR peaks of Co and Ag metals in their nano size level embedded in the PVA matrix system. XPS study confirms the metallic nature of Co and Ag nanoparticles; and the depth profiling study reveals that both the metal nanoparticles have been embedded in the PVA matrix system. Surface morphology of such film has been studied using AFM; and the magnetic behaviour of the film studied by using MOKE shows soft ferromagnetic behaviour in this PVA/Co/Ag system.

Wire-bonder-assisted integration of non-bondable SMA wires into MEMS substrates

NASA Astrophysics Data System (ADS)

Fischer, A. C.; Gradin, H.; Schröder, S.; Braun, S.; Stemme, G.; van der Wijngaart, W.; Niklaus, F.

2012-05-01

This paper reports on a novel technique for the integration of NiTi shape memory alloy wires and other non-bondable wire materials into silicon-based microelectromechanical system structures using a standard wire-bonding tool. The efficient placement and alignment functions of the wire-bonding tool are used to mechanically attach the wire to deep-etched silicon anchoring and clamping structures. This approach enables a reliable and accurate integration of wire materials that cannot be wire bonded by traditional means.

Nanostructural Characterization of Low Resistance Joints Using Ag Pastes for GdBa2Cu3O7-x Coated Conductors

NASA Astrophysics Data System (ADS)

Kato, Tomohiro; Machi, Takato; Yokoe, Daisaku; Yoshida, Ryuji; Kato, Takeharu; Izumi, Teruo; Hirayama, Tsukasa; Shiohara, Yuh

2017-07-01

GdBa2Cu3O7-x coated conductors were splice jointed by a face-to-face manner using a paste containing nano-sized Ag particles under a pressure of about 50 MPa at 150 °C for 1 hr. The low electrical resistance of 6 nΩ at the joint was attained. Nanostructural characterizations of the starting Ag paste and the jointed region of the coated conductors were carried out using scanning electron microscopy and transmission electron microscopy. The size of the Ag particles in the starting pastes were confirmed to be a few tens of nanometers in diameter. The size of Ag particles became larger during the jointing process. Both the surfaces of the stabilizing Ag layers were partially bonded by the Ag particles. No oxides or other elements were detected in the region of the bonding parts.

49 CFR 234.241 - Protection of insulated wire; splice in underground wire.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Protection of insulated wire; splice in underground wire. 234.241 Section 234.241 Transportation Other Regulations Relating to Transportation... of insulated wire; splice in underground wire. Insulated wire shall be protected from mechanical...

49 CFR 234.241 - Protection of insulated wire; splice in underground wire.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Protection of insulated wire; splice in underground wire. 234.241 Section 234.241 Transportation Other Regulations Relating to Transportation... of insulated wire; splice in underground wire. Insulated wire shall be protected from mechanical...

Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites

NASA Astrophysics Data System (ADS)

Prakash, Jai; Kumar, Promod; Harris, R. A.; Swart, Chantel; Neethling, J. H.; Janse van Vuuren, A.; Swart, H. C.

2016-09-01

We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

Metering Wheel-Wire Track Wire Boom Deployment Mechanism

NASA Technical Reports Server (NTRS)

Granoff, Mark S.

2014-01-01

The NASA MMS Spin Plane Double Probe (SDP) Deployer utilizes a helical path, rotating Metering Wheel and a spring loaded Wire "Holding" Track to pay out a "fixed end" 57 meter x 1.5 mm diameter Wire Boom stored between concentric storage cylinders. Unlike rotating spool type storage devices, the storage cylinders remain stationary, and the boom wire is uncoiled along the length of the cylinder via the rotation of the Metering Wheel. This uncoiling action avoids the need for slip-ring contacts since the ends of the wire can remain stationary. Conventional fixed electrical connectors (Micro-D type) are used to terminate to operational electronics.

Drug-releasing nano-engineered titanium implants: therapeutic efficacy in 3D cell culture model, controlled release and stability.

PubMed

Gulati, Karan; Kogawa, Masakazu; Prideaux, Matthew; Findlay, David M; Atkins, Gerald J; Losic, Dusan

2016-12-01

There is an ongoing demand for new approaches for treating localized bone pathologies. Here we propose a new strategy for treatment of such conditions, via local delivery of hormones/drugs to the trauma site using drug releasing nano-engineered implants. The proposed implants were prepared in the form of small Ti wires/needles with a nano-engineered oxide layer composed of array of titania nanotubes (TNTs). TNTs implants were inserted into a 3D collagen gel matrix containing human osteoblast-like, and the results confirmed cell migration onto the implants and their attachment and spread. To investigate therapeutic efficacy, TNTs/Ti wires loaded with parathyroid hormone (PTH), an approved anabolic therapeutic for the treatment of severe bone fractures, were inserted into 3D gels containing osteoblast-like cells. Gene expression studies revealed a suppression of SOST (sclerostin) and an increase in RANKL (receptor activator of nuclear factor kappa-B ligand) mRNA expression, confirming the release of PTH from TNTs at concentrations sufficient to alter cell function. The performance of the TNTs wire implants using an example of a drug needed at relatively higher concentrations, the anti-inflammatory drug indomethacin, is also demonstrated. Finally, the mechanical stability of the prepared implants was tested by their insertion into bovine trabecular bone cores ex vivo followed by retrieval, which confirmed the robustness of the TNT structures. This study provides proof of principle for the suitability of the TNT/Ti wire implants for localized bone therapy, which can be customized to cater for specific therapeutic requirements. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced apatite-forming ability and antibacterial activity of porous anodic alumina embedded with CaO-SiO2-Ag2O bioactive materials.

PubMed

Ni, Siyu; Li, Xiaohong; Yang, Pengan; Ni, Shirong; Hong, Feng; Webster, Thomas J

2016-01-01

In this study, to provide porous anodic alumina (PAA) with bioactivity and anti-bacterial properties, sol-gel derived bioactive CaO-SiO2-Ag2O materials were loaded onto and into PAA nano-pores (termed CaO-SiO2-Ag2O/PAA) by a sol-dipping method and subsequent calcination of the gel-glasses. The in vitro apatite-forming ability of the CaO-SiO2-Ag2O/PAA specimens was evaluated by soaking them in simulated body fluid (SBF). The surface microstructure and chemical property before and after soaking in SBF were characterized. Release of ions into the SBF was also measured. In addition, the antibacterial properties of the samples were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results showed that CaO-SiO2-Ag2O bioactive materials were successfully decorated onto and into PAA nano-pores. In vitro SBF experiments revealed that the CaO-SiO2-Ag2O/PAA specimens dramatically enhanced the apatite-forming ability of PAA in SBF and Ca, Si and Ag ions were released from the samples in a sustained and slow manner. Importantly, E. coli and S. aureus were both killed on the CaO-SiO2-Ag2O/PAA (by 100%) samples compared to PAA controls after 3 days of culture. In summary, this study demonstrated that the CaO-SiO2-Ag2O/PAA samples possess good apatite-forming ability and high antibacterial activity causing it to be a promising bioactive coating candidate for implant materials for orthopedic applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Monomer functionalized silica coated with Ag nanoparticles for enhanced SERS hotspots

NASA Astrophysics Data System (ADS)

Newmai, M. Boazbou; Verma, Manoj; Kumar, P. Senthil

2018-05-01

Mesoporous silica (SiO2) spheres are well-known for their excellent chromatographic properties such as the relatively high specific surface, large pore volume, uniform particle size, narrow pore size distribution with favorable pore connectivity; whereas the noble metal Ag nanoparticles have unique size/shape dependant surface plasmon resonance with wide ranging applications. Thus, the desire to synchronize both their properties for specific applications has naturally prompted research in the design and synthesis of core-shell type novel nanoAg@mesoSiO2 nanocomposites, which display potential utility in applications such as photothermal therapy, photocatalysis, molecular sensing, and photovoltaics. In the present work, SiO2 spheres were carefully functionalized with the monomer, N-vinyl pyrrolidone (NVP), which cohesively controls the uniform mass transfer of Ag+ metal ions, thereby enabling its sequential reduction to zerovalent Ag (in the presence of slightly excess NaOH) by electron transfer from nucleophilic attack of the NVP vinyl group by the water molecules even under ambient conditions. Complete metal nanoshell coverage of the silica surface was obtained after multiple Ag deposition cycles, as systematically confirmed from the BET, TEM, optical and FTIR characterization. Our present Ag-coated silica spheres were directly utilized as viable SERS substrates with high sensitivity in contrast with other long chain polymer/surfactant coated silica spheres, owing to the presence of significant number of nanogaps enhanced SERS 'hotspots', which were methodically analyzed utilizing two example analytes, such as crystal violet (CV) and calendula officinalis (CaF).

Effect of deposition of Ag on TiO2 nanoparticles on the photodegradation of Reactive Yellow-17.

PubMed

Rupa, A Valentine; Manikandan, D; Divakar, D; Sivakumar, T

2007-08-25

Nanoparticles of TiO(2) were synthesized by sol-gel technique and the photodeposition of about 1% Ag on TiO(2) particles was carried out. Ag-deposited TiO(2) catalyst was characterised by XRD, TEM and UV-vis spectroscopy. The Ag-TiO(2) catalyst was evaluated for their photocatalytic activity towards the degradation of Reactive Yellow-17 (RY-17) under UV and visible light irradiations. Then the results were compared with synthesized nano-TiO(2) sol and P-25 Degussa and the enhanced degradation was obtained with Ag-deposited TiO(2). This enhanced activity of Ag-TiO(2) may be attributed to the trapping of conduction band electrons. The effect of initial dye concentration, pH and electron acceptors such as H(2)O(2), K(2)S(2)O(8) on the photocatalytic activity were studied and the results obtained were fitted with Langmuir-Hinshelwood model to study the degradation kinetics and discussed in detail.

Metallurgical characterization of M-Wire nickel-titanium shape memory alloy used for endodontic rotary instruments during low-cycle fatigue.

PubMed

Ye, Jia; Gao, Yong

2012-01-01

Rotary instruments made of a new nickel-titanium (NiTi) alloy (M-Wire) have shown improved cyclic fatigue resistance and mechanical properties compared with those made of conventional superelastic NiTi wires. The objective of this study was to characterize microstructural changes of M-Wire throughout the cyclic fatigue process under controlled strain amplitude. The average fatigue life was calculated from 30 M-Wire samples that were subjected to a strain-controlled (≈ 4%) rotating bend fatigue test at room temperature and rotational speed of 300 rpm. Microstructural evolution of M-Wire has been investigated by different metallurgical characterization techniques, including differential scanning calorimetry, Vickers microhardness, and transmission electron microscopy at 4 different stages (as-received state, 30%, 60%, and 90% of average fatigue life). During rotating bend fatigue test, no statistically significant difference (P > .05) was found on austenite finish temperatures between as-received M-Wire and fatigued samples. However, significant differences (P < .05) were observed on Vickers microhardness for samples with 60% and 90% fatigue life compared with as-received and 30% fatigue life. Coincidentally, substantial growth of martensite grains and martensite twins was observed in microstructure under transmission electron microscopy after 60% fatigue life. The results of the present study suggested that endodontic instruments manufactured with M-Wire are expected to have higher strength and wear resistance than similar instruments made of conventional superelastic NiTi wires because of its unique nano-crystalline martensitic microstructure. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Nano-technology and nano-toxicology.

PubMed

Maynard, Robert L

2012-01-01

Rapid developments in nano-technology are likely to confer significant benefits on mankind. But, as with perhaps all new technologies, these benefits are likely to be accompanied by risks, perhaps by new risks. Nano-toxicology is developing in parallel with nano-technology and seeks to define the hazards and risks associated with nano-materials: only when risks have been identified they can be controlled. This article discusses the reasons for concern about the potential effects on health of exposure to nano-materials and relates these to the evidence of the effects on health of the ambient aerosol. A number of hypotheses are proposed and the dangers of adopting unsubstantiated hypotheses are stressed. Nano-toxicology presents many challenges and will need substantial financial support if it is to develop at a rate sufficient to cope with developments in nano-technology.

Nano-technology and nano-toxicology

PubMed Central

Maynard, Robert L.

2012-01-01

Rapid developments in nano-technology are likely to confer significant benefits on mankind. But, as with perhaps all new technologies, these benefits are likely to be accompanied by risks, perhaps by new risks. Nano-toxicology is developing in parallel with nano-technology and seeks to define the hazards and risks associated with nano-materials: only when risks have been identified they can be controlled. This article discusses the reasons for concern about the potential effects on health of exposure to nano-materials and relates these to the evidence of the effects on health of the ambient aerosol. A number of hypotheses are proposed and the dangers of adopting unsubstantiated hypotheses are stressed. Nano-toxicology presents many challenges and will need substantial financial support if it is to develop at a rate sufficient to cope with developments in nano-technology. PMID:22662021

Silver-containing polymer composition used in spacecraft and semiconductor optoelectronics control systems

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

Ivanov, A. A., E-mail: alexchemtsu@rambler.ru; Tuev, V. I., E-mail: tvi-retem@main.tusur.ru

2015-10-27

The copolymer of the vinyl chloride-maleic anhydride and silver nano- and microparticle (70 wt %) composition is offered as a conductive adhesive for fixing various chips on the dielectric substrate. The wiring volume resistivity is up to 3.1×10{sup −8} Ohm×m. The adhesive strength of the silver-containing polymer composition (70% of Ag) applied under a shear on the dielectric substrate is 106 N/mm{sup 2}. Adhesive layers obtained from these substances have a high thermal conductivity up to λ = 199.93 W/m×K that depends on the amount of Ag in the polymer composition.

On the roles of Bi{sub 2}Sr{sub 2}CuO{sub x} intergrowths in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x}/Ag round wires: c-axis transport and magnetic flux pinning

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

Naderi, G., E-mail: gnaderi@ncsu.edu; Schwartz, J.

2014-04-14

Despite progress in the performance of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (Bi2212)/Ag multifilamentary round wires, understanding the impact of microstructural defects on multiple length scales on electrical transport remains a significant challenge. Many recent studies have focused on porosity, but porosity is not the only factor in determining J{sub c}. The primary impurity in partial-melt processed multifilamentary Bi2212 wires is Bi{sub 2}Sr{sub 2}CuO{sub x} (Bi2201), which forms as mesoscopic grains and nanoscopic intergrowths. Previously, we showed the destructive effect of Bi2201 grains on transport. Here, we relate scanning transmission electron microscopy results to the Bi2212 coherence length, anisotropic magnetization behavior,more » and magnetic-field dependent transport to study c-axis transport and the effects of Bi2201 intergrowths on magnetic flux pinning. We show that wide Bi2201 intergrowths are barrier to c-axis transport within Bi2212 grains, whereas narrow (half- and full-cell) Bi2201 intergrowths are not detrimental to c-axis transport and are likely magnetic flux pinning centers. These results have significant impact on the understanding of Bi2212/Bi2201 systems and provide important physical insight towards future improvements in devices based upon wires, film, and junctions.« less

Laser fabrication of Ag-HA nanocomposites on Ti6Al4V implant for enhancing bioactivity and antibacterial capability.

PubMed

Liu, Xiangmei; Man, H C

2017-01-01

For titanium alloy implants, both surface bioactivity and antibacterial infection are the two critical factors in determining the success of clinical implantation of these metallic implants. In the present work, a novel nanocomposite layer of nano-silver-containing hydroxyapatite (Ag-HA) was prepared on the surface of biomedical Ti6Al4V by laser processing. Analysis using SEM, EDS and XRD shows the formation of an Ag-HA layer of about 200μm fusion bonded to the substrate. Mineralization tests in simulated body fluid (SBF) showed that laser fabricated Ag-HA nanocomposite layer favors the deposition of apatite on the surface of the implants. Antibacterial tests confirmed that all Ag-HA nanocomposite layers can kill bacteria while a higher Ag content would lower the cytocompatibility of these coatings. Cell viability decreases when the Ag content reaches 5% in these coatings, due to the larger amount of Ag leached out, as confirmed by ion release evaluation. Our results reveal that laser fabricated Ag-HA nanocomposite coatings containing 2% Ag show both excellent cytocompatibility and antibacterial capability. Copyright © 2016 Elsevier B.V. All rights reserved.

High-efficient catalytic reduction of 4-nitrophenol based on reusable Ag nanoparticles/graphene-loading loofah sponge hybrid.

PubMed

Liu, Y Y; Zhao, Y H; Zhou, Y; Guo, X L; Chen, Z T; Zhang, W J; Zhang, Y; Chen, J; Wang, Z M; Sun, L T; Zhang, T

2018-08-03

Noble metal nanoparticles (NPs) such as Au and Ag have shown many applications in the field of catalysis, sensing etc. due to their excellent photoelectric properties. But agglomeration and a low recovery rate are big problems for their applications. In this research, a novel Ag NPs/graphene (reduced graphene oxide)-loading loofah sponge (Ag NPs/RGO-LS) was synthesized through a one-step reduction method. Where the RGO is used as a nano-support with the high specific surface area and the high conductivity to prevent the agglomeration of Ag NPs and provide a conductive layer. The natural, green, low-cost and high-yield LS is designed as a macro-support to reduce the loss of Ag NPs during recycling. The as-prepared Ag NPs/RGO-LS is stable, uniform, and exhibits high efficiency and reusability in the catalytic reduction of 4-nitrophenol (4-NP) with a high rate constant of 1.893 min -1 as well as an average conversion of 98% in 6 min during five cycles. The results have not only paved the way for the wide application of Ag NPs but also provide a new road for the application of other metal NPs.

Synthesis of supported silver nano-spheres on zinc oxide nanorods for visible light photocatalytic applications

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

Saoud, Khaled; Alsoubaihi, Rola; Bensalah, Nasr

Highlights: • Synthesis of supported Ag NPs on ZnO nanorods using open vessel microwave reactor. • Use of the Ag/ZnO NPs as an efficient visible light photocatalyst. • Complete degradation of methylene blue in 1 h with 0.5 g/L Ag/ZnO NPs. - Abstract: We report the synthesis of silver (Ag) nano-spheres (NS) supported on zinc oxide (ZnO) nanorods through two step mechanism, using open vessel microwave reactor. Direct reduction of ZnO from zinc nitrates was followed by deposition precipitation of the silver on the ZnO nanorods. The supported Ag/ZnO nanoparticles were then characterized by electron microscopy, X-ray diffraction, FTIR, photoluminescencemore » and UV–vis spectroscopy. The visible light photocatalytic activity of Ag/ZnO system was investigated using a test contaminant, methylene blue (MB). Almost complete removal of MB in about 60 min for doses higher than 0.5 g/L of the Ag/ZnO photocatalyst was achieved. This significant improvement in the photocatalytic efficiency of Ag/ZnO photocatalyst under visible light irradiation can be attributed to the presence of Ag nanoparticles on the ZnO nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by surface plasmon resonance effect from Ag nanoparticles.« less

Zinc oxide nano-rods based glucose biosensor devices fabrication

NASA Astrophysics Data System (ADS)

Wahab, H. A.; Salama, A. A.; El Saeid, A. A.; Willander, M.; Nur, O.; Battisha, I. K.

2018-06-01

ZnO is distinguished multifunctional material that has wide applications in biochemical sensor devices. For extracellular measurements, Zinc oxide nano-rods will be deposited on conducting plastic substrate with annealing temperature 150 °C (ZNRP150) and silver wire with annealing temperature 250 °C (ZNRW250), for the extracellular glucose concentration determination with functionalized ZNR-coated biosensors. It was performed in phosphate buffer saline (PBS) over the range from 1 μM to 10 mM and on human blood plasma. The prepared samples crystal structure and surface morphologies were characterized by XRD and field emission scanning electron microscope FESEM respectively.

Concealed wire tracing apparatus

DOEpatents

Kronberg, J.W.

1994-05-31

An apparatus and method that combines a signal generator and a passive signal receiver to detect and record the path of partially or completely concealed electrical wiring without disturbing the concealing surface is disclosed. The signal generator applies a series of electrical pulses to the selected wiring of interest. The applied pulses create a magnetic field about the wiring that can be detected by a coil contained within the signal receiver. An audible output connected to the receiver and driven by the coil reflects the receivers position with respect to the wiring. The receivers audible signal is strongest when the receiver is directly above the wiring and the long axis of the receivers coil is parallel to the wiring. A marking means is mounted on the receiver to mark the location of the wiring as the receiver is directed over the wiring's concealing surface. Numerous marks made on various locations of the concealing surface will trace the path of the wiring of interest. 4 figs.

An investigation of localised surface plasmon resonance (LSPR) of Ag nanoparticles produced by pulsed laser deposition (PLD) technique

NASA Astrophysics Data System (ADS)

Gezgin, Serap Yiǧit; Kepceoǧlu, Abdullah; Kılıç, Hamdi Şükür

2017-02-01

Noble metal nano-structures such as Ag, Cu, Au are used commonly to increase power conversion efficiency of the solar cell by using their surface plasmons. The plasmonic metal nanoparticles of Ag among others that have strong LSPR in near UV range. They increase photon absorbance via embedding in the active semiconductor of the solar cell. Thin films of Ag are grown in the desired particle size and interparticle distance easily and at low cost by PLD technique. Ag nanoparticle thin films were grown on micro slide glass at 25-36 mJ laser pulse energies under by PLD using ns-Nd:YAG laser. The result of this work have been presented by carrying out UV-VIS and AFM analysis. It was concluded that a laser energy increases, the density and size of Ag-NPs arriving on the substrate increases, and the interparticle distance was decreases. Therefore, LSPR wavelength shifts towards to longer wavelength region.

Silver (Ag) Transport Mechanisms in TRISO Coated Particles: A Critical Review

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

IJ van Rooyen; ML Dunzik-Gougar; PM van Rooyen

2014-05-01

Transport of 110mAg in the intact SiC layer of TRISO coated particles has been studied for approximately 30 years without arriving at a satisfactory explanation of the transport mechanism. In this paper the possible mechanisms postulated in previous experimental studies, both in-reactor and out-of reactor research environment studies are critically reviewed and of particular interest are relevance to very high temperature gas reactor operating and accident conditions. Among the factors thought to influence Ag transport are grain boundary stoichiometry, SiC grain size and shape, the presence of free silicon, nano-cracks, thermal decomposition, palladium attack, transmutation products, layer thinning and coatedmore » particle shape. Additionally new insight to nature and location of fission products has been gained via recent post irradiation electron microscopy examination of TRISO coated particles from the DOE’s fuel development program. The combined effect of critical review and new analyses indicates a direction for investigating possible the Ag transport mechanism including the confidence level with which these mechanisms may be experimentally verified.« less

Silver (Ag) Transport Mechanisms in TRISO coated particles: A Critical Review

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

I J van Rooyen; J H Neethling; J A A Engelbrecht

2012-10-01

Transport of 110mAg in the intact SiC layer of TRISO coated particles has been studied for approximately 30 years without arriving at a satisfactory explanation of the transport mechanism. In this paper the possible mechanisms postulated in previous experimental studies, both in-reactor and out-of reactor research environment studies are critically reviewed and of particular interest are relevance to very high temperature gas reactor operating and accident conditions. Among the factors thought to influence Ag transport are grain boundary stoichiometry, SiC grain size and shape, the presence of free silicon, nano-cracks, thermal decomposition, palladium attack, transmutation products, layer thinning and coatedmore » particle shape. Additionally new insight to nature and location of fission products has been gained via recent post irradiation electron microscopy examination of TRISO coated particles from the DOE’s fuel development program. The combined effect of critical review and new analyses indicates a direction for investigating possible the Ag transport mechanism including the confidence level with which these mechanisms may be experimentally verified.« less

Synthesis of superior fast charging-discharging nano-LiFePO4/C from nano-FePO4 generated using a confined area impinging jet reactor approach.

PubMed

Liu, Xiao-min; Yan, Pen; Xie, Yin-Yin; Yang, Hui; Shen, Xiao-dong; Ma, Zi-Feng

2013-06-14

LiFePO4/C nanocomposites with excellent electrochemical performance is synthesized from nano-FePO4, generated by a novel method using a confined area impinging jet reactor (CIJR). When discharged at 80 C (13.6 Ag(-1)), the LiFePO4/C delivers a discharge capacity of 95 mA h g(-1), an energy density of 227 W h kg(-1) and a power density of 34 kW kg(-1).

Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation

PubMed Central

2011-01-01

In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO) were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene were characterized by SEM, TEM, and zeta potential measurements. It is confirmed that the prepared Au@PtAg alloy nanorods/graphene hybrid composites own good catalytic function for methanol electro-oxidation by cyclic voltammograms measurements, and exhibited higher catalytic activity and more stability than pure Au@Pt nanorods and Au@AgPt alloy nanorods. In conclusion, the prepared PtAg alloy nanoislands/graphene hybrid composites own high stability and catalytic activity in methanol electro-oxidation, so that it is one kind of high-performance catalyst, and has great potential in applications such as methanol fuel cells in near future. PMID:21982417

Reduced graphene oxide and Ag wrapped TiO{sub 2} photocatalyst for enhanced visible light photocatalysis

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

Leong, Kah Hon; Sim, Lan Ching; Jang, Min

2015-10-01

A well-organised reduced graphene oxide (RGO) and silver (Ag) wrapped TiO{sub 2} nano-hybrid was successfully achieved through a facile and easy route. The inherent characteristics of the synthesized RGO-Ag/TiO{sub 2} were revealed through crystalline phase, morphology, chemical composition, Raman scattering, UV-visible absorption, and photoluminescence analyses. The adopted synthesis route significantly controlled the uniform formation of silver nanoparticles and contributed for the absorption of light in the visible spectrum through localized surface plasmon resonance effects. The wrapped RGO nanosheets triggered the electron mobility and promoted visible light shift towards red spectrum. The accomplishment of synergised effect of RGO and Ag wellmore » degraded Bisphenol A under visible light irradiation with a removal efficiency of 61.9%.« less

Cable Bundle Wire Derating

NASA Technical Reports Server (NTRS)

Lundquist, Ray A.; Leidecker, Henning

1999-01-01

The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 degree C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: (1) 3.7 amps per wire (2) bundle of 15 or more wires (3) 70 C environment (4) vacuum of 10(exp -5) torr or less To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

Cable Bundle Wire Derating

NASA Technical Reports Server (NTRS)

Lundquist, Ray A.; Leidecker, Henning

1998-01-01

The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: (1) 3.7 amps per wire; (2) bundle of 15 or more wires; (3) 70 C environment: and (4) vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

Cable Bundle Wire Derating

NASA Technical Reports Server (NTRS)

Lundquist, Ray A.; Leidecker, Henning

1998-01-01

The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: 3.7 amps per wire, bundle of 15 or more wires, 70 C environment, and vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

Nano-sized Ni-doped carbon aerogel for supercapacitor.

PubMed

Lee, Yoon Jae; Jung, Ji Chul; Park, Sunyoung; Seo, Jeong Gil; Baeck, Sung-Hyeon; Yoon, Jung Rag; Yi, Jongheop; Song, In Kyu

2011-07-01

Carbon aerogel was prepared by polycondensation of resorcinol with formaldehyde using sodium carbonate as a catalyst in ambient conditions. Nano-sized Ni-doped carbon aerogel was then prepared by a precipitation method in an ethanol solvent. In order to elucidate the effect of nickel content on electrochemical properties, Ni-doped carbon aerogels (21, 35, 60, and 82 wt%) were prepared and their performance for supercapacitor electrode was investigated. Electrochemical properties of Ni-doped carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. Among the samples prepared, 35 wt% Ni-doped carbon aerogel (Ni/CA-35) showed the highest capacitance (110 F/g) and excellent charge/discharge behavior. The enhanced capacitance of Ni-doped carbon aerogel was attributed to the faradaic redox reactions of nano-sized nickel oxide. Moreover, Ni-doped carbon aerogel exhibited quite stable cyclability, indicating long-term electrochemical stability.

Investigation of anti-wear and extreme pressure properties of nano-lubricant using graphite and Ag nanoparticles.

PubMed

Choi, Youngmin; Hwang, Yujin; Park, Minchan; Lee, Jaekeun; Choi, Cheol; Jung, Mihee; Oh, Jemyung; Lee, Jung Eun

2011-01-01

The tribological behavior of graphite and Ag nanoparticles as solid additive to base oil was evaluated on a four-ball test machine and a disc-on-disc tribotester. Extreme pressure and anti-wear results are shown according to ASTM D4172 and D2783 standard methods. It is found that Ag nanoparticles have better anti-wear behavior, and especially the smaller size nanoparticle have better anti-wear behavior.

Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

NASA Astrophysics Data System (ADS)

Campillo Gloria, E.; Ederley, Vélez; Gladis, Morales; César, Hincapié; Jaime, Osorio; Oscar, Arnache; Uribe José, Ignacio; Franklin, Jaramillo

2017-06-01

The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ~ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated.

Failure Mechanisms of Thermomechanically Loaded SnAgCu/Plastic Core Solder Ball Composite Joints in Low-Temperature Co-Fired Ceramic/Printed Wiring Board Assemblies

NASA Astrophysics Data System (ADS)

Nousiainen, O.; Putaala, J.; Kangasvieri, T.; Rautioaho, R.; Vähäkangas, J.

2007-03-01

The thermal fatigue endurance of completely lead-free 95.5Sn4Ag0.7Cu/plastic core solder ball (PCSB) composite joint structures in low-temperature Co-fired ceramic/printed wiring board (LTCC/PWB) assemblies was investigated using thermal cycling tests over the temperature ranges of -40°C 125°C and 0°C 100°C. Two separate creep/fatigue failures initiated and propagated in the joints during the tests: (1) a crack along the intermetallic compound (IMC)/solder interface on the LTCC side of the joint, which formed at the high-temperature extremes; and (2) a crack in the solder near the LTCC solder land, which formed at the low-temperature extremes. Moreover, localized recrystallization was detected at the outer edge of the joints that were tested in the harsh (-40°C 125°C) test conditions. The failure mechanism was creep/fatigue-induced mixed intergranular and transgranular cracking in the recrystallized zone, but it was dominated by transgranular thermal fatigue failure beyond the recrystallized zone. The change in the failure mechanism increased the rate of crack growth. When the lower temperature extreme was raised from -40°C to 0°C, no recrystallized zone was detected and the failure was due to intergranular cracks.

Fabrication of (Ba,K)Fe2As2 tapes by ex situ PIT process using Ag-Sn alloy single sheath

NASA Astrophysics Data System (ADS)

Togano, K.; Gao, Z.; Matsumoto, A.; Kikuchi, A.; Kumakura, H.

2017-01-01

Instead of ordinal pure Ag, Ag-based Sn binary alloys (up to 7.5 at%Sn) with higher mechanical strength are used for the sheath material of ex situ powder-in-tube (PIT)-processed (Ba,K)Fe2As2(Ba-122) tapes. We found that the use of the Ag-Sn alloy enhances the densification and texturing of the Ba-122 core, resulting in higher transport, J c. Moreover, the optimum heat treatment temperature for a high J c can be lowered by around 100 °C due to the higher packing density of the Ba-122 core prior to the final heat treatment. We also found that the smoothness of the interface between the sheath and Ba-122 core is significantly improved by using the Ag-Sn binary alloy sheaths. These results show that the Ag-Sn alloy is promising as a sheath material in PIT-processed Ba-122 superconducting wires.

An excitatory paraventricular nucleus to AgRP neuron circuit that drives hunger.

PubMed

Krashes, Michael J; Shah, Bhavik P; Madara, Joseph C; Olson, David P; Strochlic, David E; Garfield, Alastair S; Vong, Linh; Pei, Hongjuan; Watabe-Uchida, Mitsuko; Uchida, Naoshige; Liberles, Stephen D; Lowell, Bradford B

2014-03-13

Hunger is a hard-wired motivational state essential for survival. Agouti-related peptide (AgRP)-expressing neurons in the arcuate nucleus (ARC) at the base of the hypothalamus are crucial to the control of hunger. They are activated by caloric deficiency and, when naturally or artificially stimulated, they potently induce intense hunger and subsequent food intake. Consistent with their obligatory role in regulating appetite, genetic ablation or chemogenetic inhibition of AgRP neurons decreases feeding. Excitatory input to AgRP neurons is important in caloric-deficiency-induced activation, and is notable for its remarkable degree of caloric-state-dependent synaptic plasticity. Despite the important role of excitatory input, its source(s) has been unknown. Here, through the use of Cre-recombinase-enabled, cell-specific neuron mapping techniques in mice, we have discovered strong excitatory drive that, unexpectedly, emanates from the hypothalamic paraventricular nucleus, specifically from subsets of neurons expressing thyrotropin-releasing hormone (TRH) and pituitary adenylate cyclase-activating polypeptide (PACAP, also known as ADCYAP1). Chemogenetic stimulation of these afferent neurons in sated mice markedly activates AgRP neurons and induces intense feeding. Conversely, acute inhibition in mice with caloric-deficiency-induced hunger decreases feeding. Discovery of these afferent neurons capable of triggering hunger advances understanding of how this intense motivational state is regulated.

Mesoporous NiCo2O4 nano-needles supported by 3D interconnected carbon network on Ni foam for electrochemical energy storage

NASA Astrophysics Data System (ADS)

Lu, Congxiang; Liu, Wen-wen; Pan, Hui; Tay, Beng Kang; Wang, Xingli; Liang, Kun; Wei, Xuezhe

2018-05-01

In this work, a three dimensional (3D) interconnected carbon network consisting of ultrathin graphite (UG) and carbon nanotubes (CNTs) on Ni foam is fabricated and employed as a novel type of substrate for mesoporous NiCo2O4 nano-needles. The successfully synthesized NiCo2O4 nano-needles/CNTs/UG on Ni foam has many advantages including facile electrolyte access and direct conducting pathways towards current collectors, which enable it to be a promising electrode material in battery-like electrochemical energy storage. Encouragingly, a high capacity of 135.1 mAh/g at the current density of 1 A/g, superior rate performance and also stable cycling for 1200 cycles at the current density of 5 A/g have been demonstrated in this novel material.

Two-Wire to Four-Wire Audio Converter

NASA Technical Reports Server (NTRS)

Talley, G. L., Jr; Seale, B. L.

1983-01-01

Simple circuit provides interface between normally incompatible voicecommunication lines. Circuit maintains 40 dB of isolation between input and output halves of four-wire line permitting two-wire line to be connected. Balancing potentiometer, Rg, adjusts gain of IC2 to null feed through from input to output. Adjustment is done on workbench just after assembly.

Electronic and Thermal Effects in the Insulator-Metal Phase Transition in VO2 Nano-Gap Junctions

DTIC Science & Technology

2014-11-27

VO2 , air, or SiO2, the 2 -0.50 -0.25 0.00 0.25 0.50 0 2 4 6 V Gap V App V o lt ag e (V ) time (ms) t p V I→M V M→I 100 400 700 1000 0.0 2.5 5.0 7.5...Electronic and thermal effects in the insulator-metal phase transition in VO2 nano-gap junctions Arash Joushaghani,1 Junho Jeong,1 Suzanne Paradis,2...Canada (Dated: 27 November 2014) By controlling the thermal transport of VO2 nano-gap junctions using device geometry, contact material, and applied

2. TYPICAL OVERHEAD WIRE CONSTRUCTION CURVE GUY WIRE ARRANGEMENT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. TYPICAL OVERHEAD WIRE CONSTRUCTION - CURVE GUY WIRE ARRANGEMENT (ABANDONED WEST LEG OF WYE AT SIXTH AVENUE AND PINE STREET) - Yakima Valley Transportation Company Interurban Railroad, Trackage, Yakima, Yakima County, WA

Wire-inhomogeneity detector

DOEpatents

Gibson, G.H.; Smits, R.G.; Eberhard, P.H.

1982-08-31

A device for uncovering imperfections in electrical conducting wire, particularly superconducting wire, by detecting variations in eddy currents. Eddy currents effect the magnetic field in a gap of an inductor, contained in a modified commercial ferrite core, through which the wire being tested is passed. A small increase or decrease in the amount of conductive material, such as copper, in a fixed cross section of wire will unbalance a bridge used to measure the impedance of the inductor, tripping a detector and sounding an alarm.

Wire Test Grip Fixture

NASA Technical Reports Server (NTRS)

Burke, Christopher S.

2011-01-01

Wire-testing issues, such as the gripping strains imposed on the wire, play a critical role in obtaining clean data. In a standard test frame fitted with flat wedge grips, the gripping action alone creates stresses on the wire specimen that cause the wire to fail at the grip location. A new test frame, which is outfitted with a vacuum chamber, negated the use of any conventional commercially available wire test fixtures, as only 7 in. (17.8 cm) existed between the grip faces. An innovative grip fixture was designed to test thin gauge wire for a variety of applications in an existing Instron test frame outfitted with a vacuum chamber.

Effect of temperature on the nano/microstructure and mechanical behavior of nanotwinned Ag films

DOE PAGES

Zhang, Huan; Geng, Jie; Ott, Ryan T.; ...

2015-06-24

In situ and ex situ annealed nanotwinned (NT) Ag thin films have been investigated by TEM and tensile testing to reveal the thermal stability of the twin boundaries, grain boundaries, dislocation densities, and their respective influence of the macroscopic yield stress. The NT Ag films synthesized by magnetron sputtering form both coherent (CTB, Σ3{111}) and incoherent (ITB, Σ3{112}) twin boundaries that are thermally stable up to 473 K (200 Celsius), i.e., no obvious changes in grain size, twin spacing, and yield stress. In situ TEM observations show the dislocations become mobile at 453 K (180 Celsius) resulting in dislocation annihilationmore » primarily at twin and grain boundaries. Rotation of grains with low-angle grain boundaries was observed during in situ heating, resulting in the growth of columnar grains above 453 K (180 Celsius). However, no noticeable changes in the spacings of CTBs were observed during the entire in situ and ex situ annealing [up to 873 K (600 Celsius)]. The increase in grain size and concomitant decrease in yield stress following annealing at various temperatures can be described by the Hall-Petch relationship, demonstrating that grain size rather than twin spacing is most sensitive to thermal annealing and plays a dominant role in the deformation of NT Ag films.« less

Interaction between Silver Nanoparticles and Spinach Leaf

NASA Astrophysics Data System (ADS)

Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

2013-12-01

Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. Cyto

Wire ablation dynamics model and its application to imploding wire arrays of different geometries.

PubMed

Esaulov, A A; Kantsyrev, V L; Safronova, A S; Velikovich, A L; Shrestha, I K; Williamson, K M; Osborne, G C

2012-10-01

The paper presents an extended description of the amplified wire ablation dynamics model (WADM), which accounts in a single simulation for the processes of wire ablation and implosion of a wire array load of arbitrary geometry and wire material composition. To investigate the role of wire ablation effects, the implosions of cylindrical and planar wire array loads at the university based generators Cobra (Cornell University) and Zebra (University of Nevada, Reno) have been analyzed. The analysis of the experimental data shows that the wire mass ablation rate can be described as a function of the current through the wire and some coefficient defined by the wire material properties. The aluminum wires were found to ablate with the highest rate, while the copper ablation is the slowest one. The lower wire ablation rate results in a higher inward velocity of the ablated plasma, a higher rate of the energy coupling with the ablated plasma, and a more significant delay of implosion for a heavy load due to the ablation effects, which manifest the most in a cylindrical array configuration and almost vanish in a single-planar array configuration. The WADM is an efficient tool suited for wire array load design and optimization in wide parameter ranges, including the loads with specific properties needed for the inertial confinement fusion research and laboratory astrophysics experiments. The data output from the WADM simulation can be used to simplify the radiation magnetohydrodynamics modeling of the wire array plasma.

Windows: Life after Wire.

ERIC Educational Resources Information Center

Razwick, Jerry

2003-01-01

Although wired glass is extremely common in school buildings, the International Building Code adopted new standards that eliminate the use of traditional wired glass in K-12 schools, daycare centers, and athletic facilities. Wired glass breaks easily, and the wires can cause significant injuries by forming dangerous snags when the glass breaks.…

The Influence of Nano-Scale Silicon Nitride Additions on the Physical and Magnetic Properties of Iron Sheathed Magnesium Boride Wires

NASA Astrophysics Data System (ADS)

Zhu, W.; Cave, J.

2006-03-01

The enhancement of flux line pinning in magnesium boride wires is a critical issue for their future applications in devices and machines. It is well known that small size dopants can significantly influence the current densities of these materials. Here, the influence of nanometric (<30nm) silicon nitride on physical properties and current density is presented. The iron-sheathed powder in tube wires were prepared using pure magnesium and boron powders with silicon nitride additions. The wires were rolled flat and treated at up to 900 degrees C in flowing argon. SEM and XRD were used to identify phases and microstructures. Magnetization critical currents, up to several 100 of thousands A/cm2, at various temperatures and fields (5K - 20K and up to 3 tesla) show that there are competing mechanisms from chemical and flux pinning effects.

Dual wire welding torch and method

DOEpatents

Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

2009-04-28

A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

Wire-guided sphincterotomy.

PubMed

Sherman, S; Uzer, M F; Lehman, G A

1994-12-01

Guidewire-assisted techniques have acquired an important role in endoscopic interventions in the pancreaticobiliary tree. The wire-guided sphincterotome allows the endoscopist to maintain direct access to the biliary tree before or after the sphincterotomy. It has the additional advantages of allowing for more expeditious placement of accessories and being useful in combined percutaneous-endoscopic procedures. There are two basic designs of wire-guided sphincterotomes. The single-channel model has a single lumen for both the cutting wire and guidewire and requires guidewire removal before the application of power. The double-channel model has two separate lumens for the guidewire and stainless steel cutting wire. In vitro data suggest that significant capacitive coupling currents (or short circuits) may occur on the standard Teflon-coated guidewire when used with a double lumen sphincterotome, resulting in electrosurgical burns. Thus, the manufacturers of the double-lumen models recommend removing the Teflon-coated wire before performing sphincterotomy. Although limited data in humans have been published, it appears that wire-guided sphincterotomy and standard sphincterotomy have similar complication rates. More safety information in humans is awaited.

Modulation of the Proteasome Pathway by Nano-Curcumin and Curcumin in Retinal Pigment Epithelial Cells.

PubMed

Ramos de Carvalho, J Emanuel; Verwoert, Milan T; Vogels, Ilse M C; Schipper-Krom, Sabine; Van Noorden, Cornelis J F; Reits, Eric A; Klaassen, Ingeborg; Schlingemann, Reinier O

2018-01-01

Curcumin has multiple biological effects including the modulation of protein homeostasis by the ubiquitin-proteasome system. The purpose of this study was to assess the in vitro cytotoxic and oxidative effects of nano-curcumin and standard curcumin and characterize their effects on proteasome regulation in retinal pigment epithelial (RPE) cells. Viability, cell cycle progression, and reactive oxygen species (ROS) production were determined after treatment with nano-curcumin or curcumin. Subsequently, the effects of nano-curcumin and curcumin on proteasome activity and the gene and protein expression of proteasome subunits PA28α, α7, β5, and β5i were assessed. Nano-curcumin (5-100 μM) did not show significant cytotoxicity or anti-oxidative effects against H2O2-induced oxidative stress, whereas curcumin (≥10 μM) was cytotoxic and a potent inducer of ROS production. Both nano-curcumin and curcumin induced changes in proteasome-mediated proteolytic activity characterized by increased activity of the proteasome subunits β2 and β5i/β1 and reduced activity of β5/β1i. Likewise, nano-curcumin and curcumin affected mRNA and protein levels of household and immunoproteasome subunits. Nano-curcumin is less toxic to RPE cells and less prone to induce ROS production than curcumin. Both nano-curcumin and curcumin increase proteasome-mediated proteolytic activity. These results suggest that nano-curcumin may be regarded as a proteasome-modulating agent of limited cytotoxicity for RPE cells. The Author(s). Published by S. Karger AG, Basel.

U.S. Navy Wire-Rope Handbook. Volume 2. Wire-Rope Analysis and Design Data

DTIC Science & Technology

1976-01-01

beneficial from the standpoint of wire - bending stress. How- ever, there is a design trade-off here in that the smaller L/d becomes, the lower are the...wires of a rope, it is first necessary to determine the radii of curvature of the wires prior to and after bending the rope. The wire - bending stress can... wire bending stress. 4.3. CONTACT STRESSES Contact stresses in a wire rope are one of the most important determinants of its fatigue life and are, by far

Chitosan-hyaluronic acid/nano silver composite sponges for drug resistant bacteria infected diabetic wounds.

PubMed

Anisha, B S; Biswas, Raja; Chennazhi, K P; Jayakumar, R

2013-11-01

The aim of this work was to develop an antimicrobial sponge composed of chitosan, hyaluronic acid (HA) and nano silver (nAg) as a wound dressing for diabetic foot ulcers (DFU) infected with drug resistant bacteria. nAg (5-20 nm) was prepared and characterized. The nanocomposite sponges were prepared by homogenous mixing of chitosan, HA and nAg followed by freeze drying to obtain a flexible and porous structure. The prepared sponges were characterized using SEM and FT-IR. The porosity, swelling, biodegradation and haemostatic potential of the sponges were also studied. Antibacterial activity of the prepared sponges was analysed using Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Klebsiella pneumonia. Chitosan-HA/nAg composite sponges showed potent antimicrobial property against the tested organisms. Sponges containing higher nAg (0.005%, 0.01% and 0.02%) concentrations showed antibacterial activity against MRSA. Cytotoxicity and cell attachment studies were done using human dermal fibroblast cells. The nanocomposite sponges showed a nAg concentration dependent toxicity towards fibroblast cells. Our results suggest that this nanocomposite sponges could be used as a potential material for wound dressing for DFU infected with antibiotic resistant bacteria if the optimal concentration of nAg exhibiting antibacterial action with least toxicity towards mammalian cells is identified. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of Baseplates of Orthodontic Appliances with in situ generated Silver Nanoparticles on Cariogenic Bacteria: A Randomized, Double-blind Cross-over Clinical Trial.

PubMed

Ghorbanzadeh, Roghayeh; Pourakbari, Babak; Bahador, Abbas

2015-04-01

Polymethyl-methacrylate (PMMA) is commonly used primarily for baseplates of orthodontic appliances (BOA). The activities of cariogenic bacteria in biofilm on these surfaces may contribute to dental caries, gingival inflammation and periodontal disease. The PMMA incorporated with nanoparticles of silver (NanoAg-I-PMMA) and NanoAg in situ in PMMA (NanoAg-IS-PMMA) have been shown to control the growth of cariogenic bacteria, but clinical trial of anti-cariogenic application of these novel materials in orthodontics has not been evaluated. The main aim of the study is to compare the clinical effectiveness of using NanoAg-IS-PMMA and NanoAg-I-PMMA for construction of new BOA in inhibiting the planktonic growth and biofilm formation of the cariogenic bacteria. Twenty four patients with a median age of 12.6 years (7-15) harboring Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus as well as Lactobacillus casei participated in the randomized, double-blind, cross-over study. The experimental BOA, NanoAg-IS-BOA and NanoAg-I-BOA, contained 0.5% w/w NanoAg while the control BOA was standard PMMA. Antibacterial effect of NanoAg-IS-BOA and NanoAg-I-BOA was assessed against test cariogenic bacteria by planktonic and biofilm bacterial cells growth inhibition. The average levels of test cariogenic bacteria in saliva decreased about 2 to 70 fold (30.9-98.4%) compared to baseline depending on the microorganism type and test BOA. Biofilm inhibition analysis demonstrated that NanoAg-I-BOA and NanoAg-IS-BOA inhibited the biofilm of all test bacteria by 20.1 to 79.9% compared to BOA. NanoAg-IS-BOA had a strong anti-biofilm effect against S. mutans, S. sobrinus and L. casei. However, NanoAg-I-BOA showed only slight anti-biofilm effects on test bacteria. Most notably, at all period of the clinical trial, NanoAg-IS-BOA showed a higher antibacterial activity than NanoAg-I-BOA. Based on the novel data that presented here, the NanoAg-IS-BOA had strong antimicrobial

Effect of Post-annealing on the Electrochromic Properties of Layer-by-Layer Arrangement FTO-WO3-Ag-WO3-Ag

NASA Astrophysics Data System (ADS)

Hoseinzadeh, S.; Ghasemiasl, R.; Bahari, A.; Ramezani, A. H.

2018-03-01

In the current study, composites of tungsten trioxide (W03) and silver (Ag) are deposited in a layer-by-layer electrochromic (EC) arrangement onto a fluorine-doped tin oxide coated glass substrate. Tungsten oxide nanoparticles are an n-type semiconductor that can be used as EC cathode material. Nano-sized silver is a metal that can serve as an electron trap center that facilitates charge departure. In this method, the WO3 and Ag nanoparticle powder were deposited by physical vapor deposition onto the glass substrate. The fabricated electrochromic devices (ECD) were post-annealed to examine the effect of temperature on their EC properties. The morphology of the thin film was characterized by scanning electron microscopy and atomic force microscopy. Structural analysis showed that the addition of silver dopant increased the size of the aggregation of the film. The film had an average approximate roughness of about 17.8 nm. The electro-optical properties of the thin film were investigated using cyclic voltammetry and UV-visible spectroscopy to compare the effects of different post-annealing temperatures. The ECD showed that annealing at 200°C provided better conductivity (maximum current of about 90 mA in the oxidation state) and change of transmittance (ΔT = 90% at the continuous switching step) than did the other thin films. The optical band gaps of the thin film showed that it allowed direct transition at 3.85 eV. The EC properties of these combinations of coloration efficiency and response time indicate that the WO3-Ag-WO3-Ag arrangement is a promising candidate for use in such ECDs.

Fine-tunable plasma nano-machining for fabrication of 3D hollow nanostructures: SERS application

NASA Astrophysics Data System (ADS)

Mehrvar, L.; Hajihoseini, H.; Mahmoodi, H.; Tavassoli, S. H.; Fathipour, M.; Mohseni, S. M.

2017-08-01

Novel processing sequences for the fabrication of artificial nanostructures are in high demand for various applications. In this paper, we report on a fine-tunable nano-machining technique for the fabrication of 3D hollow nanostructures. This technique originates from redeposition effects occurring during Ar dry etching of nano-patterns. Different geometries of honeycomb, double ring, nanotube, cone and crescent arrays have been successfully fabricated from various metals such as Au, Ag, Pt and Ti. The geometrical parameters of the 3D hollow nanostructures can be straightforwardly controlled by tuning the discharge plasma pressure and power. The structure and morphology of nanostructures are probed using atomic force microscopy (AFM), scanning electron microscopy (SEM), optical emission spectroscopy (OES) and energy dispersive x-ray spectroscopy (EDS). Finally, a Ag nanotube array was assayed for application in surface enhanced Raman spectroscopy (SERS), resulting in an enhancement factor (EF) of 5.5 × 105, as an experimental validity proof consistent with the presented simulation framework. Furthermore, it was found that the theoretical EF value for the honeycomb array is in the order of 107, a hundred times greater than that found in nanotube array.

Next Generation Wiring

NASA Technical Reports Server (NTRS)

Medelius, Petro; Jolley, Scott; Fitzpatrick, Lilliana; Vinje, Rubiela; Williams, Martha; Clayton, LaNetra; Roberson, Luke; Smith, Trent; Santiago-Maldonado, Edgardo

2007-01-01

Wiring is a major operational component on aerospace hardware that accounts for substantial weight and volumetric space. Over time wire insulation can age and fail, often leading to catastrophic events such as system failure or fire. The next generation of wiring must be reliable and sustainable over long periods of time. These features will be achieved by the development of a wire insulation capable of autonomous self-healing that mitigates failure before it reaches a catastrophic level. In order to develop a self-healing insulation material, three steps must occur. First, methods of bonding similar materials must be developed that are capable of being initiated autonomously. This process will lead to the development of a manual repair system for polyimide wire insulation. Second, ways to initiate these bonding methods that lead to materials that are similar to the primary insulation must be developed. Finally, steps one and two must be integrated to produce a material that has no residues from the process that degrades the insulating properties of the final repaired insulation. The self-healing technology, teamed with the ability to identify and locate damage, will greatly improve reliability and safety of electrical wiring of critical systems. This paper will address these topics, discuss the results of preliminary testing, and remaining development issues related to self-healing wire insulation.

Wire-in-tube structure fabricated by single capillary electrospinning via nanoscale Kirkendall effect: the case of nickel-zinc ferrite.

PubMed

Fu, Jiecai; Zhang, Junli; Peng, Yong; Zhao, Changhui; He, Yongmin; Zhang, Zhenxing; Pan, Xiaojun; Mellors, Nigel J; Xie, Erqing

2013-12-21

Wire-in-tube structures have previously been prepared using an electrospinning method by means of tuning hydrolysis/alcoholysis of a precursor solution. Nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4) nanowire-in-nanotubes have been prepared as a demonstration. The detailed nanoscale characterization, formation process and magnetic properties of Ni0.5Zn0.5Fe2O4 nanowire-in-nanotubes has been studied comprehensively. The average diameters of the outer tubes and inner wires of Ni0.5Zn0.5Fe2O4 nanowire-in-nanotubes are around 120 nm and 42 nm, respectively. Each fully calcined individual nanowire-in-nanotube, either the outer-tube or the inner-wire, is composed of Ni0.5Zn0.5Fe2O4 monocrystallites stacked along the longitudinal direction with random orientation. The process of calcining electrospun polymer composite nanofibres can be viewed as a morphologically template nucleation and precursor diffusion process. This allows the nitrates precursor to diffuse toward the surface of the nanofibres while the oxides (decomposed from hydroxides and nitrates) products diffuse to the core region of the nanofibres; the amorphous nanofibres transforming thereby into crystalline nanowire-in-nanotubes. In addition, the magnetic properties of the Ni0.5Zn0.5Fe2O4 nanowire-in-nanotubes were also examined. It is believed that this nanowire-in-nanotube (sometimes called core-shell) structure, with its uniform size and well-controlled orientation of the long nanowire-in-nanotubes, is particularly attractive for use in the field of nano-fluidic devices and nano-energy harvesting devices.

International space station wire program

NASA Technical Reports Server (NTRS)

May, Todd

1995-01-01

Hardware provider wire systems and current wire insulation issues for the International Space Station (ISS) program are discussed in this viewgraph presentation. Wire insulation issues include silicone wire contamination, Tefzel cold temperature flexibility, and Russian polyimide wire insulation. ISS is a complex program with hardware developed and managed by many countries and hundreds of contractors. Most of the obvious wire insulation issues are known by contractors and have been precluded by proper selection.

Kirschner wire bending.

PubMed

Firoozabadi, Reza; Kramer, Patricia A; Benirschke, Stephen K

2013-11-01

Although Kirschner wires are useful implants in many situations, migration of the wire and irritation of the surrounding soft tissues are common complications. Seven steps are described herein, which result in a Kirschner wire that is bent 180° angle, providing a smooth anchor into bone. Use of this technique produces implants that provide stable fixation with few soft tissue complications.

Laser Wire Stripper

NASA Technical Reports Server (NTRS)

1983-01-01

NASA-developed space shuttle technology is used in a laser wire stripper designed by Raytheon Company. Laser beams cut through insulation on a wire without damaging conductive metal, because laser radiation that melts plastic insulation is reflected by the metal. The laser process is fast, clean, precise and repeatable. It eliminates quality control problems and the expense of rejected wiring.

Bactericidal impact of Ag, ZnO and mixed AgZnO colloidal nanoparticles on H37Rv Mycobacterium tuberculosis phagocytized by THP-1 cell lines.

PubMed

Jafari, Alireza; Mosavari, Nader; Movahedzadeh, Farahnaz; Nodooshan, Saeedeh Jafari; Safarkar, Roya; Moro, Rossella; Kamalzadeh, Morteza; Majidpour, Ali; Boustanshenas, Mina; Mosavi, Tahereh

2017-09-01

The purpose of this research project was to infection of human macrophages (THP-1) cell lines by H 37 Rv strain of Mycobacterium tuberculosis (H 37 RvMTB) and find out the ratio/dilution of mixture silver (Ag NPs) and zinc oxide nanoparticles (ZnO NPs) whose ability to eliminate phagocytized bacteria compared to rifampicin. The colloidal Ag NPs and ZnO NPs were synthesized and their characteristics were evaluated. The THP-1 cell lines were infected with different concentration of H 37 RvMTB. Next, the infected cells were treated with different ratios/dilutions of Ag NPs, ZnO NPs and rifampicin. The THP-1 were lysed and were cultured in Lowenstein-Jensen agar medium, for eight weeks. The TEM and AFM images of NPs and H 37 RvMTB were supplied. It is observed that Ag NPs, 2 Ag :8 ZnO and 8 Ag :2 ZnO did not have any anti-tubercular effects on phagocytized H 37 RvMTB. Conversely, ZnO NPs somehow eliminated 18.7 × 10 4  CFU ml -1 of H 37 RvMTB in concentration of ∼ 0.468 ppm. To compare with 40 ppm of rifampicin, ∼ 0.663 ppm of 5 Ag :5 ZnO had the ability to kill of H 37 RvMTB, too. Based on previous research, ZnO NPs had strong anti-tubercular impact against H 37 RvMTB to in-vitro condition, but it was toxic in concentration of ∼ 0.468 ppm to both of THP-1 and normal lung (MRC-5) cell lines. It also seems that 5 Ag :5 ZnO is justified because in concentration of ∼ 0.663 ppm of 5 Ag :5 ZnO , phagocytized H 37 RvMTB into the THP-1 had died without any toxicity effects against THP-1 and also MRC-5 cell lines. It is obvious that the mixture of colloidal silver and zinc oxide NPs with ratio of 5 Ag :5 ZnO would be trustworthy options as anti-tubercular nano-drugs in future researches. Copyright © 2017. Published by Elsevier Ltd.

High-voltage nano-oxidation in deionized water and atmospheric environments by atomic force microscopy.

PubMed

Huang, Jen-Ching; Chen, Chung-Ming

2012-01-01

This study used atomic force microscopy (AFM), metallic probes with a nanoscale tip, and high-voltage generators to investigate the feasibility of high-voltage nano-oxidation processing in deionized water (DI water) and atmospheric environments. Researchers used a combination of wire-cutting and electrochemical etching to transform a 20-μm-thick stainless steel sheet into a conductive metallic AFM probe with a tip radius of 60 nm, capable of withstanding high voltages. The combination of AFM, high-voltage generators, and nanoscale metallic probes enabled nano-oxidation processing at 200 V in DI water environments, producing oxides up to 66.6 nm in height and 467.03 nm in width. Oxides produced through high-voltage nano-oxidation in atmospheric environments were 117.29 nm in height and 551.28 nm in width, considerably exceeding the dimensions of those produced in DI water. An increase in the applied bias voltage led to an apparent logarithmic increase in the height of the oxide dots in the range of 200-400 V. The performance of the proposed high-voltage nano-oxidation technique was relatively high with seamless integration between the AFM machine and the metallic probe fabricated in this study. © Wiley Periodicals, Inc.

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi 2Sr 2CaCu 2O x multifilament round wires

DOE PAGES

Ye, Liyang; Li, Pei; Jaroszynski, Jan; ...

2016-12-01

The critical current of many practical superconductors is sensitive to strain, and this sensitivity is exacerbated during a quench that induces a peak local strain which can be fatal to superconducting magnets. Here, a new method is introduced to quantify the influence of the conductor stress and strain state during normal operation on the margin to degradation during a quench, as measured by the maximum allowable hot spot temperature T allowable, for composite wires within superconducting magnets. The first conductor examined is Ag-sheathed Bi 2Sr 2CaCu 2O x round wire carrying high engineering critical current density, J E, of 550more » A mm -2 at 4.2 K and 15 T. The critical axial tensile stress of this conductor is determined to be 150 MPa and, in the absence of Lorentz forces, T allowable is greater than 450 K. With increasing axial tensile stress, σ a, however, T allowable decreases nonlinearly, dropping to 280 K for σ a = 120 MPa and to 160 K for σ a = 145 MPa. T allowable(σ a) is shown to be nonlinear and independent of magnetic field from 15 to 30 T. T allowable(σ a) dictates the balance between magnetic field generation, which increases with the magnet operating current and stress, and the safety margin, which decreases with decreasing T allowable, and therefore has important engineering value. Lastly, it is also shown that T allowable(σ a) can be predicted accurately by a general strain model, showing that strain control is the key to preventing degradation of superconductors during a quench.« less

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi 2Sr 2CaCu 2O x multifilament round wires

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

Ye, Liyang; Li, Pei; Jaroszynski, Jan

The critical current of many practical superconductors is sensitive to strain, and this sensitivity is exacerbated during a quench that induces a peak local strain which can be fatal to superconducting magnets. Here, a new method is introduced to quantify the influence of the conductor stress and strain state during normal operation on the margin to degradation during a quench, as measured by the maximum allowable hot spot temperature T allowable, for composite wires within superconducting magnets. The first conductor examined is Ag-sheathed Bi 2Sr 2CaCu 2O x round wire carrying high engineering critical current density, J E, of 550more » A mm -2 at 4.2 K and 15 T. The critical axial tensile stress of this conductor is determined to be 150 MPa and, in the absence of Lorentz forces, T allowable is greater than 450 K. With increasing axial tensile stress, σ a, however, T allowable decreases nonlinearly, dropping to 280 K for σ a = 120 MPa and to 160 K for σ a = 145 MPa. T allowable(σ a) is shown to be nonlinear and independent of magnetic field from 15 to 30 T. T allowable(σ a) dictates the balance between magnetic field generation, which increases with the magnet operating current and stress, and the safety margin, which decreases with decreasing T allowable, and therefore has important engineering value. Lastly, it is also shown that T allowable(σ a) can be predicted accurately by a general strain model, showing that strain control is the key to preventing degradation of superconductors during a quench.« less

AgPO2F2 and Ag9(PO2F2)14: the first Ag(i) and Ag(i)/Ag(ii) difluorophosphates with complex crystal structures.

PubMed

Malinowski, Przemysław J; Kurzydłowski, Dominik; Grochala, Wojciech

2015-12-07

The reaction of AgF2 with P2O3F4 yields a mixed valence Ag(I)/Ag(II) difluorophosphate salt with AgAg(PO2F2)14 stoichiometry - the first Ag(ii)-PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(ii)-PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric Ag(PO2F2)14(4-) anions and two types of Ag(I) cations. One particular Ag(II) site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(ii) in an oxo-ligand environment. Ag(i)PO2F2 - the product of the thermal decomposition of Ag9(PO2F2)14 - has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [Ag(I)O4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2(-) anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations.

Wire harness twisting aid

NASA Technical Reports Server (NTRS)

Casey, E. J.; Commadore, C. C.; Ingles, M. E.

1980-01-01

Long wire bundles twist into uniform spiral harnesses with help of simple apparatus. Wires pass through spacers and through hand-held tool with hole for each wire. Ends are attached to low speed bench motor. As motor turns, operator moves hand tool away forming smooth twists in wires between motor and tool. Technique produces harnesses that generate less radio-frequency interference than do irregularly twisted cables.

Reliability Criteria for Thick Bonding Wire.

PubMed

Dagdelen, Turker; Abdel-Rahman, Eihab; Yavuz, Mustafa

2018-04-17

Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire.

Reliability Criteria for Thick Bonding Wire

PubMed Central

Yavuz, Mustafa

2018-01-01

Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire. PMID:29673194

30 CFR 75.1003-1 - Other requirements for guarding of trolley wires and trolley feeder wires.

Code of Federal Regulations, 2010 CFR

2010-07-01

... wires and trolley feeder wires. 75.1003-1 Section 75.1003-1 Mineral Resources MINE SAFETY AND HEALTH... Trolley Wires and Trolley Feeder Wires § 75.1003-1 Other requirements for guarding of trolley wires and trolley feeder wires. Adequate precaution shall be taken to insure that equipment being moved along...

30 CFR 75.1003-1 - Other requirements for guarding of trolley wires and trolley feeder wires.

Code of Federal Regulations, 2011 CFR

2011-07-01

... wires and trolley feeder wires. 75.1003-1 Section 75.1003-1 Mineral Resources MINE SAFETY AND HEALTH... Trolley Wires and Trolley Feeder Wires § 75.1003-1 Other requirements for guarding of trolley wires and trolley feeder wires. Adequate precaution shall be taken to insure that equipment being moved along...

Thin wire pointing method

NASA Technical Reports Server (NTRS)

Green, G.; Mattauch, R. J. (Inventor)

1983-01-01

A method is described for forming sharp tips on thin wires, in particular phosphor bronze wires of diameters such as one-thousandth inch used to contact micron size Schottky barrier diodes, which enables close control of tip shape and which avoids the use of highly toxic solutions. The method includes dipping an end of a phosphor bronze wire into a dilute solution of sulfamic acid and applying a current through the wire to electrochemically etch it. The humidity in the room is controlled to a level of less than 50%, and the voltage applied between the wire and another electrode in the solutions is a half wave rectified voltage. The current through the wire is monitored, and the process is stopped when the current falls to a predetermined low level.

49 CFR 236.74 - Protection of insulated wire; splice in underground wire.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Protection of insulated wire; splice in underground wire. 236.74 Section 236.74 Transportation Other Regulations Relating to Transportation (Continued..., AND APPLIANCES Rules and Instructions: All Systems Wires and Cables § 236.74 Protection of insulated...

49 CFR 236.74 - Protection of insulated wire; splice in underground wire.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Protection of insulated wire; splice in underground wire. 236.74 Section 236.74 Transportation Other Regulations Relating to Transportation (Continued..., AND APPLIANCES Rules and Instructions: All Systems Wires and Cables § 236.74 Protection of insulated...

Easily-wired toggle switch

NASA Technical Reports Server (NTRS)

Dean, W. T.; Stringer, E. J.

1979-01-01

Crimp-type connectors reduce assembly and disassembly time. With design, no switch preparation is necessary and socket contracts are crimped to wires inserted in module attached to back of toggle switch engaging pins inside module to make electrical connections. Wires are easily removed with standard detachment tool. Design can accommodate wires of any gage and as many terminals can be placed on switch as wire gage and switch dimensions will allow.

Impact tensile testing of wires

NASA Technical Reports Server (NTRS)

Dawson, T. H.

1976-01-01

The test consists of fixing one end of a wire specimen and allowing a threaded falling weight to strike the other. Assuming the dynamic stress in the wire to be a function only of its strain, energy considerations show for negligible wire inertia effects that the governing dynamic stress-strain law can be determined directly from impact energy vs. wire elongation data. Theoretical calculations are presented which show negligible wire inertia effects for ratios of wire mass to striking mass of the order of .01 or less. The test method is applied to soft copper wires and the dynamic stress-strain curve so determined is found to be about 30 percent higher than the corresponding static curve.

Comparative range of orthodontic wires.

PubMed

Ingram, S B; Gipe, D P; Smith, R J

1986-10-01

ADA specification No. 32 for determining the range (elastic limit) of orthodontic wires uses the bending of a wire section treated as a cantilever beam. An alternative method for defining the range of orthodontic wires proposed by Waters (1981) is to wrap wire sections around mandrels of varying diameters and measure the deformation imparted after unwrapping. Four brass mandrels with a total of 46 test diameters ranging from 3.5 to 60.0 mm were used in this study. Wire sections 9 cm in length were rolled on the mandrel with a hand lathe. The mandrel cross section required to produce a predetermined amount of deformation (2 mm arc height for a 5 cm chord) was defined as the yield diameter for that particular wire. No individual wire was tested twice so as to avoid introduction of strain history. Test samples of 488 different orthodontic wires supplied by nine commercial distributors were evaluated (a total of 4,747 samples). Stainless steel wires of identical dimensions had a large variation in range, depending on the state of strain hardening and heat treatment. For example, 0.020 inch round wire had yield diameters ranging from 22.8 mm for Australian special plus orange (TP Laboratories) to 42.9 mm for Nubryte gold (G.A.C. International). Chromium cobalt wires had less range than stainless steel before heat treatment, but increased greatly in range after heat treatment. Nitinol (Unitek) had the greatest range of all wires tested (yield diameter of 8.7 mm for 0.016 inch Nitinol). Multistranded stainless steel wires had yield diameters between 9.0 and 14.0 mm.

Studies of friction and wear characteristics of various wires for wire-brush skids

NASA Technical Reports Server (NTRS)

Dreher, R. C.

1977-01-01

The friction and wear characteristics of 22 types and sizes of wires for potential use in wire-brush skids were studied. These characteristics were determined by placing brushes made from candidate wires on a belt sander whose moving belt simulated landing roll-out distance. At the same time, the drag force and wear behavior were monitored. Data were obtained over distances up to 3048 m (10,000 ft) at preselected bearing pressures of 172 to 1034 kPa (25 to 150 psi). In general, the friction coefficient developed by the candidate wires was found to be independent of bearing pressure and ranged between 0.4 and 0.6 under the test conditions of this investigation. The friction coefficient was not degraded when the surface was wetted and appears to be independent of wire diameter except perhaps when wire size is relatively large compared with the surface asperities. Generally, the high friction demonstrated by the soft materials was accompanied by high wear rates; conversely, the hard materials provided greater wear resistance but offered lower friction. For all test wires, the wear was shown to increase with increasing bearing pressure, in general, for the same bearing pressure, wear increased with increasing wire diameter and decreased when the surface was wetted.

Validation and sensitivity of the FINE Bayesian network for forecasting aquatic exposure to nano-silver.

PubMed

Money, Eric S; Barton, Lauren E; Dawson, Joseph; Reckhow, Kenneth H; Wiesner, Mark R

2014-03-01

The adaptive nature of the Forecasting the Impacts of Nanomaterials in the Environment (FINE) Bayesian network is explored. We create an updated FINE model (FINEAgNP-2) for predicting aquatic exposure concentrations of silver nanoparticles (AgNP) by combining the expert-based parameters from the baseline model established in previous work with literature data related to particle behavior, exposure, and nano-ecotoxicology via parameter learning. We validate the AgNP forecast from the updated model using mesocosm-scale field data and determine the sensitivity of several key variables to changes in environmental conditions, particle characteristics, and particle fate. Results show that the prediction accuracy of the FINEAgNP-2 model increased approximately 70% over the baseline model, with an error rate of only 20%, suggesting that FINE is a reliable tool to predict aquatic concentrations of nano-silver. Sensitivity analysis suggests that fractal dimension, particle diameter, conductivity, time, and particle fate have the most influence on aquatic exposure given the current knowledge; however, numerous knowledge gaps can be identified to suggest further research efforts that will reduce the uncertainty in subsequent exposure and risk forecasts. Copyright © 2013 Elsevier B.V. All rights reserved.

Splicing Wires Permanently With Explosives

NASA Technical Reports Server (NTRS)

Bement, Laurence J.; Kushnick, Anne C.

1990-01-01

Explosive joining process developed to splice wires by enclosing and metallurgically bonding wires within copper sheets. Joints exhibit many desirable characteristics, 100-percent conductivity and strength, no heat-induced annealing, no susceptibility to corrosion in contacts between dissimilar metals, and stability at high temperature. Used to join wires to terminals, as well as to splice wires. Applicable to telecommunications industry, in which millions of small wires spliced annually.

Surface induced phonon decay rates in thin film nano-structures

NASA Astrophysics Data System (ADS)

Photiadis, D. M.

2007-12-01

Nano-scale structure significantly impacts phonon transport and related phonon relaxation rates, with order of magnitude effects on the thermal conductivity of dielectric thin films and quantum wires, and even larger effects on the lifetimes of ultrasonic phonons of micro- (nano-) oscillators. In both cases, efforts to explain the data have been hampered by our lack of knowledge of the effects of confined dimensionality on phonon-phonon scattering rates. Using a phonon Boltzmann equation with appropriate boundary conditions on the free surfaces to take surface roughness into account, we have obtained an expression yielding phonon lifetimes in 2-D dielectric nanostructures(thin films) resulting from phonon-phonon scattering in conjunction with phonon-surface scattering. We present these theoretical results and, in the limit in which surface induced losses dominate, obtain explicit predictions for the phonon lifetimes. The predicted temperature dependence of the ultrason! ic loss does not explain the observed saturation of the loss at low temperatures(τ(T) → const), but does give results of the order of magnitude of measured ultrasonic lifetimes.

Fabrication of Pd-Cr wire

NASA Technical Reports Server (NTRS)

Diamond, Sidney; Leach, Dennen M.

1989-01-01

Fabrication of Pd-13 percent Cr alloy wires is described. Melting, casting, swaging and annealing processes are discussed. Drawing to reach two diameters (0.003 inch and 0.00176 inch) of wire is described. Representative micrographs of the Pd-Cr alloy at selected stages during wire fabrication are included. The resistance of the wire was somewhat lower, by about 15 to 20 percent, than comparable wire of other alloys used for strain gages.

Evaluation of mechanical properties of Aluminum-Copper cold sprayed and alloy 625 wire arc sprayed coatings

NASA Astrophysics Data System (ADS)

Bashirzadeh, Milad

This study examines microstructural-based mechanical properties of Al-Cu composite deposited by cold spraying and wire arc sprayed nickel-based alloy 625 coating using numerical modeling and experimental techniques. The microhardness and elastic modulus of samples were determined using the Knoop hardness technique. Hardness in both transverse and longitudinal directions on the sample cross-sections has been measured. An image-based finite element simulation algorithm was employed to determine the mechanical properties through an inverse analysis. In addition mechanical tests including, tensile, bending, and nano-indentation tests were performed on alloy 625 wire arc sprayed samples. Overall, results from the experimental tests are in relatively good agreement for deposited Al-Cu composites and alloy 625 coating. However, results obtained from numerical simulation are significantly higher in value than experimentally obtained results. Examination and comparison of the results are strong indications of the influence of microstructure characteristics on the mechanical properties of thermally spray deposited coatings.

46 CFR 111.60-11 - Wire.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD... Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be component insulated. (c) Wire, other than in switchboards, must meet the requirements in sections 24.6.7 and...

46 CFR 111.60-11 - Wire.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD... Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be component insulated. (c) Wire, other than in switchboards, must meet the requirements in sections 24.6.7 and...

Dual wire weld feed proportioner

NASA Technical Reports Server (NTRS)

Nugent, R. E.

1968-01-01

Dual feed mechanism enables proportioning of two different weld feed wires during automated TIG welding to produce a weld alloy deposit of the desired composition. The wires are fed into the weld simultaneously. The relative feed rates of the wires and the wire diameters determine the weld deposit composition.

Nano-Structured Bio-Inorganic Hybrid Material for High Performing Oxygen Reduction Catalyst.

PubMed

Jiang, Rongzhong; Tran, Dat T; McClure, Joshua P; Chu, Deryn

2015-08-26

In this study, we demonstrate a non-Pt nanostructured bioinorganic hybrid (BIH) catalyst for catalytic oxygen reduction in alkaline media. This catalyst was synthesized through biomaterial hemin, nanostructured Ag-Co alloy, and graphene nano platelets (GNP) by heat-treatment and ultrasonically processing. This hybrid catalyst has the advantages of the combined features of these bio and inorganic materials. A 10-fold improvement in catalytic activity (at 0.8 V vs RHE) is achieved in comparison of pure Ag nanoparticles (20-40 nm). The hybrid catalyst reaches 80% activity (at 0.8 V vs RHE) of the state-of-the-art catalyst (containing 40% Pt and 60% active carbon). Comparable catalytic stability for the hybrid catalyst with the Pt catalyst is observed by chronoamperometric experiment. The hybrid catalyst catalyzes 4-electron oxygen reduction to produce water with fast kinetic rate. The rate constant obtained from the hybrid catalyst (at 0.6 V vs RHE) is 4 times higher than that of pure Ag/GNP catalyst. A catalytic model is proposed to explain the oxygen reduction reaction at the BIH catalyst.

Wire chamber

DOEpatents

Atac, Muzaffer

1989-01-01

A wire chamber or proportional counter device, such as Geiger-Mueller tube or drift chamber, improved with a gas mixture providing a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor.

Weld Wire Investigation Summary

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

Cunningham, M.A.

1999-03-22

After GTA welding reservoir A production/process prove-in assemblies, X-ray examination detected a lack of sidewall fusion. After examining several possible causes, it was determined that the weld wire filler metal was responsible, particularly the wire cleaning process. The final conclusion was that the filler wire must be abrasively cleaned in a particular manner to perform as required. The abrasive process was incorporated into the wire material specification, ensuring consistency for all reservoir GTA welding at AlliedSignal Federal Manufacturing and Technologies (FM and T).

30 CFR 75.906 - Trailing cables for mobile equipment, ground wires, and ground check wires.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Trailing cables for mobile equipment, ground wires, and ground check wires. 75.906 Section 75.906 Mineral Resources MINE SAFETY AND HEALTH..., ground wires, and ground check wires. [Statutory Provisions] Trailing cables for mobile equipment shall...

30 CFR 75.906 - Trailing cables for mobile equipment, ground wires, and ground check wires.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Trailing cables for mobile equipment, ground wires, and ground check wires. 75.906 Section 75.906 Mineral Resources MINE SAFETY AND HEALTH..., ground wires, and ground check wires. [Statutory Provisions] Trailing cables for mobile equipment shall...

Superconducting wire manufactured

NASA Astrophysics Data System (ADS)

Fu, Yuexian; Sun, Yue; Xu, Shiming; Peng, Ying

1985-10-01

The MF Nb/Cu Extrusion Tube Method was used to manufacture 3 kg of stable practical MF Nb2Sn composite superconducting wire containing pure Cu(RRR approx. 200)/Ta. The draw state composite wire diameter was 0.56 mm, it contained 11,448 x 2.6 micron Nb core, and the twist distance was 1.5 cm. The composite wire cross-section was pure Cu/Ta/11,448 Nb core/Cu/ 91Sn-Cu; containing 22.8 v. % pure Cu, 13.3 v. % Ta; within the Ta layer to prevent Sn diffusion. The wire was sheathed in nonalkaline glass fiber as an insulating layer. A section of wire weighing 160 g was cut off and coiled it into a small solenoid. After reaction diffusion processing at 675 C/30 and curing by vacuum dipping in paraffin, it was measured in a Nb-Ti backfield of 7.2 T intensity, a current of 129 A was passed through the Nb3Sn solenoid and produced a strength of 2.5 T, the overall magnetic field intensity of the composite magnet reached 9.7 T. At this time, the wire full current density J sub c.w. = 5.2 x 10 to the 4th power A/sq cm; the effective current density J sub c (Nb + Sn - Cu) = 8.2 x 10 to the 4th power A/sq cm.

Using wire shaping techniques and holographic optics to optimize deposition characteristics in wire-based laser cladding.

PubMed

Goffin, N J; Higginson, R L; Tyrer, J R

2016-12-01

In laser cladding, the potential benefits of wire feeding are considerable. Typical problems with the use of powder, such as gas entrapment, sub-100% material density and low deposition rate are all avoided with the use of wire. However, the use of a powder-based source material is the industry standard, with wire-based deposition generally regarded as an academic curiosity. This is because, although wire-based methods have been shown to be capable of superior quality results, the wire-based process is more difficult to control. In this work, the potential for wire shaping techniques, combined with existing holographic optical element knowledge, is investigated in order to further improve the processing characteristics. Experiments with pre-placed wire showed the ability of shaped wire to provide uniformity of wire melting compared with standard round wire, giving reduced power density requirements and superior control of clad track dilution. When feeding with flat wire, the resulting clad tracks showed a greater level of quality consistency and became less sensitive to alterations in processing conditions. In addition, a 22% increase in deposition rate was achieved. Stacking of multiple layers demonstrated the ability to create fully dense, three-dimensional structures, with directional metallurgical grain growth and uniform chemical structure.

Using wire shaping techniques and holographic optics to optimize deposition characteristics in wire-based laser cladding

PubMed Central

Higginson, R. L.; Tyrer, J. R.

2016-01-01

In laser cladding, the potential benefits of wire feeding are considerable. Typical problems with the use of powder, such as gas entrapment, sub-100% material density and low deposition rate are all avoided with the use of wire. However, the use of a powder-based source material is the industry standard, with wire-based deposition generally regarded as an academic curiosity. This is because, although wire-based methods have been shown to be capable of superior quality results, the wire-based process is more difficult to control. In this work, the potential for wire shaping techniques, combined with existing holographic optical element knowledge, is investigated in order to further improve the processing characteristics. Experiments with pre-placed wire showed the ability of shaped wire to provide uniformity of wire melting compared with standard round wire, giving reduced power density requirements and superior control of clad track dilution. When feeding with flat wire, the resulting clad tracks showed a greater level of quality consistency and became less sensitive to alterations in processing conditions. In addition, a 22% increase in deposition rate was achieved. Stacking of multiple layers demonstrated the ability to create fully dense, three-dimensional structures, with directional metallurgical grain growth and uniform chemical structure. PMID:28119550

Hydrogen in Mono-Atomic Gold Wires

NASA Astrophysics Data System (ADS)

Barnett, Robert N.; Sherbakov, Andrew G.; Landman, Uzi; Hakkinen, Hannu

2004-03-01

Results of ab-initio scalar relativistic density functional calculations of the interaction between a mono-atomic gold wire (suspended between two gold tips) and a hydrogen molecule, at various stages of wire stretching, are presented. The hydrogen molecule does not bind to the wire until the wire is sufficiently stretched, i.e. starting to break, at which time the molecule inserts itself into the wire restoring a fraction of the conductance quantum g. With subsequent compression of the wire the axis of the molecule gradually tips away from the wire axis until it becomes "quasi-dissociated" with the H-H axis perpendicular to the wire. At this point the conductance almost vanishes, while for the bare wire the conductance at this tip-to-tip separation is close to 1g. These results, and the frequency of various vibrational modes of the hydrogen molecule, are compared with recent experimental and theoretical work involving platinum wires.

1 mil gold bond wire study.

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

Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.

2013-05-01

In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, themore » gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.« less

Corrosion of Wires on Wooden Wire-Bound Packaging Crates

Treesearch

Samuel L. Zelinka; Stan Lebow

2015-01-01

Wire-bound packaging crates are used by the US Army to transport materials. Because these crates may be exposed to harsh environments, they are dip-treated with a wood preservative (biocide treatment). For many years, zinc-naphthenate was the most commonly used preservative for these packaging crates and few corrosion problems with the wires were observed. Recently,...

Ag-Cu mixed phase plasmonic nanostructures fabricated by shadow nanosphere lithography and glancing angle co-deposition

NASA Astrophysics Data System (ADS)

Ingram, Whitney; Larson, Steven; Carlson, Daniel; Zhao, Yiping

2017-01-01

By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory. All compositions of the nanopattern had the same shape, but showed tunable localized surface plasmon resonance (LSPR) properties. In general, the LSPR of the nanopatterns redshifted with decreasing composition. Such a relation could be fitted by an empirical model based on the bulk theory of alloy plasmonics. By changing the colloidal template and the material deposited, this fabrication technique can be used to produce other alloy plasmonic nanostructures with predicted LSPR wavelengths.

Ag-Cu mixed phase plasmonic nanostructures fabricated by shadow nanosphere lithography and glancing angle co-deposition.

PubMed

Ingram, Whitney; Larson, Steven; Carlson, Daniel; Zhao, Yiping

2017-01-06

By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory. All compositions of the nanopattern had the same shape, but showed tunable localized surface plasmon resonance (LSPR) properties. In general, the LSPR of the nanopatterns redshifted with decreasing composition. Such a relation could be fitted by an empirical model based on the bulk theory of alloy plasmonics. By changing the colloidal template and the material deposited, this fabrication technique can be used to produce other alloy plasmonic nanostructures with predicted LSPR wavelengths.

Morphological, Structural and Optical Evolution of Ag Nanostructures on c-Plane GaN Through the Variation of Deposition Amount and Temperature

NASA Astrophysics Data System (ADS)

Sui, Mao; Li, Ming-Yu; Pandey, Puran; Zhang, Quanzhen; Kunwar, Sundar; Lee, Jihoon

2018-03-01

Owing to their tunable properties, Ag nanostructures have been widely adapted in various applications and the morphological control can determine their performance and effectiveness. In this work, we demonstrate the morphological and optical evolution of Ag nanostructures on GaN (0001) by the systematic control of deposition amount at two distinctive annealing temperatures. Based on the Volmer-Weber and coalescence growth models, the nanostructure growth commenced by the thermal solid-state-dewetting evolve in terms of size, density and configuration. At 450 °C, the round-dome shaped Ag nanoparticles (regime I), irregular Ag nano-mounds (regime II) and void-layer structures (regime III) are observed along with the gradually increased deposition amount. As a sharp distinction, the solid state dewetting process occur more radically at 700 °C and also, the Ag sublimation and the effect on the nanostructure formation are observed in a clear regime shift scaled by the deposition amount. Meanwhile, a strong dependency of reflectance spectra evolution on the Ag nanostructure morphology is witnessed for both sets. In particular, Ag dipolar resonance peaks are significantly red-shifted from VIS to NIR regions along with the nanostructure evolution. The reflectance, PL and Raman intensity variation are also observed and discussed based on the evolution of Ag nanostructures.

Influence of bolt tightening torque, wire size, and component reuse on wire fixation in circular external fixation.

PubMed

Wosar, Marc A; Marcellin-Little, Denis J; Roe, Simon C

2002-01-01

To evaluate the effects of bolt torque, wire size, and component reuse on the ability to maintain wire tension in 3 external skeletal fixation systems. Biomechanical study. Yield strength in tension of 1.0-, 1.2-, 1.5-, and 1.6-mm-diameter wires, and yield strength in torque of Hofmann Small Bone Fixation (SBF) cannulated and slotted bolts and IMEX regular and miniature bolts were determined on a testing machine. The minimum bolt tightening torque needed to prevent wire slippage at clinically recommended wire tensions was determined. Components were tested 10 times, and loads at slippage were recorded. The IMEX system required a mean of 8 Nm of bolt tightening torque to maintain 900 N (1.6-mm wires). The SBF system required a mean of 3 Nm bolt torque to maintain 300 N (1.0-mm wires) and 5 Nm to maintain 600 N (1.2-mm wires). The SBF cannulated bolt required 9 Nm of torque to maintain 900 N (1.5-mm wires). The SBF slotted bolts could only maintain 800 N before yield. The IMEX miniature system required a mean bolt torque of 1.1 Nm to maintain 300 N. The cannulated and slotted bolts from both manufacturers failed to maintain 70% of initial wire tension after 7 and 4 uses, respectively. The IMEX systems and the SBF system using 1.0- and 1.2-mm wires could maintain clinically recommended wire tension safely. Only the IMEX system could maintain clinically recommended wire tension safely using 1.5- or 1.6-mm wires. The SBF system using 1.0- and 1.2-mm wires and the IMEX system using all wire sizes can maintain clinically relevant wire tension. The SBF system using 1.5-mm wires could not. Cannulated and slotted bolts should not be used more than 6 and 3 times, respectively. Nuts should not be reused. Copyright 2002 by The American College of Veterinary Surgeons

Deformation processed Al/Ca nano-filamentary composite conductors for HVDC applications

NASA Astrophysics Data System (ADS)

Czahor, C. F.; Anderson, I. E.; Riedemann, T. M.; Russell, A. M.

2017-07-01

Efficient long-distance power transmission is necessary as the world continues to implement renewable energy sources, often sited in remote areas. Light, strong, high-conductivity materials are desirable for this application to reduce both construction and operational costs. In this study an Al/Ca (11.5% vol.) composite with nano-filamentary reinforcement was produced by powder metallurgy then extruded, swaged, and wire drawn to a maximum true strain of 12.7. The tensile strength increased exponentially as the filament size was reduced to the sub-micron level. In an effort to improve the conductor’s ability to operate at elevated temperatures, the deformation-processed wires were heat-treated at 260°C to transform the Ca-reinforcing filaments to Al2Ca. Such a transformation raised the tensile strength by as much as 28%, and caused little change in ductility, while the electrical conductivity was reduced by only 1% to 3%. Al/Al2Ca composites are compared to existing conductor materials to show how implementation could affect installation and performance.

Nanoscale characterization of 1D Sn-3.5Ag nanosolders and their application into nanowelding at the nanoscale

NASA Astrophysics Data System (ADS)

Zhang, Hong; Zhang, Junwei; Lan, Qianqian; Ma, Hongbin; Qu, Ke; Inkson, Beverley J.; Mellors, Nigel J.; Xue, Desheng; Peng, Yong

2014-10-01

One-dimensional Sn-3.5Ag alloy nanosolders have been successfully fabricated by a dc electrodeposition technique into nanoporous templates, and their soldering quality has been demonstrated in nanoscale electrical welding for the first time, which indicates that they can easily form remarkably reliable conductive joints. The electrical measurement shows that individual 1D Sn-3.5Ag nanosolders have a resistivity of 28.9 μΩ·cm. The morphology, crystal structure and chemistry of these nanosolders have been characterized at the nanoscale. It is found that individual 1D Sn-3.5Ag alloy nanosolders have a continuous morphology and smooth surface. XPS confirms the presence of tin and silver with a mass ratio of 96.54:3.46, and EDX elemental mappings clearly reveal that the Sn and Ag elements have a uniform distribution. Coveragent beam electron diffractions verify that the crystal phases of individual 1D Sn-3.5Ag alloy nanosolders consist of matrix β-Sn and the intermetallic compound Ag3Sn. The reflow experiments reveal that the eutectic composition of the 1D Sn-Ag alloy nanowire is shifted to the Sn rich corner. This work may contribute one of the most important tin-based alloy nanosolders for future nanoscale welding techniques, which are believed to have broad applications in nanotechnology and the future nano-industry.

Effect of nano-packing on preservation quality of fresh strawberry (Fragaria ananassa Duch. cv Fengxiang) during storage at 4 degrees C.

PubMed

Yang, F M; Li, H M; Li, F; Xin, Z H; Zhao, L Y; Zheng, Y H; Hu, Q H

2010-04-01

A novel nano-packing material with lower relative humidity, oxygen transmission rate and high longitudinal strength was synthesized by blending polyethylene with nano-powder (nano-Ag, kaolin, anatase TiO(2), rutile TiO(2)), and its effect on preservation quality of strawberry fruits (Fragaria ananassa Duch. cv Fengxiang) was investigated during storage at 4 degrees C. Results showed that nano-packaging was able to maintain the sensory, physicochemical, and physiological quality of strawberry fruits at a higher level compared with the normal packing (polyethylene bags). After a 12-d storage, decreases in the contents of total soluble solids, titratable acidity, and ascorbic acid of nano-packing were significantly inhibited. Meanwhile, decay rate, anthocyanin, and malondialdehyde contents were decreased to 16.7%, 26.3 mg/100g, 66.3 micromol/g for nano-packing and 26.8%, 31.9 mg/100g, 75.4 micromol/g for normal packing; polyphenoloxidase (PPO) and pyrogallol peroxidase (POD) activities were significantly lower in nano-packing than the control. These data indicated that the nano-packaging might provide an attractive alternative to improve preservation quality of the strawberry fruits during extended storage. Nano-packing exhibited identified quality benefits applicable to the preservation of fresh strawberry. Furthermore, nano-packing has the advantages of simple processing and feasibility to be industrialized in contrast with other storages. Thus, the utilization of nano-packing will likely assist commercial producers and retailers in extending the shelf life of products over a broader range in the future.

Controlled assembly of silver nano-fluid in Heliotropium crispum extract: A potent anti-biofilm and bactericidal formulation

NASA Astrophysics Data System (ADS)

Khan, Faria; Hashmi, Muhammad Uzair; Khalid, Nauman; Hayat, Muhammad Qasim; Ikram, Aamer; Janjua, Hussnain A.

2016-11-01

The study describes the optimized method for silver nanoparticle (AgNPs) synthesis using Heliotropium crispum (HC) plant extract. Optimization of physicochemical parameters resulted in stable and rapidly assembled AgNPs. FTIR results suggest presence of plant phytochemicals that helped in the reduction, stabilization and capping of AgNPs. The assembled Ag nano-composites displayed the peak surface plasmon resonance (SPR) around 428 nm. The presence of uniquely assembled Ag-biomolecule composites, cap and stabilize nanoparticles in aqueous plant suspension. Spherical, uniform-shaped AgNPs with low poly-dispersion and average particle size of 42 nm and was determined through dynamic light scattering (DLS) and scanning election microscopy (SEM) which present robust interaction with microbes. The study also evaluates the antimicrobial and anti-biofilm properties of biologically synthesized AgNPs on clinical isolates of MRSA, Pseudomonas aeruginosa and Acinetobacter baumannii. Minimum inhibitory concentration (0.5 mg mL-1) of nanoparticles that presented bactericidal effect was made through inhibition assays on bacterial strains. The concentration which presented potent bactericidal response was then evaluated through growth inhibition in liquid medium for anti-biofilm studies at 2.0 mg mL-1. HC-Ag nanoparticles mediated anti-biofilm effects on Pseudomonas aeruginosa was revealed through SEM. Complete breakdown of biofilm's extracellular polymeric substances resulted after incubation with AgNPs. Peptidoglycan cell wall destruction was also revealed on planktonic bacterial images after 24 h of incubation.

49 CFR 234.231 - Fouling wires.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Fouling wires. 234.231 Section 234.231..., Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway... single duplex wire with single plug acting as fouling wires is prohibited. Existing installations having...

49 CFR 234.231 - Fouling wires.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Fouling wires. 234.231 Section 234.231..., Inspection, and Testing Maintenance Standards § 234.231 Fouling wires. Each set of fouling wires in a highway... single duplex wire with single plug acting as fouling wires is prohibited. Existing installations having...

Effects of dispersible MoS2 nanosheets and Nano-silver coexistence on the metabolome of yeast.

PubMed

Yang, Qi; Zhang, Lei; Ben, Ailing; Wu, Na; Yi, Yanliang; Jiang, Ling; Huang, He; Yu, Yadong

2018-05-01

As a new rising star in the post-graphene two-dimensional materials (2DMs), molybdenum disulfide (MoS 2 ) attracts increasing attentions and is widely applied. However, the chemical and toxicological interaction between MoS 2 and other co-contaminants is still poorly understood. Nano-silver (N-Ag) is the most commonly used nanomaterial in commercial products and distributed widely in the environment. Herein, we investigated the effects of chitosan functionalized MoS 2 (CS-MoS 2 ) nanosheets, a water-dispersible form of MoS 2 , on the microbial toxicity of N-Ag. We found that the incorporation of CS-MoS 2 nanosheets attenuated the oxidative stress induced by N-Ag on yeast cells, while caused more membrane stress. In addition, the inhibition of N-Ag on the metabolic activities of yeast cells could be attenuated by CS-MoS 2 nanosheets as well. The coexistence of N-Ag and CS-MoS 2 nanosheets mainly perturbed the amino acid-related metabolic pathways in yeast cells, and phosphoric acid was a potential nanotoxicity biomarker. We further found that CS-MoS 2 nanosheets dramatically absorbed the Ag ion released from N-Ag, which might be responsible for its attenuation effect on the microbial toxicity of N-Ag. Our findings provide more new insights for the ecotoxicity evaluation of MoS 2 and other 2DMs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Improvement in current density of nano- and micro-structured Si solar cells by cost-effective elastomeric stamp process

NASA Astrophysics Data System (ADS)

Jeon, Kiseok; Jee, Hongsub; Lim, Sangwoo; Park, Min Joon; Jeong, Chaehwan

2018-03-01

Effective incident light should be controlled for improving the current density of solar cells by employing nano- and micro-structures on silicon surface. The elastomeric stamp process, which is more cost effective and simpler than conventional photolithography, was proposed for the fabrication of nano- and micro-structures. Polydimethylsiloxane (PDMS) was poured on a mother pattern with a diameter of 6 μm and a spacing of 2 μm; then, curing was performed to create a PDMS mold. The regular micropattern was stamped on a low-viscosity resin-coated silicon surface, followed by the simple reactive ion etching process. Nano-structures were formed using the Ag-based electroless etching process. As etching time was increased to 6 min, reflectance decreased to 4.53% and current density improved from 22.35 to 34.72 mA/cm2.

Characterization and Influence of Green Synthesis of Nano-Sized Zinc Complex with 5-Aminolevulinic Acid on Bioactive Compounds of Aniseed.

PubMed

Tavallali, Vahid; Rahmati, Sadegh; Rowshan, Vahid

2017-11-01

A new water soluble zinc-aminolevulinic acid nano complex (n[Zn(ALA) 2 ]), which was characterized by TEM, IR, and EDX spectra, has been prepared via sonochemical method under green conditions in water. In the current study, the effectiveness of foliar Zn amendment using synthetic Zn-ALA nano complex, as a new introduced Zn-fertilizer here, was evaluated. As the model plant, Pimpinella anisum, the most valuable spice and medicinal plant grown in warm regions, was used. By using zinc nano complex, further twenty compounds were obtained in the essential oil of anise plants. Application of 0.2% (w/v) Zn-ALA nano complex increased the levels of (E)-anethole, β-bisabolene, germacrene D, methyl chavicol, and α-zingiberene in the essential oil. Nano Zn complex at the rate of 0.2% induced considerable high phenolic compounds and zinc content of shoots and seeds. Chlorogenic acid had the highest level between four detected phenolic compounds. The maximum antioxidant activity was monitored through the application of Zn nano complex. According to the results, nanoscale nutrients can be provided with further decreased doses for medicinal plants. Using Zn-ALA nano complex is a new and efficient method to improve the pharmaceutical and food properties of anise plants. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Tailor-made Au@Ag core-shell nanoparticle 2D arrays on protein-coated graphene oxide with assembly enhanced antibacterial activity

NASA Astrophysics Data System (ADS)

Wang, Huiqiao; Liu, Jinbin; Wu, Xuan; Tong, Zhonghua; Deng, Zhaoxiang

2013-05-01

Water-dispersible two-dimensional (2D) assemblies of Au@Ag core-shell nanoparticles are obtained through a highly selective electroless silver deposition on pre-assembled gold nanoparticles on bovine serum albumin (BSA)-coated graphene oxide (BSA-GO). While neither BSA-GO nor AuNP-decorated BSA-GO shows any antibacterial ability, the silver-coated GO@Au nanosheets (namely GO@Au@Ag) exhibit an enhanced antibacterial activity against Gram-negative Escherichia coli (E. coli) bacteria, superior to unassembled Au@Ag nanoparticles and even ionic Ag. Such an improvement may be attributed to the increased local concentration of silver nanoparticles around a bacterium and a polyvalent interaction with the bacterial surface. In addition, the colloidal stability of this novel nano-antimicrobial against the formation of random nanoparticle aggregates guarantees a minimized activity loss of the Au@Ag nanoparticles. The antibacterial efficacy of GO@Au@Ag is less sensitive to the existence of Cl-, in comparison with silver ions, providing another advantage for wound dressing applications. Our research unambiguously reveals a strong and very specific interaction between the GO@Au@Ag nanoassembly and E. coli, which could be an important clue toward a rational design, synthesis and assembly of innovative and highly active antibacterial nanomaterials.

Apollo experience report: Electrical wiring subsystem

NASA Technical Reports Server (NTRS)

White, L. D.

1975-01-01

The general requirements of the electrical wiring subsystems and the problem areas and solutions that occurred during the major part of the Apollo Program are detailed in this report. The concepts and definitions of specific requirements for electrical wiring; wire-connecting devices; and wire-harness fabrication, checkout, and installation techniques are discussed. The design and development of electrical wiring and wire-connecting devices are described. Mission performance is discussed, and conclusions and recommendations for future programs are presented.

Forming Refractory Insulation On Copper Wire

NASA Technical Reports Server (NTRS)

Setlock, J.; Roberts, G.

1995-01-01

Alternative insulating process forms flexible coat of uncured refractory insulating material on copper wire. Coated wire formed into coil or other complex shape. Wire-coating apparatus forms "green" coat on copper wire. After wire coiled, heating converts "green" coat to refractory electrical insulator. When cured to final brittle form, insulating material withstands temperatures above melting temperature of wire. Process used to make coils for motors, solenoids, and other electrical devices to be operated at high temperatures.

As-synthesis of nanostructure AgCl/Ag/MCM-41 composite

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Pourahmad, A.

2012-02-01

In this work, we present the simple synthetic route for silver chloride/silver nanoparticles (AgCl/Ag-NPs) using as-synthesis method. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed that when AgNO 3 content is below 0.1 wt.% in synthetic gel, the guest AgCl/Ag-NPs is formed on the silica channel wall, and lower exists in the crystalline state. When AgNO 3 content exceeds this value, AgCl/Ag nanoparticles can be observed in high crystalline state. The absorption at 327 nm ascribed to the characteristic absorption of the AgCl semiconductor. Ag nanoparticles have been shown to exist in the nanocomposite at 375 nm. When AgNO 3 content is above 0.1 wt.% in synthetic gel, spectra exhibited stronger absorption at 450-700 nm that was attributed to the surface plasmonic resonance of silver nanoparticles. The obtained AgCl/Ag/MCM-41 sample exhibit enhanced photocatalytic activity for the degradation of methylene blue under visible-light irradiation.

Manually Operated Welding Wire Feeder

NASA Technical Reports Server (NTRS)

Rybicki, Daniel J. (Inventor)

2001-01-01

A manual welding wire feeder apparatus comprising a bendable elongate metal frame with a feed roller mounted at the center thereof for rotation about an axis transverse to the longitudinal axis of the frame. The frame ends are turned up as tabs and each provided with openings in alignment with each other and the mid-width center of the roller surface. The tab openings are sized to accommodate welding wire and each extends to a side edge of the tab, both opening on the same side of the frame, whereby welding wire can be side-loaded onto the frame. On the side of the frame, opposite the roller a lock ring handle is attached tangentially and is rotatable about the attachment point and an axis perpendicular to the frame. The device is grasped in the hand normally used to hold the wire. A finger is placed through the loop ring and the frame positioned across the palm and lower fingers. The thumb is positioned atop the wire so it can be moved from the back of the frame across the roller, and towards the front. In doing so, the wire is advanced at a steady rate in axial alignment with the tab openings and roller. To accommodate different wire diameters the frame is bendable about its center in the plane of the frame axis and wire so as to keep the wire in sufficient tension against the roller and to keep the wire fixed when the frame is tilted and thumb pressure released.

Electrode carrying wire for GTAW welding

NASA Technical Reports Server (NTRS)

Morgan, Gene E. (Inventor); Dyer, Gerald E. (Inventor)

1990-01-01

A welding torch for gas tungsten arc welding apparatus has a hollow tungsten electrode including a ceramic liner and forms the filler metal wire guide. The wire is fed through the tungsten electrode thereby reducing the size of the torch to eliminate clearance problems which exist with external wire guides. Since the wire is preheated from the tungsten more wire may be fed into the weld puddle, and the wire will not oxidize because it is always within the shielding gas.

Internal wire guide for GTAW welding

NASA Technical Reports Server (NTRS)

Morgan, Gene E. (Inventor); Dyer, Gerald E. (Inventor)

1989-01-01

A welding torch for gas tungsten arc welding apparatus has a filler metal wire guide positioned within the torch, and within the shielding gas nozzle. The wire guide is adjacent to the tungsten electrode and has a ceramic liner through which the wire is fed. This reduces the size of the torch and eliminates the outside clearance problems that exit with external wire guides. Additionally, since the wire is always within the shielding gas, oxidizing of the wire is eliminated.

Thermochemical properties of silver tellurides including empressite (AgTe) and phase diagrams for Ag-Te and Ag-Te-O

NASA Astrophysics Data System (ADS)

Voronin, Mikhail V.; Osadchii, Evgeniy G.; Brichkina, Ekaterina A.

2017-10-01

This study compiles original experimental and literature data on the thermodynamic properties (ΔfG°, S°, ΔfH°) of silver tellurides (α-Ag2Te, β-Ag2Te, Ag1.9Te, Ag5Te3, AgTe) obtained by the method of solid-state galvanic cell with the RbAg4I5 and AgI solid electrolytes. The thermodynamic data for empressite (AgTe, pure fraction from Empress Josephine Mine, Colorado USA) have been obtained for the first time by the electrochemical experiment with the virtual reaction Ag + Te = AgTe. The Ag-Te phase diagrams in the T - x and log fTe2 (gas) - 1/ T coordinates have been refined, and the ternary Ag-Te-O diagrams with Ag-Te-TeO2 (paratellurite) composition range have been calculated.

E-beam deposited Ag-nanoparticles plasmonic organic solar cell and its absorption enhancement analysis using FDTD-based cylindrical nano-particle optical model.

PubMed

Kim, Richard S; Zhu, Jinfeng; Park, Jeung Hun; Li, Lu; Yu, Zhibin; Shen, Huajun; Xue, Mei; Wang, Kang L; Park, Gyechoon; Anderson, Timothy J; Pei, Qibing

2012-06-04

We report the plasmon-assisted photocurrent enhancement in Ag-nanoparticles (Ag-NPs) embedded PEDOT:PSS/P3HT:PCBM organic solar cells, and systematically investigate the causes of the improved optical absorption based on a cylindrical Ag-NPs optical model which is simulated with a 3-Dimensional finite difference time domain (FDTD) method. The proposed cylindrical Ag-NPs optical model is able to explain the optical absorption enhancement by the localized surface plasmon resonance (LSPR) modes, and to provide a further understanding of Ag-NPs shape parameters which play an important role to determine the broadband absorption phenomena in plasmonic organic solar cells. A significant increase in the power conversion efficiency (PCE) of the plasmonic solar cell was experimentally observed and compared with that of the solar cells without Ag-NPs. Finally, our conclusion was made after briefly discussing the electrical effects of the fabricated plasmonic organic solar cells.

Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

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

Singh, Anamika; Dutta, Dimple P., E-mail: dimpled@barc.gov.in; Ballal, A.

Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed thatmore » inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.« less

49 CFR 234.239 - Tagging of wires and interference of wires or tags with signal apparatus.

Code of Federal Regulations, 2011 CFR

2011-10-01

... with signal apparatus. 234.239 Section 234.239 Transportation Other Regulations Relating to... Tagging of wires and interference of wires or tags with signal apparatus. Each wire shall be tagged or... of the apparatus. This requirement applies to each wire at each terminal in all housings including...

49 CFR 234.239 - Tagging of wires and interference of wires or tags with signal apparatus.

Code of Federal Regulations, 2010 CFR

2010-10-01

... with signal apparatus. 234.239 Section 234.239 Transportation Other Regulations Relating to... Tagging of wires and interference of wires or tags with signal apparatus. Each wire shall be tagged or... of the apparatus. This requirement applies to each wire at each terminal in all housings including...

A new tubular hot-wire CVD for diamond coating

NASA Astrophysics Data System (ADS)

Motahari, Hamid; Bellah, Samad Moemen; Malekfar, Rasoul

2017-06-01

A new tubular hot-wire chemical vapor deposition (HWCVD) system using a tubular quartz vacuum chamber has been fabricated. The filaments in this system can heat the substrate and act as a gas activator and thermally activator for gas species at the same time. The nano- and microcrystalline diamond coatings on the surface of steel AISI 316 substrates have been grown. To assess the results, SEM and FESEM images and Raman spectroscopy investigations have been applied. The results reveal that micro- and nanocrystalline diamond structures have been formed in the coatings, but the disordered diamond and some non-diamond phases, such as graphitic carbons, are also present in the coating layers. The analytical measurements show the growth of diamond films with well-faceted crystals in (111) direction. However, intrinsic stress, secondary nucleation, and poor adhesion are the main issues of future research for this new designed HWCVD.

Fabrication of nano-silver particles using Cymodocea serrulata and its cytotoxicity effect against human lung cancer A549 cells line

NASA Astrophysics Data System (ADS)

Palaniappan, P.; Sathishkumar, G.; Sankar, R.

2015-03-01

The present study reports, green synthesis of bioactive silver nanoparticles (AgNPs) under different temperature (60 °C, room temperature and 4° refrigerator) using the aqueous extract of sea grass Cymodocea serrulata as a potential bioreductant. Increased temperature fabricates more AgNPs compare to room temperature and refrigerator condition. At first the reduction of Ag+ ions were confirmed through color change which produces an absorbance spectra at 420 nm in UV-Visible spectrophotometer. Additionally various exclusive instrumentations such as X-ray diffraction (XRD), Dynamic light scattering (DLS), scanning electron microscope (SEM) analysis and Transmission electron microscope (TEM) were authorizes the biosynthesis and physio-chemical characterization of AgNPs. From Fourier transform infrared spectroscopy (FTIR) analysis, it was identified that the water soluble fractions of the sea grass mainly responsible for reduction of ionic silver (Ag+) into (Ag0) nano-ranged particles and also they act as stabilizing agent to sustain the durability of NPs for long period of time. Further, synthesized AgNPs shows potential cytotoxicity against human lung cancer A549 cells (LD50-100 μg/ml). The overall results suggest that C. serrulata is a valuable bioresource to generate rapid and eco-friendly bioactive AgNPs towards cancer therapy.

Inhibitory effect of super-hydrophobicity on silver release and antibacterial properties of super-hydrophobic Ag/TiO2 nanotubes.

PubMed

Zhang, Licheng; Zhang, Lihai; Yang, Yun; Zhang, Wei; Lv, Houchen; Yang, Fei; Lin, Changjian; Tang, Peifu

2016-07-01

The antibacterial properties of super-hydrophobic silver (Ag) on implant surface have not yet to be fully illuminated. In our study, we investigate the protective effects of super-hydrophobic coating of silver/titanium dioxide (Ag/TiO2 ) nanotubes against bacterial pathogens, as well as its pattern of Ag release. Ag/TiO2 nanotubes are prepared by a combination of electrochemical anodization and pulse electrodeposition. The super-hydrophobic coating is prepared by modifying the surface of Ag/TiO2 nanotubes with 1H, 1H, 2H, 2H-perfluorooctyl-triethoxysilane (PTES). Surface features and Ag release are examined by SEM, X-ray photoelectron spectroscopy, contact-angle measurement, and inductively coupled plasma-mass spectrometry (ICP-MS). The antibacterial activity of super-hydrophobic coating Ag/TiO2 nanotubes is investigated both in vitro and in vivo. Consequently, the super-hydrophobic coating on Ag/TiO2 nanotubes shows a regularly arranged structure; and nano-Ag particles (10-30 nm) are evenly distributed on the surface or inside the nanotubes. The contact angles of water on the super-hydrophobic coating Ag/TiO2 nanotubes are all above 150°. In addition, the super-hydrophobic character displays a certain conserved effect that contributes to the sustained release of Ag. The super-hydrophobic Ag/TiO2 nanotubes are also effective in inhibiting bacterial adhesion, killing the adhering bacteria and preventing postoperative infection in rabbits. Therefore, it is expected that the super-hydrophobic Ag/TiO2 nanotubes which can contain the release of Ag, leading to stable release, may show a consistent surface antibacterial capability. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1004-1012, 2016. © 2015 Wiley Periodicals, Inc.

Cavitation during wire brushing

NASA Astrophysics Data System (ADS)

Li, Bo; Zou, Jun; Ji, Chen

2016-11-01

In our daily life, brush is often used to scrub the surface of objects, for example, teeth, pots, shoes, pool, etc. And cleaning rust and stripping paint are accomplished using wire brush. Wire brushes also can be used to clean the teeth for large animals, such as horses, crocodiles. By observing brushing process in water, we capture the cavitation phenomenon on the track of moving brush wire. It shows that the cavitation also can affect the surface. In order to take clear and entire pictures of cavity, a simplified model of one stainless steel wire brushing a boss is adopted in our experiment. A transparent organic tank filled with deionized water is used as a view box. And a high speed video camera is used to record the sequences. In experiment, ambient pressure is atmospheric pressure and deionized water temperature is kept at home temperature. An obvious beautiful flabellate cavity zone appears behind the moving steel wire. The fluctuation of pressure near cavity is recorded by a hydrophone. More movies and pictures are used to show the behaviors of cavitation bubble following a restoring wire. Beautiful tracking cavitation bubble cluster is captured and recorded to show.

Wire-number effects on high-power annular z-pinches and some characteristics at high wire number

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

SANFORD,THOMAS W. L.

2000-05-23

Characteristics of annular wire-array z-pinches as a function of wire number and at high wire number are reviewed. The data, taken primarily using aluminum wires on Saturn are comprehensive. The experiments have provided important insights into the features of wire-array dynamics critical for high x-ray power generation, and have initiated a renaissance in z-pinches when high numbers of wires are used. In this regime, for example, radiation environments characteristic of those encountered during the early pulses required for indirect-drive ICF ignition on the NIF have been produced in hohlraums driven by x-rays from a z-pinch, and are commented on here.

[Separate vertical wiring combined with tension band and Kirschner-wire plus cerclage wire in the treatment of displaced inferior pole fractures of the patella].

PubMed

Zhang, J; Jiang, X Y; Huang, X W

2016-06-18

To investigate the clinical efficacy and outcomes of two separate vertical wiring combined with tension band and Kirschner-wire plus cerclage wire in the treatment of displaced inferior pole fractures of the patella. From January 2013 to January 2015, 15 consecutive patients (mean age 54.5 years) with inferior pole fractures of the patella were retrospectively included in this study. All the patients underwent open reduction and internal fixation by separate vertical wiring combined with tension band and Kirschner-wire plus cerclage wire through longitudinal incision, 4.5 d (range: 3.1-5.9 d) after initial injury. A safety check for early knee range of motion was performed before wound closure. The complications including infection, nonunion, loss of fixation and any wire breakage or irritation from implant were recorded. Anteroposterior and lateral views of the knee joint obtained during the follow-up were used to assess bony union based on the time when the fracture line disappeared. At the time of the final outpatient follow up, functional evaluation of the knee joint was conducted by Bostman system. The follow-up time was 13.1 months (range: 12-19 months) after surgery on average, immediate motion without immobilization in all the cases was allowed and there was no case of reduction loss of the fracture and wire breakage. There was no case of irritation from the implant. At the final follow-up, the average range of motion (ROM) arc was 126.7° (range: 115°-140°), the average ROM lag versus contralateral healthy leg was 10.3° (range: 0°-35°). The mean Bostman score at the last follow-up was 28.9 (range: 27-30), and graded excellent in most cases. Two separate vertical wiring is an easy and effective method to reduce the displaced inferior pole fracture of patella. Augmentation of separate vertical wiring with tension band and Kirschner-wire plus cerclage wire in these patients provides enough strength to protected the early exercise of the knee joint and

Surface-enhanced Raman scattering of a Ag/oligo(phenyleneethynylene)/Ag sandwich.

PubMed

Fletcher, Melissa; Alexson, D M; Prokes, Sharka; Glembocki, Orest; Vivoni, Alberto; Hosten, Charles

2011-02-01

α,ω-Dithiols are a useful class of compounds in molecular electronics because of their ability to easily adsorb to two metal surfaces, producing a molecular junction. We have prepared Ag nanosphere/oligo(phenyleneethynylene)/Ag sol (AgNS/OPE/Ag sol) and Ag nanowire/oligo(phenyleneethynylene)/Ag sol (AgNW/OPE/Ag sol) sandwiches to simulate the architecture of a molecular electronic device. This was achieved by self-assembly of OPE on the silver nanosurface, deprotection of the terminal sulfur, and deposition of Ag sol atop the monolayer. These sandwiches were then characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The resulting spectra were compared to the bulk spectrum of the dimer and to the Ag nanosurface/OPE SERS spectra. The intensities of the SERS spectra in both systems exhibit a strong dependence on Ag deposition time and the results are also suggestive of intense interparticle coupling of the electromagnetic fields in both the AgNW/OPE/Ag and the AgNS/OPE/Ag systems. Three previously unobserved bands (1219, 1234, 2037 cm(-1)) arose in the SER spectra of the sandwiches and their presence is attributed to the strong enhancement of the electromagnetic field which is predicted from the COSMOL computational package. The 544 cm(-1) disulfide bond which is observed in the spectrum of solid OPE but is absent in the AgNS/OPE/Ag and AgNW/OPE/Ag spectra is indicative of chemisorption of OPE to the nanoparticles through oxidative dissociation of the disulfide bond. Copyright © 2010 Elsevier B.V. All rights reserved.

Frequency response in short thermocouple wires

NASA Technical Reports Server (NTRS)

Forney, L. J.; Meeks, E. L.; Ma, J.; Fralick, G. C.

1992-01-01

Theoretical expressions are derived for the steady state frequency response of a thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for a nonuniform wire with unequal material properties and wire diameters across the junction. The amplitude ratio at low frequency omega approaches 0 agrees with the results of Scadron and Warshawsky (1952) for a steady state temperature distribution. Moreover, the frequency response for a nonuniform wire in the limit of infinite length l approaches infinity is shown to reduce to a simple expression that is analogous to the classic first order solution for a thermocouple wire with uniform properties. Theoretical expressions are also derived for the steady state frequency response of a supported thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a supported one material wire and a two material wire with unequal material properties across the junction. For the case of a one material supported wire, an exact solution is derived which compares favorably with an approximate expression that only matches temperatures at the support junction. Moreover, for the case of a two material supported wire, an analytical expression is derived that closely correlates numerical results. Experimental measurements are made for the steady state frequency response of a supported thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a supported one material wire (type K) and a two material wire (type T) with unequal material properties across the junction. The data for the amplitude ratio and phase angle are correlated to within 10 pct. with the theoretical predictions of Forney and Fralick (1991). This is accomplished by choosing a natural frequency omega sub n for the wire data to correlate the first order response at large gas temperature frequencies. It is found that a large bead size, however, will increase the amplitude ratio at

Novel AgNWs-PAN/TPU membrane for point-of-use drinking water electrochemical disinfection.

PubMed

Tan, Xiaojun; Chen, Chao; Hu, Yongyou; Wen, Junjie; Qin, Yanzhe; Cheng, Jianhua; Chen, Yuancai

2018-10-01

The safety of drinking water remains a major challenge in developing countries and point-of-use (POU) drinking water treatment device plays an important role in decentralised drinking water safety. In this study, a novel material, i.e. a silver nanowires-polyacrylonitrile/thermoplastic polyurethane (AgNWs-PAN/TPU) composite membrane, was fabricated via electrospinning and vacuum filtration deposition. Morphological and structural characterisation showed that the PAN/TPU fibres had uniform diameters and enhanced mechanical properties. When added to these fibres, the AgNWs formed a highly conductive network with good physical stability and low silver ion leaching (<100 ppb). A POU device equipped with a AgNWs-PAN/TPU membrane displayed complete removal of 10 5  CFU/mL bacteria, which were inactivated by silver ions released from the AgNWs within 6 h. Furthermore, under a voltage of 1.5 V, the bacteria were completely inactivated within 20-25 min. Inactivation efficiency in 5 mM NaCl solution was higher than those in Na 2 SO 4 and NaNO 3 solutions. We concluded that a strong electric field was formed at the AgNW tips. Additionally, silver ions and chlorine compounds worked synergistically in the disinfection process. This study provides a scientific basis for research and development of silver nanocomposite membranes, with high mechanical strength and high conductivity, for POU drinking water disinfection. Copyright © 2018 Elsevier B.V. All rights reserved.

Self-Catalyzed CdTe Wires.

PubMed

Baines, Tom; Papageorgiou, Giorgos; Hutter, Oliver S; Bowen, Leon; Durose, Ken; Major, Jonathan D

2018-04-25

CdTe wires have been fabricated via a catalyst free method using the industrially scalable physical vapor deposition technique close space sublimation. Wire growth was shown to be highly dependent on surface roughness and deposition pressure, with only low roughness surfaces being capable of producing wires. Growth of wires is highly (111) oriented and is inferred to occur via a vapor-solid-solid growth mechanism, wherein a CdTe seed particle acts to template the growth. Such seed particles are visible as wire caps and have been characterized via energy dispersive X-ray analysis to establish they are single phase CdTe, hence validating the self-catalysation route. Cathodoluminescence analysis demonstrates that CdTe wires exhibited a much lower level of recombination when compared to a planar CdTe film, which is highly beneficial for semiconductor applications.

Orbiter Kapton wire operational requirements and experience

NASA Technical Reports Server (NTRS)

Peterson, R. V.

1994-01-01

The agenda of this presentation includes the Orbiter wire selection requirements, the Orbiter wire usage, fabrication and test requirements, typical wiring installations, Kapton wire experience, NASA Kapton wire testing, summary, and backup data.

Moving Large Wiring-Harness Boards

NASA Technical Reports Server (NTRS)

Shepherd, Samuel D.; Gurman, Isaac

1990-01-01

Carrier for wiring-harness fabrication boards enables lone operator to move board easily and safely. Holds harness while operator fabricating, while being stored, and being transported to equipment frame for mounting. When positioned for assembly of wiring harness, board and carrier give operator easy and convenient access to wires and cables, when positioned for transfer of wiring harness to or from storage area, carrier holds board securely while moved by one person.

Wire EDM for Refractory Materials

NASA Technical Reports Server (NTRS)

Zellars, G. R.; Harris, F. E.; Lowell, C. E.; Pollman, W. M.; Rys, V. J.; Wills, R. J.

1982-01-01

In an attempt to reduce fabrication time and costs, Wire Electrical Discharge Machine (Wire EDM) method was investigated as tool for fabricating matched blade roots and disk slots. Eight high-strength nickel-base superalloys were used. Computer-controlled Wire EDM technique provided high quality surfaces with excellent dimensional tolerances. Wire EDM method offers potential for substantial reductions in fabrication costs for "hard to machine" alloys and electrically conductive materials in specific high-precision applications.

High strength, wire-reinforced electroformed structures

NASA Technical Reports Server (NTRS)

Kazaroff, J. M.; Duscha, R. A.; Mccandless, L. C.

1974-01-01

Using half-round reinforcing wires, electrodeposited matrix metal readily fills spaces between wires in intimate contact with wires and without voids. Procedure combines advantages of electroforming with high-strength of commonly available wire to produce non-welded shell structures for high pressure uses.

Cooperative infrared to visible upconversion and visible to near-infrared quantum cutting in Tb and Yb co-doped glass containing Ag nanoparticles

NASA Astrophysics Data System (ADS)

Pan, Z.; Sekar, G.; Akrobetu, R.; Mu, R.; Morgan, S. H.

2011-10-01

Tb, Yb, and Ag co-doped glass nano-composites were synthesized in a lithium-lanthanum-aluminosilicate glass matrix (LLAS) by a melt-quench technique. Ag nanoparticles (NPs) were formed in the glass matrix and confirmed by optical absorption and transmission electron microscopy (TEM). Plasmon enhanced luminescence was observed. Cooperative infrared to visible upconversion and visible to near-infrared quantum cutting were studied for samples with different thermal annealing times. Because the Yb3+ emission at 940 - 1020 nm is matched well with the band gap of crystalline Si, the quantum cutting effect may have its potential application in silicon-based solar cells.

Spring control of wire harness loops

NASA Technical Reports Server (NTRS)

Curcio, P. J.

1979-01-01

Negator spring control guides wire harness between movable and fixed structure. It prevents electrical wire harness loop from jamming or being severed as wire moves in response to changes in position of aircraft rudder. Spring-loaded coiled cable controls wire loop regardless of rudder movement.

Development of Novel Magnetic Metal Oxide Films and Carbon Nanotube Materials for Magnetic Device Applications

DTIC Science & Technology

2015-01-23

From these studies we learned that nano wires of Fe grown in the lumens of multi-walled carbon nanotubes ( MWCNTs ) required four times higher 35...studies we learned that nano wires of Fe grown in the lumens of multi-walled carbon nanotubes ( MWCNTs ) required four times higher magnetic field...properties of nano-metric Fe thin films on 325 MgO(100) and nano wires of Fe prepared in the lumens of MWCNTs using magnetron DC-sputtering were studied

Influence of varus/valgus positioning of the Nanos® and Metha® short-stemmed prostheses on stress shielding of metaphyseal bone.

PubMed

Brinkmann, V; Radetzki, F; Gutteck, N; Delank, S; Zeh, A

2017-03-01

The aim of this study was to analyze bone remodeling around the Nanos® (Smith & Nephew) and Metha® (Aesculap AG) implants as a function of varus/valgus stem positioning. In 75 patients with diagnosed coxarthrosis, either Nanos® (n= 51) or Metha® (n= 24) prostheses were implanted. Digital assessment of plain radiographs immediately, 97 days, and 381 days after THA showed no clinically-relevant migration, angulation, or change in offset and center of rotation. The DEXA scans showed significant BMD changes in Gruen zones 1 (-12.8%), 2 (-3.3%), 6 (+6.4%), and 7(-7.8%)(t-test). The pre/postoperative CCD for the Nanos® was 129°/ 135° and for the Metha® 131°/ 127°. Linear regression analysis showed no prediction for BMD by postoperative CCD or stem type. In conclusion, there was no clinically-relevant influence on proximal femur BMD according to varus/valgus implantation of the Nanos® or Metha® prostheses.

Raman Analysis of Dilute Aqueous Samples by Localized Evaporation of Submicroliter Droplets on the Tips of Superhydrophobic Copper Wires.

PubMed

Cheung, Melody; Lee, Wendy W Y; McCracken, John N; Larmour, Iain A; Brennan, Steven; Bell, Steven E J

2016-04-19

Raman analysis of dilute aqueous solutions is normally prevented by their low signal levels. A very general method to increase the concentration to detectable levels is to evaporate droplets of the sample to dryness, creating solid deposits which are then Raman probed. Here, superhydrophobic (SHP) wires with hydrophilic tips have been used as supports for drying droplets, which have the advantage that the residue is automatically deposited at the tip. The SHP wires were readily prepared in minutes using electroless galvanic deposition of Ag onto copper wires followed by modification with a polyfluorothiol (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decanethiol, HDFT). Cutting the coated wires with a scalpel revealed hydrophilic tips which could support droplets whose maximum size was determined by the wire diameter. Typically, 230 μm wires were used to support 0.6 μL droplets. Evaporation of dilute melamine droplets gave solid deposits which could be observed by scanning electron microscopy (SEM) and Raman spectroscopy. The limit of detection for melamine using a two stage evaporation procedure was 1 × 10(-6) mol dm(-3). The physical appearance of dried droplets of sucrose and glucose showed that the samples retained significant amounts of water, even under high vacuum. Nonetheless, the Raman detection limits of sucrose and glucose were 5 × 10(-4) and 2.5 × 10(-3) mol dm(-3), respectively, which is similar to the sensitivity reported for surface-enhanced Raman spectroscopy (SERS) detection of glucose. It was also possible to quantify the two sugars in mixtures at concentrations which were similar to those found in human blood through multivariate analysis.

DNA in the material world: electrical properties and nano-applications.

PubMed

Triberis, Georgios P; Dimakogianni, Margarita

2009-01-01

Contradictory experimental findings and theoretical interpretations have spurred intense debate over the electrical properties of the DNA double helix. In the present review article the various factors responsible for these divergences are discussed. The enlightenment of this issue could improve long range chemistry of oxidative DNA damage and repair processes, monitoring protein-DNA interactions and possible applications in nano-electronic circuit technology. The update experimental situation concerning measurements of the electrical conductivity is given. The character of the carriers responsible for the electrical conductivity measured in DNA is investigated. A theoretical model for the temperature dependence of the electrical conductivity of DNA is presented, based on microscopic models and percolation theoretical arguments. The theoretical results, excluding or including correlation effects, are applied to recent experimental findings for DNA, considering it as a one dimensional molecular wire. The results indicate that correlation effects are probably responsible for large hopping distances in DNA samples. Other theoretical conductivity models proposed for the interpretation of the responsible transport mechanism are also reviewed. Some of the most known and pioneering works on DNA's nano-applications, future developments and perspectives along with current technological limitations and patents are presented and discussed.

SpaceWire Data Handling Demonstration System

NASA Astrophysics Data System (ADS)

Mills, S.; Parkes, S. M.; O'Gribin, N.

2007-08-01

The SpaceWire standard was published in 2003 with the aim of providing a standard for onboard communications, defining the physical and data link layers of an interconnection, in order to improve reusability, reliability and to reduce the cost of mission development. The many benefits which it provides mean that it has already been used in a number of missions, both in Europe and throughout the world. Recent work by the SpaceWire community has included the development of higher level protocols for SpaceWire, such as the Remote Memory Access Protocol (RMAP) which can be used for many purposes, including the configuration of SpaceWire devices. Although SpaceWire has become very popular, the various ways in which it can be used are still being discovered, as are the most efficient ways to use it. At the same time, some in the space industry are not even aware of SpaceWire's existence. This paper describes the SpaceWire Data Handling Demonstration System that has been developed by the University of Dundee. This system simulates an onboard data handling network based on SpaceWire. It uses RMAP for all communication, and so demonstrates how SpaceWire and standardised higher level protocols can be used onboard a spacecraft. The system is not only a good advert for those who are unfamiliar with the benefits of SpaceWire, it is also a useful tool for those using SpaceWire to test ideas.

Selected developments in laser wire stripping. [cutting insulation from aerospace-type wires and cables

NASA Technical Reports Server (NTRS)

1977-01-01

The operation of mechanical and thermal strippers and the early development of laser wire strippers are reviewed. NASA sponsored development of laser wire stripping for space shuttle includes bench-type strippers as well as an advanced portable hand-held stripper which incorporates a miniaturized carbon dioxide laser and a rotating optics unit with a gas-jet assist and debris exhaust. Drives and controls girdle the wire and slit the remaining slug without manual assistance. This unit can strip wire sizes 26 through 12 gage. A larger-capacity hand-held unit for wire sizes through 1/0 gage was built using a neodynium-doped yttrium aluminum garnet (Nd:YAG) laser. The hand-held units have a flexible umbilical cable to an accompanying cart that carries the power supply, gas supply, cooling unit, and the controls.

Investigation of factors affecting the heater wire method of calibrating fine wire thermocouples

NASA Technical Reports Server (NTRS)

Keshock, E. G.

1972-01-01

An analytical investigation was made of a transient method of calibrating fine wire thermocouples. The system consisted of a 10 mil diameter standard thermocouple (Pt, Pt-13% Rh) and an 0.8 mil diameter chromel-alumel thermocouple attached to a 20 mil diameter electrically heated platinum wire. The calibration procedure consisted of electrically heating the wire to approximately 2500 F within about a seven-second period in an environment approximating atmospheric conditions at 120,000 feet. Rapid periodic readout of the standard and fine wire thermocouple signals permitted a comparison of the two temperature indications. An analysis was performed which indicated that the temperature distortion at the heater wire produced by the thermocouple junctions appears to be of negligible magnitude. Consequently, the calibration technique appears to be basically sound, although several practical changes which appear desirable are presented and discussed. Additional investigation is warranted to evaluate radiation effects and transient response characteristics.

Associations of Pd, U and Ag in the SiC layer of neutron-irradiated TRISO fuel

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

Lillo, Thomas; Rooyen, Isabella Van

2015-05-01

Knowledge of the associations and composition of fission products in the neutron irradiated SiC layer of high-temperature gas reactor TRISO fuel is important to the understanding of various aspects of fuel performance that presently are not well understood. Recently, advanced characterization techniques have been used to examine fuel particles from the Idaho National Laboratory’s AGR-1 experiment. Nano-sized Ag and Pd precipitates were previously identified in grain boundaries and triple points in the SiC layer of irradiated TRISO nuclear fuel. Continuation of this initial research is reported in this paper and consists of the characterization of a relatively large number ofmore » nano-sized precipitates in three areas of the SiC layer of a single irradiated TRISO nuclear fuel particle using standardless EDS analysis on focused ion beam-prepared transmission electron microscopy samples. Composition and distribution analyses of these precipitates, which were located on grain boundaries, triple junctions and intragranular precipitates, revealed low levels, generally <10 atomic %, of palladium, silver and/or uranium with palladium being the most common element found. Palladium by itself, or associated with either silver or uranium, was found throughout the SiC layer. A small number of precipitates on grain boundaries and triple junctions were found to contain only silver or silver in association with palladium while uranium was always associated with palladium but never found by itself or in association with silver. Intergranular precipitates containing uranium were found to have migrated ~23 μm along a radial direction through the 35 μm thick SiC coating during the AGR-1 experiment while silver-containing intergranular precipitates were found at depths up to ~24 μm in the SiC layer. Also, Pd-rich, nano-precipitates (~10 nm in diameter), without evidence for the presence of either Ag or U, were revealed in intragranular regions throughout the SiC layer. Because

Towards plant wires.

PubMed

Adamatzky, Andrew

2014-08-01

In experimental laboratory studies we evaluate a possibility of making electrical wires from living plants. In scoping experiments we use lettuce seedlings as a prototype model of a plant wire. We approximate an electrical potential transfer function by applying direct current voltage to the lettuce seedlings and recording output voltage. We analyse oscillation frequencies of the output potential and assess noise immunity of the plant wires. Our findings will be used in future designs of self-growing wetware circuits and devices, and integration of plant-based electronic components into future and emergent bio-hybrid systems. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Twin-Axial Wire Antenna

DTIC Science & Technology

2015-08-06

12 and 14 can be of differing gauges and can be either stranded or solid. In a prototype, both conductors were made from #22 solid copper wire ...08-2015 Publication Twin-Axial Wire Antenna David A. Tonn Naval Under Warfare Center Division, Newport 1176 Howell St., Code 00L, Bldg 102T...Approved for Public Release Distribution is unlimited Attorney Docket No. 300030 1 of 10 TWIN-AXIAL WIRE ANTENNA STATEMENT OF GOVERNMENT INTEREST

Ignition and Combustion Characteristics of Nanoscale Al/AgIO3: A Potential Energetic Biocidal System

DTIC Science & Technology

2011-01-01

the actual particle morphology consists of thin platelets , roughly 1 mm in diam- eter. Silver iodide was purchased from Sigma Aldrich, and the size was...2008), and shows that mixing is limited by clumping of both ingredients. The AgIO3 has a platelet -like morphology, and could potentially mix...in this study is 80 nm from NanoTechnologies. The CuO in this study is 45 nm from Technanogy. Each sample was fuel rich in this study with equivalency

Ag implantation-induced modification of Ni-Ti shape memory alloy thin films

NASA Astrophysics Data System (ADS)

Kumar, V.; Singhal, R.; Vishnoi, R.; Banerjee, M. K.; Sharma, M. C.; Asokan, K.; Kumar, M.

2017-08-01

Nanocrystalline thin films of Ni-Ti shape memory alloy are deposited on an Si substrate by the DC-magnetron co-sputtering technique and 120 keV Ag ions are implanted at different fluences. The thickness and composition of the pristine films are determined by Rutherford Backscattering Spectrometry (RBS). X-Ray diffraction (XRD), atomic force microscopy (AFM) and four-point probe resistivity methods have been used to study the structural, morphological and electrical transport properties. XRD analysis has revealed the existence of martensitic and austenite phases in the pristine film and also evidenced the structural changes in Ag-implanted Ni-Ti films at different fluences. AFM studies have revealed that surface roughness and grain size of Ni-Ti films have decreased with an increase in ion fluence. The modifications in the mechanical behaviour of implanted Ni-Ti films w.r.t pristine film is determined by using a Nano-indentation tester at room temperature. Higher hardness and the ratio of higher hardness (H) to elastic modulus (Er) are observed for the film implanted at an optimized fluence of 9 × 1015 ions/cm2. This improvement in mechanical behaviour could be understood in terms of grain refinement and dislocation induced by the Ag ion implantation in the Ni-Ti thin films.

Study on Electro-polymerization Nano-micro Wiring System Imitating Axonal Growth of Artificial Neurons towards Machine Learning

NASA Astrophysics Data System (ADS)

Dang, Nguyen Tuan; Akai-Kasada, Megumi; Asai, Tetsuya; Saito, Akira; Kuwahara, Yuji; Hokkaido University Collaboration

2015-03-01

Machine learning using the artificial neuron network research is supposed to be the best way to understand how the human brain trains itself to process information. In this study, we have successfully developed the programs using supervised machine learning algorithm. However, these supervised learning processes for the neuron network required the very strong computing configuration. Derivation from the necessity of increasing in computing ability and in reduction of power consumption, accelerator circuits become critical. To develop such accelerator circuits using supervised machine learning algorithm, conducting polymer micro/nanowires growing process was realized and applied as a synaptic weigh controller. In this work, high conductivity Polypyrrole (PPy) and Poly (3, 4 - ethylenedioxythiophene) PEDOT wires were potentiostatically grown crosslinking the designated electrodes, which were prefabricated by lithography, when appropriate square wave AC voltage and appropriate frequency were applied. Micro/nanowire growing process emulated the neurotransmitter release process of synapses inside a biological neuron and wire's resistance variation during the growing process was preferred to as the variation of synaptic weigh in machine learning algorithm. In a cooperation with Graduate School of Information Science and Technology, Hokkaido University.

Understanding the densification process of Bi2Sr2CaCu2Ox round wires with overpressure processing and its effect on critical current density

PubMed Central

Matras, M. R.; Jiang, J.; Larbalestier, D. C.; Hellstrom, E. E.

2016-01-01

Overpressure (OP) processing increases the critical current density (JC) of Bi2Sr2CaCu2Ox (2212) round wires by shrinking the surrounding Ag matrix around the 2212 filaments, driving them close to full density and greatly increasing the 2212 grain connectivity. Indeed densification is vital for attaining the highest JC. Here, we investigate the time and temperature dependence of the wire densification. We find that the wire diameter decreases by 3.8 ± 0.3 % after full heat treatment at 50 atm and 100 atm OP. At 50 atm OP pressure, the filaments start densifying above 700 °C and reach a 3.30 ± 0.07 % smaller diameter after 2 h at 820 °C, which is below the melting point of 2212 powder. The densification is homogeneous and does not change the filament shape before melting. The growth of non-superconducting phases is observed at 820 °C, suggesting that time should be minimized at high temperature prior to melting the 2212 powder. Study of an open-ended 2.2 m long wire sample shows that full densification and the high OP JC (JC varies by about 3.1 times over the 2.2 m long wire) is reached about 1 m from the open ends, thus showing that coil-length wires can be protected from leaky seals by adding at least 1 m of sacrificial wire at each end. PMID:28479675

Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

NASA Astrophysics Data System (ADS)

Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

2011-07-01

Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

Wire Composition: Its Effect on Metal Disintegration and Particle Formation in Twin-Wire Arc-Spraying Process

NASA Astrophysics Data System (ADS)

Tillmann, W.; Abdulgader, M.

2013-03-01

The wire tips in twin-wire arc-spraying (TWAS) are heated in three different zones. A high-speed camera was used to observe the melting behavior, metal breakup, and particle formation under different operating conditions. In zone (I), the wire tips are melted (liquidus metal) and directly atomized in the form of smaller droplets. Their size is a function of the specific properties of the molten metal and the exerting aerodynamic forces. Zone (II) is directly beneath zone (I) and the origin of the extruded metal sheets at the wire tips. The extruded metal sheets in the case of cored wires are shorter than those observed while using solid wires. In this study, the effects of adjustable parameters and powder filling on melting behavior, particle formation, and process instability were revealed, and a comparison between solid and cored wires was made. The findings can improve the accuracy of the TWAS process modeling.

In situ solid-state fabrication of hybrid AgCl/AgI/AgIO3 with improved UV-to-visible photocatalytic performance.

PubMed

Xie, Jing; Cao, Yali; Jia, Dianzeng; Li, Yizhao; Wang, Kun; Xu, Hui

2017-09-28

The AgCl/AgI/AgIO 3 composites were synthesized through a one-pot room-temperature in situ solid-state approach with the feature of convenient and eco-friendly. The as-prepared composites exhibit superior photocatalytic performance than pure AgIO 3 for the degradation of methyl orange (MO) under both UV and visible light irradiation. The photodegradation rate toward MO of the AgCl/AgI/AgIO 3 photocatalyst can reach 100% after 12 min irradiation under UV light, or 85.4% after 50 min irradiation under visible light, being significantly higher than AgCl, AgI, AgIO 3 and AgI/AgIO 3 . In addition, the AgCl/AgI/AgIO 3 photocatalyst possesses strong photooxidation ability for the degradation of rhodamine B (RhB), methylene blue (MB), phenol, bisphenol A (BPA) and tetracycline hydrochloride under visible light irradiation. The reactive species capture experiments confirmed that the h + and •O 2- play an essential role during the photocatalytic process under UV light or visible light irradiation. The enhanced effect may be beneficial from the enhanced light adsorption in full spectrum and increased separation efficiency of photogenerated hole-electron pairs, which can be ascribed to the synergistic effect among AgCl, AgI and AgIO 3 nanoplates in AgCl/AgI/AgIO 3 composites.

Effects of electrolytes and surfactants on the morphology and stability of advanced silver nano-materials

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

Obaid, Abdullah Yousif; AL-Thabaiti, Shaeel Ahmed; El-Mossalamy, E.H.

2013-03-15

Highlights: ► Stoichiometric ratio of S{sub 2}O{sub 3}{sup 2−} and Ag{sup +} ions are responsible to the formation of prefect transparent yellow colored silver sol. ► Higher S{sub 2}O{sub 3}{sup 2−} concentrations has damping effect. ► Head group of the surfactants and nature of the electrolytes have significant effect on the stability of silver nanoparticles. - Abstract: The impact of electrolytes, stabilizing and/or capping agents on morphology of colloidal silver nano-materials (AgNPs) has been studied spectroscopically. Sodium thiosulfate acts as reducing-, stabilizing- and damping-agents. Stoichiometric ratios of S{sub 2}O{sub 3}{sup 2−} and Ag{sup +} ions were responsible to the formationmore » stable and prefect transparent dark yellow colored AgNPs. The S{sub 2}O{sub 3}{sup 2−}-stabilized AgNPs were significantly more stable in inorganic electrolytes (NaNO{sub 3}, Na{sub 2}SO{sub 4}, Na{sub 2}CO{sub 3} and KBr). S{sub 2}O{sub 3}{sup 2−} is adsorbed more strongly than the used other anions. The addition of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) has significant effects on the absorbance of S{sub 2}O{sub 3}{sup 2−}-stabilized AgNPs which can be rationalized in terms of electrostatic attraction and repulsion between the adsorbed S{sub 2}O{sub 3}{sup 2−} ions on to the surface of AgNPs and cationic and/or anionic head groups of used surfactants, respectively. Transmission electron microscopy images suggest that AgNPs are polydispersed, spherical and exhibiting an interesting irregular morphology.« less

Effects of photon field on heat transport through a quantum wire attached to leads

NASA Astrophysics Data System (ADS)

Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

2018-01-01

We theoretically investigate photo-thermoelectric transport through a quantum wire in a photon cavity coupled to electron reservoirs with different temperatures. Our approach, based on a quantum master equation, allows us to investigate the influence of a quantized photon field on the heat current and thermoelectric transport in the system. We find that the heat current through the quantum wire is influenced by the photon field resulting in a negative heat current in certain cases. The characteristics of the transport are studied by tuning the ratio, ħωγ /kB ΔT, between the photon energy, ħωγ, and the thermal energy, kB ΔT. The thermoelectric transport is enhanced by the cavity photons when kB ΔT > ħωγ. By contrast, if kB ΔT < ħωγ, the photon field is dominant and a suppression in the thermoelectric transport can be found in the case when the cavity-photon field is close to a resonance with the two lowest one-electron states in the system. Our approach points to a new technique to amplify thermoelectric current in nano-devices.

29 CFR 1919.79 - Wire rope.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 7 2011-07-01 2011-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same construction...

29 CFR 1919.79 - Wire rope.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 7 2010-07-01 2010-07-01 false Wire rope. 1919.79 Section 1919.79 Labor Regulations...) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.79 Wire rope. (a) Wire rope and replacement wire rope shall be of the same size, same or better grade, and same construction...

NASA wiring for space applications program

NASA Technical Reports Server (NTRS)

Schulze, Norman

1995-01-01

An overview of the NASA Wiring for Space Applications Program and its relationship to NASA's space technology enterprise is given in viewgraph format. The mission of the space technology enterprise is to pioneer, with industry, the development and use of space technology to secure national economic competitiveness, promote industrial growth, and to support space missions. The objectives of the NASA Wiring for Space Applications Program is to improve the safety, performance, and reliability of wiring systems for space applications and to develop improved wiring technologies for NASA flight programs and commercial applications. Wiring system failures in space and commercial applications have shown the need for arc track resistant wiring constructions. A matrix of tests performed versus wiring constructions is presented. Preliminary data indicate the performance of the Tensolite and Filotex hybrid constructions are the best of the various candidates.

Welding wire pressure sensor assembly

NASA Technical Reports Server (NTRS)

Morris, Timothy B. (Inventor); Milly, Peter F., Sr. (Inventor); White, J. Kevin (Inventor)

1994-01-01

The present invention relates to a device which is used to monitor the position of a filler wire relative to a base material being welded as the filler wire is added to a welding pool. The device is applicable to automated welding systems wherein nonconsumable electrode arc welding processes are utilized in conjunction with a filler wire which is added to a weld pool created by the electrode arc. The invention senses pressure deviations from a predetermined pressure between the filler wire and the base material, and provides electrical signals responsive to the deviations for actuating control mechanisms in an automatic welding apparatus so as to minimize the pressure deviation and to prevent disengagement of the contact between the filler wire and the base material.

Low-Temperature Preparation of Ag-Doped ZnO Nanowire Arrays, DFT Study, and Application to Light-Emitting Diode.

PubMed

Pauporté, Thierry; Lupan, Oleg; Zhang, Jie; Tugsuz, Tugba; Ciofini, Ilaria; Labat, Frédéric; Viana, Bruno

2015-06-10

Doping ZnO nanowires (NWs) by group IB elements is an important challenge for integrating nanostructures into functional devices with better and tuned performances. The growth of Ag-doped ZnO NWs by electrodeposition at 90 °C using a chloride bath and molecular oxygen precursor is reported. Ag acts as an electrocatalyst for the deposition and influences the nucleation and growth of the structures. The silver atomic concentration in the wires is controlled by the additive concentration in the deposition bath and a content up to 3.7 atomic % is reported. XRD analysis shows that the integration of silver enlarges the lattice parameters of ZnO. The optical measurements also show that the direct optical bandgap of ZnO is reduced by silver doping. The bandgap shift and lattice expansion are explained by first principle calculations using the density functional theory (DFT) on the silver impurity integration as an interstitial (Ag(i)) and as a substitute of zinc atom (Ag(Zn)) in the crystal lattice. They notably indicate that Ag(Zn) doping forms an impurity band because of Ag 4d and O 2p orbital interactions, shifting the Fermi level toward the valence band. At least, Ag-doped ZnO vertically aligned nanowire arrays have been epitaxially grown on GaN(001) substrate. The heterostructure has been inserted in a light emitting device. UV-blue light emission has been achieved with a low emission threshold of 5 V and a tunable red-shifted emission spectrum related to the bandgap reduction induced by silver doping of the ZnO emitter material.

Smooth ZnO:Al-AgNWs Composite Electrode for Flexible Organic Light-Emitting Device.

PubMed

Wang, Hu; Li, Kun; Tao, Ye; Li, Jun; Li, Ye; Gao, Lan-Lan; Jin, Guang-Yong; Duan, Yu

2017-12-01

The high interest in organic light-emitting device (OLED) technology is largely due to their flexibility. Up to now, indium tin oxide (ITO) films have been widely used as transparent conductive electrodes (TCE) in organic opto-electronic devices. However, ITO films, typically deposited on glass are brittle and they make it difficult to produce flexible devices, restricting their use for flexible devices. In this study, we report on a nano-composite TCE, which is made of a silver nanowire (AgNW) network, combined with aluminum-doped zinc oxide (ZnO:Al, AZO) by atomic layer deposition. The AgNWs/AZO composite electrode on photopolymer substrate shows a low sheet resistance of only 8.6 Ω/sq and a high optical transmittance of about 83% at 550 nm. These values are even comparable to conventional ITO on glass. In addition, the electrodes also have a very smooth surface (0.31 nm root-mean-square roughness), which is flat enough to contact the OLED stack. Flexible OLED were built with AgNWs/AZO electrodes, which suggests that this approach can replace conventional ITO TCEs in organic electronic devices in the future.

Smooth ZnO:Al-AgNWs Composite Electrode for Flexible Organic Light-Emitting Device

NASA Astrophysics Data System (ADS)

Wang, Hu; Li, Kun; Tao, Ye; Li, Jun; Li, Ye; Gao, Lan-Lan; Jin, Guang-Yong; Duan, Yu

2017-01-01

The high interest in organic light-emitting device (OLED) technology is largely due to their flexibility. Up to now, indium tin oxide (ITO) films have been widely used as transparent conductive electrodes (TCE) in organic opto-electronic devices. However, ITO films, typically deposited on glass are brittle and they make it difficult to produce flexible devices, restricting their use for flexible devices. In this study, we report on a nano-composite TCE, which is made of a silver nanowire (AgNW) network, combined with aluminum-doped zinc oxide (ZnO:Al, AZO) by atomic layer deposition. The AgNWs/AZO composite electrode on photopolymer substrate shows a low sheet resistance of only 8.6 Ω/sq and a high optical transmittance of about 83% at 550 nm. These values are even comparable to conventional ITO on glass. In addition, the electrodes also have a very smooth surface (0.31 nm root-mean-square roughness), which is flat enough to contact the OLED stack. Flexible OLED were built with AgNWs/AZO electrodes, which suggests that this approach can replace conventional ITO TCEs in organic electronic devices in the future.

30 CFR 77.1430 - Wire ropes; scope.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Wire ropes; scope. 77.1430 Section 77.1430... Hoisting Wire Ropes § 77.1430 Wire ropes; scope. (a) Sections 77.1431 through 77.1438 apply to wire ropes.... (b) These standards do not apply to wire ropes used for elevators. ...

30 CFR 77.1430 - Wire ropes; scope.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Wire ropes; scope. 77.1430 Section 77.1430... Hoisting Wire Ropes § 77.1430 Wire ropes; scope. (a) Sections 77.1431 through 77.1438 apply to wire ropes.... (b) These standards do not apply to wire ropes used for elevators. ...

Modified pulse laser deposition of Ag nanostructure as intermediate for low temperature Cu-Cu bonding

NASA Astrophysics Data System (ADS)

Liu, Ziyu; Cai, Jian; Wang, Qian; Liu, Lei; Zou, Guisheng

2018-07-01

To lower the Cu-Cu bonding temperature and save the time of the bonding process applied for 3D integration, the Ag nanostructure deposited by pulsed laser deposition (PLD) was designed and decorated on the Cu pads as intermediate. Influences of different PLD process parameters on the designed Ag nanostructure morphology were investigated in this work. The large nanoparticles (NP) defects, NPs coverage rate on the Cu pad, and NPs size distribution were adopted to evaluate the PLD parameters based on the NPs morphology observation and the Cu-Cu bonding quality. The medium laser power of 0.8 W, smaller distance between target and substrate, and protective container should be applied in the optimized PLD to obtain the Ag nanostructure. Then a loose 3D mesh Ag nanostructure consisted of the protrusions and grooves was formed and the morphology observation proved the nanostructure deposition mechanism was contributed to the block of nano-film nucleation and nanoparticles absorption. Finally, the relationship between the bonding temperature and pressure suitable for the Ag nanostructure had been determined based on shear strength and interface observation. The results revealed the combination of higher bonding temperature (250 °C) and lower pressure (20 MPa), or lower bonding temperature (180 °C) and higher pressure (50 MPa) can both achieve the bonding process with the short bonding time of 5 min and annealing at 200 °C for 25 min in vacuum furnace.

Negligible shift of 3Ag- potential in longer-chain carotenoids as revealed by a single persistent peak of 3Ag-→1Ag- stimulated emission followed by 3Ag-←1Ag- transient-absorption

NASA Astrophysics Data System (ADS)

Li, Chunyong; Miki, Takeshi; Kakitani, Yoshinori; Koyama, Yasushi; Nagae, Hiroyoshi

2007-12-01

Upon excitation of lycopene, anhydrorhodovibrin or spirilloxanthin to the 1Bu+(0) state, stimulated emission followed by transient-absorption was observed as a single peak with the 3Ag-(0) energy that had been determined by measurement of resonance-Raman excitation profiles. This observation was explained in terms of negligible shift of the 3Ag- potential, in reference to the 1Ag- potential, where only the 3Ag-(υ)→1Ag-(υ) emission and the 3Ag-(υ)←1Ag-(υ) absorption become allowed during the vibrational relaxation of υ = 2 → 1 → 0, starting from the 3Ag-(2) level generated by diabatic internal conversion from the 1Bu+(0) level, in anhydrorhodovibrin, for example.

Multifilament Cable Wire versus Conventional Wire for Sternal Closure in Patients Undergoing Major Cardiac Surgery.

PubMed

Oh, You Na; Ha, Keong Jun; Kim, Joon Bum; Jung, Sung-Ho; Choo, Suk Jung; Chung, Cheol Hyun; Lee, Jae Won

2015-08-01

Stainless steel wiring remains the most popular technique for primary sternal closure. Recently, a multifilament cable wiring system (Pioneer Surgical Technology Inc., Marquette, MI, USA) was introduced for sternal closure and has gained wide acceptance due to its superior resistance to tension. We aimed to compare conventional steel wiring to multifilament cable fixation for sternal closure in patients undergoing major cardiac surgery. Data were collected retrospectively on 1,354 patients who underwent sternal closure after major cardiac surgery, using either the multifilament cable wiring system or conventional steel wires between January 2009 and October 2010. The surgical outcomes of these two groups of patients were compared using propensity score matching based on 18 baseline patient characteristics. Propensity score matching yielded 392 pairs of patients in the two groups whose baseline profiles showed no significant differences. No significant differences between the two groups were observed in the rates of early mortality (2.0% vs. 1.3%, p=0.578), major wound complications requiring reconstruction (1.3% vs. 1.3%, p>0.99), minor wound complications (3.6% vs. 2.0%, p=0.279), or mediastinitis (0.8% vs. 1.0%, p=1.00). Patients in the multifilament cable group had fewer sternal bleeding events than those in the conventional wire group, but this tendency was not statistically significant (4.3% vs. 7.4%, p=0.068). The surgical outcomes of sternal closure using multifilament cable wires were comparable to those observed when conventional steel wires were used. Therefore, the multifilament cable wiring system may be considered a viable option for sternal closure in patients undergoing major cardiac surgery.

AgCl/Ag3PO4: A stable Ag-Based nanocomposite photocatalyst with enhanced photocatalytic activity for the degradation of parabens.

PubMed

Guo, Jianhao; Shi, Huixian; Huang, Xiaobo; Shi, Huifang; An, Zhongfu

2018-04-01

An AgCl/Ag 3 PO 4 composite has been successfully fabricated by a simple desorption-precipitation method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV/Vis), and photoluminescence (PL) have been used to study the structural and physicochemical characteristics of the AgCl/Ag 3 PO 4 composite. The photocatalytic activity of the AgCl/Ag 3 PO 4 composite has been tested by the degradation of parabens under visible-light irradiation. 100% of MPB was degraded within 40 min in the AgCl/Ag 3 PO 4 -visible light system. Moreover, the photocatalytic activity of AgCl/Ag 3 PO 4 remained at 94% of the original level after five runs, which was much higher than that of pure Ag 3 PO 4 (25%). The obtained results confirmed that the AgCl/Ag 3 PO 4 composite exhibited significantly higher photocatalytic performance and improved stability compared with bare Ag 3 PO 4 . The enhanced photocatalytic performance of the AgCl/Ag 3 PO 4 composite could be mainly attributed to highly efficient charge separation through a synergistic effect of AgCl, Ag 3 PO 4 , and in situ photo-reduced Ag nanoparticles. Trapping experiments confirmed h + and ·O 2 - to be the two main active species in the photocatalytic process. Finally, a possible photocatalytic mechanism for the charge-transfer process is proposed to account for the enhanced photocatalytic performance of the AgCl/Ag 3 PO 4 composite. Copyright © 2018 Elsevier Inc. All rights reserved.

Whole article corrigendum: "Surface-plasmon-enhanced GaN-LED based on the multilayered rectangular nano-grating" [Optics Communications 322 (2014) 66-72

NASA Astrophysics Data System (ADS)

Zhu, Jun; Zhang, Haosu; Zhu, Zhendong; Li, Qunqing; Jin, Guofan

2017-02-01

This article proposes a surface-plasmon-enhanced GaN-LED based on the multilayered rectangular nano-grating. This structure contains a SiO2 film, an Ag film and a HfO2 film sequentially coated on the rectangularly-patterned p-GaN layer. The Ag film is used to enhance the internal quantum efficiency. The HfO2 cover-layer symmetrizes the distribution of refractive index besides the Ag film to improve the light extraction efficiency and surface-plasmon (SP) extraction efficiency. The inserted SiO2 layer is utilized to further improve the SP extraction efficiency. The properties of SP modes and Purcell effect in this structure are investigated. The photoluminescence experiments demonstrate that its peak intensity of top-emission is about 2.5 times greater than that from the reference structure covered by a single-layer Ag film on the rectangularly-patterned p-GaN layer.

29 CFR 1926.1413 - Wire rope-inspection.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Apparent deficiencies in this category are: (A) Visible broken wires, as follows: (1) In running wire ropes: Six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope... around the rope. (2) In rotation resistant ropes: Two randomly distributed broken wires in six rope...

29 CFR 1926.1413 - Wire rope-inspection.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Apparent deficiencies in this category are: (A) Visible broken wires, as follows: (1) In running wire ropes: Six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope... around the rope. (2) In rotation resistant ropes: Two randomly distributed broken wires in six rope...

29 CFR 1926.1413 - Wire rope-inspection.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Apparent deficiencies in this category are: (A) Visible broken wires, as follows: (1) In running wire ropes: Six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope... around the rope. (2) In rotation resistant ropes: Two randomly distributed broken wires in six rope...

The study of hard x-ray emission and electron beam generation in wire array Z-pinch and X-pinch plasmas at university-scale generators

NASA Astrophysics Data System (ADS)

Shrestha, Ishor Kumar

The studies of hard x-ray (HXR) emission and electron beam generation in Z-pinch plasmas are very important for Inertial Confinement Fusion (ICF) research and HXR emission application for sources of K-shell and L-shell radiation. Energetic electron beams from Z-pinch plasmas are potentially a problem in the development of ICF. The electron beams and the accompanying HXR emission can preheat the fuel of a thermonuclear target, thereby preventing the fuel compression from reaching densities required for the ignition of a fusion reaction. The photons above 3-4 keV radiated from a Z pinch can provide detailed information about the high energy density plasmas produced at stagnation. Hence, the investigation of characteristics of hard x-rays and electron beams produced during implosions of wire array loads on university scale-generators may provide important data for future ICF, sources of K-shell and L-shell radiations and basic plasma research. This dissertation presents the results of experimental studies of HXR and electron beam generation in wire-array and X-pinch on the 1.7 MA, 100-ns current rise time Zebra generator at University of Nevada, Reno and 1-MA 100-ns current rise-time Cornell Beam Research Accelerator (COBRA) at Cornell University. The experimental study of characteristics of HXR produced by multi-planar wire arrays, compact cylindrical wire array (CCWA) and nested cylindrical wire array (NCWA) made from Al, Cu, Mo, Ag, W and Au were analyzed. The dependence of the HXR yield and power on geometry of the load, the wire material, and load mass was observed. The presence of aluminum wires in the load with the main material such as stainless steel, Cu, Mo, Ag, W or Au in combined wire array decreases HXR yield. The comparison of emission characteristics of HXR and generation of electron beams in CCWA and NCWA on both the high impedance Zebra generator and low impedance COBRA generator were investigated. Some of the "cold" K- shell spectral lines (0.7-2.3�

Plasma arc torch with coaxial wire feed

DOEpatents

Hooper, Frederick M

2002-01-01

A plasma arc welding apparatus having a coaxial wire feed. The apparatus includes a plasma arc welding torch, a wire guide disposed coaxially inside of the plasma arc welding torch, and a hollow non-consumable electrode. The coaxial wire guide feeds non-electrified filler wire through the tip of the hollow non-consumable electrode during plasma arc welding. Non-electrified filler wires as small as 0.010 inches can be used. This invention allows precision control of the positioning and feeding of the filler wire during plasma arc welding. Since the non-electrified filler wire is fed coaxially through the center of the plasma arc torch's electrode and nozzle, the wire is automatically aimed at the optimum point in the weld zone. Therefore, there is no need for additional equipment to position and feed the filler wire from the side before or during welding.

Enhanced optical and electrochemical properties of polyaniline/cobalt oxide nano composite

NASA Astrophysics Data System (ADS)

Niranjana, M.; Yesappa, L.; Ashokkumar, S. P.; Vijeth, H.; Basappa, M.; Devendrappa, H.

2018-05-01

Polyaniline and its composites at different wt. % of Cobalt oxide nano (PDC1, PDC2 and PDC5) were prepared by in-situ chemical reaction method The optical property was carried out using UV-Vis. Absorption Spectroscopy. The electrochemical property like cyclic voltammetry and galvonostatic charging-discharging was carried out for PANI and PDC nanocomposite electrode materials. A specific capacitance of 212.08 F/g and 336.41 F/g with scan rates 100 and 200 mV/s at 0.4 A/g current density respectively. These results are suggesting PDC composite is a prominent candidate for supercapacitor properties applications.

Understanding the densification process of Bi2Sr2CaCu2O x round wires with overpressure processing and its effect on critical current density

NASA Astrophysics Data System (ADS)

Matras, M. R.; Jiang, J.; Larbalestier, D. C.; Hellstrom, E. E.

2016-10-01

Overpressure (OP) processing increases the critical current density ({{\\boldsymbol{J}}}{{C}}) of Bi2Sr2CaCu2O x (2212) round wires by shrinking the surrounding Ag matrix around the 2212 filaments, driving them close to full density and greatly increasing the 2212 grain connectivity. Indeed densification is vital for attaining the highest {{\\boldsymbol{J}}}{{C}}. Here, we investigate the time and temperature dependence of the wire densification. We find that the wire diameter decreases by 3.8 ± 0.3% after full heat treatment at 50 atm and 100 atm OP. At 50 atm OP pressure, the filaments start densifying above 700 °C and reach a 3.30 ± 0.07% smaller diameter after 2 h at 820 °C, which is below the melting point of 2212 powder. The densification is homogeneous and does not change the filament shape before melting. The growth of non-superconducting phases is observed at 820 °C, suggesting that time should be minimized at high temperature prior to melting the 2212 powder. Study of an open-ended 2.2 m long wire sample shows that full densification and the high OP {{\\boldsymbol{J}}}{{C}} ({{\\boldsymbol{J}}}{{C}} varies by about 3.1 times over the 2.2 m long wire) is reached about 1 m from the open ends, thus showing that coil-length wires can be protected from leaky seals by adding at least 1 m of sacrificial wire at each end.

K-wire and tension band wire fixation in treating sternoclavicular joint dislocation.

PubMed

Chen, Qing-yu; Cheng, Shao-wen; Wang, Wei; Lin, Zhong-qin; Zhang, Wei; Kou, Dong-quan; Shen, Yue; Ying, Xiao-zhou; Cheng, Xiao-jie; Lv, Chuan-zhu; Peng, Lei

2011-02-01

To evaluate the feasibility and therapeutic effect of treating sternoclavicular joint dislocation by K-wire and tension band wire fixation, and to improve the safety and stability of this technique. This study consisted of 9 cases, 6 males and 3 females with the mean age of 25 years (range, 9-62 years). The causes were traffic accident in 7 cases, falling in 1 case and fight in 1 case. The duration from injury to operation was 2 hours to 7 days. There were 5 left dislocations and 4 right dislocations; 8 anterior dislocations and 1 posterior dislocation, including one combined with left scapular fracture and one with left olecranon fracture. Open reduction and internal fixation using K-wires and tension band wires were performed to treat dislocations. All patients were followed up for 6 to 24 months, 10 months on average. According to Rockwood's rating scale on postoperative sternoclavicular joint, 8 cases achieved excellent outcomes with an average score of 13.88, and the rest case achieved a good outcome with the score of 12. Anatomical reduction was obtained in all cases. There were no such postoperative complications as severe infection, injury to blood vessel and nerve, failure of fixation, etc. Patients were all satisfied with the anatomical reduction and functional recovery. The technique of K-wire and tension band wire fixation is safe, simple, effective, less invasive and has been successfully used in orthopedic surgery. It is effective in treating sternoclavicular joint dislocation though it has some disadvantages.

Localized surface plasmon resonances dominated giant lateral photovoltaic effect observed in ZnO/Ag/Si nanostructure

PubMed Central

Zhang, Ke; Wang, Hui; Gan, Zhikai; Zhou, Peiqi; Mei, Chunlian; Huang, Xu; Xia, Yuxing

2016-01-01

We report substantially enlarged lateral photovoltaic effect (LPE) in the ZnO/Ag/Si nanostructures. The maximum LPE sensitivity (55.05 mv/mm) obtained in this structure is about seven times larger than that observed in the control sample (7.88 mv/mm) of ZnO/Si. We attribute this phenomenon to the strong localized surface plasmon resonances (LSPRs) induced by nano Ag semicontinuous films. Quite different from the traditional LPE in PN junction type structures, in which light-generated carriers contributed to LPE merely depends on direct excitation of light in semiconductor, this work firstly demonstrates that, by introducing a super thin metal Ag in the interface between two different kinds of semiconductors, the nanoscale Ag embedded in the interface will produce strong resonance of localized field, causing extra intraband excitation, interband excitation and an enhanced direct excitation. As a consequence, these LSPRs dominated contributions harvest much more carriers, giving rise to a greatly enhanced LPE. In particular, this LSPRs-driven mechanism constitutes a sharp contrast to the traditional LPE operation mechanism. This work suggests a brand new LSPRs approach for tailoring LPE-based devices and also opens avenues of research within current photoelectric sensors area. PMID:26965713

Environmental risk assessment of engineered nano-SiO2 , nano iron oxides, nano-CeO2 , nano-Al2 O3 , and quantum dots.

PubMed

Wang, Yan; Nowack, Bernd

2018-05-01

Many research studies have endeavored to investigate the ecotoxicological hazards of engineered nanomaterials (ENMs). However, little is known regarding the actual environmental risks of ENMs, combining both hazard and exposure data. The aim of the present study was to quantify the environmental risks for nano-Al 2 O 3 , nano-SiO 2 , nano iron oxides, nano-CeO 2 , and quantum dots by comparing the predicted environmental concentrations (PECs) with the predicted-no-effect concentrations (PNECs). The PEC values of these 5 ENMs in freshwaters in 2020 for northern Europe and southeastern Europe were taken from a published dynamic probabilistic material flow analysis model. The PNEC values were calculated using probabilistic species sensitivity distribution (SSD). The order of the PNEC values was quantum dots < nano-CeO 2  < nano iron oxides < nano-Al 2 O 3  < nano-SiO 2 . The risks posed by these 5 ENMs were demonstrated to be in the reverse order: nano-Al 2 O 3  > nano-SiO 2  > nano iron oxides > nano-CeO 2  > quantum dots. However, all risk characterization values are 4 to 8 orders of magnitude lower than 1, and no risk was therefore predicted for any of the investigated ENMs at the estimated release level in 2020. Compared to static models, the dynamic material flow model allowed us to use PEC values based on a more complex parameterization, considering a dynamic input over time and time-dependent release of ENMs. The probabilistic SSD approach makes it possible to include all available data to estimate hazards of ENMs by considering the whole range of variability between studies and material types. The risk-assessment approach is therefore able to handle the uncertainty and variability associated with the collected data. The results of the present study provide a scientific foundation for risk-based regulatory decisions of the investigated ENMs. Environ Toxicol Chem 2018;37:1387-1395. © 2018 SETAC. © 2018 SETAC.

Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics Talk: Understanding Nano-scale Electronic Systems via Large-scale Computation

NASA Astrophysics Data System (ADS)

Cao, Chao

2009-03-01

Nano-scale physical phenomena and processes, especially those in electronics, have drawn great attention in the past decade. Experiments have shown that electronic and transport properties of functionalized carbon nanotubes are sensitive to adsorption of gas molecules such as H2, NO2, and NH3. Similar measurements have also been performed to study adsorption of proteins on other semiconductor nano-wires. These experiments suggest that nano-scale systems can be useful for making future chemical and biological sensors. Aiming to understand the physical mechanisms underlying and governing property changes at nano-scale, we start off by investigating, via first-principles method, the electronic structure of Pd-CNT before and after hydrogen adsorption, and continue with coherent electronic transport using non-equilibrium Green’s function techniques combined with density functional theory. Once our results are fully analyzed they can be used to interpret and understand experimental data, with a few difficult issues to be addressed. Finally, we discuss a newly developed multi-scale computing architecture, OPAL, that coordinates simultaneous execution of multiple codes. Inspired by the capabilities of this computing framework, we present a scenario of future modeling and simulation of multi-scale, multi-physical processes.

Electromagnetic scattering by a straight thin wire

NASA Technical Reports Server (NTRS)

Shamansky, Harry T.; Dominek, Allen K.; Peters, Leon, Jr.

1989-01-01

The traveling-wave energy, which multiply diffracts on a straight thin wire, is represented as a sum of terms, each with a distinct physical meaning, that can be individually examined in the time domain. Expressions for each scattering mechanism on a straight thin wire are cast in the form of four basic electromagnetic wave concepts: diffraction, attachment, launch, and reflection. Using the basic mechanisms from P. Ya. Ufimtsev (1962), each of the scattering mechanisms is included into the total scattered field for the straight thin wire. Scattering as a function of angle and frequency is then compared to the moment-method solution. These analytic expressions are then extended to a lossy wire with a simple approximate modification using the propagation velocity on the wire as derived from the Sommerfeld wave on a straight lossy wire. Both the perfectly conducting and lossy wire solutions are compared to moment-method results, and excellent agreement is found. As is common with asymptotic solutions, when the electrical length of wire is smaller than 0.2 lambda the results lose accuracy. The expressions modified to approximate the scattering for the lossy thin wire yield excellent agreement even for lossy wires where the wire radius is on the order of skin depth.

75 FR 60480 - In the Matter of Certain Bulk Welding Wire Containers and Components Thereof and Welding Wire...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-30

... Welding Wire Containers and Components Thereof and Welding Wire; Notice of Commission Determination To... within the United States after importation of certain bulk welding wire containers, components thereof, and welding wire by reason of infringement of certain claims of United States Patent Nos. 6,260,781; 6...

49 CFR 236.76 - Tagging of wires and interference of wires or tags with signal apparatus.

Code of Federal Regulations, 2010 CFR

2010-10-01

... with signal apparatus. 236.76 Section 236.76 Transportation Other Regulations Relating to... wires and interference of wires or tags with signal apparatus. Each wire shall be tagged or otherwise so... apparatus. [49 FR 3384, Jan. 26, 1984] Inspections and Tests; All Systems ...

49 CFR 236.76 - Tagging of wires and interference of wires or tags with signal apparatus.

Code of Federal Regulations, 2011 CFR

2011-10-01

... with signal apparatus. 236.76 Section 236.76 Transportation Other Regulations Relating to... wires and interference of wires or tags with signal apparatus. Each wire shall be tagged or otherwise so... apparatus. [49 FR 3384, Jan. 26, 1984] Inspections and Tests; All Systems ...

Wire metamaterials: physics and applications.

PubMed

Simovski, Constantin R; Belov, Pavel A; Atrashchenko, Alexander V; Kivshar, Yuri S

2012-08-16

The physics and applications of a broad class of artificial electromagnetic materials composed of lattices of aligned metal rods embedded in a dielectric matrix are reviewed. Such structures are here termed wire metamaterials. They appear in various settings and can operate from microwaves to THz and optical frequencies. An important group of these metamaterials is a wire medium possessing extreme optical anisotropy. The study of wire metamaterials has a long history, however, most of their important and useful properties have been revealed and understood only recently, especially in the THz and optical frequency ranges where the wire media correspond to the lattices of microwires and nanowires, respectively. Another group of wire metamaterials are arrays and lattices of nanorods of noble metals whose unusual properties are driven by plasmonic resonances. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determining the effects of green chemistry synthesized Ag-nisin nanoparticle on macrophage cells.