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1

Tribological and mechanical properties of Ti/TiAlN/TiAlCN nanoscale multilayer PVD coatings deposited on AISI H11 hot work tool steel  

NASA Astrophysics Data System (ADS)

A new [Ti/TiAlN/TiAlCN]5 multilayer coatings were deposited onto polished substrate AISI H11 (DIN 1.2343) steel by an industrial magnetron sputtering device. The tribological performance of the coated system was investigated by a ball-on-disk tribometer against 100Cr6 steel and Al2O3 balls. The friction coefficients and specific wear rates were measured at various normal loads (2, 5, 8, and 10 N) and sliding velocities (0.2, 0.4, and 0.8 m/s) in ambient air and dry conditions. The phase structure, composition, wear tracks morphologies, hardness, and film/substrate adhesion of the coatings were characterized by light-microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), 3D-surface analyzer, nanoindentation, and scratch tests. Results showed that the deposited coatings showed low wear rates in the scale of 10-15 m3/N m, low friction coefficients against 100Cr6 and Al2O3 balls in the range of 0.25-0.37, and good hardness in the range of 17-20 GPa. Results also revealed that the friction coefficients and disc wear rates decrease and increase, respectively with the increase in normal load and sliding velocity for both coating/Al2O3 and coating/100Cr6 sliding system. Compared with the uncoated-H11 substrate, the deposited coating exhibited superior tribological and mechanical properties. The dominant wear mechanism was abrasive wear for coating/Al2O3 pair, while for coating/100Cr6 pair, a combination of mild adhesive wear, severe adhesive wear, and abrasive wear (extensive plowing) were the dominant wear mechanisms at different applied normal loads.

AL-Bukhaiti, M. A.; Al-hatab, K. A.; Tillmann, W.; Hoffmann, F.; Sprute, T.

2014-11-01

2

Multifunctional nano-multilayered AlTiN\\/Cu PVD coating for machining of Inconel 718 superalloy  

Microsoft Academic Search

Machining of Ni-based aerospace alloys is one of the major challenges of modern manufacturing. Application of cemented carbide tooling with nano-multilayered AlTiN\\/Cu PVD coating results in a significant tool life improvement under conditions of turning the hard-to-machine aerospace Ni-based Inconel 718 superalloy. Studies of the structure, properties, tribological and wear performance of the nano-multilayered AlTiN\\/Cu PVD coating have been performed.

G. S. Fox-Rabinovich; K. Yamamoto; M. H. Aguirre; D. G. Cahill; S. C. Veldhuis; A. Biksa; G. Dosbaeva; L. S. Shuster

2010-01-01

3

Measurement of the perfection of nanoscale multilayers.  

PubMed

In modern materials science the characterisation of nanostructures is becoming increasingly important. For measurement of the quality of nanoscale multilayer arrangement with high spatial resolution a method is described that is based on the broadening of the spots in the Fourier transformation of transmission electron microscopic images of multilayer cross-sections. Using this method on Si/Ge superlattices with periodic lengths between 4 and 12 nm it could be quantitatively shown that the layer perfection decreases with increasing periodic length. The transition from elastic to plastic deformation between the Si and Ge layers at larger periodic lengths can be the reason for this behaviour. PMID:12802573

Thomas, J; Schumann, J; Kleint, C

2003-07-01

4

Deposition of nanoscale multilayer CrN\\/NbN physical vapor deposition coatings by high power impulse magnetron sputtering  

Microsoft Academic Search

Nanoscale multilayer CrN\\/NbN physical vapor deposition (PVD) coatings are gaining reputation for their high corrosion and wear resistance. However, the CrN\\/NbN films deposited by ABS (arc bond sputtering) technology have some limitations such as macrodroplets, porosity, and less dense structures. The novel HIPIMS (high power impulse magnetron sputtering) technique produces macroparticle-free, highly ionized metal plasma, which brings advantages in both

Y. P. Purandare; A. P. Ehiasarian; P. Eh. Hovsepian

2008-01-01

5

Nanoindentation of Nanoscale Ti/Au Multilayer Benjamin Revard and David Bahr  

E-print Network

Nanoindentation of Nanoscale Ti/Au Multilayer Composites Benjamin Revard and David Bahr School of Mechanical and Materials Engineering, Washington State University Introduction Nanoscale metallic multilayer potential applications as nanoscale engineering materials, including applications in the semiconductor

Collins, Gary S.

6

Mechanical and tribological properties of multilayered PVD TiN\\/CrN  

Microsoft Academic Search

By combining thin layers of PVD titanium nitride (TiN) with thin layers (preferably less than 10 nm) of another nitride, e.g., niobium nitride (NbN) or aluminum nitride (AlN), into a lamellae structure, a coating with superior properties to the homogenous coatings made from the constituents can be obtained. For example a very high hardness in combination with a high toughness,

Maria Nordin; Mats Larsson; Sture Hogmark

1999-01-01

7

Delamination and wear in drilling of carbon-fiber reinforced plastic composites using multilayer TiAlN\\/TiN PVD-coated tungsten carbide tools  

Microsoft Academic Search

This study aims to investigate drilling process in carbon-fiber reinforced plastic (CFRP) composites with multilayer TiAlN\\/TiN PVD-coated tungsten carbide drill. The effect of process parameters have been investigated in drilling of Hexcel M21-T700GC. Thrust force and torque were measured online throughout the drilling experiments. Delamination were observed using optical microscope and analyzed via a developed algorithm based on digital image

Ozden Isbilir; Elaheh Ghassemieh

2012-01-01

8

Deposition of nanoscale multilayer CrN/NbN physical vapor deposition coatings by high power impulse magnetron sputtering  

SciTech Connect

Nanoscale multilayer CrN/NbN physical vapor deposition (PVD) coatings are gaining reputation for their high corrosion and wear resistance. However, the CrN/NbN films deposited by ABS (arc bond sputtering) technology have some limitations such as macrodroplets, porosity, and less dense structures. The novel HIPIMS (high power impulse magnetron sputtering) technique produces macroparticle-free, highly ionized metal plasma, which brings advantages in both surface pretreatment and coating deposition stages of the PVD process. In this study, nanoscale multilayer CrN/NbN PVD coatings were pretreated and deposited with HIPIMS technology and compared with those deposited by HIPIMS-UBM (unbalanced magnetron) and by the ABS technique. In all cases Cr{sup +} etching was utilized to enhance adhesion by low energy ion implantation. The coatings were deposited at 400 deg. C with substrate biased (U{sub b}) at -75 V. During coating deposition, HIPIMS produced significantly high activation of nitrogen compared to the UBM as observed with mass spectroscopy. HIPIMS-deposited coatings revealed a bilayer period of 4.1 nm (total thickness: 2.9 {mu}m) and hardness of 3025 HK{sub 0.025}. TEM results revealed droplet free, denser microstructure with (200) preferred orientation for the HIPIMS coating owing to the increased ionization as compared to the more porous structure with random orientation observed in UBM coating. The dry sliding wear coefficient (K{sub c}) of the coating was 1.8x10{sup -15} m{sup 3} N{sup -1} m{sup -1}, whereas the steady state coefficient of friction was 0.32. Potentiodynamic polarization tests revealed higher E{sub corr} values, higher pitting resistance (around potentials +400 to +600 mV), and lower corrosion current densities for HIPIMS deposited coatings as compared to the coatings deposited by ABS or HIPIMS-UBM. The corrosion behavior of the coatings qualitatively improved with the progressive use of HIPIMS from pretreatment stage to the coating deposition step.

Purandare, Y. P.; Ehiasarian, A. P.; Hovsepian, P. Eh. [NanoTechnology Centre for PVD Research, Materials and Engineering Research Institute, Howard Street, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)

2008-03-15

9

Magnetic and transport properties of multilayer nanoscale antidot arrays C. C. Wang and A. O. Adeyeyea  

E-print Network

Magnetic and transport properties of multilayer nanoscale antidot arrays C. C. Wang and A. O to the interplay of different interlayer coupling mechanisms. The transport properties of the antidot arrays typically show a superposition of anisotropic and giant magnetoresistance effects, and the relative

Adeyeye, Adekunle

10

Residual stress characterization of Al/SiC nanoscale multilayers using X-ray  

SciTech Connect

Nanolayered composites are used in a variety of applications such as wear resistant coatings, thermal barrier coatings, optical and magnetic thin films, and biological coatings. Residual stresses produced in these materials during processing play an important role in controlling their microstructure and properties. In this paper, we have studied the residual stresses in model metal-ceramic Al/SiC nanoscale multilayers produced by physical vapor deposition (magnetron sputtering). X-ray synchrotron radiation was used to measure stresses in the multilayers using the sin{sup 2} {Psi} technique. The stresses were evaluated as a function of layer thicknesses of Al and SiC and also as a function of the number of layers. The stress state of Al in the multilayer was largely compressive, compared to single layer Al stresses. This is attributed to a peening mechanism due to bombardment of the Al layers by SiC and Ar neutrals during deposition. The stress evolution was numerically modeled by a simplified peening process to qualitatively explain the Al thickness-dependent residual stresses.

Singh, DRP [Arizona State University; Deng, X. [Arizona State University; Chawla, N. [Arizona State University; Bai, J. [Brookhaven National Laboratory (BNL); Hubbard, Camden R [ORNL; Tang, G [University of New Mexico, Albuquerque; Shen, Y-L [University of New Mexico, Albuquerque

2010-01-01

11

Quantitative x-ray phase imaging at the nanoscale by multilayer Laue lenses  

PubMed Central

For scanning x-ray microscopy, many attempts have been made to image the phase contrast based on a concept of the beam being deflected by a specimen, the so-called differential phase contrast imaging (DPC). Despite the successful demonstration in a number of representative cases at moderate spatial resolutions, these methods suffer from various limitations that preclude applications of DPC for ultra-high spatial resolution imaging, where the emerging wave field from the focusing optic tends to be significantly more complicated. In this work, we propose a highly robust and generic approach based on a Fourier-shift fitting process and demonstrate quantitative phase imaging of a solid oxide fuel cell (SOFC) anode by multilayer Laue lenses (MLLs). The high sensitivity of the phase to structural and compositional variations makes our technique extremely powerful in correlating the electrode performance with its buried nanoscale interfacial structures that may be invisible to the absorption and fluorescence contrasts. PMID:23419650

Yan, Hanfei; Chu, Yong S.; Maser, Jörg; Nazaretski, Evgeny; Kim, Jungdae; Kang, Hyon Chol; Lombardo, Jeffrey J.; Chiu, Wilson K. S.

2013-01-01

12

Theoretical explanation of Ag/Cu and Cu/Ni nanoscale multilayers softening Fengzhang Ren a,  

E-print Network

and the pressure exerted by Fermi electrons, which supports electron shells expansion at the expense of decreasing for electroplated Ag/Cu and Cu/Ni multilayers using a modified Thomas­Fermi­Dirac electron theory. Experiments on a modified Thomas­Fermi­Dirac electron theory. Developed relationship between the critical monolayer

Volinsky, Alex A.

13

Ion-beam induced transformations in nanoscale multilayers: Evolution of clusters with preferred length scales  

SciTech Connect

Ion-irradiation-induced modifications of a periodic Pt/C multilayer system containing a small amount of Fe have been analyzed by transmission electron microscopy and grazing incidence x-ray diffraction (GIXRD) studies. The multilayer stack with 16 Pt/C layer pairs (period of 4.23 nm) was fabricated on a glass substrate. A 2 MeV Au{sup 2+} ion beam was rastered on the sample to obtain uniformly irradiated strips with fluences from 1x10{sup 14} to 1x10{sup 15} ions/cm{sup 2}. Ion irradiation has been found to cause preferential migration of Fe towards Pt layers [Bera et al., Nucl. Instrum. Methods Phys. Res. B 212, 530 (2003)]. Cross-sectional transmission electron microscopy (XTEM) shows considerable atomic redistribution for irradiation at the highest ion fluence (1x10{sup 15} ions/cm{sup 2}). This structure is composed of small clusters. Phase separation and cluster formation processes are discussed. Periodic multilayers have periodicity only in the direction normal to the multilayer surface. However, Fourier transform (FT) of the XTEM images of the sample irradiated at the highest fluence shows extra off-normal Fourier components of superlattice periodicities arising due to ion irradiation. These extra spots in the FT are due to preferential length scales in intercluster separation in three dimensions. With a proper understanding of this phenomenon it may be possible to fabricate useful three-dimensional self-assembled structures of nanoclusters. Our high resolution transmission electron microscopy and GIXRD results reveal the formation of an FePt alloy. As FePt is a magnetic alloy, our observation raises the possibility of fabrication of ion-beam induced magnetic nanocluster lattices.

Bera, S.; Satpati, B.; Goswami, D. K.; Bhattacharjee, K.; Satyam, P. V.; Dev, B. N. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

2006-04-01

14

Deformation and material removal in a nanoscale multi-layer thin film solar panel using nanoscratch  

Microsoft Academic Search

Amorphous Si thin film solar panels are multi-layer structures consisting of nanometric layers of hard and brittle materials. The deformation and material removal characteristics of the panel cross-section were investigated using nano-mechanical testing. Nanoindentation and nanoscratching were performed using indenters of various geometries at a range of loads. Atomic force microscopy and electron microscopy were used to study the resulting

Taro Sumitomo; Han Huang; Libo Zhou

2011-01-01

15

Enhancement of biocompatibility of metal implants by nanoscale tiN/NbN multilayer coatings.  

PubMed

Titanium nitride (TiN)/niobium nitride (NbN) nanostructured multilayer coatings were prepared by DC reactive magnetron sputtering method using the combination of a titanium and niobium target and an Ar-N2 mixture discharge gas on to 316L stainless steel substrates. The coatings showed a polycrystalline structure with (111) for TiN and (101) for NbN preferential growth. Raman spectroscopy measurements on the multilayer films exhibited the characteristic peaks at 212, 303, 458 and 578 cm-1. A higher hardness of 38 GPa was observed for TiN/NbN coatings. Electrochemical polarization tests were performed in simulated biological fluid solutions at 37 degreesC in order to determine and compare the corrosion behavior of the coated and uncoated 316L SS substrates. The TiN/NbN multilayer coatings could improve the corrosion resistance of 316L SS substrate. The bacterial culture experiments were performed and the bacteria treated samples were examined by epi fluorescence microscope measurements. PMID:23901475

Subramanian, B

2013-07-01

16

Microstructure and electrical transport property of Fe/Cu nanoscale multilayered materials  

NASA Astrophysics Data System (ADS)

The microstructures and electrical conductivity (?) at room temperature of Fe/Cu multilayered material, which was prepared by the electron-beam physical-vapor-deposition technique, were investigated to understand the dependence of ? on the bilayer thickness (?=dFe+dCu) and the sublayer thickness ratio (?=dFe/?), where d is the sublayer thickness. Satellite peaks in the x-ray diffraction spectra were observed, indicating a layered structure in the multilayered material. The specimen was polycrystalline, and the in-plane grain size is independent of the sublayer thickness. ? at a fixed ? increases with increasing ?, and keeps nearly constant when ? is larger than 30 nm. ? at a fixed ? decreases linearly with increasing ?. The size dependence of ? is explained using a model that takes into account scattering by the sublayer interfaces and the grain boundaries. The scattering at interfaces and grain boundaries is thought to be the dominant mechanism for the size dependence of ? on ? when dFe is smaller and larger, respectively, than the estimated electron mean free path in the Cu sublayer.

Jin, Xuesong; Zhou, Y.; Kim, C. O.; Lee, Y. P.; Xu, Huibin; Gong, S. K.

2002-05-01

17

Cast iron cutting with nano TiN and multilayer TiN-CrN coated inserts  

NASA Astrophysics Data System (ADS)

During the past decade great success has been achieved in the development of duplex and multilayer multi-functional surface systems. Among these surface systems outstanding properties have nanoscale multilayer coatings. Within the framework of the M3-2S project funded in the 7th European Framework Programme, several nanoscale multilayer coatings have been developed and investigated for experimental and industrial validation. This paper shows the performance of TiN and TiN/CrN nanoscale multilayer coatings on WC cutting inserts when machining GJL250 cast iron. The thin films have been deposited by cathodic arc evaporation in an industrial PVD system. The multilayer deposition characteristic and its properties are shown. The inserts have been investigated in systematic cutting experiments of cast iron bars on a turning machine specifically equipped for force measurements, accompanied by wear determination. Furthermore, equivalent experiments have been carried out on an industrial turning unit. Industrial validation criteria have been applied to assess the comparative performance of the coatings. The choice of the material and the machined parts is driven by an interest in automotive applications. The industrial tests show the need to further optimise the multi-scale modelling approach in order to reduce the lead time of the coating development as well as to improve simulation reliability.

Perucca, M.; Durante, S.; Semmler, U.; Rüger, C.; Fuentes, G. G.; Almandoz, E.

2012-09-01

18

Second-order nonlinear optical characteristics of nanoscale self-assembled multilayer organic films  

NASA Astrophysics Data System (ADS)

Ionically self-assembled monolayer (ISAM) films are typically an assemblage of oppositely charged polymers built layer by layer through Coulombic attraction utilizing an environmentally friendly process to form ordered structures that are uniform, molecularly smooth and physically robust. ISAM films have been shown to be capable of the noncentrosymmetric order requisite for a second-order nonlinear optical response with excellent temporal and thermal stability. However, such films fabricated with a nonlinear optical (NLO) polyanion result in significant cancellation of the chromophore orientations. This cancellation occurs by two mechanisms: competitive orientation due to the ionic bonding of the polymer chromophore with the subsequent polycation layer, and random orientation of the chromophores within the bulk of each polyanion layer. A reduction in film thickness accompanied by an increase in net polar ordering is one possible avenue to obtain the second-order susceptibility chi (2) necessary for practical application in electro-optic devices. In this thesis, we discuss the structural characteristics of ISAM films and explore a novel approach to obtain the desired characteristics for nonlinear optical response. This approach involves a hybrid covalent/ionic self-assembly technique which affords improved net dipole alignment and concentration of monomer chromophores in the film. This technique yields a substantial increase in chi(2) due to the preferential chromophore orientation being locked in place by a covalent bond to the preceding polycation layer. The films fabricated in this manner yield a chi(2) (56 x 10-9 esu) that substantially exceeds that of any known polymer-polymer ISAM film (˜0.3 x 10-9 esu). This covalent-hybrid ionically self-assembled multilayer (CHISAM) technique is demonstrated to result in films suitable for electro-optic devices, with measured electro-optic coefficient (14 pm/V) comparable to that of the inorganic crystal lithium niobate (30 pm/V). Thermal and temporal stability are important properties of electro-optic device implementation, and are demonstrated for CHISAM films. CHISAM films have remained stable at room temperature for more than 420 days, and suffered no loss of chi(2) when held at 80°C for 36 hours, followed by 150°C for 24 hours. Studies are also presented that demonstrate the ability to produce ISAM chi (2) films that are nearly one micron thick, and exhibit no evidence of a thickness limitation to the polar order. Analytical considerations for second-order NLO characterization of thick films are addressed in detail. The effect of absorption of the second harmonic wavelength and resonant enhancement of chi(2) are investigated, and it is demonstrated that accurate determination of chi(2) may be made for thick films and for films that absorb the second harmonic. The temporal and thermal stability of a variety of ISAM and CHISAM NLO films are examined in detail. In some cases, a decrease in the NLO response is observed at elevated temperature that is completely restored upon cooling. Studies are presented that suggest this effect is a result of thermally induced trans-to- cis isomerization of azo linkages in the NLO chromophores.

Neyman, Patrick J.

19

Optical multilayers with an amorphous fluoropolymer  

SciTech Connect

Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, together with other optical materials. A high reflector at 1064 run was made with ZnS and AF2400. An all-organic 1064-nm reflector was made from AF2400 and polyethylene. Oxide (HfO{sub 2}, SiO{sub 2}) compatibility was also tested. Each multilayer system adhered to itself. The multilayers were influenced by coating stress and unintentional temperature rises during PVD deposition.

Chow, R.; Loomis, G.E.; Lindsey, E.F.

1994-07-01

20

Characterization of nanoscale transformations in polyelectrolyte multilayers fabricated from plasmid DNA using laser scanning confocal microscopy in combination with atomic force microscopy.  

PubMed

Laser scanning confocal microscopy (LSCM) and atomic force microscopy (AFM) were used to characterize changes in nanoscale structure that occur when ultrathin polyelectrolyte multilayers (PEMs) are incubated in aqueous media. The PEMs investigated here were fabricated by the deposition of alternating layers of plasmid DNA and a hydrolytically degradable polyamine onto a precursor film composed of alternating layers of linear poly(ethylene imine) (LPEI) and sodium poly(styrene sulfonate) (SPS). Past studies of these materials in the context of gene delivery revealed transformations from a morphology that is smooth and uniform to one characterized by the formation of nanometer-scale particulate structures. We demonstrate that in-plane registration of LSCM and AFM images acquired from the same locations of films fabricated using fluorescently labeled polyelectrolytes allows the spatial distribution of individual polyelectrolyte species to be determined relative to the locations of topographic features that form during this transformation. Our results suggest that this physical transformation leads to a morphology consisting of a relatively less disturbed portion of film composed of polyamine and DNA juxtaposed over an array of particulate structures composed predominantly of LPEI and SPS. Characterization by scanning electron microscopy and energy-dispersive X-ray microanalysis provides additional support for this interpretation. The combination of these different microscopy techniques provides insight into the structures and dynamics of these multicomponent thin films that cannot be achieved using any one method alone, and could prove useful for the further development of these assemblies as platforms for the surface-mediated delivery of DNA. PMID:20155860

Fredin, Nathaniel J; Flessner, Ryan M; Jewell, Christopher M; Bechler, Shane L; Buck, Maren E; Lynn, David M

2010-09-01

21

Characterization of Nanoscale Transformations in Polyelectrolyte Multilayers Fabricated from Plasmid DNA Using Laser Scanning Confocal Microscopy in Combination with Atomic Force Microscopy  

PubMed Central

Laser scanning confocal microscopy (LSCM) and atomic force microscopy (AFM) were used to characterize changes in nanoscale structure that occur when ultrathin polyelectrolyte multilayers (PEMs) are incubated in aqueous media. The PEMs investigated here were fabricated by the deposition of alternating layers of plasmid DNA and a hydrolytically degradable polyamine onto a precursor film composed of alternating layers of linear poly(ethylene imine) (LPEI) and sodium poly(styrene sulfonate) (SPS). Past studies of these materials in the context of gene delivery revealed transformations from a morphology that is smooth and uniform to one characterized by the formation of nanometer-scale particulate structures. We demonstrate that in-plane registration of LSCM and AFM images acquired from the same locations of films fabricated using fluorescently labeled polyelectrolytes allows the spatial distribution of individual polyelectrolyte species to be determined relative to the locations of topographic features that form during this transformation. Our results suggest that this physical transformation leads to a morphology consisting of a relatively less disturbed portion of film composed of polyamine and DNA juxtaposed over an array of particulate structures composed predominantly of LPEI and SPS. Characterization by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) microanalysis provides additional support for this interpretation. The combination of these different microscopy techniques provides insight into the structures and dynamics of these multicomponent thin films that cannot be achieved using any one method alone, and that could prove useful for the further development of these assemblies as platforms for the surface-mediated delivery of DNA. PMID:20155860

Fredin, Nathaniel J.; Flessner, Ryan M.; Jewell, Christopher M.; Bechler, Shane L.; Buck, Maren E.; Lynn, David M.

2010-01-01

22

Optical multilayer films based on an amorphous fluoropolymer  

SciTech Connect

Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, and with other optical materials. A high reflector for 1064 nm light was made with ZnS and AF2400. An all-organic 1064 nm reflector was made from AF2400 and polyethylene. Oxide (HfO{sub 2} and SiO{sub 2}) compatibility with AF2400 was also tested. The multilayer morphologies were influenced by coating stress and unintentional temperature rises from the PVD process. Analysis by liquid nuclear magnetic resonance of the thin films showed slight compositional variations between the coating and starting materials of perfluorinated amorphous polymers.

Chow, R.; Loomis, G.E.; Ward, R.L. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

1996-01-01

23

PVD TBC experience on GE aircraft engines  

NASA Technical Reports Server (NTRS)

The higher performance levels of modern gas turbine engines present significant challenges in the reliability of materials in the turbine. The increased engine temperatures required to achieve the higher performance levels reduce the strength of the materials used in the turbine sections of the engine. Various forms of thermal barrier coatings (TBC's) have been used for many years to increase the reliability of gas turbine engine components. Recent experience with the physical vapor deposition (PVD) process using ceramic material has demonstrated success in extending the service life of turbine blades and nozzles. Engine test results of turbine components with a 125 micron (0.005 in) PVD TBC have demonstrated component operating temperatures of 56-83 C (100-150 F) lower than non-PVD TBC components. Engine testing has also revealed the TBC is susceptible to high angle particle impact damage. Sand particles and other engine debris impact the TBC surface at the leading edge of airfoils and fracture the PVD columns. As the impacting continues, the TBC erodes away in local areas. Analysis of the eroded areas has shown a slight increase in temperature over a fully coated area, however a significant temperature reduction was realized over an airfoil without TBC.

Maricocchi, Antonio; Bartz, Andi; Wortman, David

1995-01-01

24

PVD TBC experience on GE aircraft engines  

NASA Astrophysics Data System (ADS)

The higher performance levels of modern gas turbine engines present significant challenges in the reli-ability of materials in the turbine. The increased engine temperatures required to achieve the higher per-formance levels reduce the strength of the materials used in the turbine sections of the engine. Various forms of thermal barrier coatings have been used for many years to increase the reliability of gas turbine engine components. Recent experience with the physical vapor deposition process using ceramic material has demonstrated success in extending the service life of turbine blades and nozzles. Engine test results of turbine components with a 125 ?m (0.005 in.) PVD TBC have demonstrated component operating tem-peratures of 56 to 83 °C (100 to 150 °F) lower than non-PVD TBC components. Engine testing has also revealed that TBCs are susceptible to high angle particle impact damage. Sand particles and other engine debris impact the TBC surface at the leading edge of airfoils and fracture the PVD columns. As the impacting continues, the TBC erodes in local areas. Analysis of the eroded areas has shown a slight increase in temperature over a fully coated area ; however, a significant temperature reduc-tion was realized over an airfoil without TBC.

Maricocchi, A.; Bartz, A.; Wortman, D.

1997-06-01

25

PVD TBC experience on GE aircraft engines  

NASA Technical Reports Server (NTRS)

The higher performance levels of modern gas turbine engines present significant challenges in the reliability of materials in the turbine. The increased engine temperatures required to achieve the higher performance levels reduce the strength of the materials used in the turbine sections of the engine. Various forms of Thermal Barrier Coatings (TBC's) have been used for many years to increase the reliability of gas turbine engine components. Recent experience with the Physical Vapor Deposition (PVD) process using ceramic material has demonstrated success in extending the service life of turbine blades and nozzles. Engine test results of turbine components with a 125 micrometer (0.005 in) PVD TBC have demonstrated component operating temperatures of 56-83 C (100-150 F) lower than uncoated components. Engine testing has also revealed the TBC is susceptible to high angle particle impact damage. Sand particles and other engine debris impact the TBC surface at the leading edge of airfoils and fracture the PVD columns. As the impacting continues the TBC erodes away in local areas. Analysis of the eroded areas has shown a slight increase in temperature over a fully coated area, however, a significant temperature reduction was realized over an airfoil without any TBC.

Bartz, A.; Mariocchi, A.; Wortman, D. J.

1995-01-01

26

Protection of yttria-stabilized zirconia for dental applications by oxidic PVD coating.  

PubMed

In this study, the application of transparent physical vapor deposition (PVD) coatings on zirconia ceramics was examined as an approach to retard the low-temperature degradation of zirconia for dental applications. Transparent monolayers of titanium oxide (TixOy) and multilayers consisting of titanium oxide-alumina-titanium oxide (TixOy-AlxOy-TixOy) were deposited onto standardized discs of 3Y-TZP using magnetron sputtering. Using X-ray photospectroscopy and time-of-flight secondary-ion mass spectrometry, the compositions of the coatings were verified, and an approximate thickness of 50nm for each type of coating was ascertained. After aging the coated and uncoated samples in water vapor at 134°C and 3bar for 4, 8, 16, 32, 64 and 128h, the monoclinic phase content was determined using X-ray diffraction, and its impact on mechanical properties was assessed in biaxial flexural strength tests. In addition, the depth of the transformation zone was measured from scanning electron microscopy images of the fracture surfaces of hydrothermally aged samples. The results revealed that the tetragonal-to-monoclinic phase transformation of the zirconia ceramic was retarded by the application of PVD coatings. During the first stages of aging, the coated samples exhibited a significantly lower monoclinic phase content than the uncoated samples and, after 128h of aging, showed a transformation zone which was only ?12-15?m thick compared to ?30?m in the control group. Biaxial flexural strength decreased by ?10% during aging and was not influenced by the application of a PVD coating. PMID:25278443

Hübsch, C; Dellinger, P; Maier, H J; Stemme, F; Bruns, M; Stiesch, M; Borchers, L

2015-01-01

27

Controlling light with plasmonic multilayers  

NASA Astrophysics Data System (ADS)

Recent years have seen a new wave of interest in layered media - namely, plasmonic multilayers - in several emerging applications ranging from transparent metals to hyperbolic metamaterials. In this paper, we review the optical properties of such subwavelength metal-dielectric multilayered metamaterials and describe their use for light manipulation at the nanoscale. While demonstrating the recently emphasized hallmark effect of hyperbolic dispersion, we put special emphasis to the comparison between multilayered hyperbolic metamaterials and more broadly defined plasmonic-multilayer metamaterials A number of fundamental electromagnetic effects unique to the latter are identified and demonstrated. Examples include the evolution of isofrequency contour shape from elliptical to hyperbolic, all-angle negative refraction, and nonlocality-induced optical birefringence. Analysis of the underlying physical causes, which are spatial dispersion and optical nonlocality, is also reviewed. These recent results are extremely promising for a number of applications ranging from nanolithography to optical cloaking.

Orlov, Alexey A.; Zhukovsky, Sergei V.; Iorsh, Ivan V.; Belov, Pavel A.

2014-06-01

28

Multilayer dielectric narrow band mangin mirror  

NASA Astrophysics Data System (ADS)

The design of multilayer stack of dielectric films for narrow band mirror is developed using thin film coating software. The proposed design is materialized by employing thin film coating (PVD) method and reflectance in narrow band spectrum range is achieved. Thickness of high and low refractive index material is taken precisely up to nanometer level. The curved coated substrate is cemented with another K9 matching substrate that forms a Mangin mirror for wavelength 650nm. Narrow band mirrors with reflectivity more than 90% has been produced by properly stacking of 21 layers and advantage of the use of this type of mirror as an interference filter is discussed.

Ahmed, K.; Khan, A. N.; Rauf, A.; Gul, A.

2014-06-01

29

Conceptualizing Nanoscale  

NSDL National Science Digital Library

One strategy for enhancing students' understanding of nanoscale is to shift students' existing understandings of relative scale by helping them conceptually transport their strongest scale benchmark--themselves--into the nanoscale world. This article describes a set of activities to scaffold high school students' nanoscsale conceptions and to help them appreciate the scale at which nanotechnology operates, both in a relative and an absolute sense.

Tretter, Thomas

2006-12-01

30

Cementation as a method of observing defects in PVD coatings  

Microsoft Academic Search

The cementation test as previously used to investigate defects in single metal nitride PVD coatings has been extended to the study of the new generation of mixed nitride coatings by its application to the study of defects in TiAlN coatings. Copper cementation tests carried out in a solution containing 0.1 g 1?1 of copper at pH 1.1 showed that the

P. Ernst; A. Earnshaw; I. P. Wadsworth; G. W. Marshall

1997-01-01

31

Nanoscale potentiometry  

PubMed Central

Potentiometric sensors share unique characteristics that set them apart from other electrochemical sensors. Potentiometric nanoelectrodes have been reported and successfully used for many decades, and we review these developments. Current research chiefly focuses on nanoscale films at the outer or the inner side of the membrane, with outer layers for increasing biocompatibility, expanding the sensor response, or improving the limit of detection (LOD). Inner layers are mainly used for stabilizing the response and eliminating inner aqueous contacts or undesired nanoscale layers of water. We also discuss the ultimate detectability of ions with such sensors and the power of coupling the ultra-low LODs of ion-selective electrodes with nanoparticle labels to give attractive bioassays that can compete with state-of-the-art electrochemical detection. PMID:19122854

Bakker, Eric; Pretsch, Ernö

2008-01-01

32

Nanoscale Wet Etching of Physical-Vapor-Deposited Titanium Nitride and Its Application to Sub-30-nm-Gate-Length Fin-Type Double-Gate Metal-Oxide-Semiconductor Field-Effect Transistor Fabrication  

NASA Astrophysics Data System (ADS)

The nanoscale wet etching of physical-vapor-deposited (PVD) titanium nitride (TiN) and its application to sub-30-nm-gate-length fin-type double-gate metal-oxide-semiconductor field-effect transistor (FinFET) fabrication are systematically investigated. It is experimentally found that PVD-TiN side-etching depth can be controlled to be one-half of PVD-TiN thickness with precise time control using an ammonium hydroxide (NH4OH) : hydrogen peroxide (H2O2) : deionized water (H2O) = 1 : 2 : 5 solution at 60 °C. Using the developed nanoscale PVD-TiN wet etching technique, sub-30-nm-physical-gate-length FinFETs, 100-nm-tall fin-channel complementary MOS (CMOS) inverters and static random access memory (SRAM) half-cells have successfully been fabricated and demonstrated. These experimental results indicate that the developed nanoscale PVD-TiN wet etching technique is very useful for tall fin-channel CMOS fabrication.

Yongxun Liu,; Takahiro Kamei,; Kazuhiko Endo,; Shinichi O'uchi,; Junichi Tsukada,; Hiromi Yamauchi,; Tetsuro Hayashida,; Yuki Ishikawa,; Takashi Matsukawa,; Kunihiro Sakamoto,; Atsushi Ogura,; Meishoku Masahara,

2010-06-01

33

Novel porous separator based on PVdF and PE non-woven matrix for rechargeable lithium batteries  

Microsoft Academic Search

The novel porous separator based on PVdF (poly(vinylidene fluoride)) and a PE (polyethylene) non-woven matrix is prepared by coating PVdF\\/NMP solution on the matrix (NMP: N-methyl-2-pyrrolidone). The pore structure is generated in the PVdF region by phase inversion of the polymer solution. The PE non-woven matrix imparts mechanical strength and a thermal shut-down property to the separator, while the PVdF

Yong Min Lee; Jun-Woo Kim; Nam-Soon Choi; Je An Lee; Wan-Ho Seol; Jung-Ki Park

2005-01-01

34

EVOLUTION OF POROSITY AND TEXTURE IN THERMAL BARRIER COATINGS GROWN BY EB-PVD  

E-print Network

EVOLUTION OF POROSITY AND TEXTURE IN THERMAL BARRIER COATINGS GROWN BY EB-PVD Scott G. Terry, 93106-5050 Abs tract The pattern and distribution of porosity in the columnar microstructure of thermal to advance the understanding of the evolution of porosity during EB-PVD growth, as well as its relationship

Clarke, David R.

35

Application of PVD methods to solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

In this paper, attention is paid to the application of such a method of vacuum physical vapor deposition (PVD) as magnetron sputtering for fabrication of a solid oxide fuel cell (SOFC) materials and structures. It is shown that the YSZ (yttria-stabilized zirconia) electrolyte and Ni-YSZ anode layers with required thickness, structure and composition can be effectively formed by PVD methods. The influence of parameters of pulsed power magnetron discharge on the deposition rate and the microstructure of the obtained YSZ electrolyte films were investigated. It is shown that the deposition rate of the oxide layers by magnetron sputtering can be significantly increased by using asymmetric bipolar power magnetrons, which creates serious prerequisites for applying this method on the industrial scale. Porous Ni-YSZ anode films were obtained by reactive co-sputtering of Ni and Zr-Y targets and subsequent reduction in the H2 atmosphere at a temperature of 800 °C. The Ni-YSZ films comprised small grains and pores of tens of nanometers.

Solovyev, A. A.; Sochugov, N. S.; Rabotkin, S. V.; Shipilova, A. V.; Ionov, I. V.; Kovalchuk, A. N.; Borduleva, A. O.

2014-08-01

36

Exchange bias in nanoscale antidot arrays D. Tripathy,1  

E-print Network

Exchange bias in nanoscale antidot arrays D. Tripathy,1 A. O. Adeyeye,1,a and N. Singh2 180Fe20 30 nm /Ir75Mn25 30 nm /Cu 2 nm multilayer antidot arrays. The antidot arrays exhibit to their technological applica- tions in magnetoresistive read heads and magnetic random access memories.6 The constant

Adeyeye, Adekunle

37

EDITORIAL: Nanoscale metrology Nanoscale metrology  

NASA Astrophysics Data System (ADS)

This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2010 seminar held in Brno, Czech Republic. It was the 5th Seminar on Nanoscale Calibration Standards and Methods and the 9th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Czech Metrology Institute (CMI) and the Nanometrology Group of the Technical Committee-Length of EURAMET. There were two workshops that were integrated into NanoScale 2010: first a workshop presenting the results obtained in NANOTRACE, a European Metrology Research Project (EMRP) on displacement-measuring optical interferometers, and second a workshop about the European metrology landscape in nanometrology related to thin films, scanning probe microscopy and critical dimension. The aim of this workshop was to bring together developers, applicants and metrologists working in this field of nanometrology and to discuss future needs. For more information see www.co-nanomet.eu. The articles in this special issue of Measurement Science and Technology cover some novel scientific results. This issue can serve also as a representative selection of topics that are currently being investigated in the field of European and world-wide nanometrology. Besides traditional topics of dimensional metrology, like development of novel interferometers or laser stabilization techniques, some novel interesting trends in the field of nanometrology are observed. As metrology generally reflects the needs of scientific and industrial research, many research topics addressed refer to current trends in nanotechnology, too, focusing on traceability and improved measurement accuracy in this field. While historically the most studied standards in nanometrology were related to simple geometric structures like step heights or 1D or 2D gratings, now we are facing tasks to measure 3D structures and many unforeseen questions arising from interesting physical properties of nanoparticles, nanotubes, quantum dots and similar fascinating objects. Currently there is a high level of interest in characterization of nanoparticles since they are increasingly encountered in science, technology, life sciences and even everyday life. Quantitative characterization of nanoparticles has been the subject of many discussions and some recent work over the last couple of years, and both scanning probe microscopy and scanning or transmission electron microscopy characterization of nanoparticles are presented here. There is also a continuous need for improvement of scanning probe microscopy that is a basic tool for nanometrology. Increasing thermal stability, scanning speed and tip stability, improving traceability and reducing uncertainty are all areas being addressed. As scanning probe microscopy is essentially based on force measurements in the nano- and piconewton range, we take notice of large developments, both theoretical and experimental, in the field of traceable measurements of nanoscale forces. This will greatly increase the understanding and quantification of many basic phenomena in scanning probe microscopy. Finally, we observe that high resolution techniques for acquiring more than just morphology are slowly shifting from purely qualitative tools to well defined quantitative methods. Lack of simple and reliable chemical identification in scanning probe microscopy is compensated by many other local probing methods seen in commercial microscopes, like scanning thermal microscopy or the Kelvin probe technique. All these methods still require underpinning with theoretical and experimental work before they can become traceable analytical methods; however, the increased interest in the metrology community gives rise to optimism in this field. The production of this issue involved considerable effort from many contributors. We would like to thank all the authors for their contributions, the referees for their time spent reviewing the contributions and their valuable comments, and the whole Editorial Board of Measurement Science and Tec

Klapetek, P.; Koenders, L.

2011-09-01

38

Elastic analysis of an inhomogeneous quantum dot in multilayered semiconductors using a boundary element method  

E-print Network

Elastic analysis of an inhomogeneous quantum dot in multilayered semiconductors using a boundary examine the elastostatic field due to a buried quantum dot QD in multilayered semiconductors using quasizero- dimensional dots or quantum dots QDs and quasione- dimensional wires on the nanoscale

Pan, Ernie

39

Characterization of PVD Lumogen films for wavelength conversion applications  

NASA Astrophysics Data System (ADS)

Lumogen Yellow S0790 is a commercial azomethine based pigment and is used for enhancing CCD devices for detecting ultraviolet radiation. In this work we report on the crystal structure and morphology of the raw material, as-deposited and post-annealed films, as well as the influence these have on the subsequent optical properties. Our measurements of physical vapour deposited (PVD) Lumogen films indicate that commercial Lumogen powder is crystalline in its as-received state, with a melting point of 273.3°C and boiling point of 328.6°C. Furthermore, we have found that as-deposited films on room temperature substrates possess an inherent crystalline structure, which has not been reported previously, but also that the material"s structure changes into a completely different crystalline form upon annealing for 90 hours at 80°C.

Deslandes, A.; Wedding, A. B.; Clarke, Steven R.; Matisons, J. G.; Quinton, Jamie S.

2005-02-01

40

Macroscale vs. Nanoscale  

NSDL National Science Digital Library

In this colorful, interactive object, learners examine how materials on the nanoscale compare with those on the macroscale. The focus is on the difference between macroscale and nanoscale gold in both color and melting point.

2010-11-23

41

Performance of PVD-Coated Carbide Tools When Machining Ti6Al4V©  

Microsoft Academic Search

This work investigates the performance of TiN and TiN\\/TiCN\\/TiN physical vapor deposition (PVD)-coated carbide tools in continuous turning of Ti-6Al-4V. Significant improvement in tool life was achieved when machining Ti-6Al-4V with both PVD-coated tools under the optimum cutting conditions. Notching at the depth of cut (DOC) was suppressed and flank wear, chipping and flaking of tool material on the rake

Z. M. Wang; E. O. Ezugwu

1997-01-01

42

The influence of humidity on the fretting behaviour of PVD TiN coatings  

Microsoft Academic Search

The influence of the relative humidity (RH) in ambient air on the friction and wear behaviour of PVD TiN coatings subjected to contact vibrations against corundum and bearing steel (100Cr6) counterbodies has been investigated. The fretting experiments were performed in the gross-slip regime on TiN coatings produced by three different PVD processes. The results indicate two basic friction characteristics. At

H. Mohrbacher; B. Blanpain; J.-P. Celis; J. R. Roos

1995-01-01

43

Improved Thermal Cycling Durability of Thermal Barrier Coatings Manufactured by PS-PVD  

NASA Astrophysics Data System (ADS)

The plasma spray-physical vapor deposition (PS-PVD) process is a promising method to manufacture thermal barrier coatings (TBCs). It fills the gap between traditional thermal spray processes and electron beam physical vapor deposition (EB-PVD). The durability of PS-PVD manufactured columnar TBCs is strongly influenced by the compatibility of the metallic bondcoat (BC) and the ceramic TBC. Earlier investigations have shown that a smooth BC surface is beneficial for the durability during thermal cycling. Further improvements of the bonding between BC and TBC could be achieved by optimizing the formation of the thermally grown oxide (TGO) layer. In the present study, the parameters of pre-heating and deposition of the first coating layer were investigated in order to adjust the growth of the TGO. Finally, the durability of the PS-PVD coatings was improved while the main advantage of PS-PVD, i.e., much higher deposition rate in comparison to EB-PVD, could be maintained. For such coatings, improved thermal cycling lifetimes more than two times higher than conventionally sprayed TBCs, were measured in burner rigs at ~1250 °C/1050 °C surface/substrate exposure temperatures.

Rezanka, S.; Mauer, G.; Vaßen, R.

2014-01-01

44

Nanoscale thermal probing  

PubMed Central

Nanoscale novel devices have raised the demand for nanoscale thermal characterization that is critical for evaluating the device performance and durability. Achieving nanoscale spatial resolution and high accuracy in temperature measurement is very challenging due to the limitation of measurement pathways. In this review, we discuss four methodologies currently developed in nanoscale surface imaging and temperature measurement. To overcome the restriction of the conventional methods, the scanning thermal microscopy technique is widely used. From the perspective of measuring target, the optical feature size method can be applied by using either Raman or fluorescence thermometry. The near-field optical method that measures nanoscale temperature by focusing the optical field to a nano-sized region provides a non-contact and non-destructive way for nanoscale thermal probing. Although the resistance thermometry based on nano-sized thermal sensors is possible for nanoscale thermal probing, significant effort is still needed to reduce the size of the current sensors by using advanced fabrication techniques. At the same time, the development of nanoscale imaging techniques, such as fluorescence imaging, provides a great potential solution to resolve the nanoscale thermal probing problem. PMID:22419968

Yue, Yanan; Wang, Xinwei

2012-01-01

45

PvdP Is a Tyrosinase That Drives Maturation of the Pyoverdine Chromophore in Pseudomonas aeruginosa  

PubMed Central

The iron binding siderophore pyoverdine constitutes a major adaptive factor contributing to both virulence and survival in fluorescent pseudomonads. For decades, pyoverdine production has allowed the identification and classification of fluorescent and nonfluorescent pseudomonads. Here, we demonstrate that PvdP, a periplasmic enzyme of previously unknown function, is a tyrosinase required for the maturation of the pyoverdine chromophore in Pseudomonas aeruginosa. PvdP converts the nonfluorescent ferribactin, containing two iron binding groups, into a fluorescent pyoverdine, forming a strong hexadentate complex with ferrous iron, by three consecutive oxidation steps. PvdP represents the first characterized member of a small family of tyrosinases present in fluorescent pseudomonads that are required for siderophore maturation and are capable of acting on large peptidic substrates. PMID:24816606

Nadal-Jimenez, Pol; Koch, Gudrun; Reis, Carlos R.; Muntendam, Remco; Raj, Hans; Jeronimus-Stratingh, C. Margot; Cool, Robbert H.

2014-01-01

46

Pyoverdine and beyond: PvdS dependent gene regulation in Pseudomonas syringae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The extracytoplasmic function (ECF) sigma factor PvdS regulates the expression of genes in Pseudomonas aeruginosa encoding virulence factors and the biosynthesis and transport of pyoverdine, a siderophore involved in iron acquisition. The production of pyoverdine is a distinctive trait of the fluor...

47

PVdF-Clay Nanocomposite Gel Polymer Electrolytes For Li-Ion Batteries  

Microsoft Academic Search

In the present work, nanocomposite polymer electrolytes based on intercalation of PVdF polymer into the galleries of organically modified montmorillonite (MMT) clays has been investigated. XRD and TEM results display the formation of partially exfoliated nanocomposites. Ac impedance analysis reveal that the ionic conductivity of the nanocomposite gel polymer electrolytes increases with the increase in clay loading and attains a

A. Kumar; M. Deka

2011-01-01

48

Cutting performance increasing in gear hobbing by means of HSS hobs, coated with effective PVD films  

Microsoft Academic Search

Coated tools experience a rapid development due to the increased demands towards cutting performance improvement and production cost diminishing. In order to meet corresponding requirements in gear manufacturing, impressive developments, among others, in the area of coating technology, have been realized. In order to investigate the effectiveness of various innovative PVD films, fly hobbing wear experiments in individual generating positions

K.-D. Bouzakis; S. Kombogiannis; O. Friderikos; J. Anastopoulos

49

Electrical Properties of Gamma Irradiated PVdF Based Polymer Electrolytes  

SciTech Connect

The effect of different doses of {gamma}-irradiation on the conductivity of PVdF-LiPF{sub 6} solid polymer electrolyte (SPE) was investigated at room temperature. The dielectric constant and loss are seen to increase with increasing radiation doses.

Ayoub, N.; Amin, Y. M.; Arof, A. K. [Physics Department, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2010-07-07

50

Investigation of PVD arc coatings on polyamide fabrics 1 Presented at the ICMCTF 2000 conference. 1  

Microsoft Academic Search

In contrast to conventional metallisation procedures for textile fibres and fabrics, physical vapour deposition (PVD) technologies allow the production of a defined structure of thin films on most fabric surfaces. This permits many new applications, especially for so-called technical textiles. The generation of properties such as supreme anti-static; electrical conductivity; shielding against electromagnetic radiation, protection against heat rays, chemical resistance,

Yvette Dietzel; Waldemar Przyborowski; Günter Nocke; Peter Offermann; Frank Hollstein; Jürgen Meinhardt

2000-01-01

51

Nanoscale construction with DNA  

NASA Astrophysics Data System (ADS)

The programmability of DNA makes it an attractive material for constructing intricate nanoscale shapes. One method for creating these structures is DNA origami, in which a multiple-kilobase single-stranded ``scaffold'' is folded into a custom nanoscale shape by interacting with hundreds of short oligonucleotide ``staple'' strands. I will talk about our efforts to realize demand-meeting applications of this method, including our recent development of nanoscale devices to mimic cell-signaling stimulation carried out by our own immune systems.

Douglas, Shawn

2013-03-01

52

CrN\\/NbN coatings deposited by HIPIMS: A preliminary study of erosion–corrosion performance  

Microsoft Academic Search

Nanoscale CrN\\/NbN multilayer PVD coatings have exhibited resistance to erosion–corrosion. However growth defects (under dense structures and droplets) in the coating produced by some deposition technologies reduce the ability to offer combined erosion–corrosion resistance. In this work a novel High Power Impulse Magnetron Sputtering (HIPIMS) technique has been utilised to pretreat substrates and deposit dense nanoscale CrN\\/NbN PVD coatings (HIPIMS–HIPIMS

Y. P. Purandare; A. P. Ehiasarian; M. M. Stack; P. Eh. Hovsepian

2010-01-01

53

Microstructural, mechanical and oxidation features of NiCoCrAlY coating produced by plasma activated EB-PVD  

NASA Astrophysics Data System (ADS)

NiCoCrAlY coatings produced by electron beam-physical vapor deposition (EB-PVD) have been extensively used as the oxidation resistance coatings or suitable bond coats in thermal barrier coating (TBC) system. However, the inherent imperfections caused by EB-PVD process degrade the oxidation resistance of the coatings. In the present work, NiCoCrAlY coatings were creatively produced by plasma activated electron beam-physical vapor deposition (PA EB-PVD). The novel coatings showed a terraced substructure on the surface of each grain due to the increased energy of metal ions and enhanced mobility of adatoms. Also a strong (1 1 1) crystallographic texture of ?/?' grains was observed. The toughness of the coatings got remarkably improved compared with the coatings deposited by conventional EB-PVD and the oxidation behavior at 1373 K showed that the novel coatings had excellent oxidation resistance. The possible mechanism was finally discussed.

He, Jian; Guo, Hongbo; Peng, Hui; Gong, Shengkai

2013-06-01

54

High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition  

NASA Technical Reports Server (NTRS)

Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

2014-01-01

55

Nano-scale adhesion in multilayered drug eluting stents.  

PubMed

Using stainless steel 316L for drug-eluting stents needs specific surface finishing due to corrosion phenomena that take place on the metal surface upon prolonged contact with human tissue. Poly (o-chloro-p-xylylene) (Parylene C) is one of the inert and biocompatible materials that are used for 316L coating with ?-methacryloxypropyltrimethoxysilane as an adhesion promoter. In this study, a combination of atomic force microscopy experiments and contact theories have been used to quantify the work of adhesion between parylene C/316L and silane added parylene C/316L. An atomistic simulation has been used, first, to investigate and compare the adhesion at the room temperature with the experiments and then, to investigate the effect of aqueous environment with higher temperature, inside the body, on the adhesion between layers in the structure of drug eluting stent. The simulation results of simplified model for 316L are in good agreement with the experimental results and suggest that the week affiliation between this polymer and 316L is mainly due to Van der Waals interactions. The effect of temperature on the adhesion is found to be regressive and as the water molecules permeate the polymer the adhesion decreases. They also imply that the effect of silane on the adhesion between parylene C and steel is modest. PMID:23237875

Youssefian, Sina; Rahbar, Nima

2013-02-01

56

Transport-Controlling Nanoscale Multilayers for Biomedical Devices  

E-print Network

: (a) PSS/PAH; and (b) PAA/PAH alternate adsorption in 0.5 M NaCl aqueous solution. ....... 19 Figure 8. Scanning electron microscope images of nanofilms: (a) bare alumina substrate; (b) [PSS/PAH]6.5; and (c) [PAA/PAH]6.5. Samples were coated.../PAH]15 film constructed with different NaCl concentrations (0, 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 M) during the LbL. Error bars indicate 95% confidence intervals (n=15). ...................................... 32 Figure 14. Contact angles...

Park, Jae Bum

2012-10-19

57

Multilayer Insulation Material Guidelines  

NASA Technical Reports Server (NTRS)

Multilayer Insulation Material Guidelines provides data on multilayer insulation materials used by previous spacecraft such as Spacelab and the Long-Duration Exposure Facility and outlines other concerns. The data presented in the document are presented for information only. They can be used as guidelines for multilayer insulation design for future spacecraft provided the thermal requirements of each new design and the environmental effects on these materials are taken into account.

Finckenor, M. M.; Dooling, D.

1999-01-01

58

Functional expression and activity of the recombinant antifungal defensin PvD1r from Phaseolus vulgaris L. (common bean) seeds  

PubMed Central

Background Defensins are basic, cysteine-rich antimicrobial peptides that are important components of plant defense against pathogens. Previously, we isolated a defensin, PvD1, from Phaseolus vulgaris L. (common bean) seeds. Results The aim of this study was to overexpress PvD1 in a prokaryotic system, verify the biologic function of recombinant PvD1 (PvD1r) by comparing the antimicrobial activity of PvD1r to that of the natural defensin, PvD1, and use a mutant Candida albicans strain that lacks the gene for sphingolipid biosynthesis to unravel the target site of the PvD1r in C. albicans cells. The cDNA encoding PvD1, which was previously obtained, was cloned into the pET-32 EK/LIC vector, and the resulting construct was used to transform bacterial cells (Rosetta Gami 2 (DE3) pLysS) leading to recombinant protein expression. After expression had been induced, PvD1r was purified, cleaved with enterokinase and repurified by chromatographic steps. N-terminal amino acid sequencing showed that the overall process of the recombinant production of PvD1r, including cleavage with the enterokinase, was successful. Additionally, modeling revealed that PvD1r had a structure that was similar to the defensin isolated from plants. Purified PvD1 and PvD1r possessed inhibitory activity against the growth of the wild-type pathogenic yeast strain C. albicans. Both defensins, however, did not present inhibitory activity against the mutant strain of C. albicans. Antifungal assays with the wild-type C. albicans strains showed morphological changes upon observation by light microscopy following growth assays. PvD1r was coupled to FITC, and the subsequent treatment of wild type C. albicans with DAPI revealed that the labeled peptide was intracellularly localized. In the mutant strain, no intracellular labeling was detected. Conclusion Our results indicate that PvD1r retains full biological activity after recombinant production, enterokinase cleavage and purification. Additionally, our results from the antimicrobial assay, the microscopic analysis and the PvD1r-FITC labeling assays corroborate each other and lead us to suggest that the target of PvD1 in C. albicans cells is the sphingolipid glucosylceramide. PMID:24690228

2014-01-01

59

Biomedical applications of polypeptide multilayer nanofilms and microcapsules  

NASA Astrophysics Data System (ADS)

The past few years have witnessed considerable growth in synthetic polymer chemistry and physics, biomaterials science, and nano-scale engineering. Research on polypeptide multilayer films, coatings, and microcapsules is located at the intersection of these areas and are promising materials for applications in medicine, biotechnology, environmental science. Most envisioned applications of polypeptide multilayers have a biomedical bent. This dissertation on polypeptide multilayer film applications covers key points of polypeptides as materials, means of polymer production, film preparation, film characterization methods, and key points of current research in basic science. Both commercial and designed peptides have been used to fabricate films for in-vitro applications such as antimicrobial coatings and cell culture coatings and also microcapsules for drug delivery applications. Other areas of product development include artificial red blood cells, anisotropic coatings, enantioselective membranes, and artificial viruses.

Rudra, Jai Simha S.

60

Multilayer composite photonic bandgap fibers  

E-print Network

Materials and fabrication techniques are developed that lead to the successful fabrication of multilayer composite photonic bandgap fibers. The pertinent background in electromagnetic theory of multilayer dielectric mirrors ...

Hart, Shandon D. (Shandon Dee), 1978-

2004-01-01

61

Cutting performance of PVD-coated carbide and CBN tools in hardmilling  

Microsoft Academic Search

In this study, cutting performance of CBN tools and PVD-coated carbide tools in end-milling of hardened steel was investigated. In high-speed dry hardmilling, two types of CBN tools were applied: the CBN-rich type and an ordinary one. In the case of relatively low-speed milling, on the other hand, a few coated carbide tools were selected where four kinds of coating

Masato Okada; Akira Hosokawa; Ryutaro Tanaka; Takashi Ueda

2011-01-01

62

Characterization of ceramic PVD thin films on AZ31 magnesium alloys  

Microsoft Academic Search

Ceramic thin films have been widely used to protect the metal substrate as coatings in the past years. In order to improve the poor corrosion resistance of AZ31 magnesium alloy, the study in this paper used the electron beam evaporation method to prepare ceramic PVD films on its surface with TiO2 and Al2O3 as donors, respectively. Atomic force microscopy (AFM),

Guosong Wu; Xiaoqin Zeng; Wenbin Ding; Xingwu Guo; Shoushan Yao

2006-01-01

63

PVD Coating of Mg–AZ31 by Thin Layer of Al and Al–Si  

Microsoft Academic Search

Although magnesium alloys have the advantage of high specific strength, they have poor atmospheric corrosion resistance. An\\u000a important method of improving the corrosion resistance is by applying a coating layer. In this work, the physical vapor deposition\\u000a (PVD) technique is used for coating a magnesium (Mg) AZ31 sheet substrate with a thin layer of high purity aluminum (Al) and\\u000a Al–12.6%

Mohamed A. Taha; Nahed A. El-Mahallawy; Rawia M. Hammouda; Sherif I. Nassef

2010-01-01

64

Nanomechanical study of thin film nanocomposite and PVD thin films on polymer substrates for optical applications  

NASA Astrophysics Data System (ADS)

The mechanical properties of ultrathin (<120 nm) films differ substantially from the bulk properties of the material and are also strongly substrate dependent. We compare the properties of two differing film systems; a high particle loading nanocomposite of silica and a multiple layer physical vapour deposition (PVD) coating by nanoindentation, nano-scratch and nano-impact followed by structural analysis. The work is undertaken on hardcoated polymer substrates and uses two types of anti-reflection coatings as test systems. The nanocomposite film comprises of a high (>50%) loading of silica nanoparticles in an inorganic binder, which demonstrates significant flex and elastic recovery whereas PVD films are subject to brittle failure even at low applied loads. Failure of the nanocomposite film, with the exception of minor plastic deformation, does not occur until the underlying substrate fails. Although the PVD film has a greater hardness than the nanocomposite, failure occurs at lower loads due to a number of toughness reducing factors including reduced modulus, modulus mismatch with the substrate and film thickness. The resistance of ultrathin films to external mechanical stresses is therefore related to a number of factors and not simply to film hardness, the most important of which are film structure and film mechanical matching to the substrate.

Moghal, Jonathan; Bird, Andrew; Harris, Adrian H.; Beake, Ben D.; Gardener, Martin; Wakefield, Gareth

2013-12-01

65

Nanoscale Strain Metrology SEMICONDUCTORS  

E-print Network

nanodevices by developing novel methods to measure and model strain with nanoscale resolution hinges on accurate prediction and measurement of strain at unprecedented length scales. Objective Impact for Semiconductors, 2007). Novel tools for measuring strain will enable more efficient process development, more

66

Crystallization under nanoscale confinement.  

PubMed

Classical crystal growth models posit that crystallization outcomes are determined by nuclei that resemble mature crystal phases, but at a critical size where the volume free energy of nuclei begins to offset the unfavorable surface free energy arising from the interface with the growth medium. Crystallization under nanoscale confinement offers an opportunity to examine nucleation and phase transformations at length scales corresponding to the critical size, at which kinetics and thermodynamics of nucleation and growth intersect and dramatic departures in stability compared to bulk crystals can appear. This tutorial review focuses on recent investigations of the crystallization of organic compounds in nanoporous matrices that effectively provide millions of nanoscale reactors in a single sample, ranging from controlled porous glass (CPG) beads to nanoporous block-copolymer monoliths to anodic aluminum oxide (AAO) membranes. Confinement of crystal growth in this manner provides a snapshot of the earliest stages of crystal growth, with insights into nucleation, size-dependent polymorphism, and thermotropic behavior of nanoscale crystals. Moreover, these matrices can be used to screen for crystal polymorphs and assess their stability as nanocrystals. The well-aligned cylindrical nanoscale pores of polymer monoliths or AAO also allow determination of preferred orientation of embedded nanocrystals, affording insight into the competitive nature of nucleation, critical sizes, and phase transition mechanisms. Collectively, these investigations have increased our understanding of crystallization at length scales that are deterministic while suggesting strategies for controlling crystallization outcomes. PMID:24081010

Jiang, Qi; Ward, Michael D

2014-04-01

67

Netlike knitting of polyelectrolyte multilayers on honeycomb-patterned substrate.  

PubMed

The pH-amplified exponential growth layer-by-layer (LBL) self-assembly process was directly performed on honeycomb-patterned substrate for achievement of "guided patterning" of polyelectrolyte multilayers. Polyethylenimine (PEI) and poly(acrylic acid) (PAA) were used as polyanions, and their pH were carefully tuned to achieve pH-enhanced exponential growth. Guided by underlying hexagonally patterned islandlike poly(dimethylsiloxane) (PDMS) arrays, the diffusive polyelectrolytes rapidly interweaved into linear, multilayered structures distributed along the grooves between the patterned protuberate and formed a regular network of multilayered film with uniform mesh size. Netlike "knitting" of polyelectrolyte multilayers on honeycomb-patterned substrate has been realized by following this procedure. Superhydrophobic surfaces could be readily obtained after several bilayers of LBL assembly (with thermal cross-linking and surface fluorination by chemical vapor deposition), indicating that successful fabrication of functional micro- and nanoscale hierarchical structures can be achieved. Both high- and low-adhesion superhydrophobic surfaces ("petal effect" and "lotus effect") can be obtained with different bilayers of assembly, proving that different levels of nano- to microstructural hierarchy can be realized using this method. Furthermore, we were able to get topographically asymmetric, free-standing, polyelectrolyte multilayer films in the case that we performed more than eight bilayers of assembly. This research reported template-directed LBL patterning assembly for the first time. It provides a beneficial exploration for the surface patterning technique for the LBL assembly process. PMID:20684559

Sun, Wei; Shen, Liyan; Wang, Jiaming; Fu, Ke; Ji, Jian

2010-09-01

68

Multilayer dielectric diffraction gratings  

DOEpatents

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

1999-05-25

69

Multilayer dielectric diffraction gratings  

DOEpatents

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

Perry, Michael D. (Livermore, CA); Britten, Jerald A. (Oakley, CA); Nguyen, Hoang T. (Livermore, CA); Boyd, Robert (Livermore, CA); Shore, Bruce W. (Livermore, CA)

1999-01-01

70

Preparation of a PVdF-HFP/polyethylene composite gel electrolyte with shutdown function for lithium-ion secondary battery  

NASA Astrophysics Data System (ADS)

In order to improve the safety of lithium-ion secondary battery, a PVdF-HFP/polyethylene (PE) composite gel electrolyte with thermal shutdown function was prepared as an internal safety device. The composite gel electrolyte consists of a PVdF-HFP polymer, PE thermoplastic resin, and 1.0 mol/dm 3 LiClO 4/PC+EC (or LiPF 6/GBL+EC) plasticizer. When the PE content is over 23 wt.%, the electrical impedance of the composite gel electrolyte can increase rapidly by several orders, around the melting point of PE (mp: 90 or 104-115°C). By the SEM observation it was found that the PE particles uniformly dispersed in the PVdF-HFP gel electrolyte could be fused and formed into a continuous film at or near the PE melting point. The continuous PE film exhibits an ability to cut off the ion diffusion between cathode and anode, thus preventing the cell from thermal runaway. Also, a three-layered film of pure PVdF-HFP gel/composite gel/pure PVdF-HFP with a higher ionic conductivity and good mechanical strength was prepared for assembling a coin-type lithium-ion cell.

Liu, Xingjiang; Kusawake, Hiroaki; Kuwajima, Saburo

71

Electroanalysis at the Nanoscale  

NASA Astrophysics Data System (ADS)

This article reviews the state of the art of silicon chip-based nanoelectrochemical devices for sensing applications. We first describe analyte mass transport to nanoscale electrodes and emphasize understanding the importance of mass transport for the design of nanoelectrode arrays. We then describe bottom-up and top-down approaches to nanoelectrode fabrication and integration at silicon substrates. Finally, we explore recent examples of on-chip nanoelectrodes employed as sensors and diagnostics, finishing with a brief look at future applications.

Dawson, Karen; O'Riordan, Alan

2014-06-01

72

Collaboration at the Nanoscale  

NSDL National Science Digital Library

The Maine ScienceCorps is a project sponsored by the National Science Foundation's (NSF) Graduate Teaching Fellows in K-12 Education (GK-12 ) program. Through this program, the University of Southern Maine's (USM) virology and transmission electron microscopy (TEM) research group provides high school teachers and students in rural areas with access to the nanoscale world of viruses. This article illustrates how access to the university research community's advanced technological resources can enrich science learning in high school classrooms.

Jamison, Jennifer L.; Moulton, Karen D.; Duboise, S. M.

2009-04-01

73

Science Sampler: Nanoscale in perspective  

NSDL National Science Digital Library

Nanoscale science is a growing field, and to appreciate the work of scientists in this field, it is important for students to understand the scale of work being done. This activity, designed to bring nanoscale into the familiar macroworld, is from a two-week workshop on nanotechnology conducted by Fisk University in Nashville, Tennessee that was sponsored by the National Center for Learning and Teaching in Nanoscale Science and Engineering (NCLT) and the National Science Foundation (NSF).

Cherry, Elvis H.; Chang, R. P.; Lu, Weijie

2008-04-01

74

The properties of B-Sb thin films prepared by molecular flow region PVD process  

NASA Astrophysics Data System (ADS)

The present paper is the first description on the electrical and thermoelectric properties of amorphous PVD B 12Sb 2 films prepared using the reaction of decaborane gas with evaporated antimony gas on Si (1900 Å) / SiO x (3700 Å) / Si (100) (625 ?m) substrate at the temperature 350°C. Ohmic metals contacts of the film were examined by making evaporated Al, followed by annealing at 200°C. The comparatively high mobility of ˜100 cm 2/V s and high thermoelectric figures-of-merit of ˜10 -4/K were confirmed.

Kumashiro, Y.; Nakamura, K.; Sato, K.; Ohtsuka, M.; Ohishi, Y.; Nakano, M.; Doi, Y.

2004-02-01

75

The preparation of B?Sb thin films by molecular flow region PVD process  

NASA Astrophysics Data System (ADS)

The present paper is the first description on the preparation of B-Sb films by molecular flow region PVD method using the reaction of decaborane gas with evaporated antimony gas on Si(1 0 0) substrate at the temperatures 200-400°C. The cracking of evaporated Sb 2 into Sb 1 produced the films with the composition of amorphous B 12Sb 2 determined by X-ray photoelectron spectroscopy and infrared spectra. Ohmic metals of the films were examined by making evaporated Ag followed by annealing at 200°C.

Kumashiro, Y.; Nakamura, K.; Doi, Y.; Hirata, K.; Yokoyama, T.; Sato, K.

2002-04-01

76

Structural characterisation of oxygen diffusion hardened alpha-tantalum PVD-coatings on titanium.  

PubMed

Titanium substrates were coated with tantalum layers of 5 ?m thickness using physical vapour deposition (PVD). The tantalum layers showed a (110)-preferred orientation. The coated samples were hardened by oxygen diffusion. Using X-ray diffraction the crystallographic structure of the tantalum coatings was characterised, comparing untreated and diffusion hardened specimen conditions. Oxygen depth profiles were determined by glow discharge spectrometry. The hardening effect of the heat treatment was examined by Vickers microhardness testing. The increase of surface hardness caused by oxygen diffusion was at least 50%. PMID:24907733

Hertl, C; Koll, L; Schmitz, T; Werner, E; Gbureck, U

2014-08-01

77

Harvesting nanoscale thermal radiation using pyroelectric materials  

E-print Network

combine nanoscale radiative heat transfer and pyroelectric energy conversion in a device harvestingcombines, for the ?rst time, nanoscale thermal radiation and pyroelectric energy conversion for harvesting

Fang, Jin; Frederich, Hugo; Pilon, Laurent

2010-01-01

78

Influence of EB-PVD TBC Microstructure on Thermal Barrier Coating System Performance Under Cyclic Conditions  

SciTech Connect

The lifetimes of electron beam physical vapor deposited (EB-PVD) thermal barrier coating systems (TBCs) with three different microstructures of the Y2O3-stabilized ZrO, YSZ) ceramic top layer were investigated in lh thermal cycles at 1100 and 1150°C in flowing oxygen. Single crystal alloys CMSX-4 and Rene N5 that had been coated with an EB-PVD NiCoCrAlY bond coat were chosen as substrate materials. At 1150°C all samples failed after 80-100, lh cycles, predominantly at the bond coat/alumina interface after cooling down from test temperature. The alumina scale remained adherent to the YSZ after spallation. Despite the different YSZ microstructures no clear tendency regarding differences in spallation behavior were observed at 1150°C. At 1100°C the minimum lifetime was 750 , lh cycles for CMSX-4, whereas the first Rene N5 specimen failed after 1750, lh cycles. The longest TBC lifetime on CMSX-4 substrates was 1250, lh cycles, whereas the respective Rene N5 specimens have not yet failed after 2300, lh cycles. The failure mode at 1100°C was identical to that at 115O?C, i.e. the TBC spalled off the surface exposing bare metal after cooling. Even though not all specimens have failed to date, the available results at 1100°C suggested that both, the substrate alloy chemistry and the YSZ microstructure significantly affect the spallation resistance of the TBC.

Leyens, C.; Pint, B.A.; Schulz, U.; Wright, I.G.

1999-04-12

79

Investigation of Ti and Cr based PVD coatings deposited onto HSS Co 5 twist drills  

NASA Astrophysics Data System (ADS)

This study investigates the properties and cutting performance of thin TiN, TiAlN, CrAlN and KTRN coatings applied by two PVD techniques. PVD techniques ARC and SARC (it denotes the arc method by STATON company, Slovakia - deposited with smaller microdrops) were used for the deposition of thin coatings onto twist drills prepared by powder metallurgy. Conventional types of coatings - monolayers TiN, TiAlN, CrAlN and advanced type of the coating - monolayer KTRN (denoted by producer - STATON company Slovakia) on the basis of Ti and Al deposited with smaller drops on the surface - were analyzed by standard techniques for surface status and quality assessment - coating thickness, chemical composition by EDX analysis, adhesion, hardness, roughness and tribological properties at room temperature. Durability testing of the twist drills was carried out according to the standard ISO 3685-1999. CrAlN and TiAlN monolayers achieved lower roughness when compared to monolayer TiN and advanced type of the monolayer KTRN. TiAlN and KTRN coatings which leads to the achievement of higher hardness and better coating quality. The microhardness values were ?35 GPa. The results showed two to four times lower flank wear VB of the evaluated drills with TiAlN and KTRN coatings in comparison with equivalent uncoated material of the drill. The deposited TiAlN and KTRN coatings contributed to the improvement of their durability.

Kottfer, D.; Ferdinandy, M.; Kaczmarek, L.; Ma?ková, I.; Be?o, J.

2013-10-01

80

Structure and properties of jet vapor deposited aluminum-aluminum oxide nanoscale laminates  

Microsoft Academic Search

Recently, the authors have fabricated aluminum-aluminum oxide (presumably Al[sub 2]O[sub 3]) nanoscale laminates using the novel Jet Vapor Deposition (JVD) process. The JVD process is of interest because it uses high speed (He) gas jets in low vacuum'' to inexpensively deposit multilayered thin films (laminates) at potentially very high rates (0.1 [approximately] 1 cm[sup 3]\\/min). A preliminary study of the

L. M. Hsiung; H. N. G. Wadley; J. Z. Zhang; B. L. Halpern; J. J. Schmitt; D. C. McIntyre

1993-01-01

81

Computing and fabricating multilayer models  

E-print Network

We present a method for automatically converting a digital 3D model into a multilayer model: a parallel stack of high-resolution 2D images embedded within a semi-transparent medium. Multilayer models can be produced quickly ...

Holroyd, Michael

82

Electroanalysis at the nanoscale.  

PubMed

This article reviews the state of the art of silicon chip-based nanoelectrochemical devices for sensing applications. We first describe analyte mass transport to nanoscale electrodes and emphasize understanding the importance of mass transport for the design of nanoelectrode arrays. We then describe bottom-up and top-down approaches to nanoelectrode fabrication and integration at silicon substrates. Finally, we explore recent examples of on-chip nanoelectrodes employed as sensors and diagnostics, finishing with a brief look at future applications. PMID:24818810

Dawson, Karen; O'Riordan, Alan

2014-01-01

83

Nanotribology and Nanoscale Friction  

SciTech Connect

Tribology is the science and technology of contacting solid surfaces in relative motion, including the study of lubricants, lubrication, friction, wear, and bearings. It is estimated that friction and wear cost the U.S. economy 6% of the gross national product (Persson, 2000). For example, 5% of the total energy generated in an automobile engine is lost to frictional resistance. The study of nanoscale friction has a technological impact in reducing energy loss in machines, in microelectromechanical systems (MEMS), and in the development of durable, low-friction surfaces and ultra-thin lubrication films.

Guo, Yi [Stevens Institute of Technology, Hoboken, New Jersey; Qu, Zhihua [University of Central Florida, Orlando; Braiman, Yehuda [ORNL; Zhang, Zhenyu [ORNL; Barhen, Jacob [ORNL

2008-01-01

84

Microfluidics and Nanoscale Research Profile  

E-print Network

Microfluidics and Nanoscale Science Research Profile Our research group is engaged in a broad range of activities in the general area of microfluidics and nanoscale science. At a primary level, our interest that when compared to macroscale tech- nology, microfluidic systems engender a number of distinct advantages

85

Multilayered Graphene in Microwaves  

NASA Astrophysics Data System (ADS)

We report on the experimental study of electromagnetic (EM) properties of multilayered graphene in Ka-band synthesized by catalytic chemical vapor deposition (CVD) process in between nanometrically thin Cu catalyst film and dielectric (SiO2) substrate. The quality of the produced multilayered graphene samples were monitored by Raman spectroscopy. The thickness of graphene films was controlled by atomic force microscopy (AFM) and was found to be a few nanometers (up to 5 nm). We discovered, that the fabricated graphene provided remarkably high EM shielding efficiency caused by absorption losses at the level of 35-43% of incident power. Being highly conductive at room temperature, multi-layer graphene emerges as a promising material for manufacturing ultrathin microwave coatings to be used in aerospace applications.

Kuzhir, P.; Volynets, N.; Maksimenko, S.; Kaplas, T.; Svirko, Yu.

2013-05-01

86

Ensuring the adhesion and cohesion strength of PVD (TiAl)N and TiN coatings  

NASA Astrophysics Data System (ADS)

The fracture of PVD coatings as a result of bulging and cohesion cracking is shown to be controlled by creating a discrete coating surface topography. For longitudinal compression, the discrete region size is calculated using the theory of stability of elastic systems; under tensile stresses, the coating region size is chosen on the basis of the calculated crack step.

Soroka, E. B.; Klimenko, S. A.; Kopeikina, M. Yu.

2011-04-01

87

A study of the erosion–corrosion of PVD CrN\\/NbN superlattice coatings in aqueous slurries  

Microsoft Academic Search

New generation PVD coatings include advanced “superlattice” structures in which the combination of tribological and corrosion properties may optimized. Such coatings of the CrN\\/NbN type offer the possibility of enhanced wear and corrosion resistance. However, there has been little work carried out to date to identify the mechanisms of wear of these coatings in environments where solid particles may impact

Y. Purandare; M. M. Stack; P. Hovsepian

2005-01-01

88

Resilience in multilayer networks  

Microsoft Academic Search

. The integration of different technologies such as ATM, SDH and WDMin future multi-layer transport networks requires a better coordination between theindividual network layers. Especially in the area of network survivability, it is feltthat much can be gained by a better coordination and integration of the healingactions taken by the different layers in the event of failures. We present aframework

Piet Demeester; Michael Gryseels; A. Autenrieth; C. Brianza; L. Castagna; G. Signorelli; R. Clemenfe; M. Ravera; A. Jajszczyk; D. Janukowicz; K. Van Doorselaere; Y. Harada

1999-01-01

89

Photovoltaics at the nanoscale  

NASA Astrophysics Data System (ADS)

Nanoscale thin film morphology has been identified as an important factor in organic solar cell device func- tionality and efficiency. To better understand the limiting factors, it is important to work at the length scale of these processes. A study of thin films of organic molecules with Kelvin probe force microscopy (KPFM) to observe charge distribution and non-contact atomic force microscopy (NC-AFM) to simultaneously obtain structural information is presented. This allows investigation of the structure-function relationships in molecu- lar photovoltaics at the nanometer scale. PTCDI (3,4,9,10-perylenetetracarboxylic diimide) and CuPc (copper phthalocyanine) are used as organic molecules and are precisely grown on alkali halide substrates.

Schumacher, Zeno; Topple, Jessica; Tekiel, Antoni; Grütter, Peter

2013-09-01

90

Nanogrinding of multi-layered thin film amorphous Si solar panels  

Microsoft Academic Search

Nanogrinding was performed on the cross-sections of amorphous Si thin film solar panels, which are nanoscale multi-layer structures consisting of hard and brittle materials. The deformed structures of the panel cross-sectional surfaces after grinding were investigated using electron and atomic force microscopy. The nanogrinding results were compared with those obtained from polishing and nanoscratching, demonstrating that the three processes had

Taro Sumitomo; Han Huang; Libo Zhou; Jun Shimizu

2011-01-01

91

Polarizing multilayer spectrometer for neutrons  

SciTech Connect

Polarizing neutron monochromators were prepared by sputtering thin-film multilayers with d-spacings from 40 to 85A on large float-glass substrates. Peak reflectivities as great as 90% and polarizing efficiencies of 98% were measured. Increased angular acceptances were obtained by fabricating multilayers with multiple d- spacings. A planned polarized beam spectrometer which incorporates the multilayers and which has a variable energy resolution independent of angular beam divergence is described.

Majkrzak, C.F.; Passell, L.; Saxena, A.M.

1981-01-01

92

Thermometry at the nanoscale.  

PubMed

Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field of research. This has been strongly stimulated by the numerous challenging requests arising from nanotechnology and biomedicine. This critical review offers a general overview of recent examples of luminescent and non-luminescent thermometers working at nanometric scale. Luminescent thermometers encompass organic dyes, QDs and Ln(3+)ions as thermal probes, as well as more complex thermometric systems formed by polymer and organic-inorganic hybrid matrices encapsulating these emitting centres. Non-luminescent thermometers comprise of scanning thermal microscopy, nanolithography thermometry, carbon nanotube thermometry and biomaterials thermometry. Emphasis has been put on ratiometric examples reporting spatial resolution lower than 1 micron, as, for instance, intracellular thermometers based on organic dyes, thermoresponsive polymers, mesoporous silica NPs, QDs, and Ln(3+)-based up-converting NPs and ?-diketonate complexes. Finally, we discuss the challenges and opportunities in the development for highly sensitive ratiometric thermometers operating at the physiological temperature range with submicron spatial resolution. PMID:22763389

Brites, Carlos D S; Lima, Patricia P; Silva, Nuno J O; Millán, Angel; Amaral, Vitor S; Palacio, Fernando; Carlos, Luís D

2012-08-21

93

Thermometry at the nanoscale  

NASA Astrophysics Data System (ADS)

Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field of research. This has been strongly stimulated by the numerous challenging requests arising from nanotechnology and biomedicine. This critical review offers a general overview of recent examples of luminescent and non-luminescent thermometers working at nanometric scale. Luminescent thermometers encompass organic dyes, QDs and Ln3+ions as thermal probes, as well as more complex thermometric systems formed by polymer and organic-inorganic hybrid matrices encapsulating these emitting centres. Non-luminescent thermometers comprise of scanning thermal microscopy, nanolithography thermometry, carbon nanotube thermometry and biomaterials thermometry. Emphasis has been put on ratiometric examples reporting spatial resolution lower than 1 micron, as, for instance, intracellular thermometers based on organic dyes, thermoresponsive polymers, mesoporous silica NPs, QDs, and Ln3+-based up-converting NPs and ?-diketonate complexes. Finally, we discuss the challenges and opportunities in the development for highly sensitive ratiometric thermometers operating at the physiological temperature range with submicron spatial resolution.

Brites, Carlos D. S.; Lima, Patricia P.; Silva, Nuno J. O.; Millán, Angel; Amaral, Vitor S.; Palacio, Fernando; Carlos, Luís D.

2012-07-01

94

PVD Silicon Carbide as a Thin Film Packaging Technology for Antennas on LCP Substrates for Harsh Environments  

NASA Technical Reports Server (NTRS)

This paper describes an effort to develop a thin film packaging technology for microfabricated planar antennas on polymeric substrates based on silicon carbide (SiC) films deposited by physical vapor deposition (PVD). The antennas are coplanar waveguide fed dual frequency folded slot antennas fabricated on liquid crystal polymer (LCP) substrates. The PVD SiC thin films were deposited directly onto the antennas by RF sputtering at room temperature at a chamber pressure of 30 mTorr and a power level of 300 W. The SiC film thickness is 450 nm. The return loss and radiation patterns were measured before and after the SiC-coated antennas were submerged into perchloric acid for 1 hour. No degradation in RF performance or physical integrity of the antenna was observed.

Scardelletti, Maximilian C.; Stanton, John W.; Ponchak, George E.; Jordan, Jennifer L.; Zorman, Christian A.

2010-01-01

95

Nanocrystalline filtered arc deposited (FAD) TiAlN PVD coatings for high-speed machining applications  

Microsoft Academic Search

The main advantage of the filtered arc deposition (FAD) technique is a significant grain refinement that leads to the formation of nano-crystalline (grain size approx. 60–80 nm) PVD coatings. This technique improves the wear resistance of FAD TiAlN coatings under high-speed machining conditions when cutting tool oxidation wear is dominant. A study of the surface structure characteristics of the FAD

G. S. Fox-Rabinovich; G. C. Weatherly; A. I. Dodonov; A. I. Kovalev; L. S. Shuster; S. C. Veldhuis; G. K. Dosbaeva; D. L. Wainstein; M. S. Migranov

2004-01-01

96

Laboratory characterisation of the wear behaviour of PVD-coated tool steels and correlation with cutting tool performance  

Microsoft Academic Search

Four different characterisation tests have been used to study the wear behaviour of a series of thin (1–4 ?m) PVD coatings of TiN, TiCN, TiAlN and CrN on identical M2 tool steel substrates. These include two novel tests involving micro-abrasion and erosion durability. The abrasion method provides values for the intrinsic wear behaviour of both the coating and the substrate

K. L. Rutherford; S. J. Bull; E. D. Doyle; I. M. Hutchings

1996-01-01

97

Development of CVD-W coatings on CuCrZr and graphite substrates with a PVD intermediate layer  

NASA Astrophysics Data System (ADS)

In order to apply tungsten (W) coatings by chemical vapor deposition (CVD) for repairing or updating the plasma facing components (PFCs) of the first wall and divertor in existing or future tokomaks, where CuCrZr or graphite is the substrate material, an intermediate layer by physical vapor deposition (PVD) has been used to accommodate the interface stress due to the mismatch of thermal expansion or act as a diffusion barrier between the CVD-W coating and the substrate. The prepared CuCrZr/PVD-Cu/CVD-W sample with active cooling has passed thermal fatigue tests by electron beam with an absorbed power of 2.2 MW/m2, 50 s on/50 s off, for 100 cycles. Another graphite/PVD-Si/CVD-W sample without active cooling underwent thermal fatigue testing with an absorbed power density of 4.62 MW/m2, 5 s on/25 s off, for 200 cycles, and no catastrophic failure was found.

Song, Jiupeng; Lian, Youyun; Lv, Yanwei; Liu, Junyong; Yu, Yang; Liu, Xiang; Yan, Binyou; Chen, Zhigang; Zhuang, Zhigang; Zhao, Ximeng; Qi, Yang

2014-12-01

98

Cloning and nucleotide sequence of the pvdA gene encoding the pyoverdin biosynthetic enzyme L-ornithine N5-oxygenase in Pseudomonas aeruginosa.  

PubMed Central

The enzyme L-ornithine N5-oxygenase catalyzes the hydroxylation of L-ornithine (L-Orn), which represents an early step in the biosynthesis of the peptidic moiety of the fluorescent siderophore pyoverdin in Pseudomonas aeruginosa. A gene bank of DNA from P. aeruginosa PAO1 (ATCC 15692) was constructed in the broad-host-range cosmid pLAFR3 and mobilized into the L-Orn N5-oxygenase-defective (pvdA) P. aeruginosa mutant PALS124. Screening for fluorescent transconjugants made it possible to identify the trans-complementing cosmid pPV4, which was able to restore pyoverdin synthesis and L-Orn N5-oxygenase activity in the pvdA mutant PALS124. The 17-kb PAO1 DNA insert of pPV4 contained at least two genetic determinants involved in pyoverdin synthesis, i.e., pvdA and pvdC4, as shown by complementation analysis of a set of mutants blocked in different steps of the pyoverdin biosynthetic pathway. Deletion analysis, subcloning, and transposon mutagenesis enabled us to locate the pvdA gene in a minimum DNA fragment of 1.7 kb flanked by two SphI restriction sites. Complementation of the pvdA mutation was under stringent iron control; both pyoverdin synthesis and L-Orn N5-oxygenase activity were undetectable in cells of the trans-complemented mutant which had been grown in the presence of 100 microM FeCl3. The entire nucleotide sequence of the pvdA gene, from which the primary structure of the encoded polypeptide was deduced, was determined. The pvdA structural gene is 1,278 bp; the cloned DNA fragment contains at the 5' end of the gene a putative ribosome-binding site but apparently lacks known promoterlike sequences. The P. aeruginosa L-Orn N5-oxygenase gene codes for a 426-amino-acid peptide with a predicted molecular mass of 47.7 kDa and an isoelectric point of 8.1. The enzyme shows approximately 50% homology with functional analogs, i.e., L-lysine N6-hydroxylase of aerobactin-producing Escherichia coli and L-Orn N5-oxygenase of ferrichrome-producing Ustilago maydis. The pvdA gene was expressed in P. aeruginosa under the control of the T7 promoter. Induction of the T7 RNA polymerase system resulted in parallel increases of the L-Orn N5-oxygenase activity and of the amount of a 47.7-kDa polypeptide. We also constructed a site-specific pvdA mutant by insertion of a tetracycline-resistance cassette in the chromosomal pvdA gene of P. aeruginosa PAO1. Similarly to strain PALS124, the pvdA mutant obtained by gene disruption also disclosed no pyoverdin synthesis, lacked L-Orn N5-oxygenase activity, was complemented by the cloned pvdA gene, and produced pyoverdin at wild-type levels when fed with the biosynthetic precursor L-N5-OH-Orn. Southern blot analysis indicated that genes homologous to pvdA could be located within a 1.7-kb DNA fragment from SphI-digested genomic DNA of different hydroxamate-producing Pseudomonas spp. Our results suggest that omega-amino acid oxygenases have been conserved over a wide evolutionary range and probably evolved from a common ancestor. Images PMID:8106324

Visca, P; Ciervo, A; Orsi, N

1994-01-01

99

Process for manufacturing multilayer capacitors  

DOEpatents

The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. 4 figs.

Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

1996-01-02

100

Process for manufacturing multilayer capacitors  

DOEpatents

The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

Lauf, Robert J. (Oak Ridge, TN); Holcombe, Cressie E. (Knoxville, TN); Dykes, Norman L. (Oak Ridge, TN)

1996-01-01

101

Unconventional Patterning at the Nanoscale  

NSDL National Science Digital Library

A team of students and professors at Northwestern University created this course as a how-to guide to many basic nanoscale patterning procedures. It is a video lab manual that will give students training in soft lithography, for example, molding. Students will also be able to synthesize, characterize, and create nanoscale devices using common, cheap materials, and some typical chemicals. Along with each procedural video, there are also tutorials to explain the meaning and purpose of each experiment. This is a valuable website for institutions that want to introduce nanopatterning to their students, but have limited resources to do so. Computers must have Quick Time installed on them before viewing these videos.

Babayan, Y.; Odom, Teri W.; Viswanathan, M.

2012-04-12

102

Amazing Creatures with Nanoscale Features  

NSDL National Science Digital Library

This animation is an introduction to microscopy, scale, and applications of nanoscale properties. It introduces some of the tools that are used by scientists to visualize samples that are smaller than what we can see with our eyes. This includes the optical microscope, scanning electron microscope, and the atomic force microscope. In this animation, you will take a closer look at a butterfly wing at different magnifications and see features at the nanoscale that give the butterfly unique properties. Then, you will learn how scientists and engineers are able to mimic these structures through engineering techniques.

2011-10-26

103

Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 ?m obtain leakage rates of less than 3 × 10-4 hPa dm3 s-1 cm-2 (?p: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm-2 at 850 °C and underline the high potential of MSC cells.

Haydn, Markus; Ortner, Kai; Franco, Thomas; Uhlenbruck, Sven; Menzler, Norbert H.; Stöver, Detlev; Bräuer, Günter; Venskutonis, Andreas; Sigl, Lorenz S.; Buchkremer, Hans-Peter; Vaßen, Robert

2014-06-01

104

Evaluation of Osseous Integration of PVD-Silver-Coated Hip Prostheses in a Canine Model  

PubMed Central

Infection associated with biomaterials used for orthopedic prostheses remains a serious complication in orthopedics, especially tumor surgery. Silver-coating of orthopedic (mega)prostheses proved its efficiency in reducing infections but has been limited to surface areas exposed to soft tissues due to concerns of silver inhibiting osseous integration of cementless stems. To close this gap in the bactericidal capacity of silver-coated orthopedic prostheses extension of the silver-coating on surface areas intended for osseous integration seems to be inevitable. Our study reports about a PVD- (physical-vapor-deposition-) silver-coated cementless stem in a canine model for the first time and showed osseous integration of a silver-coated titanium surface in vivo. Radiological, histological, and biomechanical analysis revealed a stable osseous integration of four of nine stems implanted. Silver trace elemental concentrations in serum did not exceed 1.82 parts per billion (ppb) and can be considered as nontoxic. Changes in liver and kidney functions associated with the silver-coating could be excluded by blood chemistry analysis. This was in accordance with very limited metal displacement from coated surfaces observed by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) 12 months after implantation. In conclusion our results represent a step towards complete bactericidal silver-coating of orthopedic prostheses.

Hauschild, Gregor; Hardes, Jendrik; Gosheger, Georg; Blaske, Franziska; Wehe, Christoph; Karst, Uwe; Höll, Steffen

2015-01-01

105

Effect of Hf Additions to Pt Aluminide Bond Coats on EB-PVD TBC Life  

NASA Technical Reports Server (NTRS)

Small Hf additions were incorporated into a Pt aluminide coating during chemical vapor deposition (CVD) on single crystal RENE N5 substrates. Standard yttria-stabilized zirconia top coats were subsequently deposited onto the coated substrates by electron beam-physical vapor deposition (EB-PVD). The coated substrates underwent accelerated thermal cycle testing in a furnace at a temperature in excess of 1121 C (2050 F) (45 minute hot exposure, 15 minute cool to approximately 121 C (250 F)) until the thermal barrier coating (TBC) failed by spallation. Incorporating Hf in the bond coat increased the TBC life by slightly more than three times that of a baseline coating without added Hf. Scanning electron microscopy of the spalled surfaces indicated that the presence of the Hf increased the adherence of the thermally grown alumina to the Pt aluminide bond coat. The presence of oxide pegs growing into the coating from the thermally grown alumina may also partially account for the improved TBC life by creating a near-surface layer with a graded coefficient of thermal expansion.

Nesbitt, James; Nagaraj, Ben; Williams, Jeffrey

2000-01-01

106

Control of particle flux and energy on substrate in an inverted cylindrical magnetron for plasma PVD  

NASA Astrophysics Data System (ADS)

Inverted cylindrical magnetrons (ICMs) are often used in dc, pulsed dc or mid-frequency ac mode for coating complex objects with thin films deposited by plasma PVD. Since in such a configuration the substrate is inherently surrounded by the target and hence by the plasma, the energy flux of the impinging particles represents the main contribution to the substrate heating. This can readily constitute a limiting factor in the deposition process, especially when it is not possible to cool and bias the substrate. This work concerns a dc-driven ICM configuration subjected to several constraints: not only is the substrate surface area small by comparison to the cathode surface area, but its imposed potential is the ground one, thus itself constituting the anode surface of the considered setup. Several important substrate heating factors are highlighted and, in order to reduce the most prominent of them, a means to raise the plasma potential is proposed. This is achieved by positively polarizing two additional electrodes with respect to the ground. This additional surface generates a redistribution of the current and consequently regulates the electron flux on the substrate. The results are shown as a function of bias applied on the auxiliary electrodes and discussed in terms of the impact on the substrate heating.

Todoran, A.; Mantel, M.; Bés, A.; Vachey, C.; Lacoste, A.

2014-12-01

107

Nanoscale eletromechanical behavior  

NASA Astrophysics Data System (ADS)

In this dissertation, we try to address some of the questions which arise while understanding the electromechanical behavior at the nanoscale. (1) Metals exhibit a size-dependent hardening when subjected to indentation. Mechanisms for this phenomenon have been intensely researched in recent times. Does such a size-effect also exist in the electromechanical behavior of ferroelectrics? If yes, what are the operative mechanisms? Experiments on BaTiO3 indeed suggest an elastic electromechanical size-effect. We argue, through theoretical calculations and differential experiments on another non-ferroelectric piezoelectric (Quartz), that the phenomenon of flexoelectricity (as opposed to dislocation activity) is most likely responsible for our observations. (2) Using a combination of a theoretical framework and atomistic calculations, we highlight the concept of surface piezoelectricity that can be used to interpret the piezoelectricity of nanostructures. Focusing on three specific material systems (ZnO, SrTiO3 and BaTiO3), we discuss the renormalization of apparent piezoelectric behavior at small scales. In a rather interesting interplay of symmetry and surface effects, we show that nanostructures of certain non-piezoelectric materials may also exhibit piezoelectric behavior. For the case of ZnO, using a comparison with first principles calculations, we also comment on the fidelity of the widely-used core-shell interatomic potentials to capture non-bulk electro-mechanical response. (3) Building entire devices with multiple components on single nanowires will lead to the ultimate miniaturization promised by nanotechnology. The capacitance measured from a single coaxial nanowire capacitor Cu-Cu2O-C device corresponds to ˜294microF/cm2, which considerably exceeds previously reported values for metal-insulator-metal micro-capacitors and is nearly fifty times larger than what is predicted by classical electrostatics. Our quantum mechanical calculations indicate that this unusually high capacitance value is attributed to negative quantum capacitance of the dielectric-metal interface. Also, we argue through first principle calculations on Graphene-Boron Nitrate-Graphene capacitors that quantum capacitance plays a key role in decreasing the total effective capacitance.

Gharbi, Mohamed

108

Ultrahard Multilayer Coatings  

SciTech Connect

We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600°C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc.

Chrzan, D.C.; Dugger, M.; Follstaedt, D.M.; Friedman, Lawrence H.; Friedmann, T.A.; Knapp, J.A.; McCarty, K.F.; Medlin, D.L.; Mirkarimi, P.B.; Missert, N.; Newcomer, P.P.; Sullivan, J.P.; Tallant, D.R.

1999-05-01

109

Screening in multilayer graphene  

NASA Astrophysics Data System (ADS)

In this paper, we study the static polarization in ABC-stacked multilayer graphene. Since the density of states diverges for these systems if the number of layers exceeds three, screening effects are expected to be important. In the random phase approximation, screening can be included through the polarization. We derive an analytical integral expression for the polarization in both the full-band model and an effective two-band model. Numerical evaluation of these integrals is very time consuming in the full-band model. Hence, for ABC-stacked trilayer graphene, we use the two-band model to calculate the low momentum part of the polarization. The results for the two-band model are universal, i.e., independent of doping. The high momentum part is linear and is determined by calculating two points, such that we can determine the slope. For ABC stacked trilayer graphene, the slope is given by three times the monolayer value. We compare our results to previous ones in the literature and discuss the similarities and discrepancies. Our results can be used to include screening in ABC-stacked multilayer systems in a way that all the characteristics of the polarization function are included. The numerical results for the polarization of trilayer graphene are used to sketch the screened potential.

van Gelderen, Ralph; Olsen, Richard; Smith, C. Morais

2013-09-01

110

Nanoscale Twins Formed by Plastic  

E-print Network

Nanoscale Twins Formed by Plastic Accommodations in Nano Bainite Hung-Wei Yen Hsiao-Tzu Chang Jer. #12;Coherent TBs Strengthening Metals · Nano Twins with coherent grain boundary has been reported). 0 20 40 60 80 100 #12;Twinning in Steels · Twinning in steels can be achieved by several different

Cambridge, University of

111

Nanoscale wicking methods and devices  

NASA Technical Reports Server (NTRS)

A fluid transport method and fluid transport device are disclosed. Nanoscale fibers disposed in a patterned configuration allow transport of a fluid in absence of an external power source. The device may include two or more fluid transport components having different fluid transport efficiencies. The components may be separated by additional fluid transport components, to control fluid flow.

Zhou, Jijie (Inventor); Bronikowski, Michael (Inventor); Noca, Flavio (Inventor); Sansom, Elijah B. (Inventor)

2011-01-01

112

Sensing at the nanoscale  

NASA Astrophysics Data System (ADS)

The merits of nanostructures in sensing may seem obvious, yet playing these attributes to their maximum advantage can be a work of genius. As fast as sensing technology is improving, expectations are growing, with demands for cheaper devices with higher sensitivities and an ever increasing range of functionalities and compatibilities. At the same time tough scientific challenges like low power operation, noise and low selectivity are keeping researchers busy. This special issue on sensing at the nanoscale with guest editor Christofer Hierold from ETH Zurich features some of the latest developments in sensing research pushing at the limits of current capabilities. Cheap and easy fabrication is a top priority. Among the most popular nanomaterials in sensing are ZnO nanowires and in this issue Dario Zappa and colleagues at Brescia University in Italy simplify an already cheap and efficient synthesis method, demonstrating ZnO nanowire fabrication directly onto silicon substrates [1]. Meanwhile Nicolae Barson and colleagues in Germany point out the advantages of flame spray pyrolysis fabrication in a topical review [2] and, maximizing on existing resources, researchers in Denmark and Taiwan report cantilever sensing using a US20 commercial DVD-ROM optical pickup unit as the readout source [3]. The sensor is designed to detect physiological concentrations of soluble urokinase plasminogen activator receptor, a protein associated with inflammation due to HIV, cancer and other infectious diseases. With their extreme properties carbon nanostructures feature prominently in the issue, including the demonstration of a versatile and flexible carbon nanotube strain sensor [4] and a graphene charge sensor with sensitivities of the order of 1.3 × 10-3 e Hz-1/2 [5]. The issue of patterning for sensing devices is also tackled by researchers in the US who demonstrate a novel approach for multicomponent pattering metal/metal oxide nanoparticles on graphene [6]. Changes in electrical properties are an important indicator for sensing. In search of a better understanding of these systems Zhang et al from Southern Illinois University inspect the role of Joule heating, exothermal reactions and heat dissipation in gas sensing using nanowires [7]. The mechanisms behind electrical chemical sensors are also further scrutinized in a kinetics study by Joan Ramon Morante from the University of Barcelona in Spain. 'In spite of the growing commercial success many basic issues remain still open and under discussion limiting the broad use of this technology,' he explains. He discusses surface chemical reaction kinetics and the experimental results for different representative gas molecules to gain an insight into the chemical to electrical transduction mechanisms taking place [8]. Perhaps one of the most persistent targets in sensing research is increasing the sensitivity. Gauging environmental health issues around the commercial use of nanomaterials places high demands on low-level detection and spurred a collaboration of researchers in the UK, Croatia and Canada to look into the use of particle-impact voltammetry for detecting nanoparticles in environmental media [9]. At the University of Illinois Urbana-Champaign in the US, researchers have applied wave transform analysis techniques to the oscillations of an atomic force microscopy cantilever and tailored a time-frequency-domain filter to identify the region of highest vibrational energy [10]. The approach allows them to improve the signal to noise ratio by a factor 32 on current high-performance devices. In addition, researchers in Korea report how doping NiO nanofibres can improve the sensitivity to a number of gases, including ethanol, where the response was enhanced by as much as a factor of 217.86 [11]. Biomedicine is one of the largest industries for the application of nanotechnology in sensing. Demonstrating the state of the art, researchers in China use silicon wafers decorated with gold nanoparticles for label-free detection of DNA at concentrations as low as 1-10 fM, a sensitivity comparable t

Demming, Anna; Hierold, Christofer

2013-11-01

113

Three-Dimensional, Flexible Nanoscale Field-Effect Transistors as Localized Bioprobes  

NASA Astrophysics Data System (ADS)

Nanoelectronic devices offer substantial potential for interrogating biological systems, although nearly all work has focused on planar device designs. We have overcome this limitation through synthetic integration of a nanoscale field-effect transistor (nanoFET) device at the tip of an acute-angle kinked silicon nanowire, where nanoscale connections are made by the arms of the kinked nanostructure, and remote multilayer interconnects allow three-dimensional (3D) probe presentation. The acute-angle probe geometry was designed and synthesized by controlling cis versus trans crystal conformations between adjacent kinks, and the nanoFET was localized through modulation doping. 3D nanoFET probes exhibited conductance and sensitivity in aqueous solution, independent of large mechanical deflections, and demonstrated high pH sensitivity. Additionally, 3D nanoprobes modified with phospholipid bilayers can enter single cells to allow robust recording of intracellular potentials.

Tian, Bozhi; Cohen-Karni, Tzahi; Qing, Quan; Duan, Xiaojie; Xie, Ping; Lieber, Charles M.

2010-08-01

114

Direct nano-scale patterning of Ag films using hard X-ray induced oxidation.  

PubMed

The morphological change of silver nano-particles (AgNPs) exposed to an intense synchrotron X-ray beam was investigated for the purpose of direct nano-scale patterning of metal thin films. AgNPs irradiated by hard X-rays in oxygen ambient were oxidized and migrated out of the illuminated region. The observed X-ray induced oxidation was utilized to fabricate nano-scale metal line patterns using sectioned WSi2/Si multilayers as masks. Lines with a width as small as 21?nm were successfully fabricated on Ag films on silicon nitride. Au/Ag nano-lines were also fabricated using the proposed method. PMID:25537602

Kim, Jae Myung; Lee, Su Yong; Kang, Hyon Chol; Noh, Do Young

2015-01-01

115

Multilayer optical dielectric coating  

DOEpatents

A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

Emmett, John L. (Pleasanton, CA)

1990-01-01

116

Multilayered folding with voids  

E-print Network

In the deformation of layered materials such as geological strata, or stacks of paper, mechanical properties compete with the geometry of layering. Smooth, rounded corners lead to voids between the layers, while close packing of the layers results in geometrically-induced curvature singularities. When voids are penalized by external pressure, the system is forced to trade off these competing effects, leading to sometimes striking periodic patterns. In this paper we construct a simple model of geometrically nonlinear multi-layered structures under axial loading and pressure confinement, with non-interpenetration conditions separating the layers. Energy minimizers are characterized as solutions of a set of fourth-order nonlinear differential equations with contact-force Lagrange multipliers, or equivalently of a fourth-order free-boundary problem. We numerically investigate the solutions of this free boundary problem, and compare them with the periodic solutions observed experimentally.

Timothy Dodwell; Giles Hunt; Mark Peletier; Chris Budd

2011-05-24

117

Ultra-thin multilayer capacitors  

Microsoft Academic Search

The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric

Timothy Jerome Renk; Todd C. Monson

2009-01-01

118

Multilayer thermal barrier coating systems  

DOEpatents

The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

2000-01-01

119

Optical antennas as nanoscale resonators  

E-print Network

Recent progress in nanotechnology has enabled us to fabricate subwavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interaction, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

Mario Agio

2011-11-05

120

Nanoscale plasticity in silica glass  

SciTech Connect

Mechanisms of nano-scale plasticity and damage initiation in silica glass is examined using molecular dynamics simulation. Computer experiments are carried out by indenting a sharp diamond-like tool, containing 4496 atoms, into a silica slab consisting of 12288 atoms. Both elastic and plastic deformation of silica is observed during nanoindentation simulation; this transition occurs at an indentation of 1.25 nm, and the calculated hardness (15GPa for 1.5 nm indentation) agrees with experiment.

Glosli, J.N.; Boercker, D.B.; Tesar, A.; Belak, J.

1993-10-01

121

Spinning light on the nanoscale.  

PubMed

Light beams with orbital angular momentum have significant potential to transform many areas of modern photonics from imaging to classical and quantum communication systems. We design and experimentally demonstrate an ultracompact array of nanowaveguides with a circular graded distribution of channel diameters that coverts a conventional laser beam into a vortex with an orbital angular momentum. The proposed nanoscale beam converter is likely to enable a new generation of on-chip or all-fiber structured light applications. PMID:24697576

Sun, Jingbo; Wang, Xi; Xu, Tianboyu; Kudyshev, Zhaxylyk A; Cartwright, Alexander N; Litchinitser, Natalia M

2014-05-14

122

Nanoscale Science and Engineering Center  

NSDL National Science Digital Library

With support from the National Science Foundation, the Nanoscale Science and Engineering Center (NSEC) brings together researchers from Harvard University, the Massachusetts Institute of Technology, the University of California, Santa Barbara and the Museum of Science in Boston with participation by Delft University of Technology (Netherlands), the University of Basel (Switzerland), the University of Tokyo (Japan), and Brookhaven, Oak Ridge and Sandia National Laboratories "to construct novel electronic and magnetic devices with nanoscale sizes and understand their behavior, including quantum phenomena." The Center's main activities include research, education, and public outreach. The website lists the group's overlapping interdisciplinary research areas as Synthesis and Growth of Nanoscale Structures; Imaging Electrons inside Nanostructures; and Spins and Charges in Coherent Electronics. The links section provides information on NCES nanotechnology educational activities as well as other online resources and information on upcoming conferences in nanotechnology. The Highlights section provides just an overview of recently published research, but some of the websites for individual participants include articles and conference papers. The Annual Report also reviews recent activities and research from NSEC.

123

Nanoscale Directional Motion towards Regions of Stiffness.  

PubMed

How to induce nanoscale directional motion via some intrinsic mechanisms pertaining to a nanosystem remains a challenge in nanotechnology. Here we show via molecular dynamics simulations that there exists a fundamental driving force for a nanoscale object to move from a region of lower stiffness toward one of higher stiffness on a substrate. Such nanoscale directional motion is induced by the difference in effective van der Waals potential energy due to the variation in stiffness of the substrate; i.e., all other conditions being equal, a nanoscale object on a stiffer substrate has lower van der Waals potential energy. This fundamental law of nanoscale directional motion could lead to promising routes for nanoscale actuation and energy conversion. PMID:25615480

Chang, Tienchong; Zhang, Hongwei; Guo, Zhengrong; Guo, Xingming; Gao, Huajian

2015-01-01

124

Junior Research Seminar: Nanoscale Patterning and Systems  

NSDL National Science Digital Library

Teri W. Odom, professor at Northwestern University, offers this course on Nanoscale Patterning and Systems. The research conducted through the course enables students to design and perform nanoscale patterning experiments with scanning probe lithography and bench-top fabrication techniques. The basic goals of the course are to help students understand current problems in nanoscale science and technology, perform bench-top nanoscale experiments, and use scanning probe techniques for patterning nanoscale features. To that end, this website offers a detailed syllabus explaining major concepts and breaking down the overall explanation of nanoscale patterning and systems, which students could use for better comprehension of nanotechnological concepts and instructors could use to help augment their own class materials.

Odom, Teri W.

2012-04-12

125

Nanoscale Directional Motion towards Regions of Stiffness  

NASA Astrophysics Data System (ADS)

How to induce nanoscale directional motion via some intrinsic mechanisms pertaining to a nanosystem remains a challenge in nanotechnology. Here we show via molecular dynamics simulations that there exists a fundamental driving force for a nanoscale object to move from a region of lower stiffness toward one of higher stiffness on a substrate. Such nanoscale directional motion is induced by the difference in effective van der Waals potential energy due to the variation in stiffness of the substrate; i.e., all other conditions being equal, a nanoscale object on a stiffer substrate has lower van der Waals potential energy. This fundamental law of nanoscale directional motion could lead to promising routes for nanoscale actuation and energy conversion.

Chang, Tienchong; Zhang, Hongwei; Guo, Zhengrong; Guo, Xingming; Gao, Huajian

2015-01-01

126

Analysis of the photo voltage decay /PVD/ method for measuring minority carrier lifetimes in P-N junction solar cells  

NASA Technical Reports Server (NTRS)

The photo voltage decay (PVD) method for the measurement of minority carrier lifetimes in P-N junction solar cells with cell thickness comparable to or even less than the minority carrier diffusion length is examined. The method involves the generation of free carriers in the quasi-neutral bulk material by flashes of light and the monitoring of the subsequent decay of the induced open-circuit voltages as the carriers recombine, which is dependent on minority carrier recombination lifetime. It is shown that the voltage versus time curve for an ordinary solar cell (N(+)-P junction) is proportional to the inverse minority carrier lifetime plus a factor expressing the ratio of diffusion length to cell thickness. In the case of an ideal back-surface-field cell (N(+)-P-P(+) junction) however, the slope is directly proportional to the inverse minority carrier lifetime. It is noted that since most BSF cells are not ideal, possessing a sizable back surface recombination velocity, the PVD measurements must be treated with caution and supplemented with other nonstationary methods.

Von Roos, O.

1981-01-01

127

Design of radiation resistant metallic multilayers for advanced nuclear systems  

NASA Astrophysics Data System (ADS)

Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation between reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.

Zhernenkov, Mikhail; Gill, Simerjeet; Stanic, Vesna; DiMasi, Elaine; Kisslinger, Kim; Baldwin, J. Kevin; Misra, Amit; Demkowicz, M. J.; Ecker, Lynne

2014-06-01

128

Design of radiation resistant metallic multilayers for advanced nuclear systems  

SciTech Connect

Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation between reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.

Zhernenkov, Mikhail, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Gill, Simerjeet, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Stanic, Vesna; DiMasi, Elaine; Kisslinger, Kim; Ecker, Lynne [Brookhaven National Laboratory, Upton, New York 11973 (United States); Baldwin, J. Kevin; Misra, Amit [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Demkowicz, M. J. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2014-06-16

129

Radiation rate enhancement in multilayered photonic and plasmonic nanopillars  

NASA Astrophysics Data System (ADS)

We have systematically studied arrays of multilayered nanopillars composed of both metal and dielectic materials and shown that they can be used to enhance the radiative properties of active materials through modification of the local density of states (LDOS). Using an extension of the multipolar expansion method in two dimensions, we are able to calculate modifications in the radiation rate of emitters and power radiated to the far field. We show multi-resonant confinement of light to sub-wavelength gap regions inside nanopillars composed of alternating layers of metal and dielectric materials, forming a circular metal-insulator-metal (MIM) device. Sub-wavelength light confinement of 1.55?m radiation is also demonstrated in purely dielectric nanopillars with reduced optical losses using alternating layers of high and low refractive index materials. In both cases, we find that the LDOS can be strongly increased, modifying the radiative rate and the internal quantum efficiency of emitters. Using top-down electron beam lithography, reactive ion etching and sputtering deposition we have created for the first time high-aspect ratio, light emitting, multilayered nanopillar structures consisting of alternating Si and Er:SiNx layers. Using dark-field scattering and photoluminescence decay spectroscopy we have experimentally characterized the fabricated nanostructures and demonstrated ability to control their radiation properties. These results are important to enable novel Si-based optical cavities and light emitting structures with nanoscale light confinement for optical communications and sensing.

Lawrence, Nate; Dal Negro, Luca

2013-03-01

130

Spatial dispersion of multilayer fishnet metamaterials  

E-print Network

Spatial dispersion of multilayer fishnet metamaterials Sergey S. Kruk, David A. Powell, Alexander the anisotropic properties of multilayer fishnet optical metamaterials and describe topological transitions fishnet metamaterials may have negative components not only in the effective permittivity tensor but also

131

Sectioning of multilayers to make a multilayer Laue lens  

SciTech Connect

We report a process to fabricate multilayer Laue lenses (MLL's) by sectioning and thinning multilayer films. This method can produce a linear zone plate structure with a very large ratio of zone depth to width (e.g., >1000), orders of magnitude larger than can be attained with photolithography. Consequently, MLL's are advantageous for efficient nanofocusing of hard x rays. MLL structures prepared by the technique reported here have been tested at an x-ray energy of 19.5 keV, and a diffraction-limited performance was observed. The present article reports the fabrication techniques that were used to make the MLL's.

Kang, Hyon Chol; Stephenson, G. Brian; Liu Chian; Conley, Ray; Khachatryan, Ruben; Wieczorek, Michael; Macrander, Albert T.; Yan Hanfei; Maser, Joerg; Hiller, Jon; Koritala, Rachel [Center for Nanoscale Materials and Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials and X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-04-15

132

Multi-layer micro/nanofluid devices with bio-nanovalves  

DOEpatents

A user-friendly multi-layer micro/nanofluidic flow device and micro/nano fabrication process are provided for numerous uses. The multi-layer micro/nanofluidic flow device can comprise: a substrate, such as indium tin oxide coated glass (ITO glass); a conductive layer of ferroelectric material, preferably comprising a PZT layer of lead zirconate titanate (PZT) positioned on the substrate; electrodes connected to the conductive layer; a nanofluidics layer positioned on the conductive layer and defining nanochannels; a microfluidics layer positioned upon the nanofluidics layer and defining microchannels; and biomolecular nanovalves providing bio-nanovalves which are moveable from a closed position to an open position to control fluid flow at a nanoscale.

Li, Hao; Ocola, Leonidas E.; Auciello, Orlando H.; Firestone, Millicent A.

2013-01-01

133

Structural and chemical investigations of CBD-and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells  

E-print Network

Structural and chemical investigations of CBD- and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells D. Abou-Rasa,b,*, G. Kostorza , A. Romeob,1 , D. Rudmannb , A Available online 8 December 2004 Abstract It is known that high-efficiency thin film solar cells based on Cu

Romeo, Alessandro

134

Reducing virulence of the human pathogen Burkholderia by altering the substrate specificity of the quorum-quenching acylase PvdQ  

PubMed Central

The use of enzymes to interfere with quorum sensing represents an attractive strategy to fight bacterial infections. We used PvdQ, an effective quorum-quenching enzyme from Pseudomonas aeruginosa, as a template to generate an acylase able to effectively hydrolyze C8-HSL, the major communication molecule produced by the Burkholderia species. We discovered that the combination of two single mutations leading to variant PvdQL?146W,F?24Y conferred high activity toward C8-HSL. Exogenous addition of PvdQL?146W,F?24Y dramatically decreased the amount of C8-HSL present in Burkholderia cenocepacia cultures and inhibited a quorum sensing-associated phenotype. The efficacy of this PvdQ variant to combat infections in vivo was further confirmed by its ability to rescue Galleria mellonella larvae upon infection, demonstrating its potential as an effective agent toward Burkholderia infections. Kinetic analysis of the enzymatic activities toward 3-oxo-C12-L-HSL and C8-L-HSL corroborated a substrate switch. This work demonstrates the effectiveness of quorum-quenching acylases as potential novel antimicrobial drugs. In addition, we demonstrate that their substrate range can be easily switched, thereby paving the way to selectively target only specific bacterial species inside a complex microbial community. PMID:24474783

Koch, Gudrun; Nadal-Jimenez, Pol; Reis, Carlos R.; Muntendam, Remco; Bokhove, Marcel; Melillo, Elena; Dijkstra, Bauke W.; Cool, Robbert H.; Quax, Wim J.

2014-01-01

135

Unfolding single- and multilayers  

NASA Astrophysics Data System (ADS)

When planar structures (e.g. sedimentary layers, veins, dykes, cleavages, etc.) are subjected to deformation, they have about equal chances to be shortened or stretched. The most common shortening and stretching structures are folds and boudinage, respectively. However, boudinage requires additional deformation mechanisms apart from viscous flow, like formation of fractures or strain localization. When folded layers are subjected to extension, they could potentially unfold back to straight layers. Although probably not uncommon, this would be difficult to recognize. Open questions are whether folded layers can unfold, what determines their mechanical behaviour and how we can recognize them in the field. In order to approach these questions, we present a series of numerical experiments that simulate stretching of previously folded single- and multi-layers in simple shear, using the two dimensional numerical modelling platform ELLE, including the finite element module BASIL that calculates viscous deformation. We investigate the parameters that affect a fold train once it rotates into the extensional field. The results show that the unfolding process strongly depends on the viscosity contrast between the layer and matrix (Llorens et al., 2013). Layers do not completely unfold when they experience softening before or during the stretching process or when other neighbouring competent layers prevent them from unfolding. The foliation refraction patterns are the main indicators of unfolded folds. Additionally, intrafolial folds and cusp-like folds adjacent to straight layers, as well as variations in fold amplitudes and limb lengths of irregular folds can also be used as indicators of stretching of a layer after shortening and folding. References: Llorens, M-.G., Bons, P.D., Griera, A. and Gomez-Rivas, E. 2013. When do folds unfold during progressive shear?. Geology, 41, 563-566.

Llorens, Maria-Gema; Bons, Paul D.; Griera, Albert; Gomez-Rivas, Enrique

2014-05-01

136

Integration of silver nanoparticle-impregnated polyelectrolyte multilayers into murine-splinted cutaneous wound beds.  

PubMed

Silver is a commonly used topical antimicrobial. However, technologies to immobilize silver at the wound surface are lacking, while currently available silver-containing wound dressings release excess silver that can be cytotoxic and impair wound healing. We have shown that precise concentrations of silver at lower levels can be immobilized into a wound bed using a polyelectrolyte multilayer attachment technology. These silver nanoparticle-impregnated polyelectrolyte multilayers are noncytotoxic yet bactericidal in vitro, but their effect on wound healing in vivo was previously unknown. The purpose of this study was to determine the effect on wound healing of integrating silver nanoparticle/polyelectrolyte multilayers into the wound bed. A full-thickness, splinted, excisional murine wound healing model was employed in both phenotypically normal mice and spontaneously diabetic mice (healing impaired model). Gross image measurements showed an initial small lag in healing in the silver-treated wounds in diabetic mice, but no difference in time to complete wound closure in either normal or diabetic mice. Histological analysis showed modest differences between silver-treated and control groups on day 9, but no difference between groups at the time of wound closure. We conclude that silver nanoparticle/polyelectrolyte multilayers can be safely integrated into the wound beds of both normal and diabetic mice without delaying wound closure, and with transient histological effects. The results of this study suggest the feasibility of this technology for use as a platform to affect nanoscale wound engineering approaches to microbial prophylaxis or to augment wound healing. PMID:23511285

Guthrie, Kathleen M; Agarwal, Ankit; Teixeira, Leandro B C; Dubielzig, Richard R; Abbott, Nicholas L; Murphy, Christopher J; Singh, Harpreet; McAnulty, Jonathan F; Schurr, Michael J

2013-01-01

137

A hermetic and room-temperature wafer bonding technique based on integrated reactive multilayer systems  

NASA Astrophysics Data System (ADS)

This paper focuses on direct deposition and patterning of reactive and nano-scale multilayer films at wafer level. These multilayer structures are called integrated reactive material systems (iRMS). In contrast to the typically used nickel (Ni)/ aluminum (Al) systems, in this work we needed to have our total multilayer film thicknesses smaller than 2.5?µm to reduce stress within the multilayer as well as deposition costs. Thus, we introduced new high energetic iRMS. These films were deposited by using alternating magnetron sputtering from high purity Al- and palladium (Pd)-targets to obtain films with a defined Al:Pd atomic ratio. In this paper, we present the result for reaction characteristics and reaction velocities which were up to 72.5?m?s?1 for bond frames with lateral dimensions as low as 20?µm. Furthermore, the feasibility of silicon (Si)–Si, Si–glass as well as Si–ceramic hermetic and metallic wafer bonding at room temperature is presented. We show that by using this bond technology, strong (maximum shear strengths of 235?MPa) and hermetically sealed bond interfaces can be achieved without any additional solder material.

Braeuer, J.; Gessner, T.

2014-11-01

138

Electronic transport in nanoscale structures  

NASA Astrophysics Data System (ADS)

In this dissertation electronic transport in nanoscale structures is discussed. An expression for the shot noise, a fluctuation in current due to the discreteness of charge, is derived directly from the wave functions of a nanoscale system. Investigation of shot noise is of particular interest due to the rich fundamental physics involved. For example, the study of shot noise can provide fundamental insight on the nature of electron transport in a nanoscale junction. We report calculations of the shot noise properties of parallel wires in the regime in which the interwire distance is much smaller than the inelastic mean free path. The validity of quantized transverse momenta in a nanoscale structure and its effect on shot noise is also discussed. We theoretically propose and show the feasibility of a novel protocol for DNA sequencing based on the electronic signature of single-stranded DNA while it translocates through a nanopore. We find that the currents for the bases are sufficiently different to allow for efficient sequencing. Our estimates reveal that sequencing of an entire human genome could be done with very high accuracy in a matter of hours, e.g., orders of magnitude faster than present techniques. We also find that although the overall magnitude of the current may change dramatically with different detection conditions, the intrinsic distinguishability of the bases is not significantly affected by pore size and transverse field strength. Finally, we study the ability of water to screen charges in nanopores by using all-atom molecular dynamics simulations coupled to electrostatic calculations. Due to the short length scales of the nanopore geometry and the large local field gradient of a single ion, the energetics of transporting an ion through the pore is strongly dependent on the microscopic details of the electric field. We show that as long as the pore allows the first hydration shell to stay intact, e.g., ˜6 nearby water molecules, the electric field of the ion can be well screened. We also discuss the consequences of the formation of hydration layers and of the discrete nature of polarization at atomic length scales for the applicability of continuum dielectric models.

Lagerqvist, Johan

139

Controlling Magnetism at the Nanoscale  

NASA Astrophysics Data System (ADS)

In this thesis, we look at controlling the magnetic properties at the nano-scale in single crystal thin film through structural modifications and external static electric fields (i.e. magnetoelectric effects). The first part of the thesis focuses on changing the magnetic properties in thin films through sample structure modifications. The other half focuses on using static electric fields to tune the magnetic properties within magnetic thin films. We show that the magnetic anisotropy can be changes through the application of static electric fields. Most interestingly though, we find that the phase transition in magnetite can be tuned with electric fields leading to an enhanced magentoelectric effect.

Wong, Jared Jue

140

Nanoscale molecular-switch crossbar circuits  

Microsoft Academic Search

Molecular electronics offer an alternative pathway to construct nanoscale circuits in which the critical dimension is naturally associated with molecular sizes. We describe the fabrication and testing of nanoscale molecular-electronic circuits that comprise a molecular monolayer of [2]rotaxanes sandwiched between metal nanowires to form an 8 × 8 crossbar within a 1 µm2 area. The resistance at each cross point

Yong Chen; Gun-Young Jung; Douglas A. A. Ohlberg; Xuema Li; Duncan R. Stewart; Jan O. Jeppesen; Kent A. Nielsen; J. Fraser Stoddart; R. Stanley Williams

2003-01-01

141

The Center for Nanoscale Materials at Argonne  

E-print Network

at the nanoscale is changing the world of science--leading to The Center for Nanoscale Materials (CNM) at Argonne for interdisciplinary nanoscience and nanotechnology researchers can apply to use CNM for both nonproprietary The Center CNM to be similar to the cultural centers in Renaissance Europe boundaries of nanoscience." #12

Kemner, Ken

142

Oxygen Detection via Nanoscale Optical Indicators  

E-print Network

Oxygen Detection via Nanoscale Optical Indicators Ruby N. Ghosh Dept. of Physics Michigan State University East Lansing, MI, USA weekschr@msu.edu Abstract--Oxygen plays a ubiquitous role in terrestrial developed an optical technique for monitoring oxygen in both gas and liquid phases utilizing nanoscale metal

Ghosh, Ruby N.

143

Force modulation for enhanced nanoscale electrical sensing  

Microsoft Academic Search

Scanning probe microscopy employing conductive probes is a powerful tool for the investigation and modification of electrical properties at the nanoscale. Application areas include semiconductor metrology, probe-based data storage and materials research. Conductive probes can also be used to emulate nanoscale electrical contacts. However, unreliable electrical contact and tip wear have severely hampered the widespread usage of conductive probes for

W. W. Koelmans; A. Sebastian; L. Abelmann; M. Despont; H. Pozidis

2011-01-01

144

Physics of polypeptide multilayer films.  

PubMed

Polypeptide multilayer films are promising for the development of coatings for implant devices, biosensors, and artificial cells. This paper discusses aspects of the physics of these films. Three sub-topics in the physics of peptide adsorption in multilayer film assembly covered here are peptide structure at the film/solid support interface, adsorbed layer thickness, and dynamics of peptide adsorption. A synopsis of work in these areas is preceded by an introduction to the subject and a review of some aspects of polymer theory. PMID:16447167

Haynie, Donald T

2006-08-01

145

Giant transverse optical forces in nanoscale slot waveguides of hyperbolic metamaterials.  

PubMed

Here we demonstrate that giant transverse optical forces can be generated in nanoscale slot waveguides of hyperbolic metamaterials, with more than two orders of magnitude stronger compared to the force created in conventional silicon slot waveguides, due to the nanoscale optical field enhancement and the extreme optical energy compression within the air slot region. Both numerical simulation and analytical treatment are carried out to study the dependence of the optical forces on the waveguide geometries and the metamaterial permittivity tensors, including the attractive optical forces for the symmetric modes and the repulsive optical forces for the anti-symmetric modes. The significantly enhanced transverse optical forces result from the strong optical mode coupling strength between two metamaterial waveguides, which can be explained with an explicit relation derived from the coupled mode theory. Moreover, the calculation on realistic metal-dielectric multilayer structures indicates that the predicted giant optical forces are achievable in experiments, which will open the door for various optomechanical applications in nanoscale, such as optical nanoelectromechanical systems, optical sensors and actuators. PMID:23037385

He, Yingran; He, Sailing; Gao, Jie; Yang, Xiaodong

2012-09-24

146

Multilayer insulation for spacecraft applications  

Microsoft Academic Search

Multilayer Insulation (MLI) blankets provide a lightweight insulation system with a high thermal resistance in vacuum. MLI blankets are utilized to reduce heat loss from a spacecraft to the cold space, or to prevent excessive heating of the surroundings from an internal component with heat dissipation. MLI blankets consist of a number of highly reflecting radiation shields interspaced with a

Che-Shing Kang

1999-01-01

147

Studies on the effect of dispersoid(ZrO2) in PVdF-co-HFP based gel polymer electrolytes  

NASA Astrophysics Data System (ADS)

Gel polymer electrolytes containing poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) / Lithium bis(trifluoromethane sulfon)imide (LiTFSI) / mixture of ethylene carbonate and propylene carbonate (EC+PC) with different concendration of ZrO2 has been prepared using the solution casting technique. The conductivity of the prepared electrolyte sample has been determined by AC impedance technique in the range 303-353K. The temperature dependent ionic conductivity plot seems to obey VTF relation. The maximum ionic conductivity value of 4.46 × 10-3S/cm has been obtained for PVdF-co-HFP(32%) - LiTFSI(8%) - EC+PC (60%) + ZrO2(6wt%) based polymer electrolyte. The surface morphology of the prepared electrolyte sample has been studied using SEM.

Sivakumar, M.; Subadevi, R.; Muthupradeepa, R.

2013-06-01

148

High performance EUV multilayer optics  

NASA Astrophysics Data System (ADS)

The demand for enhanced optical resolution in order to structure and observe ever smaller details has pushed optics development in recent years. There is increasing interest in optical components for the extreme ultraviolet (EUV) spectral region mainly as a result of the production of more powerful electronic circuits with the aid of projection lithography. Due to absorption at wavelengths below 100 nm the penetration depth of EUV radiation into matter is only a few nano-meters. Hence, reflective optics must be used for imaging and light collection such as EUV multilayer mirrors which consist of alternating thin films with different refractive indices. This basic idea can be compared to the classic, high reflective ?/4 systems: the constructive interference of all beams reflected at the film interfaces. At Fraunhofer IOF Jena multilayer optics development cover the full range between the soft X-rays around 2 nm wave-length and the vacuum ultraviolet. However, the paper will focus on multilayer optics for EUV lithography applications at 13.5 nm. Besides the development of high-reflective multilayers with enhanced thermal and radiation stability using interface engineering and optimized capping layers collector and imaging optics for diverse applications in the EUV spectral range have been realized. The deposition of EUV collector mirrors for high-power laser produced plasma (LPP) sources is discussed. The paper summarizes recent progress and the present knowledge in preparation and characterization of multilayer optics for the EUV spectral range with regard to maximum optical performance, minimization of structure imperfections, reduc-tion of residual stresses as well as enhanced thermal and radiation stability.

Kaiser, Norbert; Yulin, Sergiy; Perske, Marco; Feigl, Torsten

2008-09-01

149

Multilayer Composite Pressure Vessels  

NASA Technical Reports Server (NTRS)

A method has been devised to enable the fabrication of lightweight pressure vessels from multilayer composite materials. This method is related to, but not the same as, the method described in gMaking a Metal- Lined Composite-Overwrapped Pressure Vessel h (MFS-31814), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 59. The method is flexible in that it poses no major impediment to changes in tank design and is applicable to a wide range of tank sizes. The figure depicts a finished tank fabricated by this method, showing layers added at various stages of the fabrication process. In the first step of the process, a mandrel that defines the size and shape of the interior of the tank is machined from a polyurethane foam or other suitable lightweight tooling material. The mandrel is outfitted with metallic end fittings on a shaft. Each end fitting includes an outer flange that has a small step to accommodate a thin layer of graphite/epoxy or other suitable composite material. The outer surface of the mandrel (but not the fittings) is covered with a suitable release material. The composite material is filament- wound so as to cover the entire surface of the mandrel from the step on one end fitting to the step on the other end fitting. The composite material is then cured in place. The entire workpiece is cut in half in a plane perpendicular to the axis of symmetry at its mid-length point, yielding two composite-material half shells, each containing half of the foam mandrel. The halves of the mandrel are removed from within the composite shells, then the shells are reassembled and bonded together with a belly band of cured composite material. The resulting composite shell becomes a mandrel for the subsequent steps of the fabrication process and remains inside the final tank. The outer surface of the composite shell is covered with a layer of material designed to be impermeable by the pressurized fluid to be contained in the tank. A second step on the outer flange of each end fitting accommodates this layer. Depending on the application, this layer could be, for example, a layer of rubber, a polymer film, or an electrodeposited layer of metal. If the fluid to be contained in the tank is a gas, then the best permeation barrier is electrodeposited metal (typically copper or nickel), which can be effective at a thickness of as little as 0.005 in (.0.13 mm). The electrodeposited metal becomes molecularly bonded to the second step on each metallic end fitting. The permeation-barrier layer is covered with many layers of filament-wound composite material, which could be the same as, or different from, the composite material of the inner shell. Finally, the filament-wound composite material is cured in an ov

DeLay, Tom

2005-01-01

150

Current noise in semiconductor nanoscale devices  

NASA Astrophysics Data System (ADS)

We discuss the current noise characteristics of nano-scale devices by employing the quantum transport models based upon the nonequilibrium Green's function model (NEGF) and the Monte Carlo (MC) device simulation. In this paper the NEGF is used to study the shot noise suppression caused by the quantum mechanical correlations of electrons in semiconductor nano-scale devices, so that the current noise is discussed at low temperature. On the other hand, the quantum corrected MC model is developed to simulate practical semiconductor devices at normal temperatures, and the current noise spectral density of a nano-scale Si-MOSFET structure is presented.

Miyoshi, Tanroku; Tsuchiya, Hideaki; Ogawa, Matsuto; Asanuma, Akihiko

2004-05-01

151

New directions for nanoscale thermoelectric materials research  

NASA Technical Reports Server (NTRS)

Many of the recent advances in enhancing the thermoelectric figure of merit are linked to nanoscale phenomena with both bulk samples containing nanoscale constituents and nanoscale materials exhibiting enhanced thermoelectric performance in their own right. Prior theoretical and experimental proof of principle studies on isolated quantum well and quantum wire samples have now evolved into studies on bulk samples containing nanostructured constituents. In this review, nanostructural composites are shown to exhibit nanostructures and properties that show promise for thermoelectric applications. A review of some of the results obtained to date are presented.

Dresselhaus, M. S.; Chen, G.; Tang, M. Y.; Yang, R. G.; Lee, H.; Wang, D. Z.; Ren, F.; Fleurial, J. P.; Gogna, P.

2005-01-01

152

Charge transport in nanoscale junctions.  

PubMed

Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at the molecular level. Nanoscale charge transport experiments in ionic liquids extend the field to high temperatures and to systems with intriguing interfacial potential distributions. Other directions may include dye-sensitized solar cells, new sensor applications and diagnostic tools for the study of surface-bound single molecules. Another motivation for this special issue is thus to highlight activities across different research communities with nanoscale charge transport as a common denominator. This special issue gathers 27 articles by scientists from the United States, Germany, the UK, Denmark, Russia, France, Israel, Canada, Australia, Sweden, Switzerland, the Netherlands, Belgium and Singapore; it gives us a flavour of the current state-of-the-art of this diverse research area. While based on contributions from many renowned groups and institutions, it obviously cannot claim to represent all groups active in this very broad area. Moreover, a number of world-leading groups were unable to take part in this project within the allocated time limit. Nevertheless, we regard the current selection of papers to be representative enough for the reader to draw their own conclusions about the current status of the field. Each paper is original and has its own merit, as all papers in Journal of Physics: Condensed Matter special issues are subjected to the same scrutiny as regular contributions. The Guest Editors have deliberately not defined the specific subjects covered in this issue. These came out logically from the development of this area, for example: 'Traditional' solid state nanojunctions based on adsorbed layers, oxide films or nanowires sandwiched between two electrodes: effects of molecular structure (aromaticity, anchoring groups), symmetry, orientation, dynamics (noise patterns) and current-induced heating. Various 'physical effects': inelastic tunnelling and Coulomb blockade, polaron effects, switching modes, and negative differential resistance; the role of many particle excitations, new surface states in semiconductor electrodes, various mechanisms for

Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

2008-09-01

153

STM Manipulation of Nanoscale Biomolecules  

NASA Astrophysics Data System (ADS)

The fascinating advances in single molecule manipulations with the scanning-tunneling-microscope (STM)-tip allow scientists to fabricate artificial atomic scale structures, to study local quantum phenomena or to investigate and control properties of molecules at an atomic limit. The STM manipulation is facilitated by a precise control of tip-molecule interactions, or tunneling electrons, or the electric field between the tip and sample. By combining STM manipulation with imaging and tunneling spectroscopy, powerful experimental schemes can be developed, which opens novel routes to investigate or induce molecular conformation changes with atomic level control. In this talk, various cutting-edge STM manipulation techniques relevant to the biological systems will be introduced and our recent results on manipulation of nanoscale biological molecules including chlorophyll-a, ?-carotene and amyloid ?/A4 precursor protein on a Au(111) substrate will be presented.

Hla, Saw-Wai

2006-03-01

154

Optical Spectroscopy at the Nanoscale  

NASA Astrophysics Data System (ADS)

Recent advances in material science and fabrication techniques enabled development of nanoscale applications and devices with superior performances and high degree of integration. Exotic physics also emerges at nanoscale where confinement of electrons and phonons leads to drastically different behavior from those in the bulk materials. It is therefore rewarding and interesting to investigate and understand material properties at the nanoscale. Optical spectroscopy, one of the most versatile techniques for studying material properties and light-matter interactions, can provide new insights into the nanomaterials. In this thesis, I explore advanced laser spectroscopic techniques to probe a variety of different nanoscale phenomena. A powerful tool in nanoscience and engineering is scanning tunneling microscopy (STM). Its capability in atomic resolution imaging and spectroscopy unveiled the mystical quantum world of atoms and molecules. However identification of molecular species under investigation is one of the limiting functionalities of the STM. To address this need, we take advantage of the molecular `fingerprints' - vibrational spectroscopy, by combining an infrared light sources with scanning tunneling microscopy. In order to map out sharp molecular resonances, an infrared continuous wave broadly tunable optical parametric oscillator was developed with mode-hop free fine tuning capabilities. We then combine this laser with STM by shooting the beam onto the STM substrate with sub-monolayer diamondoids deposition. Thermal expansion of the substrate is detected by the ultrasensitive tunneling current when infrared frequency is tuned across the molecular vibrational range. Molecular vibrational spectroscopy could be obtained by recording the thermal expansion as a function of the excitation wavelength. Another interesting field of the nanoscience is carbon nanotube, an ideal model of one dimensional physics and applications. Due to the small light absorption with nanometer size, individual carbon nanotube is not visible under any conventional microscopy and characterization of individual nanotube becomes a focused research interest. Although electron microscopies and optical spectroscopies are developed previously to study carbon nanotubes, none of them permitted versatile imaging and spectroscopy of individual nanotube in a non-invasive, high throughput and ambient way. In this thesis a new polarization-based optical microscopy and spectroscopy is developed with exceedingly better contrast for one dimensional nano-materials and capability of individual carbon nanotube imaging and spectroscopy. This development provides a reliable way to measure the absolute absorption cross-section of individual chirality-defined carbon nanotubes. It also enables fast profiling for growth optimization and in situ characterization for functioning carbon nanotube devices. Two dimensional systems constitute another important family of nanomaterials, ranging from semi-metal (graphene), semiconductors (transition metal dichalcogenides) to insulators (h-BN). Despite of their scientific significance, they present a complete set of 2D building blocks for two dimensional electronics and optoelectronics. Heterostructures purely made of 2D thin films hold great promises due to functionality, scalability and ultrathin nature. Understanding the properties of the coupled heterolayers will be important and intriguing for these applications. With the advanced ultrafast laser spectroscopy, we study the dynamics of charge transfer process in two dimensional atomically thin semiconductors heterostructures. An extremely efficient charge transfer process is identified in atomically thin MoS2/WS2 system, which is expected to form a type-II heterojunction. Our discovery would greatly facilitate further studies of 2D materials as a photovoltaic device.

Hong, Xiaoping

155

Reactions inside nanoscale protein cages  

NASA Astrophysics Data System (ADS)

Chemical reactions are traditionally carried out in bulk solution, but in nature confined spaces, like cell organelles, are used to obtain control in time and space of conversion. One way of studying these reactions in confinement is the development and use of small reaction vessels dispersed in solution, such as vesicles and micelles. The utilization of protein cages as reaction vessels is a relatively new field and very promising as these capsules are inherently monodisperse, in that way providing uniform reaction conditions, and are readily accessible to both chemical and genetic modifications. In this review, we aim to give an overview of the different kinds of nanoscale protein cages that have been employed as confined reaction spaces.

Bode, Saskia A.; Minten, Inge J.; Nolte, Roeland J. M.; Cornelissen, Jeroen J. L. M.

2011-06-01

156

First Principles Modeling of Metal/Ceramic Multilayer Nano-heterostructures.  

SciTech Connect

Nanoscaled multilayer films composed of metals and ceramics have been explored for their potential applications as ductile, yet strong, materials. It is believed that at the nanoscale, the interfaces between the two materials constituting the multilayer assume an increasingly important role in determining the properties, as they comprise a more significant volume fraction of the multilayer with decreasing layer thickness. In this ab initio work, density functional theory was used to calculate the ideal shear strengths of pure Al, pure TiN, the Al/TiN interfacial region, and Al/TiN multilayers. The ideal shear strength of the Al/TiN interface was found to vary from very low (on the order of the ideal shear strength of Al) to very high (on the order of the ideal shear strength of TiN), depending on whether the TiN at the interface was Ti- or N-terminated, respectively. The results suggest that the shear properties of Al/TiN depend strongly on the chemistry of the interface, Al:N versus Al:Ti terminations. Nevertheless, for the Al/TiN multilayers, the ideal shear strength was limited by shear in the Al layer away from the interface, even when the individual layer thickness is less than a nanometer. Further we found an unusual structural rotation of bulk single-crystal Al under uniaxial compressive strains. It was found that under strains either along the <11-2> or the <111> directions, beyond a critical stress of about 13 GPa, the Al crystal can rotate through shear in the Shockley partial direction (i.e.,<11-2>) on the {l_brace}111{r_brace} plane, in an attempt to relieve internal stresses. This phenomenon reveals a possible mechanism leading to the onset of homogeneous dislocation nucleation in Al under high uniaxial compressions.

Yadav, Satyesh K. [Los Alamos National Laboratory; Wang, Jian [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory; Liu, Xiang-Yang [Los Alamos National Laboratory; Ramprasad, Ramamurthy [Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA

2012-07-31

157

Nanoscale science: Complex rules for soft systems  

NASA Astrophysics Data System (ADS)

The nanometre scale is a brave new world for scientists - mixing materials at such small dimensions can cause all sorts of surprising effects. New studies of experimental systems on the nanoscale further our understanding of these complex phenomena.

Glotzer, Sharon C.

2003-11-01

158

Nanoscale Science, Engineering and Technology Research Directions  

E-print Network

OF CONTENTS Basic Energy Sciences Nanoscience/Nanotechnology Group Basic Energy Sciences Nanoscience/Nanotechnology Group Chair: Douglas H. Lowndes (ORNL) A. Paul#12;#12;Nanoscale Science, Engineering and Technology Research Directions ABSTRACT This report

Wu, Zhigang

159

Anomalous magnetoresistance in Fibonacci multilayers.  

SciTech Connect

We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A. (Materials Science Division); (Universidade Federal do Rio Grande do Norte)

2012-01-01

160

Science and Technology at the Nanoscale  

NSDL National Science Digital Library

Northwestern University offers this graduate course on nanoscience to introduce students to the field. Taught by Professor Teri Odom, this course presents students with contemporary issues in nanoscience and nanotechnology as well as provide training on advanced nanoscale instrumentation. The website includes PDF lecture slideshows that provide more detailed information on subjects such as scanning probe microscopy, nanofabrication, and nanoscale electronics and photonics. This would be a good resource for teachers who want to incorporate nanoscience into their pre-existing chemistry classes.

Odom, Teri W.

2012-04-12

161

Multilayered regionalization in Northern Europe  

Microsoft Academic Search

The broadening and deepening of Europe as a macro-region impels processes of expansion, contraction and transformation in\\u000a sub-regions positioned within the EU and across the EU’s border. Recent arguments stress the idea of regionalization as a\\u000a multi-layered process. Using Northern Europe as a study site, three such layers are explored: territorially bounded regionalization\\u000a in the voting patterns of the Eurovision

Paul C. Adams

162

Ultra-thin multilayer capacitors.  

SciTech Connect

The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

Renk, Timothy Jerome; Monson, Todd C.

2009-06-01

163

Fe/Au Multilayers: Structure and Magnetoresistance  

SciTech Connect

We have measured the magnetoresistance (MR) in two sets of Fe/Au multilayers, with varying (1) Fe layer thickness, t{sub Fe} = 3-10 nm, and (2) Au layer thickness t{sub Au} = 5-15 nm, grown on Si substrates by sputtering. The multilayer interface structure and magnetic properties were studied by polarized neutron reflectometry (PNR). The study was undertaken to understand the correlation between structure of these multilayers and their magneto-transport properties.

Singh, Surendra; Basu, Saibal; Bhattacharya, D. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Prajapat, C. L. [Technical Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Gupta, M. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India)

2011-07-15

164

Multilayer Piezoelectric Ceramic Vibrator with Internal Electrodes  

Microsoft Academic Search

Multilayer piezoelectric vibrators made from high mechanical quality factor (Q m) PbZrTiO3 ceramic material with internal electrodes have been investigated for application to ultrasonic devices. The existence of internal electrodes activates the ceramic sintering reaction and as a result, cofiring of the the multilayer vibrator at a lower temperature becomes possible. Multilayer vibrators with 2-9 layers of internal electrodes were

Yoshiaki Fuda; Hiroshi Ono; Futoshi Shiotani; Katsunori Kumasaka

1995-01-01

165

75 FR 66126 - Multilayered Wood Flooring From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1179 (Preliminary)] Multilayered Wood Flooring From China AGENCY: United States...reason of imports from China of multilayered wood flooring, provided for in subheadings...of U.S. manufacturers of multilayered wood flooring. The following companies...

2010-10-27

166

76 FR 76435 - Multilayered Wood Flooring From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1179 (Final)] Multilayered Wood Flooring From China Determinations On the...those imports from China of multilayered wood flooring, provided for in subheadings...of U.S. manufacturers of multilayered wood flooring. The following companies...

2011-12-07

167

75 FR 79019 - Multilayered Wood Flooring From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1179 (Preliminary)] Multilayered Wood Flooring From China Determinations On the...reason of imports from China of multilayered wood flooring, provided for in subheadings...of U.S. manufacturers of multilayered wood flooring. The following companies...

2010-12-17

168

Nanoscale Architectures for Energy Applications  

NASA Astrophysics Data System (ADS)

In my group, we have developed a number of different potential architecture systems for gaining insights into energy storage and photovoltaics. In one manifestation of our efforts, generating a heterojunction comprising nanotubes and nanocrystals, externally bound and connected, has been significant. The unique, innovative, and important aspect of this particular nanoscale architecture is that it takes advantage of the tunability, in terms of size, shape, and chemistry, of nanotubes and nanocrystals, to create a sharp junction interface, whose properties are inherently manipulable, tailorable, and hence, predictable. For example, the electrical resistance of nanotube-nanoparticle networks is dependent on the nanoscale junctions that exist between these constituent nanomaterials as well as on microscale and macroscale connectivity. Thus, rational design of these nanomaterials is critical to a fundamental understanding of charge transport in single molecules and the determination of their conductance. Results on these systems can therefore be used to increase understanding of intrinsic factors affecting carrier mobility, such as electronic structure, carrier trapping, and delocalization. In a second manifestation, three-dimensional, dendritic micron- scale spheres of alkali metal hydrogen titanate 1D nanostructures (i.e.: nanowires and nanotubes) have been generated using a modified hydrothermal technique in the presence of hydrogen peroxide and an alkali metal hydroxide solution. Sea-urchin-like assemblies of these 1D nanostructures have been transformed into their hydrogen titanate analogues by neutralization as well as into their corresponding semiconducting, anatase titania nanostructured counterparts through a moderate high-temperature annealing dehydration process without destroying the 3D hierarchical structural motif. The as-prepared hollow spheres of titanate and titania 1D nanostructures have overall diameters, ranging from 0.8 ?m to 1.2 ?m, while the interior of these aggregates are vacuous with a diameter range of 100 to 200 nm. We have demonstrated that these assemblies are useful for example as active photocatalysts for the degradation of synthetic Procion Red dye under UV light illumination. In a third set of experiments, a size- and shape-dependent morphological transformation was demonstrated during the hydrothermal soft chemical transformation, in neutral solution, of titanate nanostructures into their anatase titania counterparts. Our results indicate that as-synthesized titania nanostructures possessed higher photocatalytic activity than the commercial titania precursors from whence they were derived.

Wong, Stanislaus

2009-03-01

169

Thermal stability, complexing behavior, and ionic transport of polymeric gel membranes based on polymer PVdF-HFP and ionic liquid, [BMIM][BF4].  

PubMed

PVdF-HFP + IL(1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF(4)]) polymeric gel membranes containing different amounts of ionic liquid have been synthesized and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR), differential scanning calorimetry, thermogravimetric analysis (TGA), and complex impedance spectroscopic techniques. Incorporation of IL in PVdF-HFP polymer changes different physicochemical properties such as melting temperature (T(m)), thermal stability, structural morphology, amorphicity, and ionic transport. It is shown by FTIR, TGA (also first derivative of TGA, "DTGA") that IL partly complexes with the polymer PVdF-HFP and partly remains dispersed in the matrix. The ionic conductivity of polymeric gel membranes has been found to increase with increasing concentration of IL and attains a maximum value of 1.6 × 10(-2) S·cm(-1) for polymer gel membrane containing 90 wt % IL at room temperature. Interestingly, the values of conductivity of membranes with 80 and 90 wt % of IL were higher than that of pure IL (100 wt %). The polymer chain breathing model has been suggested to explain it. The variation of ionic conductivity with temperature of these gel polymeric membranes follows Arrhenius type thermally activated behavior. PMID:23167848

Shalu; Chaurasia, S K; Singh, R K; Chandra, S

2013-01-24

170

Nanoscale Interfacial Friction and Adhesion on Supported versus Suspended Monolayer and Multilayer Graphene  

E-print Network

Graphene Zhao Deng,, Nikolai N. Klimov,,§ Santiago D. Solares,, Teng Li,, Hua Xu,, and Rachel J. Cannara Information ABSTRACT: Using atomic force microscopy (AFM), supported by semicontinuum numerical simulations and adhesion for suspended and silicon dioxide supported graphene of varying thickness. While pull-o force

Li, Teng

171

Study of nano-scale diffusion in thin films and multilayers  

Microsoft Academic Search

It is shown that x-ray reflectivity and x-ray fluorescence under standing wave conditions can be used to study atomic diffusion\\u000a with an accuracy of a fraction of a nanometer. Both the techniques can be made isotope selective by making use of nuclear\\u000a resonance scattering from a Mössbauer active isotope. The techniques have been used to study self-diffusion of Fe in

Ajay Gupta; Sujoy Chakravarty; Parasmani Rajput; Mukul Gupta; Rudolf Rüffer

2008-01-01

172

Study of nano-scale diffusion in thin films and multilayers  

Microsoft Academic Search

It is shown that x-ray reflectivity and x-ray fluorescence under standing wave conditions can be used to study atomic diffusion\\u000a with an accuracy of a fraction of a nanometer. Both the techniques can be made isotope selective by making use of nuclear\\u000a resonance scattering from a Mössbauer active isotope. The techniques have been used to study self-diffusion of Fe in

Ajay Gupta; Sujoy Chakravarty; Parasmani Rajput; Mukul Gupta; Rudolf Rüffer

173

Yield maps for nanoscale metallic multilayers Adrienne V. Lamm *, Peter M. Anderson  

E-print Network

for layer k (Ek, mk are Young's modulus and Poisson's ratio of layer k). The plastic strain is due of alternating phases that can plastically deform. The design parameters are volume fraction, bi-layer thickness], suppress plasticity [5­8], generate significant anelasticity [9,10], and even promote unique rolling

Anderson, Peter M.

174

Engineered interfaces and nano-scale thin films for solid oxide fuel cell electrolytes  

NASA Astrophysics Data System (ADS)

Solid state electrolytes with high oxygen ionic conductivity at low temperatures are required to develop cost effective and efficient solid oxide fuel cells. This study investigates the influence of engineered interfaces on the oxygen ionic conductivity of nano-scale multilayer thin film electrolytes. The epitaxial Sm2O3 doped CeO2 (SDC) and Sc2O3 stabilized ZrO2 (ScSZ) are selected as the alternative layers for the proposed multilayer thin film electrolyte based on the optimum structural, chemical, and electrical properties reported in the previous studies. The epitaxial SDC(111)/ScSZ(111) multilayer thin films are grown on high purity Al2O3(0001) substrates by oxygen-plasma assisted molecular beam epitaxy. Prior to the deposition of multilayers, the growth parameters are optimized for epitaxial CeO 2, ZrO2, SDC, and ScSZ thin films. The epitaxial orientation and surface morphology of CeO2 thin films shows dependency on the growth rate. Epitaxial CeO2(111) is obtained at relatively high growth rates (>9 A/min) at a substrate temperature of 650°C and an oxygen partial pressure of 2 x 10 -5 Torr. The same growth parameters are used for the deposition of ZrO2 thin films. ZrO2 exhibits both monoclinic and cubic phases, which is stabilized in the cubic structure by doping with Sc 2O3. The Sm and Sc evaporation rates are varied during the growth to obtain thin films of 15 mol % SmO1.5 doped CeO2 and 20 mol % ScO1.5 stabilized ZrO2, respectively. The SDC/ScSZ multilayer thin films are grown using the same growth parameters by varying the number of layers. The SDC/ScSZ multilayer thin films show significant enhancement in the oxygen ionic conductivity in comparison to single layer SDC and ScSZ thin films. The increase in the oxygen ionic conductivity with the increase in number of layers can be attributed to lattice mismatch induced ionic conductivity along the interfaces. The 8-layer film exhibits the maximum oxygen ionic conductivity with one order of magnitude enhancement in the temperature range of 500-800°C compared to single layer thin films.

Nandasiri, Manjula I.

175

Nanoscale Mixing of Soft Solids  

SciTech Connect

Assessing the state of mixing on the molecular scale in soft solids is challenging. Concentrated solutions of micelles formed by self-assembly of polystyrene-block-poly(ethylene-alt-propylene) (PS-PEP) diblock copolymers in squalane (C{sub 30}H{sub 62}) adopt a body-centered cubic (bcc) lattice, with glassy PS cores. Utilizing small-angle neutron scattering (SANS) and isotopic labeling ({sup 1}H and {sup 2}H (D) polystyrene blocks) in a contrast-matching solvent (a mixture of squalane and perdeuterated squalane), we demonstrate quantitatively the remarkable fact that a commercial mixer can create completely random mixtures of micelles with either normal, PS(H), or deuterium-labeled, PS(D), cores on a well-defined bcc lattice. The resulting SANS intensity is quantitatively modeled by the form factor of a single spherical core. These results demonstrate both the possibility of achieving complete nanoscale mixing in a soft solid and the use of SANS to quantify the randomness.

Choi, Soo-Hyung; Lee, Sangwoo; Soto, Haidy E.; Lodge, Timothy P.; Bates, Frank S. (UMM); (Texas)

2013-03-07

176

Molecular Photovoltaics in Nanoscale Dimension  

PubMed Central

This review focuses on the intrinsic charge transport in organic photovoltaic (PVC) devices and field-effect transistors (SAM-OFETs) fabricated by vapor phase molecular self-assembly (VP-SAM) method. The dynamics of charge transport are determined and used to clarify a transport mechanism. The 1,4,5,8-naphthalene-tetracarboxylic diphenylimide (NTCDI) SAM devices provide a useful tool to study the fundamentals of polaronic transport at organic surfaces and to discuss the performance of organic photovoltaic devices in nanoscale. Time-resolved photovoltaic studies allow us to separate the charge annihilation kinetics in the conductive NTCDI channel from the overall charge kinetic in a SAM-OFET device. It has been demonstrated that tuning of the type of conductivity in NTCDI SAM-OFET devices is possible by changing Si substrate doping. Our study of the polaron charge transfer in organic materials proposes that a cation-radical exchange (redox) mechanism is the major transport mechanism in the studied SAM-PVC devices. The role and contribution of the transport through delocalized states of redox active surface molecular aggregates of NTCDI are exposed and investigated. This example of technological development is used to highlight the significance of future technological development of nanotechnologies and to appreciate a structure-property paradigm in organic nanostructures. PMID:21339983

Burtman, Vladimir; Zelichonok, Alexander; Pakoulev, Andrei V.

2011-01-01

177

Complementary techniques for the characterization of thin film Ti/Nb multilayers.  

PubMed

An aberration corrector on the probe-forming lens of a scanning TEM (STEM) equipped with an electron energy-loss spectrometer (EELS) and X-ray energy-dispersive spectrometer (XEDS) has been employed to investigate the compositional variations as a function of length scale in nanoscale Ti/Nb metallic multilayers. The composition profiles of EELS and XEDS were compared with the profiles obtained from the complementary technique of 3D atom probe tomography. At large layer widths (h > or = 7 nm, where h is the layer width) of Ti and Nb, XEDS composition profiles of Ti/Nb metallic multilayers are in good agreement with the EELS results. However, at reduced layer widths (h approximately 2 nm), profiles of EELS and atom probe exhibited similar compositional variations, whereas XEDS results have shown a marked difference. This difference in the composition profiling of the layers has been addressed with reference to the effects of beam broadening and the origin of the signals collected in these techniques. The advantage of using EELS over XEDS for these nanoscaled multilayered materials is demonstrated. PMID:19553019

Genç, Arda; Banerjee, Rajarshi; Thompson, Gregory B; Maher, Dennis M; Johnson, Andrew W; Fraser, Hamish L

2009-09-01

178

High performance multilayered nano-crystalline silicon/silicon-oxide light-emitting diodes on glass substrates.  

PubMed

A low-temperature hydrogenation-assisted sequential deposition and crystallization technique is reported for the preparation of nano-scale silicon quantum dots suitable for light-emitting applications. Radio-frequency plasma-enhanced deposition was used to realize multiple layers of nano-crystalline silicon while reactive ion etching was employed to create nano-scale features. The physical characteristics of the films prepared using different plasma conditions were investigated using scanning electron microscopy, transmission electron microscopy, room temperature photoluminescence and infrared spectroscopy. The formation of multilayered structures improved the photon-emission properties as observed by photoluminescence and a thin layer of silicon oxy-nitride was then used for electrical isolation between adjacent silicon layers. The preparation of light-emitting diodes directly on glass substrates has been demonstrated and the electroluminescence spectrum has been measured. PMID:21860083

Darbari, S; Shahmohammadi, M; Mortazavi, M; Mohajerzadeh, S; Abdi, Y; Robertson, M; Morrison, T

2011-09-16

179

Numerical investigations of failure in EB-PVD thermal barrier coating systems  

NASA Astrophysics Data System (ADS)

Thermal barrier coating (TBC) systems are used in high temperature applications in turbine engines. TBCs are applied on superalloy substrates and are multilayered coatings comprised of a metallic bond coat, a thermally grown oxide (TGO) and a ceramic top coat. They provide thermal protection for the superalloy substrate and are considered to hold the greatest potential for increased operating temperatures. Failure of the TBC system most commonly occurs as a result of large scale buckling and spallation. The buckling is a consequence of many small-scale delaminations that arise in the top coat above local imperfections in the TGO, and durability of the TBC system is governed by a sequence of crack nucleation, propagation and coalescence. The numerical investigations that are employed in this dissertation are used to determine the stress development near the imperfections and are based on microstructural observations and measured material properties of TBC test buttons supplied by GE Aircraft Engines. The test buttons were subject to thermal cycling at GE and cycled to different percentages of TBC life. Numerical simulations of two different types of TBC tests are used to show that the top coat out-of-plane stress increases with a decrease of the substrate radius of curvature and a decrease in the heating rate. An inherent scaling parameter in the TBC system is identified and used to demonstrate that the stress developed in the top coat is governed by the evolution of an imperfection in the TGO. The effect of a martensitic phase transformation in the bond coat, related to a change in bond coat chemistry, is shown to significantly increase the top coat out-of-plane tensile stress. Finally, a subsurface crack is simulated in the top coat and used to determine the influence of the bond coat on failure of the TBC system. While the bond coat inelastic properties are the most important factors in determining the extent of the crack opening displacement, the bond coat martensitic phase transformation governs when the crack propagates. The crack propagates during heat-up when the martensitic phase transformation is included, and it propagates during cool-down when the transformation is not included.

Glynn, Michael L.

180

LCA of biodegradable multilayer film from biopolymers  

Microsoft Academic Search

Multilayer films exhibit excellent properties for food packaging. However, existing products are not biodegradable. Conventional plastics, manufactured from fossil fuels, not only consume non-renewable and finite resources, but also impact heavily on waste disposal. A new multilayer film has been developed in the Multibio Project for the production of food packaging. In this paper, the environmental impacts of this new

Daniel Garraín; Rosario Vidal; Pilar Martínez; Vicente Franco; David Cebrián-Tarrasón

181

Multi-Layer E-Textile Circuits  

NASA Technical Reports Server (NTRS)

Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

2012-01-01

182

Plasmon bands in multilayer graphene  

NASA Astrophysics Data System (ADS)

High-energy collective electronic excitations (plasmons) in freestanding multilayer graphene are studied by momentum-resolved electron energy-loss spectroscopy (EELS). For normal incidence, only the high-energy plasmon band is excited and we measure a blueshift of the ? -plasmon dispersion with increasing thickness. The observed transition between two-dimensional and three-dimensional behavior is explained using a layered-electron-gas (LEG) model. We propose a method to measure all individual plasmon bands by tilting the sample with respect to the electron beam. As a proof of concept, EELS experiments for three-layer graphene are compared with predictions from the LEG model.

Wachsmuth, P.; Hambach, R.; Benner, G.; Kaiser, U.

2014-12-01

183

Understanding multilayers from a geometrical viewpoint.  

PubMed

We reelaborate on the basic properties of lossless multilayers. We show that the transfer matrices for these multilayers have essentially the same algebraic properties as the Lorentz group SO(2, 1) in a (2 + 1)-dimensional space-time as well as the group SL(2, R) underlying the structure of the ABCD law in geometrical optics. By resorting to the Iwasawa decomposition, we represent the action of any multilayer as the product of three matrices of simple interpretation. This group-theoretical structure allows us to introduce bilinear transformations in the complex plane. The concept of multilayer transfer function naturally emerges, and its corresponding properties in the unit disk are studied. We show that the Iwasawa decomposition is reflected at this geometrical level in three simple actions that can be considered the basic pieces for a deeper understanding of the multilayer behavior. We use the method to analyze in detail a simple practical example. PMID:11876327

Yonte, Teresa; Monzón, Juan J; Sánchez-Soto, Luis L; Cariñena, José F; López-Lacasta, Carlos

2002-03-01

184

Metallurgical phases and their magnetism at the interface of nanoscale MgB2/Fe layered structures.  

PubMed

We report on the characterization of metallurgical phases and their magnetism at the interfaces of nanoscale MgB(2)/Fe layered structures. MgB(2)/(57)Fe multilayers with varying layer thicknesses were prepared by vacuum deposition and investigated, before and after annealing by electrical resistance measurements, x-ray diffraction and (57)Fe conversion-electron Mössbauer spectroscopy (CEMS) down to 5 K. Interfacial Fe-B phases, such as Fe(2)B, were identified by CEMS. A superparamagnetic-to-ferromagnetic transition is observed with increasing (57)Fe film thickness. Ultrahigh vacuum annealing at 500 °C of the multilayers leads to strong diffusion of Fe atoms into the boundary regions of the MgB(2) layers. MgB(2) in the as-grown multilayers is non-superconducting. Structural disorder and the effect of Fe interdiffusion contribute to the suppression of superconductivity in the MgB(2) films of all the as-grown multilayers and the thinner annealed multilayers. However, an annealed MgB(2)/(57)Fe/MgB(2) trilayer with thicker (500 Å) MgB(2) layers is observed to be superconducting with an onset temperature of 25 K. At 5 K, the annealed trilayer can be conceived as being strongly chemically modulated, consisting of two partially Fe-doped superconducting MgB(2) layers separated by an interdiffused weakly magnetic Fe-B interlayer, which is characterized by a low hyperfine magnetic field B(hf) of ?11 T. This chemically modulated layer structure of the trilayer after annealing was verified by Rutherford backscattering. PMID:22076071

Sahoo, B; Keune, W; Kuncser, V; Becker, H-W; Röhlsberger, R

2011-11-30

185

Nanoscale assemblies and their biomedical applications  

PubMed Central

Nanoscale assemblies are a unique class of materials, which can be synthesized from inorganic, polymeric or biological building blocks. The multitude of applications of this class of materials ranges from solar and electrical to uses in food, cosmetics and medicine. In this review, we initially highlight characteristic features of polymeric nanoscale assemblies as well as those built from biological units (lipids, nucleic acids and proteins). We give special consideration to protein nanoassemblies found in nature such as ferritin protein cages, bacterial microcompartments and vaults found in eukaryotic cells and designed protein nanoassemblies, such as peptide nanofibres and peptide nanotubes. Next, we focus on biomedical applications of these nanoscale assemblies, such as cell targeting, drug delivery, bioimaging and vaccine development. In the vaccine development section, we report in more detail the use of virus-like particles and self-assembling polypeptide nanoparticles as new vaccine delivery platforms. PMID:23303217

Doll, Tais A. P. F.; Raman, Senthilkumar; Dey, Raja; Burkhard, Peter

2013-01-01

186

Force modulation for enhanced nanoscale electrical sensing.  

PubMed

Scanning probe microscopy employing conductive probes is a powerful tool for the investigation and modification of electrical properties at the nanoscale. Application areas include semiconductor metrology, probe-based data storage and materials research. Conductive probes can also be used to emulate nanoscale electrical contacts. However, unreliable electrical contact and tip wear have severely hampered the widespread usage of conductive probes for these applications. In this paper we introduce a force modulation technique for enhanced nanoscale electrical sensing using conductive probes. This technique results in lower friction, reduced tip wear and enhanced electrical contact quality. Experimental results using phase-change material stacks and platinum silicide conductive probes clearly demonstrate the efficacy of the proposed technique. Furthermore, conductive-mode imaging experiments on specially prepared platinum/carbon samples are presented to demonstrate the widespread applicability of this technique. PMID:21821873

Koelmans, W W; Sebastian, A; Abelmann, L; Despont, M; Pozidis, H

2011-09-01

187

Bench-scale synthesis of nanoscale materials  

NASA Technical Reports Server (NTRS)

A novel flow-through hydrothermal method used to synthesize nanoscale powders is introduced by Pacific Northwest Laboratory. The process, Rapid Thermal Decomposition of precursors in Solution (RTDS), uniquely combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was initially demonstrated on a laboratory scale and was subsequently scaled up to accommodate production rates attractive to industry. The process is able to produce a wide variety of metal oxides and oxyhydroxides. The powders are characterized by scanning and transmission electron microscopic methods, surface-area measurements, and x-ray diffraction. Typical crystallite sizes are less than 20 nanometers, with BET surface areas ranging from 100 to 400 sq m/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO2 produced by RTDS are included.

Buehler, M. F.; Darab, J. G.; Matson, D. W.; Linehan, J. C.

1994-01-01

188

Atomistic Design and Simulations of Nanoscale Machines and Assembly  

NASA Technical Reports Server (NTRS)

Over the three years of this project, we made significant progress on critical theoretical and computational issues in nanoscale science and technology, particularly in:(1) Fullerenes and nanotubes, (2) Characterization of surfaces of diamond and silicon for NEMS applications, (3) Nanoscale machine and assemblies, (4) Organic nanostructures and dendrimers, (5) Nanoscale confinement and nanotribology, (6) Dynamic response of nanoscale structures nanowires (metals, tubes, fullerenes), (7) Thermal transport in nanostructures.

Goddard, William A., III; Cagin, Tahir; Walch, Stephen P.

2000-01-01

189

Polyelectrolyte Multilayers in Tissue Engineering  

PubMed Central

The layer-by-layer assembly of sequentially adsorbed, alternating polyelectrolytes has become increasingly important over the past two decades. The ease and versatility in assembling polyelectrolyte multilayers (PEMs) has resulted in numerous wide ranging applications of these materials. More recently, PEMs are being used in biological applications ranging from biomaterials, tissue engineering, regenerative medicine, and drug delivery. The ability to manipulate the chemical, physical, surface, and topographical properties of these multilayer architectures by simply changing the pH, ionic strength, thickness, and postassembly modifications render them highly suitable to probe the effects of external stimuli on cellular responsiveness. In the field of regenerative medicine, the ability to sequester growth factors and to tether peptides to PEMs has been exploited to direct the lineage of progenitor cells and to subsequently maintain a desired phenotype. Additional novel applications include the use of PEMs in the assembly of three-dimensional layered architectures and as coatings for individual cells to deliver tunable payloads of drugs or bioactive molecules. This review focuses on literature related to the modulation of chemical and physical properties of PEMs for tissue engineering applications and recent research efforts in maintaining and directing cellular phenotype in stem cell differentiation. PMID:21210759

Detzel, Christopher J.; Larkin, Adam L.

2011-01-01

190

Nanoscale Physics The Wiess School of Natural Sciences  

E-print Network

Nanoscale Physics The Wiess School of Natural Sciences Degrees Offered: MS Rice University, and marketing of new science-based products. Degree Requirements for the MS in Nanoscale Physics In addition;2 Departments / Nanoscale Physics Science core courses: PHYS 533 Nanostructures and Nanotechnology I PHYS 539

Richards-Kortum, Rebecca

191

Nanoscale Physics The Wiess School of Natural Sciences  

E-print Network

249 Nanoscale Physics The Wiess School of Natural Sciences Degrees Offered: MS Rice University, and marketing of new science-based products. Degree Requirements for the MS in Nanoscale Physics In addition introduced the professional master's degree in nanoscale physics in fall 2002. This program combines a strong

Richards-Kortum, Rebecca

192

Nano-scale Sensor Networks for Chemical Eisa Zarepour1  

E-print Network

Nano-scale Sensor Networks for Chemical Catalysis Eisa Zarepour1 Mahbub Hassan1 Chun Tung Chou1- searchers are now investigating the viability of nano-scale sensor networks (NSNs), which are formed natural gas to liquid fuel. Given that reliable wireless communi- cation at nano-scale is at very early

New South Wales, University of

193

Nanoscale Volcanoes: Accretion of Matter at Ion Sculpted Nanopores  

E-print Network

Nanoscale Volcanoes: Accretion of Matter at Ion Sculpted Nanopores Toshiyuki Mitsui, Derek Stein demonstrate the formation of nanoscale volcano-like structures induced by ion beam irradiation of nanoscale pores in freestanding silicon nitride membranes. Accreted matter is delivered to the volcanoes from

Golovchenko, Jene A.

194

Effects of induced birefringence in nanoscale heterostructures  

NASA Astrophysics Data System (ADS)

The influence of a complex of elastic strains caused by technological stresses and external shear strains on the optical properties of cubic crystals has been analyzed. Data on the changes in optical symmetry of such crystals have been obtained. The changes in polarization characteristics of the radiation during propagation in both strained crystal and shear-strained nanoscale heterostructures have been studied. The effects of the acoustoelectronic and photoelastic deformation mechanisms on the changes in polarization properties of the radiation of nanoscale heterostructures have been compared.

Kulakova, L. A.

2014-12-01

195

Nanoscale Transistors: Advanced VLSI Devices (Introductory Lecture)  

NSDL National Science Digital Library

Contributed by Mark Lundstrom of Purdue University, this introductory lecture to nanoscale transistors is available both as a Flash video with audio and as presentation slides in PDF form (the links to these are on the right hand side of the page). The lecture introduces the course, which "examines the device physics of advanced transistors and the process, device, circuit, and systems considerations that enter into the development of new integrated circuit technologies." This is a helpful resource for nanotechnology instructors looking to introduce the concept of nanoscale transistors into their classrooms. For more from this course (lectures, assignments, etc.) click the Course Information Website link.

Lundstrom, Mark

196

An X-ray grazing incidence phase multilayer grating  

Microsoft Academic Search

An X-ray grazing incidence phase multilayer grating, representing a thin grating placed on a multilayer mirror, is proposed. A high efficiency of grating diffraction can be obtained by the possibility of changing the phase shift of the wave diffracted from the multilayer under the Bragg and total external reflection conditions. A grazing incidence phase multilayer grating consisting of Pt grating

V. A. Chernov; N. V. Kovalenko; S. V. Mytnichenko

2001-01-01

197

Magnetic properties of nanoscale conductors  

NASA Astrophysics Data System (ADS)

This doctoral dissertation examines some magnetic properties of nanoscale conductors. It comprises two classes of problems, namely, the response of closed nanoscopic systems to an external magnetic field, and the magnetization dependent transport of nanomagnets. In the first class of closed nanoscopic structures like quantum dots or metal grains, the system has discrete energy levels which can be modeled by Random Matrix Theory. The addition of a magnetic field is analyzed using a crossover random matrix model. In Chapter 2, we show that in the crossover there exist correlations between elements of the same eigenvector and between different eigenvectors. We show that these correlations between different eigenvectors lead to enhanced fluctuations of the electron-electron interaction matrix elements which are absent in the pure ensembles. In Chapter 3, we generalize these results to analyze the magnetic field response of energy levels in ultrasmall metal grains. We present a theory of mesoscopic fluctuations of g tensors and avoided crossing energies in a, small metal grain that contains both orbital and spin contributions to the g tensor. In the second class of problems we study two effects in small ferromagnets where the charge transport is coupled to the magnetization. In Chapter 4, we show that a sufficiently large unpolarized current can cause a spin-wave instability in a nanomagnet with asymmetric contacts. The dynamics beyond the instability is calculated analytically in the perturbative regime of small spinwave amplitudes, and numerically for larger currents. In Chapter 5, we study "anisotropic magnetoresistance fluctuations" which is the ferromagnetic analog of the well-known Universal Conductance; Fluctuations in metals. The conductance of a ferromagnetic particle depends on the relative orientation of the magnetization with respect to the direction of current flow. This phenomenon is known as "anisotropic magnetoresistance" and has no counterpart in normal-metal conductors. We show that quantum interference leads to an additional, random yet (statistically) universal dependence of the conductance of a ferromagnet on the magnetization direction. The mechanism for these anisotropic magnetoresistance fluctuations is the interplay of spin-orbit scattering, random impurity scattering, and the ferromagnet's exchange field.

Adam, Shaffique

198

Designing a Multicellular Organotypic 3D Liver Model with a Detachable, Nanoscale Polymeric Space of Disse  

PubMed Central

The design of in vitro models that mimic the stratified multicellular hepatic microenvironment continues to be challenging. Although several in vitro hepatic cultures have been shown to exhibit liver functions, their physiological relevance is limited due to significant deviation from in vivo cellular composition. We report the assembly of a novel three-dimensional (3D) organotypic liver model incorporating three different cell types (hepatocytes, liver sinusoidal endothelial cells, and Kupffer cells) and a polymeric interface that mimics the Space of Disse. The nanoscale interface is detachable, optically transparent, derived from self-assembled polyelectrolyte multilayers, and exhibits a Young's modulus similar to in vivo values for liver tissue. Only the 3D liver models simultaneously maintain hepatic phenotype and elicit proliferation, while achieving cellular ratios found in vivo. The nanoscale detachable polymeric interfaces can be modulated to mimic basement membranes that exhibit a wide range of physical properties. This facile approach offers a versatile new avenue in the assembly of engineered tissues. These results demonstrate the ability of the tri-cellular 3D cultures to serve as an organotypic hepatic model that elicits proliferation and maintenance of phenotype and in vivo-like cellular ratios. PMID:23556413

Larkin, Adam L.; Rodrigues, Richard R.; Murali, T.M.

2013-01-01

199

Innovative multilayer coated optics for Solar Physics  

NASA Astrophysics Data System (ADS)

Development of multilayer coated optics with specific spectral characteristics and enhanced temporal, thermal and radiation stability requires an innovative approach to the design of reflecting multilayers and optimization of the coating process. Here we report on the progress in design, calculations and fabrication of reflecting multilayer coatings for solar imaging in the extreme ultra-violet (EUV) range. We will present recent results of characterization of new tri-component periodic multilayer structures containing aluminum as a low absorbing material within the spectral range from 17 to 40 nm. The EUV peak reflectance of these coatings (for instance, the Al/Mo/SiC multilayers) reaches 56% at 17.4 nm and 42% at 30 nm, highest reported up to now for these wavelengths. We have studied the temporal and thermal stability of structural and optical parameters of Al-based multilayer coatings as well as the resistivity of the coatings to high-energy and high-dose proton irradiation. A special attention will be drawn to specific bi-periodic systems with enhanced selectivity, which possess two efficient reflection bands and attenuate some unwanted emission lines in the EUV range. Experimental results show that such multilayer coatings are good candidates for the EUV imaging telescopes of Solar Orbiter and future solar missions.

Meltchakov, Evgueni; Auchere, Frederic; Delmotte, Franck; De Rossi, Sebastien; Mercier, Raymond; Zhang, Xueyan

200

Near field imaging from multilayer lens.  

PubMed

Multilayer superlens has been reported that it had advantages over the single metal layer superlens. In this work, single silver layer and Ag-SiO2 multilayer superlens devices working at wavelength of 365 nm were fabricated using standard photolithography method. Grating objects with line/space (190 nm/190 nm) resolution could be resolved through both kinds of lens structures with working distance up to 128 nm. However, Ag-SiO2 multilayer lens shows higher transmittance and image contrast than the single silver layer device, the experimental result proves the theoretical calculation. PMID:22408982

Li, Guixin; Li, Jensen; Tam, H L; Chan, C T; Cheah, K W

2011-12-01

201

Coordination chemistry of verdazyl radicals: group 12 metal (Zn, Cd, Hg) complexes of 1,4,5,6-tetrahydro-2,4-dimethyl-6-(2 pyridiyl)-1,2,4,5-tetrazin -3(2H)-one (pvdH3) and 1,5-dimethyl-3-(2 pyridil)-6-oxoverdazyl (pvd).  

PubMed

Ferricyanide oxidation of 1,4,5,6-tetrahydro-2,4-dimethyl-6-(2'-pyridyl)-1,2,4,5-tetrazin-3(2H)-one (pvdH3) produces the stable chelating free radical 1,5-dimethyl-3-(2'-pyridyl)-6-oxoverdazyl (pvd) as an orange solid. Combination of group 12 metal halides with the ligand pvdH3 in acetonitrile results in precipitation of metal complexes. The mercuric chloride complex crystallizes in the monoclinic space group P2(1/c) with unit cell dimensions a = 8.5768(8) A, b = 19.1718(17) A, c = 8.5956(8) A, beta = 90.405 degrees, and V = 1413.4(2) A3. The mercuric ion is tricoordinate with a distorted trigonal planar geometry. Cadmium iodide and zinc chloride induce ring opening of the tetrazine resulting in pentacoordinate complexes of a hydrazone ligand. The cadmium iodide complex crystallizes in the triclinic space group P1 with cell dimensions a = 7.7184(8) A, b = 8.0240(9) A, c = 13.348(2) A, alpha = 97.876(4) degrees, beta = 95.594(6) degrees, gamma = 107.304(6) degrees, and V = 773.40(21) A3. Oxidation of all three metal complexes produces verdazyl radicals. Metal coordination is indicated by small changes in the EPR spectrum and by changes in the UV-visible spectrum, in particular the changes in the position of bands in the visible region. The metal halide-pvd complexes can also be synthesized by direct combination of metal halides with the free radical. PMID:11229577

Brook, D J; Fornell, S; Stevens, J E; Noll, B; Koch, T H; Eisfeld, W

2000-02-01

202

Center for Nanoscale Materials Strategic Plan  

E-print Network

Materials (CNM) is at the forefront of discovery research that addresses its cross-cutting scientific theme of Energy and Information Transduction at the Nanoscale. The CNM is an integral part of the National mitigation, transmission, storage, and energy efficiency. The CNM research vision also guides and shapes our

Kemner, Ken

203

Dynamic structural disorder in supported nanoscale catalysts  

SciTech Connect

We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.

Rehr, J. J.; Vila, F. D. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)] [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)

2014-04-07

204

ELECTROSTATIC FORCE MICROSCOPY STUDIES OF NANOSCALE SYSTEMS  

E-print Network

ELECTROSTATIC FORCE MICROSCOPY STUDIES OF NANOSCALE SYSTEMS A Thesis Submitted to the Faculty. Their helpful comments and insight have made considerable advancements in the understanding of electrostatic OF ELECTROSTATIC FORCE MICROSCOPY : : : : : : : : : 4 2.1 Origin of the Contact Potential Difference

205

Nanoscale Thermal Transport andMicrorefrigeratorsonaChip  

E-print Network

and quantum dot thermoelectrics as well as solid-state thermionic thin-film devices with embedded metallic); embedded nanoparti- cles; microrefrigeration; nanoscale heat transport; nanotech- nology; quantum dots. Experimental results have shown that phonon surface and interface scattering can lower thermal con- ductivity

206

Fats, Oils, and Colors of Nanoscale Materials  

NSDL National Science Digital Library

Phase changes and intermolecular forces are important physical science concepts but are not always easy to present in an active learning format. This article presents several interactive activities in which students plot the melting points of some fatty acids and explore the effect that the nanoscale size and shape of molecules have on the material's macroscopic phase properties.

Horoszewski, Dana; Lisensky, George C.; Zenner, Greta M.; Gentry, Kenneth L.; Crone, Wendy C.

2006-12-01

207

Dynamic structural disorder in supported nanoscale catalysts.  

PubMed

We investigate the origin and physical effects of "dynamic structural disorder" (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale. PMID:24712802

Rehr, J J; Vila, F D

2014-04-01

208

Traceable nanoscale measurement at NML-SIRIM  

SciTech Connect

The role of national metrology institute (NMI) has always been very crucial in national technology development. One of the key activities of the NMI is to provide traceable measurement in all parameters under the International System of Units (SI). Dimensional measurement where size and shape are two important features investigated, is one of the important area covered by NMIs. To support the national technology development, particularly in manufacturing sectors and emerging technology such nanotechnology, the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), has embarked on a project to equip Malaysia with state-of-the-art nanoscale measurement facility with the aims of providing traceability of measurement at nanoscale. This paper will look into some of the results from current activities at NML-SIRIM related to measurement at nanoscale particularly on application of atomic force microscope (AFM) and laser based sensor in dimensional measurement. Step height standards of different sizes were measured using AFM and laser-based sensors. These probes are integrated into a long-range nanoscale measuring machine traceable to the international definition of the meter thus ensuring their traceability. Consistency of results obtained by these two methods will be discussed and presented. Factors affecting their measurements as well as their related uncertainty of measurements will also be presented.

Dahlan, Ahmad M.; Abdul Hapip, A. I. [National Metrology Laboratory SIRIM Berhad (NML-SIRIM), Lot PT 4803, Bandar Baru Salak Tinggi, 43900 Sepang (Malaysia)

2012-06-29

209

Designing Functional Nanoscale Materials and Structures  

Microsoft Academic Search

In the presentation, I shall discuss about the recent results from our laboratory on the development of newer forms of lithography, synthesis of nanoscale particles and composites, and their applications in developing principles for sensors and actuators. The talk will also delve into the newer principles of designing chemical locomotives. Some of the resent results of nanobiotechnology from our laboratory

Arun Chattopadhyay

2008-01-01

210

LAMELLAR MAGNETISM ASSOCIATED WITH NANOSCALE EXSOLUTION  

E-print Network

LAMELLAR MAGNETISM ASSOCIATED WITH NANOSCALE EXSOLUTION IN THE ILMENITE-HEMATITE SOLID SOLUTION-hematite (FeTiO3-Fe2O3) solid solution is one of the most important magnetic phases in nature. Unusual magnetic, magnetic ordering, and exsolution. This presentation describes how this interaction leads to the phenomenon

Dunin-Borkowski, Rafal E.

211

Benchtop Nanoscale Patterning Using Soft Lithography  

ERIC Educational Resources Information Center

This paper outlines several benchtop nanoscale patterning experiments that can be incorporated into undergraduate laboratories or advanced high school chemistry curricula. The experiments, supplemented by an online video lab manual, are based on soft lithographic techniques such as replica molding, micro-molding in capillaries, and micro-contact…

Meenakshi, Viswanathan; Babayan, Yelizaveta; Odom, Teri W.

2007-01-01

212

Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens  

NASA Astrophysics Data System (ADS)

Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

2012-11-01

213

Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens  

SciTech Connect

Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R. [Core Systems, 1050 Kifer Road Sunnyvale, CA 94086 (United States); FI Silicon, 1050 Kifer Road Sunnyvale, CA 94086 (United States); Core Systems, 1050 Kifer Road Sunnyvale, CA 94086 (United States)

2012-11-06

214

C. elegans bicd-1, homolog of the Drosophila dynein accessory factor Bicaudal D, regulates the branching of PVD sensory neuron dendrites  

PubMed Central

The establishment of cell type-specific dendritic arborization patterns is a key phase in the assembly of neuronal circuitry that facilitates the integration and processing of synaptic and sensory input. Although studies in Drosophila and vertebrate systems have identified a variety of factors that regulate dendrite branch formation, the molecular mechanisms that control this process remain poorly defined. Here, we introduce the use of the Caenorhabditis elegans PVD neurons, a pair of putative nociceptors that elaborate complex dendritic arbors, as a tractable model for conducting high-throughput RNAi screens aimed at identifying key regulators of dendritic branch formation. By carrying out two separate RNAi screens, a small-scale candidate-based screen and a large-scale screen of the ?3000 genes on chromosome IV, we retrieved 11 genes that either promote or suppress the formation of PVD-associated dendrites. We present a detailed functional characterization of one of the genes, bicd-1, which encodes a microtubule-associated protein previously shown to modulate the transport of mRNAs and organelles in a variety of organisms. Specifically, we describe a novel role for bicd-1 in regulating dendrite branch formation and show that bicd-1 is likely to be expressed, and primarily required, in PVD neurons to control dendritic branching. We also present evidence that bicd-1 operates in a conserved pathway with dhc-1 and unc-116, components of the dynein minus-end-directed and kinesin-1 plus-end-directed microtubule-based motor complexes, respectively, and interacts genetically with the repulsive guidance receptor unc-5. PMID:21205795

Aguirre-Chen, Cristina; Bülow, Hannes E.; Kaprielian, Zaven

2011-01-01

215

Iwasawa effects in multilayer optics.  

PubMed

There are many two-by-two matrices in layer optics. It is shown that they can be formulated in terms of a three-parameter group whose algebraic property is the same as the group of Lorentz transformations in a space with two spacelike and one timelike dimensions, or the Sp(2) group which is a standard theoretical tool in optics. Among the interesting mathematical properties of this group, the Iwasawa decomposition drastically simplifies the matrix algebra under certain conditions, and leads to a concise expression for the S matrix for transmitted and reflected waves. It is shown that the Iwasawa effect can be observed in multilayer optics, and a sample calculation of the S matrix is given. PMID:11497725

Georgieva, E; Kim, Y S

2001-08-01

216

Performance prediction of multilayer insulation  

NASA Astrophysics Data System (ADS)

Multilayer insulation (MLI), using alternate layers of shield and spacer material, is the most effective insulation developed so far for cryogenic applications. The effective thermal conductivity of MLI is a function of various parameters, such as shield and spacer materials, number of layers and layer density, contact pressure, vacuum maintained and interstitial pressure. This paper presents an analysis involving fabric spacer material. The model considers the heat transfer by various modes such as solid conduction, conduction through contact surfaces, radiation through the exposed area between adjacent shields and radiation through the fibrous spacer. Gas conduction has also been considered, taking into account the estimated interstitial pressure. Results are presented for the radiation mode alone, as well as for radiation, conduction and gas conduction considered collectively.

Bapat, S. L.; Narayankhedkar, K. G.; Lukose, T. P.

1990-08-01

217

Preface: Friction at the nanoscale  

NASA Astrophysics Data System (ADS)

Interfacial friction is one of the oldest problems in physics and chemistry, and certainly one of the most important from a practical point of view. Everyday operations on a broad range of scales, from nanometer and up, depend upon the smooth and satisfactory functioning of countless tribological systems. Friction imposes serious constraints and limitations on the performance and lifetime of micro-machines and, undoubtedly, will impose even more severe constraints on the emerging technology of nano-machines. Standard lubrication techniques used for large objects are expected to be less effective in the nano-world. Novel methods for control and manipulation are therefore needed. What has been missing is a molecular level understanding of processes occurring between and close to interacting surfaces to help understand, and later manipulate friction. Friction is intimately related to both adhesion and wear, and all three require an understanding of highly non-equilibrium processes occurring at the molecular level to determine what happens at the macroscopic level. Due to its practical importance and the relevance to basic scientific questions there has been major increase in activity in the study of interfacial friction on the microscopic level during the last decade. Intriguing structural and dynamical features have been observed experimentally. These observations have motivated theoretical efforts, both numerical and analytical. This special issue focusses primarily on discussion of microscopic mechanisms of friction and adhesion at the nanoscale level. The contributions cover many important aspects of frictional behaviour, including the origin of stick-slip motion, the dependence of measured forces on the material properties, effects of thermal fluctuations, surface roughness and instabilities in boundary lubricants on both static and kinetic friction. An important problem that has been raised in this issue, and which has still to be resolved, concerns the possibility of controlling frictional response. The ability to control and manipulate frictional forces is extremely important for a variety of applications. These include magnetic storage and recording systems, miniature motors, and more. This special issue aims to provide an overview of current theoretical and experimental works on nanotribology and possible applications. In selecting the papers we have tried to maintain a balance between new results and review-like aspects, so that the present issue is self-contained and, we hope, readily accessible to non-specialists in the field. We believe that the particular appeal of this collection of papers also lies in the fusion of both experiment and theory, thus providing the connection to reality of the sometimes demanding, mathematically inclined contributions. Profound thanks go to all our colleagues and friends who have contributed to this special issue. Each has made an effort not only to present recent results in a clear and lucid way, but also to provide an introductory review that helps the reader to understand the different topics.

Fusc, Claudio; Smith, Roger; Urbakh, Michael; Vanossi, Andrea

2008-09-01

218

Schwinger pair creation in multilayer graphene  

E-print Network

The low energy effective field model for the multilayer graphene (at ABC stacking) in external Electric field is considered. The Schwinger pair creation rate and the vacuum persistence probability are calculated using the semi - classical approach.

M. A. Zubkov

2012-03-31

219

Review of the multilayer coating model  

E-print Network

The recent theoretical study on the multilayer-coating model published in Applied Physics Letters [1] is reviewed. Magnetic-field attenuation behavior in a multilayer coating model is different from a semi-infinite superconductor and a superconducting thin film. This difference causes that of the vortex-penetration field at which the Bean-Livingston surface barrier disappears. A material with smaller penetration depth, such as a pure Nb, is preferable as the substrate for pushing up the vortex-penetration field of the superconductor layer. The field limit of the whole structure of the multilayer coating model is limited not only by the vortex-penetration field of the superconductor layer, but also by that of the substrate. Appropriate thicknesses of superconductor and insulator layers can be extracted from contour plots of the field limit of the multilayer coating model given in Ref.[1].

Kubo, Takayuki; Saeki, Takayuki

2014-01-01

220

Biological applications of weal polyelectrolyte multilayers  

E-print Network

This thesis research focused on biological applications of ultra-thin weak polyelectrolyte multilayers with specific emphasis on cell patterning, drug delivery, and antibacterial coatings. All of these very different ...

Berg, Michael C., Ph. D. Massachusetts Institute of Technology

2005-01-01

221

Subwavelength Multilayer Dielectrics: Ultrasensitive Transmission and Breakdown of Effective-Medium Theory  

NASA Astrophysics Data System (ADS)

We show that a purely dielectric structure made of alternating layers of deep subwavelength thicknesses exhibits novel transmission effects which completely contradict conventional effective medium theories exactly in the regime in which those theories are commonly used. We study waves incident at the vicinity of the effective medium's critical angle for total internal reflection and show that the transmission through the multilayer structure depends strongly on nanoscale variations even at layer thicknesses smaller than ? /50 . In such deep subwavelength structures, we demonstrate dramatic changes in the transmission for variations in properties such as periodicity, order of the layers, and their parity. In addition to its conceptual importance, such sensitivity has important potential applications in sensing and switching.

Herzig Sheinfux, Hanan; Kaminer, Ido; Plotnik, Yonatan; Bartal, Guy; Segev, Mordechai

2014-12-01

222

Subwavelength multilayer dielectrics: ultrasensitive transmission and breakdown of effective-medium theory.  

PubMed

We show that a purely dielectric structure made of alternating layers of deep subwavelength thicknesses exhibits novel transmission effects which completely contradict conventional effective medium theories exactly in the regime in which those theories are commonly used. We study waves incident at the vicinity of the effective medium's critical angle for total internal reflection and show that the transmission through the multilayer structure depends strongly on nanoscale variations even at layer thicknesses smaller than ?/50. In such deep subwavelength structures, we demonstrate dramatic changes in the transmission for variations in properties such as periodicity, order of the layers, and their parity. In addition to its conceptual importance, such sensitivity has important potential applications in sensing and switching. PMID:25541773

Herzig Sheinfux, Hanan; Kaminer, Ido; Plotnik, Yonatan; Bartal, Guy; Segev, Mordechai

2014-12-12

223

Capability of etched multilayer EUV mask fabrication  

NASA Astrophysics Data System (ADS)

Recently, development of next generation extremely ultraviolet lithography (EUVL) equipment with high-NA (Numerical Aperture) optics for less than hp10nm node is accelerated. Increasing magnification of projection optics or mask size using conventional mask structure has been studied, but these methods make lithography cost high because of low through put and preparing new large mask infrastructures. To avoid these issues, etched multilayer EUV mask has been proposed. As a result of improvement of binary etched multilayer mask process, hp40nm line and space pattern on mask (hp10nm on wafer using 4x optics) has been demonstrated. However, mask patterns are easily collapsed by wet cleaning process due to their low durability caused by high aspect ratio. We propose reducing the number of multilayer pairs from 40 to 20 in order to increase durability against multilayer pattern collapse. With 20pair multilayer blank, durable minimum feature size of isolated line is extended from 80nm to 56nm. CD uniformity and linearity of 20pair etched multilayer pattern are catching up EUV mask requirement of 2014.

Takai, Kosuke; Murano, Koji; Kamo, Takashi; Morikawa, Yasutaka; Hayashi, Naoya

2014-09-01

224

MoRu/Be multilayers for extreme ultraviolet applications  

DOEpatents

High reflectance, low intrinsic roughness and low stress multilayer systems for extreme ultraviolet (EUV) lithography comprise amorphous layers MoRu and crystalline Be layers. Reflectance greater than 70% has been demonstrated for MoRu/Be multilayers with 50 bilayer pairs. Optical throughput of MoRu/Be multilayers can be 30-40% higher than that of Mo/Be multilayer coatings. The throughput can be improved using a diffusion barrier to make sharper interfaces. A capping layer on the top surface of the multilayer improves the long-term reflectance and EUV radiation stability of the multilayer by forming a very thin native oxide that is water resistant.

Bajt, Sasa C. (Livermore, CA); Wall, Mark A. (Stockton, CA)

2001-01-01

225

Nanoscale plasmonic memristor with optical readout functionality.  

PubMed

We experimentally demonstrate for the first time a nanoscale resistive random access memory (RRAM) electronic device integrated with a plasmonic waveguide providing the functionality of optical readout. The device fabrication is based on silicon on insulator CMOS compatible approach of local oxidation of silicon, which enables the realization of RRAM and low optical loss channel photonic waveguide at the same fabrication step. This plasmonic device operates at telecom wavelength of 1.55 ?m and can be used to optically read the logic state of a memory by measuring two distinct levels of optical transmission. The experimental characterization of the device shows optical bistable behavior between these levels of transmission in addition to well-defined hysteresis. We attribute the changes in the optical transmission to the creation of a nanoscale absorbing and scattering metallic filament in the amorphous silicon layer, where the plasmonic mode resides. PMID:24256313

Emboras, Alexandros; Goykhman, Ilya; Desiatov, Boris; Mazurski, Noa; Stern, Liron; Shappir, Joseph; Levy, Uriel

2013-01-01

226

Phase transitions in nanoscale ferroelectric structures.  

SciTech Connect

Over decades of effort, investigations of the intrinsic phase transition behavior of nanoscale ferroelectric structures have been greatly complicated by materials processing variations and by the common and uncontrolled occurrence of spacecharge, which interacts directly with the polarization and can obscure fundamental behavior. These challenges have largely been overcome, and great progress in understanding the details of this class of phase transitions has been made, largely based on advances in the growth of high-quality, epitaxial ferroelectric films and in the theory and simulation of ferroelectricity. Here we will discuss recent progress in understanding the ferroelectric phase transition in a particular class of model systems: nanoscale perovskite thin-film heterostructures. The outlook for ferroelectric technology based on these results is promising, and extensions to laterally confined nanostructures will be described.

Streiffer, S. K.; Fong, D. D. (Center for Nanoscale Materials); ( MSD)

2009-01-01

227

Nanoscale Thermometry Using Point Contact Thermocouples  

SciTech Connect

Probing temperature fields with nanometer resolution is critical to understanding nanoscale thermal transport as well as dissipation in nanoscale devices. Here, we demonstrate an atomic force microscope (AFM)-based technique capable of mapping temperature fields in metallic films with ?10 mK temperature resolution and <100 nm spatial resolution. A platinum-coated AFM cantilever placed in soft mechanical contact with a metallic (gold) surface is used to sequentially create point contact thermocouples on a grid. The local temperature at each point contact is obtained by measuring the thermoelectric voltage of the platinum?gold point contact and relating it to the local temperature. These results demonstrate a direct measurement of the temperature field of a metallic surface without using specially fabricated scanning temperature-probes.

Sadat, Seid; Tan, Aaron; Chua, Yi Jie; Reddy, Pramod

2010-01-01

228

Silicon epitaxy in nanoscale for photovoltaic applications  

NASA Astrophysics Data System (ADS)

Nanostructures provide novel opportunities of studying epitaxy in nano/mesoscale and on nonplanar substrates. Epitaxial growth of silicon (Si) on the surfaces of Si nanowires along radial direction is a promising way to prepare radial p-(i)-n junction in nanoscale for optoelectronic devices. Comprehensive studies of Si radial epitaxy in micro/nanoscale reveal that morphological evolution and size-dependent radial shell growth rate for undoped and doped Si radial shells. Single crystalline Si radial p-i-n junction wire arrays were utilized to fabricate photovoltaic (PV) devices. The PV devices exhibited the photoconversion efficiency of 10%, the short-circuit current density of 39 mA/cm2, and the open-circuit voltage of 0.52 V, respectively.

Yoo, Jinkyoung; Nguyen, Binh-Minh; Dayeh, Shadi A.; Schuele, Paul; Evans, David; Picraux, S. T.

2014-09-01

229

Trapping atoms using nanoscale quantum vacuum forces  

PubMed Central

Quantum vacuum forces dictate the interaction between individual atoms and dielectric surfaces at nanoscale distances. For example, their large strengths typically overwhelm externally applied forces, which makes it challenging to controllably interface cold atoms with nearby nanophotonic systems. Here we theoretically show that it is possible to tailor the vacuum forces themselves to provide strong trapping potentials. Our proposed trapping scheme takes advantage of the attractive ground-state potential and adiabatic dressing with an excited state whose potential is engineered to be resonantly enhanced and repulsive. This procedure yields a strong metastable trap, with the fraction of excited-state population scaling inversely with the quality factor of the resonance of the dielectric structure. We analyse realistic limitations to the trap lifetime and discuss possible applications that might emerge from the large trap depths and nanoscale confinement. PMID:25008119

Chang, D. E.; Sinha, K.; Taylor, J. M.; Kimble, H. J.

2014-01-01

230

Nanoscale thermometry using point contact thermocouples.  

PubMed

Probing temperature fields with nanometer resolution is critical to understanding nanoscale thermal transport as well as dissipation in nanoscale devices. Here, we demonstrate an atomic force microscope (AFM)-based technique capable of mapping temperature fields in metallic films with approximately 10 mK temperature resolution and <100 nm spatial resolution. A platinum-coated AFM cantilever placed in soft mechanical contact with a metallic (gold) surface is used to sequentially create point contact thermocouples on a grid. The local temperature at each point contact is obtained by measuring the thermoelectric voltage of the platinum-gold point contact and relating it to the local temperature. These results demonstrate a direct measurement of the temperature field of a metallic surface without using specially fabricated scanning temperature-probes. PMID:20550098

Sadat, Seid; Tan, Aaron; Chua, Yi Jie; Reddy, Pramod

2010-07-14

231

Programmed assembly of nanoscale structures using peptoids.  

SciTech Connect

Sequence-specific polymers are the basis of the most promising approaches to bottom-up programmed assembly of nanoscale materials. Examples include artificial peptides and nucleic acids. Another class is oligo(N-functional glycine)s, also known as peptoids, which permit greater sidegroup diversity and conformational control, and can be easier to synthesize and purify. We have developed a set of peptoids that can be used to make inorganic nanoparticles more compatible with biological sequence-specific polymers so that they can be incorporated into nucleic acid or other biologically based nanostructures. Peptoids offer degrees of modularity, versatility, and predictability that equal or exceed other sequence-specific polymers, allowing for rational design of oligomers for a specific purpose. This degree of control will be essential to the development of arbitrarily designed nanoscale structures.

Ren, Jianhua (University of the Pacific, Stockton, CA); Russell, Scott (California State University, Stanislaus, Turlock, CA); Morishetti, Kiran (University of the Pacific, Stockton, CA); Robinson, David B.; Zuckermann, Ronald N. (Lawrence Berkeley National Laboratory, Berkeley, CA); Buffleben, George M.; Hjelm, Rex P. (Los Alamos National Laboratory, Los Alamos, NM); Kent, Michael Stuart (Sandia National Laboratories, Albuquerque, NM)

2011-02-01

232

Nanoscale Thermal Mapping of VO2  

NASA Astrophysics Data System (ADS)

We present a method for nanoscale thermal imaging of insulating thin films. We image the local temperature of the metal-insulator transition in a VO2 film, and investigate the role of Joule heating in two-terminal geometry. By sweeping the voltage applied to a conducting atomic force microscope tip in contact mode, we locally trigger and detect the transition to the metallic phase. By fitting the Poole-Frenkel conduction regime immediately preceding the transition, we extract the local temperature. Finally, we find grains displaying two electronic transitions, consistent with a locally stable intermediate insulating phase.[4pt] We acknowledge financial support from Harvard's Nanoscale Science and Engineering Center, funded by NSF grant PHY 01-17795 and the Sloan Fellowship. Adam Pivonka acknowledges the support of the New York Community Trust--George Merck Fund. Magdalena Huefner acknowledges the support of the Deutsche Forschungsgemeinschaft (HU 1960/11).

Pivonka, Adam; Huefner, Magdalena; Ko, Changhyun; Frenzel, Alex; O'Connor, Kevin; Ramanathan, Shriram; Hudson, Eric; Hoffman, Jennifer

2013-03-01

233

Light-driven nanoscale plasmonic motors  

NASA Astrophysics Data System (ADS)

When Sir William Crookes developed a four-vaned radiometer, also known as the light-mill, in 1873, it was believed that this device confirmed the existence of linear momentum carried by photons, as predicted by Maxwell's equations. Although Reynolds later proved that the torque on the radiometer was caused by thermal transpiration, researchers continued to search for ways to take advantage of the momentum of photons and to use it for generating rotational forces. The ability to provide rotational force at the nanoscale could open up a range of applications in physics, biology and chemistry, including DNA unfolding and sequencing and nanoelectromechanical systems. Here, we demonstrate a nanoscale plasmonic structure that can, when illuminated with linearly polarized light, generate a rotational force that is capable of rotating a silica microdisk that is 4,000 times larger in volume. Furthermore, we can control the rotation velocity and direction by varying the wavelength of the incident light to excite different plasmonic modes.

Liu, Ming; Zentgraf, Thomas; Liu, Yongmin; Bartal, Guy; Zhang, Xiang

2010-08-01

234

Collagen-based fibrillar multilayer films cross-linked by a natural agent.  

PubMed

Surface functionalization plays an important role in the design of biomedical implants, especially when layer forming cells, such as endothelial or epithelial cells, are needed. In this study, we define a novel nanoscale surface coating composed of collagen/alginate polyelectrolyte multilayers and cross-linked for stability with genipin. This buildup follows an exponential growth regime versus the number of deposition cycles with a distinct nanofibrillar structure that is not damaged by the cross-linking step. Stability and cell compatibility of the cross-linked coatings were studied with human umbilical vein endothelial cells. The surface coating can be covered by a monolayer of vascular endothelial cells within 5 days. Genipin cross-linking renders the surface more suitable for cell attachment and proliferation compared to glutaraldehyde (more conventional cross-linker) cross-linked surfaces, where cell clumps in dispersed areas were observed. In summary, it is possible with the defined system to build fibrillar structures with a nanoscale control of film thickness, which would be useful for in vivo applications such as inner lining of lumens for vascular and tracheal implants. PMID:22662909

Chaubaroux, Christophe; Vrana, Engin; Debry, Christian; Schaaf, Pierre; Senger, Bernard; Voegel, Jean-Claude; Haikel, Youssef; Ringwald, Christian; Hemmerlé, Joseph; Lavalle, Philippe; Boulmedais, Fouzia

2012-07-01

235

Nanoscale Science, Engineering and Technology Research Directions  

SciTech Connect

This report describes important future research directions in nanoscale science, engineering and technology. It was prepared in connection with an anticipated national research initiative on nanotechnology for the twenty-first century. The research directions described are not expected to be inclusive but illustrate the wide range of research opportunities and challenges that could be undertaken through the national laboratories and their major national scientific user facilities with the support of universities and industry.

Lowndes, D. H.; Alivisatos, A. P.; Alper, M.; Averback, R. S.; Jacob Barhen, J.; Eastman, J. A.; Imre, D.; Lowndes, D. H.; McNulty, I.; Michalske, T. A.; Ho, K-M; Nozik, A. J.; Russell, T. P.; Valentin, R. A.; Welch, D. O.; Barhen, J.; Agnew, S. R.; Bellon, P.; Blair, J.; Boatner, L. A.; Braiman, Y.; Budai, J. D.; Crabtree, G. W.; Feldman, L. C.; Flynn, C. P.; Geohegan, D. B.; George, E. P.; Greenbaum, E.; Grigoropoulos, C.; Haynes, T. E.; Heberlein, J.; Hichman, J.; Holland, O. W.; Honda, S.; Horton, J. A.; Hu, M. Z.-C.; Jesson, D. E.; Joy, D. C.; Krauss, A.; Kwok, W.-K.; Larson, B. C.; Larson, D. J.; Likharev, K.; Liu, C. T.; Majumdar, A.; Maziasz, P. J.; Meldrum, A.; Miller, J. C.; Modine, F. A.; Pennycook, S. J.; Pharr, G. M.; Phillpot, S.; Price, D. L.; Protopopescu, V.; Poker, D. B.; Pui, D.; Ramsey, J. M.; Rao, N.; Reichl, L.; Roberto, J.; Saboungi, M-L; Simpson, M.; Strieffer, S.; Thundat, T.; Wambsganss, M.; Wendleken, J.; White, C. W.; Wilemski, G.; Withrow, S. P.; Wolf, D.; Zhu, J. H.; Zuhr, R. A.; Zunger, A.; Lowe, S.

1999-01-01

236

Nanoscale thermal transport. II. 2003–2012  

SciTech Connect

A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ?1?nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal analysis using proximal probes has achieved spatial resolution of 10?nm, temperature precision of 50 mK, sensitivity to heat flows of 10 pW, and the capability for thermal analysis of sub-femtogram samples.

Cahill, David G., E-mail: d-cahill@illinois.edu; Braun, Paul V. [Department of Materials Science and Engineering and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Chen, Gang [Department of Mechanical Engineering, MIT, Cambridge, Massachusetts 02139 (United States); Clarke, David R. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Fan, Shanhui [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Goodson, Kenneth E. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Keblinski, Pawel [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); King, William P. [Department of Mechanical Sciences and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Mahan, Gerald D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States); Majumdar, Arun [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Maris, Humphrey J. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Phillpot, Simon R. [Department of Materials Science and Engineering, University of Florida, Gainseville, Florida 32611 (United States); Pop, Eric [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Shi, Li [Department of Mechanical Engineering, University of Texas, Autin, Texas 78712 (United States)

2014-03-15

237

Nanoscale molecularly imprinted polymers and method thereof  

DOEpatents

Nanoscale molecularly imprinted polymers (MIP) having polymer features wherein the size, shape and position are predetermined can be fabricated using an xy piezo stage mounted on an inverted microscope and a laser. Using an AMF controller, a solution containing polymer precursors and a photo initiator are positioned on the xy piezo and hit with a laser beam. The thickness of the polymeric features can be varied from a few nanometers to over a micron.

Hart, Bradley R. (Brentwood, CA); Talley, Chad E. (Brentwood, CA)

2008-06-10

238

Nanoscale thermal transport. II. 2003-2012  

NASA Astrophysics Data System (ADS)

A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ˜1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal analysis using proximal probes has achieved spatial resolution of 10 nm, temperature precision of 50 mK, sensitivity to heat flows of 10 pW, and the capability for thermal analysis of sub-femtogram samples.

Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

2014-03-01

239

Biomolecules–Nanoparticles: Interaction in Nanoscale  

Microsoft Academic Search

\\u000a Even though the production of nanoparticles of silver and gold dates back many centuries, characterization and manipulation\\u000a at nanoscale has initiated a new era for nanotechnology. Spreading its wings beyond physics and materials science, its scope\\u000a of application in molecular biology, biochemistry, and medicine is only recently being appreciated. This necessitated a need\\u000a for the interaction between nanoparticles and biomolecules.

N. Vigneshwaran; Prateek Jain

240

Center for Nanoscale Science and Technology  

NSDL National Science Digital Library

The Center for Nanoscale Science and Technology consists of a Research Program and the Nanofab, a shared-use facility providing economical access to state-of-the-art nanofabrication and nano-measurement tools. The CNST Nanofab is now available for use by non-NIST users. See "What we do", to the left, for a description of CNST and its Research Program as well as the CNST Nanofab and its use policies.

2010-05-18

241

Module Four - The Uniqueness of the Nanoscale  

NSDL National Science Digital Library

This module covers the unique attributes of the nano-scale and some examples of these unique attributes, including small size, high surface to volume ratio, surface forces in relation to bulk forces, quantum mechanical effects, and wave properties of light. This module is from the Nanotechnology Applications and Career Knowledge (NACK), a National ATE Center. This site requires a free log-in to access.

242

Multilayer Piezoelectric Stack Actuator Characterization  

NASA Technical Reports Server (NTRS)

Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

2008-01-01

243

Bumpy, Sticky, and Shaky: Nanoscale Science and the Curriculum  

NSDL National Science Digital Library

Nanoscience, or the study of the world at the size of a billionth of a meter, has the potential to help students see how all of the sciences are related. Behavior of materials at the nanoscale differs from materials at the macroscale. This article introduces three nanoscale properties and how they relate to various science domains. Three activities following an adapted learning cycle model are suggested for student exploration of three properties of the nanoscale: bumpy, sticky, and shaky.

Taylor, Amy; Jones, Gail; Pearl, Thomas P.

2008-03-01

244

Treatment of chlorinated organic contaminants with nanoscale bimetallic particles  

Microsoft Academic Search

Nanoscale bimetallic particles (Pd\\/Fe, Pd\\/Zn, Pt\\/Fe, Ni\\/Fe) have been synthesized in the laboratory for treatment of chlorinated organic pollutants. Specific surface areas of the nanoscale particles are tens of times larger than those of commercially available microscale metal particles. Rapid and complete dechlorination of several chlorinated organic solvents and chlorinated aromatic compounds was achieved by using the nanoscale bimetallic particles.

Wei-xian Zhang; Chuan-Bao Wang; Hsing-Lung Lien

1998-01-01

245

Combined single cell AFM manipulation and TIRFM for probing the molecular stability of multilayer fibrinogen matrices  

PubMed Central

Adsorption of fibrinogen on various surfaces produces a nanoscale multilayer matrix, which strongly reduces the adhesion of platelets and leukocytes with implications for hemostasis and blood compatibility of biomaterials. The nonadhesive properties of fibrinogen matrices are based on their extensibility, ensuing the inability to transduce strong mechanical forces via cellular integrins and resulting in weak intracellular signaling. In addition, reduced cell adhesion may arise from the weaker associations between fibrinogen molecules in the superficial layers of the matrix. Such reduced stability would allow integrins to pull fibrinogen molecules out of the matrix with comparable or smaller forces than required to break integrin–fibrinogen bonds. To examine this possibility, we developed a method based on the combination of total internal reflection fluorescence microscopy, single cell manipulation with an atomic force microscope and microcontact printing to study the transfer of fibrinogen molecules out of a matrix onto cells. We calculated the average fluorescence intensities per pixel for wild-type HEK 293 (HEK WT) and HEK 293 cells expressing leukocyte integrin Mac-1 (HEK Mac-1) before and after contact with multilayered matrices of fluorescently labeled fibrinogen. For contact times of 500 s, HEK Mac-1 cells show a median increase of 57% of the fluorescence intensity compared to 6% for HEKWT cells. The results suggest that the integrin Mac-1-fibrinogen interactions are stronger than the intermolecular fibrinogen interactions in the superficial layer of the matrix. The low mechanical stability of the multilayer fibrinogen surface may contribute to the reduced cell adhesive properties of fibrinogen-coated substrates. We anticipate that the described method can be applied to various cell types to examine their integrin-mediated adhesion to the extracellular matrices with a variable protein composition. PMID:24239757

Christenson, W.; Yermolenko, I.; Plochberger, B.; Camacho-Alanis, F.; Ros, A.; Ugarova, T.P.; Ros, R.

2014-01-01

246

78 FR 30329 - Multilayered Wood Flooring from China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1179 (Final) (Remand)] Multilayered Wood Flooring from China AGENCY: United States...731-TA-1179 (Final) concerning multilayered wood flooring (``MLWF'') from China...Floors, Inc.; BR Custom Surface; Real Wood Floors, LLC; Galleher Corp.; and...

2013-05-22

247

Tailorable stimulated Brillouin scattering in nanoscale silicon waveguides  

E-print Network

Nanoscale modal confinement is known to radically enhance the effect of intrinsic Kerr and Raman nonlinearities within nanophotonic silicon waveguides. By contrast, stimulated Brillouin-scattering nonlinearities, which ...

Shin, Heedeuk

248

Novel materials, computational spectroscopy, and multiscale simulation in nanoscale photovoltaics  

E-print Network

Photovoltaic (PV) solar cells convert solar energy to electricity using combinations of semiconducting sunlight absorbers and metallic materials as electrical contacts. Novel nanoscale materials introduce new paradigms for ...

Bernardi, Marco, Ph. D. Massachusetts Institute of Technology

2013-01-01

249

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto  

DOEpatents

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

2014-07-22

250

Layer-by-layer assembly of {nanoclay-(sol-gel oxide)}n and {nanoclay-(oxide nanoparticle)}n multilayers: Synthesis and growth mechanisms  

NASA Astrophysics Data System (ADS)

Two new classes of all-inorganic nanostructured multilayers, {MMT x-(sol-gel oxide)}n and {MMTx-(oxide nanoparticle)} n, have been successfully synthesized for the first time. They were made by adapting a layer-by-layer (LbL) assembly method initially developed to synthesize polyelectrolyte-based multilayers. In most previous studies, this electrostatic-assisted LbL assembly method used polyelectrolytes/polymers as the "structural glue" to prepare multilayers. The synthesis of {MMTx-(sol-gel ZrO2)}n multilayers demonstrates for the first time the feasibility of making sol-gel oxide "glued" all-inorganic multilayers, thereby introducing an innovative nanoscale fabrication concept. The synthesis of {MMTx-(oxide nanoparticle)}n multilayers further illustrates the versatility of LbL assembly technique by achieving a second new type of all-inorganic multilayers with a novel "plate-ball" architecture. The feasibility of synthesizing other types of multilayer structures, including {MMTx-(ionic liquid)}n, {(carbon nanotube)-(sol-gel ZrO2)}n, and {polymer-(sol-gel ZrO2)} n, were also explored. Systematical investigations of the growth kinetics of {MMTx-(sol-gel ZrO2)}n multilayers reveal unique underlying mechanisms for electrostatic-assisted growth of sol-gel films and LbL assembly. The growth of the MMT and sol-gel ZrO2 layers is strongly coupled. For fresh aqueous ZrO2 precursors, the growth rates of sol-gel ZrO2 layers on MMT surfaces as functions of time and precursor concentration do not follow the standard mass transfer or interfacial reaction controlled kinetic models. Furthermore, the growth of the sol-gel oxide layers on MMT surfaces is self-limited to a maximum thickness of ˜50-60 nm. These observations suggest a surface-mediated growth of sol-gel 'oxide layers on MMT surfaces, one that is likely controlled by electrostatic interactions. These new findings significantly advance the general understanding of the LbL electrostatic assembly process. For the aged precursors, the growth mechanism differs; the growth of sol-gel oxide layers is controlled by hydrodynamics and follows the Landau-Levich model. For as-deposited multilayers, isothermal annealing at ˜400°C dehydrates them and removes the residue acetate groups without damaging the MMT nanoplatelets and the ordered layer structures. Nanomechanical measurements show that the elastic modulus of the multilayers can be intentionally tuned by changing the multilayer design and that significant porosity is present in the multilayers even after annealing. In addition, free-standing multilayers are successfully made via using sacrificial substrates, and the newly developed methodology for {MMTx-(sol-gel oxide)} n can be extended, using other metal oxides, e.g., SnO2, as the inorganic "glue." Potential applications of these new nanostructured multilayers are discussed.

Chen, Hao

251

Spin wave resonance and relaxation in microwave magnetic multilayer structures and devices  

NASA Astrophysics Data System (ADS)

The continuous and increasing demand for higher frequency magnetic microwave structures triggered a tremendous development in the field of magnetization dynamics over the past decade. In order to develop smaller and faster devices, more efforts are required to achieve a better understanding of the complex magnetization precessional dynamics, the magnetization anisotropy, and the sources of spin scattering at the nanoscale. This thesis presents measurements of magnetic precession and relaxation dynamics in multilayer ferromagnetic films of CoFe/PtMn/CoFe in both frequency and time domain. First, we conducted the ferromagnetic resonance (FMR) measurements for samples with the ferromagnetic CoFe layer thicknesses varying from 10 A to 500 A. The magnetic anisotropic parameters were determined by rotating the field aligned axis with respect to the spectral field in the configurations of both in-plane and out-of-plane. Moreover, we identified a high-order standing spin wave in our spectra and found a "critical angle" in the multilayer samples. We included an effective surface anisotropy field to describe our results. This allows us to determine the exchange interaction stiffness in the CoFe layers. Next, we performed pump-probe Magneto-Optical Kerr Effect experiments in the multilayer films. Three precession modes were observed in the Voigt geometry. The modes are assigned to the exchange-dominated spin wave excitations and the non-homogeneous dipole mode. We developed a comprehensive model of the magnetic eigenmodes and their coupling to light to gain accurate values of the exchange, bulk and surface anisotropy constants. The results are consistent with those from the FMR measurements. Finally, the measured resonance linewidths of CoFe/PtMn/CoFe films were analyzed by the thickness dependence of the CoFe layers. We discussed the contribution of the Gilbert damping, two magnon scattering, as well as surface and interface to the FMR linewidth and concluded the two magnon scattering plays the most important role in FMR linewidth broadening and reaffirmed the significance of surface effects for spin wave damping in these samples. The results of this thesis will lead to new insights into important magnetic properties of ferromagnetic films and therefore provide essential knowledge for optimizing the GHz response of the nanoscale magnetic elements and devices.

Wu, Cheng

252

Cutting performance of multicomponent and multilayer coatings on cemented carbides and cermets for interrupted cut machining  

Microsoft Academic Search

Service lifetime of PVD-coated cemented carbide or cermet tools is several times higher than that of uncoated equivalents, with associated increase in production reliability and quality. The performance characteristic of coated tools is determined both by the quality of the substrate material and by the composition and structure of the coating.Under the substrate relieving effects of PVD coatings, ultra-tough WC-Co

O. Knotek; F. Löffler; G. Krämer

1996-01-01

253

Maximum screening fields of superconducting multilayer structures  

E-print Network

It is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields $H_s$ of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness $\\sim 0.1\\; \\mu$m at the Nb surface could increase $H_s\\simeq 240$ mT of a clean Nb up to $H_s\\simeq 290$ mT. Optimized multilayers of Nb$_3$Sn, NbN, some of the iron pnictides, or alloyed Nb deposited onto the surface of the Nb resonator cavities could potentially double the rf breakdown field, pushing the peak accelerating electric fields above 100 MV/m while protecting the cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.

Gurevich, Alex

2015-01-01

254

Maximum screening fields of superconducting multilayer structures  

NASA Astrophysics Data System (ADS)

It is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields Hs of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness ˜0.1 ?m at the Nb surface could increase Hs ? 240 mT of a clean Nb up to Hs ? 290 mT. Optimized multilayers of Nb3Sn, NbN, some of the iron pnictides, or alloyed Nb deposited onto the surface of the Nb resonator cavities could potentially double the rf breakdown field, pushing the peak accelerating electric fields above 100 MV/m while protecting the cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.

Gurevich, Alex

2015-01-01

255

Imaging Schwarzschild multilayer X-ray microscope  

NASA Technical Reports Server (NTRS)

We have designed, analyzed, fabricated, and tested Schwarzschild multilayer X-ray microscopes. These instruments use flow-polished Zerodur mirror substrates which have been coated with multilayers optimized for maximum reflectivity at normal incidence at 135 A. They are being developed as prototypes for the Water Window Imaging X-Ray Microscope. Ultrasmooth mirror sets of hemlite grade sapphire have been fabricated and they are now being coated with multilayers to reflect soft X-rays at 38 A, within the biologically important 'water window'. In this paper, we discuss the fabrication of the microscope optics and structural components as well as the mounting of the optics and assembly of the microscopes. We also describe the optical alignment, interferometric and visible light testing of the microscopes, present interferometrically measured performance data, and provide the first results of optical imaging tests.

Hoover, Richard B.; Baker, Phillip C.; Shealy, David L.; Core, David B.; Walker, Arthur B. C., Jr.; Barbee, Troy W., Jr.; Kerstetter, Ted

1993-01-01

256

Investigation of multilayer magnetic domain lattice file  

NASA Technical Reports Server (NTRS)

The feasibility of the self structured multilayered bubble domain memory as a mass memory medium for satellite applications is examined. Theoretical considerations of multilayer bubble supporting materials are presented, in addition to the experimental evaluation of current accessed circuitry for various memory functions. The design, fabrication, and test of four device designs is described, and a recommended memory storage area configuration is presented. Memory functions which were demonstrated include the current accessed propagation of bubble domains and stripe domains, pinning of stripe domain ends, generation of single and double bubbles, generation of arrays of coexisting strip and bubble domains in a single garnet layer, and demonstration of different values of the strip out field for single and double bubbles indicating adequate margins for data detection. All functions necessary to develop a multilayer self structured bubble memory device were demonstrated in individual experiments.

Torok, E. J.; Kamin, M.; Tolman, C. H.

1980-01-01

257

Transverse thermoelectric response of a tilted metallic multilayer structure  

NASA Astrophysics Data System (ADS)

Thermoelectric fields transverse to an applied temperature gradient have been observed in artificially created tilted multilayer structures. Copper-constantan multilayer structures were prepared by sintering of a compressed stack of copper/constantan/copper foils and by cutting the stack obliquely to its axis. Tilted multilayer structures represent a new class of thermoelectric devices, and applications for detection of light are demonstrated.

Zahner, Th.; Förg, R.; Lengfellner, H.

1998-09-01

258

Voltage drop at interfaces in multilayer ferroelectrics  

NASA Astrophysics Data System (ADS)

Based upon a defined surface barrier in ferroelectric multilayers deposited on (100) p-type silicon, ?Va, which bears a portion of the external electrical voltage, a modified empirical power law I=A(?V)n is established for quantitatively describing detailed I-V dependence in ferroelectric multilayers. The voltage drop at the interface, Vi, which directly affects electrical characteristics of ferroelectric multiplayer system, is studied thoroughly. The voltage drop obtained from the modified empirical power law of the I-V dependence is consistent with that obtained from the C-V dependence model.

Li, Xingjiao; Wang, Ningzhang; Bao, Junbo; Chen, Tao; Xu, Jingping; Feng, Hanhua; Li, Shaoping

2003-03-01

259

Lead-free multilayer piezoelectric transformer  

Microsoft Academic Search

In this article, a multilayer piezoelectric transformer based on lead-free Mn-doped 0.94(Bi1\\/2Na1\\/2)TiO3-0.06BaTiO3 ceramics is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, is 8.3 mm long, 8.3 mm wide, and 2.3 mm thick. It operates in the second thickness extensional vibration mode. For a temperature rise of 20 °C, the transformer has an output power of

Mingsen Guo; X. P. Jiang; K. H. Lam; S. Wang; C. L. Sun; Helen L. W. Chan; X. Z. Zhao

2007-01-01

260

Synthesis and electrical conductivity of multilayer silicene  

NASA Astrophysics Data System (ADS)

The epitaxial growth and the electrical resistance of multilayer silicene on the Ag(111) surface has been investigated. We show that the atomic structure of the first silicene layer differs from the next layers and that the adsorption of Si induces the formation of extended silicene terraces surrounded by step bunching. Thanks to the controlled contact formation between the tips of a multiple probe scanning tunneling microscope and these extended terraces, a low sheet resistance, albeit much higher than the electrical resistance of the underlying silver substrate, has been measured, advocating for the electrical viability of multilayer silicene.

Vogt, P.; Capiod, P.; Berthe, M.; Resta, A.; De Padova, P.; Bruhn, T.; Le Lay, G.; Grandidier, B.

2014-01-01

261

Thermal diffusion in Ni/Al multilayer  

SciTech Connect

Two Ni/Al multilayers deposited by ion beam sputtering of nominal design [Ni(200A)/Al(100A)] Multiplication-Sign 5 and [Ni(50A)/Al(227A)] Multiplication-Sign 5 on Si substrates were annealed at 200 Degree-Sign C. As-deposited and annealed samples were characterized by x-ray diffraction (XRD) and x-ray reflectometry (XRR). The effort was to study the path of alloying in the above two multilayers of same elements but of opposite stoichiometric ratio. We find distinct differences in alloying of these samples.

Swain, M.; Bhattacharya, D.; Singh, S.; Basu, S. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Gupta, M. [UGC-DAE-Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

2013-02-05

262

Spontaneous reorientation of bimetal multilayer nanowires  

SciTech Connect

Multilayered structures are proposed to extend the size range at which metal nanowires can transform spontaneously from one orientation to another due to the interfacial stress. The principle is demonstrated on gold-palladium (Au-Pd) multilayer nanowires by using the molecular dynamics (MD) method and two distinctly different mechanisms are identified for the reorientation which take place mainly via slipping and twinning at low temperature and by amorphization and recrystallization at high temperature. Our results show that the time response of devices fabricated with the nanostructures is consequently affected.

Ma Fei; Ma Shengli; Xu Kewei; Chu, Paul K. [State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049 Shaanxi (China) and Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong (China); State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049 Shaanxi (China); Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong (China)

2007-12-17

263

Thermal stability of Co/C multilayers  

NASA Astrophysics Data System (ADS)

The structural and interface changes induced by thermal annealing in Co/C multilayers were investigated. Co/C multilayers with period thickness of 4.1 nm and bi-layer number of 20 were deposited by direct current magnetron sputtering. We characterized all samples by using x-ray reflectivity, x-ray diffuse scattering, zero-field nuclear magnetic resonance spectroscopy and x-ray diffraction. The results indicate that Co and C atoms mixed during deposition and then after annealing both atoms separated from their mixed region. The annealing process also causes a sharp increase of roughness at interfaces, which can be attributed to the crystallization of Co layers.

Zhu, Jingtao; Tu, Yuchun; Yuan, Yanyan; Feng, Zhixiang; Li, Haochuan; Zhang, Yizhi; Jonnard, Philippe; Mény, Christian; Le Guen, Karine; André, Jean-Michel; Wang, Zhanshan

2014-12-01

264

Magnetic Multilayers I Andreas Moser, Chairman Magnetism and structure of Fe/Cu multilayers studied by low-temperature  

E-print Network

, structure, and morphology of a (Cu 39 Ã?/Fe 7 Ã?) 36 multilayer prepared by dc magnetron sputtering were/Cu multilayers pre- pared by ion beam sputtering, magnetron sputtering, thermal evaporation, and electron beam, and morphology. II. EXPERIMENTAL METHODS Fe/Cu multilayers were prepared by dc magnetron sput- tering of 36

Ryan, Dominic

265

Dustiness of Fine and Nanoscale Powders  

PubMed Central

Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3–37.9% and 0.1–31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300nm to several micrometers, but no modes below 100nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100nm particle contribution in a workplace. PMID:23065675

Evans, Douglas E.; Baron, Paul A.

2013-01-01

266

Preparation and characterization on nano-hybrid composite solid polymer electrolyte of PVdF-HFP /MG49-ZrO2 for battery application  

NASA Astrophysics Data System (ADS)

Initial study on nano composite polymer electrolyte of PVdF-HFP/MG49-ZrO2 has been done. The zirconium was synthesis via in-situ sol-gel method in a dissolved polymer blends. The effects of different concentrations of zirconium and pH values have been investigated on nano composite polymer (NCP). Analysis impedance show that only at 6 wt. % of zirconium for all pH values show a semi-circle arc which have lowest value of bulk resistance. No ionic conductivity value is obtain due to the absent of ion charge carriers. Analysis of XRD revealed that crystallinity phase of the nano composite polymer was affect by different pH values. However, no significant changes have been observed in IR bands. This could well indicate that different pH medium did not affect the chemical bonding in the structure.

Lee T., K.; Ahmad, A.; Hasyareeda, N.

2014-09-01

267

Preparation by PVD of Er/Ce-doped PZG fluoride glass channel waveguide for integrated optical amplifiers at 1.5 ?m  

NASA Astrophysics Data System (ADS)

The fabrication by physical vapor deposition (PVD) of Er/Ce-doped fluoride glass channel waveguides using low cost silica on silicon (SiO 2/Si) engraved cleavable substrates was demonstrated. The mean composition of the deposited glass was 38PbF 2-19ZnF 2-43GaF 3 in mol% with Er and Ce concentrations fixed at 1 mol%. The channel waveguides with cross-sectional dimensions 3 × 2 ?m 2 were single-mode at 0.63 ?m. Propagation losses of less than 0.5 dB/cm and loss reduction of 3.3 dB/cm were measured at 1.535 ?m in a 3.2 cm long waveguide with an absorbed power of about 3 mW at 0.98 ?m.

Gao, Youping; Boulard, Brigitte; Couchaud, Maurice; Vasilief, Ion; Guy, Stéphan; Duverger, Claire; Jacquier, Bernard

2006-02-01

268

Defect-tolerant extreme ultraviolet nanoscale printing.  

PubMed

We present a defect-free lithography method for printing periodic features with nanoscale resolution using coherent extreme ultraviolet light. This technique is based on the self-imaging effect known as the Talbot effect, which is produced when coherent light is diffracted by a periodic mask. We present a numerical simulation and an experimental verification of the method with a compact extreme ultraviolet laser. Furthermore, we explore the extent of defect tolerance by testing masks with different defect layouts. The experimental results are in good agreement with theoretical calculations. PMID:22940973

Urbanski, L; Isoyan, A; Stein, A; Rocca, J J; Menoni, C S; Marconi, M C

2012-09-01

269

Long Range Interactions in Nanoscale Science  

SciTech Connect

Our understanding of the long range electrodynamic, electrostatic, and polar interactions that dominate the organization of small objects at separations beyond an interatomic bond length is reviewed. From this basic-forces perspective, a large number of systems are described from which one can learn about these organizing forces and how to modulate them. The many practical systems that harness these nanoscale forces are then surveyed. The survey reveals not only the promise of new devices and materials, but also the possibility of designing them more effectively.

French, Roger H [DuPont Company; Parsegian, V Adrian [National Institutes of Health; Podgonik, Rudolph [National Institutes of Health; Rajter, Rick [Massachusetts Institute of Technology (MIT); Jagota, Anand [Lehigh University, Bethlehem, PA; Luo, Jian [Clemson University; Asthagiri, Dilip [Johns Hopkins University; Chaudhury, Manoj [Lehigh University, Bethlehem, PA; Chiang, Yet-Ming [Massachusetts Institute of Technology (MIT); Granick, Steve [University of Illinois, Urbana-Champaign; Kalinin, Sergei V [ORNL; Kardar, Mehran [Massachusetts Institute of Technology (MIT); Kjellander, Roland [University of Gothenburg, Sweden; Langreth, David C. [Rutgers University; Lewis, Jennifer [University of Illinois, Urbana-Champaign; Lustig, Steve [DuPont Company; Wesolowski, David J [ORNL; Wettlaufer, John [Yale University; Ching, Wai-Yim [University of Missouri; Finnis, Mike [Imperial College, London; Houlihan, Frank [AZ Electronic Materials Corporation, USA; Von Lilienfeld, O. Anatole [Sandia National Laboratories (SNL); Van Oss, Carel [University of Buffalo, The State University of New York; Zemb, Thomas [Institut de Chimie de la Matiere Condensee de Bordeaux, France

2010-01-01

270

Bumpy, Sticky, and Shaky: Nanoscale Science and the Curriculum  

ERIC Educational Resources Information Center

Nanoscience, or the study of the world at the size of a billionth of a meter, has the potential to help students see how all of the sciences are related. Behavior of materials at the nanoscale differs from materials at the macroscale. This article introduces three nanoscale properties and how they relate to various science domains. Three…

Taylor, Amy; Jones, Gail; Pearl, Thomas P.

2008-01-01

271

Technology Review: Nanoscale Inkjet Printing TechnologyReview.  

E-print Network

Technology Review: Nanoscale Inkjet Printing My. TechnologyReview. com: > Login > Register Home, 2007 Nanoscale Inkjet Printing E-jet printing of precise structures out of various materials could prove to be a valuable tool in nano manufacturing. By Duncan Graham-Rowe q Print q E-mail q Audio » New

Rogers, John A.

272

Cell Mechanotransduction: Cell ResponsesTo NanoscaleVibrations  

E-print Network

and for stem cell transplant Can use osteogenic chemicals however not always in vivo Image of cellular-scale patterns Nanoscale topographies being produced via electron beam lithography Mesenchymal stem cells (MSCCell Mechanotransduction: Cell ResponsesTo NanoscaleVibrations Peter Childs, Stuart Reid, Fiona

Greenaway, Alan

273

Quantifying Nanoscale Order in Amorphous Materials via Fluctuation Electron Microscopy  

ERIC Educational Resources Information Center

Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function…

Bogle, Stephanie Nicole

2009-01-01

274

Polyelectrolyte Multilayers Containing Polyethylene-based Ionomers  

E-print Network

Layer-by-Layer (LbL) assembly technique is a powerful approach to blend two or more materials to form new materials of thin films on any type of substrate, and the LbL film is called polyelectrolyte multilayers (PEMs). The assemblies are highly...

Huang, Hsiu-Chin

2014-08-14

275

Scattering and absorption by spherical multilayer particles  

NASA Astrophysics Data System (ADS)

We present a recursion formalism for the scattering coefficients of multilayered spherical particles which is more treatable for computer programs than the matrixformalism of Bhandari [1]. We computed explicitely the extinction and scattering cross section spectra of different metal coated spheres. Comparison with experimental results is done for gold-silver heterosystems. The spectra are in very good agreement with the experimental data.

Sinzig, J.; Quinten, M.

1994-02-01

276

Multilayered Governance, Pluralism, and Moral Conflict  

Microsoft Academic Search

The quest for multilayered governance faces the problem of endemic tensions and disagreements in international relations and doubts as to whether nations truly share common values upon which an international society can be solidly built. Values, however, are equally controversial within the nation-state. We find similar tensions within domestic and regional layers of governance. In any system of governance, diverging

Thomas Cottier

2009-01-01

277

Destruction Mechanisms in Ceramic Multilayer Actuators  

Microsoft Academic Search

Destruction mechanisms were investigated in electrostrictor, piezoelectric and phase-change antiferroelectric ceramic multilayer actuators with an interdigital electrode configuration. Simultaneous observations were done by three different methods; visual observation with a charge coupled device (CCD) microscope, field-induced strain and acoustic emission (AE) measurements. During a cyclic electric field application, the crack was initiated from the edge of an internal electrode and

Hideaki Aburatani; Shuichi Harada; Kenji Uchino; Atsushi Furuta; Yoshiaki Fuda

1994-01-01

278

Purging of multilayer insulation by gas diffusion  

Microsoft Academic Search

An experimental investigation was conducted to determine the time required to purge a multilayer insulation (MLI) panel with gaseous helium by means of gas diffusion to obtain a condensable (nitrogen) gas concentration of less than 1 percent within the panel. Two flat, rectangular MLI panel configurations, one incorporating a butt joint, were tested. The insulation panels consisted of 15 double-aluminized

I. E. Sumner; C. M. Spuckler

1976-01-01

279

RADIATION MULTILAYER SHIELD IN THE REACTOR  

Microsoft Academic Search

The design of the reactor radiation shield is an integrated multistep process and consists of interdependent stages. On it's early stages the approximate calculation methods with different accuracy may be applied. We consider here a semi-empirical calculation model of radiation multilayer shield in the reactor having the core and shield configuration-infinite slab. Numerical calculations for three different geometrical configurations (infinite

LE VAN NGOC

2002-01-01

280

Performance of multilayer insulation with slotted shield  

Microsoft Academic Search

Thermal and evacuating performance can be improved by means of slotting a number of one dimension slots on reflection shields of the multilayer insulation (MLI). The influence of slots on thermal radiation and gas conduction heat fluxes are theoretically studied. Based on the analysis and test, the optimum slot rate and length have been obtained. Experiments also show that the

Guobang Chen; Tao Sun; Jianyao Zheng; Zhixue Huang; Jianping Yu

1994-01-01

281

Enhanced thermal transport in strongly correlated multilayered  

E-print Network

, the transport crosses over to being thermally activated in an insulator and is no longer governed by tunnelingEnhanced thermal transport in strongly correlated multilayered nanostructures J. K. Freericks, thermoelectric coolers, spintronic devices, etc. · Band insulators: AlOx MgO · Correlated materials: FeSi, SrTiO3

Freericks, Jim

282

Giant magnetoresistance in magnetic multilayered nanowires  

Microsoft Academic Search

Giant magnetoresistance (GMR) is observed in a new type of nanostructured material consisting of magnetic multilayered nanowires formed by electrodeposition into nanometer-sized pores of a template polymer membrane. The composition of these nanowires is modulated over nanometer length scales with distinct magnetic and nonmagnetic metallic layers. Magnetoresistance measurements with the current perpendicular to the layers were performed on the array

L. Piraux; J. M. George; J. F. Despres; C. Leroy; E. Ferain; R. Legras; K. Ounadjela; A. Fert

1994-01-01

283

Giant magnetoresistance in spin-valve multilayers  

Microsoft Academic Search

A comprehensive review of giant magnetoresistance in spin-valve sandwiches and multilayers is presented, highlighting the experimental and theoretical results which are of particular interest for the development of applications of these systems, especially in magnetic recording technology. The main points discussed include the physical origin of the giant magnetoresistance, the influence of the thicknesses of the magnetic and nonmagnetic layers,

B. Dieny

1994-01-01

284

Coherent multilayer crystals and method of making  

DOEpatents

A new material consisting of a multilayer crystalline structure which is coherent perpendicular to the layers and where each layer is composed of a single crystalline element. The individual layers may vary from 2.ANG. to 100.ANG. or more in thickness.

Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Tucson, AZ)

1984-01-01

285

Numerical simulation and experiment on multilayer stagger-split die  

NASA Astrophysics Data System (ADS)

A novel ultra-high pressure device, multilayer stagger-split die, has been constructed based on the principle of "dividing dies before cracking." Multilayer stagger-split die includes an encircling ring and multilayer assemblages, and the mating surfaces of the multilayer assemblages are mutually staggered between adjacent layers. In this paper, we investigated the stressing features of this structure through finite element techniques, and the results were compared with those of the belt type die and single split die. The contrast experiments were also carried out to test the bearing pressure performance of multilayer stagger-split die. It is concluded that the stress distributions are reasonable and the materials are utilized effectively for multilayer stagger-split die. And experiments indicate that the multilayer stagger-split die can bear the greatest pressure.

Liu, Zhiwei; Li, Mingzhe; Han, Qigang; Yang, Yunfei; Wang, Bolong; Sui, Zhou

2013-05-01

286

Nano-Scale Effects in Cylindrical Contacts Sari et al. NANO-SCALE EFFECTS IN THE ADHERENCE, SLIDING  

E-print Network

@coe.neu.edu Abstract The behavior of a nano-scale cylindrical body (e.g. a fiber), lying on a substrate and acted uponNano-Scale Effects in Cylindrical Contacts Sari et al. 1 NANO-SCALE EFFECTS IN THE ADHERENCE to the nano level, adhesion becomes an important issue in this contact problem. Thus this investigation treats

Müftü, Sinan

287

Channeling technique to make nanoscale ion beams  

NASA Astrophysics Data System (ADS)

Particle channeling in a bent crystal lattice has led to an efficient instrument for beam steering at accelerators [Biryukov et al., Crystal Channeling and its Application at High Energy Accelerators, Springer, Berlin, 1997], demonstrated from MeV to TeV energies. In particular, crystal focusing of high-energy protons to micron size has been demonstrated at IHEP with the results well in match with Lindhard (critical angle) prediction. Channeling in crystal microstructures has been proposed as a unique source of a microbeam of high-energy particles [Bellucci et al., Phys. Rev. ST Accel. Beams 6 (2003) 033502]. Channeling in nanostructures (single-wall and multi-wall nanotubes) offers the opportunities to produce ion beams on nanoscale. Particles channeled in a nanotube (with typical diameter of about 1 nm) are trapped in two dimensions and can be steered (deflected, focused) with the efficiency similar to that of crystal channeling or better. This technique has been a subject of computer simulations, with experimental efforts under way in several high-energy labs, including IHEP. We present the theoretical outlook for making channeling-based nanoscale ion beams and report the experience with crystal-focused microscale proton beams.

Biryukov, V. M.; Bellucci, S.; Guidi, V.

2005-04-01

288

Visualizing copper assisted graphene growth in nanoscale  

PubMed Central

Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp2 hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction. PMID:25523645

Rosmi, Mohamad Saufi; Yusop, Mohd Zamri; Kalita, Golap; Yaakob, Yazid; Takahashi, Chisato; Tanemura, Masaki

2014-01-01

289

Transport and structure in nanoscale channels  

NASA Astrophysics Data System (ADS)

Driven by the rapidly advancing fields of nano- and biotechnology, there has been an explosion of interest in molecular transport and structure formation on small length scales. A canonical model for the transport of particles along one dimensional pathways in nanoscale channels is the Totally Asymmetric Simple Exclusion Process (TASEP). After introducing the standard TASEP, modifications of the TASEP designed to increase its utility in modeling biological transport processes are described. One variant of the TASEP is particularly suitable for modeling protein translation, and the results of using this variant to investigate the effects of slow-codons on the translation process are discussed. A related topic is the voltage-driven translocation of DNA hairpins through membrane-embedded nanopores. Motivated by recent experiments, a stochastic model is developed that couples the translocation and dehybridization of the DNA hairpin. This model is used to explore the behaviour of the mean translocation time of hairpins as a function of driving voltage, and two translocation mechanisms are identified and discussed. Finally, the adsorption and equilibrium structures of water in the interior of ion-bearing nanoscale pores are considered. The behaviour of water and ions under confinement is critical to the functioning of biological ion channels and nanoporous filters. Here, the adsorption isotherms of water are examined, and the layered structures formed by the confined water are described.

Lakatos, Gregory William

290

Nanoscale Charge Transport in Excitonic Solar Cells  

SciTech Connect

Excitonic solar cells, including all-organic, hybrid organic-inorganic and dye-sensitized solar cells (DSSCs), offer strong potential for inexpensive and large-area solar energy conversion. Unlike traditional inorganic semiconductor solar cells, where all the charge generation and collection processes are well understood, these excitonic solar cells contain extremely disordered structures with complex interfaces which results in large variations in nanoscale electronic properties and has a strong influence on carrier generation, transport, dissociation and collection. Detailed understanding of these processes is important for fabrication of highly efficient solar cells. Efforts to improve efficiency are underway at a large number of research groups throughout the world focused on inorganic and organic semiconductors, photonics, photophysics, charge transport, nanoscience, ultrafast spectroscopy, photonics, semiconductor processing, device physics, device structures, interface structure etc. Rapid progress in this multidisciplinary area requires strong synergetic efforts among researchers from diverse backgrounds. Such effort can lead to novel methods for development of new materials with improved photon harvesting and interfacial treatments for improved carrier transport, process optimization to yield ordered nanoscale morphologies with well defined electronic structures.

Venkat Bommisetty, South Dakota State University

2011-06-23

291

Poroelasticity of Cartilage at the Nanoscale  

PubMed Central

Atomic-force-microscopy-based oscillatory loading was used in conjunction with finite element modeling to quantify and predict the frequency-dependent mechanical properties of the superficial zone of young bovine articular cartilage at deformation amplitudes, ?, of ?15 nm; i.e., at macromolecular length scales. Using a spherical probe tip (R ? 12.5 ?m), the magnitude of the dynamic complex indentation modulus, |E?|, and phase angle, ?, between the force and tip displacement sinusoids, were measured in the frequency range f ? 0.2–130 Hz at an offset indentation depth of ?0 ? 3 ?m. The experimentally measured |E?| and ? corresponded well with that predicted by a fibril-reinforced poroelastic model over a three-decade frequency range. The peak frequency of phase angle, fpeak, was observed to scale linearly with the inverse square of the contact distance between probe tip and cartilage, 1/d2, as predicted by linear poroelasticity theory. The dynamic mechanical properties were observed to be independent of the deformation amplitude in the range ? = 7–50 nm. Hence, these results suggest that poroelasticity was the dominant mechanism underlying the frequency-dependent mechanical behavior observed at these nanoscale deformations. These findings enable ongoing investigations of the nanoscale progression of matrix pathology in tissue-level disease. PMID:22067171

Nia, Hadi Tavakoli; Han, Lin; Li, Yang; Ortiz, Christine; Grodzinsky, Alan

2011-01-01

292

Visualizing copper assisted graphene growth in nanoscale  

NASA Astrophysics Data System (ADS)

Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp2 hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction.

Rosmi, Mohamad Saufi; Yusop, Mohd Zamri; Kalita, Golap; Yaakob, Yazid; Takahashi, Chisato; Tanemura, Masaki

2014-12-01

293

Visualizing copper assisted graphene growth in nanoscale.  

PubMed

Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp(2) hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction. PMID:25523645

Rosmi, Mohamad Saufi; Yusop, Mohd Zamri; Kalita, Golap; Yaakob, Yazid; Takahashi, Chisato; Tanemura, Masaki

2014-01-01

294

Can amorphization take place in nanoscale interconnects?  

PubMed

The trend of miniaturization has highlighted the problems of heat dissipation and electromigration in nanoelectronic device interconnects, but not amorphization. While amorphization is known to be a high pressure and/or temperature phenomenon, we argue that defect density is the key factor, while temperature and pressure are only the means. For nanoscale interconnects carrying modest current density, large vacancy concentrations may be generated without the necessity of high temperature or pressure due to the large fraction of grain boundaries and triple points. To investigate this hypothesis, we performed in situ transmission electron microscope (TEM) experiments on 200 nm thick (80 nm average grain size) aluminum specimens. Electron diffraction patterns indicate partial amorphization at modest current density of about 10(5) A cm(-2), which is too low to trigger electromigration. Since amorphization results in drastic decrease in mechanical ductility as well as electrical and thermal conductivity, further increase in current density to about 7 × 10(5) A cm(-2) resulted in brittle fracture failure. Our molecular dynamics (MD) simulations predict the formation of amorphous regions in response to large mechanical stresses (due to nanoscale grain size) and excess vacancies at the cathode side of the thin films. The findings of this study suggest that amorphization can precede electromigration and thereby play a vital role in the reliability of micro/nanoelectronic devices. PMID:22322399

Kumar, S; Joshi, K L; van Duin, A C T; Haque, M A

2012-03-01

295

Light-driven nanoscale plasmonic motors.  

PubMed

When Sir William Crookes developed a four-vaned radiometer, also known as the light-mill, in 1873, it was believed that this device confirmed the existence of linear momentum carried by photons, as predicted by Maxwell's equations. Although Reynolds later proved that the torque on the radiometer was caused by thermal transpiration, researchers continued to search for ways to take advantage of the momentum of photons and to use it for generating rotational forces. The ability to provide rotational force at the nanoscale could open up a range of applications in physics, biology and chemistry, including DNA unfolding and sequencing and nanoelectromechanical systems. Here, we demonstrate a nanoscale plasmonic structure that can, when illuminated with linearly polarized light, generate a rotational force that is capable of rotating a silica microdisk that is 4,000 times larger in volume. Furthermore, we can control the rotation velocity and direction by varying the wavelength of the incident light to excite different plasmonic modes. PMID:20601945

Liu, Ming; Zentgraf, Thomas; Liu, Yongmin; Bartal, Guy; Zhang, Xiang

2010-08-01

296

Polyelectrolyte multilayers: An odyssey through interdisciplinary science  

NASA Astrophysics Data System (ADS)

This dissertation provides an overview of a self assembled multilayer technique based on the alternating deposition of oppositely charged polyelectrolytes onto charged solid supports. The basic principles and methodologies governing this technique are laid down, and new strategies are built upon the latter, in an effort to develop innovative technologies that would be beneficial for making new products or improving the quality of existing ones. Fundamental studies to characterize the water content, efficiency of ion-pairing, differential strength of electrostatic interactions, topology, and viscoelastic properties of polyelectrolyte multilayers, PEMUs, are illustrated and conducted. In addition, polyelectrolyte multilayers that are stimulus responsive, or support active and controlled bio-motor protein interactions are described. Attenuated total reflectance Fourier transform infrared, (ATR), spectroscopy was used to compare the extent of swelling and doping within PAH/PSS and PDADMA/PSS polyelectrolyte multilayers. Unlike PDADMA/PSS, whose water content depended on the solution ionic strength, PAH/PSS was resistant to swelling by salt. It was stable up to 4.0 M sodium chloride, with 6 water molecules per ion-pair. Using the infrared active perchlorate sodium salt, the amount of residual persistent extrinsic sites in both PDADMA/PSS and PAH/PSS was determined to be 3% and 6%, respectively. The free energy of association between the polymer segments, in the presence of sodium perchlorate, was in the order of 4.5 kJ mol-1 and -9.5 kJ mol-1 for PDADMA/PSS and PAH/PSS correspondingly. Thus, indicating the relatively strong electrostatic association between the polymer segments in a PAH/PSS relative to PDADMA/PSS multilayer. Adjusting the pH of the solution in contact with the PAH/PSS multilayer to 11.5 resulted in a first order discontinuous dissociation of the Pol+Pol- bonds. Techniques used to study the mechanical properties of single muscle fiber were adapted to characterize the topology, viscoelastic behavior, complex modulus and loss factor of PDADMA/PSS multilayers, over a range of frequencies and strain amplitudes. Tensile mode (transient uniaxial stretching) of a PEMU microcoupon using a capacitative-type force transducer located on a modified stage of inverted microscope revealed evidence on the viscous-like behavior of polymer chains within PEMU. Dependence of viscosity was primarily on the ionic strength of the bathing solution, with appreciable stress relaxation occurring at high salt concentrations. Dynamic mechanical analysis was then used to determine the damping properties of PEMU where the length was oscillated sinusoidally, and the resulting force, amplitude and phase shift were observed. Compared to other commercially available polymer damping materials such as acrylic and rubber adhesives, PEMU demonstrated up to 250% enhancement in damping properties over the frequency range of 0.3-10 Hz. This was obtained while the multilayer dry thickness was 3000% less then that of the conventional adhesives. The synthesis of charged copolymers of poly(N-isopropylacrylamide), (PNIPAM), and their use in constructing thermally responsive PEMU were demonstrated. The temperature dependent water content of the thin film, studied in situ using ATR-FTIR spectroscopy, revealed microscopic and macroscopic transitions at 33 and 45°C, respectively. About 7 water molecules per NIPAM repeat unit were found to be reversibly lost from, or recovered by, the film upon cycling over a temperature range of 10 to 55°C. Assuming that each ion-pair represents a crosslink, swelling theory was used to translate these results into polymer-solvent interaction parameters and enthalpies of mixing for the various polymer components. In addition, the flux of a charged probe molecule, potassium ferricyanide, through the NIPAM-rich multilayer was assessed with rotating disk electrode voltammetry. Thermally reversible modulation of ion transport was demonstrated. Positive polyelectrolytes were investigated as new surface coatings for promoting in vi

Jaber, Jad A.

297

Method to adjust multilayer film stress induced deformation of optics  

DOEpatents

Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

Spiller, Eberhard A. (Mount Kisco, NY); Mirkarimi, Paul B. (Sunol, CA); Montcalm, Claude (Livermore, CA); Bajt, Sasa (Sunol, CA); Folta, James A. (Livermore, CA)

2000-01-01

298

Design and development of multilayer vascular graft  

NASA Astrophysics Data System (ADS)

Vascular graft is a widely-used medical device for the treatment of vascular diseases such as atherosclerosis and aneurysm as well as for the use of vascular access and pediatric shunt, which are major causes of mortality and morbidity in this world. Dysfunction of vascular grafts often occurs, particularly for grafts with diameter less than 6mm, and is associated with the design of graft materials. Mechanical strength, compliance, permeability, endothelialization and availability are issues of most concern for vascular graft materials. To address these issues, we have designed a biodegradable, compliant graft made of hybrid multilayer by combining an intimal equivalent, electrospun heparin-impregnated poly-epsilon-caprolactone nanofibers, with a medial equivalent, a crosslinked collagen-chitosan-based gel scaffold. The intimal equivalent is designed to build mechanical strength and stability suitable for in vivo grafting and to prevent thrombosis. The medial equivalent is designed to serve as a scaffold for the activity of the smooth muscle cells important for vascular healing and regeneration. Our results have shown that genipin is a biocompatible crosslinker to enhance the mechanical properties of collagen-chitosan based scaffolds, and the degradation time and the activity of smooth muscle cells in the scaffold can be modulated by the crosslinking degree. For vascular grafting and regeneration in vivo, an important design parameter of the hybrid multilayer is the interface adhesion between the intimal and medial equivalents. With diametrically opposite affinities to water, delamination of the two layers occurs. Physical or chemical modification techniques were thus used to enhance the adhesion. Microscopic examination and graft-relevant functional characterizations have been performed to evaluate these techniques. Results from characterization of microstructure and functional properties, including burst strength, compliance, water permeability and suture strength, showed that the multilayer graft possessed properties mimicking those of native vessels. Achieving these FDA-required functional properties is essential because they play critical roles in graft performances in vivo such as thrombus formation, occlusion, healing, and bleeding. In addition, cell studies and animal studies have been performed on the multilayer graft. Our results show that the multilayer graft support mimetic vascular culture of cells and the acellular graft serves as an artery equivalent in vivo to sustain the physiological conditions and promote appropriate cellular activity. In conclusion, the newly-developed hybrid multilayer graft provides a proper balance of biomechanical and biochemical properties and demonstrates the potential for the use of vascular tissue engineering and regeneration.

Madhavan, Krishna

2011-07-01

299

Characterization Of Multi-layered Fish Scales (Atractosteus spatula) Using Nanoindentation, X-ray CT, FTIR, and SEM  

PubMed Central

The hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram’s horn, antlers, and turtle shells provides unique design principles with potentials for guiding the design of protective materials and systems in the future. Understanding the structure-property relationships for these material systems at the microscale and nanoscale where failure initiates is essential. Currently, experimental techniques such as nanoindentation, X-ray CT, and SEM provide researchers with a way to correlate the mechanical behavior with hierarchical microstructures of these material systems1-6. However, a well-defined standard procedure for specimen preparation of mineralized biomaterials is not currently available. In this study, the methods for probing spatially correlated chemical, structural, and mechanical properties of the multilayered scale of A. spatula using nanoindentation, FTIR, SEM, with energy-dispersive X-ray (EDX) microanalysis, and X-ray CT are presented. PMID:25046233

Allison, Paul G.; Rodriguez, Rogie I.; Moser, Robert D.; Williams, Brett A.; Poda, Aimee R.; Seiter, Jennifer M.; Lafferty, Brandon J.; Kennedy, Alan J.; Chandler, Mei Q.

2014-01-01

300

Detecting nanoscale vibrations as signature of life.  

PubMed

The existence of life in extreme conditions, in particular in extraterrestrial environments, is certainly one of the most intriguing scientific questions of our time. In this report, we demonstrate the use of an innovative nanoscale motion sensor in life-searching experiments in Earth-bound and interplanetary missions. This technique exploits the sensitivity of nanomechanical oscillators to transduce the small fluctuations that characterize living systems. The intensity of such movements is an indication of the viability of living specimens and conveys information related to their metabolic activity. Here, we show that the nanomotion detector can assess the viability of a vast range of biological specimens and that it could be the perfect complement to conventional chemical life-detection assays. Indeed, by combining chemical and dynamical measurements, we could achieve an unprecedented depth in the characterization of life in extreme and extraterrestrial environments. PMID:25548177

Kasas, Sandor; Ruggeri, Francesco Simone; Benadiba, Carine; Maillard, Caroline; Stupar, Petar; Tournu, Hélène; Dietler, Giovanni; Longo, Giovanni

2015-01-13

301

Virtual Journal of Nanoscale Science and Technology  

NSDL National Science Digital Library

Featured here is an important subscription-based resource for obtaining science articles online. Wide-ranging institutional access as well as free services make this resources useful without an individual subscription. In addition, in January 2000, the American Institute of Physics (AIP) and the American Physical Society (APS) launched a new virtual journal. Representing the first entry in a series of journals the Virtual Journal of Nanoscale Science and Technology will gather "into one spot all the papers on a given topic that appear in a wide range of premier physics-related journals." The articles have been pre-selected by expert editors, so that specialists may turn to this convenient resource to stay on top of cutting-edge research. Access to articles will require a regular subscription to the specific journals, though non-subscribers do have the option of purchasing individual articles for immediate online delivery. Browsing the tables of contents and abstracts is free.

302

Energy Conversion at Micro and Nanoscale  

NASA Astrophysics Data System (ADS)

Energy management is considered a task of strategic importance in contemporary society. It is a common fact that the most successful economies of the planet are the economies that can transform and use large quantities of energy. In this talk we will discuss the role of energy with specific attention to the processes that happens at micro and nanoscale. The description of energy conversion processes at these scales requires approaches that go way beyond the standard equilibrium termodynamics of macroscopic systems. In this talk we will address from a fundamental point of view the physics of the dissipation of energy and will focus our attention to the energy transformation processes that take place in the modern micro and nano information and communication devices.

Gammaitoni, Luca

2014-11-01

303

Exploring Carbon Nanotubes for Nanoscale Devices  

NASA Technical Reports Server (NTRS)

Carbon nanotubes (CNTs) are shown to promise great opportunities in nanoelectronic devices and nanoelectromechanical systems (NEMS) because of their inherent nanoscale sizes, intrinsic electric conductivities, and seamless hexagonal network architectures. I present our collaborative work with Stanford on exploring CNTs for nanodevices in this talk. The electrical property measurements suggest that metallic tubes are quantum wires. Furthermore, two and three terminal CNT junctions have been observed experimentally. We have proposed and studied CNT-based molecular switches and logic devices for future digital electronics. We also have studied CNTs based NEMS inclusing gears, cantilevers, and scanning probe microscopy tips. We investigate both chemistry and physics based aspects of the CNT NEMS. Our results suggest that CNT have ideal stiffness, vibrational frequencies, Q-factors, geometry-dependent electric conductivities, and the highest chemical and mechanical stabilities for the NEMS. The use of CNT SPM tips for nanolithography is presented for demonstration of the advantages of the CNT NEMS.

Han, Jie; Dai; Anantram; Jaffe; Saini, Subhash (Technical Monitor)

1998-01-01

304

Preface: Charge transport in nanoscale junctions  

NASA Astrophysics Data System (ADS)

Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at the molecular level. Nanoscale charge transport experiments in ionic liquids extend the field to high temperatures and to systems with intriguing interfacial potential distributions. Other directions may include dye-sensitized solar cells, new sensor applications and diagnostic tools for the study of surface-bound single molecules. Another motivation for this special issue is thus to highlight activities across different research communities with nanoscale charge transport as a common denominator. This special issue gathers 27 articles by scientists from the United States, Germany, the UK, Denmark, Russia, France, Israel, Canada, Australia, Sweden, Switzerland, the Netherlands, Belgium and Singapore; it gives us a flavour of the current state-of-the-art of this diverse research area. While based on contributions from many renowned groups and institutions, it obviously cannot claim to represent all groups active in this very broad area. Moreover, a number of world-leading groups were unable to take part in this project within the allocated time limit. Nevertheless, we regard the current selection of papers to be representative enough for the reader to draw their own conclusions about the current status of the field. Each paper is original and has its own merit, as all papers in Journal of Physics: Condensed Matter special issues are subjected to the same scrutiny as regular contributions. The Guest Editors have deliberately not defined the specific subjects covered in this issue. These came out logically from the development of this area, for example: 'Traditional' solid state nanojunctions based on adsorbed layers, oxide films or nanowires sandwiched between two electrodes: effects of molecular structure (aromaticity, anchoring groups), symmetry, orientation, dynamics (noise patterns) and current-induced heating. Various 'physical effects': inelastic tunnelling and Coulomb blockade, polaron effects, switching modes, and negative differential resistance; the role of many particle excitations, new surface states in semiconductor electrodes, various mechanisms for

Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

2008-09-01

305

Fundamental effects in nanoscale thermocapillary flow  

NASA Astrophysics Data System (ADS)

When implemented on the nanoscale, material flows driven by gradients in temperature, sometimes known as thermocapillary flows, can be exploited for various purposes, including nanopatterning, device fabrication, and purification of arrays of single walled carbon nanotubes (SWNTs). Systematic experimental and theoretical studies on thermocapillary flow in thin polymer films driven by heating in individual metallic SWNT over a range of conditions and molecular weights reveal the underlying physics of this process. The findings suggest that the zero-shear viscosity is a critical parameter that dominates the dependence on substrate temperature and heating power. The experimentally validated analytical models in this study allow assessment of sensitivity to other parameters, such as the temperature coefficient of surface tension, the thermal interface conductance, and the characteristic length scale of the heated zone.

Hun Jin, Sung; Song, Jizhou; Uk Chung, Ha; Zhang, Chenxi; Dunham, Simon N.; Xie, Xu; Du, Frank; Kim, Tae-il; Lee, Jong-Ho; Huang, Yonggang; Rogers, John A.

2014-02-01

306

Nanoscale electron-beam-stimulated processing  

NASA Astrophysics Data System (ADS)

Electron-beam-stimulated deposition and etching has been investigated as a clean, alternative method for nanoscale selective processing. Depositions using W(CO)6 and hydrocarbon sources have yielded efficient and selective electron-beam deposits. Primarily fluorine-based precursors have been used to etch a variety of materials. Initial results regarding the selective etching of silicon and silicon dioxide suggest that inelastic scattering of the primary electron beam with the gas occurs and is more severe at lower beam energies. The etch rate increases linearly with decreasing electron-beam energy, however, it is not clear if this is due to enhanced primary- or secondary-electron-stimulated processes. Feature sizes as small as 55 nm have been selectively processed.

Rack, P. D.; Randolph, S.; Deng, Y.; Fowlkes, J.; Choi, Y.; Joy, D. C.

2003-04-01

307

Probing absolute spin polarization at the nanoscale.  

PubMed

Probing absolute values of spin polarization at the nanoscale offers insight into the fundamental mechanisms of spin-dependent transport. Employing the Zeeman splitting in superconducting tips (Meservey-Tedrow-Fulde effect), we introduce a novel spin-polarized scanning tunneling microscopy that combines the probing capability of the absolute values of spin polarization with precise control at the atomic scale. We utilize our novel approach to measure the locally resolved spin polarization of magnetic Co nanoislands on Cu(111). We find that the spin polarization is enhanced by 65% when increasing the width of the tunnel barrier by only 2.3 Å due to the different decay of the electron orbitals into vacuum. PMID:25423049

Eltschka, Matthias; Jäck, Berthold; Assig, Maximilian; Kondrashov, Oleg V; Skvortsov, Mikhail A; Etzkorn, Markus; Ast, Christian R; Kern, Klaus

2014-12-10

308

Nanoscale characterization of engineered cementitious composites (ECC)  

SciTech Connect

Engineered cementitious composites (ECC) are ultra-ductile fiber-reinforced cementitious composites. The nanoscale chemical and mechanical properties of three ECC formulae (one standard formula, and two containing nanomaterial additives) were studied using nanoindentation, electron microscopy, and energy dispersive spectroscopy. Nanoindentation results highlight the difference in modulus between bulk matrix ({approx} 30 GPa) and matrix/fiber interfacial transition zones as well as between matrix and unreacted fly ash ({approx} 20 GPa). The addition of carbon black or carbon nanotubes produced little variation in moduli when compared to standard M45-ECC. The indents were observed by electron microscopy; no trace of the carbon black particles could be found, but nanotubes, including nanotubes bridging cracks, were easily located in ultrafine cracks near PVA fibers. Elemental analysis failed to show a correlation between modulus and chemical composition, implying that factors such as porosity have more of an effect on mechanical properties than elemental composition.

Sakulich, Aaron Richard, E-mail: asakulic@umich.edu; Li, Victor C.

2011-02-15

309

Carbon-bearing fluids at nanoscale interfaces  

SciTech Connect

The behaviour of fluids at mineral surfaces or in confined geometries (pores, fractures) typically differs from their bulk behaviour in many ways due to the effects of large internal surfaces and geometrical confinement. We summarize research performed on C-O-H fluids at nanoscale interfaces in materials of interest to the earth and material sciences (e.g., silica, alumina, zeolites, clays, rocks, etc.), emphasizing those techniques that assess microstructural modification and/or dynamical behaviour such as gravimetric analysis, small-angle (SANS) neutron scattering, and nuclear magnetic resonance (NMR). Molecular dynamics (MD) simulations will be described that provide atomistic characterization of interfacial and confined fluid behaviour as well as aid in the interpretation of the neutron scattering results.

Cole, David [Ohio State University; Ok, Salim [Ohio State University, Columbus; Phan, A [Ohio State University, Columbus; Rother, Gernot [ORNL; Striolo, Alberto [Oklahoma University; Vlcek, Lukas [ORNL

2013-01-01

310

Exploring Transport Effects in Nanoscale Graphene Devices  

NASA Astrophysics Data System (ADS)

Graphene, the single- to few-atomic layers cousin to graphite, has become a very interesting topic of research owing to its unique mechanical, optical, thermal and electrical properties. Many of the properties of graphene can be traced to its structural uniformity, allowing both electrons and holes to travel long distances (up to several microns) before scattering. However, studying graphene on the micron level can mask its true nanoscale behavior. Using very short length scales allows for the investigation of the behavior of charge impurities, contact effects and ballistic transport. In this work, we fabricate sub-30 nanometer suspended graphene 3-terminal devices on gold and platinum electrodes. We present data from electrical measurements on charge impurities that are apparent at this length scale and the effect of electrode work function on contact resistance. We compare this to mechanically exfoliated graphene on a silicon/SiO2 substrate with gold electrodes.

Worne, Jeff; Galande, Charudatta; Gullapalli, Hemtej; Ajayan, Pulickel; Natelson, Douglas

2011-03-01

311

Nanoscale confinement of all-optical switching in TbFeCo using plasmonic antennas  

E-print Network

All-optical switching (AOS) of magnetic domains by femtosecond laser pulses was first observed in the transition metal-rare earth (TM-RE) alloy GdFeCo1-5; this phenomenon demonstrated the potential for optical control of magnetism for the development of ever faster future magnetic recording technologies. The technological potential of AOS has recently increased due to the discovery of the same effect in other materials, including RE-free magnetic multilayers6,7. However, to be technologically meaningful, AOS must compete with the bit densities of conventional storage devices, restricting optically-switched magnetic areas to sizes well below the diffraction limit. Here, we demonstrate reproducible and robust all-optical switching of magnetic domains of 53 nm size in a ferrimagnetic TbFeCo alloy using gold plasmonic antenna structures. The confined nanoscale magnetic reversal is imaged around and beneath plasmonic antennas using x-ray resonant holographic imaging. Our results demonstrate the potential of future...

Liu, TianMin; Reid, Alexander H; Savoini, Matteo; Wu, Xiaofei; Koene, Benny; Granitzka, Patrick; Graves, Catherine; Higley, Daniel; Chen, Zhao; Razinskas, Gary; Hantschmann, Markus; Scherz, Andreas; Stöhr, Joachim; Tsukamoto, Arata; Hecht, Bert; Kimel, Alexey V; Kirilyuk, Andrei; Rasing, Theo; Dürr, Hermann A

2014-01-01

312

Effect of ion structure on nanoscale friction in protic ionic liquids.  

PubMed

The effect of ionic liquid (IL) molecular structure on nanoscale friction has been investigated using colloidal probe Friction Force Microscopy (FFM). The ILs studied were ethylammonium formate (EAF), ethylammonium nitrate (EAN), propylammonium formate (PAF), propylammonium nitrate (PAN), dimethylethylammonium formate (DMEAF), and ethanolammonium nitrate (EtAN). ILs were confined between a silica colloid probe and a mica surface, and the friction force was measured as a function of normal load for sliding velocities between 10 and 40 ?m s(-1). At low normal forces, multiple IL layers are found between the probe and the surface, but at higher force, in the boundary layer regime, a single ion layer separates the probe and the surface. In the boundary layer regime energy is dissipated by two main pathways. Firstly, the ionic liquid near the surface, with the exception of the boundary layer, is expelled from the advancing contact made by the probe on the surface. This disruption in the interactions between the boundary layer and the near surface multilayers, leads to energy dissipation and depends on the strength of the attraction between the boundary and near surface layers. The second pathway is via rotations and twists of ions in the boundary layer, primarily associated with the cation terminal methyl group. The friction coefficient did not vary over the limited range of sliding speeds investigated. PMID:24992959

Sweeney, James; Webber, Grant B; Rutland, Mark W; Atkin, Rob

2014-08-21

313

Nanoscale phase separation in coated Ag nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper we report the structural investigation of cysteine and glutathione capped Ag nanoparticles (NPs) by means of transmission electron microscopy (TEM), synchrotron X-ray diffraction (XRD) and pair distribution function (PDF) analysis. The combined use of these probes allowed us to observe the presence of two crystal structures in the coated AgNPs, i.e., the cubic and the hexagonal crystal structures of Ag. In particular, it was possible to demonstrate that the coated AgNPs are a nanoscale phase separated system where the two phases coexist within the single grain. In addition, the relative bulk amount of the fcc and hcp phases has been estimated and a possible correlation with the capping agent proposed.In this paper we report the structural investigation of cysteine and glutathione capped Ag nanoparticles (NPs) by means of transmission electron microscopy (TEM), synchrotron X-ray diffraction (XRD) and pair distribution function (PDF) analysis. The combined use of these probes allowed us to observe the presence of two crystal structures in the coated AgNPs, i.e., the cubic and the hexagonal crystal structures of Ag. In particular, it was possible to demonstrate that the coated AgNPs are a nanoscale phase separated system where the two phases coexist within the single grain. In addition, the relative bulk amount of the fcc and hcp phases has been estimated and a possible correlation with the capping agent proposed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10832h

Diaz-Fernandez, Yuri Antonio; Pallavicini, Piersandro; Pasotti, Luca; Milanese, Chiara; Pellicer, Eva; Baró, Maria D.; Ren, Yang; Malavasi, Lorenzo

2011-10-01

314

Multiple wavelength photolithography for preparing multilayer microstructures  

DOEpatents

The invention relates to a multilayer microstructure and a method for preparing thereof. The method involves first applying a first photodefinable composition having a first exposure wavelength on a substrate to form a first polymeric layer. A portion of the first photodefinable composition is then exposed to electromagnetic radiation of the first exposure wavelength to form a first pattern in the first polymeric layer. After exposing the first polymeric layer, a second photodefinable composition having a second exposure wavelength is applied on the first polymeric layer to form a second polymeric layer. A portion of the second photodefinable composition is then exposed to electromagnetic radiation of the second exposure wavelength to form a second pattern in the second polymeric layer. In addition, a portion of each layer is removed according to the patterns to form a multilayer microstructure having a cavity having a shape that corresponds to the portions removed.

Dentinger, Paul Michael (Livermore, CA); Krafcik, Karen Lee (Livermore, CA)

2003-06-24

315

Deconvolution of mixed magnetism in multilayer graphene  

SciTech Connect

Magnetic properties of graphite modified at the edges by KCl and exfoliated graphite in the form of twisted multilayered graphene (<4 layers) are analyzed to understand the evolution of magnetic behavior in the absence of any magnetic impurities. The mixed magnetism in multilayer graphene is deconvoluted using Low field-high field hysteresis loops at different temperatures. In addition to temperature and the applied magnetic field, the density of edge state spins and the interaction between them decides the nature of the magnetic state. By virtue of magnetometry and electron spin resonance studies, we demonstrate that ferromagnetism is intrinsic and is due to the interactions among various paramagnetic centers. The strength of these magnetic correlations can be controlled by modifying the structure.

Swain, Akshaya Kumar [IITB-Monash Research Academy, Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400076 (India); Bahadur, Dhirendra, E-mail: dhirenb@iitb.ac.in [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400076 (India)

2014-06-16

316

Functionalized multilayered graphene platform for urea sensor.  

PubMed

Multilayered graphene (MLG) is an interesting material for electrochemical sensing and biosensing because of its very large 2D electrical conductivity and large surface area. We propose a less toxic, reproducible, and easy method for producing functionalized multilayer graphene from multiwalled carbon nanotubes (MWCNTs) in mass scale using only concentrated H(2)SO(4)/HNO(3). Electron microscopy results show the MLG formation, whereas FTIR and XPS data suggest its carboxylic and hydroxyl-functionalized nature. We utilize this functionalized MLG for the fabrication of a novel amperometric urea biosensor. This biosensor shows linearity of 10-100 mg dL(-1), sensitivity of 5.43 ?A mg(-1) dL cm(-2), lower detection limit of 3.9 mg dL(-1), and response time of 10 s. Our results suggest that MLG is a promising material for electrochemical biosensing applications. PMID:22117758

Srivastava, Rajesh K; Srivastava, Saurabh; Narayanan, Tharangattu N; Mahlotra, Bansi D; Vajtai, Robert; Ajayan, Pulickel M; Srivastava, Anchal

2012-01-24

317

Multi-layer waste containment barrier  

DOEpatents

An apparatus for constructing an underground containment barrier for containing an in-situ portion of earth. The apparatus includes an excavating device for simultaneously (i) excavating earthen material from beside the in-situ portion of earth without removing the in-situ portion and thereby forming an open side trench defined by opposing earthen sidewalls, and (ii) excavating earthen material from beneath the in-situ portion of earth without removing the in-situ portion and thereby forming a generally horizontal underground trench beneath the in-situ portion defined by opposing earthen sidewalls. The apparatus further includes a barrier-forming device attached to the excavating device for simultaneously forming a side barrier within the open trench and a generally horizontal, multi-layer barrier within the generally horizontal trench. The multi-layer barrier includes at least a first layer and a second layer.

Smith, Ann Marie (Pocatello, ID); Gardner, Bradley M. (Idaho Falls, ID); Nickelson, David F. (Idaho Falls, ID)

1999-01-01

318

Multilayered (Hg,Cd)Te infrared detector  

NASA Technical Reports Server (NTRS)

Multilayered mercury-cadmium telluride photoconductive detectors were developed which are capable of providing individual coverage of three separate spectral wavelength bands without the use of beam splitters. The multilayered "three-color" detector on a single dewar takes the place of three separate detector/filter/dewar units and enables simpler and more reliable mechanical and optical designs for multispectral scanners and radiometers. Wavelength channel design goals (in micrometers) were: 10.1 to 11.0, 11.0 to 12.0, and 13.0. Detectivity for all channels was 1 x 10 to the 10th power cm-Hz 1/2/Watt. A problem occurred in finding an epoxy layer which had good infrared transmission properties and which also was chemically and mechanically compatible with HgCdTe processing techniques. Data on 6 candidate bonding materials are surveyed and discussed.

Rae, W. G.

1977-01-01

319

Normal incidence multilayer mirrors for extreme ultraviolet astronomy  

NASA Technical Reports Server (NTRS)

Sputtered multilayer coatings allow the use of normal incidence optics in the extreme ultraviolet (EUV) region below 500 A. Multilayer mirrors can be tailored to provide images at strong EUV lines in the sun and stars, in many cases making more efficient use of the telescope aperture than grazing incidence optics. Alternatively, the bandpass can be broadened at the expense of peak effective area, by varying the multilayer structure over the mirror surface. Such mirrors can also serve as optical elements in spectrographs for investigation of specific emission and absorption line complexes, and are self-filtering in that they reject nearby geocoronal and cosmic resonance line backgrounds. Current efforts at the Lockheed Palo Alto Research Laboratory in the design, fabrication, and testing of EUV multilayer mirrors are discussed. This program includes the design and fabrication of normal incidence EUV multilayer mirrors, and the deposition of multilayers on lacquer-coated substrates.

Stern, R. A.; Haisch, B. M.; Joki, E. G.; Catura, R. C.

1984-01-01

320

Staggered broad-band reflecting multilayers.  

PubMed

Considerable broadening of the reflectance band of a multilayer stack may be obtained by staggering the layer thicknesses in such a way that they form either an arithmetic or geometric progression. Results are shown for asymmetric and symmetric filters of 15, 25, and 35 layers. The presence of the narrowband transmission peaks exhibited by the symmetric filters is explained, and the advantages of the use of this type of filter as an interference filter is discussed. PMID:20048855

Heavens, O S; Liddell, H M

1966-03-01

321

Adsorption of ammonia on multilayer iron phthalocyanine  

SciTech Connect

The adsorption of ammonia on multilayers of well-ordered, flat-lying iron phthalocyanine (FePc) molecules on a Au(111) support was investigated by x-ray photoelectron spectroscopy. We find that the electron-donating ammonia molecules coordinate to the metal centers of iron phthlalocyanine. The coordination of ammonia induces changes of the electronic structure of the iron phthalocyanine layer, which, in particular, lead to a modification of the FePc valence electron spin.

Isvoranu, Cristina; Knudsen, Jan; Ataman, Evren; Andersen, Jesper N.; Schnadt, Joachim [Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00 Lund (Sweden); Schulte, Karina [MAX-lab, Lund University, Box 118, 221 00 Lund (Sweden); Wang Bin; Bocquet, Marie-Laure [Laboratoire de chimie, Ecole normale superieure de Lyon, 46, Allee d'Italie, 69364 Lyon Cedex 07 (France)

2011-03-21

322

Response time for multilayered platinum resistance thermometers  

NASA Technical Reports Server (NTRS)

Response time constants for several multilayered temperature transducers were determined numerically by using Martin Marietta's MITAS software package which is available at NASA Langley Research Center. Present results were found in close agreement with the solutions reported in the literature, thus, the capability of MITAS was justified. On the basis of experiences gained, the MITAS is recommended for use in predicting the response time constants of sensors by an in-situ technique.

Pandey, D. K.; Ash, R. L.

1985-01-01

323

Modeling of multilayer thin film recording media  

Microsoft Academic Search

A previously developed micromagnetic model for single-layer thin-film recording media is extended to model multilayer thin-film media. Effects of the magnetostatic interactions between the adjacent magnetic layers in the film are studied for a film with two magnetic layers separated by an ideal nonmagnetic layer. Magnetization reversal processes and hysteresis properties are studied for films with different separation layer thicknesses.

Jian-Gang Zhu

1992-01-01

324

Apparent Thermal Conductivity Of Multilayer Insulation  

NASA Technical Reports Server (NTRS)

Mathematical model of apparent or effective thermal conductivity between two successive layers of multilayer thermal insulation (MLI) offers potential for optimizing performance of insulation. One gains understanding of how each physical mechanism contributes to overall flow of heat through MLI blanket. Model helps analyze engineering tradeoffs among such parameters as number of layers, thicknesses of gaps between layers, types of spacers placed in gaps, weight, overall thickness, and effects of foregoing on apparent thermal conductivity through blanket.

Mcintosh, Glen E.

1995-01-01

325

Resonant Raman spectroscopy of twisted multilayer graphene  

NASA Astrophysics Data System (ADS)

Graphene and other two-dimensional crystals can be combined to form various hybrids and heterostructures, creating materials on demand with properties determined by the interlayer interaction. This is the case even for a single material, where multilayer stacks with different relative orientation have different optical and electronic properties. Probing and understanding the interface coupling is thus of primary importance for fundamental science and applications. Here we study twisted multilayer graphene flakes with multi-wavelength Raman spectroscopy. We find a significant intensity enhancement of the interlayer coupling modes (C peaks) due to resonance with new optically allowed electronic transitions, determined by the relative orientation of the layers. The interlayer coupling results in a Davydov splitting of the C peak in systems consisting of two equivalent graphene multilayers. This allows us to directly quantify the interlayer interaction, which is much smaller compared with Bernal-stacked interfaces. This paves the way to the use of Raman spectroscopy to uncover the interface coupling of two-dimensional hybrids and heterostructures.

Wu, Jiang-Bin; Zhang, Xin; Ijäs, Mari; Han, Wen-Peng; Qiao, Xiao-Fen; Li, Xiao-Li; Jiang, De-Sheng; Ferrari, Andrea C.; Tan, Ping-Heng

2014-11-01

326

Ultrasonic wave propagation in multilayered piezoelectric substrates  

SciTech Connect

Due to the increasing demand for higher operating frequency, lower attenuation, and stronger piezoelectricity, use of the layered structure has become necessary. Theoretical studies are carried out for ultrasonic waves propagating in the multilayered piezoelectric substrates. Each layer processes up to as low as monoclinic symmetry with various thickness and orientation. A plane acoustic wave is assumed to be incident, at varied frequency and incidence angle, from a fluid upon a multilayered substrate. Simple analytical expressions for the reflection and transmission coefficients are derived from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the multilayered piezoelectric substrates. Solutions are obtained for the individual layers which relate the field variables at the upper layer surfaces. The response of the total system proceeds by satisfying appropriate interfacial conditions across the layers. Based on the boundary conditions, two cases, {open_quotes}shorted{close_quotes} and {open_quotes}free{close_quotes}, are derived from which a so-called piezoelectric coupling factor is calculated to show the piezoelectric efficiency. Our results are rather general and show that the phase velocity is a function of frequency, layer thickness, and orientation.

Chien, H.T.; Sheen, S.H.; Raptis, A.C.

1994-04-11

327

Automation Enhancement of Multilayer Laue Lenses  

SciTech Connect

X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

Lauer K. R.; Conley R.

2010-12-01

328

Excitation of a Magnetic Multilayer by an Electric Current  

Microsoft Academic Search

We describe variations in the resistance of Co\\/Cu multilayers, induced by means of a high current density ~108 A\\/cm2 injected into the multilayer through a point contact. We propose that the observed resistance changes are due to excitations of zero-wave-number spin waves in the magnetic layers. As predicted, such current-driven excitation of a magnetic multilayer occurs for only one direction

M. Tsoi; A. G. M. Jansen; J. Bass; W.-C. Chiang; M. Seck; V. Tsoi; P. Wyder

1998-01-01

329

Nanometric chromium\\/chromium carbide multilayers for tribological applications  

Microsoft Academic Search

Metal\\/ceramic multilayers with periods in the nanometric range have been proposed as protective coatings due to their improved tribological and mechanical properties as compared to single coatings. We have evaluated nanometric chromium\\/chromium carbide (Cr\\/CrC) multilayers as a promising combination for tribological applications. These multilayers were synthesized by r.f. magnetron sputtering from a pure chromium target onto steel and silicon substrates.

J Romero; A Lousa; E Mart??nez; J Esteve

2003-01-01

330

Highly reflecting Y\\/Mg–H x multilayered switchable mirrors  

Microsoft Academic Search

Optical, structural and thermodynamic properties of Y\\/Mg–Hx multilayered switchable mirrors are investigated and compared with YMgHx-alloys and pure YHx. Multilayers clearly have superior reflectance in the low-hydrogen state over the whole range of photon energies, 0.72multilayers with the same overall composition is shifted in

I. A. M. E. Giebels; J. Isidorsson; E. S. Kooij; A. Remhof; N. J. Koeman; J. H. Rector; A. T. M van Gogh; R. Griessen

2002-01-01

331

Normal incidence multilayer mirrors for extreme ultraviolet astronomy.  

NASA Astrophysics Data System (ADS)

Sputtered multilayer coatings allow the use of normal incidence optics in the extreme ultraviolet (EUV) region below 500 Å. Multilayer mirrors can be tailored to provide images at strong EUV lines in the sun and stars, in many cases making more efficient use of the telescope aperture than grazing incidence optics. Current efforts in the design, fabrication, and testing of EUV multilayer mirrors are discussed.

Stern, R. A.; Haisch, B. M.; Joki, E. G.; Catura, R. C.

1984-01-01

332

76 FR 30656 - Multilayered Wood Flooring From the People's Republic of China: Preliminary Determination of...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...preliminarily determines that multilayered wood flooring from the People's Republic of...petition concerning imports of multilayered wood flooring from the PRC filed in proper...

2011-05-26

333

76 FR 76693 - Multilayered Wood Flooring From the People's Republic of China: Countervailing Duty Order  

Federal Register 2010, 2011, 2012, 2013

...Administration [C-570-971] Multilayered Wood Flooring From the People's Republic of...duty (``CVD'') order on multilayered wood flooring from the People's Republic of...producers and exporters of multilayered wood flooring from the PRC. See...

2011-12-08

334

75 FR 70714 - Multilayered Wood Flooring From the People's Republic of China: Initiation of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...petition concerning imports of multilayered wood flooring from the People's Republic of...and Countervailing Duties: Multilayered Wood Flooring from the People's Republic...

2010-11-18

335

76 FR 13357 - Multilayered Wood Flooring from the People's Republic of China: Postponement of Preliminary...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-970] Multilayered Wood Flooring from the People's Republic of...antidumping duty investigation on multilayered wood flooring from the People's Republic of...1\\ See Multilayered Wood Flooring from the People's Republic...

2011-03-11

336

78 FR 32367 - Multilayered Wood Flooring From the People's Republic of China; Preliminary Results of...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...antidumping duty order on multilayered wood flooring (``MLWF'') from the People's...Duty New Shipper Review: Multilayered Wood Flooring from the People's Republic...

2013-05-30

337

76 FR 19034 - Multilayered Wood Flooring From the People's Republic of China: Preliminary Affirmative...  

Federal Register 2010, 2011, 2012, 2013

...Administration [C-570-971] Multilayered Wood Flooring From the People's Republic of...producers and exporters of multilayered wood flooring from the People's Republic of...the Federal Register. See Multilayered Wood Flooring from the People's Republic...

2011-04-06

338

76 FR 92 - Multilayered Wood Flooring From the People's Republic of China: Postponement of Preliminary...  

Federal Register 2010, 2011, 2012, 2013

...Administration [C-570-971] Multilayered Wood Flooring From the People's Republic of...initiated an investigation of multilayered wood flooring from the People's Republic of China (``PRC''). See Multilayered Wood Flooring From the People's Republic...

2011-01-03

339

77 FR 45336 - Multilayered Wood Flooring From the People's Republic of China: Initiation of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...antidumping duty order on multilayered wood flooring from the People's Republic of...antidumping duty order on multilayered wood flooring from the PRC was published...

2012-07-31

340

78 FR 46318 - Multilayered Wood Flooring From the People's Republic of China: Initiation of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...antidumping duty order on multilayered wood flooring from the People's Republic of...antidumping duty order on multilayered wood flooring from the PRC on December 8,...

2013-07-31

341

Design and implementation of nanoscale fiber mechanical testing apparatus  

E-print Network

The rapid growth in the synthetic manufacturing industry demands higher resolution mechanical testing devices, capable of working with nanoscale fibers. A new device has been developed to perform single-axis tensile tests ...

Brayanov, Jordan, 1981-

2004-01-01

342

Nanoscale structure and transport : from atoms to devices  

E-print Network

Nanoscale structures present both unique physics and unique theoretical challenges. Atomic-scale simulations can find novel nanostructures with desirable properties, but the search can be difficult if the wide range of ...

Evans, Matthew Hiram

2005-01-01

343

Trapping and Manipulation of Isolated Atoms Using Nanoscale Plasmonic Structures  

E-print Network

We propose and analyze a scheme to interface individual neutral atoms with nanoscale solid-state systems. The interface is enabled by optically trapping the atom via the strong near-field generated by a sharp metallic ...

Chang, D. E.

344

Nanoscale reinforcement of polyhedral oligomeric silsesquioxane (POSS) in  

E-print Network

Nanoscale reinforcement of polyhedral oligomeric silsesquioxane (POSS) in polyurethane elastomer Valley, CA 92708-6117, USA Abstract: A unique class of polyurethane (PU) elastomer containing inorganic: polyhedral oligomeric silsesquioxane; POSS; polyurethane; nanocomposites; WAXD; SAXS; microphase separation

Mather, Patrick T.

345

Nanoscale magnetic sensing using spin qubits in diamond  

E-print Network

The ability to sense nanotelsa magnetic fields with nanoscale spatial resolution is an outstanding technical challenge relevant to the physical and biological sciences. For example, detection of such weak localized fields ...

Maze, J. R.

346

Nanoscale strength distribution in amorphous versus crystalline metals  

E-print Network

Low-load nanoindentation can be used to assess not only the plastic yield point, but the distribution of yield points in a material. This paper reviews measurements of the so-called nanoscale strength distribution (NSD) ...

Packard, C.E.

347

Negative pressure characteristics of an evaporating meniscus at nanoscale  

E-print Network

This study aims at understanding the characteristics of negative liquid pressures at the nanoscale using molecular dynamics simulation. A nano-meniscus is formed by placing liquid argon on a platinum wall between two ...

Maroo, Shalabh C.

2011-01-01

348

Modeling, identification, and application of multilayer polypyrrole conducting polymer actuators  

E-print Network

Experiments were performed using commercially available, self-contained, multilayer polypyrrole (PPy) actuators to develop low-order lumped parameter models of actuator electrical, mechanical, and electromechanical behavior. ...

Secord, Thomas W. (Thomas William)

2007-01-01

349

Microstructural Characterisation of Giant Magnetoresistive Co/Cu Multilayers  

SciTech Connect

Antiferromagnetically-coupled Co/Cu multilayers prepared by magnetron sputtering exhibit pronounced giant magnetoresistance (GMR) effect at room temperature. Using both diffraction and imaging techniques, we studied the in-plane and out-of-plane crystallographic and layering microstructural features of these multilayers. Dominant characteristic features associated with the multilayers, such as lateral and vertical columnar grain orientations as well as layer undulations and regularity, were identified. By deliberately introducing microstructural changes to the materials system using buffer layer and heat treatment, detailed microstructural analysis have provided an insight into the dependence of GMR on microstructures of the multilayers.

Kok, K. Y.; Ng, I. K. [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

2010-03-11

350

Stable Storage of Helium in Nanoscale Platelets at Semicoherent Interfaces  

NASA Astrophysics Data System (ADS)

He implanted into metals precipitates into nanoscale bubbles that may later grow into voids, degrading the properties of engineering alloys. Using multiscale modeling, we show that a different class of He precipitates may form at semicoherent interfaces: nanoscale platelets. These platelets grow by wetting high-energy interface regions, remain stable under irradiation, and reduce He-induced swelling. Stable storage of He at interfaces may impart unprecedented He resistance to future structural materials.

Kashinath, A.; Misra, A.; Demkowicz, M. J.

2013-02-01

351

The development, characterization, and application of biomimetic nanoscale enzyme immobilization  

NASA Astrophysics Data System (ADS)

The utilization of enzymes is of interest for applications such as biosensors and biofuel cells. Immobilizing enzymes provides a means to develop these applications. Previous immobilization efforts have been accomplished by exposing surfaces on which silica-forming molecules are present to solutions containing an enzyme and a silica precursor. This approach leads to the enzyme being entrapped in a matrix three orders of magnitude larger than the enzyme itself, resulting in low retention of enzyme activity. The research herein introduces a method for the immobilization of enzymes during the layer-by-layer buildup of Si-O and Ti-O coatings which are nanoscale in thickness. This approach is an application of a peptide-induced mineral deposition method developed in the Sandhage and Kroger groups, and it involves the alternating exposure of a surface to solutions containing the peptide protamine and then an aqueous precursor solution of silicon- or titanium-oxide at near-neutral pH. A method has been developed that enables in situ immobilization of enzymes in the protamine/mineral oxide coatings. Depending on the layer and mineral (silica or titania) within which the enzyme is incorporated, the resulting multilayer biocatalytic hybrid materials retain 20 -- 100% of the enzyme activity. Analyses of kinetic properties of the immobilized enzyme, coupled with characterization of physical properties of the mineral-bearing layers (thickness, porosity, pore size distribution), indicates that the catalytic activities of the enzymes immobilized in the different layers are largely determined by substrate diffusion. The enzyme was also found to be substantially stabilized against heat-induced denaturation and largely protected from proteolytic attack. These functional coatings are then developed for use as antimicrobial materials. Glucose oxidase, which catalyzes production of the cytotoxic agent hydrogen peroxide, was immobilized with silver nanoparticles, can release antimicrobial silver ions. It is demonstrated that these two antimicrobial agents work in a synergistic manner for enhanced antimicrobial efficacy. Evidence of the proposed mechanism of synergy, namely enhanced release of silver ions by reaction of H2O2 with silver nanoparticles, is provided. Finally, the deployment of these materials in silk fibroins for development as wound dressings is also presented. Protamine cross-linking was then extended to the oxygen-reducing enzyme laccase to explore the use of this modified enzyme in an enzymatic biocathode. In this application laccase accepts electrons from the electrode and uses them to reduce oxygen to water molecules. The protamine-cross-linked enzyme exhibits a higher degree of immobilization, better retention of activity once immobilized, and superior electrochemical activity versus the native enzyme. Finally, preliminary research on the structure-function relationships of 16-mer peptides which adsorb to surfaces and deposit titanium oxide is presented. Specifically, the effect of content and distribution of arginine residues on the ability of peptides to adsorb to surfaces and subsequently deposit mineral oxides was investigated. The data demonstrate that surface adsorption of the peptides relies on both a critical number of arginine residues and their position within the peptide. Furthermore, the exchange of serine against arginine residues in surface-adsorbed peptides is detrimental to Ti-O deposition.

Haase, Nicholas R.

352

Nanoscale tissue engineering: spatial control over cell-materials interactions  

PubMed Central

Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness the interactions through nanoscale biomaterials engineering in order to study and direct cellular behaviors. Here, we review the nanoscale tissue engineering technologies for both two- and three-dimensional studies (2- and 3D), and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffolds technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D, however, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and the temporal changes in cellular microenvironment. PMID:21451238

Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G.; Jabbari, Esmaiel; Khademhosseini, Ali

2011-01-01

353

Self-propagating reactions in Al/Zr multilayers: Anomalous dependence of reaction velocity on bilayer thickness  

NASA Astrophysics Data System (ADS)

High temperature, self-propagating reactions are observed in vapor-deposited Al/Zr multilayered foils of overall atomic ratios 3 Al:1 Zr and 2 Al:1 Zr and nanoscale layer thicknesses; however, the reaction velocities do not exhibit the inverse dependence on bilayer thickness that is expected based on changes in the average diffusion distance. Instead, for bilayer thicknesses of 20-30 nm, the velocity is essentially constant at ˜7.7 m/s. We explore several possible explanations for this anomalous behavior, including microstructural factors, changes in the phase evolution, and phase transformations in the reactant layers, but find no conclusive explanations. We determine that the phase evolution during self-propagating reactions in foils with a 3 Al:1 Zr stoichiometry is a rapid transformation from Al/Zr multilayers to the equilibrium intermetallic Al3Zr compound with no intermediate crystalline phases. This phase evolution is the same for foils of 90 nm bilayer thicknesses and foils of bilayer thicknesses in the range of 27 nm to 35 nm. Further, for foils with a bilayer thickness of 90 nm and a 3 Al:1 Zr overall chemistry, the propagation front is planar and steady, in contrast to unsteady reaction fronts in foils with 1 Al:1 Zr overall chemistry and similar bilayer thicknesses.

Barron, S. C.; Kelly, S. T.; Kirchhoff, J.; Knepper, R.; Fisher, K.; Livi, K. J. T.; Dufresne, E. M.; Fezzaa, K.; Barbee, T. W.; Hufnagel, T. C.; Weihs, T. P.

2013-12-01

354

Effect of electroless nickel interlayer on wear behavior of CrN/ZrN multilayer films on Cu-alloyed ductile iron  

NASA Astrophysics Data System (ADS)

This study utilized electroless nickel as an interlayer, then coated nanoscale CrN/ZrN multilayer on Cu-alloyed ductile iron through cathodic arc deposition method. Morphology and structure of the coatings were analyzed by using field emission scanning electron microscopy (FESEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). Moreover, Rockwell-C indentation, nanoindention, and ball-on-disk wear tests were all carried out to explore the properties of the coatings consisting of adhesion, hardness, elastic modulus, friction coefficient, and wear rate, respectively. The results showed that electroless nickel had a major amorphous phase while the CrN/ZrN multilayer coatings exhibited alternate nanocrystalline CrN and ZrN phases. Compared with single coating of electroless nickel or CrN/ZrN, the CrN/ZrN multilayer coatings with an electroless nickel interlayer exhibited higher hardness (31.1 GPa) and elastic modulus (256.4 GPa). Consequently, the ductile iron with the duplex coatings could be available to reduce both the friction coefficient and wear rate.

Lin, Chung-Kwei; Hsu, Cheng-Hsun; Kung, Shu-Chi

2013-11-01

355

Magnetoresistive phenomena in nanoscale magnetic systems  

NASA Astrophysics Data System (ADS)

Nanomagnetic materials are playing an increasingly important role in modern technologies. A particular area of interest involves the interplay between magnetism and electric transport, i.e. magnetoresistive properties. Future generations of field sensors and memory elements will have to be on a length scale of a few nanometers or smaller. Magnetoresistive properties of such nanoscale objects exhibit novel features due to reduced dimensionality, complex surfaces and interfaces, and quantum effects. In this dissertation theoretical aspects of three such nanoscale magnetoresistive phenomena are discussed. Very narrow magnetic domain walls can strongly scatter electrons leading to an increased resistance. Specifically, this dissertation will cover the newly predicted effect of magnetic moment softening in magnetic nanocontacts or nanowires. Atomically thin domain walls in Ni exhibit a reduction, or softening, of the local magnetic moments due to the noncollinearity of the magnetization. This effect leads to a strong enhancement of the resistance of a domain wall. Magnetic tunnel junctions (MTJs) consist of two ferromagnetic electrodes separated by a thin layer of insulating material through which current can be carried by electron tunneling. The resistance of an MTJ depends on the relative orientation of the magnetization of the two ferromagnetic layers, an effect known as tunneling magnetoresistance (TMR). A first-principles analysis of CoFeB|MgO|CoFeB MTJs will be presented. Calculations reveal that it is energetically favorable for interstitial boron atoms to reside at the interface between the electrode and MgO tunneling barrier, which can be detrimental to the TMR effect. Anisotropic magnetoresistance (AMR) is the change in resistance of a ferromagnetic system as the orientation of the magnetization is altered. In this dissertation, the focus will be on AMR in the tunneling regime. Specifically we will present new theoretical results on tunneling AMR (TAMR) in two systems: (i) planar MTJs with CoFe electrodes and (ii) fully broken magnetic break junctions. In both cases electronic resonances in the electrodes lead to complex angular and bias dependence of the TAMR. The theoretical studies demonstrate the basic physical phenomenon behind recent experimental data.

Burton, John D.

356

Magnetic properties of nanoscale iron particles  

NASA Astrophysics Data System (ADS)

Nanoscale iron particles have been prepared by iron atom clustering in cold pentane. Particle growth was terminated by adsorption of oleic acid, yielding air stable particles ranging in size from 2 to 12 nm, that were amorphous according to XRD analysis. TEM analysis showed that the larger particles were prolate spheroids while the smaller ones were spherical. The as-prepared sample had a room-temperature saturation magnetization of Ms=12.3 emu/g and a coercivity of Hc=60 Oe. Following heat treatment under argon, the XRD results showed the following reaction scheme; oxidation to Fe3O4 at 360 °C and reduction to ?-Fe at 520 °C (processes apparently due to adsorbed oleic acid). For the 520 °C treated sample, the room-temperature saturation magnetization and coercivity were Ms=200 emu/g and Hc=20 Oe, respectively. By pentane washing of the as-prepared sample, the smaller particles could be separated by filtration leaving the larger 8-12 nm particles on the filter. This powdered sample trapped on the filter had Ms=54.9 emu/g and Hc=60 Oe. Heat treatment of this sample also caused oxidation to Fe3O4 at 360 °C and an incomplete reduction to ?-Fe and FeO at 520 °C. For the 520 °C treated sample, the recorded room-temperature saturation magnetization and coercivity were Ms=123.6 emu/g and Hc=20 Oe, respectively.

Kerznizan, Carl F.; Klabunde, Kenneth J.; Sorensen, Christopher M.; Hadjipanayis, George C.

1990-05-01

357

Non-Equilibrium Nanoscale Self-Organization  

SciTech Connect

Self-organized one- and two-dimensional arrays of nanoscale surface features ("ripples" and "dots") sometimes form spontaneously on initially flat surfaces eroded by a directed ion beam in a process called "sputter patterning". Experiments on this sputter patterning process with focused and unfocused ion beams, combined with theoretical advances, have been responsible for a number of scientific advances. Particularly noteworthy are (i) the discovery of propagative, rather than dissipative, behavior under some ion erosion conditions, permitting a pattern to be fabricated at a large length scale and propagated over large distances while maintaining, or even sharpening, the sharpest features; (ii) the first demonstration of guided self-organization of sputter patterns, along with the observation that defect density is minimized when the spacing between boundaries is near an integer times the natural spatial period; and (iii) the discovery of metastability of smooth surfaces, which contradicts the nearly universally accepted linear stability theory that predicts that any surface is linearly unstable to sinusoidal perturbations of some wave vector.

Aziz, Michael J

2006-03-09

358

Surface Effects on Nanoscale Gas Flows  

NASA Astrophysics Data System (ADS)

3D MD simulations of linear Couette flow of argon gas confined within nano-scale channels are performed in the slip, transition and free molecular flow regimes. The velocity and density profiles show deviations from the kinetic theory based predictions in the near wall region that typically extends three molecular diameters (s) from each surface. Utilizing the Irwin-Kirkwood theorem, stress tensor components for argon gas confined in nano-channels are investigated. Outside the 3s region, three normal stress components are identical, and equal to pressure predicted using the ideal gas law, while the shear stress is a constant. Within the 3s region, the normal stresses become anisotropic and the shear stress shows deviations from its bulk value due to the surface virial effects. Utilizing the kinetic theory and MD predicted shear stress values, the tangential momentum accommodation coefficient for argon gas interacting with FCC structured walls (100) plane facing the fluid is calculated to be 0.75; this value is independent of the Knudsen number. Results show emergence of the 3s region as an additional characteristic length scale in nano-confined gas flows.

Beskok, Ali; Barisik, Murat

2010-11-01

359

Nanoscale glucan polymer network causes pathogen resistance  

PubMed Central

Successful defence of plants against colonisation by fungal pathogens depends on the ability to prevent initial penetration of the plant cell wall. Here we report that the pathogen-induced (1,3)-?-glucan cell wall polymer callose, which is deposited at sites of attempted penetration, directly interacts with the most prominent cell wall polymer, the (1,4)-?-glucan cellulose, to form a three-dimensional network at sites of attempted fungal penetration. Localisation microscopy, a super-resolution microscopy technique based on the precise localisation of single fluorescent molecules, facilitated discrimination between single polymer fibrils in this network. Overexpression of the pathogen-induced callose synthase PMR4 in the model plant Arabidopsis thaliana not only enlarged focal callose deposition and polymer network formation but also resulted in the exposition of a callose layer on the surface of the pre-existing cellulosic cell wall facing the invading pathogen. The importance of this previously unknown polymeric defence network is to prevent cell wall hydrolysis and penetration by the fungus. We anticipate our study to promote nanoscale analysis of plant-microbe interactions with a special focus on polymer rearrangements in and at the cell wall. Moreover, the general applicability of localisation microscopy in visualising polymers beyond plant research will help elucidate their biological function in complex networks. PMID:24561766

Eggert, Dennis; Naumann, Marcel; Reimer, Rudolph; Voigt, Christian A.

2014-01-01

360

Exploring fault rocks at the nanoscale  

NASA Astrophysics Data System (ADS)

This paper aims to demonstrate the potential role of micro/nanoscale investigations in the study of fault rocks, given that a multiscale and multidisciplinary approach linking structural geology, petrology and mineralogy from the outcrop to the unit-cell scale is essential to the comprehensive characterization of geological materials. To explore fault rocks at the sub-micrometer scale, a fundamental contribution is provided by the Transmission Electron Microscope (TEM), which offers a real-time combination of high-resolution images, diffraction patterns, and chemical data for extremely small volumes, providing accurate mineralogical and nanostructural determinations. This paper focuses on a few selected examples, that are particularly appropriate for TEM investigation, in particular: 1) grain-size determinations on ultrafine-grained fault rocks; 2) detection and characterization of poorly crystalline minerals (e.g., clays) and amorphous phases within fault rocks; 3) identification of deformation-induced mineral reactions occurring within fault zones (e.g., dolomite decarbonation and serpentine dehydration); and 4) observations of recurrent deformation nanotextures in phyllosilicates. TEM investigation can provide an unexpected amount of data, much of which cannot be obtained by conventional techniques, and it can therefore significantly contribute to an understanding of the physico-chemical conditions for faulting and fault mechanics.

Viti, Cecilia

2011-12-01

361

Sulfidation of Cadmium at the Nanoscale  

SciTech Connect

We investigate the evolution of structures that result when spherical Cd nanoparticles of a few hundred nanometers in diameter react with dissolved molecular sulfur species in solution to form hollow CdS. Over a wide range of temperatures and concentrations, we find that rapid Cd diffusion through the growing CdS shell localizes the reaction front at the outermost CdS/S interface, leading to hollow particles when all the Cd is consumed. When we examine partially reacted particles, we find that this system differs significantly from others in which the nanoscale Kirkendall effect has been used to create hollow particles. In previously reported systems, partial reaction creates a hollow particle with a spherically symmetric metal core connected to the outer shell by filaments. In contrast, here we obtain a lower symmetry structure, in which the unreacted metal core and the coalesced vacancies separate into two distinct spherical caps, minimizing the metal/void interface. This pattern of void coalescence is likely to occur in situations where the metal/vacancy self-diffusivities in the core are greater than the diffusivity of the cations through the shell.

Cabot, Andreu; Smith, Rachel; Yin, Yadong; Zheng, Haimei; Reinhard, Bjorn; Liu, Haitao; Alivisatos, A. Paul

2008-05-22

362

Nanoscale Thermal Transport in Graphene Interfaces  

NASA Astrophysics Data System (ADS)

We have investigated nanoscale thermal transport in epitaxial graphene systems using first-principles calculations and the Landauer formalism for phonon transport. Two types of interfaces are investigated: graphene-dielectric and graphene-metal heterojunctions. Hexagonal boron nitride (h-BN), SiC and SiC with hydrogen passivation (SiC-H) are studied as potential dielectric substrate materials for graphene devices. As for graphene-metal contacts, we have considered Au and Ti as prototypical systems for physisorbed and chemisorbed metal contacts, respectively. The interfacial thermal resistances of h-BN/G system is 5.3 10-9 Km^2/W at room temperature, which is approximately one order of magnitude smaller than that of SiC/G system (55-79 10-9 Km^2/W). Further analysis shows that heat conduction at the graphene interfaces is dominated by low-lying acoustic phonons and the thermal resistances strongly depend on atomic details at the interface such as lattice mismatch, disorder and surface reconstruction. Our work demonstrates the importance of developing a microscopic description of phonon dynamics at heterogeneous interfaces to engineer and design devices with optimal thermal management.

Mao, Rui; Kong, Byoungdon; Jayasekera, Thushari; Buongiorno-Nardelli, Marco; Kim, Ki Wook

2012-02-01

363

Dynamics of nanoscale droplets on moving surfaces.  

PubMed

We use molecular dynamics (MD) simulations to investigate the dynamic wetting of nanoscale water droplets on moving surfaces. The density and hydrogen bonding profiles along the direction normal to the surface are reported, and the width of the water depletion layer is evaluated first for droplets on three different static surfaces: silicon, graphite, and a fictitious superhydrophobic surface. The advancing and receding contact angles, and contact angle hysteresis, are then measured as a function of capillary number on smooth moving silicon and graphite surfaces. Our results for the silicon surface show that molecular displacements at the contact line are influenced greatly by interactions with the solid surface and partly by viscous dissipation effects induced through the movement of the surface. For the graphite surface, however, both the advancing and receding contact angles values are close to the static contact angle value and are independent of the capillary number; i.e., viscous dissipation effects are negligible. This finding is in contrast with the wetting dynamics of macroscale water droplets, which show significant dependence on the capillary number. PMID:23683083

Ritos, Konstantinos; Dongari, Nishanth; Borg, Matthew K; Zhang, Yonghao; Reese, Jason M

2013-06-11

364

Nanoscale platinum printing on insulating substrates.  

PubMed

The deposition of noble metals on soft and/or flexible substrates is vital for several emerging applications including flexible electronics and the fabrication of soft bionic implants. In this paper, we describe a new strategy for the deposition of platinum electrodes on a range of materials, including insulators and flexible polymers. The strategy is enabled by two principle advances: (1) the introduction of a novel, low temperature strategy for reducing chloroplatinic acid to platinum using nitrogen plasma; (2) the development of a chloroplatinic acid based liquid ink formulation, utilizing ethylene glycol as both ink carrier and reducing agent, for versatile printing at nanoscale resolution using dip-pen nanolithography (DPN). The ink formulation has been printed and reduced upon Si, glass, ITO, Ge, PDMS, and Parylene C. The plasma treatment effects reduction of the precursor patterns in situ without subjecting the substrate to destructively high temperatures. Feature size is controlled via dwell time and degree of ink loading, and platinum features with 60 nm dimensions could be routinely achieved on Si. Reduction of the ink to platinum was confirmed by energy dispersive x-ray spectroscopy (EDS) elemental analysis and x-ray diffraction (XRD) measurements. Feature morphology was characterized by optical microscopy, SEM and AFM. The high electrochemical activity of individually printed Pt features was characterized using scanning electrochemical microscopy (SECM). PMID:24270681

O'Connell, C D; Higgins, M J; Sullivan, R P; Jamali, S S; Moulton, S E; Wallace, G G

2013-12-20

365

QUANTITATIVE CHARACTERIZATION AND EVOLUTION OF NANOSCALE POROSITY Tao Sun, S. Donthu, Arvind Srivastava, Jin Wang, and Vinayak P. Dravid  

E-print Network

18 QUANTITATIVE CHARACTERIZATION AND EVOLUTION OF NANOSCALE POROSITY Tao Sun, S. Donthu, Arvind Nanoscale Science & Engineering Center (NUNSEC) Award Number: EEC ­ 0647560 Nanoscale porosity, ranging from catalysis to gas storage to sensing devices. Since porosity represents "missing

Shull, Kenneth R.

366

Normal incidence multilayer mirrors for extreme ultraviolet astronomy  

Microsoft Academic Search

Sputtered multilayer coatings allow the use of normal incidence optics in the extreme ultraviolet (EUV) region below 500 Å. Multilayer mirrors can be tailored to provide images at strong EUV lines in the sun and stars, in many cases making more efficient use of the telescope aperture than grazing incidence optics. Current efforts in the design, fabrication, and testing of

R. A. Stern; B. M. Haisch; E. G. Joki; R. C. Catura

1984-01-01

367

Power bus decoupling on multilayer printed circuit boards  

Microsoft Academic Search

Guidelines for the selection and placement of decoupling capacitors that work well for one-sided or two-sided printed circuit boards are not appropriate for multilayer boards with power and ground planes. Boards without internal planes take advantage of the power bus inductance to help decouple components at the higher frequencies. An effective decoupling strategy for multilayer boards must account for the

Todd H. Hubing; James L. Drewniak; Thomas P. Van Doren; David M. Hockanson

1995-01-01

368

Inspection of multilayer components by the neutron backscattering method  

SciTech Connect

The results of calculations and experimental examination of neutron backscattering (albedo) from multilayer components are examined. The results of calculations and experimental determination of sensitivity in thickness gauging of multilayer components are presented and the optimum conditions of inspection in the conditions with one-side access are determined.

Pekarskii, G.Sh.

1987-07-01

369

PC software for SAW propagation in anisotropic multilayers  

Microsoft Academic Search

A software package that provides an interactive and graphical environment for surface acoustic wave (SAW) and plate-mode propagation studies in arbitrarily oriented anisotropic and piezoelectric multilayers is described. The software, which runs on an IBM PC with math coprocessor, is based on a transfer-matrix formulation for calculating the characteristics of SAW propagation in multilayers that was originally written for a

E. L. Adler; J. K. Slaboszewicz; G. W. Farnell; C. K. Jen

1990-01-01

370

A MULTILAYER BIOCHEMICAL DRY DEPOSITION MODEL 1. MODEL FORMULATION  

EPA Science Inventory

A multilayer biochemical dry deposition model has been developed based on the NOAA Multilayer Model (MLM) to study gaseous exchanges between the soil, plants, and the atmosphere. Most of the parameterizations and submodels have been updated or replaced. The numerical integration ...

371

Room Temperature Metastability of Multilayer Graphene Oxide Films  

E-print Network

Room Temperature Metastability of Multilayer Graphene Oxide Films Suenne Kim1 , Si Zhou2 , Yike Hu1 oxide has multiple potential applications. The chemistry of graphene oxide and its response to external experimental and density functional theory study shows that multilayer graphene oxide produced by oxidizing

Paris-Sud XI, Université de

372

Prediction of Multilayer Printed Wiring Board Temperatures During Lamination  

Microsoft Academic Search

Measurements of temperature histories of epoxy\\/glass prepreg layers during multilayer printed wiring board lamination have been recently obtained. It is shown that the temperature histories may be predicted by an analysis of the transient heat flow process within the multilayer board (MLB). The analysis requires a knowledge of the press platen temperature history during laminations and the thermal resistance of

Win Aung

1975-01-01

373

Propagation of Acoustic Waves in Liquid Containing Multilayer Barrier  

NASA Astrophysics Data System (ADS)

The dynamics of acoustic waves in a liquid containing multilayer barrier is studied. Using the subroutine of the fast Fourier transform the calculation of the distortion of the acoustic signal at the diagnosis of a multilayer sample comprising a layer of a liquid with polydispersed bubbles is executed. A good agreement between theoretical and experimental data is obtained.

Gubaidullin, D. A.; Nikiforov, A. A.

2014-11-01

374

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS  

E-print Network

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS by David T. Oliphant. Woolley Dean, College of Physical and Mathematical Sciences #12;ABSTRACT CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS David T. Oliphant Department of Physics and Astronomy

Hart, Gus

375

Ultrathin self-assembled polyelectrolyte multilayer membranes  

NASA Astrophysics Data System (ADS)

The paper is concerned with ultrathin membranes prepared upon alternating layer-by-layer adsorption of cationic and anionic polyelectrolytes on a porous substructure. The formation of the polyelectrolyte multilayer membranes is characterised and the transport of gases, liquid mixtures and ions across the membranes is studied. In particular, the use of the membranes for alcohol/water separation under pervaporation conditions, and for the separation of mono- and divalent ions is described. It is demonstrated that upon a suitable choice of polyelectrolytes and substructures, and a careful optimisation of preparation and operation conditions, membranes can be tailored exhibiting an excellent separation capability.

Tieke, B.; van Ackern, F.; Krasemann, L.; Toutianoush, A.

376

Multilayer insulation considerations for large propellant tanks  

NASA Astrophysics Data System (ADS)

Multilayer insulation (MLI) systems for cryogenic instrument Dewars have demonstrated very high thermal performance in ground and orbit. Ground tests of insulation systems on propellant storage size tanks have shown performance and repeatability issues. This paper presents a summary of studies for National Aeronautics and Space Administration (NASA) focused on MLI systems on the larger Tankage. The sensitivity of boil off to MLI thermal conductivity is presented. The effect of compressions, assembly joints and MLI parameters are presented. A novel large tank simulator approach for MLI testing is presented along with recommendations for maturation of the MLI technology.

Nast, T. C.; Frank, D. J.; Feller, J.

2014-11-01

377

Coherent thermal conductance in multilayer photonic crystals  

E-print Network

We present an exact calculation of the coherent thermal conductance in a 1-D multilayer photonic crystals (PC) using the S-matrix method. In particular, we study the thermal conductance in a bilayer structure of slabs of Si/vacuum or Al$_2$O$_3$/vacuum by means of the exact expression for the radiative heat flux. We compare our results with results obtained in previous works. Our results show that the coupling of surface modes as well as material losses play a fundamental role in the definition of the thermal conductance of PCs.

Maria Tschikin; Philippe Ben-Abdallah; Svend-Age Biehs

2012-06-25

378

Engineering aspects of multilayer piezoceramic actuators  

NASA Astrophysics Data System (ADS)

With the increasing demand for multilayer ceramic chip components a full understanding of the co-firing of ceramics with metal electrodes becomes important. In the present work the processing of a piezoelectric monolithic actuator by stacking and cofiring Ag-Pd electroded tape cast layers was studied. The inter-diffusion and microstructure of the co-fired interface of PZT ferroelectrics and Ag-Pd metal electrode were examined by scanning electron microscopy (SEM) and energy-dispersive microanalysis. No strong structural distortions and interdiffusion were observed at the co-fired ceramic-electrode interface.

Golovnin, V. A.; Kaplunov, I. A.; Ivanova, A. I.; Grechishkin, R. M.

2013-12-01

379

Performance of multilayer insulation with slotted shield  

NASA Astrophysics Data System (ADS)

Thermal and evacuating performance can be improved by means of slotting a number of one dimension slots on reflection shields of the multilayer insulation (MLI). The influence of slots on thermal radiation and gas conduction heat fluxes are theoretically studied. Based on the analysis and test, the optimum slot rate and length have been obtained. Experiments also show that the performance of MLI with slotted shield will be further improved if a combination of slotted shields with different slot rate can be used to fit the interstitial pressure distribution.

Chen, Guobang; Sun, Tao; Zheng, Jianyao; Huang, Zhixue; Yu, Jianping

380

Thin film photovoltaic device with multilayer substrate  

DOEpatents

A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

Catalano, Anthony W. (Rushland, PA); Bhushan, Manjul (Wilmington, DE)

1984-01-01

381

Layer-resolved conductivities in multilayer graphene  

NASA Astrophysics Data System (ADS)

We study interlayer transport of multilayer graphenes in a magnetic field with various stacking structures (AB, ABC, and AA types) by calculating the Hall and longitudinal conductivities as functions of the Fermi energy. Their behavior depends strongly on the stacking structures and selection of the layers. The Hall conductivity between different layers is no longer quantized. Moreover, for AB stacking, the interlayer conductivity vanishes around zero energy with increasing layer separation, and shows negative values in particular cases. The fact that longitudinal interlayer conductivity is suppressed by a magnetic field indicates that this system can be applied as a switching device.

Wakutsu, Takeo; Nakamura, Masaaki; Dóra, Balázs

2012-01-01

382

Polarization laminated cartography of multilayer biological tissues  

NASA Astrophysics Data System (ADS)

This paper was considered the possibility of phase imaging optical anisotropic multilayer biological structures. Was founded a principle of superposition of polarization displays optical anisotropy of polycrystalline protein networks. The optical model of polycrystalline networks of biological tissues protein fibrils is presented. The technique of phase tomography based on determining the coordinate distributions of Mueller-matrix elements of biological tissues is suggested. The results of investigating the interrelation between the values of statistical (statistical moments of the 1st-4thorder) parameters are presented. They characterize the coordinate distributions of phase shifts of biological tissue layer of different optical thickness and the degree of muscle dystrophy.

Zabolotna, N. I.

2012-01-01

383

Improved multilayer insulation applications. [spacecraft thermal control  

NASA Technical Reports Server (NTRS)

Multilayer insulation blankets used for the attenuation of radiant heat transfer in spacecraft are addressed. Typically, blanket effectiveness is degraded by heat leaks in the joints between adjacent blankets and by heat leaks caused by the blanket fastener system. An approach to blanket design based upon modular sub-blankets with distributed seams and upon an associated fastener system that practically eliminates the through-the-blanket conductive path is described. Test results are discussed providing confirmation of the approach. The specific case of the thermal control system for the optical assembly of the Space Telescope is examined.

Mikk, G.

1982-01-01

384

Manufacture and analysis of multilayer woven preforms  

SciTech Connect

Multilayer woven preforms were manufactured from high-tenacity, continuous multifilament polyester yarn and HTA carbon yarn. Orthogonal fiber architectures were constructed with a variety of binder thread configurations and yarn densities. The effect of the binder thread arrangement upon the as-woven preform architecture was examined. The preforms were then consolidated using liquid moulding techniques and the effect of the consolidation pressure upon the fiber architecture was investigated. Modeling of the preform architecture in its as-woven state is progressing and preliminary results are presented in this paper.

Bannister, M.K.; Herszberg, I.; Coman, F.; Raper, H.; Curiskis, J. [Royal Melbourne Institute of Technology (Australia)

1994-12-31

385

Multilayer insulation thermal protection systems technology  

NASA Technical Reports Server (NTRS)

A summary is presented of the work performed by Marshall Space Flight Center (MSFC) and industry toward the development of flight-type multilayer insulation(MLI) systems. The MSFC MLI program is divided into three large categories: (1) the generation and compilation of MLI composite test data; (2) the analysis, design, and testing of heat flow through MLI applied to ducting, seams, electrical feedthroughs, structural supports, and the tank sidewall; and (3) the development, modification, and utilization of new testing procedures, tanks, and the test facilities. Numerous data have been generated, analyzed, and documented on different MLI composites.

Hyde, E. H.

1971-01-01

386

Enhanced piezoelectric response in the artificial ferroelectric polymer multilayers  

NASA Astrophysics Data System (ADS)

An actuator with a high piezoelectric response, the ferroelectric polymer multilayer actuator, is described. The ferroelectric polymer multilayers consisting of alternative ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer and relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofloroethylene) (P(VDF-TrFE-CFE)) terpolymer with different periodicities and fixed total thickness are prepared by the Langmuir-Blodgett technique. Both X-ray diffraction and Raman spectroscopic measurements indicate that the structure of the multilayer with thin alternating layer is similar to that of the ferroelectric copolymer. Compared with that of the copolymer, it is found that the piezoelectric coefficient of the multilayer could be improved by 57%. We attributed the enhanced piezoelectric response of the multilayers to the internal electric fields that arises from the electrostatic couplings between different layers.

Zhao, X. L.; Wang, J. L.; Tian, B. B.; Liu, B. L.; Wang, X. D.; Sun, S.; Zou, Y. H.; Lin, T.; Sun, J. L.; Meng, X. J.; Chu, J. H.

2014-12-01

387

Crystallography of Co/Pt multilayers and nanostructures  

SciTech Connect

Atomically engineered nanostructures and multilayers of Co/Pt exhibit strong perpendicular anisotropy. This unique property, that determines their potential as a magneto-optic recording media, is dependent on a variety of microstructural parameters that include the overall crystallography, thickness of the layers, orientation, defect formation, interface reactions etc. A series of Co/Pt multilayer samples with different thickness of the Co layer were studied by electron diffraction. It has been determined that the Co layers persists in the fcc structure up to a thickness of 50 {Angstrom}. As the thickness is varied fmm 3{Angstrom} to 50{Angstrom} in the multilayers, the Co film gradually relaxed to its bulk lattice parameter. (111) twinning and lattice strain at the interfaces between Pt and Co layers are also observed. The symmetry forbidden reflections observed at 1/3 (224) positions in (111) zone diffraction patterns of the multilayer are due to (111) twinning and compositional modulations along the multilayer growth direction.

Zhang, Bing; Krishnan, K.M. [Lawrence Berkeley Lab., CA (United States); Farrow, R.F.C. [IBM Research Div., San Jose, CA (United States). Almaden Research Center

1992-04-01

388

Enhancing spontaneous emission rates of molecules using nanopatterned multilayer hyperbolic metamaterials  

NASA Astrophysics Data System (ADS)

Plasmonic nanostructures have been extensively used to manipulate the spontaneous light emission rate of molecules and their radiative efficiency. Because molecules near a metallic surface experience a different environment than in free space, their spontaneous radiative emission rate is generally enhanced. Such enhancement, measured by means of the Purcell factor, arises as a consequence of the overlap between the surface plasmon mode frequency and the emission spectrum of the molecule. However, such overlap is available only for a few narrow bands of frequency due to the limited plasmonic materials existing in nature. Although this limitation can be overcome by using hyperbolic metamaterials (HMMs)--a type of nanoscale artificial material with hyperbolic dispersion relations--the Purcell factor and the radiative power have remained relatively low. Here, we show that by nanopatterning a hyperbolic metamaterial made of Ag and Si multilayers, the spontaneous emission rate of rhodamine dye molecules is enhanced 76-fold at tunable frequencies and the emission intensity of the dye increases by ~80-fold compared with the same hyperbolic metamaterial without nanostructuring. We explain these results using a dynamic Lorentzian model in the time domain.

Lu, Dylan; Kan, Jimmy J.; Fullerton, Eric E.; Liu, Zhaowei

2014-01-01

389

In vitro studies on regulation of osteogenic activities by electrical stimulus on biodegradable electroactive polyelectrolyte multilayers.  

PubMed

In this study, a novel electroactive tetreaniline-containing degradable polyelectrolyte multilayer film (PEM) coating [(poly(l-glutamic acid)-graft-tetreaniline/poly(l-lysine)-graft-tetreaniline)n, (PGA-g-TA/PLL-g-TA)n] was designed and fabricated by layer-by-layer (LbL) assembly method. Compared with the nongrafted PEMs, the tetreaniline-grafted PEMs showed higher roughness and stiffness in micro/nanoscale structures. The special surface characteristics and the typical electroconductive properties were more beneficial for adhesion, proliferation, and differentiation of preosteoblast MC3T3-E1 cells. Moreover, the enhanced effects were observed on the modulation of MC3T3-E1 cells that differentiated into maturing osteoblasts, when the electroactive PEMs were coupled with electrical stimulus (ES), especially in the early phase of the osteoblast differentiation. The alkaline phosphatase (ALP) activity, calcium deposition, immunofluorescence staining, and RT-qPCR were evaluated on the differentiation of preosteoblast. These data indicate that the comprehensive effects through coupling electroactive scaffolds with electrical stimulus are better to develop bioelectric strategies to control cell functions for bone regeneration. PMID:24995801

Cui, Haitao; Wang, Yu; Cui, Liguo; Zhang, Peibiao; Wang, Xianhong; Wei, Yen; Chen, Xuesi

2014-08-11

390

Calcium Binding-Mediated Sustained Release of Minocycline from Hydrophilic Multilayer Coatings Targeting Infection and Inflammation  

PubMed Central

Infection and inflammation are common complications that seriously affect the functionality and longevity of implanted medical implants. Systemic administration of antibiotics and anti-inflammatory drugs often cannot achieve sufficient local concentration to be effective, and elicits serious side effects. Local delivery of therapeutics from drug-eluting coatings presents a promising solution. However, hydrophobic and thick coatings are commonly used to ensure sufficient drug loading and sustained release, which may limit tissue integration and tissue device communications. A calcium-mediated drug delivery mechanism was developed and characterized in this study. This novel mechanism allows controlled, sustained release of minocycline, an effective antibiotic and anti-inflammatory drug, from nanoscale thin hydrophilic polyelectrolyte multilayers for over 35 days at physiologically relevant concentrations. pH-responsive minocycline release was observed as the chelation between minocycline and Ca2+ is less stable at acidic pH, enabling ‘smart’ drug delivery in response to infection and/or inflammation-induced tissue acidosis. The release kinetics of minocycline can be controlled by varying initial loading, Ca2+ concentration, and Ca2+ incorporation into different layers, enabling facile development of implant coatings with versatile release kinetics. This drug delivery platform can potentially be used for releasing any drug that has high Ca2+ binding affinity, enabling its use in a variety of biomedical applications. PMID:24409292

Zhang, Zhiling; Nix, Camilla A.; Ercan, Utku K.; Gerstenhaber, Jonathan A.; Joshi, Suresh G.; Zhong, Yinghui

2014-01-01

391

Proof of Concept Thin Films and Multilayers Toward Enhanced Field Gradients in SRF Cavities  

SciTech Connect

Due to the very shallow penetration depth of the RF fields, SRF properties are inherently a surface phenomenon involving a material thickness of less than 1 micron thus opening up the possibility of using thin film coatings to achieve a desired performance. The challenge has been to understand the dependence of the SRF properties on the detailed characteristics of real surfaces and then to employ appropriate techniques to tailor these surface properties for greatest benefit. Our aim is to achieve gradients >100 MV/m and no simple material is known to be capable of sustaining this performance. A theoretical framework has been proposed which could yield such behavior [1] and it requires creation of thin film layered structures. I will present our systematic studies on such proof-of-principle samples. Our overarching goal has been to build a basic understanding of key nano-scale film growth parameters for materials that show promise for SRF cavity multilayer coatings and to demonstrate the ability to elevate the barrier for vortex entry in such layered structures above the bulk value of Hc1 for type-II superconductors and thus to sustain higher accelerating fields.

Lukaszew, R.A.; Beringer, D.; Roach, W.M.; Eremeev, G.V.; Valente-Feliciano, A-M.; Reece, C.E.; Xi, X.

2013-09-01

392

Dielectric structure pyrotechnic initiator realized by integrating Ti/CuO-based reactive multilayer films  

NASA Astrophysics Data System (ADS)

A dielectric structure pyrotechnic initiator was proposed and the initiator samples were designed and realized by integrating Ti/CuO-based reactive multilayer films on ceramic substrate. The dielectric structure consists of essentially two titanium films separated by a copper oxide (CuO) film, which is just like as a capacitor guaranteeing the initiator will not be discharged until the external voltage has exceeded the breakdown strength of the CuO film. Results of the electrical explosion experiment show that the breakdown strength of 1-?m-thick CuO film is 60 V, and the initiator has "late time discharge" characteristics, which will improve the conversion ratio of the electricity greatly, and there is a nanoscale exothermic reaction in the electrical explosion process. A systematic temperature measurement model based on the "double-line atomic emission spectroscopy of copper element" was presented and used to test the explosion temperature and duration. The ejected explosion flame was seen clearly with a potential temperature exceeding 4500 K for 0.1 ms, 4250 K for 0.35 ms, and 4000 K for 0.5 ms. Besides, electric energy and exothermic reaction create high-temperature products, which discharge to a distance of 1 cm or more. The high temperature and ejected products may be able to ignite the attached energetic materials even if the initiator makes no physical contact. These characteristics of the initiator may open a door to the preparation of the highly efficient and insensitive initiating explosive device.

Zhu, Peng; Shen, Ruiqi; Fiadosenka, N. N.; Ye, Yinghua; Hu, Yan

2011-04-01

393

Boundary integral spectral element method analyses of extreme ultraviolet multilayer defects.  

PubMed

Extreme ultraviolet (EUV) lithography is an emerging technology for high-density semiconductor patterning. Multilayer distortion caused by mask defects is regarded as one of the critical challenges of EUV lithography. To simulate the influence of the defected nanoscale structures with high accuracy and efficiency, we have developed a boundary integral spectral element method (BI-SEM) that combines the SEM with a set of surface integral equations. The SEM is used to solve the interior computational domain, while the open boundaries are truncated by the surface integral equations. Both two-dimensional (2D) and three-dimensional (3D) EUV cases are simulated. Through comparing the performance of this method with the conventional finite element method (FEM), it is shown that the proposed BI-SEM can greatly decrease both the memory cost and the computation time. For typical 2D problems, we show that the BI-SEM is 11 and 1.25 times more efficient than the FEM in terms of memory and CPU time, respectively, while for 3D problems, these factors are over 14 and 2, respectively, for smaller problems; realistic 3D problems that cannot be solved by the conventional FEM can be accurately simulated by the BI-SEM. PMID:25401246

Niu, Jun; Luo, Ma; Fang, Yuan; Liu, Qing Huo

2014-10-01

394

Dry etching technologies for reflective multilayer  

NASA Astrophysics Data System (ADS)

We have developed a highly integrated methodology for patterning Extreme Ultraviolet (EUV) mask, which has been highlighted for the lithography technique at the 14nm half-pitch generation and beyond. The EUV mask is characterized as a reflective-type mask which is completely different compared with conventional transparent-type of photo mask. And it requires not only patterning of absorber layer without damaging the underlying multi reflective layers (40 Si/Mo layers) but also etching multi reflective layers. In this case, the dry etch process has generally faced technical challenges such as the difficulties in CD control, etch damage to quartz substrate and low selectivity to the mask resist. Shibaura Mechatronics ARESTM mask etch system and its optimized etch process has already achieved the maximal etch performance at patterning two-layered absorber. And in this study, our process technologies of multi reflective layers will be evaluated by means of optimal combination of process gases and our optimized plasma produced by certain source power and bias power. When our ARES™ is used for multilayer etching, the user can choose to etch the absorber layer at the same time or etch only the multilayer.

Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Kase, Yoshihisa; Yoshimori, Tomoaki; Muto, Makoto; Nonaka, Mikio; Iwami, Munenori

2012-11-01

395

Development of Flexible Multilayer Circuits and Cables  

NASA Technical Reports Server (NTRS)

A continuing program addresses the development of flexible multilayer electronic circuits and associated flexible cables. This development is undertaken to help satisfy aerospace-system-engineering requirements for efficient, lightweight electrical and electronic subsystems that can fit within confined spaces, adhere to complexly shaped surfaces, and can be embedded within composite materials. Heretofore, substrate layers for commercial flexible circuitry have been made from sheets of Kapton (or equivalent) polyimide and have been bonded to copper conductors and to other substrate layers by means of adhesives. The substrates for the present developmental flexible circuitry are made from thin films of a polyimide known as LaRC(TM)-SI. This polyimide is thermoplastic and, therefore, offers the potential to eliminate delamination and the need for adhesives. The development work undertaken thus far includes experiments in the use of several techniques of design and fabrication (including computer-aided design and fabrication) of representative flexible circuits. Anticipated future efforts would focus on multilayer bonding, fabrication of prototypes, and overcoming limitations.

Barnes, Kevin N.; Bryant, Robert; Holloway, Nancy; Draughon, Fred

2005-01-01

396

Polymer multilayer tattooing for enhanced DNA vaccination  

PubMed Central

DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These “multilayer tattoo” DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination. PMID:23353628

DeMuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

2014-01-01

397

Diffusion of Polyelectrolyte Chains within Multilayer Films  

NASA Astrophysics Data System (ADS)

Using a series of polycations synthesized by atom transfer radical polymerization, we investigate the relative importance of the effects of hydrophobicity, polymer charge density, and steric hindrance to charge pairing on chain dynamics within polyelectrolyte complexes (PECs) and within polyelectrolyte multilayer (PEM) films. First, by applying fluorescence correlation spectroscopy (FCS), ellipsometry and fluorescence recovery after photobleaching (FRAP), we found that the dynamics of chain exchange within PECs is directly correlated with the mode (linear vs. exponential) of PEM film growth. Second, through a combination of neutron reflectometry (NR) and FRAP techniques to the same PEM types, we found that diffusion of polyelectrolyte chains within multilayer films is highly anisotropic, with diffusion coefficients being 10^4-10^5 higher in a direction parallel to the substrate compared to that perpendicular. Chain mobility was also controlled by ionic strength of annealing solutions and steric hindrance to ionic pairing of interacting polyelectrolytes.[4pt] This work was supported by the National Science Foundation under Award DMR-0906474 (S.S.). Neutron measurements were performed at the Spallation Neutron Source at the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the DOE under contract No. DE-AC05-00OR22725.

Sukhishvili, Svetlana; Xu, Li; Zhuk, Aliaksandr; Ankner, John

2012-02-01

398

Polymer multilayer tattooing for enhanced DNA vaccination  

NASA Astrophysics Data System (ADS)

DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These ‘multilayer tattoo’ DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination.

Demuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

2013-04-01

399

Finite element analysis of multilayer coextrusion.  

SciTech Connect

Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.

Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A. (Proctor & Gamble Company, West Chester, OH); Mrozek, Randy A. (Army Research Laboratory, Adelphi, MD); Lenhart, Joseph Ludlow (Army Research Laboratory, Adelphi, MD); Rao, Rekha Ranjana; Collins, Robert (Oak Ridge National Laboratory); Mondy, Lisa Ann

2011-09-01

400

Load responsive multilayer insulation performance testing  

SciTech Connect

Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.

Dye, S.; Kopelove, A. [Quest Thermal Group, 6452 Fig Street Suite A, Arvada, CO 80004 (United States); Mills, G. L. [Ball Aerospace and Technologies Corp, 1600 Commerce Street, Boulder, CO 80301 (United States)

2014-01-29

401

Temperature matching of multilayer insulation to penetrations  

NASA Astrophysics Data System (ADS)

To accurately predict the heat load into a cryogenic tank or cold mass which includes multilayer insulation (MLI), heat loads other than just through the pristine MLI must be accounted for. One such type of heat load is the integration of the MLI system around penetrations. While a number of different methods that have been developed, the ideal solution would be one in which there are zero thermal losses due to the integration. Theoretically, the be st method to achieving zero integration losses is to match the individual MLI temperature layers with the corresponding penetration location having the same temperature; this method is known as temperature matching. Recently, NASA has employed temperature matching integration of multilayer insulation systems onto several different cryogenic tanks with different structural elements and attachments. T esting included the Methane Lunar Surface Thermal Control testing at Glenn Research Center, the CRYOTE Ground Test Article testing at Marshall Space Flight Center, and the Penetration Calorimetery work done at Kennedy Space Center. Each test was instrumented to determine the effects of temperature matching within MLI and each system was designed in a different manner. The testing showed that temperature matching can indeed produce nearly zero thermal losses. However, our findings show that there are many practical limitations to this approach. Temperature matching integration schemes were found to be very sensitive to thermal environmental changes and even tank liquid level changes. The approach is therefore considered useful only for a select few cases and not useful for most engineering applications.

Johnson, W. L.; Plachta, D. W.; Rhys, N. O.; Kelly, A. O.

2014-01-01

402

Nanoscale Graphene Oxide (nGO) as Artificial Receptors: Implications for Biomolecular Interactions and Sensing  

E-print Network

Nanoscale Graphene Oxide (nGO) as Artificial Receptors: Implications for Biomolecular Interactions by using nanoscale GOs (nGO) as artificial receptors. Unlike conventional GO, nGOs are sheets with near

Huang, Jiaxing

403

Thermal contact resistance across nanoscale silicon dioxide and silicon Jie Chen, Gang Zhang, and Baowen Li  

E-print Network

Thermal contact resistance across nanoscale silicon dioxide and silicon interface Jie Chen, Gang://jap.aip.org/about/rights_and_permissions #12;Thermal contact resistance across nanoscale silicon dioxide and silicon interface Jie Chen,1 Gang

Li, Baowen

404

Enabling complex nanoscale pattern customization using directed self-assembly  

NASA Astrophysics Data System (ADS)

Block copolymer directed self-assembly is an attractive method to fabricate highly uniform nanoscale features for various technological applications, but the dense periodicity of block copolymer features limits the complexity of the resulting patterns and their potential utility. Therefore, customizability of nanoscale patterns has been a long-standing goal for using directed self-assembly in device fabrication. Here we show that a hybrid organic/inorganic chemical pattern serves as a guiding pattern for self-assembly as well as a self-aligned mask for pattern customization through cotransfer of aligned block copolymer features and an inorganic prepattern. As informed by a phenomenological model, deliberate process engineering is implemented to maintain global alignment of block copolymer features over arbitrarily shaped, ‘masking’ features incorporated into the chemical patterns. These hybrid chemical patterns with embedded customization information enable deterministic, complex two-dimensional nanoscale pattern customization through directed self-assembly.

Doerk, Gregory S.; Cheng, Joy Y.; Singh, Gurpreet; Rettner, Charles T.; Pitera, Jed W.; Balakrishnan, Srinivasan; Arellano, Noel; Sanders, Daniel P.

2014-12-01

405

Reduction of Thermal Conductivity by Nanoscale 3D Phononic Crystal  

PubMed Central

We studied how the period length and the mass ratio affect the thermal conductivity of isotopic nanoscale three-dimensional (3D) phononic crystal of Si. Simulation results by equilibrium molecular dynamics show isotopic nanoscale 3D phononic crystals can significantly reduce the thermal conductivity of bulk Si at high temperature (1000?K), which leads to a larger ZT than unity. The thermal conductivity decreases as the period length and mass ratio increases. The phonon dispersion curves show an obvious decrease of group velocities in 3D phononic crystals. The phonon's localization and band gap is also clearly observed in spectra of normalized inverse participation ratio in nanoscale 3D phononic crystal. PMID:23378898

Yang, Lina; Yang, Nuo; Li, Baowen

2013-01-01

406

Probing and tuning frictional aging at the nanoscale  

PubMed Central

Time-dependent increase of frictional strength, or frictional aging, is a widely observed phenomenon both at macro and nanoscales. The frictional aging at the nanoscale may result from nucleation of capillary bridges and strengthening of chemical bonding, and it imposes serious constraints and limitations on the performance and lifetime of micro- and nanomachines. Here, by analytical model and numerical simulations, we investigate the effect of inplane oscillations on friction in nanoscale contacts which exhibit aging. We demonstrate that adding a low amplitude oscillatory component to the pulling force, when applied at the right frequency, can significantly suppress aging processes and thereby reduce friction. The results obtained show that frictional measurements performed in this mode can provide significant information on the mechanism of frictional aging and stiffness of interfacial contacts. PMID:23719489

Capozza, Rosario; Barel, Itay; Urbakh, Michael

2013-01-01

407

Effect of nanoscale patterned interfacial roughness on interfacial toughness.  

SciTech Connect

The performance and the reliability of many devices are controlled by interfaces between thin films. In this study we investigated the use of patterned, nanoscale interfacial roughness as a way to increase the apparent interfacial toughness of brittle, thin-film material systems. The experimental portion of the study measured the interfacial toughness of a number of interfaces with nanoscale roughness. This included a silicon interface with a rectangular-toothed pattern of 60-nm wide by 90-nm deep channels fabricated using nanoimprint lithography techniques. Detailed finite element simulations were used to investigate the nature of interfacial crack growth when the interface is patterned. These simulations examined how geometric and material parameter choices affect the apparent toughness. Atomistic simulations were also performed with the aim of identifying possible modifications to the interfacial separation models currently used in nanoscale, finite element fracture analyses. The fundamental nature of atomistic traction separation for mixed mode loadings was investigated.

Zimmerman, Jonathan A.; Moody, Neville Reid; Mook, William M. (University of Minnesota, Minneapolis, MN); Kennedy, Marian S. (Clemson University, Clemson, SC); Bahr, David F. (Washington State University, Pullman, WA); Zhou, Xiao Wang; Reedy, Earl David, Jr.

2007-09-01

408

Flexible nanoscale high-performance FinFETs.  

PubMed

With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics. PMID:25185112

Torres Sevilla, Galo A; Ghoneim, Mohamed T; Fahad, Hossain; Rojas, Jhonathan P; Hussain, Aftab M; Hussain, Muhammad Mustafa

2014-10-28

409

Mechanical performance of foam glass with nanoscale structure elements  

NASA Astrophysics Data System (ADS)

The paper presents experimental data on studying the strengthening of glass foam material. Glass foam material is foamed glass of increased strength achieved due to nanoscale structural elements. Glass foam is obtained through thermal treatment of noncrystalline matrix containing crystalline material in the silica state. It is shown that strengthening of glass foam material is achieved by structuring the noncrystalline partition. New technique of strengthening is proposed due to the formation of nanoscale globules of noncrystalline matrix. Self-organization of spherical nanoscale globules. New technique for glass foam strengthening. For the first time the phenomenon of strengthening interpore partition of glass foam was established. The principle of the process consists in the formation of noncrystalline matrix with a specific globular structure.

Kazmina, O. V.; Semukhin, B. S.; Njuguna, J.

2012-09-01

410

Surface roughness analysis of multilayer x-ray optics  

NASA Astrophysics Data System (ADS)

Rigaku Innovative Technologies (RIT) produces x-ray optics based on multilayer mirrors. A multilayer mirror is deposited on a wafer and mounted on a solid backing plate in an elliptical shape to focus x-rays. The wafer surface imperfections, defects from the multilayer deposition, and figure errors induced by the mounting process result in some focal spot widening for the final optics. An AFM is used in the spatial period range 0.1 - 10 microns, and a "ZYGO" interferometric microscope is used in the spatial period range 1 micron - 5 mm, to study these imperfections determining the influence of each technological step on the focal spot quality. AFM analysis shows dramatically different roughness between 1 x 1 micron and 20 x 20 micron field of view on super-polished substrates from some suppliers and only a little difference from others. A smoothing effect of a multilayer coating at spatial periods less than one micron as well as defects in multilayer coatings have been observed with power spectral density analysis. Machining marks on the surface of wafers are clearly seen at ZYGO microscope pictures. Ray-tracing simulations based on the ZYGO data show the focal spot shape changes due to the figure errors introduced at the step of a multilayer coated wafer mounting and only background scattering with no focal spot widening from defects induced at the step of multilayer deposition.

Martynov, Vladimir V.; Platonov, Yuriy Y.

2008-08-01

411

Tuning the electrochemical swelling of polyelectrolyte multilayers toward nanoactuation.  

PubMed

We discuss physicochemical determinants of electrochemical polyelectrolyte multilayer swelling that are relevant to actuator usage. We used electrochemical quartz crystal microbalance with dissipation monitoring (EC-QCM-D) and cyclic voltammetry to compare the electrochemical swelling of two types of ferrocyanide-containing polyelectrolyte multilayers, poly(l-glutamic acid)/poly(allylamine hydrochloride) (PGA/PAH), and carboxymethyl cellulose/poly(diallyldimethylammonium chloride) (CMC/PDDA). We showed that ferrocyanide oxidation causes the swelling of PGA/PAH multilayers whereas it results in the contraction of CMC/PDDA multilayers. This behavior can be attributed to the presence of a positive and a negative Donnan potential in the case of PGA/PAH and CMC/PDDA multilayers, respectively. Using multilayers consisting of PGA and poly(allylamine) ferrocene (PGA/PAH-FC), we applied EC-QCM-D and demonstrated potentiostatic thickness control with nanometer precision and showed that the multilayer's thickness depends linearly on the applied potential within a certain potential range. PMID:25229875

Zahn, Raphael; Vörös, János; Zambelli, Tomaso

2014-10-14

412

Multilayer mirrors and filters for imaging the earth's inner magnetosphere  

SciTech Connect

The authors present guidelines for the performance of multilayer mirrors and filters for imaging the earth's inner magnetosphere by isolating the 304-A He[sup +]emission. The analysis shows that the combination of filters and multilayer mirrors for an inner magnetosphere imager must attenuate the 1226-A Lyman [alpha] emission by six orders of magnitude and the 584-, 834-, and 1026-A background emissions by three orders of magnitude relative to the 304-A signal. Multilayer mirrors with the highest possible reflectance at 304 A are needed to preserve as much of the low-intensity 304-A signal as possible. The design of multilayer mirrors is discussed, and the results of an exhaustive computer search for the best multilayer mirror design for 304-A radiation are presented and analyzed. The theoretical performance of these new multilayer mirror designs is significantly better than th of designs currently used for imaging the solar 304-A emission. Promising materials for normal-incidence multilayer mirrors for 304-A radiation are B[sub 4]C, Be, Si, or SiC used with Al, Mg, or Mg[sub 2]Si. Promising materials for a filter for this application are Te passivated with Si, or a combination of Al or Si with B or C.

Schulze, D.W. (Univ. of Arizona, Tucson, AZ (United States). Dept of Physics); Sandel, B.R.; Broadfoot, A.L. (Univ. of Arizona, Tucson, AZ (United States). Lunar and Planetary Lab.)

1993-01-01

413

Center for Nanoscale Materials User Access Program Overview CNM User Access Program Overview  

E-print Network

Center for Nanoscale Materials User Access Program Overview CNM User Access Program Overview 1 of the Center for Nanoscale Materials (CNM) user program is to provide the user community with access to equipment, facilities, and personnel that support CNM's overall focus on nanoscale materials. The CNM makes

Kemner, Ken

414

Communications to the Editor A Nano-Scale Barrel and Cube: Transition  

E-print Network

Communications to the Editor A Nano-Scale Barrel and Cube: Transition Metal-Mediated Self target assemblies. We detail below construction of a nanoscale barrel 1 and a nanoscale cube 2V. 1998, 27, 289. (2) Alternatively, self-assembly 2 can be construed as a truncated cube if one defines

Clemmer, David E.

415

Nanoscale design to enable the revolution in renewable energy Jason Baxter,a  

E-print Network

Nanoscale design to enable the revolution in renewable energy Jason Baxter,a Zhixi Bian,b Gang Chen, and conservation technologies specifically related to recent and prospective advances in nanoscale science technologies and identifying unique opportunities enabled by nanoscale design of materials, processes

416

Transient Simulations for Nano-scale Filament Stretching with Large Deformation-Rates  

E-print Network

1 Transient Simulations for Nano-scale Filament Stretching with Large Deformation-Rates K stretching, on the nano-scale and under very large deformation-rates. To compute transient free correction. Keyword: Finite Element Method, Filament Stretch, Nano-scale, Large Strain-Rates, Hencky

Grant, P. W.

417

A Look Inside Argonne's Center for Nanoscale Materials  

SciTech Connect

At a very small, or "nano" scale, materials behave differently. The study of nanomaterials is much more than miniaturization - scientists are discovering how changes in size change a material's properties. From sunscreen to computer memory, the applications of nanoscale materials research are all around us. Researchers at Argonne's Center for Nanoscale Materials are creating new materials, methods and technologies to address some of the world's greatest challenges in energy security, lightweight but durable materials, high-efficiency lighting, information storage, environmental stewardship and advanced medical devices.

Divan, Ralu; Rosenthal, Dan; Rose, Volker; Wai Hla, Saw; Liu, Yuzi

2014-01-29

418

Optical generation of intense ultrashort magnetic pulses at the nanoscale  

NASA Astrophysics Data System (ADS)

Generating, controlling and sensing strong magnetic fields at ever shorter time and length scales is important for both fundamental solid-state physics and technological applications such as magnetic data recording. Here, we propose a scheme for producing strong ultrashort magnetic pulses localized at the nanoscale. We show that a bimetallic nanoring illuminated by femtosecond laser pulses responds with transient thermoelectric currents of picosecond duration, which in turn induce Tesla-scale magnetic fields in the ring cavity. Our method provides a practical way of generating intense nanoscale magnetic fields with great potential for materials characterization, terahertz radiation generation and data storage applications.

Tsiatmas, Anagnostis; Atmatzakis, Evangelos; Papasimakis, Nikitas; Fedotov, Vassili; Luk'yanchuk, Boris; Zheludev, Nikolay I.; García de Abajo, F. Javier

2013-11-01

419

STRUCTURAL TRANSITIONS IN NANOPARTICLE ASSEMBLIES GOVERNED BY COMPETING NANOSCALE FORCES  

PubMed Central

Assembly of nanoscale materials from nanoparticle (NP) building blocks relies on our understanding of multiple nanoscale forces acting between NPs. These forces may compete with each other and yield distinct stimuli-responsive self-assembled nanostructures. Here, we report structural transitions between linear chains and globular assemblies of charged, polymer-stabilized gold NPs, which are governed by the competition of repulsive electrostatic forces and attractive poor solvency/hydrophobic forces. We propose a simple quantitative model and show that these transitions can be controlled by the quality of solvent, addition of a salt, and variation of the molecular weight of the polymer ligands. PMID:23806016

Choueiri, Rachelle; Klinkova, Anna; Thérien-Aubin, Heloise; Rubinstein, Michael; Kumacheva, Eugenia

2013-01-01

420

Cornell NanoScale Science and Technology Facility  

NSDL National Science Digital Library

The Cornell NanoScale Science & Technology Facility (CNF) is a national user facility that supports a broad range of nanoscale science and technology projects by providing state-of-the-art resources coupled with expert staff support. 2007 marks our 30th year in operation. Research at CNF encompasses physical sciences, engineering, and life sciences, and has a strong inter-disciplinary emphasis. Over 700 users per year (50% of whom come from outside Cornell) use the fabrication, synthesis, computation, characterization, and integration resources of CNF to build structures, devices, and systems from atomic to complex length-scales.

2008-11-20

421

Strategies for Controlled Placement of Nanoscale Building Blocks  

PubMed Central

The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others. PMID:21794185

2007-01-01

422

Self-assembly of novel lipid-mimicking brush polymers in nanoscale thin films.  

PubMed

A series of well-defined poly(oxy(11-phosphorylcholineundecylthiomethyl)ethylene-ran-oxy(n-dodecylthiomethyl)ethylene) (PECH-PCm: m = 0-100 mol% phosphorylcholine (PC)) polymers were used to prepare nanoscale thin films that were characterized by synchrotron X-ray reflectivity (XR) analysis. The quantitative XR analysis provided structural insights into the PECH-PCm thin films. The PECH-PC0 polymer film formed a well-ordered in-plane oriented molecular multibilayer structure, whose individual layers consisted of two sublayers. One sublayer was composed of the fully extended backbones and inner part of the bristles, exhibiting a relatively low electron density, whereas the other sublayer was composed of a bilayer of the outer parts of the bristles without interdigitation. The PECH-PC100 polymer film also formed a well-ordered in-plane oriented molecular multibilayer structure, the individual layers of which were composed of four sublayers rather than two. The bristles in the layer were interdigitated in part via the zwitterionic interactions of the PC end groups. Surprisingly, regardless of the copolymer composition, the PECH-PCm random copolymer molecules in the thin films self-assembled to form a multilayered structure that resembled the structure formed by the PECH-PC100 polymer. These properties have not been observed in other conventional random brush copolymer films. The remarkable multibilayer structures originated from the zwitterionic PC end groups and their favorable interactions and interdigitated structures, which overcame any negative contributions caused by the heterogeneity of the bristles. The unique self-assembly properties of the PECH-PCm polymers always provide a PC-rich surface. The PECH-PCm random copolymers successfully mimicked the molecular bilayer structures formed by natural lipids. PMID:24838200

Jung, Jungwoon; Kim, Heesoo; Ree, Moonhor

2014-02-01

423

Investigation of nanoscale reinforcement into textile polymers  

NASA Astrophysics Data System (ADS)

A dual inclusion strategy for textile polymers has been investigated to increase elastic energy storage capacity of fibers used in high velocity impact applications. Commercial fibers such as Spectra and Dyneema are made from ultra high molecular weight polyethylene (UHMWPE). Dynamic elastic energy of these fibers is still low therefore limiting their wholesale application without a secondary metallic or ceramic component. The idea in this investigation is to develop methodologies so that the elastic energy of polyethylene based fibers can be increased by several folds. This would allow manufacturing of an all-fabric system for high impact applications. The dual inclusion consists of a polymer phase and a nanoscale inorganic phase to polyethylene. The polymer phase was nylon-6 and the inorganic phase was carbon nanotubes (CNTs). Nylon-6 was blended as a minor phase into UHMWPE and was chosen because of its large fracture strain -- almost one order higher than that of UHMWPE. On the other hand, CNTs with their very high strength, modulus, and aspect ratio, contributed to sharing of load and sliding of polymer interfaces as they aligned during extrusion and strain hardening processes. A solution spinning process was developed to produce UHMWPE filaments reinforced with CNTs and nylon-6. The procedure involved dispersing of CNTs into paraffin oil through sonication followed by dissolving polymers into paraffin-CNT solution using a homogenizer. The admixture was fed into a single screw extruder for melt mixing and extrusion through an orifice. The extrudate was rinsed via a hexane bath, stabilized through a heater, and then drawn into a filament winder with controlled stretching. In the next step, the as produced filaments were strain-hardened through repeated loading unloading cycles under tension. Neat and reinforced filaments were characterized through DSC (Differential Scanning Calorimetry), XRD (X-ray Diffraction), Raman Spectroscopy, SEM (Scanning Electron Microscope), and mechanical tests. Phenomenal improvement in properties was found; modulus, strength, fracture strain, and elastic energy increased by 219%, 100%, 107%, and 88%, respectively before strain hardening. Once strain hardened the strength, modulus and elastic energy increased by almost one order of magnitude. Source of these improvements were traced to increase in crystallinity and rate of crystallization, formation of microdroplets as a minor phase, sliding between minor and major phases, coating of nanotubes with polymer and alignment of nanotubes.

Khan, Mujibur Rahman

424

Nanoscale coordination polymers for anticancer drug delivery  

NASA Astrophysics Data System (ADS)

This dissertation reports the synthesis and characterization of nanoscale coordination polymers (NCPs) for anticancer drug delivery. Nanoparticles have been explored in order to address the limitations of small molecule chemotherapeutics. NCPs have been investigated as drug delivery vehicles as they can exhibit the same beneficial properties as the bulk metal-organic frameworks as well as interesting characteristics that are unique to nanomaterials. Gd-MTX (MTX = methotrexate) NCPs with a MTX loading of 71.6 wt% were synthesized and stabilized by encapsulation within a lipid bilayer containing anisamide (AA), a small molecule that targets sigma receptors which are overexpressed in many cancer tissues. Functionalization with AA allows for targeted delivery and controlled release to cancer cells, as shown by enhanced efficacy against leukemia cells. The NCPs were doped with Ru(bpy)32+ (bpy = 2,2'-bipyridine), and this formulation was utilized as an optical imaging agent by confocal microscopy. NCPs containing the chemotherapeutic pemetrexed (PMX) were synthesized using different binding metals. Zr-based materials could not be stabilized by encapsulation with a lipid bilayer, and Gd-based materials showed that PMX had degraded during synthesis. However, Hf-based NCPs containing 19.7 wt% PMX were stabilized by a lipid coating and showed in vitro efficacy against non-small cell lung cancer (NSCLC) cell lines. Enhanced efficacy was observed for formulations containing AA. Additionally, NCP formulations containing the cisplatin prodrug disuccinatocisplatin were prepared; one of these formulations could be stabilized by encapsulation within a lipid layer. Coating with a lipid layer doped with AA rendered this formulation an active targeting agent. The resulting formulation proved more potent than free cisplatin in NSCLC cell lines. Improved NCP uptake was demonstrated by confocal microscopy and competitive binding assays. Finally, a Pt(IV) oxaliplatin prodrug was synthesized and incorporated in different NCPs using various binding metals. A moderate drug loading of 44.9 wt% was determined for Zr-based NCPs. This drug loading, along with a diameter less than 200 nm, make these particles promising candidates for further stabilization via lipid encapsulation.

Phillips, Rachel Huxford

425

Nanoscale phenomena in ferroelectric thin films  

NASA Astrophysics Data System (ADS)

Ferroelectric materials are a subject of intense research as potential candidates for applications in non-volatile ferroelectric random access memories (FeRAM), piezoelectric actuators, infrared detectors, optical switches and as high dielectric constant materials for dynamic random access memories (DRAMs). With current trends in miniaturization, it becomes important that the fundamental aspects of scaling of ferroelectric and piezoelectric properties in these devices be studied thoroughly and their impact on the device reliability assessed. In keeping with this spirit of miniaturization, the dissertation has two broad themes: (a) Scaling of ferroelectric and piezoelectric properties and (b) The key reliability issue of retention loss. The thesis begins with a look at results on scaling studies of focused-ion-beam milled submicron ferroelectric capacitors using a variety of scanning probe characterization tools. The technique of piezoresponse microscopy, which is rapidly becoming an accepted form of domain imaging in ferroelectrics, has been used in this work for another very important application: providing reliable, repeatable and quantitative numbers for the electromechanical properties of submicron structures milled in ferroelectric films. This marriage of FIB and SPM based characterization of electromechanical and electrical properties has proven unbeatable in the last few years to characterize nanostructures qualitatively and quantitatively. The second half of this dissertation focuses on polarization relaxation in FeRAMs. In an attempt to understand the nanoscale origins of back-switching of ferroelectric domains, the time dependent relaxation of remnant polarization in epitaxial lead zirconate titanate (PbZr0.2Ti0.8O 3, PZT) ferroelectric thin films (used as a model system), containing a uniform 2-dimensional grid of 90° domains (c-axis in the plane of the film) has been examined using voltage modulated scanning force microscopy. A novel approach of imaging domains with polarization within the plane of the film has been used in this work. Relaxation is seen to occur through the nucleation and growth of reverse domains, which subsequently coalesce and consume the reversed region as a function of time. Results on the effect of local curvature, faceting, and pinning of 180° domain walls on relaxation kinetics are presented. Following the experimental observations, a model for the growth of the reversed domains has been formulated based on the thermo-activated overcoming of pinning sites in these materials. (Abstract shortened by UMI.)

Ganpule, Chandan S.

426

Brownian thermal noise in multilayer coated mirrors  

NASA Astrophysics Data System (ADS)

We analyze the Brownian thermal noise of a multilayer dielectric coating used in high-precision optical measurements, including interferometric gravitational-wave detectors. We assume the coating material to be isotropic, and therefore study thermal noises arising from shear and bulk losses of the coating materials. We show that coating noise arises not only from layer thickness fluctuations, but also from fluctuations of the interface between the coating and substrate, driven by fluctuating shear stresses of the coating. Although thickness fluctuations of different layers are statistically independent, there exists a finite coherence between the layers and the substrate-coating interface. In addition, photoelastic coefficients of the thin layers (so far not accurately measured) further influence the thermal noise, although at a relatively low level. Taking into account uncertainties in material parameters, we show that significant uncertainties still exist in estimating coating Brownian noise.

Hong, Ting; Yang, Huan; Gustafson, Eric K.; Adhikari, Rana X.; Chen, Yanbei

2013-04-01

427

Quasiperiodic metallic multilayers: Growth and superconductivity  

SciTech Connect

We have magnetron-sputtered a series of Mo-V superlattices which have a quasiperiodic layering in the growth direction. We have used the Fibonacci series as the generating rule for the nearly periodic structures and have verified their structure using high-angle x-ray diffractometry. The superconducting transition temperatures slowly increase as a function of the quasiperiodic wavelength ..lambda../sub F-italic/ while the initial upper-critical-field slopes parallel to the films decrease with increasing wavelength and the parallel upper-critical-field curves H-italic/sub c-italic//sub 2//sub chemically bond//sub chemically bond/ display a two-dimensional behavior that is not consistent with current ideas about critical-field behavior in multilayers.

Karkut, M.G.; Triscone, J.; Ariosa, D.; Fischer, O.

1986-09-15

428

Investigation of multilayer magnetic domain lattice file  

NASA Technical Reports Server (NTRS)

A theoretical and experimental investigation determined that current accessed self structured bubble memory devices have the potential of meeting projected data density and speed requirements. Device concepts analyzed include multilayer ferrimagnetic devices where the top layer contains a domain structure which defines the data location and the second contains the data. Current aperture and permalloy assisted current propagation devices were evaluated. Based on the result of this work more detailed device research was initiated. Detailed theoretical and experimental studies indicate that the difference in strip and threshold between a single bubble in the control layer and a double bubble which would exist in both the control layer and data layer is adequate to allow for detection of data. Detailed detector designs were investigated.

Torok, E. J.; Kamin, M.; Tolman, C. H.

1982-01-01

429

Multilayer insulation materials for reusable space vehicles.  

NASA Technical Reports Server (NTRS)

Results of an extensive study conducted to evaluate multilayer insulation (MLI) materials suitable for repeated space vehicle operation are presented. Materials studied were radiation shields, shield spacers, blanket face sheets, fasteners, and adhesives. The Superfloc MLI concept - Kapton shields goldized on both sides as the radiation barrier with Dacron flock tufts as the spacers - appeared to be an excellent MLI for reusable cryogenic tankage. Superfloc configurations consisting of various combinations of film, spacer, and adhesive materials were manufactured and tested. Tensile, flexing, expansion, and cycling tests were performed on goldized Kapton and Mylar Superfloc and Beta glass reinforced Pyre ML face sheet material. A face sheet material that retains its shape was developed. Polyphenylene oxide material was selected for fabricating lightweight twin and tri-pin fasteners, together with grommets, face sheets, and reinforcement slabs. Measured material thermal conductivity values are tabulated.

Leonhard, K. E.; Hyde, E. H.

1971-01-01

430

Purging of multilayer insulation by gas diffusion  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted to determine the time required to purge a multilayer insulation (MLI) panel with gaseous helium by means of gas diffusion to obtain a condensable (nitrogen) gas concentration of less than 1 percent within the panel. Two flat, rectangular MLI panel configurations, one incorporating a butt joint, were tested. The insulation panels consisted of 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The test results indicated that the rate which the condensable gas concentration at the edge or at the butt joint of an MLI panel was reduced was a significant factor in the total time required to reduce the condensable gas concentration within the panel to less than 1 percent. The experimental data agreed well with analytical predictions made by using a simple, one-dimensional gas diffusion model in which the boundary conditions at the edge of the MLI panel were time dependent.

Sumner, I. E.; Spuckler, C. M.

1976-01-01

431

Multilayered models for electromagnetic reflection amplitudes  

NASA Technical Reports Server (NTRS)

The remote sensing of snowpack characteristics with surface installations or with an airborne system could have important applications in water resource management and flood prediction. To derive some insight into such applications, the electromagnetic response of multilayer snow models is analyzed. Normally incident plane waves are assumed at frequencies ranging from 10 to the 6th power to 10 to the 10th power Hz, and amplitude reflection coefficients are calculated for models having various snow-layer combinations, including ice sheets. Layers are defined by a thickness, permittivity, and conductivity; the electrical parameters are constant or prescribed functions of frequency. To illustrate the effect of various layering combinations, results are given in the form of curves of amplitude reflection coefficients, versus frequency for a variety of models. Under simplifying assumptions, the snow thickness and effective dielectric constant can be estimated from the reflection coefficient variations as a function of frequency.

Linlor, W. I.

1976-01-01

432

Multilayer perceptron, fuzzy sets, and classification  

NASA Technical Reports Server (NTRS)

A fuzzy neural network model based on the multilayer perceptron, using the back-propagation algorithm, and capable of fuzzy classification of patterns is described. The input vector consists of membership values to linguistic properties while the output vector is defined in terms of fuzzy class membership values. This allows efficient modeling of fuzzy or uncertain patterns with appropriate weights being assigned to the backpropagated errors depending upon the membership values at the corresponding outputs. During training, the learning rate is gradually decreased in discrete steps until the network converges to a minimum error solution. The effectiveness of the algorithm is demonstrated on a speech recognition problem. The results are compared with those of the conventional MLP, the Bayes classifier, and the other related models.

Pal, Sankar K.; Mitra, Sushmita

1992-01-01

433

Multi-Layered Cancer Chromosomal Instability Phenotype  

PubMed Central

Whole-chromosomal instability (W-CIN) – unequal chromosome distribution during cell division – is a characteristic feature of a majority of cancer cells distinguishing them from their normal counterparts. The precise molecular mechanisms that may cause mis-segregation of chromosomes in tumor cells just recently became more evident. The consequences of W-CIN are numerous and play a critical role in carcinogenesis. W-CIN mediates evolution of cancer cell population under selective pressure and can facilitate the accumulation of genetic changes that promote malignancy. It has both tumor-promoting and tumor-suppressive effects, and their balance could be beneficial or detrimental for carcinogenesis. The characterization of W-CIN as a complex multi-layered adaptive phenotype highlights the intra- and extracellular adaptations to the consequences of genome reshuffling. It also provides a framework for targeting aggressive chromosomally unstable cancers. PMID:24377086

Roschke, Anna V.; Rozenblum, Ester

2013-01-01

434

Weyl semimetal in a topological insulator multilayer.  

PubMed

We propose a simple realization of the three-dimensional (3D) Weyl semimetal phase, utilizing a multilayer structure, composed of identical thin films of a magnetically doped 3D topological insulator, separated by ordinary-insulator spacer layers. We show that the phase diagram of this system contains a Weyl semimetal phase of the simplest possible kind, with only two Dirac nodes of opposite chirality, separated in momentum space, in its band structure. This Weyl semimetal has a finite anomalous Hall conductivity and chiral edge states and occurs as an intermediate phase between an ordinary insulator and a 3D quantum anomalous Hall insulator. We find that the Weyl semimetal has a nonzero dc conductivity at zero temperature, but Drude weight vanishing as T(2), and is thus an unusual metallic phase, characterized by a finite anomalous Hall conductivity and topologically protected edge states. PMID:22026796

Burkov, A A; Balents, Leon

2011-09-16

435

Chitin nanocrystal-xyloglucan multilayer thin films.  

PubMed

For the first time, the adsorption of xyloglucan (XG) on chitin nanocrystals (ChiNC) surface was proved using quartz crystal microbalance with dissipation (QCM-D) and by successfully building up spin-coated assisted layer-by-layer (LbL) structures on solid substrates. Several parameters in the adsorption process, such as ChiNC concentrations (0.5-3.0 g L(-1)), number of layers, or the outmost layer material (ChiNC or XG), were investigated to better understand the fabrication process of multilayer films. The thickness of the homogeneous film increased linearly with the number of bilayers, with an average thickness per bilayer of 12.3 nm. Additionally surface morphology was studied by atomic force microscopy (AFM), which revealed an almost completely covered surface after the adsorption of ChiNC. The final structures were found to have semireflective properties capable of being tuned by adjusting the ChiNC dispersion parameters. PMID:24328307

Villares, Ana; Moreau, Céline; Capron, Isabelle; Cathala, Bernard

2014-01-13

436

Properties of multilayer nonuniform holographic structures  

SciTech Connect

Experimental results and analysis of properties of multilayer nonuniform holographic structures formed in photopolymer materials are presented. The theoretical hypotheses is proved that the characteristics of angular selectivity for the considered structures have a set of local maxima, whose number and width are determined by the thicknesses of intermediate layers and deep holograms and that the envelope of the maxima coincides with the selectivity contour of a single holographic array. It is also experimentally shown that hologram nonuniformities substantially distort shapes of selectivity characteristics: they become asymmetric, the local maxima differ in size and the depths of local minima reduce. The modelling results are made similar to experimental data by appropriately choosing the nonuniformity parameters. (imaging and image processing. holography)

Pen, E F; Rodionov, Mikhail Yu [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2010-12-09

437

Method of fabricating a multilayer insulation blanket  

DOEpatents

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Gonczy, John D. (Oak Lawn, IL); Niemann, Ralph C. (Downers Grove, IL); Boroski, William N. (Aurora, IL)

1993-01-01

438

Multilayer insulation blanket, fabricating apparatus and method  

DOEpatents

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Gonczy, John D. (Oak Lawn, IL); Niemann, Ralph C. (Downers Grove, IL); Boroski, William N. (Aurora, IL)

1992-01-01

439

Methodology for determining multilayered temperature inversions  

NASA Astrophysics Data System (ADS)

The atmospheric boundary layer (ABL) exhibit multilayered thermal structure especially in polar atmosphere during extreme winters. These thermal inversions are originated based on the combined forcing of local and large scale synoptic meteorology. At the local scale the thermal inversion layer forms near the surface and plays a central role in controlling the surface radiative cooling; however, depending upon the large scale synoptic meteorological forcing, an upper level thermal inversion can also exist topping the local ABL. In this article a numerical methodology is developed to determine all-thermal inversion layers present in a given temperature profile and deduce some of their thermodynamic properties. The algorithm extract from the temperature profile the most important temperature variations defining thermal layers. This is accomplished by a inear interpolation function of variable length that minimizes an error function. The algorithm functionality is demonstrated on actual radiosonde profiles to deduce all-present inversion layers with an error fraction set independently.

Fochesatto, G. J.

2014-10-01

440

Skyrme crystal in bilayer and multilayer graphene  

NASA Astrophysics Data System (ADS)

The ground state of the two-dimensional electron systems in Bernal bilayer and ABC-stacked multilayer graphenes in the presence of a strong magnetic field is investigated with the Hartree-Fock approximation. Phase diagrams of the systems are obtained, focusing on charge density wave states including states with vortices of valley pseudospins (called a Skyrme crystal). The single-electron states in these stacked graphenes are given by two-component wave functions. That of the first excited Landau level has the same component as the lowest Landau level of the ordinary two-dimensional electrons. Because of this localized wave function, the Skyrme crystal has low energy in this first excited level up to four layers of graphene, when the interlayer distance is assumed to be infinitesimal. At the same time, bubble crystals are suppressed, so the phase diagram is different from that of a single-layer graphene.

Sakurai, Yasuhisa; Yoshioka, Daijiro

2012-01-01

441

Multilayer optical disc system using homodyne detection  

NASA Astrophysics Data System (ADS)

A write/read system using high-productivity multilayer optical discs was developed. The recording medium used in the system consists of planar recording layers and a separated guide layer, and is fabricated by web coating and lamination process. The recording layers in the medium are made of one-photon-absorption material, on which data can be recorded with a normal laser diode. The developed system is capable of focusing and tracking on the medium and amplifying readout signals by using phase-diversity homodyne detection. A highly layer-selective focusing method using homodyne detection was also proposed. This method obtains stable focus-error signals with clearly separated S-shaped curves even when layer spacing is quite narrow, causing large interlayer crosstalk. Writing on the medium and reading with the signal amplification effect of homodyne detection was demonstrated. In addition, the effectiveness of the method was experimentally evaluated.

Kurokawa, Takahiro; Ide, Tatsuro; Tanaka, Yukinobu; Watanabe, Koichi

2014-09-01

442

Wrapped multilayer insulation design and testing  

NASA Astrophysics Data System (ADS)

New vehicles need improved cryogenic propellant storage and transfer capabilities for long duration missions. Multilayer insulation (MLI) for cryogenic propellant feedlines is much less effective than MLI tank insulation, with heat leak into spiral wrapped MLI on pipes 3-10 times higher than conventional tank MLI. Better insulation for cryogenic feed lines is an important enabling technology that could help NASA reach cryogenic propellant storage and transfer requirements. Improved insulation for Ground Support Equipment could reduce cryogen losses during launch vehicle loading. Wrapped-MLI (WMLI) is a high performance multilayer insulation using innovative discrete spacer technology specifically designed for cryogenic transfer lines and Vacuum Jacketed Pipe (VJP) to reduce heat flux. The poor performance of traditional MLI wrapped on feed lines is due in part to compression of the MLI layers, with increased interlayer contact and heat conduction. WMLI uses discrete spacers that maintain precise layer spacing, with a unique design to reduce heat leak. A Triple Orthogonal Disk spacer was engineered to minimize contact area/length ratio and reduce solid heat conduction for use in concentric MLI configurations. A new insulation, WMLI, was developed and tested. Novel polymer spacers were designed, analyzed and fabricated; different installation techniques were examined; and rapid prototype nested shell components to speed installation on real world piping were designed and tested. Prototypes were installed on tubing set test fixtures and heat flux measured via calorimetry. WMLI offered superior performance to traditional MLI installed on cryogenic pipe, with 2.2 W/m2 heat flux compared to 26.6 W/m2 for traditional spiral wrapped MLI (5 layers, 77-295 K). WMLI as inner insulation in VJP can offer heat leaks as low as 0.09 W/m, compared to industry standard products with 0.31 W/m. WMLI could enable improved spacecraft cryogenic feedlines and industrial hot/cold transfer lines.

Dye, S. A.; Tyler, P. N.; Mills, G. L.; Kopelove, A. B.

2014-11-01

443

Nanoscale thin film ceramic fuel cells  

NASA Astrophysics Data System (ADS)

The ceramic fuel cell (CFC) refers to fuel cells employing solid state ceramic electrolytes, including two types of fuel cells: the solid oxide fuel cell (SOFC) and the proton-conducting oxide fuel cell (PCOFC). The goal of this study is to minimize Ohmic losses and activation losses at the electrolyte and electrode-electrolyte interface respectively by engineering CFC components to run fuel cells at reduced temperatures. Successful synthesis of nano-scale oxide ion-conducting yttria-stabilized zirconia (YSZ) with an optimal Y:Zr composition of 8 molar % yttria was demonstrated using atomic layer deposition (ALD). Structural analyses of ALD YSZ films grown on amorphous Si3N4 showed a polycrystalline morphology with volume expansion confirmed by x-ray diffraction (XRD), x-ray reflection (XRR) and transmission electron microscopy (TEM) techniques. Fine spherical grains were observed in atomic force microscopy (AFM) images. Fuel cell performance data between 265˜450°C showed maximum power densities of 28˜587mW/cm 2, respectively. Performance enhancement originated from an increase in exchange current density at the electrode-electrolyte interface. Our hypothesis is that the polycrystalline surface of the membrane with grains in several tens of nanometers is responsible for the high exchange current density through the introduction of many grains and grain boundaries. This speculation is based on the surface morphology of the ALD YSZ or RF sputtered YSZ consisting of 20˜30nm grains measured by AFM. In contrast, the size of grains in bulk YSZ is on the order of several microns. To investigate relationship between surface morphology and fuel cell performance, we traced the surface incorporation and diffusion of oxygen ions using 18O isotopes and the secondary ion mass spectrometry (SIMS) technique. ALD films were grown on top of Si3N4-buffered Si(100) wafers and single crystal YSZ(100) substrates. 100mum thick polycrystalline YSZ samples were used to investigate the role of grain and grain boundaries in cathodic reactions. Diffusivity and surface exchange rate were calculated by fitting SIMS depth profiles. Diffusivities of all of tested samples including single crystal YSZ(100) were aligned well on a single line in the Arrhenius plot indicating that there is no enhancement in bulk diffusion by the ALD YSZ surface coating. However, the surface exchange rate on the ALD YSZ coated YSZ(100) increased by a factor of 2.4˜3.0 in comparison with the one from bare YSZ(100). AFM morphology analysis suggested that the ALD YSZ coating formed granular surface and we speculated that this granular surface enhanced the exchange rate by introducing additional gas-ion contact sites. We studied yttrium-doped barium zirconate (BYZ), a proton conducting perovskite, which attracts attention as a new electrolyte material for future ceramic fuel cells due to its high ionic conductivity and chemical stability. The ionic conductivity of nano-scale BYZ films (60-670nm) epitaxially grown on single crystalline MgO(100) by pulsed laser deposition (PLD) was investigated in relation to the crystal and grain structures. Crystal structure and surface morphology changes were identified by XRD and AFM analyses, respectively. Ionic conductivity was measured as a function of temperature and film thickness. Measured conductivities and the resulting activation energies were in good agreement with the reference value for bulk BYZ. Enhanced conductivity was observed in thin samples oriented in (100) texture, while the ionic conductivity of thick polycrystalline films showed no thickness dependence. The difference is likely due to morphological changes as the film grows thicker. This was confirmed by AFM and XRD analyses of thicker films, which feature granular structure in the vicinity of the surface. Fuel cells with 130nm thick PLD BYZ electrolytes were successfully fabricated. The best performing PLD BYZ cells exhibited a maximum power density of 11˜120mW/cm2 at 300˜450°C. Fuel cells with PLD BYZ electrolytes performed inferior to conventional polymer fuel

Shim, Joon Hyung

444

Mechanical properties of multilayer boron nitride with different stacking orders  

NASA Astrophysics Data System (ADS)

The mechanical properties of multilayer boron nitride (BN) with various stacking orders are characterized by ab initio calculations. Based on the density functional theory (DFT), the values of elastic constants of AB bilayer, ABA and ABC trilayer and graphite-like BN in the harmonic elastic deformation range are revealed. DFT calculations are performed in the context of generalized gradient approximation (GGA) and by adopting the Perdew-Burke-Ernzerhof (PBE) exchange correlation. This investigation shows that Young's modulus and Poisson's ratio of multilayer BN are lower than those of monolayer BN. A comparative study on the mechanical properties of multilayer BN with different stacking orders is presented. It is indicated that the mechanical properties of multilayer BN are dependent on the number of layers and their stacking order.

Mirnezhad, M.; Ansari, R.; Rouhi, H.

2013-01-01

445

Interdiffusion in W/Si Multilayers with Boron Carbide Interlayers  

SciTech Connect

W/Si multilayers with B{sub 4}C as a diffusion barrier were deposited using ion beam sputtering technique. It was found that incorporation of B{sub 4}C at both interfaces of Si enhances the reflectivity of the multilayer. Though the interface of W/Si or W/B{sub 4}C has been studied in literature, what happens at Si/B{sub 4}C interfaces is largely unknown. This is primarily due to absence of contrast between Si/B{sub 4}C for x-rays. For neutrons there is significant contrast between Si and B{sub 4}C, therefore we used neutron reflectivity to study thermal stability of Si/B{sub 4}C multilayers. It was found that up to an annealing temperature of 573 K, the multilayer remains intact however at higher temperature interdiffusion starts.

Potdar, Satish; Gupta, M.; Gupta, A. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452 001 (India); Schneider, M.; Stahn, J. [Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

2011-07-15

446

The Use of Genetic Algorithms in Multilayer Mirror Optimization  

E-print Network

Department of Physics and Astronomy Brigham Young University, Provo, UT 84602 #12;June 10, 1999, GA.doc, page 2 Abstract We have applied the genetic algorithm to extreme ultraviolet (XUV) multilayer mirror

Hart, Gus

447

Polyelectrolyte multilayers for tunable release of antibiotics and other therapeutics  

E-print Network

Polyelectrolyte multilayers (PEMs) were fabricated via the layer-by-layer (LbL) deposition process, incorporating hydrolytically degradable poly([beta]-amino esters) to result in biodegradable PEMs that can release active ...

Chuang, Helen F

2008-01-01

448

Computer-aided design for multilayer microfluidic chips  

E-print Network

Microfluidic chips fabricated by multilayer soft lithography are emerging as "lab-on-a-chip" systems that can automate biological experiments. As we are able to build more complex microfluidic chips with thousands of ...

Amin, Nada

2009-01-01

449

Tunable drug loading and release from polypeptide multilayer nanofilms  

PubMed Central

Polypeptide multilayer nanofilms were prepared using electrostatic layer-by-layer self-assembly nanotechnology. Small charged drug molecules (eg, cefazolin, gentamicin, and methylene blue) were loaded in polypeptide multilayer nanofilms. Their loading and release were found to be pH-dependent and could also be controlled by changing the number of film layers and drug incubation time, and applying heat-treatment after film formation. Antibioticloaded polypeptide multilayer nanofilms showed controllable antibacterial properties against Staphylococcus aureus. The developed biodegradable polypeptide multilayer nanofilms are capable of loading both positively- and negatively-charged drug molecules and promise to serve as drug delivery systems on biomedical devices for preventing biomedical device-associated infection, which is a significant clinical complication for both civilian and military patients. PMID:19421369

Jiang, Bingbing; Li, Bingyun

2009-01-01

450

X-ray polarimeter with a transmission multilayer  

SciTech Connect

We fabricated a novel x-ray polarimeter with a transmission multilayer and measured its performance with synchrotron radiation. A self standing multilayer with seven Mo/Si bilayers was installed with an incident angle of 45 deg. in front of a back-illuminated CCD. The multilayer can be rotated around the normal direction of the CCD keeping an incident angle of 45 deg. This polarimeter can be easily installed along the optical axis of x-ray optics. By using the CCD as a photon counting detector with a moderate energy resolution, the polarization of photons in a designed energy band can be measured along with the image. At high photon energies, where the multilayer is transparent, the polarimeter can be used for imaging and spectroscopic observations. We confirmed a modulation factor of 45% with 45% and 17% transmission for P- and S-polarization, respectively.

Kitamoto, Shunji; Murakami, Hiroshi; Shishido, Youich; Gotoh, Norimitsu; Shibata, Takuma; Saito, Kousuke; Watanabe, Takeshi; Kanai, Jun'ichi; Takenaka, Eri; Nagasaki, Kenta; Yoshida, Masaki; Takei, Dai [Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan); Morii, Mikio [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)

2010-02-15

451

Ballistic resistance of multi-layered steel shields  

E-print Network

In this thesis, the ballistic resistance of multi-layered steel shields against projectile impact at the sub-ordnance velocity is evaluated using finite element simulations. Eight types of projectiles of different weight ...

Huang, Min, S.M. Massachusetts Institute of Technology

2007-01-01

452

A reservoir management strategy for multilayered reservoirs in eastern Venezuela  

E-print Network

A reservoir management strategy has been developed for a field located in eastern Venezuela. The field contains deep, high pressure, multilayer reservoirs. A thorough formation evaluation was accomplished using the log data, core data, PVT data...

Espinel Diaz, Arnaldo Leopoldo

2012-06-07

453

Infrared suppression by hybrid EUV multilayer---IR etalon structures  

NASA Astrophysics Data System (ADS)

We have developed a multilayer mirror for extreme UV (EUV) radiation (13.5nm), which has near-zero reflectance for IR line radiation (10.6?m). The EUV reflecting multilayer is based on alternating B4C and Si layers. Substantial transparency of these materials with respect to the IR radiation allowed the integration of the multilayer coating in a resonant quarter-wave structure for 10.6?m. Samples were manufactured using magnetron sputtering deposition technique and demonstrated suppression of the IR radiation by up to 3 orders of magnitude. The EUV peak reflectance amounts 45% at 13.5nm, with a bandwidth at FWHM being 0.284nm. Therefore such a mirror could replace conventional multilayer mirrors to suppress undesired spectral components in monochromatic imaging applications, including EUV photolithography.

Medvedev, V. V.; Yakshin, A. E.; van de Kruijs, R. W. E.; Krivtsun, V. M.; Yakunin, A. M.; Koshelev, K. N.; Bijkerk, F.

2011-09-01

454

Developing Multilayer Thin Film Strain Sensors With High Thermal Stability  

NASA Technical Reports Server (NTRS)

A multilayer thin film strain sensor for large temperature range use is under development using a reactively-sputtered process. The sensor is capable of being fabricated in fine line widths utilizing the sacrificial-layer lift-off process that is used for micro-fabricated noble-metal sensors. Tantalum nitride films were optimized using reactive sputtering with an unbalanced magnetron source. A first approximation model of multilayer resistance and temperature coefficient of resistance was used to set the film thicknesses in the multilayer film sensor. Two multifunctional sensors were fabricated using multilayered films of tantalum nitride and palladium chromium, and tested for low temperature resistivity, TCR and strain response. The low temperature coefficient of resistance of the films will result in improved stability in thin film sensors for low to high temperature use.

Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M., III

2006-01-01

455

Prediction of Forming Limits of the Multilayer Metallic Sheet  

NASA Astrophysics Data System (ADS)

In this paper, the forming limit of a multilayer metallic steel sheet is numerically investigated. Multilayer metallic sheets are an emerging sheet metal that is designed to achieve both high strength and enough formability, which is seriously demanded especially from the automotive industry. Unfortunately, its mechanism of enhanced ductility, fracture behavior, and forming limits have not been sufficiently studied. Therefore, a new stress-strain curve formula is constructed so as to precisely predict the forming limit that is influenced by the unique characteristics of the multilayer metallic sheets. Tensile and stretching experiment on a 15-layer multilayer metallic sheet is conducted, then the results are used to verify the effectiveness of the presented stress-strain expression, and the predicted forming limits are compared to the experimental value, resulted in a good agreement.

Oya, T.; Jeong, C.; Yanagimoto, J.

2011-08-01

456

Multilayer mirrors and filters for imaging the earth's inner magnetosphere  

NASA Technical Reports Server (NTRS)

The requirements for imaging the inner magnetosphere in the light of 304-A He(+) emission are examined. The expected EUV emission spectrum of the inner magnetosphere is used to establish guidelines for the performance of the imager's multilayer mirrors and filters. The design of multilayer mirrors and the results of a computer search that determines the best multilayer mirror design for this application are discussed. B4C, Be, Si, and SiC are identified as promising top-layer materials for a multilayer 304-A mirror, while Al, Mg, and Mg2Si are recommended for other layers. Si-passivated Te and a combination of Al or Si with B or C are promising filter materials for this application.

Schulze, Dean W.; Sandel, Bill R.; Broadfoot, A. L.

1993-01-01

457

Multilayer shells: Geometrically-exact formulation of equations of motion  

E-print Network

of Plantema (1966). More recently, there are some review papers on formulations for multilayer plates (Noor and Burton, 1989) and more particularly for sandwich plates and shells (Noor et al., 1996). The readers

Vu-Quoc, Loc

458

Magnetic switching and magnetoresistance in nanoscale spin tunnel junctions  

E-print Network

Magnetic switching and magnetoresistance in nanoscale spin tunnel junctions M. Urech,a) V magnetic tunnel junctions in both multijunction arrays and double-tunnel junction geometries have been studied. The junctions exhibit magnetoresistance MR and change their resistance by 10% depending

Haviland, David

459

Nanoscale On-Chip Decoupling Capacitors Mikhail Popovich  

E-print Network

Nanoscale On-Chip Decoupling Capacitors Mikhail Popovich Qualcomm, Inc. 5775 Morehouse Drive San-- A distributed on-chip decoupling capacitor network is proposed in this paper to replace one large capacitor. A system of distributed on-chip decoupling capacitors is shown to provide an efficient solution

Friedman, Eby G.

460

Comment on `Nanoscale water capillary bridges under deeply negative  

E-print Network

saturated vapor pressure Psat. Because of the cohesion forces between particles, the pressure can evenComment on `Nanoscale water capillary bridges under deeply negative pressure' [Chem. Phys. Lett micro- scope tip and a silicon wafer. They deduced the pressure of liquid water inside the capillary

Balibar, Sébastien